# main.py
import sys
import os
import random
import hashlib
import subprocess
import json
import asyncio
import shutil
from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QWidget, QTabWidget, QVBoxLayout, 
    QHBoxLayout, QLabel, QPushButton, QLineEdit, QComboBox, 
    QTableWidget, QTableWidgetItem, QSlider, QFormLayout, QTextEdit, QFrame, QMessageBox, QFileDialog
)
from PyQt6.QtCore import Qt, QUrl
from PyQt6.QtMultimedia import QMediaPlayer, QAudioOutput
from PyQt6.QtGui import QFont

# Third-Party Tooling
import genanki
import edge_tts
from PIL import Image, ImageDraw, ImageFont

# Internal Project Module Imports
from database.connection import init_db, get_connection
from core.bulk_importer import BulkImporter
from core.clean_glossary import GlossaryCleaner

class SpanishTrainerApp(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Castilian Voice Trainer Pro")
        self.setMinimumSize(1200, 800)
        
        # 1. Initialize schema structures and check ingestion status
        self.ensure_database_populated()
        
        # Load system persistent settings from DB (including sleep-learning fields)
        self.load_system_settings()
        
        # Audio Player Architecture Setup
        self.media_player = QMediaPlayer()
        self.audio_output = QAudioOutput()
        self.media_player.setAudioOutput(self.audio_output)
        
        self.current_flashcard_id = None
        self.current_sandbox_es_id = None
        self.current_sandbox_en_id = None
        self.flashcard_ids_pool = []  # Tracks currently filtered study list IDs
        
        # Central Main Window Tabs Interface
        self.tabs = QTabWidget()
        self.setCentralWidget(self.tabs)
        
        self.init_phrase_sandbox_tab()
        self.init_flashcard_reviewer_tab()
        self.init_settings_tab()
        
        # 2. Populate table grids on initialization
        self.refresh_crud_table()
        self.refresh_review_table()

    def ensure_database_populated(self):
        """Forces database configuration structure and triggers pipeline execution if empty."""
        print("🗄️ Verification Pass: Running schema configuration scripts...")
        init_db()
        
        conn = get_connection()
        cursor = conn.cursor()
        
        # Ensure our settings table and key columns are structurally sound
        cursor.execute("CREATE TABLE IF NOT EXISTS settings (key TEXT PRIMARY KEY, value TEXT);")
        
        # Seamlessly inject duration column into phrases if it doesn't exist
        cursor.execute("PRAGMA table_info(phrases);")
        columns = [row[1] for row in cursor.fetchall()]
        if "duration" not in columns:
            print("🔄 Modifying phrases schema to support floating-point duration tracking...")
            cursor.execute("ALTER TABLE phrases ADD COLUMN duration REAL;")
            conn.commit()
        
        try:
            cursor.execute("SELECT COUNT(*) FROM translations")
            count = cursor.fetchone()[0]
            print(f"📊 Current Translation Pairs found in database: {count}")
        except Exception as e:
            print(f"⚠️ Table check encountered an issue (likely empty tables): {e}")
            count = 0
        finally:
            conn.close()
        
        if count == 0:
            print("🗄️ Database tables are empty. Triggering glossary reader pipeline...")
            pdf_file = "aula_int_plus_1_glos_en_alfa.pdf"
            
            if os.path.exists(pdf_file):
                importer = BulkImporter()
                importer.import_pdf_glossary(pdf_file, "Aula Internacional Plus 1")
                
                cleaner = GlossaryCleaner()
                cleaner.process_database_clean()
                print("✨ Ingestion pipeline processing sequence successfully completed.")
            else:
                print(f"❌ Error: Source document '{pdf_file}' is missing from the directory root.")

    def load_system_settings(self):
        """Loads persistent variables from the key-value settings table."""
        # Baseline internal fallback defaults
        self.anki_export_dir = os.getcwd()
        self.video_export_dir = os.getcwd()
        self.video_first_lang = "English First (en -> es)"
        self.video_repeats_count = "3"
        self.video_pause_duration = "4.0"
        
        conn = get_connection()
        cursor = conn.cursor()
        try:
            cursor.execute("SELECT key, value FROM settings")
            rows = cursor.fetchall()
            for row in rows:
                if row[0] == "anki_export_directory":
                    self.anki_export_dir = row[1]
                elif row[0] == "video_export_directory":
                    self.video_export_dir = row[1]
                elif row[0] == "video_first_language":
                    self.video_first_lang = row[1]
                elif row[0] == "video_repeats_count":
                    self.video_repeats_count = row[1]
                elif row[0] == "video_pause_duration":
                    self.video_pause_duration = row[1]
        except Exception as e:
            print(f"⚠️ Failed to read application settings from database: {e}")
        finally:
            conn.close()

    def save_setting_to_db(self, key, value):
        """Updates or inserts a specific system runtime variable into the database."""
        conn = get_connection()
        cursor = conn.cursor()
        try:
            cursor.execute("INSERT OR REPLACE INTO settings (key, value) VALUES (?, ?)", (key, value))
            conn.commit()
            
            # Sync the application runtime settings instantly back to memory variables
            if key == "video_first_language":
                self.video_first_lang = value
            elif key == "video_repeats_count":
                self.video_repeats_count = value
            elif key == "video_pause_duration":
                self.video_pause_duration = value
        except Exception as e:
            print(f"❌ Critical: Failed to save setting '{key}': {e}")
        finally:
            conn.close()

    def get_or_generate_audio_duration(self, phrase_id, text_str, lang):
        """
        Ensures a target audio track exists on disk, reads its run length 
        via ffprobe, caches the duration field inside SQLite, and returns the float timing block.
        """
        if not phrase_id:
            return 2.5

        safe_name = "".join([c for c in text_str if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
        os.makedirs("media", exist_ok=True)
        target_file = f"media/{safe_name}_{lang}_female.mp3"

        # 1. Generate audio track dynamically if missing
        if not os.path.exists(target_file):
            try:
                voice = "es-ES-ElviraNeural" if lang == "es" else "en-GB-SoniaNeural"
                communicate = edge_tts.Communicate(text_str, voice)
                asyncio.run(communicate.save(target_file))
            except Exception as tts_err:
                print(f"❌ Core TTS System Exception: {tts_err}")
                return 2.5

        # 2. Return cached value from DB if it exists and isn't null
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("SELECT duration FROM phrases WHERE id = ?", (phrase_id,))
        cached_row = cursor.fetchone()
        
        if cached_row and cached_row[0] is not None:
            conn.close()
            return float(cached_row[0])

        # 3. Calculate audio duration via ffprobe and store it permanently
        try:
            cmd = [
                'ffprobe', '-v', 'quiet', '-print_format', 'json',
                '-show_entries', 'format=duration', target_file
            ]
            result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
            data = json.loads(result.stdout)
            duration = float(data['format']['duration'])
            
            cursor.execute("UPDATE phrases SET duration = ? WHERE id = ?", (duration, phrase_id))
            conn.commit()
            print(f"💾 Track length calculated and stored globally: {duration}s -> Phrase ID {phrase_id}")
        except Exception as e:
            print(f"⚠️ Track structure analysis warning for {target_file}: {e}")
            duration = 2.5
        finally:
            conn.close()

        return duration

    # =====================================================================
    # 🗄️ TAB 1: TRANSLATION-CENTRIC PHRASE SANDBOX (CRUD)
    # =====================================================================
    def init_phrase_sandbox_tab(self):
        tab = QWidget()
        layout = QHBoxLayout(tab)
        
        left_panel = QVBoxLayout()
        
        filter_layout = QHBoxLayout()
        filter_layout.addWidget(QLabel("🔍 Text Filter:"))
        self.search_text_input = QLineEdit()
        self.search_text_input.setPlaceholderText("Search Spanish or English text blocks...")
        self.search_text_input.textChanged.connect(self.refresh_crud_table)
        filter_layout.addWidget(self.search_text_input)
        
        filter_layout.addWidget(QLabel("📂 Context:"))
        self.search_context_input = QLineEdit()
        self.search_context_input.setPlaceholderText("e.g. U2")
        self.search_context_input.setMaximumWidth(130)
        self.search_context_input.textChanged.connect(self.refresh_crud_table)
        filter_layout.addWidget(self.search_context_input)
        
        left_panel.addLayout(filter_layout)
        
        self.translation_table = QTableWidget()
        self.translation_table.setColumnCount(6)
        self.translation_table.setHorizontalHeaderLabels([
            "TX ID", "Spanish Phrase", "English Translation", "Type", "Source Context", "Deck Assignment"
        ])
        self.translation_table.itemSelectionChanged.connect(self.handle_table_row_select)
        left_panel.addWidget(self.translation_table)
        
        nav_layout = QHBoxLayout()
        self.btn_row_up = QPushButton("🔼 Previous Pair")
        self.btn_row_down = QPushButton("🔽 Next Pair")
        self.btn_row_up.clicked.connect(lambda: self.step_table_row(-1))
        self.btn_row_down.clicked.connect(lambda: self.step_table_row(1))
        nav_layout.addWidget(self.btn_row_up)
        nav_layout.addWidget(self.btn_row_down)
        left_panel.addLayout(nav_layout)
        
        right_panel = QVBoxLayout()
        form_frame = QFrame()
        form_frame.setFrameShape(QFrame.Shape.StyledPanel)
        form_layout = QFormLayout(form_frame)
        
        self.input_tx_id = QLineEdit()
        self.input_tx_id.setReadOnly(True)
        self.input_tx_id.setPlaceholderText("Auto-Increment ID")
        
        self.input_text_es = QTextEdit()
        self.input_text_es.setMaximumHeight(75)
        
        self.input_text_en = QTextEdit()
        self.input_text_en.setMaximumHeight(75)
        
        self.combo_type = QComboBox()
        self.combo_type.addItems(["phrase", "sentence", "noun", "verb", "adjective"])
        
        self.input_context = QLineEdit()
        self.input_context.setPlaceholderText("e.g., U8_5A")
        
        self.input_tags = QLineEdit()
        self.input_tags.setPlaceholderText("e.g., irregular_er boots_verb")
        
        self.input_deck_tag = QLineEdit()
        self.input_deck_tag.setPlaceholderText("Anki Sub-deck Hierarchy")
        
        button_qss = """
            QPushButton {
                background-color: #f0f0f0;
                border: 1px solid #c0c0c0;
                border-radius: 4px;
                font-size: 11px;
                font-weight: bold;
                color: #333333;
            }
            QPushButton:hover {
                background-color: #e0e0e0;
                border: 1px solid #a0a0a0;
            }
            QPushButton:pressed {
                background-color: #d0d0d0;
            }
        """
        
        es_header_layout = QHBoxLayout()
        es_header_layout.setContentsMargins(0, 5, 0, 5)
        es_header_layout.addWidget(QLabel("<b>🇪🇸 Castilian Spanish Text Element:</b>"))
        
        self.btn_play_sandbox_es = QPushButton("Play 🔊")
        self.btn_play_sandbox_es.setFixedWidth(75)
        self.btn_play_sandbox_es.setFixedHeight(24)
        self.btn_play_sandbox_es.setStyleSheet(button_qss)
        self.btn_play_sandbox_es.clicked.connect(self.handle_sandbox_play_es)
        es_header_layout.addWidget(self.btn_play_sandbox_es)
        
        self.combo_speed_es = QComboBox()
        self.combo_speed_es.addItems(["0.50x", "0.75x", "1.00x", "1.25x", "1.50x"])
        self.combo_speed_es.setCurrentText("1.00x")
        self.combo_speed_es.setFixedWidth(70)
        self.combo_speed_es.setFixedHeight(24)
        es_header_layout.addWidget(self.combo_speed_es)
        es_header_layout.addStretch()

        en_header_layout = QHBoxLayout()
        en_header_layout.setContentsMargins(0, 5, 0, 5)
        en_header_layout.addWidget(QLabel("<b>🇬🇧 English Target Translation:</b>"))
        
        self.btn_play_sandbox_en = QPushButton("Play 🔊")
        self.btn_play_sandbox_en.setFixedWidth(75)
        self.btn_play_sandbox_en.setFixedHeight(24)
        self.btn_play_sandbox_en.setStyleSheet(button_qss)
        self.btn_play_sandbox_en.clicked.connect(self.handle_sandbox_play_en)
        en_header_layout.addWidget(self.btn_play_sandbox_en)
        
        self.combo_speed_en = QComboBox()
        self.combo_speed_en.addItems(["0.50x", "0.75x", "1.00x", "1.25x", "1.50x"])
        self.combo_speed_en.setCurrentText("1.00x")
        self.combo_speed_en.setFixedWidth(70)
        self.combo_speed_en.setFixedHeight(24)
        en_header_layout.addWidget(self.combo_speed_en)
        en_header_layout.addStretch()

        grammar_header_layout = QHBoxLayout()
        grammar_header_layout.setContentsMargins(0, 5, 0, 5)
        grammar_header_layout.addWidget(QLabel("<b>📝 Grammar / Usage Note:</b>"))
        grammar_header_layout.addStretch()
        
        self.input_grammar_note = QTextEdit()
        self.input_grammar_note.setMaximumHeight(75)
        self.input_grammar_note.setPlaceholderText("e.g., feminine variant...")
        
        form_layout.addRow("<b>Translation Link ID:</b>", self.input_tx_id)
        form_layout.addRow(es_header_layout)
        form_layout.addRow(self.input_text_es)
        form_layout.addRow(en_header_layout)
        form_layout.addRow(self.input_text_en)
        form_layout.addRow(grammar_header_layout)
        form_layout.addRow(self.input_grammar_note)
        form_layout.addRow("Classification Profile:", self.combo_type)
        form_layout.addRow("Source Context ID (Raw):", self.input_context)
        form_layout.addRow("Anki Note Tags:", self.input_tags)
        form_layout.addRow("<b>Target Deck Scope:</b>", self.input_deck_tag)
        
        crud_buttons = QHBoxLayout()
        self.btn_save = QPushButton("➕ Create Pair")
        self.btn_update = QPushButton("💾 Update Node")
        self.btn_delete = QPushButton("🗑️ Sever Link")
        
        self.btn_save.clicked.connect(self.crud_create_pair)
        self.btn_update.clicked.connect(self.crud_update_pair)
        self.btn_delete.clicked.connect(self.crud_delete_pair)
        
        crud_buttons.addWidget(self.btn_save)
        crud_buttons.addWidget(self.btn_update)
        crud_buttons.addWidget(self.btn_delete)
        
        right_panel.addWidget(QLabel("<h3>Translation Node Management Matrix</h3>"))
        right_panel.addWidget(form_frame)
        right_panel.addLayout(crud_buttons)
        right_panel.addStretch()
        
        layout.addLayout(left_panel, stretch=4)
        layout.addLayout(right_panel, stretch=3)
        
        self.tabs.addTab(tab, "🗄️ Phrase Sandbox (CRUD)")

    # =====================================================================
    # 🃏 TAB 2: FLASHCARD STUDY MODULE
    # =====================================================================
    def init_flashcard_reviewer_tab(self):
        tab = QWidget()
        layout = QHBoxLayout(tab)
        
        left_panel = QVBoxLayout()
        
        filter_layout = QHBoxLayout()
        filter_layout.addWidget(QLabel("📂 Context:"))
        self.review_context_filter = QLineEdit()
        self.review_context_filter.setPlaceholderText("Filter Context...")
        self.review_context_filter.textChanged.connect(self.refresh_review_table)
        filter_layout.addWidget(self.review_context_filter)
        
        filter_layout.addWidget(QLabel("🏷️ Tag:"))
        self.review_tag_filter = QLineEdit()
        self.review_tag_filter.setPlaceholderText("Filter Tag...")
        self.review_tag_filter.textChanged.connect(self.refresh_review_table)
        filter_layout.addWidget(self.review_tag_filter)
        
        left_panel.addLayout(filter_layout)
        
        self.review_table = QTableWidget()
        self.review_table.setColumnCount(4)
        self.review_table.setHorizontalHeaderLabels(["Tx ID", "Spanish Phrase", "Context", "Tags"])
        self.review_table.itemSelectionChanged.connect(self.handle_review_table_select)
        left_panel.addWidget(self.review_table)
        
        layout.addLayout(left_panel, stretch=4)
        
        right_panel = QVBoxLayout()
        
        card_frame = QFrame()
        card_frame.setStyleSheet("background-color: #ffffff; border: 2px solid #bdc3c7; border-radius: 12px;")
        card_layout = QVBoxLayout(card_frame)
        card_frame.setMinimumHeight(280)
        
        self.lbl_card_text = QLabel("Select a row or click 'Next Card' to initiate...")
        self.lbl_card_text.setAlignment(Qt.AlignmentFlag.AlignCenter)
        self.lbl_card_text.setFont(QFont("Arial", 20, QFont.Weight.Bold))
        self.lbl_card_text.setWordWrap(True)
        self.lbl_card_text.setStyleSheet("color: #2c3e50; border: none; padding: 20px;")
        
        self.lbl_card_meta = QLabel("")
        self.lbl_card_meta.setAlignment(Qt.AlignmentFlag.AlignCenter)
        self.lbl_card_meta.setFont(QFont("Arial", 11))
        self.lbl_card_meta.setStyleSheet("color: #7f8c8d; border: none;")
        
        card_layout.addStretch()
        card_layout.addWidget(self.lbl_card_text)
        card_layout.addWidget(self.lbl_card_meta)
        card_layout.addStretch()
        right_panel.addWidget(card_frame, stretch=4)
        
        playback_layout = QHBoxLayout()
        playback_layout.addWidget(QLabel("🔊 Voice Speed:"))
        self.slider_review_speed = QSlider(Qt.Orientation.Horizontal)
        self.slider_review_speed.setMinimum(50)   
        self.slider_review_speed.setMaximum(150)  
        self.slider_review_speed.setValue(100)    
        self.lbl_review_speed = QLabel("1.00x")
        self.slider_review_speed.valueChanged.connect(self.handle_live_speed_change)
        playback_layout.addWidget(self.slider_review_speed)
        playback_layout.addWidget(self.lbl_review_speed)
        right_panel.addLayout(playback_layout)
        
        action_buttons = QHBoxLayout()
        self.btn_play_voice = QPushButton("🗣️ Play Voice Track")
        self.btn_flip_card = QPushButton("👁️ Reveal English Partner")
        
        self.btn_play_voice.clicked.connect(self.handle_play_voice)
        self.btn_flip_card.clicked.connect(self.handle_flip_card)
        
        action_buttons.addWidget(self.btn_play_voice)
        action_buttons.addWidget(self.btn_flip_card)
        right_panel.addLayout(action_buttons)
        
        right_panel.addSpacing(15)
        
        bottom_utility_layout = QHBoxLayout()
        self.btn_export_anki = QPushButton("📦 Export Anki Deck")
        self.btn_export_video = QPushButton("🎬 Export Video")
        self.btn_load_next = QPushButton("➡️ Next Card")
        
        self.btn_export_anki.clicked.connect(self.handle_export_anki_deck)
        self.btn_export_video.clicked.connect(self.handle_export_video_assets)
        self.btn_load_next.clicked.connect(self.handle_load_next_card)
        
        utility_qss = "QPushButton { font-weight: bold; background-color: #eaf2f8; padding: 6px; border-radius: 4px; }"
        self.btn_export_anki.setStyleSheet(utility_qss)
        self.btn_export_video.setStyleSheet(utility_qss)
        self.btn_load_next.setStyleSheet("QPushButton { font-weight: bold; background-color: #d5f5e3; padding: 6px; border-radius: 4px; }")
        
        bottom_utility_layout.addWidget(self.btn_export_anki)
        bottom_utility_layout.addWidget(self.btn_export_video)
        bottom_utility_layout.addStretch()
        bottom_utility_layout.addWidget(self.btn_load_next)
        right_panel.addLayout(bottom_utility_layout)
        
        layout.addLayout(right_panel, stretch=3)
        self.tabs.addTab(tab, "🃏 Flashcard Review")

    # =====================================================================
    # ⚙️ TAB 3: SYSTEM HARDWARE & EXPORT SETTINGS
    # =====================================================================
    def init_settings_tab(self):
        tab = QWidget()
        layout = QVBoxLayout(tab)
        
        settings_frame = QFrame()
        settings_frame.setFrameShape(QFrame.Shape.StyledPanel)
        form_layout = QFormLayout(settings_frame)
        
        anki_layout = QHBoxLayout()
        self.line_anki_dir = QLineEdit(self.anki_export_dir)
        self.line_anki_dir.setReadOnly(True)
        btn_browse_anki = QPushButton("Browse 📂")
        btn_browse_anki.clicked.connect(self.handle_browse_anki_directory)
        anki_layout.addWidget(self.line_anki_dir)
        anki_layout.addWidget(btn_browse_anki)
        
        video_layout = QHBoxLayout()
        self.line_video_dir = QLineEdit(self.video_export_dir)
        self.line_video_dir.setReadOnly(True)
        btn_browse_video = QPushButton("Browse 📂")
        btn_browse_video.clicked.connect(self.handle_browse_video_directory)
        video_layout.addWidget(self.line_video_dir)
        video_layout.addWidget(btn_browse_video)
        
        # UI Sleep Learning Configuration Fields
        self.combo_first_lang = QComboBox()
        self.combo_first_lang.addItems(["English First (en -> es)", "Spanish First (es -> en)"])
        self.combo_first_lang.setCurrentText(self.video_first_lang)
        self.combo_first_lang.currentTextChanged.connect(lambda v: self.save_setting_to_db("video_first_language", v))
        
        self.spin_video_repeats = QLineEdit(self.video_repeats_count)
        self.spin_video_repeats.setFixedWidth(60)
        self.spin_video_repeats.textChanged.connect(lambda v: self.save_setting_to_db("video_repeats_count", v))
        
        self.spin_pause_duration = QLineEdit(self.video_pause_duration)
        self.spin_pause_duration.setFixedWidth(60)
        self.spin_pause_duration.textChanged.connect(lambda v: self.save_setting_to_db("video_pause_duration", v))
        
        form_layout.addRow("<b>Anki Deck Export Destination:</b>", anki_layout)
        form_layout.addRow("<b>Video Assembly Output Target:</b>", video_layout)
        form_layout.addRow("<b>Introductory Anchor Audio Language:</b>", self.combo_first_lang)
        form_layout.addRow("<b>Target Translation Loop Multiplier (Repeats):</b>", self.spin_video_repeats)
        form_layout.addRow("<b>User Recall Repetition Frame Intermission (Seconds):</b>", self.spin_pause_duration)
        
        # High-visibility sync button to calculate missing timings and rebuild metadata cache
        self.btn_sync_cache = QPushButton("⚡ Populate Audio & Timings Cache")
        self.btn_sync_cache.setStyleSheet("""
            QPushButton { 
                font-weight: bold; 
                background-color: #e67e22; 
                color: white; 
                padding: 10px; 
                border-radius: 5px; 
                font-size: 13px;
            }
            QPushButton:hover { background-color: #d35400; }
        """)
        self.btn_sync_cache.clicked.connect(self.handle_bulk_populate_audio_cache)
        
        layout.addWidget(QLabel("<h2>Application Preferences & Workspace Routing</h2>"))
        layout.addWidget(settings_frame)
        layout.addWidget(self.btn_sync_cache)
        layout.addStretch()
        
        self.tabs.addTab(tab, "⚙️ Settings")

    def handle_browse_anki_directory(self):
        directory = QFileDialog.getExistingDirectory(self, "Select Anki Export Folder", self.anki_export_dir)
        if directory:
            self.anki_export_dir = directory
            self.line_anki_dir.setText(directory)
            self.save_setting_to_db("anki_export_directory", directory)

    def handle_browse_video_directory(self):
        directory = QFileDialog.getExistingDirectory(self, "Select Video Export Folder", self.video_export_dir)
        if directory:
            self.video_export_dir = directory
            self.line_video_dir.setText(directory)
            self.save_setting_to_db("video_export_directory", directory)

    def handle_bulk_populate_audio_cache(self):
        """Iterates through all relational links, runs dynamic downloads, analyzes audio runtime lengths via ffprobe."""
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("""
            SELECT p1.id, p1.text, p2.id, p2.text 
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            JOIN phrases p2 ON t.target_phrase_id = p2.id
        """)
        records = cursor.fetchall()
        conn.close()

        if not records:
            QMessageBox.information(self, "Cache Synchronizer", "No valid translation pairs exist inside the database to process.")
            return

        print(f"⚡ Processing structural cache updates for {len(records)} node linkages...")
        for row in records:
            es_id, es_text, en_id, en_text = row[0], row[1].strip(), row[2], row[3].strip()
            self.get_or_generate_audio_duration(en_id, en_text, "en")
            self.get_or_generate_audio_duration(es_id, es_text, "es")

        QMessageBox.information(self, "Cache Processing Complete", "All missing speech segments successfully written. Timings cached safely.")

    # =====================================================================
    # ⚡ DATA MATRIX CONTROL & SYNCHRONIZATION VIEWS
    # =====================================================================
    def refresh_crud_table(self):
        conn = get_connection()
        cursor = conn.cursor()
        
        text_filter = self.search_text_input.text().strip()
        context_filter = self.search_context_input.text().strip()
        
        query = """
            SELECT t.translation_id, p1.text, p2.text, p1.word_type, p1.source_context, t.deck_name
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            JOIN phrases p2 ON t.target_phrase_id = p2.id
            WHERE p1.language = 'es' AND p2.language = 'en'
        """
        params = []
        
        if text_filter:
            query += " AND (p1.text LIKE ? OR p2.text LIKE ?)"
            params.extend([f"%{text_filter}%", f"%{text_filter}%"])
            
        if context_filter:
            query += " AND p1.source_context LIKE ?"
            params.append(f"%{context_filter}%")
            
        query += " ORDER BY t.translation_id ASC LIMIT 250"
        
        cursor.execute(query, params)
        rows = cursor.fetchall()
        conn.close()
        
        self.translation_table.setRowCount(0)
        for row_idx, row_data in enumerate(rows):
            self.translation_table.insertRow(row_idx)
            for col_idx in range(6):
                val = row_data[col_idx]
                self.translation_table.setItem(row_idx, col_idx, QTableWidgetItem(str(val if val is not None else "")))

    def refresh_review_table(self):
        conn = get_connection()
        cursor = conn.cursor()
        
        context_filter = self.review_context_filter.text().strip()
        tag_filter = self.review_tag_filter.text().strip()
        
        query = """
            SELECT t.translation_id, p1.text, p1.source_context, t.tags, p1.id
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            WHERE p1.language = 'es'
        """
        params = []
        if context_filter:
            query += " AND p1.source_context LIKE ?"
            params.append(f"%{context_filter}%")
        if tag_filter:
            query += " AND t.tags LIKE ?"
            params.append(f"%{tag_filter}%")
            
        query += " ORDER BY t.translation_id ASC"
        
        cursor.execute(query, params)
        rows = cursor.fetchall()
        conn.close()
        
        self.review_table.setRowCount(0)
        self.flashcard_ids_pool = []
        
        for row_idx, row_data in enumerate(rows):
            self.review_table.insertRow(row_idx)
            self.flashcard_ids_pool.append(row_data[4])
            for col_idx in range(4):
                val = row_data[col_idx]
                self.review_table.setItem(row_idx, col_idx, QTableWidgetItem(str(val if val is not None else "")))

    def handle_table_row_select(self):
        selected_ranges = self.translation_table.selectedRanges()
        if not selected_ranges:
            return
        row = selected_ranges[0].topRow()
        tx_id_item = self.translation_table.item(row, 0)
        if not tx_id_item:
            return
            
        tx_id = tx_id_item.text()
        
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("""
            SELECT t.translation_id, p1.text, p2.text, p1.word_type, p1.source_context, t.deck_name, t.notes, t.tags, p1.id, p2.id
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            JOIN phrases p2 ON t.target_phrase_id = p2.id
            WHERE t.translation_id = ?
        """, (tx_id,))
        record = cursor.fetchone()
        conn.close()
        
        if record:
            self.input_tx_id.setText(str(record[0]))
            self.input_text_es.setPlainText(str(record[1]))
            self.input_text_en.setPlainText(str(record[2]))
            self.combo_type.setCurrentText(str(record[3]) if record[3] else "phrase")
            self.input_context.setText(str(record[4]) if record[4] else "")
            self.input_tags.setText(str(record[7]) if record[7] is not None else "")
            self.input_deck_tag.setText(str(record[5]) if record[5] else "General")
            self.input_grammar_note.setPlainText(str(record[6]) if record[6] is not None else "")
            self.current_sandbox_es_id = record[8]
            self.current_sandbox_en_id = record[9]

    def handle_review_table_select(self):
        selected_ranges = self.review_table.selectedRanges()
        if not selected_ranges:
            return
        row = selected_ranges[0].topRow()
        phrase_id = self.flashcard_ids_pool[row]
        self.load_flashcard_by_id(phrase_id)

    def step_table_row(self, direction):
        current_row = self.translation_table.currentRow()
        next_row = current_row + direction
        if 0 <= next_row < self.translation_table.rowCount():
            self.translation_table.setCurrentCell(next_row, 0)

    # =====================================================================
    # ➕ CRUD ENGINE ATOMIC OPERATIONS LOGIC
    # =====================================================================
    def crud_create_pair(self):
        conn = get_connection()
        cursor = conn.cursor()
        
        cursor.execute("""
            INSERT INTO phrases (text, language, word_type, source_context) VALUES (?, 'es', ?, ?)
        """, (self.input_text_es.toPlainText().strip(), self.combo_type.currentText(), self.input_context.text().strip()))
        es_id = cursor.lastrowid
        
        cursor.execute("""
            INSERT INTO phrases (text, language, word_type, source_context) VALUES (?, 'en', ?, ?)
        """, (self.input_text_en.toPlainText().strip(), self.combo_type.currentText(), self.input_context.text().strip()))
        en_id = cursor.lastrowid
        
        cursor.execute("""
            INSERT INTO translations (source_phrase_id, target_phrase_id, deck_name, notes, tags) VALUES (?, ?, ?, ?, ?)
        """, (es_id, en_id, self.input_deck_tag.text().strip() or "General", self.input_grammar_note.toPlainText().strip(), self.input_tags.text().strip()))
        
        conn.commit()
        conn.close()
        
        # Sync structural pointers instantly down to the Sandbox class variable state
        self.current_sandbox_es_id = es_id
        self.current_sandbox_en_id = en_id
        
        self.refresh_crud_table()
        self.refresh_review_table()
        QMessageBox.information(self, "Success", "Isolated phrase pairs created and relational link bound.")

    def crud_update_pair(self):
        tx_id = self.input_tx_id.text()
        if not tx_id:
            return
            
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("SELECT source_phrase_id, target_phrase_id FROM translations WHERE translation_id = ?", (tx_id,))
        ids = cursor.fetchone()
        
        if ids:
            es_id, en_id = ids
            cursor.execute("UPDATE phrases SET text=?, word_type=?, source_context=?, duration=NULL WHERE id=?", 
                           (self.input_text_es.toPlainText().strip(), self.combo_type.currentText(), self.input_context.text().strip(), es_id))
            cursor.execute("UPDATE phrases SET text=?, word_type=?, source_context=?, duration=NULL WHERE id=?", 
                           (self.input_text_en.toPlainText().strip(), self.combo_type.currentText(), self.input_context.text().strip(), en_id))
            cursor.execute("UPDATE translations SET deck_name=?, notes=?, tags=? WHERE translation_id=?", 
                           (self.input_deck_tag.text().strip() or "General", self.input_grammar_note.toPlainText().strip(), self.input_tags.text().strip(), tx_id))
            conn.commit()
            
            self.current_sandbox_es_id = es_id
            self.current_sandbox_en_id = en_id
            
        conn.close()
        self.refresh_crud_table()
        self.refresh_review_table()
        QMessageBox.information(self, "Success", "Relational node structural update complete.")

    def crud_delete_pair(self):
        tx_id = self.input_tx_id.text()
        if not tx_id:
            return
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("SELECT source_phrase_id, target_phrase_id FROM translations WHERE translation_id = ?", (tx_id,))
        ids = cursor.fetchone()
        if ids:
            es_id, en_id = ids
            cursor.execute("DELETE FROM translations WHERE translation_id=?", (tx_id,))
            cursor.execute("DELETE FROM phrases WHERE id=?", (es_id,))
            cursor.execute("DELETE FROM phrases WHERE id=?", (en_id,))
            conn.commit()
        conn.close()
        self.refresh_crud_table()
        self.refresh_review_table()
        self.input_tx_id.clear()
        self.input_text_es.clear()
        self.input_text_en.clear()
        self.input_grammar_note.clear()
        self.input_tags.clear()
        self.current_sandbox_es_id = None
        self.current_sandbox_en_id = None

    # =====================================================================
    # 🔊 AUDIO ENGINE & EXPANDED FLASHCARD ACTIONS
    # =====================================================================
    def load_flashcard_by_id(self, phrase_id):
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("""
            SELECT t.translation_id, p1.text, p1.source_context, t.deck_name, p1.id, t.tags
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            WHERE p1.id = ?
        """, (phrase_id,))
        record = cursor.fetchone()
        conn.close()
        
        if record:
            self.current_flashcard_id = record[4]
            self.lbl_card_text.setText(record[1])
            self.lbl_card_meta.setText(f"Link ID: {record[0]} • Context: {record[2]} • Tag: {record[5]} • Deck: {record[3]}")

    def handle_load_next_card(self):
        if not self.flashcard_ids_pool:
            QMessageBox.information(self, "Empty Pool", "No flashcards match your selected filter configurations.")
            return
            
        target_id = random.choice(self.flashcard_ids_pool)
        
        try:
            matched_idx = self.flashcard_ids_pool.index(target_id)
            self.review_table.setCurrentCell(matched_idx, 0)
        except ValueError:
            pass
            
        self.load_flashcard_by_id(target_id)

    def handle_play_voice(self):
        """Processes audio and calculates/caches duration via Flashcard Review pane."""
        if not self.current_flashcard_id:
            return
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("SELECT text, language FROM phrases WHERE id = ?", (self.current_flashcard_id,))
        row = cursor.fetchone()
        conn.close()
        
        if row:
            text_str, lang = row
            safe_name = "".join([c for c in text_str if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
            target_file = f"media/{safe_name}_{lang}_female.mp3"
            
            # Ensures voice is synthesized AND duration is analyzed/cached instantly
            self.get_or_generate_audio_duration(self.current_flashcard_id, text_str, lang)
            
            if os.path.exists(target_file):
                self.media_player.setSource(QUrl.fromLocalFile(os.path.abspath(target_file)))
                self.media_player.setPlaybackRate(self.slider_review_speed.value() / 100.0)
                self.media_player.play()

    def handle_flip_card(self):
        if not self.current_flashcard_id:
            return
        conn = get_connection()
        cursor = conn.cursor()
        cursor.execute("""
            SELECT p2.text, t.notes FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            JOIN phrases p2 ON t.target_phrase_id = p2.id
            WHERE p1.id = ?
        """, (self.current_flashcard_id,))
        row = cursor.fetchone()
        conn.close()
        
        if row:
            clean_es = self.lbl_card_text.text().split("\n\n👉")[0]
            display_text = f"{clean_es}\n\n👉 [ {row[0]} ]"
            if row[1]:
                display_text += f"\n\n💡 Note: {row[1]}"
            self.lbl_card_text.setText(display_text)

    def handle_sandbox_play_es(self):
        """Processes audio and calculates/caches duration via Sandbox (CRUD) Spanish Play button."""
        text_str = self.input_text_es.toPlainText().strip()
        if not text_str:
            return
        
        # Unifies behavior: forces verification tracking down to the database row item
        self.get_or_generate_audio_duration(self.current_sandbox_es_id, text_str, "es")
        safe_name = "".join([c for c in text_str if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
        target_file = f"media/{safe_name}_es_female.mp3"

        if os.path.exists(target_file):
            self.media_player.setSource(QUrl.fromLocalFile(os.path.abspath(target_file)))
            self.media_player.setPlaybackRate(float(self.combo_speed_es.currentText().replace("x", "")))
            self.media_player.play()

    def handle_sandbox_play_en(self):
        """Processes audio and calculates/caches duration via Sandbox (CRUD) English Play button."""
        text_str = self.input_text_en.toPlainText().strip()
        if not text_str:
            return
        
        # Unifies behavior: forces verification tracking down to the database row item
        self.get_or_generate_audio_duration(self.current_sandbox_en_id, text_str, "en")
        safe_name = "".join([c for c in text_str if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
        target_file = f"media/{safe_name}_en_female.mp3"

        if os.path.exists(target_file):
            self.media_player.setSource(QUrl.fromLocalFile(os.path.abspath(target_file)))
            self.media_player.setPlaybackRate(float(self.combo_speed_en.currentText().replace("x", "")))
            self.media_player.play()

    def handle_live_speed_change(self, value):
        rate = value / 100.0
        self.lbl_review_speed.setText(f"{rate:.2f}x")
        if self.media_player.playbackState() == QMediaPlayer.PlaybackState.PlayingState:
            self.media_player.setPlaybackRate(rate)

    # =====================================================================
    # 📦 ARTIFACT EXPORT GATEWAYS (GENANKI LIVE ENGINE WITH DUAL AUDIO)
    # =====================================================================
    def handle_export_anki_deck(self):
        """Compiles active subset into functional .apkg with bundled Spanish and English audio tracks."""
        if not self.flashcard_ids_pool:
            QMessageBox.warning(self, "Export Cancelled", "The current study stack is empty. Verify your search filters.")
            return

        model_hash = hashlib.sha256(b"castilian_voice_trainer_model_v2").hexdigest()
        model_id = int(model_hash[:13], 16)

        spanish_note_model = genanki.Model(
            model_id,
            'Castilian Audio Flashcard Model v2',
            fields=[
                {'name': 'SpanishPhrase'},
                {'name': 'EnglishTranslation'},
                {'name': 'GrammarNotes'},
                {'name': 'SpanishAudio'},
                {'name': 'EnglishAudio'}
            ],
            templates=[
                {
                    'name': 'Card 1: Auditory Identification',
                    'qfmt': (
                        '<div style="font-family: Arial; font-size: 24px; text-align: center; color: #2c3e50;">{{SpanishPhrase}}</div>'
                        '<br><div style="text-align: center;">{{SpanishAudio}}</div>'
                    ),
                    'afmt': (
                        '{{FrontSide}}<hr id="answer">'
                        '<div style="font-family: Arial; font-size: 20px; text-align: center; color: #27ae60; font-weight: bold;">{{EnglishTranslation}}</div>'
                        '<div style="text-align: center; margin-top: 5px;">{{EnglishAudio}}</div><br>'
                        '<div style="font-family: Arial; font-size: 14px; text-align: center; color: #7f8c8d; font-style: italic;">{{GrammarNotes}}</div>'
                    ),
                },
            ],
            css='.card { font-family: arial; font-size: 20px; text-align: center; background-color: #f8f9fa; }'
        )

        context_txt = self.review_context_filter.text().strip()
        tag_txt = self.review_tag_filter.text().strip()

        if context_txt and tag_txt:
            file_title = f"Spanish_Export_Context_{context_txt}_Tag_{tag_txt}.apkg"
        elif context_txt:
            file_title = f"Spanish_Export_Context_{context_txt}.apkg"
        elif tag_txt:
            file_title = f"Spanish_Export_Tag_{tag_txt}.apkg"
        else:
            file_title = "Spanish_Master_Deck.apkg"

        file_title = "".join([c for c in file_title if c.isalnum() or c in (".", "_", "-")]).strip()
        destination_path = os.path.join(self.anki_export_dir, file_title)

        decks_map = {}
        media_files_manifest = []

        conn = get_connection()
        cursor = conn.cursor()
        placeholders = ",".join(["?"] * len(self.flashcard_ids_pool))
        query = f"""
            SELECT t.deck_name, p1.text, p2.text, t.notes, t.tags, p1.id, p2.id
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            JOIN phrases p2 ON t.target_phrase_id = p2.id
            WHERE p1.id IN ({placeholders})
        """
        cursor.execute(query, self.flashcard_ids_pool)
        records = cursor.fetchall()
        conn.close()

        for row in records:
            db_deck_name = row[0].strip() if row[0] else "Castilian Spanish Master"
            es_text, en_text = row[1].strip(), row[2].strip()
            notes_text, tags_string = row[3].strip() if row[3] else "", row[4].strip() if row[4] else ""
            es_id, en_id = row[5], row[6]

            self.get_or_generate_audio_duration(es_id, es_text, "es")
            self.get_or_generate_audio_duration(en_id, en_text, "en")

            safe_es = "".join([c for c in es_text if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
            safe_en = "".join([c for c in en_text if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
            
            relative_es_path = f"media/{safe_es}_es_female.mp3"
            relative_en_path = f"media/{safe_en}_en_female.mp3"

            media_files_manifest.extend([relative_es_path, relative_en_path])

            if db_deck_name not in decks_map:
                deck_hash = hashlib.sha256(db_deck_name.encode('utf-8')).hexdigest()
                deck_id = int(deck_hash[:13], 16)
                decks_map[db_deck_name] = genanki.Deck(deck_id, db_deck_name)

            parsed_tags = [t for t in tags_string.replace(",", " ").split(" ") if t]
            flash_note = genanki.Note(
                model=spanish_note_model,
                fields=[es_text, en_text, notes_text, f"[sound:{safe_es}_es_female.mp3]", f"[sound:{safe_en}_en_female.mp3]"],
                tags=parsed_tags
            )
            decks_map[db_deck_name].add_note(flash_note)

        try:
            package = genanki.Package(list(decks_map.values()))
            package.media_files = [m for m in set(media_files_manifest) if os.path.exists(m)]
            package.write_to_file(destination_path)
            QMessageBox.information(self, "Export Complete", f"✨ Packaged complete!\nOutput: {file_title}")
        except Exception as export_error:
            QMessageBox.critical(self, "Export Failed", f"Genanki failure:\n{export_error}")

    # =====================================================================
    # 🎬 DYNAMIC SLEEP-LEARNING VIDEO GENERATION LAYER
    # =====================================================================
    def create_video_frame_image(self, text, output_path):
        """Renders a visual slide text frame optimized for dark sleep study rooms."""
        img = Image.new('RGB', (1920, 1080), color='#111a24')
        canvas = ImageDraw.Draw(img)
        try:
            font = ImageFont.load_default()
        except:
            font = None
            
        canvas.text((960, 540), text, fill="#e2e8f0", anchor="mm")
        img.save(output_path)

    def handle_export_video_assets(self):
        """
        Compiles filtered translation pairs into a structural sleep loop video.
        Explicitly honors all parameters from the settings table:
        1) Select first language (Self-configuring anchor)
        2) Measure dynamic anchor track duration & print frame
        3) Print target translation image & sync text timeline
        4) Wait duration for user recall repetition (Configurable intermission)
        5) Target translation sequence repeat count loop (Configurable loop index)
        """
        if not self.flashcard_ids_pool:
            QMessageBox.warning(self, "Video Generation Cancelled", "The active filter queue contains no records.")
            return

        try:
            is_english_first = "English First" in self.video_first_lang
            repeat_count = int(self.video_repeats_count) if str(self.video_repeats_count).isdigit() else 3
            pause_sec = float(self.video_pause_duration)
        except ValueError:
            QMessageBox.critical(self, "Configuration Error", "Check your settings table values for repeat multipliers and decimal pause seconds.")
            return

        temp_dir = os.path.join(os.getcwd(), "video_scratch_pad")
        os.makedirs(temp_dir, exist_ok=True)
        
        conn = get_connection()
        cursor = conn.cursor()
        placeholders = ",".join(["?"] * len(self.flashcard_ids_pool))
        query = f"""
            SELECT p1.id, p1.text, p2.id, p2.text 
            FROM translations t
            JOIN phrases p1 ON t.source_phrase_id = p1.id
            JOIN phrases p2 ON t.target_phrase_id = p2.id
            WHERE p1.id IN ({placeholders})
        """
        cursor.execute(query, self.flashcard_ids_pool)
        records = cursor.fetchall()
        conn.close()

        print(f"🎬 Compiling sleep loop timeline matching exact preferences ({self.video_first_lang}, Loops: {repeat_count}, Pause: {pause_sec}s)...")
        video_segment_paths = []

        try:
            for idx, row in enumerate(records):
                es_id, es_text = row[0], row[1].strip()
                en_id, en_text = row[2], row[3].strip()

                # 2. How we know the length: Read cached DB duration or call zero-dependency ffprobe instantly
                es_duration = self.get_or_generate_audio_duration(es_id, es_text, "es")
                en_duration = self.get_or_generate_audio_duration(en_id, en_text, "en")

                safe_es = "".join([c for c in es_text if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
                safe_en = "".join([c for c in en_text if c.isalnum() or c in (" ", "_")]).strip().replace(" ", "_").lower()
                
                es_audio_path = f"media/{safe_es}_es_female.mp3"
                en_audio_path = f"media/{safe_en}_en_female.mp3"

                # Condition 1: Evaluate selection setting matrix to establish Anchor vs Target translation flow
                if is_english_first:
                    prime_text, prime_audio, prime_dur = en_text, en_audio_path, en_duration
                    target_text, target_audio, target_dur = es_text, es_audio_path, es_duration
                else:
                    prime_text, prime_audio, prime_dur = es_text, es_audio_path, es_duration
                    target_text, target_audio, target_dur = en_text, en_audio_path, en_duration

                # Condition 2: Produce frame image with Anchor phrase and map audio file to exact track duration length
                img_prime = os.path.join(temp_dir, f"frame_prime_{idx}.png")
                self.create_video_frame_image(prime_text, img_prime)
                clip_prime_path = os.path.join(temp_dir, f"chunk_prime_{idx}.mp4")
                
                subprocess.run([
                    'ffmpeg', '-y', '-loop', '1', '-i', img_prime, '-i', prime_audio,
                    '-c:v', 'libx264', '-t', str(prime_dur), '-pix_fmt', 'yuv420p',
                    '-c:a', 'aac', '-b:a', '192k', clip_prime_path
                ], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                video_segment_paths.append(clip_prime_path)

                # Condition 3: Produce translation text slide image frame and compute matching voice track length
                img_target = os.path.join(temp_dir, f"frame_target_{idx}.png")
                self.create_video_frame_image(target_text, img_target)
                clip_target_path = os.path.join(temp_dir, f"chunk_target_{idx}.mp4")
                
                subprocess.run([
                    'ffmpeg', '-y', '-loop', '1', '-i', img_target, '-i', target_audio,
                    '-c:v', 'libx264', '-t', str(target_dur), '-pix_fmt', 'yuv420p',
                    '-c:a', 'aac', '-b:a', '192k', clip_target_path
                ], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

                # Condition 4: Structural wait time gap for user replacement repetition frame (Silent intermission video block)
                clip_silent_path = os.path.join(temp_dir, f"chunk_silent_{idx}.mp4")
                subprocess.run([
                    'ffmpeg', '-y', '-f', 'lavfi', '-i', f'color=c=#111a24:s=1920x1080:d={pause_sec}',
                    '-f', 'lavfi', '-i', 'anullsrc=cl=stereo:r=44100',
                    '-t', str(pause_sec), '-c:v', 'libx264', '-pix_fmt', 'yuv420p',
                    '-c:a', 'aac', clip_silent_path
                ], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

                # Condition 5: Loop execution cycle pattern back to Condition 3 (Repeats exact translation target X times)
                for _ in range(repeat_count):
                    video_segment_paths.append(clip_target_path)
                    video_segment_paths.append(clip_silent_path)

            if not video_segment_paths:
                QMessageBox.warning(self, "Export Error", "Timeline compilation matrix is empty.")
                return

            # --- Concat Loop: Assembly sequence processing layer ---
            manifest_path = os.path.join(temp_dir, "manifest.txt")
            with open(manifest_path, "w", encoding="utf-8") as f:
                for path in video_segment_paths:
                    f.write(f"file '{os.path.abspath(path)}'\n")

            output_file = os.path.join(self.video_export_dir, "Spanish_Sleep_Learning_Master.mp4")
            subprocess.run([
                'ffmpeg', '-y', '-f', 'concat', '-safe', '0', '-i', manifest_path,
                '-c', 'copy', output_file
            ], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            
            QMessageBox.information(self, "Success", f"Sleep Learning compilation track generated successfully!\nLocation: {output_file}")

        except Exception as e:
            QMessageBox.critical(self, "Video Synthesis Suite Error", f"Timeline compiler hit a hitch:\n{e}")
        finally:
            if os.path.exists(temp_dir):
                shutil.rmtree(temp_dir)

if __name__ == "__main__":
    print("🚀 Launching Core PyQt6 Framework Threads...")
    try:
        app = QApplication(sys.argv)
        window = SpanishTrainerApp()
        window.show()
        sys.exit(app.exec())
    except Exception as fatal_error:
        import traceback
        traceback.print_exc()
        sys.exit(1)