import os
from PyQt6.QtWidgets import (QMainWindow, QWidget, QVBoxLayout, QHBoxLayout, 
                             QTreeWidget, QTreeWidgetItem, QFileDialog, QMenuBar, QMenu, QMessageBox)
from PyQt6.QtGui import QAction, QKeyEvent
from PyQt6.QtCore import Qt

from .io import load_t42, save_t42
from .renderer import TeletextCanvas
from .models import TeletextService, Page, Packet

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Teletext Editor")
        self.resize(1024, 768)
        
        self.service = TeletextService()
        self.current_page: Page = None
        
        # UI Components
        self.central_widget = QWidget()
        self.setCentralWidget(self.central_widget)
        
        self.layout = QHBoxLayout(self.central_widget)
        
        # Left Panel: Page Tree
        self.tree = QTreeWidget()
        self.tree.setHeaderLabel("Pages")
        self.tree.setFixedWidth(200)
        self.tree.itemClicked.connect(self.on_page_selected)
        self.layout.addWidget(self.tree)
        
        # Center: Teletext Canvas
        self.canvas = TeletextCanvas()
        self.layout.addWidget(self.canvas, 1) # Expand
        
        # Menus
        self.create_menus()
        
    def create_menus(self):
        menu_bar = self.menuBar()
        
        file_menu = menu_bar.addMenu("File")
        
        open_action = QAction("Open T42...", self)
        open_action.triggered.connect(self.open_file)
        file_menu.addAction(open_action)
        
        save_action = QAction("Save T42...", self)
        save_action.triggered.connect(self.save_file)
        file_menu.addAction(save_action)
        
        exit_action = QAction("Exit", self)
        exit_action.triggered.connect(self.close)
        file_menu.addAction(exit_action)
        
        view_menu = menu_bar.addMenu("View")
        
        lang_menu = view_menu.addMenu("Language")
        langs = ["English", "German", "Swedish/Finnish", "Italian", "French", "Portuguese/Spanish", "Turkish", "Romania"]
        for i, lang in enumerate(langs):
            action = QAction(lang, self)
            action.setData(i)
            action.triggered.connect(self.set_language)
            lang_menu.addAction(action)

    def set_language(self):
        action = self.sender()
        if action:
            idx = action.data()
            self.canvas.subset_idx = idx
            self.canvas.redraw()
            self.canvas.update()

    def open_file(self):
        fname, _ = QFileDialog.getOpenFileName(self, "Open T42", "", "Teletext Files (*.t42);;All Files (*)")
        if fname:
            try:
                self.service = load_t42(fname)
                self.populate_tree()
                QMessageBox.information(self, "Loaded", f"Loaded {len(self.service.pages)} pages.")
            except Exception as e:
                QMessageBox.critical(self, "Error", f"Failed to load file: {e}")

    def save_file(self):
        fname, _ = QFileDialog.getSaveFileName(self, "Save T42", "", "Teletext Files (*.t42);;All Files (*)")
        if fname:
            try:
                save_t42(fname, self.service)
                QMessageBox.information(self, "Saved", "File saved successfully.")
            except Exception as e:
                QMessageBox.critical(self, "Error", f"Failed to save file: {e}")

    def populate_tree(self):
        self.tree.clear()
        
        # Group by Magazine
        mags = {}
        for p in self.service.pages:
            if p.magazine not in mags:
                mags[p.magazine] = QTreeWidgetItem([f"Magazine {p.magazine}"])
                self.tree.addTopLevelItem(mags[p.magazine])
            
            # Format: PPP-SS (Page-Subcode)
            # Create Item
            # Subcode is complicated to display "nicely" without decoding, 
            # let's just show hex or raw for now if not standard 0000.
            
            label = f"{p.page_number:02d} (Sub: {p.sub_code:04X})"
            item = QTreeWidgetItem([label])
            item.setData(0, Qt.ItemDataRole.UserRole, p)
            mags[p.magazine].addChild(item)
            
        self.tree.expandAll()

    def on_page_selected(self, item, column):
        page = item.data(0, Qt.ItemDataRole.UserRole)
        if isinstance(page, Page):
            self.current_page = page
            self.canvas.set_page(page)
            # Also set window focus to canvas or handle key events?
            self.canvas.setFocus()
            
    # Input Handling (Editor Logic)
    def keyPressEvent(self, event: QKeyEvent):
        if not self.current_page:
            return
            
        key = event.key()
        text = event.text()
        
        # Navigation
        if key == Qt.Key.Key_Up:
            self.canvas.move_cursor(0, -1)
        elif key == Qt.Key.Key_Down:
            self.canvas.move_cursor(0, 1)
        elif key == Qt.Key.Key_Left:
            self.canvas.move_cursor(-1, 0)
        elif key == Qt.Key.Key_Right:
            self.canvas.move_cursor(1, 0)
        else:
            # Typing
            # Filter non-printable
            if text and len(text) == 1 and 32 <= ord(text) <= 126:
                self.canvas.handle_input(text)
            elif key == Qt.Key.Key_Backspace:
                # Move back and delete
                self.canvas.move_cursor(-1, 0)
                self.canvas.handle_input(' ')
                self.canvas.move_cursor(-1, 0) # Compensate for the auto-advance logic if any