"""
Полноэкранный просмотрщик изображений.
Стрелки ←/→ — листание, Esc / двойной клик — выход, колесо мыши — листание.
"""

import logging
from typing import List

from PyQt6.QtWidgets import QWidget, QVBoxLayout, QLabel
from PyQt6.QtGui import QPixmap, QKeyEvent
from PyQt6.QtCore import Qt

logger = logging.getLogger(__name__)


class FullscreenViewer(QWidget):
    def __init__(self, filepaths: List[str], start_index: int = 0, parent=None):
        super().__init__(parent)
        self.filepaths = filepaths
        self.index = max(0, min(start_index, len(filepaths) - 1))

        self.setWindowFlags(Qt.WindowType.Window | Qt.WindowType.FramelessWindowHint)
        self.setStyleSheet("background-color: #000000;")

        layout = QVBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)

        self.image_label = QLabel()
        self.image_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
        self.image_label.setStyleSheet("background-color: #000000;")
        layout.addWidget(self.image_label, 1)

        self.info_label = QLabel()
        self.info_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
        self.info_label.setStyleSheet(
            "color: #9e9e9e; background-color: #000000; padding: 6px; font-size: 12px;")
        layout.addWidget(self.info_label)

        self._current_pixmap = None

    def open_fullscreen(self):
        self.showFullScreen()
        self._load_current()

    def _load_current(self):
        if not self.filepaths:
            return
        path = self.filepaths[self.index]
        pixmap = QPixmap(path)
        if pixmap.isNull():
            self.image_label.setText("⚠")
            self._current_pixmap = None
        else:
            self._current_pixmap = pixmap
            self._rescale()
        self.info_label.setText(f"{self.index + 1} / {len(self.filepaths)}  —  {path}")

    def _rescale(self):
        if self._current_pixmap:
            scaled = self._current_pixmap.scaled(
                self.image_label.size(),
                Qt.AspectRatioMode.KeepAspectRatio,
                Qt.TransformationMode.SmoothTransformation
            )
            self.image_label.setPixmap(scaled)

    def resizeEvent(self, event):
        self._rescale()
        super().resizeEvent(event)

    def keyPressEvent(self, event: QKeyEvent):
        key = event.key()
        if key == Qt.Key.Key_Escape:
            self.close()
        elif key in (Qt.Key.Key_Right, Qt.Key.Key_Down, Qt.Key.Key_Space):
            self._next()
        elif key in (Qt.Key.Key_Left, Qt.Key.Key_Up):
            self._prev()
        else:
            super().keyPressEvent(event)

    def wheelEvent(self, event):
        if event.angleDelta().y() < 0:
            self._next()
        else:
            self._prev()

    def mouseDoubleClickEvent(self, event):
        self.close()

    def _next(self):
        if self.index < len(self.filepaths) - 1:
            self.index += 1
            self._load_current()

    def _prev(self):
        if self.index > 0:
            self.index -= 1
            self._load_current()