#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from __future__ import annotations

import os
from datetime import datetime
from typing import Iterator

import database
from app_config import get_config
from app_security import is_safe_path
from flask import Blueprint, jsonify, send_from_directory
from flask_login import current_user, login_required
from PIL import Image, ImageOps
from services.client_log import log_to_client
from services.time_utils import BEIJING_TZ

config = get_config()
SCREENSHOTS_DIR = config.SCREENSHOTS_DIR
_IMAGE_EXTENSIONS = (".png", ".jpg", ".jpeg")
_THUMBNAIL_DIR = os.path.join(SCREENSHOTS_DIR, ".thumbs")
_THUMBNAIL_MAX_SIZE = (480, 270)
_THUMBNAIL_QUALITY = 80

try:
    _RESAMPLE_FILTER = Image.Resampling.LANCZOS
except AttributeError:  # Pillow<9 fallback
    _RESAMPLE_FILTER = Image.LANCZOS

api_screenshots_bp = Blueprint("api_screenshots", __name__)


def _get_user_prefix(user_id: int) -> str:
    user_info = database.get_user_by_id(user_id)
    return user_info["username"] if user_info else f"user{user_id}"


def _is_user_screenshot(filename: str, username_prefix: str) -> bool:
    return filename.startswith(username_prefix + "_") and filename.lower().endswith(_IMAGE_EXTENSIONS)


def _iter_user_screenshot_entries(username_prefix: str) -> Iterator[os.DirEntry]:
    if not os.path.exists(SCREENSHOTS_DIR):
        return

    with os.scandir(SCREENSHOTS_DIR) as entries:
        for entry in entries:
            if (not entry.is_file()) or (not _is_user_screenshot(entry.name, username_prefix)):
                continue
            yield entry


def _build_display_name(filename: str) -> str:
    base_name, ext = filename.rsplit(".", 1)
    parts = base_name.split("_", 1)
    if len(parts) > 1:
        return f"{parts[1]}.{ext}"
    return filename


def _thumbnail_name(filename: str) -> str:
    stem, _ = os.path.splitext(filename)
    return f"{stem}.thumb.jpg"


def _thumbnail_path(filename: str) -> str:
    return os.path.join(_THUMBNAIL_DIR, _thumbnail_name(filename))


def _ensure_thumbnail(source_path: str, thumb_path: str) -> bool:
    if not os.path.exists(source_path):
        return False

    source_mtime = os.path.getmtime(source_path)
    if os.path.exists(thumb_path) and os.path.getmtime(thumb_path) >= source_mtime:
        return True

    os.makedirs(_THUMBNAIL_DIR, exist_ok=True)

    with Image.open(source_path) as image:
        image = ImageOps.exif_transpose(image)
        if image.mode != "RGB":
            image = image.convert("RGB")
        image.thumbnail(_THUMBNAIL_MAX_SIZE, _RESAMPLE_FILTER)
        image.save(
            thumb_path,
            format="JPEG",
            quality=_THUMBNAIL_QUALITY,
            optimize=True,
            progressive=True,
        )

    os.utime(thumb_path, (source_mtime, source_mtime))
    return True


def _remove_thumbnail(filename: str) -> None:
    thumb_path = _thumbnail_path(filename)
    if os.path.exists(thumb_path):
        os.remove(thumb_path)


@api_screenshots_bp.route("/api/screenshots", methods=["GET"])
@login_required
def get_screenshots():
    """获取当前用户的截图列表"""
    user_id = current_user.id
    username_prefix = _get_user_prefix(user_id)

    try:
        screenshots = []
        for entry in _iter_user_screenshot_entries(username_prefix):
            filename = entry.name
            stat = entry.stat()
            created_time = datetime.fromtimestamp(stat.st_mtime, tz=BEIJING_TZ)

            screenshots.append(
                {
                    "filename": filename,
                    "display_name": _build_display_name(filename),
                    "size": stat.st_size,
                    "created": created_time.strftime("%Y-%m-%d %H:%M:%S"),
                    "_created_ts": stat.st_mtime,
                }
            )

        screenshots.sort(key=lambda item: item.get("_created_ts", 0), reverse=True)
        for item in screenshots:
            item.pop("_created_ts", None)

        return jsonify(screenshots)
    except Exception as e:
        return jsonify({"error": str(e)}), 500


@api_screenshots_bp.route("/screenshots/<filename>")
@login_required
def serve_screenshot(filename):
    """提供原图文件访问"""
    user_id = current_user.id
    username_prefix = _get_user_prefix(user_id)

    if not _is_user_screenshot(filename, username_prefix):
        return jsonify({"error": "无权访问"}), 403

    if not is_safe_path(SCREENSHOTS_DIR, filename):
        return jsonify({"error": "非法路径"}), 403

    return send_from_directory(SCREENSHOTS_DIR, filename)


@api_screenshots_bp.route("/screenshots/thumb/<filename>")
@login_required
def serve_screenshot_thumbnail(filename):
    """提供缩略图访问（失败时自动回退原图）"""
    user_id = current_user.id
    username_prefix = _get_user_prefix(user_id)

    if not _is_user_screenshot(filename, username_prefix):
        return jsonify({"error": "无权访问"}), 403

    if not is_safe_path(SCREENSHOTS_DIR, filename):
        return jsonify({"error": "非法路径"}), 403

    source_path = os.path.join(SCREENSHOTS_DIR, filename)
    if not os.path.exists(source_path):
        return jsonify({"error": "文件不存在"}), 404

    thumb_path = _thumbnail_path(filename)

    try:
        if _ensure_thumbnail(source_path, thumb_path) and os.path.exists(thumb_path):
            return send_from_directory(_THUMBNAIL_DIR, os.path.basename(thumb_path), max_age=86400, conditional=True)
    except Exception:
        pass

    return send_from_directory(SCREENSHOTS_DIR, filename, max_age=3600, conditional=True)


@api_screenshots_bp.route("/api/screenshots/<filename>", methods=["DELETE"])
@login_required
def delete_screenshot(filename):
    """删除指定截图"""
    user_id = current_user.id
    username_prefix = _get_user_prefix(user_id)

    if not _is_user_screenshot(filename, username_prefix):
        return jsonify({"error": "无权删除"}), 403

    if not is_safe_path(SCREENSHOTS_DIR, filename):
        return jsonify({"error": "非法路径"}), 403

    try:
        filepath = os.path.join(SCREENSHOTS_DIR, filename)
        if os.path.exists(filepath):
            os.remove(filepath)
            _remove_thumbnail(filename)
            log_to_client(f"删除截图: {filename}", user_id)
            return jsonify({"success": True})
        return jsonify({"error": "文件不存在"}), 404
    except Exception as e:
        return jsonify({"error": str(e)}), 500


@api_screenshots_bp.route("/api/screenshots/clear", methods=["POST"])
@login_required
def clear_all_screenshots():
    """清空当前用户的所有截图"""
    user_id = current_user.id
    username_prefix = _get_user_prefix(user_id)

    try:
        deleted_count = 0
        for entry in _iter_user_screenshot_entries(username_prefix):
            os.remove(entry.path)
            _remove_thumbnail(entry.name)
            deleted_count += 1

        log_to_client(f"清理了 {deleted_count} 个截图文件", user_id)
        return jsonify({"success": True, "deleted": deleted_count})
    except Exception as e:
        return jsonify({"error": str(e)}), 500