from pathlib import Path

import cv2
from PIL import Image

from config import MAX_IMAGE_DIMENSIONS, MAX_VIDEO_FRAMES, MAX_VIDEO_DURATION_SEC
from managers import video_capture
from vision_utils import VideoInfo


def validate_example_files(image_paths: list[str], video_paths: dict[str, str]) -> list[str]:
    """Validate all example files exist at startup. Returns list of missing files."""
    missing = []
    for path in image_paths:
        if not Path(path).exists():
            missing.append(path)
    for path in video_paths.values():
        if not Path(path).exists():
            missing.append(path)
    return missing


def validate_image(image: Image.Image | None) -> tuple[bool, str]:
    """
    Validate image before processing.
    """
    if image is None:
        return False, "No image provided"

    width, height = image.size
    if width > MAX_IMAGE_DIMENSIONS[0] or height > MAX_IMAGE_DIMENSIONS[1]:
        return False, (
            f"Image too large ({width}x{height}). "
            f"Maximum: {MAX_IMAGE_DIMENSIONS[0]}x{MAX_IMAGE_DIMENSIONS[1]}"
        )

    return True, ""


def validate_video(video_path: str) -> tuple[bool, str, VideoInfo | None]:
    """
    Validate video file before processing, checks fps, number of frames.

    :param video_path: Path to video
    :return: Tuple of: is_valid flag, error message, and video information
    """
    with video_capture(video_path) as cap:
        if not cap.isOpened():
            return False, "Could not open video file.", None

        fps = cap.get(cv2.CAP_PROP_FPS)
        total_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
        width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
        video_info = VideoInfo(fps=fps, total_frames=total_frames, width=width, height=height)

        if fps < 0 or fps > 240:
            return False, f"Invalid video fps: {fps}.", video_info
        if total_frames <= 0:
            return False, "Video has no frames.", video_info
        if width <= 0 or height <= 0:
            return False, f"Invalid dimensions: {width}x{height}.", video_info
        if total_frames > MAX_VIDEO_FRAMES:
            return False, (
                f"Video too long ({total_frames} frames). "
                f"Maximum: {MAX_VIDEO_FRAMES} frames (~{MAX_VIDEO_DURATION_SEC}s at 30FPS)"
            ), video_info

        return True, "", video_info