"""
Screenshot / image utility functions.
"""

from __future__ import annotations

import base64
import io
from pathlib import Path
from typing import Tuple, Union

from PIL import Image


def load_image(path: Union[str, Path]) -> Image.Image:
    """
    Load an image from a filesystem path.

    Args:
        path: Absolute or relative path to the image file.

    Returns:
        PIL.Image in RGB mode.

    Raises:
        FileNotFoundError: If the file does not exist.
        IOError: If the file cannot be opened as an image.
    """
    path = Path(path)
    if not path.exists():
        raise FileNotFoundError(f"Image not found: {path}")
    return Image.open(path).convert("RGB")


def save_image(img: Image.Image, path: Union[str, Path]) -> None:
    """
    Save a PIL.Image to a filesystem path, creating parent directories as needed.

    Args:
        img: PIL.Image to save.
        path: Destination file path (.png, .jpg, etc.).
    """
    path = Path(path)
    path.parent.mkdir(parents=True, exist_ok=True)
    img.save(str(path))


def resize_image(
    img: Image.Image,
    target_size: Tuple[int, int] = (1280, 720),
) -> Image.Image:
    """
    Resize an image to the target (width, height) using Lanczos resampling.

    Args:
        img: Input PIL.Image.
        target_size: (width, height) tuple.

    Returns:
        Resized PIL.Image.
    """
    if img.size == target_size:
        return img
    return img.resize(target_size, Image.LANCZOS)


def base64_to_image(b64_str: str) -> Image.Image:
    """
    Decode a base64-encoded image string to a PIL.Image.

    Args:
        b64_str: Base64 string (with or without data URI prefix).

    Returns:
        PIL.Image in RGB mode.
    """
    # Strip data URI prefix if present, e.g. "data:image/png;base64,..."
    if "," in b64_str:
        b64_str = b64_str.split(",", 1)[1]

    data = base64.b64decode(b64_str)
    return Image.open(io.BytesIO(data)).convert("RGB")


def image_to_base64(img: Image.Image, fmt: str = "PNG") -> str:
    """
    Encode a PIL.Image to a base64 string.

    Args:
        img: Input PIL.Image.
        fmt: Image format for encoding (default: "PNG").

    Returns:
        Base64-encoded string (no data URI prefix).
    """
    buf = io.BytesIO()
    img.save(buf, format=fmt)
    buf.seek(0)
    return base64.b64encode(buf.read()).decode("utf-8")