"""Character portraits: a small square picture stored inside the character as a data URL (so it travels with saving, sharing and
loading). The browser crops it to a square; the server checks and re-encodes it (256 px, WebP) so only real images get stored."""
import base64
import binascii
import hashlib
import io

from fastapi import HTTPException
from PIL import Image, ImageOps

SIZE = 256
MAX_RAW = 400_000  # bytes of the uploaded data before re-encoding


def clean(ch: dict) -> None:
    """Validates and re-encodes ch["portrait"] in place (an empty value removes it)."""
    p = ch.get("portrait")
    if not p:
        ch["portrait"] = ""
        return
    if not isinstance(p, str) or not p.startswith("data:image/") or ";base64," not in p:
        raise HTTPException(422, "The portrait must be an image")
    try:
        raw = base64.b64decode(p.split(";base64,", 1)[1], validate=True)
        if len(raw) > MAX_RAW:
            raise HTTPException(413, "The portrait is too large")
        im = Image.open(io.BytesIO(raw))
        if im.format not in ("PNG", "JPEG", "WEBP"):
            raise ValueError
        im.load()
    except HTTPException:
        raise
    except (binascii.Error, ValueError, OSError, Image.DecompressionBombError):
        raise HTTPException(422, "The portrait must be a PNG, JPEG or WebP image")
    im = ImageOps.fit(ImageOps.exif_transpose(im).convert("RGB"), (SIZE, SIZE))
    out = io.BytesIO()
    im.save(out, "WEBP", quality=85)
    ch["portrait"] = "data:image/webp;base64," + base64.b64encode(out.getvalue()).decode()


def tag(portrait) -> str:
    """Short fingerprint, used as cache key in URLs ("" if there is no portrait)."""
    return hashlib.sha1(portrait.encode()).hexdigest()[:10] if portrait else ""


def image(portrait) -> bytes | None:
    if not portrait or ";base64," not in portrait:
        return None
    try:
        return base64.b64decode(portrait.split(";base64,", 1)[1])
    except (binascii.Error, ValueError):
        return None