from __future__ import annotations

import hashlib
import re
from typing import Any
from urllib.parse import urlparse

_MXC_URL_PATTERN = re.compile(r"^mxc://([^/]+)/(.+)$")
_HTTP_URL_PATTERN = re.compile(r"^https?://")


def resolve_avatar_url(raw_url: str, homeserver: str | None = None) -> str | None:
    if not raw_url:
        return None

    if _MXC_URL_PATTERN.match(raw_url):
        return raw_url

    if _HTTP_URL_PATTERN.match(raw_url):
        if homeserver:
            return _http_to_mxc(raw_url, homeserver)
        return raw_url

    return None


def _http_to_mxc(http_url: str, homeserver: str) -> str:
    media_id = hashlib.sha256(http_url.encode()).hexdigest()[:24]

    if homeserver.startswith("http"):
        hs_domain = urlparse(homeserver).hostname or "matrix.org"
    else:
        hs_domain = homeserver

    return f"mxc://{hs_domain}/{media_id}"


def resolve_display_name(
    profile_data: dict[str, Any],
    fallback_user_id: str = "",
) -> str:
    displayname = profile_data.get("displayname", "")
    if displayname:
        return displayname.strip()

    user_id = profile_data.get("user_id", fallback_user_id)
    if user_id and user_id.startswith("@"):
        localpart = user_id[1:].split(":")[0]
        return localpart

    return user_id or "unknown"


def compare_profiles(
    current: dict[str, Any],
    incoming: dict[str, Any],
) -> dict[str, tuple[Any, Any]]:
    changes: dict[str, tuple[Any, Any]] = {}
    for key in ("displayname", "avatar_url"):
        old_val = current.get(key)
        new_val = incoming.get(key)
        if old_val != new_val:
            changes[key] = (old_val, new_val)
    return changes


def build_profile_update(
    display_name: str = "",
    avatar_url: str = "",
) -> dict[str, Any]:
    result: dict[str, Any] = {}
    if display_name:
        result["displayname"] = display_name
    if avatar_url:
        result["avatar_url"] = avatar_url
    return result


def mxc_to_http(mxc_url: str, homeserver: str) -> str:
    match = _MXC_URL_PATTERN.match(mxc_url)
    if not match:
        return mxc_url

    base = homeserver.rstrip("/")
    if not base.startswith("http"):
        base = f"https://{base}"

    server_name = match.group(1)
    media_id = match.group(2)

    return f"{base}/_matrix/media/r0/download/{server_name}/{media_id}"