from __future__ import annotations

import mimetypes
import re
from datetime import UTC, datetime
from pathlib import Path

from core.protocol import Attachment


def _sanitize_component(value: str) -> str:
    cleaned = re.sub(r"[^A-Za-z0-9._-]+", "_", value)
    cleaned = cleaned.strip("._-")
    return cleaned or "unknown"


def _default_filename(attachment: Attachment) -> str:
    if attachment.filename:
        return attachment.filename

    extension = mimetypes.guess_extension(attachment.mime_type or "") or ""
    base = {
        "image": "image",
        "audio": "audio",
        "video": "video",
        "document": "attachment",
    }.get(attachment.type, "attachment")
    return f"{base}{extension}"


def build_workspace_attachment_path(
    *,
    workspace_root: Path,
    matrix_user_id: str,
    room_id: str,
    filename: str,
    timestamp: str | None = None,
) -> tuple[str, Path]:
    stamp = timestamp or datetime.now(UTC).strftime("%Y%m%d-%H%M%S")
    safe_user = _sanitize_component(matrix_user_id.lstrip("@"))
    safe_room = _sanitize_component(room_id.lstrip("!"))
    safe_name = _sanitize_component(filename) or "attachment.bin"
    relative_path = (
        Path("surfaces") / "matrix" / safe_user / safe_room / "inbox" / f"{stamp}-{safe_name}"
    )
    return relative_path.as_posix(), workspace_root / relative_path


async def download_matrix_attachment(
    *,
    client,
    workspace_root: Path,
    matrix_user_id: str,
    room_id: str,
    attachment: Attachment,
    timestamp: str | None = None,
) -> Attachment:
    if not attachment.url:
        return attachment

    filename = _default_filename(attachment)
    relative_path, absolute_path = build_workspace_attachment_path(
        workspace_root=workspace_root,
        matrix_user_id=matrix_user_id,
        room_id=room_id,
        filename=filename,
        timestamp=timestamp,
    )
    absolute_path.parent.mkdir(parents=True, exist_ok=True)

    response = await client.download(attachment.url)
    body = getattr(response, "body", None)
    if body is None:
        raise RuntimeError(f"Matrix download response for {attachment.url} has no body")
    absolute_path.write_bytes(body)

    return Attachment(
        type=attachment.type,
        url=attachment.url,
        filename=filename,
        mime_type=attachment.mime_type,
        workspace_path=relative_path,
    )


def resolve_workspace_attachment_path(workspace_root: Path, workspace_path: str) -> Path:
    path = Path(workspace_path)
    if path.is_absolute():
        return path
    return workspace_root / path


def matrix_msgtype_for_attachment(attachment: Attachment) -> str:
    return {
        "image": "m.image",
        "audio": "m.audio",
        "video": "m.video",
    }.get(attachment.type, "m.file")