"""
Service de stockage — sauvegarde fichiers, génération thumbnails
Multi-tenant : les fichiers sont isolés par client_id.
"""
import uuid
import logging
import aiofiles
from pathlib import Path
from datetime import datetime, timezone
from PIL import Image as PILImage
from fastapi import UploadFile, HTTPException, status
from app.config import settings

logger = logging.getLogger(__name__)

ALLOWED_MIME_TYPES = {
    "image/jpeg", "image/png", "image/gif",
    "image/webp", "image/bmp", "image/tiff",
}

THUMBNAIL_SIZE = (320, 320)


def _generate_filename(original: str) -> tuple[str, str]:
    """Retourne (uuid_filename, extension)."""
    suffix = Path(original).suffix.lower() or ".jpg"
    uid = str(uuid.uuid4())
    return f"{uid}{suffix}", uid


def _get_client_upload_path(client_id: str) -> Path:
    """Retourne le répertoire d'upload pour un client donné."""
    p = settings.upload_path / client_id
    p.mkdir(parents=True, exist_ok=True)
    return p


def _get_client_thumbnails_path(client_id: str) -> Path:
    """Retourne le répertoire de thumbnails pour un client donné."""
    p = settings.thumbnails_path / client_id
    p.mkdir(parents=True, exist_ok=True)
    return p


async def save_upload(file: UploadFile, client_id: str) -> dict:
    """
    Valide, sauvegarde le fichier uploadé et génère un thumbnail.
    Les fichiers sont stockés dans uploads/{client_id}/ pour l'isolation.
    Retourne un dict avec toutes les métadonnées fichier.
    """
    # ── Validation MIME ───────────────────────────────────────
    if file.content_type not in ALLOWED_MIME_TYPES:
        raise HTTPException(
            status_code=status.HTTP_415_UNSUPPORTED_MEDIA_TYPE,
            detail=f"Type non supporté : {file.content_type}. "
                   f"Acceptés : {', '.join(ALLOWED_MIME_TYPES)}",
        )

    # ── Lecture du contenu ────────────────────────────────────
    content = await file.read()

    if len(content) > settings.max_upload_bytes:
        raise HTTPException(
            status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
            detail=f"Fichier trop volumineux. Max : {settings.MAX_UPLOAD_SIZE_MB} MB",
        )

    # ── Nommage et chemins ────────────────────────────────────
    filename, file_uuid = _generate_filename(file.filename or "image")
    upload_dir = _get_client_upload_path(client_id)
    thumb_dir = _get_client_thumbnails_path(client_id)

    file_path = upload_dir / filename
    thumb_filename = f"thumb_{filename}"
    thumb_path = thumb_dir / thumb_filename

    # ── Sauvegarde fichier original ───────────────────────────
    async with aiofiles.open(file_path, "wb") as f:
        await f.write(content)

    # ── Dimensions + thumbnail ────────────────────────────────
    width, height = None, None
    try:
        with PILImage.open(file_path) as img:
            width, height = img.size
            img.thumbnail(THUMBNAIL_SIZE, PILImage.LANCZOS)
            # Convertit en RGB si nécessaire (ex: PNG RGBA)
            if img.mode in ("RGBA", "P"):
                img = img.convert("RGB")
            img.save(thumb_path, "JPEG", quality=85)
    except Exception as e:
        # Thumbnail non bloquant
        thumb_path = None
        logger.warning("Erreur génération thumbnail : %s", e)

    return {
        "uuid": file_uuid,
        "original_name": file.filename,
        "filename": filename,
        "file_path": str(file_path),
        "thumbnail_path": str(thumb_path) if thumb_path else None,
        "mime_type": file.content_type,
        "file_size": len(content),
        "width": width,
        "height": height,
        "uploaded_at": datetime.now(timezone.utc),
        "client_id": client_id,
    }


def delete_files(file_path: str, thumbnail_path: str | None = None) -> None:
    """Supprime le fichier original et son thumbnail du disque."""
    for path_str in [file_path, thumbnail_path]:
        if path_str:
            p = Path(path_str)
            if p.exists():
                p.unlink()


def get_image_url(filename: str, client_id: str, thumb: bool = False) -> str:
    """Construit l'URL publique d'une image."""
    prefix = "thumbnails" if thumb else "uploads"
    return f"/static/{prefix}/{client_id}/{filename}"