"""Helpers for social post media (StoredFile-backed)."""

from __future__ import annotations

import json
from typing import Any

from django.conf import settings
from django.urls import reverse

from core.models import StoredFile

ALLOWED_IMAGE_TYPES = frozenset(
    {"image/jpeg", "image/jpg", "image/png", "image/gif", "image/webp"}
)
ALLOWED_VIDEO_TYPES = frozenset(
    {"video/mp4", "video/quicktime", "video/webm"}
)
MAX_IMAGE_BYTES = 8 * 1024 * 1024  # 8 MB
MAX_VIDEO_BYTES = 100 * 1024 * 1024  # 100 MB
MAX_IMAGES = 10


def public_file_url(file_id: str) -> str:
    """Absolute URL Meta/LinkedIn can fetch (UUID = capability token)."""
    base = (settings.PUBLIC_SITE_URL or "").rstrip("/")
    path = reverse("core:stored_file", kwargs={"pk": file_id})
    if not base:
        return path
    return f"{base}{path}"


def media_item_from_stored(stored: StoredFile) -> dict[str, Any]:
    kind = stored.kind
    media_type = "video" if kind == StoredFile.Kind.SOCIAL_VIDEO else "image"
    return {
        "id": str(stored.pk),
        "type": media_type,
        "url": public_file_url(str(stored.pk)),
        "content_type": stored.content_type,
        "filename": stored.filename or "",
        "size": stored.size,
    }


def parse_media_json(raw: str) -> list[dict[str, Any]]:
    """Parse composer hidden media JSON into a cleaned list."""
    raw = (raw or "").strip()
    if not raw:
        return []
    try:
        data = json.loads(raw)
    except json.JSONDecodeError as exc:
        raise ValueError("Invalid media payload.") from exc
    if not isinstance(data, list):
        raise ValueError("Media payload must be a list.")

    items: list[dict[str, Any]] = []
    for entry in data:
        if not isinstance(entry, dict):
            continue
        file_id = str(entry.get("id") or "").strip()
        if not file_id:
            continue
        try:
            stored = StoredFile.objects.get(pk=file_id)
        except (StoredFile.DoesNotExist, ValueError) as exc:
            raise ValueError(f"Unknown media file: {file_id}") from exc
        if stored.kind not in {
            StoredFile.Kind.SOCIAL_IMAGE,
            StoredFile.Kind.SOCIAL_VIDEO,
            StoredFile.Kind.CAMPAIGN_IMAGE,
        }:
            raise ValueError("File is not a social media attachment.")
        items.append(media_item_from_stored(stored))

    videos = [m for m in items if m["type"] == "video"]
    images = [m for m in items if m["type"] == "image"]
    if len(videos) > 1:
        raise ValueError("Attach at most one video per post.")
    if videos and images:
        raise ValueError("Use either images or one video — not both.")
    if len(images) > MAX_IMAGES:
        raise ValueError(f"Attach at most {MAX_IMAGES} images.")
    return items


def split_media(media: list[dict[str, Any]]) -> tuple[list[dict], list[dict]]:
    images = [m for m in media if m.get("type") == "image"]
    videos = [m for m in media if m.get("type") == "video"]
    return images, videos