// Playlists: local + YouTube-linked, item add/remove/reorder, the built-in Watch later shortcut,
// and the push-to-YouTube plan/apply flow. Only touches core's req.
import { req } from "./core";
import type { Video } from "./feed";

// Not exported: consumers compare `playlist.kind`/`.source` against string literals, they never
// name these types — keeping them local satisfies the no-unused-exports gate (knip).
type PlaylistKind = "user" | "watch_later";
type PlaylistSource = "local" | "youtube";

export interface Playlist {
  id: number;
  name: string;
  kind: PlaylistKind;
  source: PlaylistSource;
  yt_playlist_id: string | null;
  dirty: boolean; // linked local playlist has edits not yet pushed to YouTube
  item_count: number;
  total_duration_seconds: number;
  cover_thumbnail: string | null;
  has_video?: boolean; // only set when listed with ?contains=<video_id>
}

export interface PlaylistDetail {
  id: number;
  name: string;
  kind: PlaylistKind;
  source: PlaylistSource;
  yt_playlist_id: string | null;
  dirty: boolean;
  items: Video[];
}

// Two-way sync plan: what each side gains/loses under the 3-way merge (neither side wins
// wholesale). Local edits are free; only the YouTube writes cost quota.
export interface PushPlan {
  action: "create" | "update";
  add_yt: number; // local-adds to push out to YouTube
  add_local: number; // YouTube-adds to pull into Siftlode
  remove_yt: number; // genuine local deletes propagated to YouTube
  remove_local: number; // genuine YouTube deletes propagated to Siftlode
  to_reorder: number;
  rename: boolean;
  units_estimate: number;
  remaining_today: number;
  affordable: boolean;
}

export interface PushResult {
  created: number;
  inserted: number; // added on YouTube
  deleted: number; // removed on YouTube
  reordered: number;
  pulled: number; // added into Siftlode from YouTube
  removed_local: number; // removed from Siftlode (deleted on YouTube)
  failures: string[];
  yt_playlist_id: string | null;
}

export const playlistsApi = {
  playlists: (containsVideoId?: string): Promise<Playlist[]> =>
    req(`/api/playlists${containsVideoId ? `?contains=${containsVideoId}` : ""}`),
  playlist: (id: number): Promise<PlaylistDetail> => req(`/api/playlists/${id}`),
  createPlaylist: (name: string): Promise<Playlist> =>
    req("/api/playlists", { method: "POST", body: JSON.stringify({ name }) }),
  renamePlaylist: (id: number, name: string): Promise<Playlist> =>
    req(`/api/playlists/${id}`, { method: "PATCH", body: JSON.stringify({ name }) }),
  deletePlaylist: (id: number, onYoutube = false) =>
    req(`/api/playlists/${id}${onYoutube ? "?on_youtube=true" : ""}`, { method: "DELETE" }),
  addToPlaylist: (id: number, videoId: string) =>
    req(`/api/playlists/${id}/items`, {
      method: "POST",
      body: JSON.stringify({ video_id: videoId }),
    }),
  removeFromPlaylist: (id: number, videoId: string) =>
    req(`/api/playlists/${id}/items/${videoId}`, { method: "DELETE" }),
  reorderPlaylist: (id: number, videoIds: string[]) =>
    req(`/api/playlists/${id}/order`, {
      method: "PUT",
      body: JSON.stringify({ video_ids: videoIds }),
    }),
  // Bookmark shortcut for the built-in Watch later playlist.
  watchLaterAdd: (videoId: string) =>
    req("/api/playlists/watch-later", {
      method: "POST",
      body: JSON.stringify({ video_id: videoId }),
    }),
  watchLaterRemove: (videoId: string) =>
    req(`/api/playlists/watch-later/${videoId}`, { method: "DELETE" }),
  syncYoutubePlaylists: (): Promise<{ synced: number; reason?: string }> =>
    req("/api/playlists/sync-youtube", { method: "POST" }),
  revertPlaylist: (id: number): Promise<{ items: number }> =>
    req(`/api/playlists/${id}/revert-youtube`, { method: "POST" }),
  playlistPushPlan: (id: number): Promise<PushPlan> => req(`/api/playlists/${id}/push-plan`),
  pushPlaylist: (id: number): Promise<PushResult> =>
    req(`/api/playlists/${id}/push`, { method: "POST" }),
};