import type { Platform } from "./platform";
import { pageFileName } from "./manifest";
import type { VideoState } from "./availability";

// Bumping this invalidates the LMDB `statsByPath` incremental cache and forces
// a full re-extraction (e.g. when a new field is added below). It versions the
// CACHE, not the published pages: STATS_MANIFEST_VERSION is theirs.
//   6 — the cache key gained the index's transcript record, and a transcript
//       always has a `transcribedDate` (caption videos: the VTT's arrival).
//       The page shape did not change.
export const STATS_SCHEMA_VERSION = 6;
export const STATS_MANIFEST_VERSION = 1;

// A key in buildIndex's `meta` sub-DB (not this cache's): the ms timestamp the
// last COMPLETED index build's scan began at. buildIndex writes it; buildStats
// reads it to tell a video downloaded since that scan from one the scan saw and
// did not index. Here rather than in buildIndex.ts so buildStats need not load
// the index builder. Additive: the index schema did not move.
export const INDEX_SCANNED_AT_KEY = "scannedAt";

// Visibility of a video on its source platform. One type with the viewer's, so
// the status chart and the search filter can never drift apart; see VideoState
// in lib/availability for the taxonomy (available + the five missing leaves).
export type VideoStatus = VideoState;

// Coarse media kind. YouTube distinguishes shorts; other platforms only carry
// video vs. livestream, so they fall back to one of those.
export type MediaType = "video" | "livestream" | "short";

// Per-page byte cap for the served stats index. Static hosts limit individual
// file sizes (Cloudflare Pages = 25 MB; smaller elsewhere), so pages are
// flushed by byte size rather than a fixed record count. Kept well under 25 MB.
export const STATS_MAX_PAGE_BYTES = 20 * 1024 * 1024;

export const statsPageFileName = pageFileName;

// One record per video. Engagement fields are nullable: not every platform /
// metadata.info.json carries them, and older archived videos may omit them.
export type VideoStat = {
  slug: string; // `${channelSlug}/${id}`
  id: string;
  channelSlug: string;
  channel: string; // display name
  title: string;
  platform: Platform;
  uploadDate: string; // YYYYMMDD — when the creator published
  // Acquisition dates (YYYYMMDD, UTC) — when *we* added the content. Null when no
  // source is resolvable (pre-sidecar video with no usable mtime). Used by the
  // "content added over time" progress charts; the time X-axis can bin on any of
  // these date fields.
  downloadedDate: string | null;
  // Non-null whenever `hasTranscript` is, since schema 6 (a caption video takes
  // its captions' arrival). A page written by an older build can still carry a
  // transcript with a null date: readers count it and only leave it off a time
  // axis (homepageSummary does exactly that).
  transcribedDate: string | null;
  timestamp: number | null; // unix seconds
  duration: number; // seconds
  viewCount: number | null;
  likeCount: number | null;
  commentCount: number | null;
  channelFollowerCount: number | null;
  categories: string[];
  tags: string[];
  language: string | null;
  isLivestream: boolean;
  mediaType: MediaType;
  status: VideoStatus;
  hasTranscript: boolean;
  cueCount: number | null;
  // Fraction of the video's duration covered by the transcript (last cue end ÷
  // duration). null when there's no transcript or no usable duration. Values
  // well below 1 flag a truncated download (see lib/transcriptCoverage).
  coverage: number | null;
};

export type StatsChannelEntry = {
  slug: string;
  name: string;
  count: number;
};

export type StatsManifest = {
  version: number;
  generatedAt: string;
  totalCount: number;
  pageCount: number;
  // Records the byte cap pages were written under, so a changed cap invalidates
  // stale pages (mirrors the transcript index's ChannelTranscriptsManifest).
  maxPageBytes: number;
  channels: StatsChannelEntry[];
};