import { defineConfig } from "blume";
import type { StandardSchema } from "blume/core/standard-schema.ts";
import { hashText } from "blume/core/sources/cache.ts";
import type { ContentSource } from "blume/core/sources/types.ts";
import { custom, filesystem } from "blume/sources";
import { githubReleasesSource } from "blume/sources/github-releases.ts";
import redirects from "./redirects";

/**
 * GitHub releases → /changelog, dated by the real finish instant of the topic
 * or `Review <N> — <Phase>` issue each release records.
 *
 * Blume dates a release entry by `published_at`, which the GitHub API cannot
 * backdate — so the releases backfilled on one day (apps/cli/
 * release-topics.ts) would all read that day. Their tags are timever
 * (`YYYYMMDD.HHMMSS.NNNNNNNNN`, UTC) of the moment the topic or review
 * finished, so this fetch rewrites each timever release's `published_at` to
 * that instant before Blume maps it; anything else passes through untouched.
 * The config-level `githubReleases()` accepts no `fetchImpl`, hence the
 * `custom()` wrap of the underlying source (the `blume/sources/*.ts` path the
 * Blume docs use for custom sources), with the context the built-in adapter
 * would receive.
 */
const TIMEVER = /^(\d{4})(\d{2})(\d{2})\.(\d{2})(\d{2})(\d{2})\.\d{9}$/;

const releasesDatedByTag: typeof fetch = async (input, init) => {
  const res = await fetch(input, init);
  if (!res.ok) return res;
  const releases: unknown = await res.json();
  if (Array.isArray(releases)) {
    for (const release of releases) {
      const m =
        typeof release?.tag_name === "string"
          ? release.tag_name.match(TIMEVER)
          : null;
      if (m)
        release.published_at = `${m[1]}-${m[2]}-${m[3]}T${m[4]}:${m[5]}:${m[6]}Z`;
    }
  }
  // Blume reads only `ok` and the JSON body, so the original headers (whose
  // content-length/encoding describe the upstream bytes) are not carried over.
  return Response.json(releases, { status: res.status });
};

/**
 * The changelog index tags every row with `changelog.category`, which the
 * GitHub source sets to "Release" for all of them. release-topics.ts names
 * each release after its issue, so the title prefix says which kind finished
 * — a topic's core set, or a Review day block — and the row is tagged
 * `Topic` / `Review` instead. The category lives both in `data` and in the
 * staged `raw` frontmatter Astro re-parses, so both are rewritten (and the
 * hash with them). Wrapped around the source Blume rebuilds via
 * `withContext`, so the rebuilt one is tagged too.
 */
const RELEASE_KIND = /^(Topic|Review) \d+ — /;

const releasesByKind = (source: ContentSource): ContentSource => ({
  ...source,
  load: async () => {
    const result = await source.load();
    for (const entry of result.entries) {
      const kind = typeof entry.data.title === "string" ? entry.data.title.match(RELEASE_KIND)?.[1] : undefined;
      const changelog = entry.data.changelog;
      if (!kind || !changelog || typeof changelog !== "object" || !("category" in changelog)) continue;
      changelog.category = kind;
      if (entry.raw) {
        entry.raw = entry.raw.replace(/^( {2}category: ).*$/m, `$1${kind}`);
        entry.hash = hashText(entry.raw);
      }
    }
    return result;
  },
  withContext: source.withContext && ((ctx) => releasesByKind(source.withContext!(ctx))),
});

// Blume's defaults (`inter`, `ibm-plex-mono`) are fetched from fonts.gstatic.com
// on every build, which has timed out on the Pages runner and, fully offline,
// silently ships no fonts at all. The same two families from Fontsource, as
// local files, keep the build network-free. Blume resolves `src` from this
// directory; the workspace links these packages under ./node_modules.
const inter = {
  name: "Inter",
  variants: [
    {
      src: "./node_modules/@fontsource-variable/inter/files/inter-latin-wght-normal.woff2",
      weight: "100..900",
    },
  ],
};
const plexMono = {
  name: "IBM Plex Mono",
  variants: [
    {
      src: "./node_modules/@fontsource/ibm-plex-mono/files/ibm-plex-mono-latin-400-normal.woff2",
      weight: 400,
    },
    {
      src: "./node_modules/@fontsource/ibm-plex-mono/files/ibm-plex-mono-latin-500-normal.woff2",
      weight: 500,
    },
  ],
};

/**
 * Custom frontmatter, rendered as the badge row by
 * components/ProblemBadges.astro. Problem pages: `topics:` is LeetCode's topic
 * tags (written by apps/cli/sync.ts), `video:` the NeetCode walkthrough's
 * YouTube id (apps/cli/videos.ts). Guide pages (content/guides/, created by
 * sync): `list:` is the tag's LeetCode problem list. Blume rejects undeclared
 * keys and takes any Standard Schema; these are hand-rolled so the docs
 * workspace needs no zod. All optional — every other page carries none.
 */
const optional = <T>(
  message: string,
  valid: (value: unknown) => value is T,
): StandardSchema<unknown, T | undefined> => ({
  "~standard": {
    version: 1,
    vendor: "prdlk",
    validate: (value) =>
      value === undefined || valid(value)
        ? { value }
        : { issues: [{ message }] },
  },
});

const topicsSchema = optional(
  "expected a list of { name, slug } LeetCode topic tags",
  (value): value is { name: string; slug: string }[] =>
    Array.isArray(value) &&
    value.every(
      (t) => typeof t?.name === "string" && typeof t?.slug === "string",
    ),
);
const videoSchema = optional(
  "expected an 11-character YouTube video id",
  (value): value is string =>
    typeof value === "string" && /^[\w-]{11}$/.test(value),
);
const listSchema = optional(
  "expected a https://leetcode.com/problem-list/<slug>/ URL",
  (value): value is string =>
    typeof value === "string" &&
    /^https:\/\/leetcode\.com\/problem-list\/[\w-]+\/$/.test(value),
);

export default defineConfig({
  title: "prdlk",
  description: "Documentation for my LeetCode solutions",
  logo: "./public/logo.svg",
  deployment: {
    site: "https://lc.prd.lk",
  },
  github: {
    owner: "prdlk",
    repo: "leetcode",
  },
  lastModified: "git",
  redirects,
  frontmatter: {
    extend: { topics: topicsSchema, video: videoSchema, list: listSchema },
  },
  seo: {
    og: { enabled: true },
    rss: { enabled: true, types: ["changelog"] },
    sitemap: true,
    robots: true,
    structuredData: true,
    x: { handle: "@prdlk" },
  },
  // Blume's own assistant route is server-rendered (it reads the provider key
  // per request), which a static Pages build cannot ship. The SRS Worker
  // answers instead (apps/api/src/ask.ts: OpenRouter, grounded on this site's
  // llms-full.txt, which `agents.llmsTxt` publishes).
  ai: {
    assistant: {
      enabled: true,
      endpoint: "https://srs-api.prdlk.workers.dev/ask",
    },
  },
  agents: {
    llmsTxt: true,
    mcp: { enabled: false },
  },
  content: {
    sources: [
      filesystem({ root: "content" }),
      custom(
        releasesByKind(
          githubReleasesSource(
            {
              name: "changelog",
              prefix: "changelog",
              owner: "prdlk",
              repo: "leetcode",
              fetchImpl: releasesDatedByTag,
            },
            // What resolve.ts hands the built-in adapter: `.blume/cache/<name>/`,
            // and a refresh on every load (the source reads nothing else).
            {
              projectRoot: import.meta.dirname,
              cacheDir: `${import.meta.dirname}/.blume/cache/changelog`,
              mode: "build",
            },
          ),
        ),
      ),
    ],
  },
  theme: {
    fonts: { display: inter, body: inter, mono: plexMono },
  },
  navigation: {
    sidebar: {
      display: "flat", // "flat" | "group" | "page"
    },
    tabs: [
      { label: "Guides", path: "/guides" },
      { label: "Changelog", path: "/changelog" },
    ],
  },
});