import fs from "node:fs";
import { writeJsonAtomic } from "./jsonFile-server";
import { getPaths, type Paths } from "./paths";
import { PROJECT_NAME, PROJECT_TAGLINE } from "./project";
import {
  getSettings,
  parseSocialLinks,
  type SiteSettings,
  type SocialLink,
} from "./settings";
import { socialLinksForSave } from "./socialLinks";

// The Archilyzer hub/homepage is a SINGLE, instance-level landing site (the
// `homepage` SSG package) that sits above the per-content sites. Unlike a Site,
// it has no channel membership and no grouping layout — it's just branding,
// social links, and an optional cross-site chart dashboard (chart-templates.json,
// same shape sites use); the home route renders a cross-site stats landing built
// from the whole channel pool. Config lives at homepageConfigFile
// (sites/_homepage/homepage.json); operational config stays global in
// settings.json.

export type HomepageConfig = {
  siteTitle: string;
  siteDescription: string;
  headerTitle: string;
  homeTagline: string;
  // Per-hub social links. `undefined` = inherit the global default from
  // SiteSettings.socialLinks; an array (even empty) overrides it. Same semantics
  // as Site.socialLinks — resolve with resolveHomepageSocialLinks() at render.
  socialLinks?: SocialLink[];
  // Absolute public URL of the deployed hub, e.g. "https://archilyzer-hub.pages.dev".
  siteUrl?: string;
  // Cloudflare Pages project the hub deploys to (e.g. "archilyzer-hub"; never
  // "archilyzer", the homepage's — the hub's deploy refuses it, hubProjectProblem).
  cloudflareProject?: string;
  // The transcript modal's per-video export controls (Download menu, Copy MD;
  // the yt-dlp clip command shows either way) on the hub's Browse and Ask pages — the same switch
  // as site.json `transcriptDownloads`. Opt-OUT: absent = on; only an explicit
  // false is read, and only false is written.
  transcriptDownloads?: boolean;
};

// Neutral defaults for an unconfigured install. These are the PRODUCT strings
// (common/lib/project.ts) standing in until the operator names their own
// deployment in the editor — which is why they're pulled from the constant
// rather than spelled out here twice.
function defaults(): HomepageConfig {
  return {
    siteTitle: PROJECT_NAME,
    siteDescription: PROJECT_TAGLINE,
    headerTitle: PROJECT_NAME,
    homeTagline: "",
  };
}

// Normalize a raw siteUrl into a trimmed absolute http(s) URL with no trailing
// slash, or undefined. Mirrors parseSiteUrl in site.ts.
export function parseHomepageUrl(input: unknown): string | undefined {
  if (typeof input !== "string") return undefined;
  const trimmed = input.trim().replace(/\/+$/, "");
  if (!/^https?:\/\/\S+/i.test(trimmed)) return undefined;
  return trimmed;
}

export function parseHomepageConfig(raw: unknown): HomepageConfig {
  const base = defaults();
  const r =
    raw && typeof raw === "object" ? (raw as Record<string, unknown>) : {};
  const str = (key: keyof HomepageConfig, fallback: string): string =>
    typeof r[key] === "string" ? (r[key] as string) : fallback;
  return {
    siteTitle: str("siteTitle", base.siteTitle),
    siteDescription: str("siteDescription", base.siteDescription),
    headerTitle: str("headerTitle", base.headerTitle),
    homeTagline: str("homeTagline", base.homeTagline),
    socialLinks: Array.isArray(r.socialLinks)
      ? parseSocialLinks(r.socialLinks)
      : undefined,
    siteUrl: parseHomepageUrl(r.siteUrl),
    cloudflareProject:
      typeof r.cloudflareProject === "string" && r.cloudflareProject.trim()
        ? r.cloudflareProject.trim()
        : undefined,
    transcriptDownloads: r.transcriptDownloads === false ? false : undefined,
  };
}

export function getHomepageConfig(paths: Paths = getPaths()): HomepageConfig {
  let parsed: unknown = {};
  try {
    parsed = JSON.parse(fs.readFileSync(paths.homepageConfigFile, "utf8"));
  } catch {
    parsed = {};
  }
  return parseHomepageConfig(parsed);
}

// The effective social links for the hub: its own override when present, else
// the global default. Mirrors resolveSocialLinks for Sites.
export function resolveHomepageSocialLinks(
  config: HomepageConfig,
  settings: SiteSettings = getSettings(),
): SocialLink[] {
  return config.socialLinks ?? settings.socialLinks;
}

export async function writeHomepageConfig(
  config: HomepageConfig,
  paths: Paths = getPaths(),
): Promise<void> {
  // A link whose SVG is unchanged from homepage.json on disk is kept as it is;
  // a new or edited one is checked (lib/socialLinks.ts socialLinksForSave).
  let socialLinks: SocialLink[] | undefined;
  if (config.socialLinks !== undefined) {
    const r = socialLinksForSave(
      parseSocialLinks(config.socialLinks),
      getHomepageConfig(paths).socialLinks,
    );
    if ("refused" in r) {
      throw new Error(`Social link "${r.refused.label}" has an invalid SVG: ${r.refused.problem}`);
    }
    socialLinks = r.links;
  }
  const merged: HomepageConfig = {
    siteTitle: config.siteTitle,
    siteDescription: config.siteDescription,
    headerTitle: config.headerTitle,
    homeTagline: config.homeTagline,
    ...(socialLinks !== undefined ? { socialLinks } : {}),
    ...(parseHomepageUrl(config.siteUrl)
      ? { siteUrl: parseHomepageUrl(config.siteUrl) }
      : {}),
    ...(config.cloudflareProject && config.cloudflareProject.trim()
      ? { cloudflareProject: config.cloudflareProject.trim() }
      : {}),
    ...(config.transcriptDownloads === false ? { transcriptDownloads: false } : {}),
  };
  // mkdir: the parent of homepageConfigFile IS homepageDir (lib/paths.ts).
  await writeJsonAtomic(paths.homepageConfigFile, merged, { mkdir: true });
}