import { readFileSync } from "node:fs";
import { join } from "node:path";
import type { Context, Hono } from "hono";
import type { Bucket } from "../bucket/reader.ts";
import { isPlatform, isVersion, type ReleaseFile } from "../bucket/repo.ts";
import { headId, repoStats, saveByPrefix } from "../mirror/queries.ts";
import { notFound, openPublicRepo, type PageContext, type PublicRepo } from "../pages/layout.ts";
import { repoIntro } from "../pages/repo.ts";
import { checksumsTxt, historyJson, metaJson, releaseJson, updateInfoJson } from "./feeds.ts";
import { countDownload, type Release, releaseContentType, visibleReleases } from "./releases.ts";

/**
 * §22.4: Koh 2's `koh update` reads `/api/koh/releases/latest`, built into every Koh 2 binary. The
 * route stays on Koh 2's last release forever, never the repo's newest, so a Koh 2 install is never
 * offered Koh 3.
 */
const FROZEN_KOH2 = { repo: "koh", version: "2.1.16" } as const;

// §22.5: one generic script; each repo gets its own name and address filled in.
const INSTALL_SH = readFileSync(join(import.meta.dir, "install.sh"), "utf8");

const JSON_TYPE = "application/json; charset=UTF-8";
const TEXT_TYPE = "text/plain; charset=UTF-8";
// Kepr 2's error bodies. A private repo answers exactly as an unknown one (§20).
const REPO_NOT_FOUND = '{"error":"repo_not_found","message":"repo not found"}';
const NO_RELEASES = '{"error":"not_found","message":"no releases"}';
const RELEASE_NOT_FOUND = '{"error":"not_found","message":"release not found"}';

type Feed = { repo: PublicRepo; releases: Release[] };

export function registerReleaseRoutes(app: Hono, ctx: PageContext, bucket: Bucket): void {
	const send = (c: Context, status: 200 | 404, body: string, type = JSON_TYPE) =>
		c.body(body, status, { "Content-Type": type });
	const feed = (name: string): Feed | null => {
		const repo = openPublicRepo(ctx, name);
		return repo && { repo, releases: visibleReleases(ctx.kepr, repo.mirror, name) };
	};
	// Counted before the redirect (§22.2); Kepr never streams a release file itself.
	const download = (c: Context, repo: string, version: string, file: ReleaseFile) => {
		countDownload(ctx.kepr, repo, version, file.platform);
		const key = `${repo}/releases/${version}/${file.platform}/${file.name}`;
		c.header("Cache-Control", "no-store");
		return c.redirect(bucket.downloadUrl(key, file.name, releaseContentType(file.name)), 302);
	};
	const downloadAt = (c: Context, name: string, version: string, requested: string) => {
		const f = feed(name);
		if (!f) return send(c, 404, REPO_NOT_FOUND);
		// Kepr 2's download links end in `<repo>-<platform>`, so `curl -O` saves a telling name.
		const platform = requested.startsWith(`${name}-`)
			? requested.slice(name.length + 1)
			: requested;
		const release = f.releases.find((r) => r.version === version);
		const file = isPlatform(platform) && release?.files.find((x) => x.platform === platform);
		return file ? download(c, name, version, file) : send(c, 404, RELEASE_NOT_FOUND);
	};
	// The newest visible release, or the response that says why there is none.
	const newest = (c: Context, name: string): Release | Response => {
		const f = feed(name);
		if (!f) return send(c, 404, REPO_NOT_FOUND);
		return f.releases[0] ?? send(c, 404, NO_RELEASES);
	};

	app.get("/api/koh/releases/latest", (c) =>
		send(c, 404, '{"error":"no_releases","message":"no releases available"}'),
	);
	app.get("/api/koh/releases/:version/:platform", (c) =>
		downloadAt(c, FROZEN_KOH2.repo, c.req.param("version"), c.req.param("platform")),
	);
	for (const [path, cors] of [
		["/api/:repo/releases/latest", true],
		["/:repo/releases/latest.json", false],
	] as const) {
		app.get(path, (c) => {
			// §22.4 puts CORS on the route, so its 404s carry it too (Kepr 2 sent it only on success).
			if (cors) c.header("Access-Control-Allow-Origin", "*");
			const release = newest(c, c.req.param("repo"));
			if (release instanceof Response) return release;
			return send(c, 200, releaseJson(ctx.domain, c.req.param("repo"), release));
		});
	}
	for (const [path, cors] of [
		["/api/:repo/releases/history", true],
		["/:repo/releases/history.json", false],
	] as const) {
		app.get(path, (c) => {
			if (cors) c.header("Access-Control-Allow-Origin", "*");
			const f = feed(c.req.param("repo"));
			if (!f) return send(c, 404, REPO_NOT_FOUND);
			if (f.releases.length === 0) return send(c, 404, NO_RELEASES);
			return send(c, 200, historyJson(f.releases));
		});
	}
	app.get("/:repo/releases/latest", (c) => {
		const repo = openPublicRepo(ctx, c.req.param("repo"));
		if (!repo) return notFound(c, ctx);
		return c.redirect(`/${repo.settings.name}/releases`, 302);
	});
	app.get("/:repo/releases/latest/version.txt", (c) => {
		const release = newest(c, c.req.param("repo"));
		return release instanceof Response ? release : send(c, 200, release.version, TEXT_TYPE);
	});
	app.get("/:repo/releases/:version/checksums.txt", (c) => {
		const name = c.req.param("repo");
		const f = feed(name);
		if (!f) return send(c, 404, REPO_NOT_FOUND);
		const release = f.releases.find((r) => r.version === c.req.param("version"));
		if (!release) return send(c, 404, RELEASE_NOT_FOUND);
		return send(c, 200, checksumsTxt(name, release), TEXT_TYPE);
	});
	// §22.1: the newest file for that platform, from the newest release that has one.
	app.get("/:repo/releases/latest/:platform", (c) => {
		const name = c.req.param("repo");
		const f = feed(name);
		if (!f) return send(c, 404, REPO_NOT_FOUND);
		const platform = c.req.param("platform");
		for (const release of f.releases) {
			const file = release.files.find((x) => x.platform === platform);
			if (file) return download(c, name, release.version, file);
		}
		return send(c, 404, RELEASE_NOT_FOUND);
	});
	app.get("/:repo/releases/:version/:platform", (c) => {
		const version = c.req.param("version");
		if (!isVersion(version)) return send(c, 404, RELEASE_NOT_FOUND);
		return downloadAt(c, c.req.param("repo"), version, c.req.param("platform"));
	});
	// Only for a repo with a release, since the script would have nothing to install.
	app.get("/:repo/install.sh", (c) => {
		const name = c.req.param("repo");
		const release = newest(c, name);
		if (release instanceof Response) return release;
		const script = INSTALL_SH.replaceAll("@REPO@", name).replaceAll(
			"@BASE@",
			`https://${ctx.domain}/${name}`,
		);
		c.header("Cache-Control", "public, max-age=60");
		return send(c, 200, script, TEXT_TYPE);
	});
	app.get("/:repo/update-info", (c) => {
		const name = c.req.param("repo");
		const f = feed(name);
		if (!f) return send(c, 404, REPO_NOT_FOUND);
		// §22.4: head is the newest save on the line, a checkpoint included. Its version is the
		// release built from it, else its ID, as in Kepr 2.
		const id = headId(f.repo.mirror);
		const save = id ? saveByPrefix(f.repo.mirror, id) : null;
		const saveHead = save && {
			id: save.id,
			version: f.releases.find((r) => r.save === save.id)?.version ?? save.id,
			createdAt: save.created_at,
		};
		return send(c, 200, updateInfoJson(ctx.domain, name, saveHead ?? null, f.releases[0]));
	});
	app.get("/:repo/meta", (c) => {
		const f = feed(c.req.param("repo"));
		if (!f) return send(c, 404, REPO_NOT_FOUND);
		const { name, category } = f.repo.settings;
		const stats = repoStats(f.repo.mirror);
		const meta = {
			repo: name,
			saveCount: stats.saves,
			lineCount: stats.lines,
			lastSaveAt: stats.updated ?? 0,
			latestRelease: f.releases[0]?.version ?? null,
			description: repoIntro(f.repo)?.text ?? null,
			language: stats.language || null,
			category: category || null,
		};
		return send(c, 200, metaJson(meta));
	});
}