import { createHash } from "node:crypto";
import { mkdirSync, rmSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import type { Context, Hono } from "hono";
import { isSafePath } from "../bucket/repo.ts";
import { applyHidden, openMirror } from "../mirror/store.ts";
import { supportText } from "../pages/docs.ts";
import { html } from "../pages/html.ts";
import { hiddenPaths, ignoredNames, setting } from "../server/db.ts";
import { type AdminContext, adminPage, formField, notice, textFields } from "./console.ts";
import { allRepos, saveSettings } from "./store.ts";

// The settings Phase 6's pages read, with their labels and length caps.
const FIELDS: [key: string, label: string, max: number][] = [
	["site_name", "site name", 100],
	["tagline", "tagline", 300],
	["branding", "branding text", 100],
	["handle", "handle", 39],
	["bio", "bio", 2000],
	["location", "location", 100],
	["link", "link", 500],
	["building_since", "building since", 100],
	["support_page", "support page (Markdown)", 4000],
];
const TEXTAREAS = new Set(["bio", "support_page"]);
const PROFILE_FIELDS = new Set(["handle", "bio", "location", "link", "building_since"]);
const HANDLE = /^[A-Za-z0-9._-]+$/;
const HTTP_URL = /^https?:\/\/[^\s]+$/i;
// Under the 64 KiB body cap with room for the form's other fields; the docs promise 60 KB.
const MAX_SIGNATURE = 60 * 1024;
const OWN_SIGNATURE = /^signature-[0-9a-f]{16}\.(png|jpg|webp)$/;
const MAX_IGNORED = 50;
const MAX_IGNORED_NAME = 255;

/**
 * The signature's type, from its first bytes, never its name or declared type. PNG, JPEG and WebP
 * only: SVG is refused, since it can carry script and links and would need a sandbox of its own.
 */
function imageType(bytes: Uint8Array): "png" | "jpg" | "webp" | null {
	const starts = (sig: number[], at = 0) => sig.every((byte, i) => bytes[at + i] === byte);
	if (starts([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a])) return "png";
	if (starts([0xff, 0xd8, 0xff])) return "jpg";
	if (starts([0x52, 0x49, 0x46, 0x46]) && starts([0x57, 0x45, 0x42, 0x50], 8)) return "webp";
	return null;
}

/** §24's Site and profile section, with the signature image stored under `data/assets/` (§19). */
export function registerSite(app: Hono, ctx: AdminContext): void {
	const assets = join(ctx.dataDir, "assets");
	app.get("/admin/site", (c) => c.html(sitePage(c, ctx, "")));

	app.post("/admin/site", async (c) => {
		const fields = await textFields(c);
		const section = fields.section;
		if (section && section !== "profile" && section !== "site")
			return c.text("Unknown section.", 400);
		const refuse = (error: string) => c.html(sitePage(c, ctx, error, fields), 400);
		const values: Record<string, string> = {};
		for (const [key, label, max] of FIELDS) {
			if (section && PROFILE_FIELDS.has(key) !== (section === "profile")) continue;
			values[key] = (fields[key] ?? "").trim();
			if (values[key].length > max) return refuse(`The ${label} is over ${max} characters.`);
		}
		if (values.handle && !HANDLE.test(values.handle)) {
			return refuse("A handle is letters, digits, '.', '_' and '-'.");
		}
		// Shown by default: the setting records only that it was switched off.
		if (section !== "profile") values.support_off = fields.support === "1" ? "" : "1";
		const ignored = [
			...new Set(
				(fields.ignored ?? "")
					.split(/\r?\n/)
					.map((name) => name.trim())
					.filter(Boolean),
			),
		];
		if (ignored.length > MAX_IGNORED) return refuse(`Up to ${MAX_IGNORED} ignored names.`);
		const bad = ignored.find(
			(name) => name.length > MAX_IGNORED_NAME || name.includes("/") || !isSafePath(name),
		);
		if (bad !== undefined) return refuse(`"${bad}" is not a file or folder name.`);
		const previousIgnored = ignoredNames(ctx.kepr);
		if (section !== "profile") values.ignored = ignored.join("\n");
		if (values.link && !HTTP_URL.test(values.link)) {
			return refuse("The link must be an http or https address.");
		}
		const upload = (await c.req.parseBody()).signature;
		const previous = setting(ctx.kepr, "signature");
		if (
			section === "site" &&
			((upload instanceof File && upload.size > 0) || fields.remove_signature === "1")
		)
			return refuse("Edit your signature in profile settings.");
		if (upload instanceof File && upload.size > MAX_SIGNATURE) {
			return refuse("The signature must be under 60 KB.");
		}
		if (upload instanceof File && upload.size > 0) {
			const bytes = new Uint8Array(await upload.arrayBuffer());
			const type = imageType(bytes);
			if (!type) return refuse("The signature must be a PNG, JPEG or WebP image.");
			// Named by content, so the hour-long /static cache never serves an old signature.
			const hash = createHash("sha256").update(bytes).digest("hex").slice(0, 16);
			values.signature = `signature-${hash}.${type}`;
			mkdirSync(assets, { recursive: true });
			writeFileSync(join(assets, values.signature), bytes);
		} else if (fields.remove_signature === "1") {
			values.signature = "";
		}
		saveSettings(ctx.kepr, values);
		// Only a file this console wrote is removed, whatever the setting holds.
		if (
			previous &&
			OWN_SIGNATURE.test(previous) &&
			values.signature !== undefined &&
			previous !== values.signature
		) {
			rmSync(join(assets, previous), { force: true });
		}
		if (values.ignored !== undefined && values.ignored !== previousIgnored.join("\n")) {
			for (const { name } of allRepos(ctx.kepr)) {
				applyHidden(openMirror(ctx.mirrorDir, name), hiddenPaths(ctx.kepr, name));
			}
		}
		return c.redirect(`/admin/site?${section === "profile" ? "section=profile&" : ""}saved=1`, 303);
	});
}

function sitePage(
	c: Context,
	ctx: AdminContext,
	error: string,
	fields?: Record<string, string>,
): string {
	const profile = (fields?.section ?? c.req.query("section")) === "profile";
	// The support page's box starts from the words it shows today.
	const value = (key: string) =>
		fields
			? (fields[key] ?? "")
			: key === "support_page"
				? supportText(ctx.kepr)
				: (setting(ctx.kepr, key) ?? "");
	const input = ([key, label, max]: (typeof FIELDS)[number]) =>
		html`<label class="issues-label" for="${key}">${label}</label>
${
	TEXTAREAS.has(key)
		? html`<textarea class="issues-textarea" id="${key}" name="${key}" rows="${key === "bio" ? 4 : 12}"
maxlength="${max}">${value(key)}</textarea>`
		: html`<input class="issues-input" id="${key}" name="${key}" maxlength="${max}"
value="${value(key)}">`
}`;
	const body = html`${notice(error)}
<p class="admin-intro">${profile ? "Your public profile brings your work together. A handle gives it an address beginning with @." : "The name and words visitors see across your site."}</p>
${profile && setting(ctx.kepr, "handle") && html`<p><a href="/@${setting(ctx.kepr, "handle")}">view profile ↗</a></p>`}
<form class="issues-form" method="post" action="/admin/site" enctype="multipart/form-data">
${formField(c)}
<input type="hidden" name="section" value="${profile ? "profile" : "site"}">
${FIELDS.filter(([key]) => PROFILE_FIELDS.has(key) === profile).map(input)}
${
	!profile &&
	html`
<label class="issues-label"><input type="checkbox" name="support" value="1"${
		(fields ? fields.support === "1" : !setting(ctx.kepr, "support_off")) && " checked"
	}>
show the support page</label>
<label class="issues-label" for="ignored">ignored in every repo</label>
<p class="admin-intro">One file or folder name per line, such as .agent or AGENTS.md: hidden at
any depth in every repo, from pages and tarballs. Applied after any sync under way.</p>
<textarea class="issues-textarea mono" id="ignored" name="ignored" rows="4">${
		fields ? (fields.ignored ?? "") : ignoredNames(ctx.kepr).join("\n")
	}</textarea>`
}
<button class="issues-submit" type="submit">save ${profile ? "profile" : "site"}</button>
</form>`;
	return adminPage(c, ctx, profile ? "profile" : "site", body);
}