import { randomUUID } from "node:crypto";
import { db } from "./db.js";

const MAX_NAME_LENGTH = 128;
const NAME_RE = /^[A-Za-z0-9._-]+$/;
const ALLOWED_MIME = new Set(["html", "json"]);

function nowIso() {
  return new Date().toISOString();
}

/**
 * @param {unknown} name
 * @returns {string}
 */
export function assertPageName(name) {
  if (typeof name !== "string" || !NAME_RE.test(name)) {
    const err = new Error("invalid page name");
    err.statusCode = 400;
    throw err;
  }
  if (name.length > MAX_NAME_LENGTH) {
    const err = new Error(`page name must be at most ${MAX_NAME_LENGTH} characters`);
    err.statusCode = 400;
    throw err;
  }
  return name;
}

/**
 * @param {unknown} mime
 * @returns {"html" | "json"}
 */
export function assertMime(mime) {
  const m = String(mime ?? "");
  if (!ALLOWED_MIME.has(m)) {
    const err = new Error('mime must be "html" or "json"');
    err.statusCode = 400;
    throw err;
  }
  return /** @type {"html" | "json"} */ (m);
}

/**
 * @param {unknown} status
 * @returns {number}
 */
export function assertHttpStatus(status, fallback = 200) {
  if (status == null || status === "") return fallback;
  const n = Number(status);
  if (!Number.isInteger(n) || n < 100 || n > 599) {
    const err = new Error("status must be an HTTP status code (100-599)");
    err.statusCode = 400;
    throw err;
  }
  return n;
}

function publicPage(row) {
  return {
    id: row.id,
    name: row.name,
    content: row.content,
    mime: row.mime,
    status: row.status,
    created_at: row.created_at,
    updated_at: row.updated_at,
  };
}

export async function listHttpPages() {
  const rows = await db("http_pages")
    .select("*")
    .orderBy("name", "asc");
  return rows.map(publicPage);
}

/**
 * @param {string} name
 */
export async function getHttpPageByName(name) {
  const row = await db("http_pages").where({ name: assertPageName(name) }).first();
  return row ? publicPage(row) : null;
}

/**
 * @param {string} id
 */
export async function getHttpPageById(id) {
  const row = await db("http_pages").where({ id }).first();
  return row ? publicPage(row) : null;
}

/**
 * @param {{ name: string, content: string, mime: string, status?: number }} opts
 */
export async function upsertHttpPage({ name, content, mime, status }) {
  const pageName = assertPageName(name);
  const pageMime = assertMime(mime);
  const pageStatus = assertHttpStatus(status, 200);
  if (typeof content !== "string") {
    const err = new Error("content must be a string");
    err.statusCode = 400;
    throw err;
  }
  const now = nowIso();
  const existing = await db("http_pages").where({ name: pageName }).first();

  if (existing) {
    await db("http_pages")
      .where({ id: existing.id })
      .update({
        content,
        mime: pageMime,
        status: pageStatus,
        updated_at: now,
      });
    return getHttpPageById(existing.id);
  }

  const id = randomUUID();
  await db("http_pages").insert({
    id,
    name: pageName,
    content,
    mime: pageMime,
    status: pageStatus,
    created_at: now,
    updated_at: now,
  });
  return getHttpPageById(id);
}

/**
 * @param {string} id
 * @returns {Promise<boolean>}
 */
export async function deleteHttpPage(id) {
  const n = await db("http_pages").where({ id }).del();
  return n > 0;
}

/**
 * Content-Type for a page mime.
 * @param {"html" | "json" | string} mime
 */
export function contentTypeForMime(mime) {
  if (mime === "html") return "text/html; charset=utf-8";
  return "application/json; charset=utf-8";
}