import type { FastifyInstance } from 'fastify';
import { z } from 'zod';
import type { Sql } from '../db.js';

export async function getSetting<T = unknown>(
  sql: Sql,
  key: string
): Promise<T | null> {
  const rows = await sql<{ value: T }[]>`SELECT value FROM settings WHERE key = ${key}`;
  return rows[0]?.value ?? null;
}

export async function setSetting(
  sql: Sql,
  key: string,
  value: unknown
): Promise<void> {
  await sql`
    INSERT INTO settings (key, value)
    VALUES (${key}, ${sql.json(value as never)})
    ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value
  `;
}

// themes-v1: whitelist of the 18 preset theme ids. Kept in sync with
// docs/themes_v1.md §1 and apps/web/src/lib/theme.ts THEMES.
const THEME_IDS = [
  'obsidian',
  'gunmetal',
  'espresso',
  'volcanic-brown',
  'copper',
  'gold',
  'oxblood',
  'crimson',
  'elderflower',
  'plum',
  'steel-pink',
  'fuchsia-noir',
  'matrix',
  'sage',
  'ivory',
  'chalk',
  'cobalt',
  'midnight-sapphire',
] as const;

const THEME_MODES = ['dark', 'light', 'system'] as const;

// PATCH body is still a free-form key/value bag for everything except the
// two theme keys, which carry strict per-key validation. Anything outside
// THEME_IDS / THEME_MODES on those keys is rejected with 400.
function validateThemeKeys(body: Record<string, unknown>): string | null {
  if ('theme_id' in body) {
    const v = body.theme_id;
    if (typeof v !== 'string' || !(THEME_IDS as readonly string[]).includes(v)) {
      return `theme_id must be one of: ${THEME_IDS.join(', ')}`;
    }
  }
  if ('theme_mode' in body) {
    const v = body.theme_mode;
    if (typeof v !== 'string' || !(THEME_MODES as readonly string[]).includes(v)) {
      return `theme_mode must be one of: ${THEME_MODES.join(', ')}`;
    }
  }
  return null;
}

const PatchBody = z.record(z.string(), z.unknown());

export function registerSettingsRoutes(app: FastifyInstance, sql: Sql): void {
  app.get('/api/settings', async () => {
    const rows = await sql<{ key: string; value: unknown }[]>`SELECT key, value FROM settings`;
    const out: Record<string, unknown> = {};
    for (const r of rows) out[r.key] = r.value;
    return out;
  });

  app.patch('/api/settings', async (req, reply) => {
    const parsed = PatchBody.safeParse(req.body);
    if (!parsed.success) {
      reply.code(400);
      return { error: 'invalid body', details: parsed.error.flatten() };
    }
    const themeError = validateThemeKeys(parsed.data);
    if (themeError) {
      reply.code(400);
      return { error: themeError };
    }
    for (const [k, v] of Object.entries(parsed.data)) {
      await setSetting(sql, k, v);
    }
    const rows = await sql<{ key: string; value: unknown }[]>`SELECT key, value FROM settings`;
    const out: Record<string, unknown> = {};
    for (const r of rows) out[r.key] = r.value;
    return out;
  });
}