import type { FastifyInstance, FastifyReply, FastifyRequest } from 'fastify';
import type { DB } from '../db.js';
import { businessDay, formatLocal, parseDbTime } from '../time.js';

const SESSION_COOKIE = 'wutz_admin';

// Generous ceiling for a single drink price or deposit amount — bounds a
// typo (or a `2.5`/`"abc"` slipping past a missing check) from wrecking a
// bar's pricing. See wutzcalc#12.
const MAX_CENTS = 100_000_00; // 100,000 €
function isValidCents(v: unknown): v is number {
  return typeof v === 'number' && Number.isInteger(v) && v >= 0 && v <= MAX_CENTS;
}

function isAuthed(req: FastifyRequest): boolean {
  const expected = process.env.ADMIN_PASSWORD;
  if (!expected) return false;
  return req.cookies?.[SESSION_COOKIE] === expected;
}

function requireAuth(req: FastifyRequest, reply: FastifyReply): boolean {
  if (isAuthed(req)) return true;
  reply.code(401).send({ error: 'unauthorized' });
  return false;
}

export function registerAdminRoutes(app: FastifyInstance, db: DB) {
  app.post<{ Body: { password?: string } }>('/admin/login', async (req, reply) => {
    const expected = process.env.ADMIN_PASSWORD;
    if (!expected) return reply.code(500).send({ error: 'ADMIN_PASSWORD not set' });
    if (req.body?.password !== expected) return reply.code(401).send({ error: 'wrong password' });
    reply.setCookie(SESSION_COOKIE, expected, {
      path: '/',
      httpOnly: true,
      sameSite: 'lax',
      maxAge: 60 * 60 * 24 * 7,
    });
    return { ok: true };
  });

  app.post('/admin/logout', async (_req, reply) => {
    reply.clearCookie(SESSION_COOKIE, { path: '/' });
    return { ok: true };
  });

  app.get('/admin/api/me', async (req) => ({ authed: isAuthed(req) }));

  // ----- Drinks -----
  app.get('/admin/api/drinks', async (req, reply) => {
    if (!requireAuth(req, reply)) return;
    return db
      .prepare('SELECT id, name, price_cents, archived FROM drinks ORDER BY archived, id')
      .all();
  });

  app.post<{ Body: { name: string; price_cents: number } }>(
    '/admin/api/drinks',
    async (req, reply) => {
      if (!requireAuth(req, reply)) return;
      const { name, price_cents } = req.body ?? ({} as any);
      if (!name || !isValidCents(price_cents)) return reply.code(400).send({ error: 'invalid' });
      const info = db
        .prepare('INSERT INTO drinks (name, price_cents) VALUES (?, ?)')
        .run(name, price_cents);
      return { id: Number(info.lastInsertRowid) };
    }
  );

  app.patch<{ Params: { id: string }; Body: { name?: string; price_cents?: number; archived?: boolean } }>(
    '/admin/api/drinks/:id',
    async (req, reply) => {
      if (!requireAuth(req, reply)) return;
      const id = Number(req.params.id);
      const { name, price_cents, archived } = req.body ?? {};
      if (price_cents !== undefined && !isValidCents(price_cents)) {
        return reply.code(400).send({ error: 'invalid price_cents' });
      }
      const sets: string[] = [];
      const args: any[] = [];
      if (name !== undefined) { sets.push('name = ?'); args.push(name); }
      if (price_cents !== undefined) { sets.push('price_cents = ?'); args.push(price_cents); }
      if (archived !== undefined) { sets.push('archived = ?'); args.push(archived ? 1 : 0); }
      if (sets.length === 0) return { ok: true };
      args.push(id);
      db.prepare(`UPDATE drinks SET ${sets.join(', ')} WHERE id = ?`).run(...args);
      return { ok: true };
    }
  );

  app.delete<{ Params: { id: string } }>('/admin/api/drinks/:id', async (req, reply) => {
    if (!requireAuth(req, reply)) return;
    const id = Number(req.params.id);
    const sold = db
      .prepare('SELECT 1 FROM transaction_items WHERE drink_id = ? LIMIT 1')
      .get(id);
    if (sold) {
      return reply
        .code(409)
        .send({ error: 'Getränk wurde bereits verkauft — bitte archivieren statt löschen.' });
    }
    db.transaction(() => {
      db.prepare('DELETE FROM bar_drinks WHERE drink_id = ?').run(id);
      db.prepare('DELETE FROM drinks WHERE id = ?').run(id);
    })();
    return { ok: true };
  });

  // ----- Bars -----
  app.get('/admin/api/bars', async (req, reply) => {
    if (!requireAuth(req, reply)) return;
    const bars = db.prepare('SELECT id, name, pfand_cents FROM bars ORDER BY id').all() as any[];
    const drinkRows = db
      .prepare('SELECT bar_id, drink_id, sort_order FROM bar_drinks ORDER BY sort_order, drink_id')
      .all() as any[];
    return bars.map(b => ({
      ...b,
      drink_ids: drinkRows.filter(d => d.bar_id === b.id).map(d => d.drink_id),
    }));
  });

  app.post<{ Body: { name: string; pfand_cents?: number } }>(
    '/admin/api/bars',
    async (req, reply) => {
      if (!requireAuth(req, reply)) return;
      const name = req.body?.name?.trim();
      const pfand_cents = req.body?.pfand_cents ?? 0;
      if (!name) return reply.code(400).send({ error: 'name required' });
      if (!isValidCents(pfand_cents)) {
        return reply.code(400).send({ error: 'invalid pfand_cents' });
      }
      try {
        const info = db
          .prepare('INSERT INTO bars (name, pfand_cents) VALUES (?, ?)')
          .run(name, pfand_cents);
        return { id: Number(info.lastInsertRowid) };
      } catch (e: any) {
        if (String(e.message).includes('UNIQUE')) {
          return reply.code(409).send({ error: 'name already exists' });
        }
        throw e;
      }
    }
  );

  app.patch<{ Params: { id: string }; Body: { name?: string; pfand_cents?: number; drink_ids?: number[] } }>(
    '/admin/api/bars/:id',
    async (req, reply) => {
      if (!requireAuth(req, reply)) return;
      const id = Number(req.params.id);
      const { name, pfand_cents, drink_ids } = req.body ?? {};
      if (pfand_cents !== undefined && !isValidCents(pfand_cents)) {
        return reply.code(400).send({ error: 'invalid pfand_cents' });
      }
      try {
        db.transaction(() => {
          if (name !== undefined) {
            const trimmed = name.trim();
            if (!trimmed) throw new Error('name empty');
            db.prepare('UPDATE bars SET name = ? WHERE id = ?').run(trimmed, id);
          }
          if (pfand_cents !== undefined) {
            db.prepare('UPDATE bars SET pfand_cents = ? WHERE id = ?').run(pfand_cents, id);
          }
          if (Array.isArray(drink_ids)) {
            db.prepare('DELETE FROM bar_drinks WHERE bar_id = ?').run(id);
            const ins = db.prepare(
              'INSERT INTO bar_drinks (bar_id, drink_id, sort_order) VALUES (?, ?, ?)'
            );
            drink_ids.forEach((did, idx) => ins.run(id, did, idx));
          }
        })();
      } catch (e: any) {
        if (String(e.message).includes('UNIQUE')) {
          return reply.code(409).send({ error: 'name already exists' });
        }
        if (e.message === 'name empty') return reply.code(400).send({ error: 'name empty' });
        throw e;
      }
      return { ok: true };
    }
  );

  app.delete<{ Params: { id: string } }>('/admin/api/bars/:id', async (req, reply) => {
    if (!requireAuth(req, reply)) return;
    const id = Number(req.params.id);
    const used = db
      .prepare('SELECT 1 FROM transactions WHERE bar_id = ? LIMIT 1')
      .get(id);
    if (used) {
      return reply
        .code(409)
        .send({ error: 'Tresen hat Transaktionen — Löschen würde die Statistik verfälschen.' });
    }
    db.transaction(() => {
      db.prepare('DELETE FROM bar_drinks WHERE bar_id = ?').run(id);
      db.prepare('DELETE FROM bars WHERE id = ?').run(id);
    })();
    return { ok: true };
  });

  // ----- Stats -----
  app.get('/admin/api/stats', async (req, reply) => {
    if (!requireAuth(req, reply)) return;

    // LEFT JOIN (not JOIN) so a bar with zero sales still gets a zero row —
    // an inner join made a brand-new bar indistinguishable from a deleted
    // one until its first sale, which reads as "my new bar isn't working"
    // during setup. COUNT(t.id), not COUNT(*): the outer join produces one
    // NULL-filled row per bar-with-no-transactions, and COUNT(*) would
    // count that as 1 instead of 0.
    const totals = db
      .prepare(
        `SELECT b.id AS bar_id, b.name AS bar_name,
                COUNT(t.id) AS tx_count,
                COALESCE(SUM(CASE WHEN t.crew = 0 THEN t.total_cents ELSE 0 END), 0) AS paid_cents,
                COALESCE(SUM(CASE WHEN t.crew = 1 THEN 1 ELSE 0 END), 0) AS crew_count,
                COALESCE(SUM(t.pfand_returns), 0) AS pfand_returns
           FROM bars b
           LEFT JOIN transactions t ON t.bar_id = b.id
          GROUP BY b.id, b.name
          ORDER BY b.id`
      )
      .all();

    const perDrink = db
      .prepare(
        `SELECT d.id AS drink_id, d.name AS drink_name,
                COALESCE(SUM(ti.qty), 0) AS sold_qty
           FROM transaction_items ti
           JOIN drinks d ON d.id = ti.drink_id
          GROUP BY d.id, d.name
          ORDER BY sold_qty DESC, d.id`
      )
      .all();

    // Per business day (sales night runs past midnight — see time.ts).
    //
    // Deliberately still computed in JS rather than SQL, despite selecting
    // every transaction row on every stats load: businessDay() uses
    // Intl.DateTimeFormat with a named IANA zone (WUTZ_TZ), which handles
    // DST transitions correctly. A SQL `date(created_at, '-Nh', 'localtime')`
    // rewrite would use the *server process's* OS timezone (not WUTZ_TZ) and
    // a fixed hour offset that's wrong on the two nights a year DST changes
    // — a real correctness regression for a money-adjacent report, to fix a
    // performance concern that (per the code review that flagged this) is
    // "fine today" at festival scale. Not worth the trade.
    const txRows = db
      .prepare('SELECT created_at, total_cents, crew, pfand_returns FROM transactions')
      .all() as Array<{ created_at: string; total_cents: number; crew: number; pfand_returns: number }>;

    const dayMap = new Map<string, { day: string; tx_count: number; paid_cents: number; crew_count: number; pfand_returns: number }>();
    for (const r of txRows) {
      const day = businessDay(parseDbTime(r.created_at));
      let agg = dayMap.get(day);
      if (!agg) {
        agg = { day, tx_count: 0, paid_cents: 0, crew_count: 0, pfand_returns: 0 };
        dayMap.set(day, agg);
      }
      agg.tx_count += 1;
      if (r.crew) agg.crew_count += 1;
      else agg.paid_cents += r.total_cents;
      agg.pfand_returns += r.pfand_returns;
    }
    const byDay = [...dayMap.values()].sort((a, b) => b.day.localeCompare(a.day));

    return { totals, per_drink: perDrink, by_day: byDay };
  });

  app.post('/admin/api/stats/reset', async (req, reply) => {
    if (!requireAuth(req, reply)) return;
    db.transaction(() => {
      db.prepare('DELETE FROM transaction_items').run();
      db.prepare('DELETE FROM transactions').run();
    })();
    return { ok: true };
  });

  // ----- CSV export -----
  app.get<{ Querystring: { what?: string } }>('/admin/api/export.csv', async (req, reply) => {
    if (!requireAuth(req, reply)) return;
    const what = req.query.what === 'items' ? 'items' : 'transactions';

    let rows: any[];
    let header: string[];
    if (what === 'transactions') {
      header = ['id', 'bar_id', 'bar_name', 'created_at', 'total_cents', 'crew', 'pfand_returns', 'pfand_cents_at_sale', 'client_ip', 'client_uuid'];
      rows = db
        .prepare(
          `SELECT t.id, t.bar_id, b.name AS bar_name, t.created_at, t.total_cents,
                  t.crew, t.pfand_returns, t.pfand_cents_at_sale, t.client_ip, t.client_uuid
             FROM transactions t JOIN bars b ON b.id = t.bar_id
            ORDER BY t.id`
        )
        .all() as any[];
    } else {
      header = [
        'transaction_id', 'bar_id', 'created_at', 'drink_id', 'drink_name',
        'qty', 'unit_price_cents', 'pfand_cents_per_unit',
      ];
      rows = db
        .prepare(
          `SELECT ti.transaction_id, t.bar_id, t.created_at, ti.drink_id, d.name AS drink_name,
                  ti.qty, ti.unit_price_cents, ti.pfand_cents_per_unit
             FROM transaction_items ti
             JOIN transactions t ON t.id = ti.transaction_id
             JOIN drinks d ON d.id = ti.drink_id
            ORDER BY ti.transaction_id, ti.id`
        )
        .all() as any[];
    }

    // created_at is stored as UTC — export it as local wall-clock time.
    for (const r of rows) {
      if (r.created_at) r.created_at = formatLocal(parseDbTime(r.created_at));
    }

    const csv = [header.join(',')]
      .concat(rows.map(r => header.map(h => csvCell(r[h])).join(',')))
      .join('\n');

    reply
      .header('Content-Type', 'text/csv; charset=utf-8')
      .header('Content-Disposition', `attachment; filename="${what}.csv"`)
      .send(csv);
  });
}

function csvCell(v: unknown): string {
  if (v === null || v === undefined) return '';
  let s = String(v);
  // Neutralise spreadsheet formula injection: a cell starting with one of
  // these characters is interpreted as a formula by Excel/LibreOffice when
  // the CSV is opened (e.g. a drink named =HYPERLINK("http://…")). Admin-
  // entered data only, so low risk, but the fix is one character.
  if (/^[=+\-@]/.test(s)) s = `'${s}`;
  if (/[",\n]/.test(s)) return `"${s.replace(/"/g, '""')}"`;
  return s;
}