import { test, beforeEach, afterEach } from 'node:test';
import assert from 'node:assert/strict';
import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import request from 'supertest';
import { createApp } from '../src/server/app.js';
import { BOM, readCsv } from './helpers/csv.js';

let tmpDir;
let app;

beforeEach(() => {
  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'tripplan-expense-csv-'));
  app = createApp({ dbPath: path.join(tmpDir, 'test.db'), sessionSecret: 'test-secret' });
});

afterEach(() => {
  try {
    if (app.locals.db) app.locals.db.close();
  } catch {
    /* ignore */
  }
  fs.rmSync(tmpDir, { recursive: true, force: true });
});

// Account with a fixed display_name so CSV columns and payer cells are deterministic.
async function createAccount(displayName) {
  const agent = request.agent(app);
  const created = await agent.post('/api/auth/account').send({});
  assert.equal(created.status, 201);
  const named = await agent.patch('/api/auth/me').send({ display_name: displayName });
  assert.equal(named.status, 200);
  return { agent, user: named.body.user };
}

async function makeTrip(owner, members = [], overrides = {}) {
  const trip = (await owner.agent.post('/api/trips').send({
    name: 'Thailand Trip 2026!', start_date: '2026-08-01', end_date: '2026-08-10',
    currency: 'THB', ...overrides,
  })).body.trip;
  for (const m of members) {
    assert.equal((await m.agent.post('/api/trips/join').send({ code: trip.join_code })).status, 200);
  }
  return trip;
}

async function memberNames(account, trip) {
  const res = await account.agent.get(`/api/trips/${trip.id}`);
  assert.equal(res.status, 200);
  return res.body.members.map((m) => m.display_name);
}

const exportUrl = (trip) => `/api/trips/${trip.id}/expenses/export.csv`;

// ---------------------------------------------------------------------------
// Response headers & encoding
// ---------------------------------------------------------------------------

test('export: content type, filename slug, BOM and CRLF endings', async () => {
  const anna = await createAccount('anna');
  const trip = await makeTrip(anna);
  await anna.agent.post(`/api/trips/${trip.id}/expenses`).send({
    date: '2026-08-02', description: 'Lunch', amount: 100, category: 'food',
  });

  const res = await anna.agent.get(exportUrl(trip));
  assert.equal(res.status, 200);
  assert.equal(res.headers['content-type'], 'text/csv; charset=utf-8');
  assert.equal(
    res.headers['content-disposition'],
    'attachment; filename="thailand-trip-2026-expenses.csv"',
    'slug lowercases, collapses non-alphanumeric runs to "-" and trims them'
  );
  assert.ok(res.text.startsWith(BOM), 'UTF-8 BOM so Excel reads it as UTF-8');
  assert.ok(res.text.includes('\r\n'), 'CRLF line endings');
  // parseCsv fails on any bare LF/CR, so this is the real line-ending assertion.
  const { rows } = readCsv(res.text);
  assert.equal(rows.length, 1);
});

test('export: filename falls back to trip-<id> when the name has no alphanumerics', async () => {
  const anna = await createAccount('anna');
  const trip = await makeTrip(anna, [], { name: '!!! ???' });

  const res = await anna.agent.get(exportUrl(trip));
  assert.equal(res.status, 200);
  assert.equal(res.headers['content-disposition'], `attachment; filename="trip-${trip.id}-expenses.csv"`);
});

test('export: an empty trip yields the header row only', async () => {
  const anna = await createAccount('anna');
  const trip = await makeTrip(anna);

  const { header, rows } = readCsv((await anna.agent.get(exportUrl(trip))).text);
  assert.deepEqual(header, [
    'date', 'source', 'category', 'description', 'amount', 'currency',
    'paid_by', 'split', 'participants', 'share: anna',
  ]);
  assert.deepEqual(rows, [], 'no totals row — data rows only');
});

// ---------------------------------------------------------------------------
// Columns, quoting, interleaving and shares
// ---------------------------------------------------------------------------

test('export: expenses and priced entries interleave by date with correct shares', async () => {
  const anna = await createAccount('anna');
  const ben = await createAccount('ben');
  const trip = await makeTrip(anna, [ben]);
  const entries = `/api/trips/${trip.id}/entries`;
  const expenses = `/api/trips/${trip.id}/expenses`;

  // 08-01 entry, equal, 900 total -> 450 each.
  await anna.agent.post(entries).send({
    date: '2026-08-01', type: 'stay', title: 'Hotel', price: 900, paid_by: anna.user.id,
  });
  // 08-02 expense with a comma AND a double quote in the description.
  await anna.agent.post(expenses).send({
    date: '2026-08-02', description: 'Dinner, "the good" place', amount: 200,
    category: 'food', paid_by: ben.user.id,
  });
  // 08-03 expense, payer split -> ben alone bears it.
  await anna.agent.post(expenses).send({
    date: '2026-08-03', description: 'Solo souvenir', amount: 50, category: 'shopping',
    split_mode: 'payer', paid_by: ben.user.id,
  });
  // 08-04 expense, equal but only ben participates -> ben 60, anna 0.
  await anna.agent.post(expenses).send({
    date: '2026-08-04', description: 'Taxi', amount: 60, category: 'transport',
    paid_by: ben.user.id, participants: [ben.user.id],
  });
  // 08-05 entry, own split at 300/head -> effective total 600, 300 each.
  await anna.agent.post(entries).send({
    date: '2026-08-05', type: 'flight', title: 'Flights', price: 300, split_mode: 'own',
  });
  // Unpriced entry — must not appear at all.
  await anna.agent.post(entries).send({ date: '2026-08-06', type: 'activity', title: 'Free walk' });

  const { header, rows } = readCsv((await anna.agent.get(exportUrl(trip))).text);
  assert.deepEqual(header.slice(-2), ['share: anna', 'share: ben'], 'one share column per member, in display order');
  assert.deepEqual(await memberNames(anna, trip), ['anna', 'ben']);

  assert.deepEqual(
    rows.map((r) => [r.date, r.source, r.description]),
    [
      ['2026-08-01', 'entry', 'Hotel'],
      ['2026-08-02', 'expense', 'Dinner, "the good" place'],
      ['2026-08-03', 'expense', 'Solo souvenir'],
      ['2026-08-04', 'expense', 'Taxi'],
      ['2026-08-05', 'entry', 'Flights'],
    ],
    'chronological, sources interleaved, unpriced entry excluded'
  );

  const [hotel, dinner, souvenir, taxi, flights] = rows;

  assert.deepEqual(hotel, {
    date: '2026-08-01', source: 'entry', category: 'stay', description: 'Hotel',
    amount: '900.00', currency: 'THB', paid_by: 'anna', split: 'equal',
    participants: 'all', 'share: anna': '450.00', 'share: ben': '450.00',
  });

  assert.equal(dinner.category, 'food');
  assert.equal(dinner.amount, '200.00');
  assert.equal(dinner.paid_by, 'ben');
  assert.equal(dinner.participants, 'all');
  assert.deepEqual([dinner['share: anna'], dinner['share: ben']], ['100.00', '100.00']);

  assert.equal(souvenir.split, 'payer');
  assert.equal(souvenir.amount, '50.00');
  assert.deepEqual([souvenir['share: anna'], souvenir['share: ben']], ['0.00', '50.00']);

  assert.equal(taxi.participants, 'ben', 'explicit subset lists display names');
  assert.deepEqual([taxi['share: anna'], taxi['share: ben']], ['0.00', '60.00'],
    'non-participants get 0.00, not an empty cell');

  assert.equal(flights.category, 'flight', 'entry rows carry the entry type as category');
  assert.equal(flights.amount, '600.00', "'own' amount is the effective total (300 x 2)");
  assert.equal(flights.paid_by, '', 'unassigned payer is an empty cell');
  assert.deepEqual([flights['share: anna'], flights['share: ben']], ['300.00', '300.00']);
});

test('export: participants column joins several display names with semicolons', async () => {
  const anna = await createAccount('anna');
  const ben = await createAccount('ben');
  const carol = await createAccount('carol');
  const trip = await makeTrip(anna, [ben, carol]);

  await anna.agent.post(`/api/trips/${trip.id}/expenses`).send({
    date: '2026-08-02', description: 'Shared tuk-tuk', amount: 90, category: 'transport',
    paid_by: anna.user.id, participants: [carol.user.id, anna.user.id],
  });

  const { rows } = readCsv((await anna.agent.get(exportUrl(trip))).text);
  assert.equal(rows[0].participants, 'anna;carol');
  assert.deepEqual(
    [rows[0]['share: anna'], rows[0]['share: ben'], rows[0]['share: carol']],
    ['45.00', '0.00', '45.00']
  );
});

test('export: formula-injection guard on text columns, numbers left alone', async () => {
  const anna = await createAccount('anna');
  const evil = await createAccount('=evil-payer');
  const trip = await makeTrip(anna, [evil]);
  const expenses = `/api/trips/${trip.id}/expenses`;

  const post = (date, description, amount, extra = {}) =>
    anna.agent.post(expenses).send({
      date, description, amount, category: 'food', paid_by: evil.user.id, ...extra,
    });

  await post('2026-08-01', '=HYPERLINK("http://evil")', 380);
  await post('2026-08-02', '-50 refund', 50);
  await post('2026-08-03', '+2 beers', 20);
  await post('2026-08-04', '@lunch spot', 30);
  // Leading `=` AND an embedded comma: must be guarded *and* RFC 4180 quoted.
  await post('2026-08-05', '=SUM(1,2) sneaky', 40, { participants: [evil.user.id] });
  // `=` that is not the first character must be left exactly as typed.
  await post('2026-08-06', 'Total = 5 each', 60);

  const res = await anna.agent.get(exportUrl(trip));
  const { rows } = readCsv(res.text);

  assert.deepEqual(rows.map((r) => r.description), [
    "'=HYPERLINK(\"http://evil\")",
    "'-50 refund",
    "'+2 beers",
    "'@lunch spot",
    "'=SUM(1,2) sneaky",
    'Total = 5 each',
  ]);

  // Numeric columns are server-formatted and must never pick up the prefix.
  assert.deepEqual(rows.map((r) => r.amount), ['380.00', '50.00', '20.00', '30.00', '40.00', '60.00']);
  assert.ok(
    rows.every((r) => !r['share: anna'].startsWith("'") && !r['share: =evil-payer'].startsWith("'")),
    'share columns are numeric and unguarded'
  );

  // Display names reach the spreadsheet through paid_by and participants too.
  assert.ok(rows.every((r) => r.paid_by === "'=evil-payer"), 'payer name is guarded');
  assert.equal(rows[4].participants, "'=evil-payer", 'participant names are guarded');

  // The guard runs before quoting, so the comma row carries both.
  assert.ok(res.text.includes('"\'=SUM(1,2) sneaky"'), 'guard prefix sits inside the quoted field');
});

test('export: non-member gets 404, unauthenticated gets 401', async () => {
  const anna = await createAccount('anna');
  const trip = await makeTrip(anna);
  const outsider = await createAccount('outsider');

  assert.equal((await outsider.agent.get(exportUrl(trip))).status, 404);
  assert.equal((await request(app).get(exportUrl(trip))).status, 401);
});

// ---------------------------------------------------------------------------
// Costs merge
// ---------------------------------------------------------------------------

test('costs: expenses merge with entry costs into one settle-up', async () => {
  const anna = await createAccount('anna');
  const ben = await createAccount('ben');
  const trip = await makeTrip(anna, [ben]);
  const entries = `/api/trips/${trip.id}/entries`;
  const expenses = `/api/trips/${trip.id}/expenses`;

  // Entry: 900 equal, anna paid.
  await anna.agent.post(entries).send({
    date: '2026-08-01', type: 'stay', title: 'Hotel', price: 900, paid_by: anna.user.id,
  });
  // Expense: 200 equal, ben paid.
  await anna.agent.post(expenses).send({
    date: '2026-08-02', description: 'Dinner', amount: 200, category: 'food', paid_by: ben.user.id,
  });
  // Expense: 40 own -> effective 80, each pays their own, no debt.
  await anna.agent.post(expenses).send({
    date: '2026-08-02', description: 'Bus', amount: 40, category: 'transport', split_mode: 'own',
  });
  // Expense: 300 equal with no payer -> unassigned.
  await anna.agent.post(expenses).send({
    date: '2026-08-03', description: 'Cooking class', amount: 300, category: 'activities',
  });

  const c = (await anna.agent.get(`/api/trips/${trip.id}/costs`)).body;
  assert.equal(c.currency, 'THB');
  assert.equal(c.totalCost, 1480, '900 entry + 200 + 80 + 300 expenses');
  assert.deepEqual(c.byType, { stay: 900, expense: 580 }, 'all expenses land in one `expense` bucket');
  assert.equal(c.unassigned, 300);

  const a = c.perUser.find((u) => u.userId === anna.user.id);
  const b = c.perUser.find((u) => u.userId === ben.user.id);
  assert.deepEqual([a.share, a.paid, a.net], [740, 940, 200]);
  assert.deepEqual([b.share, b.paid, b.net], [740, 240, -500]);

  assert.deepEqual(c.settlements, [{ fromUserId: ben.user.id, toUserId: anna.user.id, amount: 200 }]);
});

test('costs: a trip with only expenses still settles up', async () => {
  const anna = await createAccount('anna');
  const ben = await createAccount('ben');
  const trip = await makeTrip(anna, [ben]);

  await anna.agent.post(`/api/trips/${trip.id}/expenses`).send({
    date: '2026-08-02', description: 'Museum tickets', amount: 500, category: 'activities',
    paid_by: anna.user.id,
  });

  const c = (await ben.agent.get(`/api/trips/${trip.id}/costs`)).body;
  assert.equal(c.totalCost, 500);
  assert.deepEqual(c.byType, { expense: 500 });
  assert.equal(c.unassigned, 0);
  assert.deepEqual(c.settlements, [{ fromUserId: ben.user.id, toUserId: anna.user.id, amount: 250 }]);
});

test('costs: deleting an expense removes it from the settle-up again', async () => {
  const anna = await createAccount('anna');
  const ben = await createAccount('ben');
  const trip = await makeTrip(anna, [ben]);

  const e = (await anna.agent.post(`/api/trips/${trip.id}/expenses`).send({
    date: '2026-08-02', description: 'Museum tickets', amount: 500, category: 'activities',
    paid_by: anna.user.id,
  })).body.expense;

  assert.equal((await anna.agent.delete(`/api/expenses/${e.id}`)).status, 204);

  const c = (await anna.agent.get(`/api/trips/${trip.id}/costs`)).body;
  assert.equal(c.totalCost, 0);
  assert.deepEqual(c.byType, {});
  assert.deepEqual(c.settlements, []);
});