import fs from 'node:fs';
import path from 'node:path';
import { DEFAULT_PROMPT_TEMPLATE } from './bugs.js';

const DEFAULT_STATE = () => ({
  persons: [],
  absences: [],
  holidays: [],
  assignments: {},
  requests: [],
  bugs: [],
  exported: {},
  settings: {
    meetingTime: '09:30',
    durationMinutes: 15,
    bundesland: 'BY',
    calendarDisplayName: 'Morning Meeting',
    inviteAttendees: false,
    historyWindowDays: 60,
    holidaysSeeded: false,
    bugPromptTemplate: DEFAULT_PROMPT_TEMPLATE,
    targetCalendarHref: '',
    targetCalendarName: '',
    absenceCalendarHref: '',
    absenceCalendarName: '',
  },
});

/** Bildtyp anhand der ersten Bytes erkennen. */
export function imageMime(buffer) {
  if (!buffer || buffer.length < 12) return null;
  if (buffer[0] === 0xff && buffer[1] === 0xd8) return 'image/jpeg';
  if (buffer[0] === 0x89 && buffer[1] === 0x50 && buffer[2] === 0x4e && buffer[3] === 0x47) return 'image/png';
  if (buffer.subarray(0, 4).toString('ascii') === 'RIFF' && buffer.subarray(8, 12).toString('ascii') === 'WEBP') return 'image/webp';
  if (buffer.subarray(0, 4).toString('ascii') === 'GIF8') return 'image/gif';
  return null;
}

/** Einfacher JSON-Speicher mit atomarem Schreiben. Fotos liegen daneben im Ordner photos/. */
export function createStore(dataDir) {
  const file = path.join(dataDir, 'rotatory.json');
  const photoDir = path.join(dataDir, 'photos');
  const bugDir = path.join(dataDir, 'bugs');
  fs.mkdirSync(photoDir, { recursive: true });
  fs.mkdirSync(bugDir, { recursive: true });

  let state = DEFAULT_STATE();
  if (fs.existsSync(file)) {
    const loaded = JSON.parse(fs.readFileSync(file, 'utf8'));
    state = { ...state, ...loaded, settings: { ...state.settings, ...(loaded.settings || {}) } };
  }

  function save() {
    const tmp = file + '.tmp';
    fs.writeFileSync(tmp, JSON.stringify(state, null, 2));
    fs.renameSync(tmp, file);
  }

  const photoPath = (id) => path.join(photoDir, `${id}.jpg`);
  return {
    get state() { return state; },
    save,
    photoPath,
    hasPhoto: (id) => fs.existsSync(photoPath(id)),
    readPhoto: (id) => (fs.existsSync(photoPath(id)) ? fs.readFileSync(photoPath(id)) : null),
    savePhoto: (id, buffer) => fs.writeFileSync(photoPath(id), buffer),
    deletePhoto: (id) => { try { fs.unlinkSync(photoPath(id)); } catch {} },
    saveBug: (id, buffer) => fs.writeFileSync(path.join(bugDir, `${id}.png`), buffer),
    readBug: (id) => (fs.existsSync(path.join(bugDir, `${id}.png`)) ? fs.readFileSync(path.join(bugDir, `${id}.png`)) : null),
    deleteBug: (id) => { try { fs.unlinkSync(path.join(bugDir, `${id}.png`)); } catch {} },
  };
}