const express = require('express');
const router = express.Router();
const fs = require('fs');
const path = require('path');
const { v4: uuidv4 } = require('uuid');

function modifMd(id, modifications) {
  if (id === undefined) throw new Error('id obligatoire');
  if (!Array.isArray(modifications) || modifications.length === 0) throw new Error('modifications requises');

  const dataDir = path.resolve(__dirname, '../data');
  const mapPath = path.join(dataDir, 'uuid_map.json');
  if (!fs.existsSync(mapPath)) throw new Error('uuid_map.json inexistant');

  const map = JSON.parse(fs.readFileSync(mapPath, 'utf8'));
  const uuid = map[id];
  if (!uuid) throw new Error(`Aucun fichier pour l'id ${id}`);

  const mdPath = path.join(dataDir, `${uuid}.md`);
  if (!fs.existsSync(mdPath)) throw new Error('Fichier markdown inexistant');
  let lignes = fs.readFileSync(mdPath, 'utf8').split('\n');

  modifications = modifications.slice().sort((a, b) => a.debut - b.debut);

  let offset = 0;
  for (let m of modifications) {
    let debut = m.debut + offset;
    let fin = m.fin + offset;
    const remplacement = Array.isArray(m.contenu) ? m.contenu : m.contenu.split('\n');
    if (debut < 0 || fin >= lignes.length || debut > fin)
      throw new Error('Plage invalide (début/fin) pour une modification');

    const avant = lignes.slice(0, debut);
    const apres = lignes.slice(fin + 1);
    lignes = [...avant, ...remplacement, ...apres];
    offset += remplacement.length - (fin - debut + 1);
  }

  const nouveau = lignes.join('\n');
  fs.writeFileSync(mdPath, nouveau, { encoding: 'utf8', flag: 'w' });
  return { id, uuid, path: mdPath, modifications };
}


function createMd(markdownContent = "# Titre\nContenu...") {
  const uuid = uuidv4();

  const dataDir = path.resolve(__dirname, '../data');
  const mdPath = path.join(dataDir, `${uuid}.md`);
  const mapPath = path.join(dataDir, 'uuid_map.json');

  fs.writeFileSync(mdPath, markdownContent, { encoding: 'utf8', flag: 'w' });

  let map = {};
  if (fs.existsSync(mapPath)) {
    map = JSON.parse(fs.readFileSync(mapPath, 'utf8'));
  }
  let id = Object.keys(map).at(-1);
  if (id == undefined){
    map[0] = uuid;
  } else {
    id = +id+1
    map[id] = uuid;
  }

  fs.writeFileSync(mapPath, JSON.stringify(map, null, 2), 'utf8');

  return { id, uuid, path: mdPath, markdownContent};
}

function readMd(id = undefined) {
  const dataDir = path.resolve(__dirname, '../data');
  const mapPath = path.join(dataDir, 'uuid_map.json');

  let map = {};
  if (fs.existsSync(mapPath)) {
    map = JSON.parse(fs.readFileSync(mapPath, 'utf8'));
  }

  if (id !== undefined) {
    const uuid = map[id];
    if (!uuid) {
      throw new Error(`Aucun fichier trouvé pour l'id ${id}`);
    }
    const mdPath = path.join(dataDir, `${uuid}.md`);
    if (!fs.existsSync(mdPath)) {
      throw new Error(`Le fichier ${mdPath} n’existe pas`);
    }
    const markdownContent = fs.readFileSync(mdPath, 'utf8');
    return [{ id, uuid, path: mdPath, markdownContent }];
  } else {
    const results = [];
    for (const [curId, uuid] of Object.entries(map)) {
      const mdPath = path.join(dataDir, `${uuid}.md`);
      if (fs.existsSync(mdPath)) {
        const markdownContent = fs.readFileSync(mdPath, 'utf8');
        results.push({ id: curId, uuid, path: mdPath, markdownContent });
      }
    }
    return results;
  }
}

function modifMd(id, newMarkdownContent) {
  if (id === undefined) throw new Error('id obligatoire');
  const dataDir = path.resolve(__dirname, '../data');
  const mapPath = path.join(dataDir, 'uuid_map.json');

  if (!fs.existsSync(mapPath)) throw new Error('uuid_map.json inexistant');
  let map = JSON.parse(fs.readFileSync(mapPath, 'utf8'));
  const uuid = map[id];
  if (!uuid) throw new Error(`Aucun fichier trouvé pour l'id ${id}`);

  const mdPath = path.join(dataDir, `${uuid}.md`);
  if (!fs.existsSync(mdPath)) throw new Error('Le fichier markdown n’existe pas');
  fs.writeFileSync(mdPath, newMarkdownContent, { encoding: 'utf8', flag: 'w' });
  return { id, uuid, path: mdPath, newMarkdownContent };
}

function deteMd(id) {
  if (id === undefined) throw new Error('id obligatoire');
  const dataDir = path.resolve(__dirname, '../data');
  const mapPath = path.join(dataDir, 'uuid_map.json');

  if (!fs.existsSync(mapPath)) throw new Error('uuid_map.json inexistant');
  let map = JSON.parse(fs.readFileSync(mapPath, 'utf8'));
  const uuid = map[id];
  if (!uuid) throw new Error(`Aucun fichier trouvé pour l'id ${id}`);

  const mdPath = path.join(dataDir, `${uuid}.md`);
  if (fs.existsSync(mdPath)) fs.unlinkSync(mdPath);
  delete map[id];

  fs.writeFileSync(mapPath, JSON.stringify(map, null, 2), 'utf8');
  return { id, deleted: true };
}

// GET /api/journals - Récupérer tous les journaux
router.get('/journals', (req, res) => {
  res.json({
    success: true,
    data: readMd()
  });
});

// POST /api/journals - Créer un nouveau journal
router.post('/journals', (req, res) => {
  const { content } = req.body;

  res.status(201).json({
    success: true,
    data: createMd(content)
  });
});

// GET /api/journals/:id - Récupérer un journal spécifique
router.get('/journals/:id', (req, res) => {
  const { id } = req.params;

  res.json({
    success: true,
    data: readMd(id)
  });
});

// PUT /api/journals/:id - Mettre à jour un journal
router.put('/journals/:id', (req, res) => {
  const { id } = req.params;
  const { start, end, content } = req.body;

  res.json({
    success: true,
    data: modifMd(id, {start, end, content})
  });
});

// DELETE /api/journals/:id - Supprimer un journal
router.delete('/journals/:id', (req, res) => {
  const { id } = req.params;

  res.json({
    success: true,
    data: deteMd(id)
  });
});

module.exports = router;