const fs = require('fs');
const path = require('path');

const DATA_DIR = path.join(__dirname, 'data');
const UPLOADS_DIR = path.join(__dirname, 'uploads', 'issues');
const ISSUES_FILE = path.join(DATA_DIR, 'issues.json');

function ensureDirs() {
  if (!fs.existsSync(DATA_DIR)) {
    fs.mkdirSync(DATA_DIR, { recursive: true });
  }
  if (!fs.existsSync(UPLOADS_DIR)) {
    fs.mkdirSync(UPLOADS_DIR, { recursive: true });
  }
  if (!fs.existsSync(ISSUES_FILE)) {
    fs.writeFileSync(ISSUES_FILE, JSON.stringify([], null, 2), 'utf-8');
  }
}

function getAllIssues() {
  ensureDirs();
  try {
    const raw = fs.readFileSync(ISSUES_FILE, 'utf-8');
    const list = JSON.parse(raw);
    return Array.isArray(list) ? list : [];
  } catch (err) {
    console.error('Error reading issues.json:', err);
    return [];
  }
}

function saveIssues(issues) {
  ensureDirs();
  const tmpFile = `${ISSUES_FILE}.tmp`;
  fs.writeFileSync(tmpFile, JSON.stringify(issues, null, 2), 'utf-8');
  fs.renameSync(tmpFile, ISSUES_FILE);
}

function generateIssueId() {
  const now = new Date();
  const y = now.getFullYear();
  const m = String(now.getMonth() + 1).padStart(2, '0');
  const d = String(now.getDate()).padStart(2, '0');
  const prefix = `ISS-${y}${m}${d}`;

  const all = getAllIssues();
  const todayCount = all.filter(item => item.id && item.id.startsWith(prefix)).length + 1;
  const seq = String(todayCount).padStart(3, '0');
  return `${prefix}-${seq}`;
}

function createIssue(data, file) {
  ensureDirs();
  const all = getAllIssues();
  const id = generateIssueId();
  const now = new Date().toISOString();

  let attachment = null;
  if (file) {
    attachment = {
      filename: file.filename,
      originalname: file.originalname,
      size: file.size,
      mimetype: file.mimetype,
      url: `/uploads/issues/${file.filename}`,
    };
  }

  const newIssue = {
    id,
    title: (data.title || 'Không có tiêu đề').trim(),
    category: data.category || 'SAI_LECH_SO_LIEU', // SAI_LECH_SO_LIEU, LOI_GIAO_DIEN, LOI_KET_NOI, DE_XUAT, YEU_CAU_MOI, KHAC
    module: data.module || 'CHUNG', // NGOAI_TRU, NOI_TRU, CHUYEN_VIEN, THEO_DOI, CHUNG
    priority: data.priority || 'BINH_THUONG', // THAP, BINH_THUONG, CAO, KHAN_CAP
    database: data.database || '',
    databaseName: data.databaseName || data.database || '',
    period: data.period || '',
    reporter: (data.reporter || 'Cán bộ giao ban').trim(),
    department: (data.department || '').trim(),
    description: (data.description || '').trim(),
    status: 'CHO_XU_LY', // CHO_XU_LY, DANG_XU_LY, DA_XU_LY, DONG
    handlerNotes: '',
    resolvedBy: '',
    resolvedAt: null,
    createdAt: now,
    updatedAt: now,
    attachment,
  };

  all.unshift(newIssue);
  saveIssues(all);
  return newIssue;
}

function updateIssue(id, updates) {
  const all = getAllIssues();
  const idx = all.findIndex(item => item.id === id);
  if (idx === -1) {
    throw new Error(`Không tìm thấy Issue với mã: ${id}`);
  }

  const now = new Date().toISOString();
  const cur = all[idx];

  const updated = {
    ...cur,
    ...updates,
    updatedAt: now,
  };

  if (updates.status === 'DA_XU_LY' && cur.status !== 'DA_XU_LY') {
    updated.resolvedAt = now;
  }

  all[idx] = updated;
  saveIssues(all);
  return updated;
}

function deleteIssue(id) {
  const all = getAllIssues();
  const idx = all.findIndex(item => item.id === id);
  if (idx === -1) {
    throw new Error(`Không tìm thấy Issue với mã: ${id}`);
  }

  const item = all[idx];
  if (item.attachment && item.attachment.filename) {
    const fPath = path.join(UPLOADS_DIR, item.attachment.filename);
    if (fs.existsSync(fPath)) {
      try { fs.unlinkSync(fPath); } catch (e) { /* ignore */ }
    }
  }

  all.splice(idx, 1);
  saveIssues(all);
  return true;
}

module.exports = {
  UPLOADS_DIR,
  ensureDirs,
  getAllIssues,
  createIssue,
  updateIssue,
  deleteIssue,
};