const fs = require('fs');
const path = require('path');
const db = require('../db/database');

var LOG_DIR = path.join(__dirname, '../../data/logs');
if (!fs.existsSync(LOG_DIR)) {
  fs.mkdirSync(LOG_DIR, { recursive: true });
}

function estimateCost(model, inputTokens, outputTokens) {
  if (!model || !inputTokens) return 0;
  var rates = {
    'google/gemini-2.5-flash': { input: 0.075, output: 0.30 },
    'google/gemini-2.5-pro': { input: 1.25, output: 5.00 },
    'deepseek/deepseek-chat-v3-0324': { input: 0.14, output: 0.28 },
    'deepseek/deepseek-r1': { input: 0.55, output: 2.19 },
    'deepseek/deepseek-r1:free': { input: 0, output: 0 },
    'qwen/qwen3-30b-a3b:free': { input: 0, output: 0 },
    'anthropic/vendor-model-sonnet-4': { input: 3.00, output: 15.00 },
    'anthropic/vendor-model-3-haiku': { input: 0.25, output: 1.25 },
    'openai/gpt-4.1-mini': { input: 0.40, output: 1.60 },
    'meta-llama/llama-3.3-70b-instruct': { input: 0.10, output: 0.16 }
  };
  var rate = rates[model] || { input: 0.50, output: 1.00 };
  return ((inputTokens / 1000000) * rate.input) + (((outputTokens || 0) / 1000000) * rate.output);
}

var logger = {

  audit: function(userId, action, details, req, extra) {
    var e = extra || {};
    db.run(
      'INSERT INTO audit_log (user_id, action, category, details, ip_address, user_agent, model_used, tokens_used, duration_ms, status) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)',
      [
        userId || null, action, e.category || 'general',
        typeof details === 'string' ? details : JSON.stringify(details),
        req ? (req.ip || null) : null,
        req ? (req.headers['user-agent'] || '').substring(0, 255) : null,
        e.model || null, e.tokens || null, e.duration || null, e.status || 'success'
      ]
    ).catch(function(err) { console.error('[Logger] Audit failed:', err.message); });
  },

  apiCall: function(userId, endpoint, data) {
    var d = data || {};
    var cost = estimateCost(d.model, d.tokensInput, d.tokensOutput);
    db.run(
      'INSERT INTO api_log (user_id, endpoint, method, status_code, request_size, response_size, model_used, tokens_input, tokens_output, cost_estimate, duration_ms, ip_address, error) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)',
      [
        userId || null, endpoint, d.method || 'POST', d.statusCode || 200,
        d.requestSize || 0, d.responseSize || 0, d.model || null,
        d.tokensInput || 0, d.tokensOutput || 0, cost, d.duration || 0,
        d.ip || null, d.error || null
      ]
    ).catch(function(err) { console.error('[Logger] API log failed:', err.message); });
  },

  access: function(userId, action, req, success) {
    db.run(
      'INSERT INTO access_log (user_id, action, ip_address, user_agent, success) VALUES (?, ?, ?, ?, ?)',
      [
        userId || null, action,
        req ? (req.ip || null) : null,
        req ? (req.headers['user-agent'] || '').substring(0, 255) : null,
        success ? true : false
      ]
    ).catch(function(err) { console.error('[Logger] Access log failed:', err.message); });
  },

  file: function(level, message, data) {
    try {
      var now = new Date();
      var date = now.toISOString().split('T')[0];
      var logFile = path.join(LOG_DIR, date + '.log');
      var line = '[' + now.toISOString() + '] [' + level.toUpperCase() + '] ' + message;
      if (data) line += ' | ' + (typeof data === 'string' ? data : JSON.stringify(data));
      line += '\n';
      fs.appendFileSync(logFile, line);
      if (level === 'error') console.error(line.trim());
    } catch (e) {}
  },

  info: function(msg, data) { this.file('info', msg, data); },
  warn: function(msg, data) { this.file('warn', msg, data); },
  error: function(msg, data) { this.file('error', msg, data); },

  getAuditLogs: function(userId, limit) {
    return db.all('SELECT * FROM audit_log WHERE user_id = ? ORDER BY timestamp DESC LIMIT ?', [userId, limit || 100]);
  },
  getApiLogs: function(userId, limit) {
    return db.all('SELECT * FROM api_log WHERE user_id = ? ORDER BY timestamp DESC LIMIT ?', [userId, limit || 100]);
  },
  getAccessLogs: function(userId, limit) {
    return db.all('SELECT * FROM access_log WHERE user_id = ? ORDER BY timestamp DESC LIMIT ?', [userId, limit || 100]);
  },
  getUsageSummary: function(userId, days) {
    var since = new Date(Date.now() - (days || 30) * 86400000).toISOString();
    return db.all(
      'SELECT COUNT(*) as total_calls, SUM(tokens_input) as total_input_tokens, SUM(tokens_output) as total_output_tokens, SUM(cost_estimate) as total_estimated_cost, AVG(duration_ms) as avg_duration_ms, model_used, endpoint FROM api_log WHERE user_id = ? AND timestamp > ? GROUP BY model_used, endpoint ORDER BY total_calls DESC',
      [userId, since]
    );
  }
};

console.log('✅ Logger initialized');
module.exports = logger;