import fs from 'fs';
import path from 'path';

const DATA_DIR = path.resolve(process.cwd(), 'public/data');

if (!fs.existsSync(DATA_DIR)) {
  console.error("Data directory not found.");
  process.exit(1);
}

const files = fs.readdirSync(DATA_DIR).filter(f => f.endsWith('.json') && f !== 'lakes_index.json');

files.forEach(file => {
  const filePath = path.join(DATA_DIR, file);
  const data = JSON.parse(fs.readFileSync(filePath, 'utf-8'));
  if (data.length === 0) return;

  // The oldest record currently in DB
  const oldest = data[0];
  const oldestTime = new Date(oldest.timestamp).getTime();
  
  const newRecords: any[] = [];
  
  let currentLevel = oldest.level;
  let currentFlow = oldest.flow;
  let currentInflow = oldest.inflow || (Math.random() * 10 + 5);
  
  // Generate 720 records (30 days * 24 hours) going BACKWARDS
  for (let i = 1; i <= 720; i++) {
    const d = new Date(oldestTime - i * 60 * 60 * 1000);
    
    // random walk for level
    currentLevel = currentLevel + (Math.random() - 0.5) * 0.05;
    
    // random walk for outflow and inflow
    currentFlow = Math.max(0, currentFlow + (Math.random() - 0.5) * 2);
    currentInflow = Math.max(0, currentInflow + (Math.random() - 0.5) * 2);
    
    // Temperature: daily sine wave (colder at night, warmer in day) + noise
    const hour = d.getHours();
    const tempBase = 18; // base 18C
    const tempDay = Math.sin(((hour - 6) / 24) * Math.PI * 2) * 8; // cold morning, warm afternoon
    const randomTemp = tempBase + tempDay + (Math.random() - 0.5) * 2;
    
    // Precipitation: rare spikes
    const randomPrecip = Math.random() > 0.95 ? Math.random() * 15 : 0;
    
    newRecords.push({
      timestamp: d.toISOString(),
      level: currentLevel,
      flow: currentFlow,
      inflow: currentInflow,
      volume: oldest.volume, // volume changes too slow, keep constant for mock
      temperature: randomTemp,
      precipitation: randomPrecip
    });
  }
  
  // Combine: newRecords are older, so reverse them to make chronological (oldest first), then add real data
  const allRecords = [...newRecords.reverse(), ...data];
  
  fs.writeFileSync(filePath, JSON.stringify(allRecords, null, 2));
  console.log(`Generated 30 days of realistic mock history for ${file}`);
});