import * as fs from 'fs';
import * as path from 'path';
import * as cheerio from 'cheerio';
import axios from 'axios';
import https from 'https';
import { lakesConfig } from './lakesConfig';

interface DataRecord {
  timestamp: string;
  level: number;
  flow: number;
  inflow?: number;
  volume?: number;
  temperature?: number | null;
  precipitation?: number | null;
}

// Parse date from DD.MM.YYYY HH:MM to ISO
export function parseDateString(dateStr: string): string | null {
  try {
    if (!dateStr || !dateStr.includes(' ')) return null;
    const [datePart, timePart] = dateStr.trim().split(' ');
    const [day, month, year] = datePart.split('.');
    const [hours, minutes] = timePart.split(':');
    
    if (!year || !hours) return null;
    
    const y = parseInt(year);
    const m = parseInt(month) - 1;
    const dDay = parseInt(day);
    const d = new Date(y, m, dDay, parseInt(hours), parseInt(minutes));
    if (isNaN(d.getTime())) return null;
    if (d.getFullYear() !== y || d.getMonth() !== m || d.getDate() !== dDay) return null;
    return d.toISOString();
  } catch (e) {
    return null;
  }
}

async function scrapeLake(lakeId: string, oid: string, internalId: string) {
  const URL = `https://www.pvl.cz/portal/nadrze/cz/pc/Mereni.aspx?oid=${oid}&id=${internalId}`;
  const DATA_FILE = path.resolve(`public/data/${internalId}.json`);

  try {
    const agent = new https.Agent({ rejectUnauthorized: false });
    const response = await axios.get(URL, {
      httpsAgent: agent,
      headers: {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36'
      }
    });

    const $ = cheerio.load(response.data);
      
    let currentInflow = 0;
    let currentVolume = 0;
    let currentTemp: number | null = null;
    let currentPrecip: number | null = null;
    
    $('table').each((i, tbl) => {
      const text = $(tbl).text();
      if (text.includes('Aktuální hodnoty') && text.includes('Přítok')) {
        $(tbl).find('tr').each((j, r) => {
          const label = $(r).find('td').eq(0).text().trim();
          const valStr = $(r).find('td').eq(1).text().trim().replace(/\s/g, '').replace(',', '.');
          if (label.includes('Přítok')) currentInflow = parseFloat(valStr) || 0;
          if (label.includes('Objem')) currentVolume = parseFloat(valStr) || 0;
          if (label.includes('Teplota')) {
            const v = parseFloat(valStr);
            if (!isNaN(v)) currentTemp = v;
          }
          if (label.includes('Srážky')) {
            const v = parseFloat(valStr);
            if (!isNaN(v)) currentPrecip = v;
          }
        });
      }
    });

    const records: DataRecord[] = [];
    let dataTable = null;
    $('table').each((i, tbl) => {
      if ($(tbl).text().includes('Datum') && $(tbl).text().includes('Odtok')) {
        dataTable = $(tbl);
      }
    });

    if (dataTable) {
      dataTable.find('tr').each((i, row) => {
        if (i === 0) return; // skip header
        const cols = $(row).find('td');
        if (cols.length >= 3) {
          const rawDate = $(cols[0]).text().trim(); 
          const levelStr = $(cols[1]).text().trim().replace(',', '.');
          let flowStr = $(cols[2]).text().trim().replace(',', '.');
          if (flowStr === '' && cols.length >= 4) {
            flowStr = $(cols[3]).text().trim().replace(',', '.');
          }

          const parsedDateStr = parseDateString(rawDate);
          if (parsedDateStr) {
            records.push({
              timestamp: parsedDateStr,
              level: parseFloat(levelStr) || 0,
              flow: parseFloat(flowStr) || 0,
              inflow: 0,
              volume: 0
            });
          }
        }
      });
    }

    if (records.length > 0) {
      // Apply current values to the latest record
      records[0].inflow = currentInflow;
      records[0].volume = currentVolume;
      if (currentTemp !== null) records[0].temperature = currentTemp;
      if (currentPrecip !== null) records[0].precipitation = currentPrecip;
    }

    let existingData: DataRecord[] = [];
    if (fs.existsSync(DATA_FILE)) {
      const fileContent = fs.readFileSync(DATA_FILE, 'utf-8');
      existingData = JSON.parse(fileContent);
    }

    const dataMap = new Map<string, DataRecord>();
    existingData.forEach(item => dataMap.set(item.timestamp, item));
    records.forEach(item => dataMap.set(item.timestamp, item));

    const mergedData = Array.from(dataMap.values()).sort((a, b) => {
      return new Date(a.timestamp).getTime() - new Date(b.timestamp).getTime();
    });

    // Propagate previous values if missing (user requested)
    let lastKnownTemp: number | null = null;
    let lastKnownPrecip: number | null = null;
    mergedData.forEach(item => {
      if (item.temperature !== undefined && item.temperature !== null) {
        lastKnownTemp = item.temperature;
      } else if (lastKnownTemp !== null) {
        item.temperature = lastKnownTemp;
      }

      if (item.precipitation !== undefined && item.precipitation !== null) {
        lastKnownPrecip = item.precipitation;
      } else if (lastKnownPrecip !== null) {
        item.precipitation = lastKnownPrecip;
      }
    });

    fs.mkdirSync(path.dirname(DATA_FILE), { recursive: true });
    fs.writeFileSync(DATA_FILE, JSON.stringify(mergedData, null, 2), 'utf-8');
    
    console.log(`[${internalId}] Scraped ${records.length} records. DB total: ${mergedData.length}`);

  } catch (error: any) {
    console.error(`[${internalId}] Error scraping data:`, error.message);
  }
}

async function runScraper() {
  console.log(`Starting bulk scraper for ${lakesConfig.length} lakes...`);
  
  for (const lake of lakesConfig) {
    // ID format: VLL1|1 -> internalId=VLL1, oid=1
    const [internalId, oid] = lake.id.split('|');
    await scrapeLake(lake.id, oid, internalId);
    // Add small delay to not hammer the server
    await new Promise(resolve => setTimeout(resolve, 500));
  }
  
  console.log('Bulk scraping finished.');
}

runScraper();