const fs = require('fs');
const d3 = require('d3');

// Read the CSV file
const csvFilePath = 'gaza-death-tolls.csv';

try {
  // Read the CSV file content
  const csvContent = fs.readFileSync(csvFilePath, 'utf8');
  
  // Parse the CSV using D3
  const data = d3.csvParse(csvContent);
  
  console.log('CSV Validation Results:');
  console.log('======================');
  
  // Basic validation checks
  console.log(`✓ File successfully parsed`);
  console.log(`✓ Number of rows: ${data.length}`);
  
  if (data.length > 0) {
    console.log(`✓ Number of columns: ${data.columns.length}`);
    console.log(`✓ Column names: ${data.columns.join(', ')}`);
    
    // Check for empty rows
    const emptyRows = data.filter(row => 
      Object.values(row).every(value => value === '' || value === null || value === undefined)
    );
    
    if (emptyRows.length > 0) {
      console.log(`⚠ Warning: ${emptyRows.length} empty rows found`);
    } else {
      console.log(`✓ No empty rows found`);
    }
    
    // Check for missing values in each column
    data.columns.forEach(column => {
      const rowsWithMissingValues = data.filter(row => 
        row[column] === '' || row[column] === null || row[column] === undefined
      );
      
      if (rowsWithMissingValues.length > 0) {
        console.log(`⚠ Warning: Column "${column}" has ${rowsWithMissingValues.length} missing values`);
        console.log(`Rows with missing "${column}" values:`);
        rowsWithMissingValues.forEach((row, index) => {
          console.log(`  Missing value row ${index + 1}:`, JSON.stringify(row, null, 2));
        });
      } else {
        console.log(`✓ Column "${column}" has no missing values`);
      }
    });
    
    // Display first few rows as sample
    console.log('\nSample data (first 3 rows):');
    console.log('============================');
    data.slice(0, 3).forEach((row, index) => {
      console.log(`Row ${index + 1}:`, row);
    });
    
  } else {
    console.log('⚠ Warning: CSV file appears to be empty or contains no data rows');
  }
  
} catch (error) {
  console.error('❌ Error validating CSV file:');
  
  if (error.code === 'ENOENT') {
    console.error(`File not found: ${csvFilePath}`);
    console.error('Please ensure the file exists in the current directory.');
  } else if (error.message.includes('CSV')) {
    console.error('CSV parsing error:', error.message);
  } else {
    console.error('Unexpected error:', error.message);
  }
  
  process.exit(1);
}