Function detectColumnTypes

frontend/src/hooks/stream/useStreamingCSVParser.ts:31–75

(data: string[][], headers: string[])

   * Detect column types from a sample of data rows
   */
  const detectColumnTypes = (data: string[][], headers: string[]): ColumnType[] => {
    if (!data || data.length === 0 || !headers) return [];
    
    const types = Array(headers.length).fill(ColumnType.Unknown);
    
    // Process rows to detect types
    for (const row of data) {
      for (let j = 0; j < Math.min(row.length, headers.length); j++) {
        const value = row[j]?.trim();
        if (!value) continue;
        
        // If already detected as text, no need to check further
        if (types[j] === ColumnType.Text) continue;
        
        // Try to parse as number
        if (!isNaN(Number(value)) && value !== '') {
          if (types[j] === ColumnType.Unknown) {
            types[j] = ColumnType.Number;
          }
          continue;
        }
        
        // Try to parse as boolean
        if (/^(true|false|yes|no)$/i.test(value)) {
          if (types[j] === ColumnType.Unknown) {
            types[j] = ColumnType.Boolean;
          }
          continue;
        }
        
        // Try to parse as date
        if (/^\d{1,4}[-/]\d{1,2}[-/]\d{1,4}/.test(value)) {
          if (types[j] === ColumnType.Unknown || types[j] === ColumnType.Number) {
            types[j] = ColumnType.Date;
          }
          continue;
        }
        
        // Default to text
        types[j] = ColumnType.Text;
      }
    }
    
    return types;
  };

  /**
   * Parse large CSV files in chunks with progress tracking and browser yielding