import { CSVParser, unparse, flatten } from "turbocsv";

// Robust parsing with error handling
const parser = new CSVParser("messy.csv", {
  trim: true,                     // Clean whitespace
  skipRecordsWithError: true,     // Skip bad rows
  comments: true,                  // Skip # prefixed lines
  duplicateHeaders: "rename",      // Handle duplicate columns
  dynamicTyping: true,             // Auto-convert types
  maxRecordSize: 10000,            // Reject huge rows
  cast: {                          // Custom transformers
    price: (val) => parseFloat(val.replace("$", "")),
    date: (val) => new Date(val)
  }
});

// Process with structured error handling
for (const row of parser) {
  try {
    processRow(row);
  } catch (error) {
    if (error.code === "TooFewFields") {
      console.log(`Row ${error.row}: Missing fields`);
    }
  }
}

// Secure CSV output
const csv = unparse(data, {
  escapeFormulae: true,    // Prevent CSV injection
  flattenObjects: true     // Handle nested JSON
});

import { CSVParser } from "turbocsv";

const parser = new CSVParser("data.csv");
const df = parser.toDataFrame();

// Chain operations
const result = df
  .filter(row => row.age > 18)
  .select("name", "email", "age")
  .sorted("name", "asc")
  .first(100);

// Aggregation
const grouped = df.groupBy("department", [
  { col: "salary", fn: "mean" },
  { col: "id", fn: "count" },
]);

parser.close();

# Trim whitespace and skip bad rows
turbocsv head --trim --skip-errors data.csv

# Fast mode with dynamic typing
turbocsv head --fast --dynamic-typing --format json data.csv

# Validate with structured error reporting
turbocsv validate data.csv
# Output: ERROR [TooFewFields] at row 42: Expected 5 fields, got 3

# Process specific range with comments
turbocsv head --from-line 5 --to-line 20 --comments data.csv

# Security: escape formula injection
turbocsv convert --escape-formulae data.csv -o safe.csv

# Handle duplicate headers
turbocsv head --duplicate-headers rename data.csv