import * as fs from 'fs';
import * as json2csv from 'json2csv';

interface FlattenData {
    [key: string]: string | number | FlattenData;
}

function flattenJson(data: any, parentKey = '', separator = '.'): FlattenData {
    const flattenedData: FlattenData = {};
    for (const key in data) {
        if (data.hasOwnProperty(key)) {
            const newKey = parentKey ? `${parentKey}${separator}${key}` : key;
            if (typeof data[key] === 'object' && !Array.isArray(data[key])) {
                const nestedData = flattenJson(data[key], newKey, separator);
                Object.assign(flattenedData, nestedData);
            } else {
                flattenedData[newKey] = data[key];
            }
        }
    }
    return flattenedData;
}

export function createCsvFromJson(jsonData: string, csvFilePath: string): void {
    // Load JSON data
    const data = JSON.parse(jsonData);

    // Flatten JSON data
    const flattenedData = flattenJson(data);

    // Get headers from flattened data
    const headers = Object.keys(flattenedData);

    // Convert flattened data to array of objects for json2csv
    const rows = [flattenedData];

    // Create CSV file
    const csv = json2csv.parse(rows, { fields: headers });
    fs.writeFileSync(csvFilePath, csv);
    console.log(`CSV file created at: ${csvFilePath}`);
}

export function createCsvFromJsonArray(jsonDataArray: any[], csvFilePath: string): void {
    // Flatten JSON data in array
    const flattenedDataArray = jsonDataArray.map((data) => flattenJson(data));

    // Get headers from flattened data
    const headers = Array.from(
        new Set(flattenedDataArray.flatMap((data) => Object.keys(data)))
    );

    // Convert flattened data to array of objects for json2csv
    const rows = flattenedDataArray.map((data) => headers.reduce((obj, key) => {
        // @ts-ignore
        obj[key] = data[key] || '';
        return obj;
    }, {}));

    // Create CSV file
    const csv = json2csv.parse(rows, { fields: headers });
    fs.writeFileSync(csvFilePath, csv);
    console.log(`CSV file created at: ${csvFilePath}`);
}

// Example usage
// const jsonData = `{
//   "name": "John",
//   "age": 30,
//   "address": {
//     "street": "123 Main St",
//     "city": "New York",
//     "state": "NY",
//     "zip": "10001"
//   },
//   "phone": {
//     "home": "123-456-7890",
//     "work": "987-654-3210"
//   }
// }`;

// const csvFilePath = 'output.csv';
// createCsvFromJson(jsonData, csvFilePath);