import { Config } from './model';
import * as i0 from "@angular/core";
interface DataObject {
    [key: string]: string | number | boolean | null;
}
/**
 *
 * # Ngx Data To CSV
 *
 * usage:
 *
 * ```ts
 *  private service: NgxDataToCsvService = inject(NgxDataToCsvService);
 *  // or using constructor
 *  constructor(private service: NgxDataToCsvService) {}
 *
 *  onClick(data: MyDataType[]): void {
 *    this.service.toCsv(data, 'filename');
 *  }
 * ```
 * ## Description
 *
 * The NgxDataToCsvService class provides a service to transform data into CSV format.
 *
 * It provides methods to convert data (in the form of an object or a JSON string) into CSV format,
 * extract values from nested objects, extract unique keys from an array of objects,
 * parse a JSON string into an object, format cell values for inclusion in a CSV file,
 * and to initiate the download of a CSV file.
 *
 * The class maintains a private property `data` to hold the data to be transformed,
 * a private property `options` to hold the configuration for the CSV output,
 * and a private property `csv` to hold the resulting CSV string.
 *
 * The main method `toCsv` is public and can be used to transform data into CSV format.
 * It takes the data to be transformed, the desired filename for the CSV file,
 * and an optional configuration object as arguments. The configuration object allows for customizing
 * the CSV output, such as setting the field separator, showing a title, prepending a byte order mark,
 * and deciding whether to download the CSV file or return it as a string. The `toCsv` method also
 * orchestrates the extraction of unique keys, the formatting of cell values, and the downloading of the CSV file.
 *
 * The other methods are private helper methods used by the `toCsv` method.
 */
export declare class NgxDataToCsvService {
    private data;
    private options;
    private csv;
    /**
     * This method transforms the provided data into a CSV format.
     *
     * @param {any} dataToTransform - The data to be transformed. This can be either a JavaScript object or a JSON string.
     * @param {string} filename - The desired name for the resulting CSV file.
     * @param {Config} config - An optional configuration object for customizing the CSV output.
     *
     * The configuration object can contain the following keys:
     * - filename: the name of the CSV file.
     * - fieldSeparator: the character used to separate fields in the CSV.
     * - showTitle: a boolean that determines whether to display a title in the CSV.
     * - title: the title to display in the CSV.
     * - useByteOrderMark: a boolean that determines whether to prepend a byte order mark to the CSV.
     * - noDownload: a boolean that determines whether to download the CSV or return it as a string.
     *
     * @returns {string | void} - If noDownload is set to true in the config, returns the CSV as a string. Otherwise, triggers a download of the CSV file and returns void.
     */
    toCsv(dataToTransform: DataObject[], filename: string, config?: Config): string | void;
    /**
     * This method retrieves the value of a nested object property.
     *
     * @param {GenericObject} obj - The object from which to retrieve the value.
     * @param {string} key - The key used to locate the value. It supports a nested key in the form 'key1.key2.key3' or 'key1[index].key2'.
     *                        For example, for an object like `{ key1: { key2: { key3: 'value' }}}`, the method can be called with the key 'key1.key2.key3'.
     *                        Similarly, for an object like `{ key1: [{ key2: 'value' }] }`, the method can be called with the key 'key1[0].key2'.
     * @returns {any} - Returns the value of the specified key in the object. If the key is not found, it returns `undefined`.
     */
    private getNestedObjectValue;
    /**
     * This method extracts the unique keys from an array of objects.
     * It is designed to handle nested objects and arrays as well.
     *
     * @param {GenericObject[]} arr - The array of objects from which to extract the keys.
     * @param {string} keyPrefix - An optional prefix to prepend to each key. Defaults to an empty string.
     *
     * The function operates recursively to handle nested structures. If a key points to an array,
     * it recursively extracts keys from each item in the array. If a key points to an object, it recursively
     * extracts keys from the object. In the base case, when a key points to a primitive value, it adds the key
     * (with the current prefix) to the set of unique keys.
     *
     * @returns {string[]} - Returns an array of unique keys from the input array of objects.
     */
    private extractUniqueKeys;
    /**
     * This method attempts to parse a JSON string into an object.
     *
     * @param {string} jsonString - The JSON string to parse.
     *
     * The method uses the JSON.parse function to attempt to parse the input string.
     * If the parsing is successful and the result is an object, it returns the parsed object.
     * If the parsing fails or the result is not an object, it logs an error and returns null.
     *
     * @returns {GenericObject[] | null} - Returns the parsed object if the parsing is successful; otherwise, returns null.
     */
    private parseJson;
    /**
     * This method formats a cell value for inclusion in a CSV.
     *
     * @param {GenericObject} obj - The object containing the cell value.
     * @param {string} key - The key identifying the cell value within the object.
     *
     * The method retrieves the value from the object using the provided key.
     * If the value is an object itself, it stringifies it using JSON.stringify.
     * If the value contains any double-quote characters ("), it replaces them with two double-quote characters ("") to escape them in the CSV.
     * The method then wraps the value in double-quote characters and returns it.
     *
     * @returns {string} - Returns the cell value formatted for inclusion in a CSV.
     */
    private formatCellValue;
    /**
     * This method initiates the download of the CSV file.
     *
     * It first creates a new Blob object from the CSV string stored in this.csv, setting the Blob's MIME type to "text/csv;charset=utf8;".
     * It then creates a new 'a' element and sets its href attribute to a URL representing the Blob object.
     * The 'a' element's target attribute is set to '_blank' to open the download in a new tab or window, and its visibility is set to 'hidden' to avoid displaying it.
     * The 'a' element's download attribute is set to the filename specified in the options, with spaces replaced by underscores, and the extension ".csv" appended.
     * The 'a' element is then added to the document's body and its click method is called to start the download.
     * Finally, the 'a' element is removed from the document's body after the download has started.
     */
    private downloadCsvFile;
    /**
     * Adds the Byte Order Mark and title to the CSV string if specified in the options.
     *
     * The Byte Order Mark (BOM) is a Unicode character used to signal the endianness
     * (byte order) of a text. It's optional and not all CSV parsers require or understand it.
     *
     * The title is a user-defined string that will be placed at the top of the CSV file,
     * separated from the rest of the data by two newline characters.
     */
    private addByteOrderMarkAndTitle;
    /**
     * Generates the CSV header row and appends it to the CSV string.
     *
     * This method takes an array of keys, which represent the column headers in the CSV file,
     * and joins them together into a single string with the field separator defined in the options.
     * The field separator is typically a comma (,), but it could be any character.
     *
     * After joining the keys, an end of line marker is appended to complete the header row.
     *
     * @param keys An array of strings representing the column headers for the CSV file.
     */
    private generateCsvHeader;
    /**
     * Generates a CSV row from a given object and appends it to the CSV string.
     *
     * This method takes an object and an array of keys. The keys represent the fields
     * of the object that will be included in the CSV row. For each key, it retrieves
     * the corresponding value from the object, formats it using the `formatCellValue` method,
     * and then joins these formatted values into a single string with the field separator defined in the options.
     *
     * After joining the values, an end of line marker is appended to complete the row.
     *
     * @param obj The object to convert into a CSV row.
     * @param keys An array of strings representing the fields of the object to include in the CSV row.
     */
    private generateCsvRow;
    static ɵfac: i0.ɵɵFactoryDeclaration<NgxDataToCsvService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<NgxDataToCsvService>;
}
export {};