import {Injectable} from '@angular/core';
import {PersianService} from './persian-service';
import {PersianNumberService} from './persian-number.service';

/**
 * IsPersian options parameter object should implement this interface. Fields descriptions are in the isPersian method document.
 */
export interface PLOptions {
    persianDigits?: boolean;
    enDigits?: boolean;
    symbols?: boolean;
    whitespaces?: boolean;
}

@Injectable({
    providedIn: 'root'
})
/**
 * This service brings validation of persian texts to the program and let you convert some not-persian letters with persian ones.
 *
 */
export class PersianLetterService implements PersianService {

    static PERSIAN_LETTERS_PATTERN = '\u06A9\u06AF\u06C0\u06CC\u060C\u062A\u062B\u062C\u062D\u062E\u062F\u063A\u064A\u064B\u064C' +
        '\u064D\u064E\u064F\u067E\u0670\u0686\u0698\u200C\u0621-\u0629\u0630-\u0639\u0641-\u0654';
    static WHITESPACES_PATTERN = '\\s';
    private static SYMBOLS_PATTERN = '؟$-/:-?،{-~!"^_`\\[\\]';

    /**
     * According to the options values, returns a RegExp object. The regex pattern of it contains regex of finding each of
     * elements those specified in the options object plus persian letters.
     *
     * @return a RegExp object that can use in searching a string for special characters (persian letters and others specified in the options)
     * @param options
     */
    private static _stringValidationRegex(options: PLOptions): RegExp {
        let result = '';
        if (options.enDigits) {
            result += '0-9';
        }
        if (options.symbols) {
            result += PersianLetterService.SYMBOLS_PATTERN;
        }
        if (options.whitespaces) {
            result += PersianLetterService.WHITESPACES_PATTERN;
        }
        if (options.persianDigits) {
            result += PersianNumberService.persianNumberPattern;
        }
        // Language=JSRegexp
        return new RegExp(`[${result + PersianLetterService.PERSIAN_LETTERS_PATTERN}]`, 'g');
    }

    /**
     * This method gets regex of persian letters and other chars specified in the options and then splits the input value by that regex.
     *
     * If match result is null - there is no match - returns 0. otherwise returns length of the match array that shows number of matched
     * occurred in the input value.
     *
     * @param value
     * @param options
     * @return a number greater equal to 0 representing number of matches occurred in the input value.
     */
    private static _getMatchedPatternLength(value: string, options: PLOptions): number {
        const matchResult = value.match(PersianLetterService._stringValidationRegex(options));
        return matchResult ? matchResult.length : 0;
    }

    /**
     * If input value contains any persian letter or is an empty string, returns true. otherwise returns false.
     *
     * @param value
     */
    containsPersian(value: string): boolean {
        // Language=JSRegexp
        const persianRegex = new RegExp(`[${PersianLetterService.PERSIAN_LETTERS_PATTERN}]`);
        return value.trim() ? persianRegex.test(value) : true;
    }

    /**
     * Checks if input value is a persian text or not. If input value contains any letter that is not persian, the output will be false.
     * Result of validation on existence  of other characters controls by options parameter.
     *
     * @param value
     * @param options controlling validation result on existence  of other characters controls by options parameter. Fields:
     *
     *        persianDigits: if sets to true, validation result will be true if input value contains persian digits plus persian letters.
     *
     *
     *        enDigits: if sets to true, validation result will be true if input value contains english digits plus persian letters
     *
     *
     *        symbols: if sets to true, validation result will be true if input value contains specific symbols plus persian letters.
     *                 symbols list: ?$-/:؟!~"'^_-[]{}()%&*><;
     *
     *
     *        whitespaces: if sets to true, validation result will be true if input value contains white spaces plus persian letters
     *
     *
     * You can combine any number of options field together.
     */
    isPersian(value: string, options: PLOptions = {
        persianDigits: false,
        enDigits: false,
        symbols: true,
        whitespaces: true
    }): boolean {
        return value.length === PersianLetterService._getMatchedPatternLength(value, options);
    }

    /**
     * Converts arabic letters: ي and ك to persian corresponding letters.
     *
     * @param value
     */
    toPersian(value: string): string {
        return value.replace(/ي/g, 'ی').replace(/ك/g, 'ک');
    }

}