const accentMap = {
    à: 'a',
    á: 'a',
    ä: 'a',
    å: 'a',
    ã: 'a',
    â: 'a',
    æ: 'ae',
    ç: 'c',
    è: 'e',
    é: 'e',
    ë: 'e',
    ẽ: 'e',
    ê: 'e',
    ì: 'i',
    í: 'i',
    ï: 'i',
    ĩ: 'i',
    î: 'i',
    ǹ: 'n',
    ń: 'n',
    ñ: 'n',
    ò: 'o',
    ó: 'o',
    ö: 'o',
    õ: 'o',
    ô: 'o',
    ø: 'o',
    œ: 'oe',
    ß: 'ss',
    ù: 'u',
    ú: 'u',
    ü: 'u',
    ũ: 'u',
    û: 'u',
    ỳ: 'y',
    ý: 'y',
    ÿ: 'y',
    ỹ: 'y',
};

const plainCharRegex = /[a-zA-Z0-9]/;
const defaultPunctuationRegex = /[.,?!:;&'‘’"“”…()[]{}<>\/*—-]/;
const defaultSymbolRegex = /[@$€£#%^+=\\~]/;

export default function slugify(strings, delimiter = '-', {
    limit = 1000,
    lower = true,
    encode = false,
    accents: keepAccents = false,
    punctuation: keepPunctuation = false,
    punctuationRegex = defaultPunctuationRegex,
    symbols: keepSymbols = false,
    symbolRegex = defaultSymbolRegex,
} = {}) {
    if (!strings || (typeof strings !== 'string' && !Array.isArray(strings))) {
        return strings;
    }

	const string = [].concat(strings).join(' ');

    const casedString = lower
        ? string.toLowerCase()
        : string;

    const normalized = casedString
        .split('')
        .map((char) => {
            if (char === ' ') {
                return char;
            }

            const lowChar = char.toLowerCase();

            if (accentMap[lowChar]) {
                if (keepAccents) {
                    return char;
                }

                // match original case after mapping
                if (char === lowChar) {
                    return accentMap[lowChar];
                }

                return accentMap[lowChar].toUpperCase();
            }

            if (plainCharRegex.test(char)) {
                return char;
            }

            if (punctuationRegex.test(char)) {
                if (keepPunctuation === 'split') {
                    return ' ';
                }

                if (keepPunctuation) {
                    return char;
                }
            }

            if (symbolRegex.test(char)) {
                if (keepSymbols === 'split') {
                    return ' ';
                }

                if (keepSymbols) {
                    return char;
                }
            }

            return '';
        }).join('');

    const components = normalized.trim().split(/\s+/).filter(Boolean);

    if (components.length === 0) {
        return '';
    }

    const slug = components.reduce((acc, component, index) => {
        const accSlug = `${acc}${index > 0 ? delimiter : ''}${component}`;

        if (accSlug.length < limit) {
            return accSlug;
        }

        return acc;
    }).slice(0, limit); // in case first word exceeds limit

    if (encode) {
        return encodeURI(slug);
    }

    return slug;
}