import * as hljs from 'highlight.js/lib/highlight';
import * as javascript from 'highlight.js/lib/languages/javascript';
import * as json from 'highlight.js/lib/languages/json';

hljs.registerLanguage('javascript', javascript);
hljs.registerLanguage('json', json);

interface PatchInterface {
    [key: string]: string;
}

const PATCH_TYPES: PatchInterface = {
    '+': 'addition',
    '-': 'deletion',
    '!': 'change',
};

function diffHighlight(language: string, code: any, gutter: any): string {
    return code
        .split(/\r?\n/g)
        .map((line: string, index: number) => {
            let type;
            let currentLine = line;

            if (/^-{3} [^-]+ -{4}$|^\*{3} [^*]+ \*{4}$|^@@ [^@]+ @@$/.test(currentLine)) {
                type = 'chunk';
            } else if (/^Index: |^[+\-*]{3}|^[*=]{5,}$/.test(currentLine)) {
                type = 'header';
            } else {
                type = PATCH_TYPES[currentLine[0]] || 'null';
                currentLine = currentLine.replace(/^[+\-! ]/, '');
            }

            const g = gutter[index];

            return `<span data-gutter="${g !== undefined ? `${g}x` : ''}" class="line-${type}">${
                hljs.highlight(language, currentLine).value
            }</span>`;
        })
        .join('\n');
}

interface HighlightProps {
    language: string;
    code: string;
    isDiff?: boolean;
    gutter?: [];
    isEtc?: boolean;
}

function highlight({ language, code, isDiff, gutter, isEtc }: HighlightProps): string {
    if (isDiff) {
        return diffHighlight(language, code, gutter);
    }

    const hlCode = hljs.highlight(language, code).value;

    if (!isEtc) {
        return hlCode;
    }

    const hc = hlCode.split(/\r?\n/g);
    hc.splice(1, 0, '    ...');
    hc.splice(hc.length - 1, 0, '    ...');

    return hc.join('\n');
}

export { highlight };
