@2o3t/koa2-proxy-middleware/lib/context-matcher.js

http proxy middleware for koa2

'use strict';

const url = require('url');
const utility = require('2o3t-utility');
const isFunction = utility.is.function;
const isGlob = utility.isGlob;
const micromatch = utility.micromatch;

const ERRORS = require('./errors');

module.exports = {
    match: matchContext,
};

function matchContext(context, uri, req) {
    // single path
    if (isStringPath(context)) {
        return matchSingleStringPath(context, uri);
    }

    // single glob path
    if (isGlobPath(context)) {
        return matchSingleGlobPath(context, uri);
    }

    // multi path
    if (Array.isArray(context)) {
        if (context.every(isStringPath)) {
            return matchMultiPath(context, uri);
        }
        if (context.every(isGlobPath)) {
            return matchMultiGlobPath(context, uri);
        }

        throw new Error(ERRORS.ERR_CONTEXT_MATCHER_INVALID_ARRAY);
    }

    // custom matching
    if (isFunction(context)) {
        const pathname = getUrlPathName(uri);
        return context(pathname, req);
    }

    throw new Error(ERRORS.ERR_CONTEXT_MATCHER_GENERIC);
}

/**
 * @param  {String} context '/api'
 * @param  {String} uri     'http://example.org/api/b/c/d.html'
 * @return {Boolean} bool
 */
function matchSingleStringPath(context, uri) {
    const pathname = getUrlPathName(uri);
    return pathname.indexOf(context) === 0;
}

function matchSingleGlobPath(pattern, uri) {
    const pathname = getUrlPathName(uri);
    const matches = micromatch(pathname, pattern);
    return matches && (matches.length > 0);
}

function matchMultiGlobPath(patternList, uri) {
    return matchSingleGlobPath(patternList, uri);
}

/**
 * @param  {String} contextList ['/api', '/ajax']
 * @param  {String} uri     'http://example.org/api/b/c/d.html'
 * @return {Boolean} bool
 */
function matchMultiPath(contextList, uri) {
    for (let i = 0; i < contextList.length; i++) {
        const context = contextList[i];
        if (matchSingleStringPath(context, uri)) {
            return true;
        }
    }
    return false;
}

/**
 * Parses URI and returns RFC 3986 path
 *
 * @param  {String} uri from req.url
 * @return {String}     RFC 3986 path
 */
function getUrlPathName(uri) {
    return uri && url.parse(uri).pathname;
}

function isStringPath(context) {
    return utility.isString(context) && !isGlob(context);
}

function isGlobPath(context) {
    return isGlob(context);
}