lib/properties.js

// Copyright (c) 2012-2018, Matt Godbolt
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions are met:
// 
//     * Redistributions of source code must retain the above copyright notice, 
//       this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright 
//       notice, this list of conditions and the following disclaimer in the 
//       documentation and/or other materials provided with the distribution.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
// POSSIBILITY OF SUCH DAMAGE.

const fs = require('fs'),
    logger = require('./logger').logger,
    _ = require('underscore-node'),
    path = require('path');

let properties = {};

let hierarchy = [];

let propDebug = false;

function findProps(base, elem) {
    const name = base + '.' + elem;
    return properties[name];
}

function debug(string) {
    if (propDebug) logger.info(`prop: ${string}`);
}

function get(base, property, defaultValue) {
    let result = defaultValue;
    let source = 'default';
    hierarchy.forEach(elem => {
        const propertyMap = findProps(base, elem);
        if (propertyMap && property in propertyMap) {
            debug(`${base}.${property}: overriding ${source} value (${result}) with ${propertyMap[property]}`);
            result = propertyMap[property];
            source = elem;
        }
    });
    debug(`${base}.${property}: returning ${result} (from ${source})`);
    return result;
}

function toProperty(prop) {
    if (prop === 'true' || prop === 'yes') return true;
    if (prop === 'false' || prop === 'no') return false;
    if (prop.match(/^-?[0-9]+$/)) return parseInt(prop);
    if (prop.match(/^-?[0-9]*\.[0-9]+$/)) return parseFloat(prop);
    return prop;
}

function parseProperties(blob, name) {
    const props = {};
    blob.split('\n').forEach((line, index) => {
        line = line.replace(/#.*/, '').trim();
        if (!line) return;
        let split = line.match(/([^=]+)=(.*)/);
        if (!split) {
            logger.error(`Bad line: ${line} in ${name}: ${index + 1}`);
            return;
        }
        props[split[1].trim()] = toProperty(split[2].trim());
        debug(`${split[1].trim()} = ${split[2].trim()}`);
    });
    return props;
}

function initialize(directory, hier) {
    if (hier === null) throw new Error('Must supply a hierarchy array');
    hierarchy = _.map(hier, x => x.toLowerCase());
    logger.info(`Reading properties from ${directory} with hierarchy ${hierarchy}`);
    const endsWith = /\.properties$/;
    const propertyFiles = fs.readdirSync(directory).filter(filename => filename.match(endsWith));
    properties = {};
    propertyFiles.forEach(file => {
        const baseName = file.replace(endsWith, '');
        file = path.join(directory, file);
        debug('Reading config from ' + file);
        properties[baseName] = parseProperties(fs.readFileSync(file, 'utf-8'), file);
    });
    logger.debug("props.properties = ", properties);
}

function propsFor(base) {
    return function (property, defaultValue) {
        return get(base, property, defaultValue);
    };
}

module.exports = {
    get: get,
    propsFor: propsFor,
    initialize: initialize,
    setDebug: function (debug) {
        propDebug = debug;
    },
    fakeProps: fake => (prop, def) => fake[prop] === undefined ? def : fake[prop]
};