source: trip-planner-front/node_modules/read-cache/index.js@ b738035

var fs = require('fs');
var path = require('path');
var pify = require('pify');

var stat = pify(fs.stat);
var readFile = pify(fs.readFile);
var resolve = path.resolve;

var cache = Object.create(null);

function convert(content, encoding) {
        if (Buffer.isEncoding(encoding)) {
                return content.toString(encoding);
        }
        return content;
}

module.exports = function (path, encoding) {
        path = resolve(path);

        return stat(path).then(function (stats) {
                var item = cache[path];

                if (item && item.mtime.getTime() === stats.mtime.getTime()) {
                        return convert(item.content, encoding);
                }

                return readFile(path).then(function (data) {
                        cache[path] = {
                                mtime: stats.mtime,
                                content: data
                        };

                        return convert(data, encoding);
                });
        }).catch(function (err) {
                cache[path] = null;
                return Promise.reject(err);
        });
};

module.exports.sync = function (path, encoding) {
        path = resolve(path);

        try {
                var stats = fs.statSync(path);
                var item = cache[path];

                if (item && item.mtime.getTime() === stats.mtime.getTime()) {
                        return convert(item.content, encoding);
                }

                var data = fs.readFileSync(path);

                cache[path] = {
                        mtime: stats.mtime,
                        content: data
                };

                return convert(data, encoding);
        } catch (err) {
                cache[path] = null;
                throw err;
        }

};

module.exports.get = function (path, encoding) {
        path = resolve(path);
        if (cache[path]) {
                return convert(cache[path].content, encoding);
        }
        return null;
};

module.exports.clear = function () {
        cache = Object.create(null);
};