import * as fs from 'fs';

import * as path from 'path';

type EnvVars = Object & { [key: string]: string };

export function parseEnvFile(envFile: string, mergeWithProcessEnvVars: boolean = true): EnvVars {

const buffer = fs.readFileSync(envFile, 'utf8');

const env = {};

buffer.split('\n').forEach(line => {

const r = line.match(/^\s*([\w\.\-]+)\s*=\s*(.*)?\s*$/);

if (r !== null) {

let value = r[2] || '';

if (value.length > 0 && value.charAt(0) === '"' && value.charAt(value.length - 1) === '"') {

value = value.replace(/\\n/gm, '\n');

}

env[r[1]] = value.replace(/(^['"]|['"]$)/g, '');

}

});

return mergeWithProcessEnvVars ? mergeEnvVariables(env, process.env) : mergePythonPath(env, process.env.PYTHONPATH);

}

/**

* Merge the target environment variables into the source.

* Note: The source variables are modified and returned (i.e. it modifies value passed in).

* @export

* @param {EnvVars} targetEnvVars target environment variables.

* @param {EnvVars} [sourceEnvVars=process.env] source environment variables (defaults to current process variables).

* @returns {EnvVars}

*/

export function mergeEnvVariables(targetEnvVars: EnvVars, sourceEnvVars: EnvVars = process.env): EnvVars {

Object.keys(sourceEnvVars).forEach(setting => {

if (targetEnvVars[setting] === undefined) {

targetEnvVars[setting] = sourceEnvVars[setting];

}

});

return mergePythonPath(targetEnvVars, sourceEnvVars.PYTHONPATH);

}

/**

* Merge the target PYTHONPATH value into the env variables passed.

* Note: The env variables passed in are modified and returned (i.e. it modifies value passed in).

* @export

* @param {EnvVars} env target environment variables.

* @param {string | undefined} [currentPythonPath] PYTHONPATH value.

* @returns {EnvVars}

*/

export function mergePythonPath(env: EnvVars, currentPythonPath: string | undefined): EnvVars {

if (typeof currentPythonPath !== 'string' || currentPythonPath.length === 0) {

return env;

}

if (typeof env.PYTHONPATH === 'string' && env.PYTHONPATH.length > 0) {

env.PYTHONPATH = env.PYTHONPATH + path.delimiter + currentPythonPath;

} else {

env.PYTHONPATH = currentPythonPath;

}

return env;

}