// Copyright IBM Corp. 2012,2016. All Rights Reserved.
// Node module: foreman
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT

var fs   = require('fs');
var util = require('util');
var cons = require('./console').Console;

function method(name) {
  return function(o) {
    return o[name].apply(o);
  };
}

// Parse a Key=Value File Containing Environmental Variables
function keyValue(data) {
  var env = {};

  data
    .toString()
    .replace(/^\s*\#.*$/gm,'')
    .replace(/^\s*$/gm,'')
    .split(/\n/)
    .map(method('trim'))
    .filter(notBlank)
    .forEach(capturePair);

  return env;

  function notBlank(str) {
    return str.length > 2;
  }

  function capturePair(line) {
    var pair = line.split('=');
    var key = pair[0].trim();
    var rawVal = pair.slice(1).join('=').trim();
    env[key] = parseValue(rawVal);
  }

  function parseValue(val) {
    switch (val[0]) {
      case '"': return /^"([^"]*)"/.exec(val)[1];
      case "'": return /^'([^']*)'/.exec(val)[1];
      default : return val.replace(/\s*\#.*$/, '');
    }
  }
}

// Given:
/*
{
  "top": {
    "middle": {
      "bottom": "value"
    },
    "other": [ "zero", "one", "two" ]
  },
  "last": 42
}
*/
// Get:
/*
{
  "TOP_MIDDLE_BOTTOM": "value",
  "TOP_OTHER_0": "zero",
  "TOP_OTHER_1": "one",
  "TOP_OTHER_2": "two",
  "LAST": 42
}
*/
// Flatten nested object structure
function flattenJSON(json) {
  var flattened = {};

  walk(json, function(path, item) {
    flattened[path.join('_').toUpperCase()] = item;
  });

  return flattened;

  function walk(obj, visitor, path) {
    var item;
    path = path || [];
    for (var key in obj) {
      item = obj[key];
      if (typeof item === 'object') {
        walk(item, visitor, path.concat(key));
      } else {
        visitor(path.concat(key), item);
      }
    }
  }
}


// Given a standard dictionary:
/*
{
  "TOP_MIDDLE_BOTTOM": "value",
  "TOP_OTHER_0": "zero",
  "TOP_OTHER_1": "one",
  "TOP_OTHER_2": "two",
  "LAST": 42
}
*/
// Return a key=value pair document
/*
TOP_MIDDLE_BOTTOM=value
TOP_OTHER_0=zero
TOP_OTHER_1=one
TOP_OTHER_2=two
LAST=42
*/
function dumpEnv(conf) {
  var output = [];
  for (var key in conf) {
    output.push(key + '=' + conf[key]);
  }
  return output.sort().join('\n') + '\n';
}

// Loads a file as either a .env format or JSON format and returns it as a
// simplified dictionary
function loadEnvsFile(path) {
  var env, data;

  if(!fs.existsSync(path)) {
    env = {};
  } else {
    data = fs.readFileSync(path);
    try {
      var envs_json = JSON.parse(data);
      env = flattenJSON(envs_json, "", {});
      cons.Alert("Loaded ENV %s File as JSON Format", path);
    } catch (e) {
      env = keyValue(data);
      cons.Alert("Loaded ENV %s File as KEY=VALUE Format", path);
    }
  }
  env.PATH = env.PATH || process.env.PATH;
  return env;
}

function loadEnvs(path) {
  var envs = path.split(',').map(loadEnvsFile).reduce(util._extend, {});
  var sorted = Object.create(null);
  Object.keys(envs).sort().forEach(function(k) {
    sorted[k] = envs[k];
  });
  return sorted;
}

module.exports.loadEnvs = loadEnvs;
module.exports.flattenJSON = flattenJSON;
module.exports.keyValue = keyValue;
module.exports.dumpEnv  = dumpEnv;