'use strict';

/**
 * Serverless Function Class
 * - options.path format is: "component/cPath/functionFolder"
 * - cPath is for component path.  You can nest functions in any amounts of subfolders (these subfolders are the cPath)
 * - But you must use '/' to divide subfolders.  E.g., restApi/data/users/show
 * - In the example, data/users is the component path.  The 'cPath'
 */

const SError   = require('./ServerlessError'),
  SUtils       = require('./utils/index'),
  BbPromise    = require('bluebird'),
  async        = require('async'),
  path         = require('path'),
  fs           = require('fs'),
  _            = require('lodash');

class ServerlessFunction {

  /**
   * Constructor
   */

  constructor(Serverless, config) {

    // Validate required attributes
    if (!config.component || !config.function) throw new SError('Missing required config.component or config.function');

    let _this        = this;
    _this._S         = Serverless;
    _this._config    = {};
    _this.updateConfig(config);

    // Default properties
    _this.name       = _this._config.function || 'function' + SUtils.generateShortId(6);
    _this.handler    = path.posix.join(
      _this._config.cPath ? _this._config.cPath.split('/').join(path.sep) : null,
      _this._config.function,
      'handler.handler');
    _this.timeout    = 6;
    _this.memorySize = 1024;
    _this.custom     = {
      excludePatterns: [],
      envVars:         []
    };
    _this.endpoints  = [];
    _this.endpoints.push(new _this._S.classes.Endpoint(_this._S, {
      component:      _this._config.component,
      cPath:          _this._config.cPath,
      function:       _this._config.function,
      endpointPath:   _this._config.cPath ? _this._config.cPath + '/' + _this._config.function : _this._config.function,
      endpointMethod: 'GET'
    }));
    _this.templates  = {};
  }

  /**
   * Set
   * - Set data
   * - Accepts a data object
   */

  set(data) {
    let _this = this;

    // Instantiate Components
    for (let i = 0; i < data.endpoints.length; i++) {

      if (data.endpoints[i] instanceof _this._S.classes.Endpoint) {
        throw new SError('You cannot pass subclasses into the set method, only object literals');
      }

      let instance = new _this._S.classes.Endpoint(_this._S, {
        component:       _this._config.component,
        cPath:           _this._config.cPath,
        function:        _this.name,
        endpointPath:    _this._config.cPath ? _this._config.cPath + '/' + _this._config.function : _this._config.function,
        endpointMethod:  data.endpoints[i].method
      });
      data.endpoints[i] = instance.set(data.endpoints[i]);
    }

    // Merge
    _.assign(_this, data);
    return _this;
  }

  /**
   * Update Config
   * - Takes config.component, config.cPath, config.function
   */

  updateConfig(config) {

    if (!config) return;

    // Check cPath separators
    if (config.cPath.indexOf('\\') !== -1) throw new SError('Cannot use "\\" in config.cPath');

    // Set sPath
    if (config.component || config.cPath || config.function) {
      this._config.component  = config.component;
      this._config.function   = config.function;
      this._config.cPath      = config.cPath ? config.cPath : null;
      this._config.sPath      = SUtils.buildSPath({
        component: config.component,
        cPath:     config.cPath,
        function:  config.function
      });
    }

    // Make full path
    if (this._S.config.projectPath && this._config.sPath) {
      let parse             = SUtils.parseSPath(this._config.sPath);
      this._config.fullPath = path.join(
        this._S.config.projectPath,
        parse.component,
        parse.cPath ? parse.cPath.split('/').join(path.sep) : null,
        parse.function
      );
    }
  }

  /**
   * Load
   * - Load from source (i.e., file system);
   * - Returns Promise
   */

  load() {

    let _this = this,
      functionJson;

    return BbPromise.try(function() {

        // Validate: Check project path is set
        if (!_this._S.config.projectPath) throw new SError('Function could not be loaded because no project path has been set on Serverless instance');

        // Validate: Check function exists
        if (!SUtils.fileExistsSync(path.join(_this._config.fullPath, 's-function.json'))) {
          throw new SError('Function could not be loaded because it does not exist in your project: ' + _this._config.sPath);
        }

        functionJson = SUtils.readAndParseJsonSync(path.join(_this._config.fullPath, 's-function.json'));

        return functionJson.endpoints;
      })
      .each(function(e, i) {

        // Add Endpoint Class Instances
        functionJson.endpoints[i] = new _this._S.classes.Endpoint(_this._S, {
          component:      _this._config.component,
          cPath:          _this._config.cPath,
          function:       functionJson.name,
          endpointPath:   e.path,
          endpointMethod: e.method
        });

        return functionJson.endpoints[i].load()
          .then(function(instance) {
            functionJson.endpoints[i] = instance;
            return functionJson.endpoints[i];
          });
      })
      .then(function() {

        // Get templates
        if (_this._config.fullPath && SUtils.fileExistsSync(path.join(_this._config.fullPath, 's-templates.json'))) {
          functionJson.templates = require(path.join(_this._config.fullPath, 's-templates.json'));
        }
      })
      .then(function() {

        // Merge
        _.assign(_this, functionJson);
        return _this;
      });
  }

  /**
   * Get
   * - Return data
   */

  get() {

    let _this = this;

    let clone  = _.cloneDeep(_this);
    for (let i = 0; i < _this.endpoints.length; i++) {
      clone.endpoints[i] = _this.endpoints[i].get();
    }
    return SUtils.exportClassData(clone);
  }

  /**
   * getPopulated
   * - Fill in templates then variables
   * - Returns Promise
   */

  getPopulated(options) {

    let _this = this;

    options = options || {};

    // Validate: Check Stage & Region
    if (!options.stage || !options.region) throw new SError('Both "stage" and "region" params are required');

    // Validate: Check project path is set
    if (!_this._S.config.projectPath) throw new SError('Function could not be populated because no project path has been set on Serverless instance');

    // Populate
    let clone       = _this.get();
    clone           = SUtils.populate(_this._S.state.getMeta(), _this.getTemplates(), clone, options.stage, options.region);
    clone.endpoints = [];
    for (let i = 0; i < _this.endpoints.length; i++) {
      clone.endpoints[i] = _this.endpoints[i].getPopulated(options);
    }
    return clone;

  }

  /**
   * Get Templates
   * - Returns clone of templates
   * - Inherits parent templates
   */

  getTemplates() {
    return _.merge(
      this.getProject().getTemplates(),
      this.getComponent().getTemplates(),
      _.cloneDeep(this.templates)
    );
  }

  /**
   * Save
   * - Saves data to file system
   * - Returns promise
   */

  save(options) {

    let _this = this;

    return new BbPromise.try(function() {

      // Validate: Check project path is set
      if (!_this._S.config.projectPath) throw new SError('Function could not be saved because no project path has been set on Serverless instance');

      // Create if does not exist
      if (!SUtils.fileExistsSync(path.join(_this._config.fullPath, 's-function.json'))) {
        return _this._create();
      }
    })
      .then(function() {

        // Save all nested endpoints
        if (options && options.deep) {
          return BbPromise.try(function () {
              return _this.endpoints;
            })
            .each(function(endpoint) {
              return endpoint.save();
            })
        }
      })
      .then(function() {

        // If templates, save templates
        if (_this.templates && Object.keys(_this.templates).length) {
          return SUtils.writeFile(path.join(_this._config.fullPath, 's-templates.json'), _this.templates);
        }
      })
      .then(function() {

        let clone = _this.get();

        // Strip properties
        if (clone.templates) delete clone.templates;

        // Write file
        return SUtils.writeFile(path.join(_this._config.fullPath, 's-function.json'),
          JSON.stringify(clone, null, 2));
      })
      .then(function() {
        return _this;
      })
  }

  /**
   * Create (scaffolding)
   * - Returns promise
   */

  _create() {

    let _this = this;

    return BbPromise.try(function() {

      let writeDeferred = [];

      // Runtime: nodejs
      writeDeferred.push(
        fs.mkdirSync(_this._config.fullPath),
        SUtils.writeFile(path.join(_this._config.fullPath, 'event.json'), '{}')
      )
      if (_this.getRuntime() === 'nodejs') {
        writeDeferred.push(
          SUtils.writeFile(path.join(_this._config.fullPath, 'handler.js'), fs.readFileSync(path.join(_this._S.config.serverlessPath, 'templates', 'nodejs', 'handler.js')))
        )
      } else if (_this.getRuntime() === 'python2.7') {
        writeDeferred.push(
          SUtils.writeFile(path.join(_this._config.fullPath, 'handler.py'), fs.readFileSync(path.join(_this._S.config.serverlessPath, 'templates', 'python2.7', 'handler.py')))
        )
      }
      return BbPromise.all(writeDeferred);

    });
  }

  getRuntime() {
    let _this     = this;
    let component = _this._S.state.getComponents({ paths: [_this._config.component] })[0];
    if (!component) throw new SError('The component containing runtime information for this function could not be found');
    return component.runtime;
  }

  /**
   * Get Project
   * - Returns reference to the instance
   */

  getProject() {
    return this._S.state.project;
  }

  /**
   * Get Component
   * - Returns reference to the instance
   */

  getComponent() {

    let components = this._S.state.getComponents({
      component: this._config.component
    });

    if (components.length === 1) {
      return components[0];
    }

    throw new SError('Could not find component for endpoint');
  }
}

module.exports = ServerlessFunction;