'use strict';

/**
 * Dependencies
 */
const EmailAddress = require('./email-address');
const Personalization = require('./personalization');
const toCamelCase = require('../helpers/to-camel-case');
const toSnakeCase = require('../helpers/to-snake-case');
const deepClone = require('../helpers/deep-clone');
const arrayToJSON = require('../helpers/array-to-json');
const { DYNAMIC_TEMPLATE_CHAR_WARNING } = require('../constants');
const {validateMailSettings, validateTrackingSettings} = require('../helpers/validate-settings');

/**
 * Mail class
 */
class Mail {

  /**
   * Constructor
   */
  constructor(data) {

    //Initialize array and object properties
    this.isDynamic = false;
    this.hideWarnings = false;
    this.personalizations = [];
    this.attachments = [];
    this.content = [];
    this.categories = [];
    this.headers = {};
    this.sections = {};
    this.customArgs = {};
    this.trackingSettings = {};
    this.mailSettings = {};
    this.asm = {};

    //Helper properties
    this.substitutions = null;
    this.substitutionWrappers = null;
    this.dynamicTemplateData = null;

    //Process data if given
    if (data) {
      this.fromData(data);
    }
  }

  /**
   * Build from data
   */
  fromData(data) {

    //Expecting object
    if (typeof data !== 'object') {
      throw new Error('Expecting object for Mail data');
    }

    //Convert to camel case to make it workable, making a copy to prevent
    //changes to the original objects
    data = deepClone(data);
    data = toCamelCase(data, ['substitutions', 'dynamicTemplateData', 'customArgs', 'headers', 'sections']);

    //Extract properties from data
    const {
      to, from, replyTo, cc, bcc, sendAt, subject, text, html, content,
      templateId, personalizations, attachments, ipPoolName, batchId,
      sections, headers, categories, category, customArgs, asm, mailSettings,
      trackingSettings, substitutions, substitutionWrappers, dynamicTemplateData, isMultiple,
      hideWarnings,
    } = data;

    //Set data
    this.setFrom(from);
    this.setReplyTo(replyTo);
    this.setSubject(subject);
    this.setSendAt(sendAt);
    this.setTemplateId(templateId);
    this.setBatchId(batchId);
    this.setIpPoolName(ipPoolName);
    this.setAttachments(attachments);
    this.setContent(content);
    this.setSections(sections);
    this.setHeaders(headers);
    this.setCategories(category);
    this.setCategories(categories);
    this.setCustomArgs(customArgs);
    this.setAsm(asm);
    this.setMailSettings(mailSettings);
    this.setTrackingSettings(trackingSettings);
    this.setHideWarnings(hideWarnings);

    if (this.isDynamic) {
      this.setDynamicTemplateData(dynamicTemplateData);
    } else {
      this.setSubstitutions(substitutions);
      this.setSubstitutionWrappers(substitutionWrappers);
    }

    //Add contents from text/html properties
    this.addTextContent(text);
    this.addHtmlContent(html);

    //Using "to" property for personalizations
    if (personalizations) {
      this.setPersonalizations(personalizations);
    } else if (isMultiple && Array.isArray(to)) {
      //Multiple individual emails
      to.forEach(to => this.addTo(to, cc, bcc));
    } else {
      //Single email (possibly with multiple recipients in the to field)
      this.addTo(to, cc, bcc);
    }
  }

  /**
   * Set from email
   */
  setFrom(from) {
    if (this._checkProperty('from', from, [this._checkUndefined])) {
      if (typeof from !== 'string' && typeof from.email !== 'string') {
        throw new Error('String or address object expected for `from`');
      }
      this.from = EmailAddress.create(from);
    }
  }

  /**
   * Set reply to
   */
  setReplyTo(replyTo) {
    if (this._checkProperty('replyTo', replyTo, [this._checkUndefined])) {
      if (typeof replyTo !== 'string' && typeof replyTo.email !== 'string') {
        throw new Error('String or address object expected for `replyTo`');
      }
      this.replyTo = EmailAddress.create(replyTo);
    }
  }

  /**
   * Set subject
   */
  setSubject(subject) {
    this._setProperty('subject', subject, 'string');
  }

  /**
   * Set send at
   */
  setSendAt(sendAt) {
    if (this._checkProperty('sendAt', sendAt, [this._checkUndefined, this._createCheckThatThrows(Number.isInteger, 'Integer expected for `sendAt`')])) {
      this.sendAt = sendAt;
    }
  }

  /**
   * Set template ID, also checks if the template is dynamic or legacy
   */
  setTemplateId(templateId) {
    if (this._setProperty('templateId', templateId, 'string')) {
      if (templateId.indexOf('d-') === 0) {
        this.isDynamic = true;
      }
    }
  }

  /**
   * Set batch ID
   */
  setBatchId(batchId) {
    this._setProperty('batchId', batchId, 'string');
  }

  /**
   * Set IP pool name
   */
  setIpPoolName(ipPoolName) {
    this._setProperty('ipPoolName', ipPoolName, 'string');
  }

  /**
   * Set ASM
   */
  setAsm(asm) {
    if (this._checkProperty('asm', asm, [this._checkUndefined, this._createTypeCheck('object')])) {
      if (typeof asm.groupId !== 'number') {
        throw new Error('Expected `asm` to include an integer in its `groupId` field');
      }
      if (asm.groupsToDisplay &&
        (!Array.isArray(asm.groupsToDisplay) || !asm.groupsToDisplay.every(group => typeof group === 'number'))) {
        throw new Error('Array of integers expected for `asm.groupsToDisplay`');
      }
      this.asm = asm;
    }
  }

  /**
   * Set personalizations
   */
  setPersonalizations(personalizations) {
    if (!this._doArrayCheck('personalizations', personalizations)) {
      return;
    }

    if (!personalizations.every(personalization => typeof personalization === 'object')) {
      throw new Error('Array of objects expected for `personalizations`');
    }

    //Clear and use add helper to add one by one
    this.personalizations = [];
    personalizations
      .forEach(personalization => this.addPersonalization(personalization));
  }

  /**
   * Add personalization
   */
  addPersonalization(personalization) {
    //We should either send substitutions or dynamicTemplateData
    //depending on the templateId
    if (this.isDynamic && personalization.substitutions) {
      delete personalization.substitutions;
    } else if (!this.isDynamic && personalization.dynamicTemplateData) {
      delete personalization.dynamicTemplateData;
    }

    //Convert to class if needed
    if (!(personalization instanceof Personalization)) {
      personalization = new Personalization(personalization);
    }

    //If this is dynamic, set dynamicTemplateData, or set substitutions
    if (this.isDynamic) {
      this.applyDynamicTemplateData(personalization);
    } else {
      this.applySubstitutions(personalization);
    }

    //Push personalization to array
    this.personalizations.push(personalization);
  }

  /**
   * Convenience method for quickly creating personalizations
   */
  addTo(to, cc, bcc) {
    if (
      typeof to === 'undefined' &&
      typeof cc === 'undefined' &&
      typeof bcc === 'undefined'
    ) {
      throw new Error('Provide at least one of to, cc or bcc');
    }
    this.addPersonalization(new Personalization({to, cc, bcc}));
  }

  /**
   * Set substitutions
   */
  setSubstitutions(substitutions) {
    this._setProperty('substitutions', substitutions, 'object');
  }

  /**
   * Set substitution wrappers
   */
  setSubstitutionWrappers(substitutionWrappers) {
    let lengthCheck = (propertyName, value) => {
      if (!Array.isArray(value) || value.length !== 2) {
        throw new Error('Array expected with two elements for `' + propertyName + '`');
      }
    };

    if (this._checkProperty('substitutionWrappers', substitutionWrappers, [this._checkUndefined, lengthCheck])) {
      this.substitutionWrappers = substitutionWrappers;
    }
  }

  /**
   * Helper which applies globally set substitutions to personalizations
   */
  applySubstitutions(personalization) {
    if (personalization instanceof Personalization) {
      personalization.reverseMergeSubstitutions(this.substitutions);
      personalization.setSubstitutionWrappers(this.substitutionWrappers);
    }
  }

  /**
   * Helper which applies globally set dynamic_template_data to personalizations
   */
  applyDynamicTemplateData(personalization) {
    if (personalization instanceof Personalization) {
      personalization.deepMergeDynamicTemplateData(this.dynamicTemplateData);
    }
  }

  /**
   * Set dynamicTemplateData
   */
  setDynamicTemplateData(dynamicTemplateData) {
    if (typeof dynamicTemplateData === 'undefined') {
      return;
    }
    if (typeof dynamicTemplateData !== 'object') {
      throw new Error('Object expected for `dynamicTemplateData`');
    }

    // Check dynamic template for non-escaped characters and warn if found
    if (!this.hideWarnings) {
      Object.values(dynamicTemplateData).forEach(value => {
        if (/['"&]/.test(value)) {
          console.warn(DYNAMIC_TEMPLATE_CHAR_WARNING);
        }
      });
    }

    this.dynamicTemplateData = dynamicTemplateData;
  }

  /**
   * Set content
   */
  setContent(content) {
    if (this._doArrayCheck('content', content)) {
      if (!content.every(contentField => typeof contentField === 'object')) {
        throw new Error('Expected each entry in `content` to be an object');
      }
      if (!content.every(contentField => typeof contentField.type === 'string')) {
        throw new Error('Expected each `content` entry to contain a `type` string');
      }
      if (!content.every(contentField => typeof contentField.value === 'string')) {
        throw new Error('Expected each `content` entry to contain a `value` string');
      }
      this.content = content;
    }
  }

  /**
   * Add content
   */
  addContent(content) {
    if (this._checkProperty('content', content, [this._createTypeCheck('object')])) {
      this.content.push(content);
    }
  }

  /**
   * Add text content
   */
  addTextContent(text) {
    if (this._checkProperty('text', text, [this._checkUndefined, this._createTypeCheck('string')])) {
      this.addContent({
        value: text,
        type: 'text/plain',
      });
    }
  }

  /**
   * Add HTML content
   */
  addHtmlContent(html) {
    if (this._checkProperty('html', html, [this._checkUndefined, this._createTypeCheck('string')])) {
      this.addContent({
        value: html,
        type: 'text/html',
      });
    }
  }

  /**
   * Set attachments
   */
  setAttachments(attachments) {
    if (this._doArrayCheck('attachments', attachments)) {
      if (!attachments.every(attachment => typeof attachment.content === 'string')) {
        throw new Error('Expected each attachment to contain a `content` string');
      }
      if (!attachments.every(attachment => typeof attachment.filename === 'string')) {
        throw new Error('Expected each attachment to contain a `filename` string');
      }
      if (!attachments.every(attachment => !attachment.type || typeof attachment.type === 'string')) {
        throw new Error('Expected the attachment\'s `type` field to be a string');
      }
      if (!attachments.every(attachment => !attachment.disposition || typeof attachment.disposition === 'string')) {
        throw new Error('Expected the attachment\'s `disposition` field to be a string');
      }
      this.attachments = attachments;
    }
  }

  /**
   * Add attachment
   */
  addAttachment(attachment) {
    if (this._checkProperty('attachment', attachment, [this._checkUndefined, this._createTypeCheck('object')])) {
      this.attachments.push(attachment);
    }
  }

  /**
   * Set categories
   */
  setCategories(categories) {
    let allElementsAreStrings = (propertyName, value) => {
      if (!Array.isArray(value) || !value.every(item => typeof item === 'string')) {
        throw new Error('Array of strings expected for `' + propertyName + '`');
      }
    };

    if (typeof categories === 'string') {
      categories = [categories];
    }

    if (this._checkProperty('categories', categories, [this._checkUndefined, allElementsAreStrings])) {
      this.categories = categories;
    }
  }

  /**
   * Add category
   */
  addCategory(category) {
    if (this._checkProperty('category', category, [this._createTypeCheck('string')])) {
      this.categories.push(category);
    }
  }

  /**
   * Set headers
   */
  setHeaders(headers) {
    this._setProperty('headers', headers, 'object');
  }

  /**
   * Add a header
   */
  addHeader(key, value) {
    if (this._checkProperty('key', key, [this._createTypeCheck('string')])
      && this._checkProperty('value', value, [this._createTypeCheck('string')])) {
      this.headers[key] = value;
    }
  }

  /**
   * Set sections
   */
  setSections(sections) {
    this._setProperty('sections', sections, 'object');
  }

  /**
   * Set custom args
   */
  setCustomArgs(customArgs) {
    this._setProperty('customArgs', customArgs, 'object');
  }

  /**
   * Set tracking settings
   */
  setTrackingSettings(settings) {
    if (typeof settings === 'undefined') {
      return;
    }
    validateTrackingSettings(settings);
    this.trackingSettings = settings;
  }

  /**
   * Set mail settings
   */
  setMailSettings(settings) {
    if (typeof settings === 'undefined') {
      return;
    }
    validateMailSettings(settings);
    this.mailSettings = settings;
  }

  /**
   * Set hide warnings
   */
  setHideWarnings(hide) {
    if (typeof hide === 'undefined') {
      return;
    }
    if (typeof hide !== 'boolean') {
      throw new Error('Boolean expected for `hideWarnings`');
    }
    this.hideWarnings = hide;
  }

  /**
   * To JSON
   */
  toJSON() {

    //Extract properties from self
    const {
      from, replyTo, sendAt, subject, content, templateId,
      personalizations, attachments, ipPoolName, batchId, asm,
      sections, headers, categories, customArgs, mailSettings,
      trackingSettings,
    } = this;

    //Initialize with mandatory values
    const json = {
      from, subject,
      personalizations: arrayToJSON(personalizations),
    };

    //Array properties
    if (Array.isArray(attachments) && attachments.length > 0) {
      json.attachments = arrayToJSON(attachments);
    }
    if (Array.isArray(categories) && categories.length > 0) {
      json.categories = categories.filter(cat => cat !== '');
    }
    if (Array.isArray(content) && content.length > 0) {
      json.content = arrayToJSON(content);
    }

    //Object properties
    if (Object.keys(headers).length > 0) {
      json.headers = headers;
    }
    if (Object.keys(mailSettings).length > 0) {
      json.mailSettings = mailSettings;
    }
    if (Object.keys(trackingSettings).length > 0) {
      json.trackingSettings = trackingSettings;
    }
    if (Object.keys(customArgs).length > 0) {
      json.customArgs = customArgs;
    }
    if (Object.keys(sections).length > 0) {
      json.sections = sections;
    }
    if (Object.keys(asm).length > 0) {
      json.asm = asm;
    }

    //Simple properties
    if (typeof replyTo !== 'undefined') {
      json.replyTo = replyTo;
    }
    if (typeof sendAt !== 'undefined') {
      json.sendAt = sendAt;
    }
    if (typeof batchId !== 'undefined') {
      json.batchId = batchId;
    }
    if (typeof templateId !== 'undefined') {
      json.templateId = templateId;
    }
    if (typeof ipPoolName !== 'undefined') {
      json.ipPoolName = ipPoolName;
    }

    //Return as snake cased object
    return toSnakeCase(json, ['substitutions', 'dynamicTemplateData', 'customArgs', 'headers', 'sections']);
  }

  /**************************************************************************
   * Static helpers
   ***/

  /**
   * Create a Mail instance from given data
   */
  static create(data) {

    //Array?
    if (Array.isArray(data)) {
      return data
        .filter(item => !!item)
        .map(item => this.create(item));
    }

    //Already instance of Mail class?
    if (data instanceof Mail) {
      return data;
    }

    //Create instance
    return new Mail(data);
  }

  /**************************************************************************
   * helpers for property-setting checks
   ***/

  /**
   * Perform a set of checks on the new property value. Returns true if all
   * checks complete successfully without throwing errors or returning true.
   */
  _checkProperty(propertyName, value, checks) {
    return !checks.some((e) => e(propertyName, value));
  }

  /**
   * Set a property with normal undefined and type-checks
   */
  _setProperty(propertyName, value, propertyType) {
    let propertyChecksPassed = this._checkProperty(
      propertyName,
      value,
      [this._checkUndefined, this._createTypeCheck(propertyType)]);

    if (propertyChecksPassed) {
      this[propertyName] = value;
    }

    return propertyChecksPassed;
  }

  /**
   * Fail if the value is undefined.
   */
  _checkUndefined(propertyName, value) {
    return typeof value === 'undefined';
  }

  /**
   * Create and return a function that checks for a given type
   */
  _createTypeCheck(propertyType) {
    return (propertyName, value) => {
      if (typeof value !== propertyType) {
        throw new Error(propertyType + ' expected for `' + propertyName + '`');
      }
    };
  }

  /**
   * Create a check out of a callback. If the callback
   * returns false, the check will throw an error.
   */
  _createCheckThatThrows(check, errorString) {
    return (propertyName, value) => {
      if (!check(value)) {
        throw new Error(errorString);
      }
    };
  }

  /**
   * Set an array property after checking that the new value is an
   * array.
   */
  _setArrayProperty(propertyName, value) {
    if (this._doArrayCheck(propertyName, value)) {
      this[propertyName] = value;
    }
  }

  /**
   * Check that a value isn't undefined and is an array.
   */
  _doArrayCheck(propertyName, value) {
    return this._checkProperty(
      propertyName,
      value,
      [this._checkUndefined, this._createCheckThatThrows(Array.isArray, 'Array expected for`' + propertyName + '`')]);
  }
}

//Export class
module.exports = Mail;
