/** @flow weak */

import * as triggers        from "../triggers";
import * as Parse           from "parse/node";
import * as request         from "request";
import { logger }           from '../logger';

const DefaultHooksCollectionName = "_Hooks";

export class HooksController {
  _applicationId:string;
  _webhookKey:string;
  database: any;

  constructor(applicationId:string, databaseController, webhookKey) {
    this._applicationId = applicationId;
    this._webhookKey = webhookKey;
    this.database = databaseController;
  }

  load() {
    return this._getHooks().then(hooks => {
      hooks = hooks || [];
      hooks.forEach((hook) => {
        this.addHookToTriggers(hook);
      });
    });
  }

  getFunction(functionName) {
    return this._getHooks({ functionName: functionName }, 1).then(results => results[0]);
  }

  getFunctions() {
    return this._getHooks({ functionName: { $exists: true } });
  }

  getTrigger(className, triggerName) {
    return this._getHooks({ className: className, triggerName: triggerName }, 1).then(results => results[0]);
  }

  getTriggers() {
    return this._getHooks({ className: { $exists: true }, triggerName: { $exists: true } });
  }

  deleteFunction(functionName) {
    triggers.removeFunction(functionName, this._applicationId);
    return this._removeHooks({ functionName: functionName });
  }

  deleteTrigger(className, triggerName) {
    triggers.removeTrigger(triggerName, className, this._applicationId);
    return this._removeHooks({ className: className, triggerName: triggerName });
  }

  _getHooks(query = {}) {
    return this.database.find(DefaultHooksCollectionName, query).then((results) => {
      return results.map((result) => {
        delete result.objectId;
        return result;
      });
    });
  }

  _removeHooks(query) {
    return this.database.destroy(DefaultHooksCollectionName, query).then(() => {
      return Promise.resolve({});
    });
  }

  saveHook(hook) {
    var query;
    if (hook.functionName && hook.url) {
      query = { functionName: hook.functionName }
    } else if (hook.triggerName && hook.className && hook.url) {
      query = { className: hook.className, triggerName: hook.triggerName }
    } else {
      throw new Parse.Error(143, "invalid hook declaration");
    }
    return this.database.update(DefaultHooksCollectionName, query, hook, {upsert: true}).then(() => {
      return Promise.resolve(hook);
    })
  }

  addHookToTriggers(hook) {
    var wrappedFunction = wrapToHTTPRequest(hook, this._webhookKey);
    wrappedFunction.url = hook.url;
    if (hook.className) {
      triggers.addTrigger(hook.triggerName, hook.className, wrappedFunction, this._applicationId)
    } else {
      triggers.addFunction(hook.functionName, wrappedFunction, null, this._applicationId);
    }
  }

  addHook(hook) {
    this.addHookToTriggers(hook);
    return this.saveHook(hook);
  }

  createOrUpdateHook(aHook) {
    var hook;
    if (aHook && aHook.functionName && aHook.url) {
      hook = {};
      hook.functionName = aHook.functionName;
      hook.url = aHook.url;
    } else if (aHook && aHook.className && aHook.url && aHook.triggerName && triggers.Types[aHook.triggerName]) {
      hook = {};
      hook.className = aHook.className;
      hook.url = aHook.url;
      hook.triggerName = aHook.triggerName;

    } else {
      throw new Parse.Error(143, "invalid hook declaration");
    }

    return this.addHook(hook);
  }

  createHook(aHook) {
    if (aHook.functionName) {
      return this.getFunction(aHook.functionName).then((result) => {
        if (result) {
          throw new Parse.Error(143, `function name: ${aHook.functionName} already exits`);
        } else {
          return this.createOrUpdateHook(aHook);
        }
      });
    } else if (aHook.className && aHook.triggerName) {
      return this.getTrigger(aHook.className, aHook.triggerName).then((result) => {
        if (result) {
          throw new Parse.Error(143, `class ${aHook.className} already has trigger ${aHook.triggerName}`);
        }
        return this.createOrUpdateHook(aHook);
      });
    }

    throw new Parse.Error(143, "invalid hook declaration");
  }

  updateHook(aHook) {
    if (aHook.functionName) {
      return this.getFunction(aHook.functionName).then((result) => {
        if (result) {
          return this.createOrUpdateHook(aHook);
        }
        throw new Parse.Error(143, `no function named: ${aHook.functionName} is defined`);
      });
    } else if (aHook.className && aHook.triggerName) {
      return this.getTrigger(aHook.className, aHook.triggerName).then((result) => {
        if (result) {
          return this.createOrUpdateHook(aHook);
        }
        throw new Parse.Error(143, `class ${aHook.className} does not exist`);
      });
    }
    throw new Parse.Error(143, "invalid hook declaration");
  }
}

function wrapToHTTPRequest(hook, key) {
  return (req, res) => {
    const jsonBody = {};
    for (var i in req) {
      jsonBody[i] = req[i];
    }
    if (req.object) {
      jsonBody.object = req.object.toJSON();
      jsonBody.object.className = req.object.className;
    }
    if (req.original) {
      jsonBody.original = req.original.toJSON();
      jsonBody.original.className = req.original.className;
    }
    const jsonRequest: any = {
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(jsonBody)
    };

    if (key) {
      jsonRequest.headers['X-Parse-Webhook-Key'] = key;
    } else {
      logger.warn('Making outgoing webhook request without webhookKey being set!');
    }

    request.post(hook.url, jsonRequest, function (err, httpResponse, body) {
      var result;
      if (body) {
        if (typeof body === "string") {
          try {
            body = JSON.parse(body);
          } catch (e) {
            err = { error: "Malformed response", code: -1 };
          }
        }
        if (!err) {
          result = body.success;
          err = body.error;
        }
      }

      if (err) {
        return res.error(err);
      } else if (hook.triggerName === 'beforeSave') {
        if (typeof result === 'object') {
          delete result.createdAt;
          delete result.updatedAt;
        }
        return res.success({object: result});
      } else {
        return res.success(result);
      }
    });
  }
}

export default HooksController;