awesome-cordova-plugins/src/@ionic-native/core/plugin.ts

import { get, getPlugin, getPromise, cordovaWarn, pluginWarn } from './util';
import { checkReady } from './bootstrap';
import { CordovaOptions } from './decorators';

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/fromEvent';

checkReady();

declare var window;
declare var Promise;


/**
 * Checks if plugin/cordova is available
 * @return {boolean | { error: string } }
 * @private
 */
export function checkAvailability(pluginRef: string, methodName?: string, pluginName?: string);
export function checkAvailability(pluginObj: any, methodName?: string, pluginName?: string);
export function checkAvailability(plugin: any, methodName?: string, pluginName?: string): boolean | { error: string } {

  let pluginRef, pluginInstance, pluginPackage;

  if (typeof plugin === 'string') {
    pluginRef = plugin;
  } else {
    pluginRef = plugin.constructor.getPluginRef();
    pluginName = plugin.constructor.getPluginName();
    pluginPackage = plugin.constructor.getPluginInstallName();
  }

  pluginInstance = getPlugin(pluginRef);

  if (!pluginInstance || (!!methodName && typeof pluginInstance[methodName] === 'undefined')) {
    if (!window.cordova) {
      cordovaWarn(pluginName, methodName);
      return {
        error: 'cordova_not_available'
      };
    }

    pluginWarn(pluginName, pluginPackage, methodName);
    return {
      error: 'plugin_not_installed'
    };
  }

  return true;
}

/**
 * Checks if _objectInstance exists and has the method/property
 * @private
 */
export function instanceAvailability(pluginObj: any, methodName?: string): boolean {
  return pluginObj._objectInstance && (!methodName || typeof pluginObj._objectInstance[methodName] !== 'undefined');
}

function setIndex(args: any[], opts: any = {}, resolve?: Function, reject?: Function): any {
  // ignore resolve and reject in case sync
  if (opts.sync) {
    return args;
  }

  // If the plugin method expects myMethod(success, err, options)
  if (opts.callbackOrder === 'reverse') {
    // Get those arguments in the order [resolve, reject, ...restOfArgs]
    args.unshift(reject);
    args.unshift(resolve);
  } else if (opts.callbackStyle === 'node') {
    args.push((err, result) => {
      if (err) {
        reject(err);
      } else {
        resolve(result);
      }
    });
  } else if (opts.callbackStyle === 'object' && opts.successName && opts.errorName) {
    let obj: any = {};
    obj[opts.successName] = resolve;
    obj[opts.errorName] = reject;
    args.push(obj);
  } else if (typeof opts.successIndex !== 'undefined' || typeof opts.errorIndex !== 'undefined') {
    const setSuccessIndex = () => {
      // If we've specified a success/error index
      if (opts.successIndex > args.length) {
        args[opts.successIndex] = resolve;
      } else {
        args.splice(opts.successIndex, 0, resolve);
      }
    };

    const setErrorIndex = () => {
      // We don't want that the reject cb gets spliced into the position of an optional argument that has not been defined and thus causing non expected behaviour.
      if (opts.errorIndex > args.length) {
        args[opts.errorIndex] = reject; // insert the reject fn at the correct specific index
      } else {
        args.splice(opts.errorIndex, 0, reject); // otherwise just splice it into the array
      }
    };

    if (opts.successIndex > opts.errorIndex) {
      setErrorIndex();
      setSuccessIndex();
    } else {
      setSuccessIndex();
      setErrorIndex();
    }


  } else {
    // Otherwise, let's tack them on to the end of the argument list
    // which is 90% of cases
    args.push(resolve);
    args.push(reject);
  }
  return args;
}

function callCordovaPlugin(pluginObj: any, methodName: string, args: any[], opts: any = {}, resolve?: Function, reject?: Function) {
  // Try to figure out where the success/error callbacks need to be bound
  // to our promise resolve/reject handlers.
  args = setIndex(args, opts, resolve, reject);

  const availabilityCheck = checkAvailability(pluginObj, methodName);

  if (availabilityCheck === true) {
    const pluginInstance = getPlugin(pluginObj.constructor.getPluginRef());
    return pluginInstance[methodName].apply(pluginInstance, args);
  } else {
    return availabilityCheck;
  }

}

function wrapPromise(pluginObj: any, methodName: string, args: any[], opts: any = {}) {
  let pluginResult, rej;
  const p = getPromise((resolve, reject) => {
    pluginResult = callCordovaPlugin(pluginObj, methodName, args, opts, resolve, reject);
    rej = reject;
  });
  // Angular throws an error on unhandled rejection, but in this case we have already printed
  // a warning that Cordova is undefined or the plugin is uninstalled, so there is no reason
  // to error
  if (pluginResult && pluginResult.error) {
    p.catch(() => { });
    rej(pluginResult.error);
  }
  return p;
}

function wrapOtherPromise(pluginObj: any, methodName: string, args: any[], opts: any = {}) {
  return getPromise((resolve, reject) => {
    const pluginResult = callCordovaPlugin(pluginObj, methodName, args, opts);
    if (pluginResult) {
      if (pluginResult.error) {
        reject(pluginResult.error);
      } else if (pluginResult.then) {
        pluginResult.then(resolve).catch(reject);
      }
    } else {
      reject({ error: 'unexpected_error' });
    }
  });
}

function wrapObservable(pluginObj: any, methodName: string, args: any[], opts: any = {}) {
  return new Observable(observer => {
    let pluginResult = callCordovaPlugin(pluginObj, methodName, args, opts, observer.next.bind(observer), observer.error.bind(observer));
    if (pluginResult && pluginResult.error) {
      observer.error(pluginResult.error);
      observer.complete();
    }
    return () => {
      try {
        if (opts.clearFunction) {
          if (opts.clearWithArgs) {
            return callCordovaPlugin(pluginObj, opts.clearFunction, args, opts, observer.next.bind(observer), observer.error.bind(observer));
          }
          return get(window, pluginObj.constructor.getPluginRef())[opts.clearFunction].call(pluginObj, pluginResult);
        }
      } catch (e) {
        console.warn('Unable to clear the previous observable watch for', pluginObj.constructor.getPluginName(), methodName);
        console.error(e);
      }
    };
  });
}

function callInstance(pluginObj: any, methodName: string, args: any[], opts: any = {}, resolve?: Function, reject?: Function) {

  args = setIndex(args, opts, resolve, reject);

  if (instanceAvailability(pluginObj, methodName)) {
    return pluginObj._objectInstance[methodName].apply(pluginObj._objectInstance, args);
  }

}

/**
 * Wrap the event with an observable
 * @private
 * @param event even name
 * @param element The element to attach the event listener to
 * @returns {Observable}
 */
export function wrapEventObservable(event: string, element: any = window): Observable<any> {
  return Observable.fromEvent(element, event);
}

/**
 * Certain plugins expect the user to override methods in the plugin. For example,
 * window.cordova.plugins.backgroundMode.onactivate = function() { ... }.
 *
 * Unfortunately, this is brittle and would be better wrapped as an Observable. overrideFunction
 * does just this.
 * @private
 */
export function overrideFunction(pluginObj: any, methodName: string, args: any[], opts: any = {}): Observable<any> {
  return new Observable(observer => {

    const availabilityCheck = checkAvailability(pluginObj, methodName);

    if (availabilityCheck === true) {
      const pluginInstance = getPlugin(pluginObj.constructor.getPluginRef());
      pluginInstance[methodName] = observer.next.bind(observer);
      return () => pluginInstance[methodName] = () => { };
    } else {
      observer.error(availabilityCheck);
      observer.complete();
    }

  });
}


/**
 * @private
 */
export const wrap = function(pluginObj: any, methodName: string, opts: CordovaOptions = {}) {
  return (...args) => {
    if (opts.sync) {
      // Sync doesn't wrap the plugin with a promise or observable, it returns the result as-is
      return callCordovaPlugin(pluginObj, methodName, args, opts);
    } else if (opts.observable) {
      return wrapObservable(pluginObj, methodName, args, opts);
    } else if (opts.eventObservable && opts.event) {
      return wrapEventObservable(opts.event, opts.element);
    } else if (opts.otherPromise) {
      return wrapOtherPromise(pluginObj, methodName, args, opts);
    } else {
      return wrapPromise(pluginObj, methodName, args, opts);
    }
  };
};

/**
 * @private
 */
export function wrapInstance(pluginObj: any, methodName: string, opts: any = {}) {
  return (...args) => {
    if (opts.sync) {

      return callInstance(pluginObj, methodName, args, opts);

    } else if (opts.observable) {

      return new Observable(observer => {
        let pluginResult = callInstance(pluginObj, methodName, args, opts, observer.next.bind(observer), observer.error.bind(observer));

        if (pluginResult && pluginResult.error) {
          observer.error(pluginResult.error);
          observer.complete();
        }

        return () => {
          try {
            if (opts.clearWithArgs) {
              return pluginObj._objectInstance[opts.clearFunction].apply(pluginObj._objectInstance, args);
            }
            return pluginObj._objectInstance[opts.clearFunction].call(pluginObj, pluginResult);
          } catch (e) {
            console.warn('Unable to clear the previous observable watch for', pluginObj.constructor.getPluginName(), methodName);
            console.error(e);
          }
        };
      });

    } else if (opts.otherPromise) {

      return getPromise((resolve, reject) => {
        let result = callInstance(pluginObj, methodName, args, opts, resolve, reject);
        if (result && !result.error) {
          result.then(resolve, reject);
        }
      });

    } else {

      let pluginResult, rej;
      const p = getPromise((resolve, reject) => {
        pluginResult = callInstance(pluginObj, methodName, args, opts, resolve, reject);
        rej = reject;
      });
      if (pluginResult && pluginResult.error) {
        p.catch(() => { });
        rej(pluginResult.error);
      }
      return p;

    }
  };
}