let deprecationHandler: ElectronInternal.DeprecationHandler | null = null;

function warnOnce (oldName: string, newName?: string) {
  let warned = false;
  const msg = newName
    ? `'${oldName}' is deprecated and will be removed. Please use '${newName}' instead.`
    : `'${oldName}' is deprecated and will be removed.`;
  return () => {
    if (!warned && !process.noDeprecation) {
      warned = true;
      deprecate.log(msg);
    }
  };
}

const deprecate: ElectronInternal.DeprecationUtil = {
  warnOnce,
  setHandler: (handler) => { deprecationHandler = handler; },
  getHandler: () => deprecationHandler,
  warn: (oldName, newName) => {
    if (!process.noDeprecation) {
      deprecate.log(`'${oldName}' is deprecated. Use '${newName}' instead.`);
    }
  },
  log: (message) => {
    if (typeof deprecationHandler === 'function') {
      deprecationHandler(message);
    } else if (process.throwDeprecation) {
      throw new Error(message);
    } else if (process.traceDeprecation) {
      return console.trace(message);
    } else {
      return console.warn(`(electron) ${message}`);
    }
  },

  // remove a function with no replacement
  removeFunction: (fn, removedName) => {
    if (!fn) { throw Error(`'${removedName} function' is invalid or does not exist.`); }

    // wrap the deprecated function to warn user
    const warn = warnOnce(`${fn.name} function`);
    return function (this: any) {
      warn();
      fn.apply(this, arguments);
    };
  },

  // change the name of a function
  renameFunction: (fn, newName) => {
    const warn = warnOnce(`${fn.name} function`, `${newName} function`);
    return function (this: any) {
      warn();
      return fn.apply(this, arguments);
    };
  },

  moveAPI: (fn: Function, oldUsage: string, newUsage: string) => {
    const warn = warnOnce(oldUsage, newUsage);
    return function (this: any) {
      warn();
      return fn.apply(this, arguments);
    };
  },

  // change the name of an event
  event: (emitter, oldName, newName) => {
    const warn = newName.startsWith('-') /* internal event */
      ? warnOnce(`${oldName} event`)
      : warnOnce(`${oldName} event`, `${newName} event`);
    return emitter.on(newName, function (this: NodeJS.EventEmitter, ...args) {
      if (this.listenerCount(oldName) !== 0) {
        warn();
        this.emit(oldName, ...args);
      }
    });
  },

  // deprecate a getter/setter function pair in favor of a property
  fnToProperty: (prototype: any, prop: string, getter: string, setter?: string) => {
    const withWarnOnce = function (obj: any, key: any, oldName: string, newName: string) {
      const warn = warnOnce(oldName, newName);
      const method = obj[key];
      return function (this: any, ...args: any) {
        warn();
        return method.apply(this, args);
      };
    };

    prototype[getter.substr(1)] = withWarnOnce(prototype, getter, `${getter.substr(1)} function`, `${prop} property`);
    if (setter) {
      prototype[setter.substr(1)] = withWarnOnce(prototype, setter, `${setter.substr(1)} function`, `${prop} property`);
    }
  },

  // remove a property with no replacement
  removeProperty: (o, removedName, onlyForValues) => {
    // if the property's already been removed, warn about it
    const info = Object.getOwnPropertyDescriptor((o as any).__proto__, removedName) // eslint-disable-line
    if (!info) {
      deprecate.log(`Unable to remove property '${removedName}' from an object that lacks it.`);
      return o;
    }
    if (!info.get || !info.set) {
      deprecate.log(`Unable to remove property '${removedName}' from an object does not have a getter / setter`);
      return o;
    }

    // wrap the deprecated property in an accessor to warn
    const warn = warnOnce(removedName);
    return Object.defineProperty(o, removedName, {
      configurable: true,
      get: () => {
        warn();
        return info.get!.call(o);
      },
      set: newVal => {
        if (!onlyForValues || onlyForValues.includes(newVal)) {
          warn();
        }
        return info.set!.call(o, newVal);
      }
    });
  },

  // change the name of a property
  renameProperty: (o, oldName, newName) => {
    const warn = warnOnce(oldName, newName);

    // if the new property isn't there yet,
    // inject it and warn about it
    if ((oldName in o) && !(newName in o)) {
      warn();
      o[newName] = (o as any)[oldName];
    }

    // wrap the deprecated property in an accessor to warn
    // and redirect to the new property
    return Object.defineProperty(o, oldName, {
      get: () => {
        warn();
        return o[newName];
      },
      set: value => {
        warn();
        o[newName] = value;
      }
    });
  }
};

export default deprecate;