/*
 * Copyright (c) 2018 Red Hat, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Red Hat, Inc. - initial API and implementation
 *
 * SPDX-License-Identifier: EPL-1.0
 */

import URI from '@theia/core/lib/common/uri';
import { UserStorageUri } from '@theia/userstorage/lib/browser/';
import { injectable, inject } from 'inversify';
import { Disposable, DisposableCollection, Resource, ResourceProvider, ILogger, Emitter, Event } from '@theia/core/lib/common';
import { FrontendApplicationContribution, FrontendApplication } from '@theia/core/lib/browser';
import * as jsoncparser from 'jsonc-parser';
import { ParseError } from 'jsonc-parser';
import { Properties } from '../common/github-model';

export const propertiesUri: URI = new URI('github.json').withScheme(UserStorageUri.SCHEME);

export const defaultProperties: Properties = {
  credentials: {
    type: 'token',
    token: 'token_value'
  }
};

@injectable()
export class GitHubProperties implements Disposable, FrontendApplicationContribution {
  protected readonly toDispose = new DisposableCollection();
  protected propertiesFile: Resource | undefined;
  protected properties: Properties | undefined;
  protected readonly onPropertiesChangeEmitter = new Emitter<Properties | undefined>();

  constructor(
    @inject(ResourceProvider) protected readonly resourceProvider: ResourceProvider,
    @inject(ILogger) protected readonly logger: ILogger
  ) { }

  dispose(): void {
    this.toDispose.dispose();
  }

  onStart(app: FrontendApplication): void {
    this.resourceProvider(propertiesUri).then(resource => {
      this.propertiesFile = resource;
      this.toDispose.push(this.propertiesFile);
      if (this.propertiesFile.onDidChangeContents) {
        this.propertiesFile.onDidChangeContents(() => {
          this.onDidConfigurationChange();
        });
      }

      resource.readContents().then(content => {
        if (content) {
          this.parseConfiguration(content);
        } else {
          if (resource.saveContents) {
            resource.saveContents(JSON.stringify(defaultProperties)).then(() => {
              this.parseConfiguration(JSON.stringify(defaultProperties));
            });
          }
        }
      });
    }).catch(error => {
      this.propertiesFile = undefined;
    });
  }

  getProperties(): Properties | undefined {
    return this.properties;
  }

  protected onDidConfigurationChange(): void {
    if (this.propertiesFile) {
      this.propertiesFile.readContents().then(content => {
        this.parseConfiguration(content);
      });
    }
  }

  protected parseConfiguration(content: string) {
    const strippedContent = jsoncparser.stripComments(content);
    const errors: ParseError[] = [];
    const configuration = jsoncparser.parse(strippedContent, errors);
    if (errors.length) {
      for (const error of errors) {
        this.logger.error('JSON parsing error: ', error);
      }
    }
    if (configuration) {
      this.setConfiguration(configuration);
    }
  }

  protected setConfiguration(configuration: any) {
    this.properties = configuration as Properties;

    this.fireGitHubConfigurationChange();
  }

  get onPropertiesChange(): Event<Properties | undefined> {
    return this.onPropertiesChangeEmitter.event;
  }

  protected fireGitHubConfigurationChange(): void {
    this.onPropertiesChangeEmitter.fire(this.properties);
  }
}