// *****************************************************************************
// Copyright (C) 2019 Red Hat, Inc. and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0.
//
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License v. 2.0 are satisfied: GNU General Public License, version 2
// with the GNU Classpath Exception which is available at
// https://www.gnu.org/software/classpath/license.html.
//
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
// *****************************************************************************

import { Disposable, DisposableCollection, Emitter } from '@theia/core/lib/common';
import URI from '@theia/core/lib/common/uri';
import { ScmInput, ScmInputOptions } from './scm-input';
import { ScmProvider } from './scm-provider';

export interface ScmProviderOptions {
    input?: ScmInputOptions;
    parentRootUri?: string;
}

export class ScmRepository implements Disposable {

    protected readonly onDidChangeEmitter = new Emitter<void>();
    readonly onDidChange = this.onDidChangeEmitter.event;
    protected fireDidChange(): void {
        this.onDidChangeEmitter.fire(undefined);
    }

    protected readonly toDispose = new DisposableCollection(this.onDidChangeEmitter);

    readonly input: ScmInput;

    get parentRootUri(): string | undefined {
        return this.options.parentRootUri;
    }

    constructor(
        readonly provider: ScmProvider,
        protected readonly options: ScmProviderOptions = {}
    ) {
        this.toDispose.pushAll([
            this.provider,
            this.input = new ScmInput(options.input),
            this.input.onDidChange(() => this.fireDidChange())
        ]);
    }

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

    /**
     * Build a URI that addresses the given file at a specific revision in this repository.
     *
     * The result reuses the workspace path of {@link fileUri} but switches the scheme to the
     * provider id and encodes `{ path, ref }` in the query, which is the contract resource
     * resolvers (e.g. the Git extension) expect to retrieve content at a revision.
     *
     * @param fileUri The workspace URI of the file (typically a `file:` URI).
     * @param ref The revision (commit, branch, tag). An empty string addresses the index.
     */
    toUriAtRef(fileUri: URI, ref: string): URI {
        const query = JSON.stringify({ path: fileUri.path.fsPath(), ref });
        return fileUri.withScheme(this.provider.id).withQuery(query);
    }

}