/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the Source EULA. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import type * as vscode from 'vscode';
import { Emitter, Event } from 'vs/base/common/event';
import { IMainContext, MainContext, MainThreadAuthenticationShape, ExtHostAuthenticationShape } from 'vs/workbench/api/common/extHost.protocol';
import { Disposable } from 'vs/workbench/api/common/extHostTypes';
import { IExtensionDescription, ExtensionIdentifier } from 'vs/platform/extensions/common/extensions';

interface GetSessionsRequest {
	scopes: string;
	result: Promise<vscode.AuthenticationSession | undefined>;
}

interface ProviderWithMetadata {
	label: string;
	provider: vscode.AuthenticationProvider;
	options: vscode.AuthenticationProviderOptions;
}

export class ExtHostAuthentication implements ExtHostAuthenticationShape {
	private _proxy: MainThreadAuthenticationShape;
	private _authenticationProviders: Map<string, ProviderWithMetadata> = new Map<string, ProviderWithMetadata>();

	private _providers: vscode.AuthenticationProviderInformation[] = [];

	private _onDidChangeSessions = new Emitter<vscode.AuthenticationSessionsChangeEvent>();
	readonly onDidChangeSessions: Event<vscode.AuthenticationSessionsChangeEvent> = this._onDidChangeSessions.event;

	private _inFlightRequests = new Map<string, GetSessionsRequest[]>();

	constructor(mainContext: IMainContext) {
		this._proxy = mainContext.getProxy(MainContext.MainThreadAuthentication);
	}

	$setProviders(providers: vscode.AuthenticationProviderInformation[]): Promise<void> {
		this._providers = providers;
		return Promise.resolve();
	}

	async getSession(requestingExtension: IExtensionDescription, providerId: string, scopes: readonly string[], options: vscode.AuthenticationGetSessionOptions & ({ createIfNone: true } | { forceNewSession: true } | { forceNewSession: { detail: string } })): Promise<vscode.AuthenticationSession>;
	async getSession(requestingExtension: IExtensionDescription, providerId: string, scopes: readonly string[], options: vscode.AuthenticationGetSessionOptions & { forceNewSession: true }): Promise<vscode.AuthenticationSession>;
	async getSession(requestingExtension: IExtensionDescription, providerId: string, scopes: readonly string[], options: vscode.AuthenticationGetSessionOptions & { forceNewSession: { detail: string } }): Promise<vscode.AuthenticationSession>;
	async getSession(requestingExtension: IExtensionDescription, providerId: string, scopes: readonly string[], options: vscode.AuthenticationGetSessionOptions): Promise<vscode.AuthenticationSession | undefined>;
	async getSession(requestingExtension: IExtensionDescription, providerId: string, scopes: readonly string[], options: vscode.AuthenticationGetSessionOptions = {}): Promise<vscode.AuthenticationSession | undefined> {
		const extensionId = ExtensionIdentifier.toKey(requestingExtension.identifier);
		const inFlightRequests = this._inFlightRequests.get(extensionId) || [];
		const sortedScopes = [...scopes].sort().join(' ');
		let inFlightRequest: GetSessionsRequest | undefined = inFlightRequests.find(request => request.scopes === sortedScopes);

		if (inFlightRequest) {
			return inFlightRequest.result;
		} else {
			const session = this._getSession(requestingExtension, extensionId, providerId, scopes, options);
			inFlightRequest = {
				scopes: sortedScopes,
				result: session
			};

			inFlightRequests.push(inFlightRequest);
			this._inFlightRequests.set(extensionId, inFlightRequests);

			try {
				await session;
			} finally {
				const requestIndex = inFlightRequests.findIndex(request => request.scopes === sortedScopes);
				if (requestIndex > -1) {
					inFlightRequests.splice(requestIndex);
					this._inFlightRequests.set(extensionId, inFlightRequests);
				}
			}

			return session;
		}
	}

	private async _getSession(requestingExtension: IExtensionDescription, extensionId: string, providerId: string, scopes: readonly string[], options: vscode.AuthenticationGetSessionOptions = {}): Promise<vscode.AuthenticationSession | undefined> {
		await this._proxy.$ensureProvider(providerId);
		const extensionName = requestingExtension.displayName || requestingExtension.name;
		return this._proxy.$getSession(providerId, scopes, extensionId, extensionName, options);
	}

	async removeSession(providerId: string, sessionId: string): Promise<void> {
		const providerData = this._authenticationProviders.get(providerId);
		if (!providerData) {
			return this._proxy.$removeSession(providerId, sessionId);
		}

		return providerData.provider.removeSession(sessionId);
	}

	registerAuthenticationProvider(id: string, label: string, provider: vscode.AuthenticationProvider, options?: vscode.AuthenticationProviderOptions): vscode.Disposable {
		if (this._authenticationProviders.get(id)) {
			throw new Error(`An authentication provider with id '${id}' is already registered.`);
		}

		this._authenticationProviders.set(id, { label, provider, options: options ?? { supportsMultipleAccounts: false } });

		if (!this._providers.find(p => p.id === id)) {
			this._providers.push({
				id: id,
				label: label
			});
		}

		const listener = provider.onDidChangeSessions(e => {
			this._proxy.$sendDidChangeSessions(id, {
				added: e.added ?? [],
				changed: e.changed ?? [],
				removed: e.removed ?? []
			});
		});

		this._proxy.$registerAuthenticationProvider(id, label, options?.supportsMultipleAccounts ?? false);

		return new Disposable(() => {
			listener.dispose();
			this._authenticationProviders.delete(id);

			const i = this._providers.findIndex(p => p.id === id);
			if (i > -1) {
				this._providers.splice(i);
			}

			this._proxy.$unregisterAuthenticationProvider(id);
		});
	}

	$createSession(providerId: string, scopes: string[]): Promise<vscode.AuthenticationSession> {
		const providerData = this._authenticationProviders.get(providerId);
		if (providerData) {
			return Promise.resolve(providerData.provider.createSession(scopes));
		}

		throw new Error(`Unable to find authentication provider with handle: ${providerId}`);
	}

	$removeSession(providerId: string, sessionId: string): Promise<void> {
		const providerData = this._authenticationProviders.get(providerId);
		if (providerData) {
			return Promise.resolve(providerData.provider.removeSession(sessionId));
		}

		throw new Error(`Unable to find authentication provider with handle: ${providerId}`);
	}

	$getSessions(providerId: string, scopes?: string[]): Promise<ReadonlyArray<vscode.AuthenticationSession>> {
		const providerData = this._authenticationProviders.get(providerId);
		if (providerData) {
			return Promise.resolve(providerData.provider.getSessions(scopes));
		}

		throw new Error(`Unable to find authentication provider with handle: ${providerId}`);
	}

	$onDidChangeAuthenticationSessions(id: string, label: string) {
		this._onDidChangeSessions.fire({ provider: { id, label } });
		return Promise.resolve();
	}
}