/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
'use strict';

import { TPromise } from 'vs/base/common/winjs.base';
import Event, { Emitter, once } from 'vs/base/common/event';
import * as objects from 'vs/base/common/objects';
import types = require('vs/base/common/types');
import URI from 'vs/base/common/uri';
import { IDisposable, dispose } from 'vs/base/common/lifecycle';
import { IEditor, ICommonCodeEditor, IEditorViewState, IEditorOptions as ICodeEditorOptions, IModel } from 'vs/editor/common/editorCommon';
import { IEditorInput, IEditorModel, IEditorOptions, ITextEditorOptions, IBaseResourceInput, Position } from 'vs/platform/editor/common/editor';
import { IWorkspaceContextService } from 'vs/platform/workspace/common/workspace';
import { IEditorGroupService } from 'vs/workbench/services/group/common/groupService';
import { SyncDescriptor, AsyncDescriptor } from 'vs/platform/instantiation/common/descriptors';
import { IInstantiationService, IConstructorSignature0 } from 'vs/platform/instantiation/common/instantiation';

export enum ConfirmResult {
	SAVE,
	DONT_SAVE,
	CANCEL
}

export interface IEditorDescriptor {

	getId(): string;

	getName(): string;

	describes(obj: any): boolean;
}

export const Extensions = {
	Editors: 'workbench.contributions.editors'
};

/**
 * Text diff editor id.
 */
export const TEXT_DIFF_EDITOR_ID = 'workbench.editors.textDiffEditor';

/**
 * Binary diff editor id.
 */
export const BINARY_DIFF_EDITOR_ID = 'workbench.editors.binaryResourceDiffEditor';

export interface IEditorRegistry {

	/**
	 * Registers an editor to the platform for the given input type. The second parameter also supports an
	 * array of input classes to be passed in. If the more than one editor is registered for the same editor
	 * input, the input itself will be asked which editor it prefers if this method is provided. Otherwise
	 * the first editor in the list will be returned.
	 *
	 * @param editorInputDescriptor a constructor function that returns an instance of EditorInput for which the
	 * registered editor should be used for.
	 */
	registerEditor(descriptor: IEditorDescriptor, editorInputDescriptor: SyncDescriptor<EditorInput>): void;
	registerEditor(descriptor: IEditorDescriptor, editorInputDescriptor: SyncDescriptor<EditorInput>[]): void;

	/**
	 * Returns the editor descriptor for the given input or null if none.
	 */
	getEditor(input: EditorInput): IEditorDescriptor;

	/**
	 * Returns the editor descriptor for the given identifier or null if none.
	 */
	getEditorById(editorId: string): IEditorDescriptor;

	/**
	 * Returns an array of registered editors known to the platform.
	 */
	getEditors(): IEditorDescriptor[];

	/**
	 * Registers the default input to be used for files in the workbench.
	 *
	 * @param editorInputDescriptor a descriptor that resolves to an instance of EditorInput that
	 * should be used to handle file inputs.
	 */
	registerDefaultFileInput(editorInputDescriptor: AsyncDescriptor<IFileEditorInput>): void;

	/**
	 * Returns a descriptor of the default input to be used for files in the workbench.
	 *
	 * @return a descriptor that resolves to an instance of EditorInput that should be used to handle
	 * file inputs.
	 */
	getDefaultFileInput(): AsyncDescriptor<IFileEditorInput>;

	/**
	 * Registers a editor input factory for the given editor input to the registry. An editor input factory
	 * is capable of serializing and deserializing editor inputs from string data.
	 *
	 * @param editorInputId the identifier of the editor input
	 * @param factory the editor input factory for serialization/deserialization
	 */
	registerEditorInputFactory(editorInputId: string, ctor: IConstructorSignature0<IEditorInputFactory>): void;

	/**
	 * Returns the editor input factory for the given editor input.
	 *
	 * @param editorInputId the identifier of the editor input
	 */
	getEditorInputFactory(editorInputId: string): IEditorInputFactory;

	setInstantiationService(service: IInstantiationService): void;
}

export interface IEditorInputFactory {

	/**
	 * Returns a string representation of the provided editor input that contains enough information
	 * to deserialize back to the original editor input from the deserialize() method.
	 */
	serialize(editorInput: EditorInput): string;

	/**
	 * Returns an editor input from the provided serialized form of the editor input. This form matches
	 * the value returned from the serialize() method.
	 */
	deserialize(instantiationService: IInstantiationService, serializedEditorInput: string): EditorInput;
}

/**
 * Editor inputs are lightweight objects that can be passed to the workbench API to open inside the editor part.
 * Each editor input is mapped to an editor that is capable of opening it through the Platform facade.
 */
export abstract class EditorInput implements IEditorInput {
	private _onDispose: Emitter<void>;
	protected _onDidChangeDirty: Emitter<void>;
	protected _onDidChangeLabel: Emitter<void>;

	private disposed: boolean;

	constructor() {
		this._onDidChangeDirty = new Emitter<void>();
		this._onDidChangeLabel = new Emitter<void>();
		this._onDispose = new Emitter<void>();

		this.disposed = false;
	}

	/**
	 * Fired when the dirty state of this input changes.
	 */
	public get onDidChangeDirty(): Event<void> {
		return this._onDidChangeDirty.event;
	}

	/**
	 * Fired when the label this input changes.
	 */
	public get onDidChangeLabel(): Event<void> {
		return this._onDidChangeLabel.event;
	}

	/**
	 * Fired when the model gets disposed.
	 */
	public get onDispose(): Event<void> {
		return this._onDispose.event;
	}

	/**
	 * Returns the name of this input that can be shown to the user. Examples include showing the name of the input
	 * above the editor area when the input is shown.
	 */
	public getName(): string {
		return null;
	}

	/**
	 * Returns the description of this input that can be shown to the user. Examples include showing the description of
	 * the input above the editor area to the side of the name of the input.
	 *
	 * @param verbose controls if the description should be short or can contain additional details.
	 */
	public getDescription(verbose?: boolean): string {
		return null;
	}

	/**
	 * Returns the unique type identifier of this input.
	 */
	public abstract getTypeId(): string;

	/**
	 * Returns the preferred editor for this input. A list of candidate editors is passed in that whee registered
	 * for the input. This allows subclasses to decide late which editor to use for the input on a case by case basis.
	 */
	public getPreferredEditorId(candidates: string[]): string {
		if (candidates && candidates.length > 0) {
			return candidates[0];
		}

		return null;
	}

	/**
	 * Returns a descriptor suitable for telemetry events or null if none is available.
	 *
	 * Subclasses should extend if they can contribute.
	 */
	public getTelemetryDescriptor(): { [key: string]: any; } {
		return { typeId: this.getTypeId() };
	}

	/**
	 * Returns a type of EditorModel that represents the resolved input. Subclasses should
	 * override to provide a meaningful model. The optional second argument allows to specify
	 * if the EditorModel should be refreshed before returning it. Depending on the implementation
	 * this could mean to refresh the editor model contents with the version from disk.
	 */
	public abstract resolve(refresh?: boolean): TPromise<IEditorModel>;

	/**
	 * An editor that is dirty will be asked to be saved once it closes.
	 */
	public isDirty(): boolean {
		return false;
	}

	/**
	 * Subclasses should bring up a proper dialog for the user if the editor is dirty and return the result.
	 */
	public confirmSave(): ConfirmResult {
		return ConfirmResult.DONT_SAVE;
	}

	/**
	 * Saves the editor if it is dirty. Subclasses return a promise with a boolean indicating the success of the operation.
	 */
	public save(): TPromise<boolean> {
		return TPromise.as(true);
	}

	/**
	 * Reverts the editor if it is dirty. Subclasses return a promise with a boolean indicating the success of the operation.
	 */
	public revert(): TPromise<boolean> {
		return TPromise.as(true);
	}

	/**
	 * Called when this input is no longer opened in any editor. Subclasses can free resources as needed.
	 */
	public close(): void {
		this.dispose();
	}

	/**
	 * Subclasses can set this to false if it does not make sense to split the editor input.
	 */
	public supportsSplitEditor(): boolean {
		return true;
	}

	/**
	 * Returns true if this input is identical to the otherInput.
	 */
	public matches(otherInput: any): boolean {
		return this === otherInput;
	}

	/**
	 * Called when an editor input is no longer needed. Allows to free up any resources taken by
	 * resolving the editor input.
	 */
	public dispose(): void {
		this.disposed = true;
		this._onDispose.fire();

		this._onDidChangeDirty.dispose();
		this._onDidChangeLabel.dispose();
		this._onDispose.dispose();
	}

	/**
	 * Returns whether this input was disposed or not.
	 */
	public isDisposed(): boolean {
		return this.disposed;
	}
}

export enum EncodingMode {

	/**
	 * Instructs the encoding support to encode the current input with the provided encoding
	 */
	Encode,

	/**
	 * Instructs the encoding support to decode the current input with the provided encoding
	 */
	Decode
}

export interface IEncodingSupport {

	/**
	 * Gets the encoding of the input if known.
	 */
	getEncoding(): string;

	/**
	 * Sets the encoding for the input for saving.
	 */
	setEncoding(encoding: string, mode: EncodingMode): void;
}

/**
 * This is a tagging interface to declare an editor input being capable of dealing with files. It is only used in the editor registry
 * to register this kind of input to the platform.
 */
export interface IFileEditorInput extends IEditorInput, IEncodingSupport {

	/**
	 * Gets the absolute file resource URI this input is about.
	 */
	getResource(): URI;

	/**
	 * Sets the absolute file resource URI this input is about.
	 */
	setResource(resource: URI): void;

	/**
	 * Sets the preferred encodingt to use for this input.
	 */
	setPreferredEncoding(encoding: string): void;
}

/**
 * Side by side editor inputs that have a master and details side.
 */
export class SideBySideEditorInput extends EditorInput {

	public static ID: string = 'workbench.editorinputs.sidebysideEditorInput';

	private _toUnbind: IDisposable[];

	constructor(private name: string, private description: string, private _details: EditorInput, private _master: EditorInput) {
		super();
		this._toUnbind = [];
		this.registerListeners();
	}

	get master(): EditorInput {
		return this._master;
	}

	get details(): EditorInput {
		return this._details;
	}

	public isDirty(): boolean {
		return this.master.isDirty();
	}

	public confirmSave(): ConfirmResult {
		return this.master.confirmSave();
	}

	public save(): TPromise<boolean> {
		return this.master.save();
	}

	public revert(): TPromise<boolean> {
		return this.master.revert();
	}

	public getTelemetryDescriptor(): { [key: string]: any; } {
		const descriptor = this.master.getTelemetryDescriptor();
		return objects.assign(descriptor, super.getTelemetryDescriptor());
	}

	private registerListeners(): void {

		// When the details or master input gets disposed, dispose this diff editor input
		const onceDetailsDisposed = once(this.details.onDispose);
		this._toUnbind.push(onceDetailsDisposed(() => {
			if (!this.isDisposed()) {
				this.dispose();
			}
		}));

		const onceMasterDisposed = once(this.master.onDispose);
		this._toUnbind.push(onceMasterDisposed(() => {
			if (!this.isDisposed()) {
				this.dispose();
			}
		}));

		// Reemit some events from the master side to the outside
		this._toUnbind.push(this.master.onDidChangeDirty(() => this._onDidChangeDirty.fire()));
		this._toUnbind.push(this.master.onDidChangeLabel(() => this._onDidChangeLabel.fire()));
	}

	public get toUnbind() {
		return this._toUnbind;
	}

	public resolve(refresh?: boolean): TPromise<EditorModel> {
		return TPromise.as(null);
	}

	getTypeId(): string {
		return SideBySideEditorInput.ID;
	}

	public getName(): string {
		return this.name;
	}

	public getDescription(): string {
		return this.description;
	}

	public supportsSplitEditor(): boolean {
		return false;
	}

	public matches(otherInput: any): boolean {
		if (super.matches(otherInput) === true) {
			return true;
		}

		if (otherInput) {
			if (!(otherInput instanceof SideBySideEditorInput)) {
				return false;
			}

			const otherDiffInput = <SideBySideEditorInput>otherInput;
			return this.details.matches(otherDiffInput.details) && this.master.matches(otherDiffInput.master);
		}

		return false;
	}

	public dispose(): void {
		this._toUnbind = dispose(this._toUnbind);
		super.dispose();
	}
}

export interface ITextEditorModel extends IEditorModel {
	textEditorModel: IModel;
}

/**
 * The editor model is the heavyweight counterpart of editor input. Depending on the editor input, it
 * connects to the disk to retrieve content and may allow for saving it back or reverting it. Editor models
 * are typically cached for some while because they are expensive to construct.
 */
export class EditorModel implements IEditorModel {
	private _onDispose: Emitter<void>;

	constructor() {
		this._onDispose = new Emitter<void>();
	}

	/**
	 * Fired when the model gets disposed.
	 */
	public get onDispose(): Event<void> {
		return this._onDispose.event;
	}

	/**
	 * Causes this model to load returning a promise when loading is completed.
	 */
	public load(): TPromise<EditorModel> {
		return TPromise.as(this);
	}

	/**
	 * Returns whether this model was loaded or not.
	 */
	public isResolved(): boolean {
		return true;
	}

	/**
	 * Subclasses should implement to free resources that have been claimed through loading.
	 */
	public dispose(): void {
		this._onDispose.fire();
		this._onDispose.dispose();
	}
}

/**
 * The editor options is the base class of options that can be passed in when opening an editor.
 */
export class EditorOptions implements IEditorOptions {

	/**
	 * Helper to create EditorOptions inline.
	 */
	public static create(settings: IEditorOptions): EditorOptions {
		const options = new EditorOptions();
		options.preserveFocus = settings.preserveFocus;
		options.forceOpen = settings.forceOpen;
		options.revealIfVisible = settings.revealIfVisible;
		options.pinned = settings.pinned;
		options.index = settings.index;
		options.inactive = settings.inactive;

		return options;
	}

	/**
	 * Inherit all options from other EditorOptions instance.
	 */
	public mixin(other: IEditorOptions): void {
		if (other) {
			this.preserveFocus = other.preserveFocus;
			this.forceOpen = other.forceOpen;
			this.revealIfVisible = other.revealIfVisible;
			this.pinned = other.pinned;
			this.index = other.index;
			this.inactive = other.inactive;
		}
	}

	/**
	 * Tells the editor to not receive keyboard focus when the editor is being opened. By default,
	 * the editor will receive keyboard focus on open.
	 */
	public preserveFocus: boolean;

	/**
	 * Tells the editor to replace the editor input in the editor even if it is identical to the one
	 * already showing. By default, the editor will not replace the input if it is identical to the
	 * one showing.
	 */
	public forceOpen: boolean;

	/**
	 * Will reveal the editor if it is already opened and visible in any of the opened editor groups.
	 */
	public revealIfVisible: boolean;

	/**
	 * An editor that is pinned remains in the editor stack even when another editor is being opened.
	 * An editor that is not pinned will always get replaced by another editor that is not pinned.
	 */
	public pinned: boolean;

	/**
	 * The index in the document stack where to insert the editor into when opening.
	 */
	public index: number;

	/**
	 * An active editor that is opened will show its contents directly. Set to true to open an editor
	 * in the background.
	 */
	public inactive: boolean;
}

/**
 * Base Text Editor Options.
 */
export class TextEditorOptions extends EditorOptions {
	protected startLineNumber: number;
	protected startColumn: number;
	protected endLineNumber: number;
	protected endColumn: number;

	private revealInCenterIfOutsideViewport: boolean;
	private editorViewState: IEditorViewState;
	private editorOptions: ICodeEditorOptions;

	public static from(input: IBaseResourceInput): TextEditorOptions {
		let options: TextEditorOptions = null;
		if (input && input.options) {
			if (input.options.selection || input.options.forceOpen || input.options.revealIfVisible || input.options.preserveFocus || input.options.pinned || input.options.inactive || typeof input.options.index === 'number') {
				options = new TextEditorOptions();
			}

			if (input.options.selection) {
				const selection = input.options.selection;
				options.selection(selection.startLineNumber, selection.startColumn, selection.endLineNumber, selection.endColumn);
			}

			if (input.options.forceOpen) {
				options.forceOpen = true;
			}

			if (input.options.revealIfVisible) {
				options.revealIfVisible = true;
			}

			if (input.options.preserveFocus) {
				options.preserveFocus = true;
			}

			if (input.options.pinned) {
				options.pinned = true;
			}

			if (input.options.inactive) {
				options.inactive = true;
			}

			if (input.options.revealInCenterIfOutsideViewport) {
				options.revealInCenterIfOutsideViewport = true;
			}

			if (typeof input.options.index === 'number') {
				options.index = input.options.index;
			}
		}

		return options;
	}

	/**
	 * Helper to create TextEditorOptions inline.
	 */
	public static create(settings: ITextEditorOptions): TextEditorOptions {
		const options = new TextEditorOptions();
		options.preserveFocus = settings.preserveFocus;
		options.forceOpen = settings.forceOpen;
		options.revealIfVisible = settings.revealIfVisible;
		options.pinned = settings.pinned;
		options.index = settings.index;

		if (settings.selection) {
			options.startLineNumber = settings.selection.startLineNumber;
			options.startColumn = settings.selection.startColumn;
			options.endLineNumber = settings.selection.endLineNumber || settings.selection.startLineNumber;
			options.endColumn = settings.selection.endColumn || settings.selection.startColumn;
		}

		return options;
	}

	/**
	 * Returns if this options object has objects defined for the editor.
	 */
	public hasOptionsDefined(): boolean {
		return !!this.editorViewState || (!types.isUndefinedOrNull(this.startLineNumber) && !types.isUndefinedOrNull(this.startColumn));
	}

	/**
	 * Tells the editor to set show the given selection when the editor is being opened.
	 */
	public selection(startLineNumber: number, startColumn: number, endLineNumber: number = startLineNumber, endColumn: number = startColumn): EditorOptions {
		this.startLineNumber = startLineNumber;
		this.startColumn = startColumn;
		this.endLineNumber = endLineNumber;
		this.endColumn = endColumn;

		return this;
	}

	/**
	 * Sets the view state to be used when the editor is opening.
	 */
	public fromEditor(editor: IEditor): void {

		// View state
		this.editorViewState = editor.saveViewState();

		// Selected editor options
		const codeEditor = <ICommonCodeEditor>editor;
		if (typeof codeEditor.getConfiguration === 'function') {
			const config = codeEditor.getConfiguration();
			if (config && config.viewInfo && config.wrappingInfo) {
				this.editorOptions = Object.create(null);
				this.editorOptions.renderWhitespace = config.viewInfo.renderWhitespace;
				this.editorOptions.renderControlCharacters = config.viewInfo.renderControlCharacters;
				this.editorOptions.wrappingColumn = config.wrappingInfo.isViewportWrapping ? 0 : -1;
			}
		}
	}

	/**
	 * Apply the view state or selection to the given editor.
	 *
	 * @return if something was applied
	 */
	public apply(editor: IEditor): boolean {

		// Editor options
		if (this.editorOptions) {
			editor.updateOptions(this.editorOptions);
		}

		// View state
		return this.applyViewState(editor);
	}

	private applyViewState(editor: IEditor): boolean {
		let gotApplied = false;

		// First try viewstate
		if (this.editorViewState) {
			editor.restoreViewState(this.editorViewState);
			gotApplied = true;
		}

		// Otherwise check for selection
		else if (!types.isUndefinedOrNull(this.startLineNumber) && !types.isUndefinedOrNull(this.startColumn)) {

			// Select
			if (!types.isUndefinedOrNull(this.endLineNumber) && !types.isUndefinedOrNull(this.endColumn)) {
				const range = {
					startLineNumber: this.startLineNumber,
					startColumn: this.startColumn,
					endLineNumber: this.endLineNumber,
					endColumn: this.endColumn
				};
				editor.setSelection(range);
				if (this.revealInCenterIfOutsideViewport) {
					editor.revealRangeInCenterIfOutsideViewport(range);
				} else {
					editor.revealRangeInCenter(range);
				}
			}

			// Reveal
			else {
				const pos = {
					lineNumber: this.startLineNumber,
					column: this.startColumn
				};
				editor.setPosition(pos);
				if (this.revealInCenterIfOutsideViewport) {
					editor.revealPositionInCenterIfOutsideViewport(pos);
				} else {
					editor.revealPositionInCenter(pos);
				}
			}

			gotApplied = true;
		}

		return gotApplied;
	}
}

export interface ITextDiffEditorOptions extends ITextEditorOptions {

	/**
	 * Whether to auto reveal the first change when the text editor is opened or not. By default
	 * the first change will not be revealed.
	 */
	autoRevealFirstChange: boolean;
}

/**
 * Base Text Diff Editor Options.
 */
export class TextDiffEditorOptions extends TextEditorOptions {

	/**
	 * Helper to create TextDiffEditorOptions inline.
	 */
	public static create(settings: ITextDiffEditorOptions): TextDiffEditorOptions {
		const options = new TextDiffEditorOptions();

		options.autoRevealFirstChange = settings.autoRevealFirstChange;

		options.preserveFocus = settings.preserveFocus;
		options.forceOpen = settings.forceOpen;
		options.revealIfVisible = settings.revealIfVisible;
		options.pinned = settings.pinned;
		options.index = settings.index;

		if (settings.selection) {
			options.startLineNumber = settings.selection.startLineNumber;
			options.startColumn = settings.selection.startColumn;
			options.endLineNumber = settings.selection.endLineNumber || settings.selection.startLineNumber;
			options.endColumn = settings.selection.endColumn || settings.selection.startColumn;
		}

		return options;
	}

	/**
	 * Whether to auto reveal the first change when the text editor is opened or not. By default
	 * the first change will not be revealed.
	 */
	public autoRevealFirstChange: boolean;
}

/**
 * Helper to return all opened editors with resources not belonging to the currently opened workspace.
 */
export function getOutOfWorkspaceEditorResources(editorGroupService: IEditorGroupService, contextService: IWorkspaceContextService): URI[] {
	const resources: URI[] = [];

	editorGroupService.getStacksModel().groups.forEach(group => {
		const editors = group.getEditors();
		editors.forEach(editor => {
			const fileResource = toResource(editor, { supportSideBySide: true, filter: 'file' });
			if (fileResource && !contextService.isInsideWorkspace(fileResource)) {
				resources.push(fileResource);
			}
		});
	});

	return resources;
}

export interface IStacksModelChangeEvent {
	group: IEditorGroup;
	editor?: IEditorInput;
	structural?: boolean;
}

export interface IEditorStacksModel {

	onModelChanged: Event<IStacksModelChangeEvent>;
	onEditorClosed: Event<IGroupEvent>;

	groups: IEditorGroup[];
	activeGroup: IEditorGroup;
	isActive(group: IEditorGroup): boolean;

	getGroup(id: GroupIdentifier): IEditorGroup;

	positionOfGroup(group: IEditorGroup): Position;
	groupAt(position: Position): IEditorGroup;

	next(jumpGroups: boolean): IEditorIdentifier;
	previous(jumpGroups: boolean): IEditorIdentifier;

	isOpen(editor: IEditorInput): boolean;
	isOpen(resource: URI): boolean;

	toString(): string;
}

export interface IEditorGroup {

	id: GroupIdentifier;
	label: string;
	count: number;
	activeEditor: IEditorInput;
	previewEditor: IEditorInput;

	getEditor(index: number): IEditorInput;
	getEditor(resource: URI): IEditorInput;
	indexOf(editor: IEditorInput): number;

	contains(editor: IEditorInput): boolean;
	contains(resource: URI): boolean;

	getEditors(mru?: boolean): IEditorInput[];
	isActive(editor: IEditorInput): boolean;
	isPreview(editor: IEditorInput): boolean;
	isPinned(index: number): boolean;
	isPinned(editor: IEditorInput): boolean;
}

export interface IEditorIdentifier {
	group: IEditorGroup;
	editor: IEditorInput;
}

export interface IEditorContext extends IEditorIdentifier {
	event: any;
}

export interface IGroupEvent {
	editor: IEditorInput;
	pinned: boolean;
	index: number;
}

export type GroupIdentifier = number;

export const EditorOpenPositioning = {
	LEFT: 'left',
	RIGHT: 'right',
	FIRST: 'first',
	LAST: 'last'
};

export interface IWorkbenchEditorConfiguration {
	workbench: {
		editor: {
			showTabs: boolean;
			showTabCloseButton: boolean;
			showIcons: boolean;
			enablePreview: boolean;
			enablePreviewFromQuickOpen: boolean;
			openPositioning: 'left' | 'right' | 'first' | 'last';
		}
	};
}

export const ActiveEditorMovePositioning = {
	FIRST: 'first',
	LAST: 'last',
	LEFT: 'left',
	RIGHT: 'right',
	CENTER: 'center',
	POSITION: 'position',
};

export const ActiveEditorMovePositioningBy = {
	TAB: 'tab',
	GROUP: 'group'
};

export interface ActiveEditorMoveArguments {
	to?: string;
	by?: string;
	value?: number;
}

export const EditorCommands = {
	MoveActiveEditor: 'moveActiveEditor'
};

export interface IResourceOptions {
	supportSideBySide?: boolean;
	filter?: 'file' | 'untitled' | ['file', 'untitled'] | ['untitled', 'file'];
}

export function hasResource(editor: IEditorInput, options?: IResourceOptions): boolean {
	return !!toResource(editor, options);
}

export function toResource(editor: IEditorInput, options?: IResourceOptions): URI {
	if (!editor) {
		return null;
	}

	// Check for side by side if we are asked to
	if (options && options.supportSideBySide && editor instanceof SideBySideEditorInput) {
		editor = editor.master;
	}

	const resource = doGetEditorResource(editor);
	if (!options || !options.filter) {
		return resource; // return early if no filter is specified
	}

	if (!resource) {
		return null;
	}

	let includeFiles: boolean;
	let includeUntitled: boolean;
	if (Array.isArray(options.filter)) {
		includeFiles = (options.filter.indexOf('file') >= 0);
		includeUntitled = (options.filter.indexOf('untitled') >= 0);
	} else {
		includeFiles = (options.filter === 'file');
		includeUntitled = (options.filter === 'untitled');
	}

	if (includeFiles && resource.scheme === 'file') {
		return resource;
	}

	if (includeUntitled && resource.scheme === 'untitled') {
		return resource;
	}

	return null;
}

// TODO@Ben every editor should have an associated resource
function doGetEditorResource(editor: IEditorInput): URI {
	if (editor instanceof EditorInput && typeof (<any>editor).getResource === 'function') {
		const candidate = (<any>editor).getResource();
		if (candidate instanceof URI) {
			return candidate;
		}
	}

	return null;
}