/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import * as vscode from 'vscode';

class InputFlowAction {
	static back = new InputFlowAction();
	static cancel = new InputFlowAction();
	static resume = new InputFlowAction();
}

export type InputStep = (input: MultiStepInput) => Thenable<InputStep | void>;

interface QuickPickParameters<T extends vscode.QuickPickItem> {
	title: string | undefined;
	step: number;
	totalSteps: number;
	items: T[];
	placeholder: string;
	canSelectMany?: boolean;
	selectedItems?: readonly T[];
	buttons?: vscode.QuickInputButton[];
	shouldResume?: () => Thenable<boolean>;
}

interface InputBoxParameters {
	title: string | undefined;
	step: number;
	totalSteps: number;
	value: string;
	prompt: string;
	validate: (value: string) => Promise<string | undefined>;
	password?: boolean;
	buttons?: vscode.QuickInputButton[];
	shouldResume?: () => Thenable<boolean>;
}

export class MultiStepInput {

	static async run(start: InputStep) {
		const input = new MultiStepInput();
		return input.stepThrough(start);
	}

	private current?: vscode.QuickInput;
	private steps: InputStep[] = [];

	private async stepThrough(start: InputStep) {
		let step: InputStep | void = start;
		while (step) {
			this.steps.push(step);
			if (this.current) {
				this.current.enabled = false;
				this.current.busy = true;
			}
			try {
				step = await step(this);
			} catch (err) {
				if (err === InputFlowAction.back) {
					this.steps.pop();
					step = this.steps.pop();
				} else if (err === InputFlowAction.resume) {
					step = this.steps.pop();
				} else if (err === InputFlowAction.cancel) {
					step = undefined;
				} else {
					throw err;
				}
			}
		}
		if (this.current) {
			this.current.dispose();
		}
	}

	async showQuickPick<T extends vscode.QuickPickItem, P extends QuickPickParameters<T>>({ title, step, totalSteps, items, selectedItems, placeholder, canSelectMany, buttons, shouldResume }: P) {
		const disposables: vscode.Disposable[] = [];
		try {
			return await new Promise<readonly T[] | (P extends { buttons: (infer I)[] } ? I : never)>((resolve, reject) => {
				const input = vscode.window.createQuickPick<T>();
				input.title = title;
				input.step = step;
				input.totalSteps = totalSteps;
				input.placeholder = placeholder;
				input.items = items;
				if (canSelectMany) {
					input.canSelectMany = canSelectMany;
				}
				if (selectedItems) {
					input.selectedItems = selectedItems;
				}
				input.buttons = [
					...(this.steps.length > 1 ? [vscode.QuickInputButtons.Back] : []),
					...(buttons || [])
				];
				input.ignoreFocusOut = true;
				disposables.push(
					input.onDidTriggerButton(item => {
						if (item === vscode.QuickInputButtons.Back) {
							reject(InputFlowAction.back);
						} else {
							resolve(<any>item);
						}
					}),
					input.onDidAccept(() => {
						resolve(input.selectedItems);
					}),
					input.onDidHide(() => {
						(async () => {
							reject(shouldResume && await shouldResume() ? InputFlowAction.resume : InputFlowAction.cancel);
						})()
							.catch(reject);
					})
				);
				if (this.current) {
					this.current.dispose();
				}
				this.current = input;
				this.current.show();
			});
		} finally {
			disposables.forEach(d => d.dispose());
		}
	}

	async showInputBox<P extends InputBoxParameters>({ title, step, totalSteps, value, prompt, validate, password, buttons, shouldResume }: P) {
		const disposables: vscode.Disposable[] = [];
		try {
			return await new Promise<string | (P extends { buttons: (infer I)[] } ? I : never)>((resolve, reject) => {
				const input = vscode.window.createInputBox();
				input.title = title;
				input.step = step;
				input.totalSteps = totalSteps;
				input.value = value || '';
				input.prompt = prompt;
				if (password) {
					input.password = password;
				}
				input.buttons = [
					...(this.steps.length > 1 ? [vscode.QuickInputButtons.Back] : []),
					...(buttons || [])
				];
				input.ignoreFocusOut = true;
				// let validating = validate('');
				disposables.push(
					input.onDidTriggerButton(item => {
						if (item === vscode.QuickInputButtons.Back) {
							reject(InputFlowAction.back);
						} else {
							resolve(<any>item);
						}
					}),
					input.onDidAccept(async () => {
						const value = input.value;
						input.enabled = false;
						input.busy = true;
						const validationMessage = await validate(value);
						if (validationMessage) {
							input.validationMessage = validationMessage;
						} else {
							resolve(value);
						}
						input.enabled = true;
						input.busy = false;
					}),
					input.onDidHide(() => {
						(async () => {
							reject(shouldResume && await shouldResume() ? InputFlowAction.resume : InputFlowAction.cancel);
						})()
							.catch(reject);
					})
				);
				if (this.current) {
					this.current.dispose();
				}
				this.current = input;
				this.current.show();
			});
		} finally {
			disposables.forEach(d => d.dispose());
		}
	}
}