import yargs, { Argv } from 'yargs';
import * as clack from '@clack/prompts';
import { DummyWriteStream } from './write-stream';
import pino, {LogFn} from 'pino';
import * as util from 'util';

export interface Logger extends pino.BaseLogger {}

export interface CommandHandlerArgs {
	self: any;
	interactive: boolean;
	send: (message: number) => void;
	logger: Logger;
	args: any;
}

export type CommandHandler = (args: CommandHandlerArgs) => void | number | Promise<number> | Promise<void>;

export interface CommandArgs {
	aliases?: string[];
	command: string;
	parameters: string[];
	describe: string;
	handler: CommandHandler;
	interactiveMode?: boolean;
}

type PromptValueArgs = [Record<string, string>, ...never[]]
	| [string, string]
	| [[string, string], ...never[]]
	| [[string, string][], ...never[]];

export interface TestModeResult {
	exitCode?: number;
	stdout: DummyWriteStream;
	stderr: DummyWriteStream;
}

interface InteractiveModeOptions {
	option: string;
	alias: string;
	intro: string;
	cancelled: string;
	outro: string;
	describe: string;
}

export interface CliOptions {
	name: string;
	interactiveMode?: Partial<InteractiveModeOptions>;
	logger?: Logger | boolean;
}

export class Cli {
	private testMode = false;

	private promptValues = {} as Record<string, unknown>;

	private testModeResult: TestModeResult = {
		exitCode: undefined as number | undefined,
		stdout: new DummyWriteStream(),
		stderr: new DummyWriteStream(),
	};

	private readonly cli: Argv;

	constructor(private readonly options: CliOptions) {
		this.cli = yargs()
			.scriptName(options.name)
			.help()
			.fail(false)
			.strict(false);
	}

	private exit(code: number) {
		if (this.testMode) {
			this.testModeResult.exitCode = code;
			return;
		}
		process.exit(code);
	}

	private async prompt(messages: Record<string, string>, interactiveModeOptions: InteractiveModeOptions) {
		const {
			intro,
			cancelled,
			outro,
		} = interactiveModeOptions;
		const messagesEntries = Object.entries(messages);

		if (messagesEntries.length > 0) {
			clack.intro(intro);
			const values = await clack.group(
				Object.fromEntries(
					messagesEntries.map(([key, value]) => [key, () => clack.text({ message: value })])
				),
				{
					onCancel: () => {
						clack.cancel(cancelled);
						this.exit(1);
					}
				}
			);
			clack.outro(outro);
			return values;
		}

		return {};
	}

	private async generateCommandArgs(
		context: any,
		originalCommandArgs: Record<string, unknown>,
		interactive: boolean,
		interactiveModeOptions: InteractiveModeOptions,
	) {
		if (!interactive) {
			return originalCommandArgs;
		}

		// TODO properly filter attributes
		const clackGroup = context.optional
			.filter((optional: { cmd: string[] }) => {
				const {
					'$0': _$0,
					i: _i,
					interactive: _interactive,
					test: _test,
					_: __,
					...rest
				} = originalCommandArgs;

				return !Object.keys(rest).includes(optional.cmd[0]);
			})
			.reduce(
				(group: Record<string, string>, optional: { cmd: string[], describe: string }) => ({
					...group,
					[optional.cmd[0]]: optional.describe ?? optional.cmd[0],
				}),
				{} as Record<string, string>,
			);


		const promptedArgs = this.testMode
			? this.promptValues
			: await this.prompt(clackGroup, interactiveModeOptions);

		return {
			...originalCommandArgs,
			...promptedArgs,
		};
	}

	private buildHandler(handlerFn: Function, interactiveModeOptions: InteractiveModeOptions) {
		const thisCli = this;
		return async function handler(this: any, commandArgs: Record<string, unknown>) {
			const self = this;
			const { option, alias } = interactiveModeOptions;
			const interactiveLong = option in commandArgs ? Boolean(commandArgs.interactive) : false;
			const interactiveShort = alias in commandArgs ? Boolean(commandArgs.i) : false;
			const interactive = interactiveLong || interactiveShort;
			const buildArgs = await thisCli.generateCommandArgs(
				self,
				commandArgs,
				interactive,
				interactiveModeOptions,
			);

			const stdoutLogFn: LogFn = (...args: unknown[]) => {
				const stream = thisCli.testMode ? thisCli.testModeResult.stdout : process.stdout;
				const [arg0, arg1, ...etcArgs] = args;
				if (typeof arg0 === 'string' || typeof arg0 === 'number') {
					if (arg1) {
						if (etcArgs.length > 0) {
							stream.write(util.format(`${arg0}\n`, arg1, ...etcArgs));
						} else {
							stream.write(util.format(`${arg0}\n`, arg1));
						}
					} else {
						stream.write(util.format(`${arg0}\n`));
					}
				} else if (typeof arg0 === 'object' && (typeof arg1 === 'string' || typeof arg1 === 'number')) {
					if (etcArgs.length > 0) {
						stream.write(util.format(`${arg1}\n`, ...etcArgs));
					} else {
						stream.write(util.format(`${arg1}\n`));
					}
				}
			};

			const stderrLogFn: LogFn = (...args: unknown[]) => {
				const stream = thisCli.testMode ? thisCli.testModeResult.stderr : process.stderr;
				const [arg0, arg1, ...etcArgs] = args;
				if (typeof arg0 === 'string' || typeof arg0 === 'number') {
					if (arg1) {
						if (etcArgs.length > 0) {
							stream.write(util.format(`${arg0}\n`, arg1, ...etcArgs));
						} else {
							stream.write(util.format(`${arg0}\n`, arg1));
						}
					} else {
						stream.write(util.format(`${arg0}\n`));
					}
				} else if (typeof arg0 === 'object' && (typeof arg1 === 'string' || typeof arg1 === 'number')) {
					if (etcArgs.length > 0) {
						stream.write(util.format(`${arg1}\n`, ...etcArgs));
					} else {
						stream.write(util.format(`${arg1}\n`));
					}
				}
			};

			const loggerFn = thisCli.options.logger;
			const defaultLogger = {
				level: 'info',
				enabled: typeof loggerFn === 'boolean' ? loggerFn : true,
				debug: stdoutLogFn,
				info: stdoutLogFn,
				warn: stdoutLogFn,
				error: stderrLogFn,
				fatal: stderrLogFn,
				trace: stdoutLogFn,
				silent: () => {},
			} as Logger;
			const loggerBooleanFn = typeof loggerFn === 'boolean' && loggerFn ? defaultLogger : {
				level: 'silent',
				debug: () => {},
				info: () => {},
				warn: () => {},
				error: () => {},
				fatal: () => {},
				trace: () => {},
				silent: () => {},
			} as Logger;
			const logger = typeof loggerFn === 'undefined' ? defaultLogger : (typeof loggerFn === 'function' ? loggerFn : loggerBooleanFn);

			let exited = false;
			const returnCode = await handlerFn({
				self,
				interactive,
				logger,
				send: (code: number) => {
					exited = true;
					thisCli.exit(code);
				},
				args: buildArgs,
			});

			if (!exited) {
				thisCli.exit(returnCode ? returnCode : 0);
			}
		};
	}

	command({ parameters, command, interactiveMode = true, handler, ...args }: CommandArgs): Cli {
		// TODO type-safe declaration of positional/optional arguments
		const {
			option = 'interactive',
			alias = 'i',
			describe = 'Interactive mode',
			intro = 'Please provide the following values:',
			cancelled = 'Operation cancelled.',
			outro = 'Thank you!',
		} = this.options?.interactiveMode ?? {};

		const commandArgs = {
			...args,
			command: `${command} ${parameters.join(' ').replace(/</g, '[').replace(/>/g, ']')}`,
			usage: parameters.map((p) => `${command} ${p}`).join('\n'),
			handler: this.buildHandler(handler, {
				option,
				alias,
				intro,
				cancelled,
				outro,
				describe,
			}),
		} as Record<string, unknown>

		if (interactiveMode) {
			commandArgs.options = {
				...(commandArgs.options ?? {}),
				[option]: {
					alias,
					describe,
					type: 'boolean',
					default: false,
					hidden: true,
				},
			};
		}

		this.cli.command(commandArgs as unknown as Parameters<typeof this.cli.command>[0]);
		return this;
	}

	async run(args: string[]): Promise<void> {
		if (args.length > 0) {
			await this.cli.parse(args);
			return;
		}
		this.cli.showHelp();
	}

	test() {
		this.testMode = true;
		this.promptValues = {};
		const thisCli = this;
		return {
			promptValue(...args: PromptValueArgs) {
				const [testArg] = args;

				if (typeof testArg === 'string') {
					const [key, value] = args as [string, unknown];
					thisCli.promptValues[key] = thisCli.promptValues[key] ?? value;
				}

				if (Array.isArray(testArg)) {
					const [key, value] = testArg as [string, unknown];
					thisCli.promptValues[key] = thisCli.promptValues[key] ?? value;
				}

				if (typeof testArg === 'object' && testArg !== null) {
					Object.entries(testArg).forEach(([key, value]) => {
						thisCli.promptValues[key] = thisCli.promptValues[key] ?? value;
					});
				}

				return this;
			},
			async run(args: string[]): Promise<TestModeResult> {
				await thisCli.cli.parse(args);
				return thisCli.testModeResult;
			},
		};
	}
}