import {IncomingHttpHeaders, IncomingMessage, OutgoingHttpHeaders, request, RequestOptions} from 'http';
import {Method} from '../src/backend/common';
import {DataSource} from '../src/backend/data-source';

interface ClientParams {
	method: Method;
	path: string;
	headers?: IncomingHttpHeaders;
	body?: unknown;
}

type ResponseBody = Buffer | string | object;

export interface TestClient {
	(params: ClientParams): Promise<[IncomingMessage, ResponseBody?]>;
	acceptMediaType(mediaType: string): this;
	acceptLanguage(language: string): this;
	acceptCharset(charset: string): this;
	contentType(mediaType: string): this;
	contentCharset(charset: string): this;
}

export const createTestClient = (options: Omit<RequestOptions, 'method' | 'path'>): TestClient => {
	const additionalHeaders: OutgoingHttpHeaders = {};
	const client = (params: ClientParams) => new Promise<[IncomingMessage, ResponseBody?]>((resolve, reject) => {
		const {
			...etcAdditionalHeaders
		} = additionalHeaders;

		const headers: OutgoingHttpHeaders = {
			...(options.headers ?? {}),
			...etcAdditionalHeaders,
		};

		let contentTypeHeader: string | undefined;
		if (typeof params.body !== 'undefined') {
			contentTypeHeader = headers['content-type'] = params.headers?.['content-type'] ?? 'application/json';
		}

		const req = request({
			...options,
			method: params.method,
			path: params.path,
			headers,
		});

		req.on('response', (res) => {
			res.on('error', (err) => {
				reject(err);
			});

			let resBuffer: Buffer | undefined;
			res.on('data', (c) => {
				resBuffer = (
					typeof resBuffer === 'undefined'
						? Buffer.from(c)
						: Buffer.concat([resBuffer, c])
				);
			});

			res.on('close', () => {
				const acceptHeader = Array.isArray(headers['accept']) ? headers['accept'].join('; ') : headers['accept'];
				const contentTypeBase = acceptHeader ?? 'application/octet-stream';
				const [type, subtype] = contentTypeBase.split('/');
				const allSubtypes = subtype.split('+');
				if (typeof resBuffer !== 'undefined') {
					if (allSubtypes.includes('json')) {
						const acceptCharset = (
							Array.isArray(headers['accept-charset'])
								? headers['accept-charset'].join('; ')
								: headers['accept-charset']
						) as BufferEncoding | undefined;
						resolve([res, JSON.parse(resBuffer.toString(acceptCharset ?? 'utf-8'))]);
						return;
					}

					if (type === 'text') {
						const acceptCharset = (
							Array.isArray(headers['accept-charset'])
								? headers['accept-charset'].join('; ')
								: headers['accept-charset']
						) as BufferEncoding | undefined;
						resolve([res, resBuffer.toString(acceptCharset ?? 'utf-8')]);
						return;
					}

					resolve([res, resBuffer]);
					return;
				}

				resolve([res]);
			});
		});

		req.on('error', (err) => {
			reject(err);
		})

		if (typeof params.body !== 'undefined') {
			const theContentTypeHeader = Array.isArray(contentTypeHeader) ? contentTypeHeader.join('; ') : contentTypeHeader?.toString();
			const contentTypeAll = theContentTypeHeader ?? 'application/octet-stream';
			const [contentTypeBase, ...contentTypeParams] = contentTypeAll.split(';').map((s) => s.replace(/\s+/g, '').trim());
			const charsetParam = contentTypeParams.find((s) => s.startsWith('charset='));
			const charset = charsetParam?.split('=')?.[1] as BufferEncoding | undefined;
			const [, subtype] = contentTypeBase.split('/');
			const allSubtypes = subtype.split('+');
			req.write(
				allSubtypes.includes('json')
					? JSON.stringify(params.body)
					: Buffer.from(params.body?.toString() ?? '', contentTypeBase === 'text' ? charset : undefined)
			);
		}

		req.end();
	});

	client.acceptMediaType = function acceptMediaType(mediaType: string) {
		additionalHeaders['accept'] = mediaType;
		return this;
	};

	client.acceptLanguage = function acceptLanguage(language: string) {
		additionalHeaders['accept-language'] = language;
		return this;
	};

	client.acceptCharset = function acceptCharset(charset: string) {
		additionalHeaders['accept-charset'] = charset;
		return this;
	};

	client.contentType = function contentType(mediaType: string) {
		additionalHeaders['content-type'] = mediaType;
		return this;
	};

	client.contentCharset = function contentCharset(charset: string) {
		additionalHeaders['content-type'] = `${additionalHeaders['content-type']}; charset="${charset}"`;
		return this;
	};

	return client;
};

export class DummyError extends Error {}

export class DummyDataSource implements DataSource {
	private resource?: { dataSource?: unknown };

	create(): Promise<never> {
		throw new DummyError();
	}

	delete(): Promise<never> {
		throw new DummyError();
	}

	emplace(): Promise<never> {
		throw new DummyError();
	}

	getById(): Promise<never> {
		throw new DummyError();
	}

	newId(): Promise<never> {
		throw new DummyError();
	}

	getMultiple(): Promise<never> {
		throw new DummyError();
	}

	getSingle(): Promise<never> {
		throw new DummyError();
	}

	getTotalCount(): Promise<never> {
		throw new DummyError();
	}

	async initialize(): Promise<void> {}

	patch(): Promise<never> {
		throw new DummyError();
	}

	prepareResource(rr: unknown) {
		this.resource = rr as unknown as { dataSource: DummyDataSource };
		this.resource.dataSource = this;
	}
}