/*! MIT License © Sindre Sorhus */

const globals = {};

const getGlobal = property => {
	/* istanbul ignore next */
	if (typeof self !== 'undefined' && self && property in self) {
		return self;
	}

	/* istanbul ignore next */
	if (typeof window !== 'undefined' && window && property in window) {
		return window;
	}

	if (typeof global !== 'undefined' && global && property in global) {
		return global;
	}

	/* istanbul ignore next */
	if (typeof globalThis !== 'undefined' && globalThis) {
		return globalThis;
	}
};

const globalProperties = [
	'Headers',
	'Request',
	'Response',
	'ReadableStream',
	'fetch',
	'AbortController',
	'FormData'
];

for (const property of globalProperties) {
	Object.defineProperty(globals, property, {
		get() {
			const globalObject = getGlobal(property);
			const value = globalObject && globalObject[property];
			return typeof value === 'function' ? value.bind(globalObject) : value;
		}
	});
}

const isObject = value => value !== null && typeof value === 'object';
const supportsAbortController = typeof globals.AbortController === 'function';
const supportsStreams = typeof globals.ReadableStream === 'function';
const supportsFormData = typeof globals.FormData === 'function';

const mergeHeaders = (source1, source2) => {
	const result = new globals.Headers(source1 || {});
	const isHeadersInstance = source2 instanceof globals.Headers;
	const source = new globals.Headers(source2 || {});

	for (const [key, value] of source) {
		if ((isHeadersInstance && value === 'undefined') || value === undefined) {
			result.delete(key);
		} else {
			result.set(key, value);
		}
	}

	return result;
};

const deepMerge = (...sources) => {
	let returnValue = {};
	let headers = {};

	for (const source of sources) {
		if (Array.isArray(source)) {
			if (!(Array.isArray(returnValue))) {
				returnValue = [];
			}

			returnValue = [...returnValue, ...source];
		} else if (isObject(source)) {
			for (let [key, value] of Object.entries(source)) {
				if (isObject(value) && (key in returnValue)) {
					value = deepMerge(returnValue[key], value);
				}

				returnValue = {...returnValue, [key]: value};
			}

			if (isObject(source.headers)) {
				headers = mergeHeaders(headers, source.headers);
			}
		}

		returnValue.headers = headers;
	}

	return returnValue;
};

const requestMethods = [
	'get',
	'post',
	'put',
	'patch',
	'head',
	'delete'
];

const responseTypes = {
	json: 'application/json',
	text: 'text/*',
	formData: 'multipart/form-data',
	arrayBuffer: '*/*',
	blob: '*/*'
};

const retryMethods = [
	'get',
	'put',
	'head',
	'delete',
	'options',
	'trace'
];

const retryStatusCodes = [
	408,
	413,
	429,
	500,
	502,
	503,
	504
];

const retryAfterStatusCodes = [
	413,
	429,
	503
];

const stop = Symbol('stop');

class HTTPError extends Error {
	constructor(response) {
		// Set the message to the status text, such as Unauthorized,
		// with some fallbacks. This message should never be undefined.
		super(
			response.statusText ||
			String(
				(response.status === 0 || response.status) ?
					response.status : 'Unknown response error'
			)
		);
		this.name = 'HTTPError';
		this.response = response;
	}
}

class TimeoutError extends Error {
	constructor(request) {
		super('Request timed out');
		this.name = 'TimeoutError';
		this.request = request;
	}
}

const delay = ms => new Promise(resolve => setTimeout(resolve, ms));

// `Promise.race()` workaround (#91)
const timeout = (request, abortController, options) =>
	new Promise((resolve, reject) => {
		const timeoutID = setTimeout(() => {
			if (abortController) {
				abortController.abort();
			}

			reject(new TimeoutError(request));
		}, options.timeout);

		/* eslint-disable promise/prefer-await-to-then */
		options.fetch(request)
			.then(resolve)
			.catch(reject)
			.then(() => {
				clearTimeout(timeoutID);
			});
		/* eslint-enable promise/prefer-await-to-then */
	});

const normalizeRequestMethod = input => requestMethods.includes(input) ? input.toUpperCase() : input;

const defaultRetryOptions = {
	limit: 2,
	methods: retryMethods,
	statusCodes: retryStatusCodes,
	afterStatusCodes: retryAfterStatusCodes
};

const normalizeRetryOptions = (retry = {}) => {
	if (typeof retry === 'number') {
		return {
			...defaultRetryOptions,
			limit: retry
		};
	}

	if (retry.methods && !Array.isArray(retry.methods)) {
		throw new Error('retry.methods must be an array');
	}

	if (retry.statusCodes && !Array.isArray(retry.statusCodes)) {
		throw new Error('retry.statusCodes must be an array');
	}

	return {
		...defaultRetryOptions,
		...retry,
		afterStatusCodes: retryAfterStatusCodes
	};
};

// The maximum value of a 32bit int (see issue #117)
const maxSafeTimeout = 2147483647;

class Ky {
	constructor(input, options = {}) {
		this._retryCount = 0;
		this._input = input;
		this._options = {
			// TODO: credentials can be removed when the spec change is implemented in all browsers. Context: https://www.chromestatus.com/feature/4539473312350208
			credentials: this._input.credentials || 'same-origin',
			...options,
			headers: mergeHeaders(this._input.headers, options.headers),
			hooks: deepMerge({
				beforeRequest: [],
				beforeRetry: [],
				afterResponse: []
			}, options.hooks),
			method: normalizeRequestMethod(options.method || this._input.method),
			prefixUrl: String(options.prefixUrl || ''),
			retry: normalizeRetryOptions(options.retry),
			throwHttpErrors: options.throwHttpErrors !== false,
			timeout: typeof options.timeout === 'undefined' ? 10000 : options.timeout,
			fetch: options.fetch || globals.fetch
		};

		if (typeof this._input !== 'string' && !(this._input instanceof URL || this._input instanceof globals.Request)) {
			throw new TypeError('`input` must be a string, URL, or Request');
		}

		if (this._options.prefixUrl && typeof this._input === 'string') {
			if (this._input.startsWith('/')) {
				throw new Error('`input` must not begin with a slash when using `prefixUrl`');
			}

			if (!this._options.prefixUrl.endsWith('/')) {
				this._options.prefixUrl += '/';
			}

			this._input = this._options.prefixUrl + this._input;
		}

		if (supportsAbortController) {
			this.abortController = new globals.AbortController();
			if (this._options.signal) {
				this._options.signal.addEventListener('abort', () => {
					this.abortController.abort();
				});
			}

			this._options.signal = this.abortController.signal;
		}

		this.request = new globals.Request(this._input, this._options);

		if (this._options.searchParams) {
			const searchParams = '?' + new URLSearchParams(this._options.searchParams).toString();
			const url = this.request.url.replace(/(?:\?.*?)?(?=#|$)/, searchParams);

			// To provide correct form boundary, Content-Type header should be deleted each time when new Request instantiated from another one
			if (((supportsFormData && this._options.body instanceof globals.FormData) || this._options.body instanceof URLSearchParams) && !(this._options.headers && this._options.headers['content-type'])) {
				this.request.headers.delete('content-type');
			}

			this.request = new globals.Request(new globals.Request(url, this.request), this._options);
		}

		if (this._options.json !== undefined) {
			this._options.body = JSON.stringify(this._options.json);
			this.request.headers.set('content-type', 'application/json');
			this.request = new globals.Request(this.request, {body: this._options.body});
		}

		const fn = async () => {
			if (this._options.timeout > maxSafeTimeout) {
				throw new RangeError(`The \`timeout\` option cannot be greater than ${maxSafeTimeout}`);
			}

			await delay(1);
			let response = await this._fetch();

			for (const hook of this._options.hooks.afterResponse) {
				// eslint-disable-next-line no-await-in-loop
				const modifiedResponse = await hook(
					this.request,
					this._options,
					this._decorateResponse(response.clone())
				);

				if (modifiedResponse instanceof globals.Response) {
					response = modifiedResponse;
				}
			}

			this._decorateResponse(response);

			if (!response.ok && this._options.throwHttpErrors) {
				throw new HTTPError(response);
			}

			// If `onDownloadProgress` is passed, it uses the stream API internally
			/* istanbul ignore next */
			if (this._options.onDownloadProgress) {
				if (typeof this._options.onDownloadProgress !== 'function') {
					throw new TypeError('The `onDownloadProgress` option must be a function');
				}

				if (!supportsStreams) {
					throw new Error('Streams are not supported in your environment. `ReadableStream` is missing.');
				}

				return this._stream(response.clone(), this._options.onDownloadProgress);
			}

			return response;
		};

		const isRetriableMethod = this._options.retry.methods.includes(this.request.method.toLowerCase());
		const result = isRetriableMethod ? this._retry(fn) : fn();

		for (const [type, mimeType] of Object.entries(responseTypes)) {
			result[type] = async () => {
				this.request.headers.set('accept', this.request.headers.get('accept') || mimeType);

				const response = (await result).clone();

				if (type === 'json') {
					if (response.status === 204) {
						return '';
					}

					if (options.parseJson) {
						return options.parseJson(await response.text());
					}
				}

				return response[type]();
			};
		}

		return result;
	}

	_calculateRetryDelay(error) {
		this._retryCount++;

		if (this._retryCount < this._options.retry.limit && !(error instanceof TimeoutError)) {
			if (error instanceof HTTPError) {
				if (!this._options.retry.statusCodes.includes(error.response.status)) {
					return 0;
				}

				const retryAfter = error.response.headers.get('Retry-After');
				if (retryAfter && this._options.retry.afterStatusCodes.includes(error.response.status)) {
					let after = Number(retryAfter);
					if (Number.isNaN(after)) {
						after = Date.parse(retryAfter) - Date.now();
					} else {
						after *= 1000;
					}

					if (typeof this._options.retry.maxRetryAfter !== 'undefined' && after > this._options.retry.maxRetryAfter) {
						return 0;
					}

					return after;
				}

				if (error.response.status === 413) {
					return 0;
				}
			}

			const BACKOFF_FACTOR = 0.3;
			return BACKOFF_FACTOR * (2 ** (this._retryCount - 1)) * 1000;
		}

		return 0;
	}

	_decorateResponse(response) {
		if (this._options.parseJson) {
			response.json = async () => {
				return this._options.parseJson(await response.text());
			};
		}

		return response;
	}

	async _retry(fn) {
		try {
			return await fn();
		} catch (error) {
			const ms = Math.min(this._calculateRetryDelay(error), maxSafeTimeout);
			if (ms !== 0 && this._retryCount > 0) {
				await delay(ms);

				for (const hook of this._options.hooks.beforeRetry) {
					// eslint-disable-next-line no-await-in-loop
					const hookResult = await hook({
						request: this.request,
						options: this._options,
						error,
						retryCount: this._retryCount
					});

					// If `stop` is returned from the hook, the retry process is stopped
					if (hookResult === stop) {
						return;
					}
				}

				return this._retry(fn);
			}

			if (this._options.throwHttpErrors) {
				throw error;
			}
		}
	}

	async _fetch() {
		for (const hook of this._options.hooks.beforeRequest) {
			// eslint-disable-next-line no-await-in-loop
			const result = await hook(this.request, this._options);

			if (result instanceof Request) {
				this.request = result;
				break;
			}

			if (result instanceof Response) {
				return result;
			}
		}

		if (this._options.timeout === false) {
			return this._options.fetch(this.request.clone());
		}

		return timeout(this.request.clone(), this.abortController, this._options);
	}

	/* istanbul ignore next */
	_stream(response, onDownloadProgress) {
		const totalBytes = Number(response.headers.get('content-length')) || 0;
		let transferredBytes = 0;

		return new globals.Response(
			new globals.ReadableStream({
				start(controller) {
					const reader = response.body.getReader();

					if (onDownloadProgress) {
						onDownloadProgress({percent: 0, transferredBytes: 0, totalBytes}, new Uint8Array());
					}

					async function read() {
						const {done, value} = await reader.read();
						if (done) {
							controller.close();
							return;
						}

						if (onDownloadProgress) {
							transferredBytes += value.byteLength;
							const percent = totalBytes === 0 ? 0 : transferredBytes / totalBytes;
							onDownloadProgress({percent, transferredBytes, totalBytes}, value);
						}

						controller.enqueue(value);
						read();
					}

					read();
				}
			})
		);
	}
}

const validateAndMerge = (...sources) => {
	for (const source of sources) {
		if ((!isObject(source) || Array.isArray(source)) && typeof source !== 'undefined') {
			throw new TypeError('The `options` argument must be an object');
		}
	}

	return deepMerge({}, ...sources);
};

const createInstance = defaults => {
	const ky = (input, options) => new Ky(input, validateAndMerge(defaults, options));

	for (const method of requestMethods) {
		ky[method] = (input, options) => new Ky(input, validateAndMerge(defaults, options, {method}));
	}

	ky.HTTPError = HTTPError;
	ky.TimeoutError = TimeoutError;
	ky.create = newDefaults => createInstance(validateAndMerge(newDefaults));
	ky.extend = newDefaults => createInstance(validateAndMerge(defaults, newDefaults));
	ky.stop = stop;

	return ky;
};

export default createInstance();