import { user } from '$lib/stores/user';
import { get } from 'svelte/store';
import { Err, Ok, type Result } from './utilities';

export namespace api {
	export function get<TResponse>(endpoint: string, params?: RequestInit) {
		return sendRequest<TResponse>(endpoint, 'GET', null, params);
	}

	export function post<TResponse>(endpoint: string, data?: unknown) {
		return sendRequest<TResponse>(endpoint, 'POST', data);
	}

	export function put<TResponse>(endpoint: string, data?: unknown) {
		return sendRequest<TResponse>(endpoint, 'PUT', data);
	}

	export function remove<TResponse>(endpoint: string) {
		return sendRequest<TResponse>(endpoint, 'DELETE');
	}
}

async function sendRequest<TResponse>(
	endpoint: string,
	method: string,
	data?: unknown,
	params?: RequestInit
): Promise<Result<TResponse, Error>> {
	const user_token = get(user).bearer_token;
	const body = data !== null && typeof data !== 'undefined' ? JSON.stringify(data) : undefined;

	const request = {
		...params,
		method,
		body,
		headers: {
			...params?.headers,
			Authorization: user_token ? 'Bearer ' + user_token : 'Basic',
			'Content-Type': 'application/json'
		}
	};

	let response;

	try {
		response = await fetch(endpoint, request);
	} catch (error) {
		return Err.new(new Error(), 'An error has occurred');
	}

	const isResponseOk = response.status >= 200 && response.status < 400;
	if (!isResponseOk) {
		if (response.status === 401) {
			return Err.new(new ApiError(response), 'User was not authorized');
		}
		return Err.new(new ApiError(response), 'An error has occurred');
	}

	const contentType = response.headers.get('Content-Type') ?? response.headers.get('Content-Type');
	if (contentType && contentType.includes('application/json')) {
		const data = await response.json();
		return Ok.new(data as TResponse);
	} else {
		// Handle empty object as response
		return Ok.new(null as TResponse);
	}
}

export class ApiError extends Error {
	constructor(public readonly response: Response) {
		super(`${response.status}`);
	}
}