import { JsonValue } from '$std/json/common.ts'

export type JsonCompatible = JsonValue | { toJSON(): JsonValue } | unknown

export function respondApi<
	Kind extends ApiPayload['kind'],
	Payload extends JsonCompatible,
>(
	kind: Kind,
	payload?: Payload,
	status?: number,
	statusText?: string,
): Response {
	if (kind === 'error') {
		return Response.json({
			kind: 'error',
			error: String(payload ?? ''),
		} as ApiPayload, {
			status: status ?? 500,
			statusText,
		})
	}

	return Response.json({
		kind: 'success',
		data: payload ?? null,
	} as ApiPayload)
}

export async function requestApi<
	Payload extends JsonCompatible | undefined,
	ApiResponse extends JsonCompatible,
>(
	route: string,
	method: 'GET' | 'POST' | 'DELETE' | 'PATCH',
	payload?: Payload | null,
): Promise<ApiResponse> {
	const csrf = getCookie('_CSRF') ?? ''

	const base = new URL('/api/', location.origin)
	const endpoint = new URL(
		route.startsWith('/') ? `.${route}` : route,
		base.href,
	)

	const response = await fetch(endpoint, {
		method,
		headers: {
			'Content-Type': 'application/json; charset=utf-8',
			'X-CSRF-TOKEN': csrf,
		},
		body: payload ? JSON.stringify(payload) : null,
	})
	const apiPayload = await response.json() as ApiPayload<ApiResponse>

	if (apiPayload.kind === 'error') {
		throw new Error(`api request error while getting "${endpoint.href}"`, {
			cause: apiPayload.error,
		})
	}

	return apiPayload.data
}

export type ApiPayload<ApiResponse extends JsonCompatible = never> = {
	kind: 'success'
	data: ApiResponse
} | {
	kind: 'error'
	error: string
}

function getCookie(name: string): string | undefined {
	const cookiesEntries = document.cookie.split(';').map((cookie) =>
		cookie.trim().split('=')
	)
	const cookies = Object.fromEntries(cookiesEntries)
	return cookies[name]
}