import { error, redirect } from '@sveltejs/kit'
import type { RequestEvent } from '@sveltejs/kit'
import { getSessionUser } from '$lib/server/admin/session'

type FetchInput = Parameters<typeof fetch>[0]

export type AdminFetchOptions = RequestInit

export interface AdminFetchJsonOptions extends AdminFetchOptions {
	parse?: 'json' | 'text' | 'response'
}

function adminPassword(): string {
	return process.env.ADMIN_PASSWORD ?? 'changeme'
}

function withAuthHeader(init: RequestInit = {}): RequestInit {
	const headers = new Headers(init.headers ?? {})
	if (!headers.has('Authorization')) {
		const credentials = Buffer.from(`admin:${adminPassword()}`).toString('base64')
		headers.set('Authorization', `Basic ${credentials}`)
	}

	return {
		...init,
		headers
	}
}

export async function adminFetch(
	event: RequestEvent,
	input: FetchInput,
	options: AdminFetchOptions = {}
): Promise<Response> {
	const user = getSessionUser(event.cookies)
	if (!user) {
		throw redirect(303, '/admin/login')
	}

	const init = withAuthHeader(options)
	const response = await event.fetch(input, init)

	if (response.status === 401) {
		throw redirect(303, '/admin/login')
	}

	if (!response.ok) {
		let detail: string | undefined
		try {
			const json = await response.clone().json()
			detail = typeof json === 'object' && json !== null && 'error' in json ? String(json.error) : undefined
		} catch {
			try {
				detail = await response.clone().text()
			} catch {
				detail = undefined
			}
		}

		throw error(response.status, detail || 'Admin request failed')
	}

	return response
}

export async function adminFetchJson<T>(
	event: RequestEvent,
	input: FetchInput,
	options: AdminFetchJsonOptions = {}
): Promise<T> {
	const { parse = 'json', ...fetchOptions } = options
	const response = await adminFetch(event, input, fetchOptions)

	if (parse === 'text') {
		return (await response.text()) as unknown as T
	}

	if (parse === 'response') {
		return response as unknown as T
	}

	return response.json() as Promise<T>
}