import { browser } from '$app/environment';

export const TOKEN_STORAGE_KEY = 'evobgp_api_token';

export type Problem = {
	title?: string;
	status?: number;
	detail?: string;
};

function mergeHeaders(init?: RequestInit): Headers {
	const h = new Headers(init?.headers);
	if (!h.has('Accept')) {
		h.set('Accept', 'application/json');
	}
	if (browser) {
		const t = localStorage.getItem(TOKEN_STORAGE_KEY);
		if (t && !h.has('Authorization')) {
			h.set('Authorization', `Bearer ${t}`);
		}
	}
	return h;
}

export async function apiFetch(path: string, init?: RequestInit): Promise<Response> {
	if (!browser) {
		throw new Error('API is only available in the browser');
	}
	return fetch(path, { ...init, headers: mergeHeaders(init) });
}

export async function apiJSON<T>(path: string, init?: RequestInit): Promise<T> {
	const res = await apiFetch(path, init);
	const text = await res.text();
	if (!res.ok) {
		let detail = text;
		try {
			const j = JSON.parse(text) as Problem;
			if (j?.detail) detail = j.detail;
		} catch {
			/* plain text */
		}
		throw new Error(detail || `HTTP ${res.status}`);
	}
	if (!text) return undefined as T;
	return JSON.parse(text) as T;
}