import type { LogEntry, LogLevel, Logger } from '../logger.js';

/** A `LogEntry` tagged with where it came from, for display in `DebugPanel.svelte`. */
export interface DisplayLogEntry extends LogEntry {
	source: 'client' | 'server';
}

const MAX_ENTRIES = 500;

let entries: DisplayLogEntry[] = [];
const subscribers = new Set<(entries: DisplayLogEntry[]) => void>();

function notify(): void {
	for (const run of subscribers) run(entries);
}

function push(entry: DisplayLogEntry): void {
	entries = entries.length >= MAX_ENTRIES ? [...entries.slice(1), entry] : [...entries, entry];
	notify();
}

/**
 * Feeds a server-forwarded `debug.log` entry into the same shared buffer the
 * panel renders. Not for direct use by app code — call `clientLogger` for
 * anything happening in the browser itself; this is exported specifically
 * for `server-log-forwarder.ts`.
 */
export function pushLogEntry(entry: LogEntry, source: DisplayLogEntry['source'] = 'server'): void {
	push({ ...entry, source });
}

function log(level: LogLevel, category: string, message: string, data?: unknown): void {
	if (data === undefined) {
		console[level](`[${category}] ${message}`);
	} else {
		console[level](`[${category}] ${message}`, data);
	}
	push({ level, category, message, data, timestamp: Date.now(), source: 'client' });
}

/**
 * Ambient client-side logger — any browser code (with or without a realtime
 * connection) can call this directly, e.g. `clientLogger.warn('ws', ...)`.
 * Feeds the same shared buffer `DebugPanel.svelte` renders.
 */
export const clientLogger: Logger = {
	debug: (category, message, data) => log('debug', category, message, data),
	info: (category, message, data) => log('info', category, message, data),
	warn: (category, message, data) => log('warn', category, message, data),
	error: (category, message, data) => log('error', category, message, data)
};

/**
 * Read-only, Svelte-store-compatible view of the shared log buffer (client
 * entries plus anything forwarded from the server) — hand-rolled the same
 * way as `$lib/client/humanoid/avatar-state.ts`'s `deriveAvatarState`; no
 * `svelte/store` import anywhere in this repo, and this doesn't start one.
 */
export const debugLogStore = {
	subscribe(run: (entries: DisplayLogEntry[]) => void): () => void {
		subscribers.add(run);
		run(entries);
		return () => subscribers.delete(run);
	}
};

export function clearLogs(): void {
	entries = [];
	notify();
}