import { writable, readonly } from 'svelte/store';
import { browser } from '$app/environment';
import type { GameTelemetry } from '$lib/telemetry.js';

export const telemetryByServer = writable<Map<string, GameTelemetry>>(new Map());
export const matchEventsByServer = writable<Map<string, GameTelemetry>>(new Map());

export interface RosterPlayer {
    num: number | null;
    score: number;
    ping: number;
    guid: string | null;
    name: string;
}

export type Health = 'online' | 'stale' | 'offline' | 'starting' | 'provisioning';
export type RconFailure = 'no-config' | 'no-port' | 'send-error' | 'timeout' | 'bad-reply' | 'no-players';

export interface RconEndpoint {
    host: string;
    port: number;
}

export interface ServerStatus {
    server: string;
    players: number | null;
    map: string | null;
    gametype: string | null;
    roster: RosterPlayer[] | null;
    health: Health;
    lastSeenAt: string | null;
    lastError: string | null;
    endpoint: RconEndpoint | null;
    reason: RconFailure | null;
    replySnippet: string | null;
    activeSince: string | null;
    inactiveSince: string | null;
    gameStartedAt: string | null;
    gameEndedAt: string | null;
}

export const statusByServer = writable<Map<string, ServerStatus>>(new Map());
export const statusReceivedAt = writable(0);

// Shared 1s ticker for elapsed-time displays. One interval feeds every card
// on the page instead of N per-card timers. Timer starts on the first
// startServerStream() call in the browser.
const _uiNow = writable(Date.now());
export const uiNow = readonly(_uiNow);
let serverClock: { time: number; receivedAt: number } | null = null;

// Report timestamps belong to the backend clock, which can differ from the
// browser's wall clock. Advance that clock locally even if updates stop.
export function serverTimeNow(): number {
    return serverClock ? serverClock.time + performance.now() - serverClock.receivedAt : Date.now();
}

export function syncServerTime(serverNow?: number): void {
    if (typeof serverNow === 'number' && Number.isFinite(serverNow)) {
        // A delayed HTTP snapshot must not rewind time behind a newer stream
        // update and make that update look like it came from the future.
        const time = serverClock ? Math.max(serverNow, serverTimeNow()) : serverNow;
        serverClock = { time, receivedAt: performance.now() };
    }
    // Refresh immediately: a suspended tab's interval may be well behind.
    _uiNow.set(serverTimeNow());
}

let tickInterval: ReturnType<typeof setInterval> | null = null;

let source: EventSource | null = null;

export function startServerStream(): (() => void) | undefined {
    if (!browser || source) return;
    syncServerTime();
    source = new EventSource('/api/events/servers');
    source.addEventListener('server-telemetry', (evt) => {
        const data = JSON.parse((evt as MessageEvent).data) as { entries: GameTelemetry[]; snapshot?: boolean; serverNow?: number };
        syncServerTime(data.serverNow);
        matchEventsByServer.update((previous) => {
            const next = data.snapshot ? new Map<string, GameTelemetry>() : new Map(previous);
            for (const entry of data.entries) {
                if (entry.event === 'game_start' || entry.event === 'game_end') next.set(entry.server, entry);
            }
            return next;
        });
        telemetryByServer.update((previous) => {
            const next = data.snapshot ? new Map<string, GameTelemetry>() : new Map(previous);
            for (const entry of data.entries) next.set(entry.server, entry);
            return next;
        });
    });
    source.addEventListener('server-status', (evt) => {
        const data = JSON.parse((evt as MessageEvent).data) as { entries: ServerStatus[]; serverNow?: number };
        syncServerTime(data.serverNow);
        statusByServer.update(() => {
            const m = new Map<string, ServerStatus>();
            for (const e of data.entries) m.set(e.server, e);
            return m;
        });
        statusReceivedAt.set(Date.now());
    });
    if (tickInterval === null) {
        tickInterval = setInterval(() => _uiNow.set(serverTimeNow()), 1000);
    }
    return () => { source?.close(); source = null; if (tickInterval) clearInterval(tickInterval); tickInterval = null; };
}