import { writable } from 'svelte/store';
import { browser } from '$app/environment';

export type ServerState = 'pending' | 'done' | 'failed' | 'held' | 'manual';

export interface PipelineDeployment {
    id: string;
    action: string;
    servers: Map<string, { state: ServerState; players: number | null; error: string | null }>;
    openedAt: number;
}

export const deployments = writable<Map<string, PipelineDeployment>>(new Map());

let source: EventSource | null = null;

function updateDeployment(id: string, mutate: (d: PipelineDeployment) => void): void {
    deployments.update((m) => {
        const existing = m.get(id) ?? { id, action: '', servers: new Map(), openedAt: Date.now() };
        mutate(existing);
        m.set(id, existing);
        return new Map(m);
    });
}

export function startPipelineStream(): (() => void) | undefined {
    if (!browser || source) return;
    source = new EventSource('/api/events/pipeline');
    source.addEventListener('open', () => window.dispatchEvent(new Event('ec:pipeline-connected')));
    source.addEventListener('beta-changed', event => {
        try { window.dispatchEvent(new CustomEvent('ec:beta-changed', { detail: JSON.parse((event as MessageEvent).data) })); }
        catch { /* Reconnect refreshes authoritative state if an event is malformed. */ }
    });
    for (const event of ['server-changed', 'server-state', 'deployment-opened', 'fleet-invalidated']) {
        source.addEventListener(event, () => window.dispatchEvent(new Event('ec:fleet-changed')));
    }

    source.addEventListener('deployment-opened', (evt) => {
        const data = JSON.parse((evt as MessageEvent).data) as { deploymentId: string; action: string; servers: string[] };
        updateDeployment(data.deploymentId, (d) => {
            d.action = data.action;
            for (const s of data.servers) {
                if (!d.servers.has(s)) d.servers.set(s, { state: 'pending', players: null, error: null });
            }
        });
    });

    source.addEventListener('server-state', (evt) => {
        const data = JSON.parse((evt as MessageEvent).data) as {
            deploymentId: string;
            server: string;
            state: ServerState;
            players: number | null;
            error: string | null;
        };
        updateDeployment(data.deploymentId, (d) => {
            d.servers.set(data.server, { state: data.state, players: data.players, error: data.error });
        });
    });
    return () => { source?.close(); source = null; };
}