/* Transfers on the phone: the downloads the backend is running — every
   Save lands here — fed by soulseek:download exactly as the desktop's
   `downloads` store is (latest update wins, a terminal update without
   numbers keeps the last known progress), pruned once a burst drains. */
import * as api from "../lib/api.js";
import { listen } from "../lib/events.js";

export const transfers = $state({
    /** id → payload { id, username, path, name, state, queue_place, local_path, error, received, total } */
    items: {},
});

export const DONE = new Set(["complete", "failed", "cancelled"]);
const HISTORY_MAX = 60;

export function list() {
    return Object.values(transfers.items).sort((a, b) => b.id - a.id);
}
export function active() {
    return Object.values(transfers.items).filter((d) => !DONE.has(d.state));
}
export function clearFinished() {
    for (const d of Object.values(transfers.items)) if (DONE.has(d.state)) delete transfers.items[d.id];
}
export async function cancel(id) {
    try { await api.cancelDownload(id); } catch { /* already gone */ }
}

/** "queued · 3rd in line", "transferring · 42%", "saved", "failed · reason" */
export function stateLine(d) {
    switch (d.state) {
        case "connecting": return "connecting…";
        case "requested": return "asked…";
        case "queued": return d.queue_place ? `queued · ${d.queue_place} ahead` : "queued";
        case "transferring": return d.total ? `${Math.round((d.received / d.total) * 100)}%` : "transferring…";
        case "complete": return "saved";
        case "failed": return d.error ? `failed · ${d.error}` : "failed";
        case "cancelled": return "cancelled";
        default: return d.state || "";
    }
}

let bound = false;
export async function bindTransfers() {
    if (bound) return;
    bound = true;
    try {
        await listen("soulseek:download", (ev) => {
            const d = ev.payload;
            if (!d || d.id == null) return;
            const prev = transfers.items[d.id];
            if (prev && !d.total) { d.received = prev.received; d.total = prev.total; }
            transfers.items[d.id] = d;
            if (DONE.has(d.state)) {
                /* keep an active burst whole; prune the oldest finished past the cap */
                const done = Object.values(transfers.items).filter((x) => DONE.has(x.state)).sort((a, b) => a.id - b.id);
                for (const x of done.slice(0, Math.max(0, done.length - HISTORY_MAX))) delete transfers.items[x.id];
            }
        });
    } catch { /* not a phone */ }
}