// Mutates the in-memory fleet over time so the UI shows live activity:
// speeds fluctuate, downloads progress, pieces fill in, ETA/ratio drift,
// session totals accumulate, and the occasional torrent completes.

import { db, constants } from './data.js';

const { KiB, MiB } = constants;

function clamp(v, lo, hi) { return Math.max(lo, Math.min(hi, v)); }
function jitter(v, frac) { return v * (1 + (Math.random() * 2 - 1) * frac); }

const DL_STATES = new Set(['downloading', 'forcedDL', 'metaDL']);
const UP_STATES = new Set(['uploading', 'forcedUP']);

export function tick() {
  const now = Date.now();
  for (const t of db.torrents) {
    const isDL = DL_STATES.has(t.state);
    const isUP = UP_STATES.has(t.state) || isDL;

    // --- speeds ---
    if (isDL) {
      const ceiling = t.downLimit > 0 ? t.downLimit : 18 * MiB;
      t.dlspeed = clamp(Math.round(jitter(t.dlspeed || 500 * KiB, 0.4)), 20 * KiB, ceiling);
      // occasionally stall
      if (Math.random() < 0.03) { t.state = 'stalledDL'; t.dlspeed = 0; }
    } else if (t.state === 'stalledDL') {
      t.dlspeed = 0;
      if (Math.random() < 0.08) { t.state = 'downloading'; t.dlspeed = 800 * KiB; }
    } else {
      t.dlspeed = 0;
    }

    if (isUP) {
      const ceiling = t.upLimit > 0 ? t.upLimit : 6 * MiB;
      t.upspeed = clamp(Math.round(jitter(t.upspeed || 100 * KiB, 0.5)), 0, ceiling);
    } else {
      t.upspeed = 0;
    }

    // --- progress ---
    if (isDL && t.progress < 1 && t.dlspeed > 0) {
      const gained = t.dlspeed; // ~1s of bytes
      t.downloaded += gained;
      t.downloadedSession += gained;
      t.progress = clamp(t.progress + gained / t.size, 0, 1);

      // fill some pieces proportionally
      const targetDone = Math.floor(t.pieceCount * t.progress);
      let done = 0;
      for (const p of t.pieces) if (p === 2) done++;
      let toFill = targetDone - done;
      for (let i = 0; i < t.pieces.length && toFill > 0; i++) {
        if (t.pieces[i] !== 2) {
          if (t.pieces[i] === 1 || Math.random() < 0.5) { t.pieces[i] = 2; toFill--; }
          else t.pieces[i] = 1;
        }
      }

      if (t.state === 'metaDL' && t.progress > 0.01) t.state = 'downloading';

      // completion
      if (t.progress >= 1) {
        t.progress = 1;
        t.state = 'uploading';
        t.completionOn = now;
        t.dlspeed = 0;
        for (let i = 0; i < t.pieces.length; i++) t.pieces[i] = 2;
      }
    }

    // --- uploaded / ratio ---
    if (t.upspeed > 0) {
      t.uploaded += t.upspeed;
      t.uploadedSession += t.upspeed;
    }
    t.ratio = t.downloaded > 0 ? t.uploaded / t.downloaded : (t.uploaded > 0 ? 9999 : 0);

    // --- eta ---
    t.eta = isDL && t.dlspeed > 0
      ? Math.floor((t.size - t.downloaded) / t.dlspeed)
      : 8640000;

    // --- swarm drift ---
    if (!t.state.startsWith('paused')) {
      t.seeds = clamp(t.seeds + (Math.random() < 0.5 ? -1 : 1) * (Math.random() < 0.3 ? 1 : 0), 0, t.seedsTotal);
      t.peers = clamp(t.peers + (Math.random() < 0.5 ? -1 : 1) * (Math.random() < 0.3 ? 1 : 0), 0, t.peersTotal);
      t.lastActivity = now;
      t.timeActive += 1;
    }

    // --- peer speeds drift ---
    for (const p of t.peersList) {
      if (p.dlspeed) p.dlspeed = clamp(Math.round(jitter(p.dlspeed, 0.5)), 0, 4 * MiB);
      if (p.upspeed) p.upspeed = clamp(Math.round(jitter(p.upspeed, 0.5)), 0, 800 * KiB);
      if (p.progress < 1) p.progress = clamp(p.progress + Math.random() * 0.01, 0, 1);
    }
  }
}

// Global session/server stats derived from the fleet.
export function globalStats() {
  let dl = 0, up = 0, dlSession = 0, upSession = 0, totalDown = 0, totalUp = 0;
  let active = 0;
  for (const t of db.torrents) {
    dl += t.dlspeed;
    up += t.upspeed;
    dlSession += t.downloadedSession;
    upSession += t.uploadedSession;
    totalDown += t.downloaded;
    totalUp += t.uploaded;
    if (t.dlspeed > 0 || t.upspeed > 0) active++;
  }
  const p = db.preferences;
  return {
    dl_info_speed: dl,
    up_info_speed: up,
    dl_info_data: dlSession,
    up_info_data: upSession,
    dl_rate_limit: p.alt_speed_enabled ? p.alt_dl_limit : p.dl_limit,
    up_rate_limit: p.alt_speed_enabled ? p.alt_up_limit : p.up_limit,
    alt_speed_enabled: p.alt_speed_enabled,
    global_ratio: totalDown > 0 ? totalUp / totalDown : 0,
    dht_nodes: 312 + Math.floor(Math.random() * 40),
    connection_status: 'connected',
    listen_port: p.listen_port,
    free_space: 812 * 1024 * 1024 * 1024 + Math.floor(Math.random() * 1e9),
    active_torrents: active,
    total_torrents: db.torrents.length,
    queued_io_jobs: Math.floor(Math.random() * 4),
    read_cache_hits: (88 + Math.random() * 8).toFixed(1),
    total_buffer_size: 16 * MiB,
    average_time_queue: Math.floor(Math.random() * 12),
  };
}