/**
 * quality.js — Detect hardware capability and return a quality tier.
 *
 * Tiers:
 *   'low'    — older iPads, phones, low-end GPUs (reduce particles, simpler effects)
 *   'medium' — mid-range (moderate particle count)
 *   'high'   — desktop, modern iPad Pro (full quality)
 *
 * Detection uses a combination of:
 *   - Device pixel ratio (low DPR = likely low-end)
 *   - Logical core count (navigator.hardwareConcurrency)
 *   - Device memory (navigator.deviceMemory, Chrome/Edge only)
 *   - Screen size (small viewport = likely mobile)
 *   - Touch capability (touch + small screen = phone/tablet)
 *   - WebGL renderer string (if available)
 */

let cachedTier = null;

export function getQualityTier() {
  if (cachedTier) return cachedTier;

  let score = 0;

  // Core count: 1-2 = low, 4 = mid, 8+ = high
  const cores = navigator.hardwareConcurrency || 2;
  if (cores >= 8) score += 3;
  else if (cores >= 4) score += 2;
  else score += 0;

  // Device memory (Chrome/Edge): < 4GB = low, 4-8 = mid, 8+ = high
  const mem = navigator.deviceMemory || 4;
  if (mem >= 8) score += 3;
  else if (mem >= 4) score += 2;
  else score += 0;

  // Screen dimensions (logical pixels)
  const maxDim = Math.max(window.screen.width, window.screen.height);
  if (maxDim < 768) score -= 1;   // phone
  else if (maxDim >= 1920) score += 1; // large desktop

  // DPR: high DPR on small screens = more GPU work
  const dpr = window.devicePixelRatio || 1;
  if (dpr > 2 && maxDim < 1024) score -= 1; // retina phone

  // Touch-only device heuristic
  const touchOnly = 'ontouchstart' in window && !window.matchMedia('(pointer: fine)').matches;
  if (touchOnly) score -= 1;

  // Try reading WebGL renderer for GPU hints
  try {
    const canvas = document.createElement('canvas');
    const gl = canvas.getContext('webgl') || canvas.getContext('webgl2');
    if (gl) {
      const debugExt = gl.getExtension('WEBGL_debug_renderer_info');
      if (debugExt) {
        const renderer = gl.getParameter(debugExt.UNMASKED_RENDERER_WEBGL).toLowerCase();
        // Known low-end GPU strings
        if (renderer.includes('swiftshader') || renderer.includes('llvmpipe') || renderer.includes('software')) {
          score -= 3; // software renderer
        }
        if (renderer.includes('apple gpu') || renderer.includes('apple m')) {
          score += 2; // Apple Silicon is good
        }
      }
      gl.getExtension('WEBGL_lose_context')?.loseContext();
    }
  } catch {
    // Can't probe GPU, use other signals
  }

  // Map score to tier
  if (score <= 1) cachedTier = 'low';
  else if (score <= 4) cachedTier = 'medium';
  else cachedTier = 'high';

  console.info(`[Matrix Quality] Tier: ${cachedTier} (score: ${score}, cores: ${cores}, mem: ${mem}GB, dpr: ${dpr}, touch: ${touchOnly})`);

  return cachedTier;
}

/**
 * Get the recommended pixel ratio cap for the renderer.
 */
export function getMaxPixelRatio() {
  const tier = getQualityTier();
  if (tier === 'low') return 1;
  if (tier === 'medium') return 1.5;
  return 2;
}