/**
 * Table of Contents (TOC) - Matrix Terminal Style
 * A sticky sidebar navigation for blog articles
 */

/* ===== TOC VARIABLES ===== */
.toc {
  --toc-bg: #0d0d0d;
  --toc-border: #1a1a1a;
  --toc-text: #888888;
  --toc-text-hover: #e0e0e0;
  --toc-accent: #00ff41;
  --toc-accent-dim: #00aa2a;
  --toc-accent-dark: #004010;
  --toc-glow: 0 0 20px rgba(0, 255, 65, 0.3);
  --toc-glow-strong: 0 0 30px rgba(0, 255, 65, 0.5);
  --toc-width: 220px;
  --toc-offset: 120px;
}

/* ===== TOC CONTAINER ===== */
.toc {
  position: fixed;
  top: var(--toc-offset);
  right: calc((100vw - 1000px) / 2 - var(--toc-width) - 40px);
  width: var(--toc-width);
  max-height: calc(100vh - var(--toc-offset) - 40px);
  background: var(--toc-bg);
  border: 1px solid var(--toc-border);
  border-radius: 8px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  overflow: hidden;
  z-index: 100;

  /* Subtle scanline effect */
  background-image:
    linear-gradient(
      transparent 50%,
      rgba(0, 0, 0, 0.05) 50%
    );
  background-size: 100% 4px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

/* Glow border on hover */
.toc:hover {
  border-color: var(--toc-accent-dark);
  box-shadow: var(--toc-glow);
}

/* ===== TOC HEADER ===== */
.toc-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 0.8rem;
  border-bottom: 1px solid var(--toc-border);
  background: rgba(0, 255, 65, 0.03);
}

.toc-comment {
  color: var(--toc-accent-dim);
  font-size: 0.6rem;
  letter-spacing: 0.03em;
  opacity: 0.9;
}

/* Toggle button for collapse */
.toc-toggle {
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.2s ease;
}

.toc-toggle-icon {
  width: 10px;
  height: 10px;
  border: 1px solid var(--toc-accent-dim);
  border-radius: 2px;
  position: relative;
  transition: all 0.2s ease;
}

.toc-toggle-icon::before,
.toc-toggle-icon::after {
  content: '';
  position: absolute;
  background: var(--toc-accent);
  transition: all 0.2s ease;
}

.toc-toggle-icon::before {
  width: 5px;
  height: 1px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.toc-toggle-icon::after {
  width: 1px;
  height: 5px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

.toc-toggle[aria-expanded="true"] .toc-toggle-icon::after {
  transform: translate(-50%, -50%) scaleY(0);
}

.toc-toggle:hover .toc-toggle-icon {
  border-color: var(--toc-accent);
  box-shadow: var(--toc-glow);
}

.toc-toggle:focus-visible {
  outline: 2px solid var(--toc-accent);
  outline-offset: 2px;
  border-radius: 2px;
}

/* ===== TOC LIST ===== */
.toc-list {
  list-style: none;
  margin: 0;
  padding: 0.4rem 0;
  max-height: 55vh;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--toc-accent-dark) transparent;
}

.toc-list::-webkit-scrollbar {
  width: 3px;
}

.toc-list::-webkit-scrollbar-track {
  background: transparent;
}

.toc-list::-webkit-scrollbar-thumb {
  background: var(--toc-accent-dark);
  border-radius: 2px;
}

/* Collapse animation */
.toc.collapsed .toc-list {
  max-height: 0;
  padding: 0;
  overflow: hidden;
}

.toc.collapsed .toc-progress {
  display: none;
}

/* ===== TOC ITEMS ===== */
.toc-item {
  position: relative;
}

.toc-item a {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.8rem;
  color: var(--toc-text);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: all 0.15s ease;
  position: relative;
}

/* Hierarchy indentation */
.toc-h2 a {
  padding-left: 0.8rem;
}

.toc-h3 a {
  padding-left: 1.4rem;
  font-size: 0.65rem;
}

.toc-h4 a {
  padding-left: 2rem;
  font-size: 0.6rem;
}

/* Prefix styling */
.toc-prefix {
  color: var(--toc-accent-dim);
  font-weight: 600;
  min-width: 1ch;
  opacity: 0.5;
  transition: opacity 0.15s ease, color 0.15s ease;
}

/* Text truncation */
.toc-text {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
}

/* Cursor element */
.toc-cursor {
  width: 6px;
  height: 12px;
  background: var(--toc-accent);
  margin-left: auto;
  flex-shrink: 0;
  opacity: 0;
}

/* ===== HOVER STATE ===== */
.toc-item a:hover {
  color: var(--toc-text-hover);
  background: rgba(0, 255, 65, 0.05);
  border-left-color: var(--toc-accent-dim);
}

.toc-item a:hover .toc-prefix {
  opacity: 1;
  color: var(--toc-accent);
}

/* ===== ACTIVE STATE ===== */
.toc-item.active a {
  color: var(--toc-accent);
  border-left-color: var(--toc-accent);
  background: rgba(0, 255, 65, 0.08);
  text-shadow: var(--toc-glow);
}

.toc-item.active .toc-prefix {
  opacity: 1;
  color: var(--toc-accent);
}

/* Blinking cursor for active item */
.toc-item.active .toc-cursor {
  opacity: 1;
  animation: toc-blink 1s step-end infinite;
}

@keyframes toc-blink {
  0%, 50% { opacity: 1; }
  51%, 100% { opacity: 0; }
}

/* ===== PROGRESS BAR ===== */
.toc-progress {
  height: 2px;
  background: var(--toc-border);
  position: relative;
  overflow: hidden;
}

.toc-progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--toc-accent-dim), var(--toc-accent));
  box-shadow: var(--toc-glow);
  transition: width 0.1s ease;
}

/* ===== FOCUS STATES (A11y) ===== */
.toc-item a:focus-visible {
  outline: 2px solid var(--toc-accent);
  outline-offset: -2px;
  background: rgba(0, 255, 65, 0.1);
}

/* ===== RESPONSIVE: HIDE ON SMALLER SCREENS ===== */
@media (max-width: 1300px) {
  .toc {
    right: 20px;
  }
}

@media (max-width: 1100px) {
  .toc {
    display: none;
  }
}

/* ===== MOBILE TOC BUTTON ===== */
.toc-mobile-trigger {
  display: none;
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: 44px;
  height: 44px;
  background: var(--toc-bg);
  border: 1px solid var(--toc-accent-dim);
  border-radius: 50%;
  color: var(--toc-accent);
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.1rem;
  cursor: pointer;
  z-index: 99;
  transition: all 0.2s ease;
  align-items: center;
  justify-content: center;
}

.toc-mobile-trigger:hover {
  border-color: var(--toc-accent);
  box-shadow: var(--toc-glow-strong);
  transform: scale(1.05);
}

.toc-mobile-trigger:focus-visible {
  outline: 2px solid var(--toc-accent);
  outline-offset: 2px;
}

@media (max-width: 1100px) {
  .toc-mobile-trigger {
    display: flex;
  }

  /* Mobile TOC modal */
  .toc.mobile-open {
    display: block;
    position: fixed;
    top: 50%;
    left: 50%;
    right: auto;
    transform: translate(-50%, -50%);
    width: calc(100vw - 40px);
    max-width: 360px;
    max-height: 70vh;
    animation: toc-modal-in 0.2s ease;
  }

  .toc.mobile-open .toc-list {
    max-height: 50vh;
  }

  @keyframes toc-modal-in {
    from {
      opacity: 0;
      transform: translate(-50%, -50%) scale(0.95);
    }
    to {
      opacity: 1;
      transform: translate(-50%, -50%) scale(1);
    }
  }

  /* Backdrop */
  .toc-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(4px);
    z-index: 98;
  }

  .toc-backdrop.visible {
    display: block;
    animation: toc-fade-in 0.2s ease;
  }

  @keyframes toc-fade-in {
    from { opacity: 0; }
    to { opacity: 1; }
  }
}

/* ===== ENTRANCE ANIMATION ===== */
.toc {
  animation: toc-enter 0.4s ease 0.3s both;
}

@keyframes toc-enter {
  from {
    opacity: 0;
    transform: translateX(20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* Staggered item reveal */
.toc-item {
  opacity: 0;
  animation: toc-item-enter 0.25s ease both;
}

.toc-item:nth-child(1) { animation-delay: 0.4s; }
.toc-item:nth-child(2) { animation-delay: 0.45s; }
.toc-item:nth-child(3) { animation-delay: 0.5s; }
.toc-item:nth-child(4) { animation-delay: 0.55s; }
.toc-item:nth-child(5) { animation-delay: 0.6s; }
.toc-item:nth-child(6) { animation-delay: 0.65s; }
.toc-item:nth-child(7) { animation-delay: 0.7s; }
.toc-item:nth-child(8) { animation-delay: 0.75s; }
.toc-item:nth-child(9) { animation-delay: 0.8s; }
.toc-item:nth-child(10) { animation-delay: 0.85s; }
.toc-item:nth-child(n+11) { animation-delay: 0.9s; }

@keyframes toc-item-enter {
  from {
    opacity: 0;
    transform: translateX(10px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  .toc,
  .toc-item,
  .toc-cursor {
    animation: none;
    opacity: 1;
    transform: none;
  }

  .toc-item.active .toc-cursor {
    animation: none;
    opacity: 1;
  }
}