/*
 * The knowledge graph page: the SVG canvas, the list for screen readers, the topic panel and the bottom sheet.
 * Selectors are data-* attributes and elements only; colors come from tokens.css.
 * Rationale: see DESIGN.md.
 *
 * A topic is open in one of two ways. With graph.js the script sets data-current on it (and
 * data-js on the canvas, which turns the fragment off as a selector: after pushState the fragment
 * no longer matches :target, so a stale :target must not open a topic). Without script the
 * fragment decides, through :target alone.
 */

/* The canvas is at its natural size and scrolls in both directions by itself: sideways in its box,
   down the page. */
[data-graph] {
  position: relative;
  display: block;
}

[data-canvas-wrap] {
  display: block;
  max-inline-size: 100%;
  overflow: auto;
}

/* With script, a touch drag pans and a pinch zooms the canvas (graph.js), so the browser must not
   pan or zoom under the finger. Without script the canvas scrolls natively and does not zoom. */
[data-graph][data-js] [data-canvas-wrap] {
  touch-action: none;
}

/* A topic shows only when it is open. */
article[data-node] {
  display: none;
}

article[data-node][data-current],
[data-graph]:not([data-js]) article[data-node]:target {
  display: block;
}

/* Below 780 px the open topic is a bottom sheet over the list. */
[data-panel]:has(article[data-node][data-current]),
[data-graph]:not([data-js]) [data-panel]:has(article[data-node]:target) {
  position: fixed;
  inset-inline: 0;
  inset-block-end: 0;
  z-index: 1;
  max-block-size: 60vh;
  overflow-y: auto;
  padding: 1rem;
  background-color: var(--color-surface);
  border-block-start: 1px solid var(--color-border);
}

[data-graph][data-js] [data-panel]:not(:has(article[data-node][data-current])),
[data-graph]:not([data-js]) [data-panel]:not(:has(article[data-node]:target)) {
  display: none;
}

/* The list of topics is for screen readers only, with or without script: the canvas links and the
   panel reach the same topics for everyone else. */
[data-list] {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

[data-canvas] {
  display: block;
}

[data-canvas] text {
  fill: var(--color-text);
  font-family: var(--font-text);
  font-size: 0.875rem;
}

/* Edges: strong is solid, weak is dashed, so the two differ by shape as well as by color. */
[data-edge] {
  fill: none;
  stroke-width: 2;
}

[data-edge="strong"] {
  stroke: var(--color-dep-strong);
}

[data-edge="weak"] {
  stroke: var(--color-dep-weak);
  stroke-dasharray: 6 4;
}

[data-arrow="strong"] {
  fill: var(--color-dep-strong);
}

[data-arrow="weak"] {
  fill: var(--color-dep-weak);
}

/* Topics: a thin dashed border when the topic has no refs yet. */
[data-node-box] {
  fill: var(--color-surface);
  stroke: var(--color-border-strong);
  stroke-width: 1.5;
}

[data-node-box][data-refs="no"] {
  stroke-width: 1;
  stroke-dasharray: 4 3;
}

/* The study trail of the open topic: its boxes in accent, with a badge that gives the order. */
[data-node-link][data-trail] [data-node-box] {
  stroke: var(--color-accent);
  stroke-width: 3;
}

[data-trail-badge="dot"] {
  fill: var(--color-accent);
}

[data-trail-badge="label"] {
  fill: var(--color-on-accent);
  font-family: var(--font-text);
  font-size: 0.75rem;
  font-weight: 700;
}

/* The trail filter: a native fieldset in the panel. Script shows it, only when the open topic has a trail. */
[data-trail-filter] {
  margin: 0 0 1rem;
  padding: 0;
  border: 0;
  font-size: 0.875rem;
}

[data-trail-filter] legend {
  padding: 0;
  margin-block-end: 0.25rem;
  font-weight: 700;
}

[data-trail-filter] label {
  margin-inline-end: 1rem;
}

[data-node-link] {
  cursor: pointer;
}

[data-node-link]:hover [data-node-box] {
  stroke: var(--color-link-hover);
}

[data-node-link]:focus-visible [data-node-box] {
  stroke: var(--color-focus);
  stroke-width: 3;
}

@media (min-width: 780px) {
  [data-page="graph"] {
    max-inline-size: 90rem;
  }

  /* The canvas is the main view, with the panel beside it when a topic is open. */
  [data-graph] {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    align-items: start;
    gap: 2rem;
  }

  [data-graph]:has(article[data-node][data-current]),
  [data-graph]:not([data-js]):has(article[data-node]:target) {
    grid-template-columns: minmax(0, 1fr) minmax(18rem, 26rem);
  }

  [data-panel]:has(article[data-node][data-current]),
  [data-graph]:not([data-js]) [data-panel]:has(article[data-node]:target) {
    position: sticky;
    inset: auto auto auto auto;
    inset-block-start: 0;
    max-block-size: 100vh;
    padding: 0 0 0 1.5rem;
    border-block-start: 0;
    border-inline-start: 1px solid var(--color-border);
  }
}

@media (prefers-reduced-motion: no-preference) {
  [data-node-box] {
    transition: stroke 150ms ease-out, stroke-width 150ms ease-out;
  }

  [data-panel] article[data-node][data-current],
  [data-graph]:not([data-js]) [data-panel] article[data-node]:target {
    animation: graph-topic-in 200ms ease-out;
  }
}

@keyframes graph-topic-in {
  from {
    opacity: 0;
    transform: translateY(0.5rem);
  }

  to {
    opacity: 1;
    transform: none;
  }
}