/*
 * The alternatives side panel (issue #10, spec R-4.1 to R-4.4, section 10)
 * ========================================================================
 *
 * Consumes the design tokens from tokens.css; the panel adds only its own
 * geometry and the dim level of the text behind it, defined once here:
 *
 *   --te-alt-panel-width   18% of the window, as measured in the demo video
 *                          (R-4.1; docs/requirements/video-measurements.md):
 *                          about 205px at a 1140px window
 *   --te-alt-dim-opacity   the main text while the panel is open (R-4.1)
 *
 * The DOM is built by public/js/alternatives-panel.js. The panel is fixed to
 * the left edge; on windows wide enough, the writing column moves right so
 * the panel never covers it, and it stays centred when there is room.
 */

/*
 * The 12rem floor keeps the three cursive tabs and the alternative lines
 * legible; it takes over below a 1067px window (12rem is 18% of 1067px), so
 * every window from there up gets the measured 18%. The 20rem cap stops the
 * panel growing past what a list of single words needs on very wide
 * screens; it is reached at 1778px. Below 48rem the narrow-screen rule at
 * the end of this file replaces the width with an overlay.
 */
:root {
    --te-alt-panel-width: clamp(12rem, 18vw, 20rem);
    --te-alt-dim-opacity: 0.7;
}

.te-alt-panel[hidden] {
    display: none !important;
}

.te-alt-panel {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 20;
    box-sizing: border-box;
    width: var(--te-alt-panel-width);
    display: flex;
    flex-direction: column;
    /* As in the video at 1:15 to 1:35: the tabs sit just above the level of
       the document's first line (the page's top margin), and the key hint at
       the foot, clear of the bottom-left corner controls (1.25rem offset plus
       a 1.75rem control, and air), as on the Overflow panel. */
    padding: max(1.5rem, calc(var(--te-page-margin-top) - 2.5rem)) 1.25rem 4.25rem;
    container-type: inline-size;
    background-color: var(--te-color-panel);
    border-right: 1px solid var(--te-color-panel-border);
    color: var(--te-color-text);
    font-family: var(--te-font-mono);
    font-size: 0.9375rem;
    line-height: var(--te-line-height);
    color-scheme: dark;
    overflow-y: auto;
}

/* ---- Tabs (R-4.2): cursive, active lavender, the others cream ---- */

/* One line, as in the video (Word · Sentence · Paragraph is 70% of the
   panel's width there). The display face is a stack, not a web font, so the
   size follows the panel's content width (7cqi): the widest common fallback,
   Bradley Hand Bold, still fits at the 12rem floor, and the size stops at
   1.3125rem on wide panels. */
.te-alt-tabs {
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
    flex-wrap: nowrap;
    white-space: nowrap;
    margin-bottom: 1.25rem;
}

.te-alt-tab {
    margin: 0;
    padding: 0 0.125rem;
    border: 0;
    border-radius: 4px;
    background: none;
    color: var(--te-color-text);
    font-family: var(--te-font-display);
    font-size: min(1.3125rem, 7cqi);
    line-height: 1.2;
    cursor: pointer;
}

.te-alt-tab:hover {
    color: var(--te-color-accent);
}

.te-alt-tab.te-alt-tab--active,
.te-alt-tab[aria-selected="true"] {
    color: var(--te-color-accent);
}

.te-alt-tab:focus-visible,
.te-alt-delete:focus-visible {
    outline: 2px solid var(--te-color-accent);
    outline-offset: 2px;
}

/* ---- Status and hint ---- */

.te-alt-status {
    margin: 0 0 0.75rem;
    color: var(--te-color-text-dim);
    font-size: 0.8125rem;
}

/* The routine count ("Word: 5 alternatives, …") is announced but not shown:
   the video has no status line. */
.te-alt-status.te-alt-status--quiet {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0 0 0 0);
    clip-path: inset(50%);
    white-space: nowrap;
    border: 0;
}

/* The tab panel fills the rest of the height so the hint can sit at its
   foot. */
.te-alt-tabpanel {
    display: flex;
    flex: 1 1 auto;
    flex-direction: column;
    min-height: 0;
}

.te-alt-hint {
    margin: auto 0 0;
    padding-top: 1rem;
    color: var(--te-color-text-dim);
    font-size: 0.75rem;
}

/* ---- Lines (R-4.3, R-4.4) ---- */

.te-alt-list {
    margin: 0;
    padding: 0;
    list-style: none;
}

.te-alt-list[hidden] {
    display: none;
}

.te-alt-line {
    display: grid;
    grid-template-columns: 1.25rem 1fr auto;
    align-items: center;
    column-gap: 0.25rem;
    border-radius: 4px;
}

.te-alt-glyph {
    justify-self: center;
    color: var(--te-color-text-dim);
}

/* The author's dot is small ("bullet point"); the robot is a touch larger. */
.te-alt-glyph--human {
    font-size: 0.3125rem;
}

.te-alt-glyph--ai {
    font-size: 0.75rem;
}

.te-alt-glyph--new {
    font-size: 0.625rem;
    opacity: 0.6;
}

.te-alt-input {
    box-sizing: border-box;
    width: 100%;
    min-width: 0;
    margin: 0;
    padding: 0.125rem 0.25rem;
    border: 0;
    border-bottom: 1px solid transparent;
    background: transparent;
    /* Inactive lines sit back; the active one is brighter (R-4.4). */
    color: var(--te-color-text-dim);
    font: inherit;
    caret-color: var(--te-color-accent);
}

.te-alt-input:focus {
    outline: none;
    border-bottom-color: var(--te-color-accent-soft);
}

.te-alt-input:focus-visible {
    border-bottom-color: var(--te-color-accent);
}

.te-alt-input[readonly] {
    cursor: default;
}

.te-alt-input::placeholder {
    color: var(--te-color-text-dim);
    opacity: 0.7;
}

.te-alt-line--active .te-alt-input {
    color: var(--te-color-text);
    font-weight: 700;
}

.te-alt-line--active .te-alt-glyph {
    color: var(--te-color-accent);
}

.te-alt-line:hover:not(.te-alt-line--new) {
    background-color: var(--te-color-popover-hover);
}

.te-alt-delete {
    margin: 0;
    padding: 0 0.375rem;
    border: 0;
    border-radius: 4px;
    background: none;
    color: var(--te-color-text-dim);
    font-size: 0.75rem;
    cursor: pointer;
    visibility: hidden;
}

.te-alt-line:hover .te-alt-delete,
.te-alt-line:focus-within .te-alt-delete {
    visibility: visible;
}

.te-alt-delete:hover {
    color: var(--te-color-text);
}

/* ---- The writing surface while the panel is open (R-4.1) ---- */

.te-alt-open .markdown-input.te-surface {
    opacity: var(--te-alt-dim-opacity);
    transition: opacity 160ms ease-out;
}

@media (min-width: 48rem) {
    .te-app[data-mode="write-on"].te-alt-open .markdown-input.te-surface {
        margin-left: max(
            calc(var(--te-alt-panel-width) + 1rem),
            calc((100% - var(--te-measure) - 3rem) / 2)
        );
        margin-right: auto;
    }
}

@media (max-width: 47.99rem) {
    .te-alt-panel {
        width: min(100vw, 22rem);
    }
}

@media (prefers-reduced-motion: reduce) {
    .te-alt-open .markdown-input.te-surface {
        transition: none;
    }
}