/**
 * Liquid glass: the readings.
 *
 * Lit fills over translucent tracks, and every number written out beside the
 * picture it is drawn as — an angle or a length nobody can measure is not a
 * reading.
 */
import { motion, useTransform } from "motion/react"

import { cn } from "@/lib/utils"
import { arcPath, GAUGE_START, GAUGE_SWEEP, GAUGE_TRACK } from "../core/arc"
import { cssOf } from "../core/color"
import { format } from "../core/config"
import type {
  BarProps,
  ColorDiskProps,
  GaugeProps,
  ReadoutProps,
} from "../core/contract"
import { TESTID } from "../core/contract"
import { useColorDisk } from "../core/disc"
import { useAnimatedFraction, useAnimatedNumber } from "../core/values"
import { Slider } from "./Controls"

export function Readout({
  value,
  precision,
  unit,
  size = "hero",
}: ReadoutProps) {
  const { label, numeric } = useAnimatedNumber(value, precision)
  return (
    <span data-testid="readout" className="flex min-w-0 items-baseline gap-1.5">
      <span
        className={cn(
          "min-w-0 truncate",
          size === "hero" ? "dui-hero" : "tabular-nums",
        )}
      >
        {numeric ? (
          <motion.span>{label}</motion.span>
        ) : (
          format(value, precision)
        )}
      </span>
      {unit ? (
        <span
          className={cn(
            "shrink-0 text-muted-foreground",
            size === "hero" && "dui-hero-unit",
          )}
        >
          {unit}
        </span>
      ) : null}
    </span>
  )
}

export function Gauge({ value, min, max, precision, unit, label }: GaugeProps) {
  const fraction = useAnimatedFraction(
    value === null
      ? 0
      : Math.min(1, Math.max(0, (value - min) / (max - min || 1))),
  )
  const { label: reading, numeric } = useAnimatedNumber(value, precision)
  return (
    <div className="flex min-h-0 flex-1 items-center justify-center">
      <svg
        viewBox="0 0 100 78"
        className="h-full max-h-full w-full"
        role="img"
        aria-label={`${label}: ${format(value, precision)}${unit ?? ""} of ${max}`}
      >
        <path
          d={GAUGE_TRACK}
          fill="none"
          stroke="var(--gl-track)"
          strokeWidth={9}
          strokeLinecap="round"
        />
        {/* The same full arc as the track, revealed rather than re-pathed: `d`
            is not animatable, so a reading that redrew the arc could only
            jump. `pathLength` normalises it, which makes the reveal the
            fraction itself. */}
        <motion.path
          d={arcPath(GAUGE_START, GAUGE_START + GAUGE_SWEEP)}
          // Glass lights what it draws: the arc carries the same glow the
          // fills and the active controls do.
          style={{
            pathLength: fraction,
            filter: "drop-shadow(0 0 4px var(--primary))",
          }}
          fill="none"
          stroke="var(--primary)"
          strokeWidth={9}
          strokeLinecap="round"
        />
        <text
          x={50}
          y={54}
          // User units of the viewBox, not the text scale: the readout has to
          // stay proportional to the dial at whatever size the tile is.
          fontSize={13}
          textAnchor="middle"
          className="fill-foreground tabular-nums"
        >
          {numeric ? (
            <motion.tspan>{reading}</motion.tspan>
          ) : (
            format(value, precision)
          )}
          {unit ?? ""}
        </text>
      </svg>
    </div>
  )
}

function Row({ row }: { row: BarProps["rows"][number] }) {
  const fraction = useAnimatedFraction(row.fraction)
  const width = useTransform(fraction, (at) => `${at * 100}%`)
  return (
    <div
      data-testid={TESTID.barRow}
      role="img"
      aria-label={`${row.label} ${format(row.value, row.precision)}${row.unit ?? ""}`}
      className="dui-bar-row"
      style={{ "--dui-fill": row.color } as React.CSSProperties}
    >
      <span className="dui-bar-label">{row.label}</span>
      <span className="dui-bar-track gl-track">
        <motion.span
          data-testid={TESTID.barFill}
          className="dui-bar-fill gl-fill"
          style={{ width }}
        />
      </span>
      {/* Beside the track rather than on it: a number written on a fill has to
          clear the fill it sits on and the track it slides onto, and one that
          reads across a room cannot do both. */}
      <span className="dui-bar-value">
        {format(row.value, row.precision)}
        {row.unit ?? ""}
      </span>
    </div>
  )
}

export function Bar({ rows }: BarProps) {
  // No group role of its own: each row already announces what it reads and
  // what it is worth, and the tile's title is on the frame around them.
  return (
    <div className="dui-bar">
      {rows.map((row, index) => (
        // Two rows can read the same message under different labels; position
        // is the identity, as it is for chart series.
        <Row key={`row-${index}`} row={row} />
      ))}
    </div>
  )
}

export function ColorDisk({
  name,
  hsv,
  disabled,
  onChange,
  onCommit,
}: ColorDiskProps) {
  const { discProps, thumb, shade } = useColorDisk({
    name,
    hsv,
    disabled,
    onChange,
    onCommit,
  })
  const [hue, saturation, brightness] = hsv
  return (
    <div className="dui-color">
      <div
        {...discProps}
        data-testid={TESTID.disc}
        className="dui-disc"
        style={
          {
            "--dui-shade": shade,
            "--dui-sx": thumb.sx,
            "--dui-sy": thumb.sy,
          } as React.CSSProperties
        }
      >
        <span className="dui-disc-shade" aria-hidden />
        <span
          aria-hidden
          data-testid={TESTID.swatch}
          className="dui-disc-thumb gl-disc-thumb"
          style={{ background: cssOf(hsv) }}
        />
      </div>
      <Slider
        orientation="vertical"
        value={brightness}
        min={0}
        max={100}
        step={1}
        unit="%"
        label={`${name} brightness`}
        disabled={disabled}
        onCommit={(next) => {
          onChange([hue, saturation, next])
          onCommit()
        }}
      />
    </div>
  )
}