Region splice

/**
 * MIT License
 * Copyright (c) 2026 Subframe
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
"use client"
import * as React from "react"

type Region = { id: string; name: string; start: number; end: number }
type Mode = "move" | "start" | "end"
const INITIAL: Region[] = [
  { id: "intro", name: "Intro", start: 1, end: 6 },
  { id: "answer", name: "Answer", start: 8, end: 14 },
  { id: "outro", name: "Outro", start: 17, end: 23 },
]
const LENGTH = 24
const MINIMUM = 4
const GAP = 0.25
const clamp = (value: number, min: number, max: number) => Math.max(min, Math.min(max, value))
const PEAKS = Array.from(
  { length: 216 },
  (_, i) => 4 + 41 * Math.abs(Math.sin(i * 1.93) * Math.cos(i * 0.19)) * (0.25 + 0.75 * Math.abs(Math.sin(i * 0.075))),
)

function shiftRegion(regions: Region[], index: number, mode: Mode, amount: number) {
  const region = regions[index]
  const left = index ? regions[index - 1].end + GAP : 0
  const right = index < regions.length - 1 ? regions[index + 1].start - GAP : LENGTH
  let { start, end } = region
  if (mode === "move") {
    const delta = clamp(amount, left - start, right - end)
    start += delta
    end += delta
  }
  if (mode === "start") start = clamp(start + amount, left, end - MINIMUM)
  if (mode === "end") end = clamp(end + amount, start + MINIMUM, right)
  return regions.map((item, i) => (i === index ? { ...item, start, end } : item))
}

export default function Example({ active = true }: { active?: boolean }) {
  const [regions, setRegions] = React.useState(INITIAL)
  const [selected, setSelected] = React.useState(1)
  const [snap, setSnap] = React.useState(true)
  const [dragging, setDragging] = React.useState(false)
  const track = React.useRef<HTMLDivElement>(null)
  const drag = React.useRef<{ pointer: number; x: number; index: number; mode: Mode; before: Region[] } | null>(null)
  const region = regions[selected]
  function start(event: React.PointerEvent<HTMLButtonElement>, index: number, mode: Mode) {
    if (!active || event.button !== 0 || drag.current) return
    event.preventDefault()
    event.currentTarget.focus({ preventScroll: true })
    event.currentTarget.setPointerCapture(event.pointerId)
    drag.current = { pointer: event.pointerId, x: event.clientX, index, mode, before: regions }
    setSelected(index)
    setDragging(true)
  }
  function move(event: React.PointerEvent<HTMLButtonElement>) {
    const current = drag.current
    if (!active || !current || current.pointer !== event.pointerId || !track.current) return
    const width = track.current.getBoundingClientRect().width
    if (!width) return
    let amount = ((event.clientX - current.x) / width) * LENGTH
    if (snap) {
      const anchor = current.before[current.index][current.mode === "end" ? "end" : "start"]
      amount = Math.round((anchor + amount) * 4) / 4 - anchor
    }
    setRegions(shiftRegion(current.before, current.index, current.mode, amount))
  }
  function end(cancel = false) {
    if (cancel && drag.current) setRegions(drag.current.before)
    drag.current = null
    setDragging(false)
  }
  function key(event: React.KeyboardEvent<HTMLButtonElement>, index: number, mode: Mode) {
    if (!active) return
    if (event.key === "Escape") {
      end(true)
      return
    }
    if (!["ArrowLeft", "ArrowRight", "Home", "End"].includes(event.key)) return
    event.preventDefault()
    setSelected(index)
    const amount =
      event.key === "Home"
        ? -LENGTH
        : event.key === "End"
        ? LENGTH
        : (event.key === "ArrowLeft" ? -1 : 1) * (event.shiftKey ? 1 : 0.25)
    setRegions((current) => shiftRegion(current, index, mode, amount))
  }
  React.useEffect(() => {
    if (!active) {
      drag.current = null
      setDragging(false)
    }
  }, [active])
  const handlers = (index: number, mode: Mode) => ({
    onPointerDown: (event: React.PointerEvent<HTMLButtonElement>) => start(event, index, mode),
    onPointerMove: move,
    onPointerUp: () => end(),
    onPointerCancel: () => end(true),
    onLostPointerCapture: () => end(),
    onKeyDown: (event: React.KeyboardEvent<HTMLButtonElement>) => key(event, index, mode),
  })
  return (
    <div className="sf-region-splice" data-dragging={dragging}>
      <section className="editor" aria-label="Dialogue region editor">
        <header>
          <span>
            <i aria-hidden="true" />
            Dialogue <small>take 04</small>
          </span>
          <div>
            <button className="snap" disabled={!active} aria-pressed={snap} onClick={() => setSnap(!snap)}>
              Snap <span>¼ s</span>
            </button>
            <button
              className="reset"
              disabled={!active}
              aria-label="Reset regions"
              onClick={() => {
                end()
                setRegions(INITIAL)
                setSelected(1)
              }}
            >
              ↺
            </button>
          </div>
        </header>
        <div className="timeline">
          <div className="ruler" aria-hidden="true">
            {[0, 4, 8, 12, 16, 20, 24].map((time) => (
              <span key={time}>{String(time).padStart(2, "0")}</span>
            ))}
          </div>
          <div className="track" ref={track}>
            <div className="bed" aria-hidden="true">
              <svg viewBox="0 0 648 100" preserveAspectRatio="none">
                {PEAKS.map((height, index) => (
                  <path key={index} d={`M${index * 3 + 1} ${50 - height / 2}v${height}`} />
                ))}
              </svg>
            </div>
            {regions.map((item, index) => (
              <div
                className="region"
                key={item.id}
                data-selected={selected === index}
                style={{
                  left: (item.start / LENGTH) * 100 + "%",
                  width: ((item.end - item.start) / LENGTH) * 100 + "%",
                }}
              >
                <button
                  className="move"
                  disabled={!active}
                  aria-label={`Move ${item.name} region`}
                  aria-pressed={selected === index}
                  onClick={() => setSelected(index)}
                  {...handlers(index, "move")}
                >
                  <span>{item.name}</span>
                </button>
                <svg
                  className="region-wave"
                  viewBox={`${(item.start / LENGTH) * 648} 0 ${((item.end - item.start) / LENGTH) * 648} 100`}
                  preserveAspectRatio="none"
                  aria-hidden="true"
                >
                  {PEAKS.map((height, i) => (
                    <path key={i} d={`M${i * 3 + 1} ${50 - height / 2}v${height}`} />
                  ))}
                </svg>
                {selected === index &&
                  (["start", "end"] as const).map((edge) => (
                    <button
                      key={edge}
                      className="edge"
                      data-edge={edge}
                      role="slider"
                      disabled={!active}
                      aria-label={`${item.name} ${edge}`}
                      aria-valuemin={
                        edge === "start" ? (index ? regions[index - 1].end + GAP : 0) : item.start + MINIMUM
                      }
                      aria-valuemax={
                        edge === "end"
                          ? index < regions.length - 1
                            ? regions[index + 1].start - GAP
                            : LENGTH
                          : item.end - MINIMUM
                      }
                      aria-valuenow={Number(item[edge].toFixed(2))}
                      aria-valuetext={`${item[edge].toFixed(2)} seconds`}
                      {...handlers(index, edge)}
                    >
                      <i aria-hidden="true" />
                    </button>
                  ))}
              </div>
            ))}
          </div>
        </div>
        <footer>
          <strong>{region.name}</strong>
          <div>
            <span>
              In <output>{region.start.toFixed(2)}</output>
            </span>
            <span>
              Out <output>{region.end.toFixed(2)}</output>
            </span>
            <span className="duration">
              <output>{(region.end - region.start).toFixed(2)}</output> s
            </span>
          </div>
        </footer>
      </section>
      <style>{`
.sf-region-splice{width:100%;height:100%;display:grid;place-items:center;padding:26px;box-sizing:border-box;background:#311d2c;color:#eae0e8;font:12px/1.4 -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;overflow:hidden;container-type:inline-size}.sf-region-splice *{box-sizing:border-box}.sf-region-splice button{font:inherit;color:inherit;cursor:pointer;touch-action:manipulation}.sf-region-splice button:disabled{cursor:default}.sf-region-splice :focus-visible{outline:2px solid #e9bbe0;outline-offset:3px}.sf-region-splice .editor{width:min(100%,540px);border:1px solid #ffffff13;background:#412a3c;border-radius:12px;box-shadow:0 18px 50px #13071640;overflow:hidden}.sf-region-splice header{height:65px;padding:0 20px;display:flex;align-items:center;justify-content:space-between;gap:12px;border-bottom:1px solid #ffffff0b}.sf-region-splice header>span{display:flex;align-items:center;gap:9px;font-weight:500;white-space:nowrap}.sf-region-splice header i{width:7px;height:7px;border-radius:50%;background:#d7a1c9}.sf-region-splice header small{color:#ac8fa6;font-size:10px;font-weight:400;margin-left:3px}.sf-region-splice header>div{display:flex;align-items:center;gap:10px}.sf-region-splice .snap{height:32px;padding:0 9px;border:1px solid #ffffff12;border-radius:5px;font-size:10px;background:transparent;color:#b99db1}.sf-region-splice .snap[aria-pressed=true]{background:#63445b;color:#f0dbeb}.sf-region-splice .snap span{margin-left:5px;font:9px ui-monospace,monospace;opacity:.7}.sf-region-splice .reset{background:transparent;border:0;width:28px;height:44px;font-size:19px;color:#c2a7ba}.sf-region-splice .timeline{padding:19px 22px 23px}.sf-region-splice .ruler{display:flex;justify-content:space-between;font:9px ui-monospace,monospace;color:#a38a9a;margin-bottom:13px}.sf-region-splice .ruler span{position:relative}.sf-region-splice .ruler span:after{content:"";position:absolute;top:16px;left:0;width:1px;height:4px;background:#9c7e9260}.sf-region-splice .track{position:relative;height:116px;background:#2d1d2b;border:1px solid #ffffff06;border-radius:5px}.sf-region-splice .bed{position:absolute;inset:28px 0 0;opacity:.28;overflow:hidden}.sf-region-splice .bed svg{width:100%;height:100%}.sf-region-splice svg path{stroke:#c69bb9;stroke-width:1.6;stroke-linecap:round}.sf-region-splice .region{position:absolute;top:0;bottom:0;background:#724f6845;border:1px solid #a1759344;border-radius:5px;min-width:0;transition:background-color 130ms ease,border-color 130ms ease}.sf-region-splice .region[data-selected=true]{background:#9c688659;border-color:#d7a0c0;box-shadow:0 0 0 1px #d7a0c012}.sf-region-splice .move{position:absolute;inset:0;border:0;background:transparent;width:100%;padding:0;touch-action:none;cursor:grab;z-index:1;text-align:left}.sf-region-splice .move>span{position:absolute;top:7px;left:9px;right:4px;font-size:9px;color:#d9bdd0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.sf-region-splice .region[data-selected=true] .move>span{color:#fff1fa}.sf-region-splice .region-wave{position:absolute;top:28px;bottom:0;left:0;width:100%;height:calc(100% - 28px);pointer-events:none;overflow:hidden}.sf-region-splice .region-wave path{stroke:#b891aa}.sf-region-splice .region[data-selected=true] .region-wave path{stroke:#edc6df}.sf-region-splice .edge{position:absolute;top:30px;bottom:0;width:30px;background:transparent;border:0;z-index:2;touch-action:none;cursor:ew-resize;padding:0}.sf-region-splice .edge[data-edge=start]{left:-15px}.sf-region-splice .edge[data-edge=end]{right:-15px}.sf-region-splice .edge i{position:absolute;left:12px;top:31px;width:5px;height:20px;background:#f4d5e9;border:1px solid #ae7898;border-radius:3px;box-shadow:0 1px 4px #0002}.sf-region-splice[data-dragging=true] .move{cursor:grabbing}.sf-region-splice footer{height:48px;border-top:1px solid #ffffff0b;padding:0 20px;display:flex;align-items:center;justify-content:space-between;gap:10px;background:#3b2636}.sf-region-splice footer>strong{font-weight:500;font-size:10px;color:#d9bbce}.sf-region-splice footer>div{display:flex;gap:15px;font-size:9px;color:#9f8296;align-items:center}.sf-region-splice footer output{font:10px ui-monospace,monospace;font-variant-numeric:tabular-nums;color:#e3c9da;margin-left:5px}.sf-region-splice .duration{padding-left:13px;border-left:1px solid #ffffff15}.sf-region-splice .duration output{margin:0}.sf-region-splice button:active:not(.move):not(.edge){transform:scale(.98)}@media(prefers-reduced-motion:reduce){.sf-region-splice *{transition:none!important}}@container(max-width:390px){.sf-region-splice header{padding-inline:15px}.sf-region-splice header small{display:none}.sf-region-splice .timeline{padding-inline:16px}.sf-region-splice footer{padding-inline:15px}.sf-region-splice footer>div{gap:9px}.sf-region-splice .duration{padding-left:8px}}
`}</style>
    </div>
  )
}