Photo Resizer for Official Forms

import PhotoResizer from "./PhotoResizer";

export default function Demo() {
  return <PhotoResizer />;
}

.card {
  --surface: #fcfcfb;
  --ink: #0b0b0b;
  --ink-2: #52514e;
  --muted: #898781;
  --border: rgba(11, 11, 11, 0.1);
  --field: #f4f3f0;
  --accent: #2a78d6;
  --good: #0ca30c;
  --serious: #ec835a;
  --checker: #e8e7e2;

  width: 100%;
  max-width: 580px;
  padding: 22px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 12px 32px -12px rgba(0, 0, 0, 0.18);
  color: var(--ink);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  container-type: inline-size;
}

@media (prefers-color-scheme: dark) {
  .card {
    --surface: #1a1a19;
    --ink: #ffffff;
    --ink-2: #c3c2b7;
    --border: rgba(255, 255, 255, 0.1);
    --field: #232321;
    --accent: #3987e5;
    --checker: #2c2c2a;
    box-shadow: 0 12px 32px -12px rgba(0, 0, 0, 0.6);
  }
}

.head { margin-bottom: 14px; }
.title { margin: 0; font-size: 17px; font-weight: 650; }
.subtitle { margin: 2px 0 0; color: var(--ink-2); font-size: 13px; }

/* Presets */
.presets { display: grid; grid-template-columns: repeat(auto-fill, minmax(122px, 1fr)); gap: 6px; }
.preset {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 1px;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: none;
  color: var(--ink);
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.preset:hover { background: var(--field); }
.preset[aria-checked="true"] {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  box-shadow: inset 0 0 0 1px var(--accent);
}
.preset:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.presetName { font-size: 13px; font-weight: 600; }
.presetDetail { color: var(--ink-2); font-size: 11px; font-variant-numeric: tabular-nums; }

.custom { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin-top: 10px; }
.customField { display: flex; flex-direction: column; gap: 4px; color: var(--ink-2); font-size: 11.5px; }
.customField input {
  height: 34px;
  min-width: 0;
  padding: 0 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  outline: none;
  background: var(--field);
  color: var(--ink);
  font: inherit;
  font-size: 14px;
  font-weight: 600;
}
.customField input:focus { border-color: var(--accent); }

.disclaimer { margin: 8px 0 14px; color: var(--muted); font-size: 11.5px; }

/* Empty state */
.dropzone {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 32px 16px;
  border: 1.5px dashed color-mix(in srgb, var(--ink) 22%, transparent);
  border-radius: 14px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.dropzone:hover,
.dropzone[data-over="true"] { border-color: var(--accent); background: color-mix(in srgb, var(--accent) 6%, transparent); }
.dropzone:focus-within { outline: 2px solid var(--accent); outline-offset: 2px; }
.fileInput { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.dropIcon { fill: none; stroke: var(--accent); stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.dropTitle { font-size: 14px; font-weight: 600; }
.dropNote { color: var(--muted); font-size: 12px; }
.sampleLink {
  margin-top: 6px;
  padding: 0;
  border: 0;
  background: none;
  color: var(--accent);
  font: inherit;
  font-size: 13px;
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}

/* Editor + result */
.body { display: grid; grid-template-columns: auto 1fr; align-items: start; gap: 22px; }
@container (max-width: 500px) {
  .body { grid-template-columns: 1fr; justify-items: center; }
  .output { width: 100%; }
}

.editor { display: flex; flex-direction: column; align-items: center; gap: 10px; }
.frame {
  position: relative;
  overflow: hidden;
  border-radius: 6px;
  background: repeating-conic-gradient(var(--checker) 0 25%, transparent 0 50%) 0 0 / 16px 16px;
  box-shadow: 0 0 0 1px var(--border), 0 6px 20px -8px rgba(0, 0, 0, 0.3);
  cursor: grab;
  touch-action: none;
  user-select: none;
}
.frame:active { cursor: grabbing; }
.frame:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.photo { position: absolute; top: 50%; left: 50%; max-width: none; pointer-events: none; }
.thirds {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(to right, transparent calc(33.33% - 0.5px), rgba(255, 255, 255, 0.45) 0 calc(33.33% + 0.5px), transparent 0 calc(66.66% - 0.5px), rgba(255, 255, 255, 0.45) 0 calc(66.66% + 0.5px), transparent 0),
    linear-gradient(to bottom, transparent calc(33.33% - 0.5px), rgba(255, 255, 255, 0.45) 0 calc(33.33% + 0.5px), transparent 0 calc(66.66% - 0.5px), rgba(255, 255, 255, 0.45) 0 calc(66.66% + 0.5px), transparent 0);
  pointer-events: none;
}
.faceGuide {
  position: absolute;
  top: 14%;
  left: 50%;
  width: 46%;
  height: 58%;
  border: 1.5px dashed rgba(255, 255, 255, 0.85);
  border-radius: 50%;
  box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.15);
  transform: translateX(-50%);
  pointer-events: none;
}

.zoom { display: flex; align-items: center; gap: 10px; width: 100%; max-width: 260px; color: var(--ink-2); font-size: 12px; }
.zoom input { flex: 1; accent-color: var(--accent); }
.hint { margin: 0; color: var(--muted); font-size: 11.5px; }

.output { display: flex; flex-direction: column; gap: 10px; min-width: 0; }
.outputLabel { color: var(--ink-2); font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
.preview {
  width: 100%;
  max-width: 140px;
  max-height: 160px;
  overflow: hidden;
  border-radius: 4px;
  background: var(--field);
  box-shadow: 0 0 0 1px var(--border);
}
.preview img { display: block; width: 100%; height: 100%; object-fit: contain; }

.facts { display: flex; flex-direction: column; gap: 4px; margin: 0; font-size: 13px; }
.facts div { display: flex; justify-content: space-between; gap: 12px; }
.facts dt { color: var(--ink-2); }
.facts dd { margin: 0; font-weight: 600; font-variant-numeric: tabular-nums; text-align: right; }
.limit { color: var(--muted); font-weight: 400; }

.status { display: flex; align-items: center; gap: 8px; margin: 0; font-size: 13px; font-weight: 600; }
.status span {
  display: grid;
  flex: none;
  place-items: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--good);
  color: #fff;
  font-size: 11px;
}
.status[data-ok="false"] span { background: var(--serious); color: #0b0b0b; }

.download {
  display: grid;
  place-items: center;
  height: 40px;
  border-radius: 10px;
  background: var(--ink);
  color: var(--surface);
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  transition: opacity 0.15s ease, transform 0.1s ease;
}
.download:hover { opacity: 0.88; }
.download:active { transform: scale(0.98); }
.download[aria-disabled="true"] { opacity: 0.4; pointer-events: none; }
.download:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.replace {
  padding: 0;
  border: 0;
  background: none;
  color: var(--ink-2);
  font: inherit;
  font-size: 12.5px;
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}

"use client";

import { useEffect, useRef, useState, type DragEvent, type KeyboardEvent, type PointerEvent } from "react";
import { compressToLimit, drawSamplePortrait } from "./image";
import styles from "./PhotoResizer.module.css";

type Size = { w: number; h: number; kb: number | null; guide: boolean };
type Preset = Size & { key: string; label: string };
type Photo = { img: HTMLImageElement; url: string };
type Result = { url: string; bytes: number; quality: number; fits: boolean };

const PRESETS: Preset[] = [
  { key: "job", label: "Job / admission", w: 300, h: 300, kb: 100, guide: true },
  { key: "signature", label: "Signature", w: 300, h: 80, kb: 60, guide: false },
  { key: "passport", label: "Passport size", w: 413, h: 531, kb: null, guide: true },
  { key: "visa", label: "US visa", w: 600, h: 600, kb: 240, guide: true },
];

// Largest the crop frame is drawn on screen.
const FRAME = { w: 260, h: 280 };
const MAX_ZOOM = 4;

const clamp = (v: number, lo: number, hi: number) => Math.max(lo, Math.min(hi, v));
const kb = (bytes: number) => `${Math.round(bytes / 1024)} KB`;

export default function PhotoResizer() {
  const [presetKey, setPresetKey] = useState("job");
  const [custom, setCustom] = useState({ w: "400", h: "400", kb: "150" });
  const [photo, setPhoto] = useState<Photo | null>(null);
  const [zoom, setZoom] = useState(1);
  const [offset, setOffset] = useState({ x: 0, y: 0 });
  const [result, setResult] = useState<Result | null>(null);
  const [dragOver, setDragOver] = useState(false);
  const frameRef = useRef<HTMLDivElement>(null);
  const drag = useRef<{ px: number; py: number; ox: number; oy: number } | null>(null);

  const preset = PRESETS.find((p) => p.key === presetKey);
  const size: Size = preset ?? {
    w: clamp(Math.round(Number(custom.w) || 0), 50, 3000),
    h: clamp(Math.round(Number(custom.h) || 0), 50, 3000),
    kb: Number(custom.kb) > 0 ? Number(custom.kb) : null,
    guide: false,
  };

  // On-screen crop frame with the target aspect ratio.
  const frameScale = Math.min(FRAME.w / size.w, FRAME.h / size.h);
  const frameW = size.w * frameScale;
  const frameH = size.h * frameScale;

  const nw = photo?.img.naturalWidth ?? 1;
  const nh = photo?.img.naturalHeight ?? 1;
  const scale = Math.max(frameW / nw, frameH / nh) * zoom; // screen px per image px
  const dispW = nw * scale;
  const dispH = nh * scale;
  // Keep the photo covering the frame however it is dragged or zoomed.
  const pos = {
    x: clamp(offset.x, -(dispW - frameW) / 2, (dispW - frameW) / 2),
    y: clamp(offset.y, -(dispH - frameH) / 2, (dispH - frameH) / 2),
  };

  function load(file: Blob) {
    const url = URL.createObjectURL(file);
    const img = new Image();
    img.onload = () => {
      setPhoto((prev) => {
        if (prev) URL.revokeObjectURL(prev.url);
        return { img, url };
      });
      setZoom(1);
      setOffset({ x: 0, y: 0 });
    };
    img.src = url;
  }

  function choosePreset(key: string) {
    setPresetKey(key);
    setZoom(1);
    setOffset({ x: 0, y: 0 });
  }

  // Re-render the output whenever the crop or target changes.
  useEffect(() => {
    if (!photo) return;
    let cancelled = false;
    const timer = setTimeout(async () => {
      const canvas = document.createElement("canvas");
      canvas.width = size.w;
      canvas.height = size.h;
      const ctx = canvas.getContext("2d")!;
      ctx.fillStyle = "#ffffff";
      ctx.fillRect(0, 0, size.w, size.h);
      ctx.imageSmoothingQuality = "high";
      const srcW = frameW / scale;
      const srcH = frameH / scale;
      const cx = nw / 2 - pos.x / scale;
      const cy = nh / 2 - pos.y / scale;
      ctx.drawImage(photo.img, cx - srcW / 2, cy - srcH / 2, srcW, srcH, 0, 0, size.w, size.h);

      const { blob, quality } = await compressToLimit(canvas, size.kb);
      if (cancelled) return;
      setResult((prev) => {
        if (prev) URL.revokeObjectURL(prev.url);
        return { url: URL.createObjectURL(blob), bytes: blob.size, quality, fits: size.kb === null || blob.size <= size.kb * 1024 };
      });
    }, 150);
    return () => {
      cancelled = true;
      clearTimeout(timer);
    };
  }, [photo, size.w, size.h, size.kb, frameW, frameH, scale, nw, nh, pos.x, pos.y]);

  // Wheel zoom needs a non-passive listener so the page doesn't scroll.
  useEffect(() => {
    const el = frameRef.current;
    if (!el) return;
    const onWheel = (e: WheelEvent) => {
      e.preventDefault();
      setZoom((z) => clamp(z * (e.deltaY < 0 ? 1.1 : 1 / 1.1), 1, MAX_ZOOM));
    };
    el.addEventListener("wheel", onWheel, { passive: false });
    return () => el.removeEventListener("wheel", onWheel);
  }, [photo]);

  function onPointerDown(e: PointerEvent<HTMLDivElement>) {
    e.currentTarget.setPointerCapture(e.pointerId);
    drag.current = { px: e.clientX, py: e.clientY, ox: pos.x, oy: pos.y };
  }
  function onPointerMove(e: PointerEvent<HTMLDivElement>) {
    const d = drag.current;
    if (d) setOffset({ x: d.ox + e.clientX - d.px, y: d.oy + e.clientY - d.py });
  }
  function onKeyDown(e: KeyboardEvent) {
    const step = e.shiftKey ? 30 : 8;
    const moves: Record<string, [number, number]> = { ArrowLeft: [step, 0], ArrowRight: [-step, 0], ArrowUp: [0, step], ArrowDown: [0, -step] };
    if (moves[e.key]) setOffset({ x: pos.x + moves[e.key][0], y: pos.y + moves[e.key][1] });
    else if (e.key === "+" || e.key === "=") setZoom((z) => clamp(z * 1.1, 1, MAX_ZOOM));
    else if (e.key === "-") setZoom((z) => clamp(z / 1.1, 1, MAX_ZOOM));
    else return;
    e.preventDefault();
  }

  function onDrop(e: DragEvent) {
    e.preventDefault();
    setDragOver(false);
    const file = e.dataTransfer.files[0];
    if (file?.type.startsWith("image/")) load(file);
  }

  async function loadSample() {
    load(await drawSamplePortrait());
  }

  return (
    <div className={styles.card}>
      <header className={styles.head}>
        <h3 className={styles.title}>Photo resizer for forms</h3>
        <p className={styles.subtitle}>Crop, resize and compress to the exact size a form asks for.</p>
      </header>

      <div className={styles.presets} role="radiogroup" aria-label="Required size">
        {[...PRESETS, null].map((p) => {
          const key = p?.key ?? "custom";
          return (
            <button
              key={key}
              type="button"
              role="radio"
              aria-checked={presetKey === key}
              className={styles.preset}
              onClick={() => choosePreset(key)}
            >
              <span className={styles.presetName}>{p ? p.label : "Custom"}</span>
              <span className={styles.presetDetail}>
                {p ? `${p.w}×${p.h}${p.kb ? ` · ≤${p.kb} KB` : ""}` : "Your size"}
              </span>
            </button>
          );
        })}
      </div>

      {!preset && (
        <div className={styles.custom}>
          {(["w", "h", "kb"] as const).map((k) => (
            <label key={k} className={styles.customField}>
              <span>{k === "w" ? "Width (px)" : k === "h" ? "Height (px)" : "Max KB"}</span>
              <input
                inputMode="numeric"
                value={custom[k]}
                placeholder={k === "kb" ? "No limit" : ""}
                onChange={(e) => /^\d*$/.test(e.target.value) && setCustom((c) => ({ ...c, [k]: e.target.value }))}
              />
            </label>
          ))}
        </div>
      )}
      <p className={styles.disclaimer}>Common sizes. Always check your form&apos;s own instructions.</p>

      {!photo ? (
        <label
          className={styles.dropzone}
          data-over={dragOver}
          onDragOver={(e) => {
            e.preventDefault();
            setDragOver(true);
          }}
          onDragLeave={() => setDragOver(false)}
          onDrop={onDrop}
        >
          <input
            type="file"
            accept="image/*"
            className={styles.fileInput}
            onChange={(e) => e.target.files?.[0] && load(e.target.files[0])}
          />
          <svg viewBox="0 0 24 24" width="28" height="28" aria-hidden="true" className={styles.dropIcon}>
            <path d="M12 16V4m0 0-4 4m4-4 4 4M4 16v2a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-2" />
          </svg>
          <span className={styles.dropTitle}>Drop a photo here, or click to choose</span>
          <span className={styles.dropNote}>JPG or PNG. It never leaves this device.</span>
          <button
            type="button"
            className={styles.sampleLink}
            onClick={(e) => {
              e.preventDefault();
              loadSample();
            }}
          >
            Try a sample photo
          </button>
        </label>
      ) : (
        <div className={styles.body}>
          <div className={styles.editor}>
            <div
              ref={frameRef}
              className={styles.frame}
              style={{ width: frameW, height: frameH }}
              tabIndex={0}
              role="application"
              aria-label="Crop area. Drag or use arrow keys to move, plus and minus to zoom."
              onPointerDown={onPointerDown}
              onPointerMove={onPointerMove}
              onPointerUp={() => (drag.current = null)}
              onPointerCancel={() => (drag.current = null)}
              onKeyDown={onKeyDown}
            >
              {/* eslint-disable-next-line @next/next/no-img-element */}
              <img
                src={photo.url}
                alt=""
                draggable={false}
                className={styles.photo}
                style={{ width: dispW, height: dispH, transform: `translate(-50%, -50%) translate(${pos.x}px, ${pos.y}px)` }}
              />
              <div className={styles.thirds} aria-hidden="true" />
              {size.guide && <div className={styles.faceGuide} aria-hidden="true" />}
            </div>
            <label className={styles.zoom}>
              <span>Zoom</span>
              <input
                type="range"
                min={1}
                max={MAX_ZOOM}
                step={0.01}
                value={zoom}
                onChange={(e) => setZoom(Number(e.target.value))}
              />
            </label>
            <p className={styles.hint}>Drag to move · scroll to zoom</p>
          </div>

          <div className={styles.output}>
            <span className={styles.outputLabel}>Result</span>
            <div className={styles.preview} style={{ aspectRatio: `${size.w} / ${size.h}` }}>
              {result && (
                // eslint-disable-next-line @next/next/no-img-element
                <img src={result.url} alt={`Resized photo, ${size.w} by ${size.h} pixels`} />
              )}
            </div>
            <dl className={styles.facts}>
              <div>
                <dt>Size</dt>
                <dd>
                  {size.w} × {size.h} px
                </dd>
              </div>
              <div>
                <dt>File</dt>
                <dd>
                  {result ? kb(result.bytes) : "…"}
                  {size.kb && <span className={styles.limit}> of {size.kb} KB max</span>}
                </dd>
              </div>
              <div>
                <dt>Quality</dt>
                <dd>{result ? `${Math.round(result.quality * 100)}%` : "…"}</dd>
              </div>
            </dl>
            {result && (
              <p className={styles.status} data-ok={result.fits}>
                <span aria-hidden="true">{result.fits ? "✓" : "!"}</span>
                {result.fits ? "Ready for upload" : `Still over ${size.kb} KB. Try a smaller size or a plainer background.`}
              </p>
            )}
            <a
              className={styles.download}
              href={result?.url}
              download={`photo-${size.w}x${size.h}.jpg`}
              aria-disabled={!result}
            >
              Download JPG
            </a>
            <button
              type="button"
              className={styles.replace}
              onClick={() => {
                setPhoto(null);
                setResult(null);
              }}
            >
              Use a different photo
            </button>
          </div>
        </div>
      )}
    </div>
  );
}

function toJpeg(canvas: HTMLCanvasElement, quality: number) {
  return new Promise<Blob>((resolve, reject) =>
    canvas.toBlob((blob) => (blob ? resolve(blob) : reject(new Error("Could not encode image"))), "image/jpeg", quality),
  );
}

/** Highest JPEG quality that fits under `maxKB` (binary search), or 0.92 when there is no limit. */
export async function compressToLimit(canvas: HTMLCanvasElement, maxKB: number | null) {
  const best = await toJpeg(canvas, 0.92);
  if (maxKB === null || best.size <= maxKB * 1024) return { blob: best, quality: 0.92 };

  let lo = 0.05;
  let hi = 0.92;
  let found: { blob: Blob; quality: number } | null = null;
  for (let i = 0; i < 7; i++) {
    const quality = (lo + hi) / 2;
    const blob = await toJpeg(canvas, quality);
    if (blob.size <= maxKB * 1024) {
      found = { blob, quality };
      lo = quality;
    } else {
      hi = quality;
    }
  }
  return found ?? { blob: await toJpeg(canvas, 0.05), quality: 0.05 };
}

/** A simple illustrated portrait so the demo works without uploading anything. */
export function drawSamplePortrait() {
  const canvas = document.createElement("canvas");
  canvas.width = 900;
  canvas.height = 1100;
  const ctx = canvas.getContext("2d")!;

  const bg = ctx.createLinearGradient(0, 0, 900, 1100);
  bg.addColorStop(0, "#9ec5f4");
  bg.addColorStop(1, "#cde2fb");
  ctx.fillStyle = bg;
  ctx.fillRect(0, 0, 900, 1100);

  // Shoulders and collar
  ctx.fillStyle = "#1c3557";
  ctx.beginPath();
  ctx.ellipse(450, 1100, 380, 300, 0, Math.PI, 0);
  ctx.fill();
  ctx.fillStyle = "#ffffff";
  ctx.beginPath();
  ctx.moveTo(380, 820);
  ctx.lineTo(450, 930);
  ctx.lineTo(520, 820);
  ctx.closePath();
  ctx.fill();

  // Neck and face
  ctx.fillStyle = "#c98d63";
  ctx.fillRect(400, 640, 100, 200);
  ctx.fillStyle = "#d9a07a";
  ctx.beginPath();
  ctx.ellipse(450, 520, 170, 210, 0, 0, Math.PI * 2);
  ctx.fill();

  // Hair
  ctx.fillStyle = "#231a14";
  ctx.beginPath();
  ctx.ellipse(450, 400, 185, 130, 0, Math.PI, 0);
  ctx.fill();

  // Eyes and smile
  ctx.fillStyle = "#231a14";
  for (const x of [385, 515]) {
    ctx.beginPath();
    ctx.ellipse(x, 520, 14, 18, 0, 0, Math.PI * 2);
    ctx.fill();
  }
  ctx.strokeStyle = "#8a4b33";
  ctx.lineWidth = 10;
  ctx.lineCap = "round";
  ctx.beginPath();
  ctx.arc(450, 600, 60, 0.2 * Math.PI, 0.8 * Math.PI);
  ctx.stroke();

  return new Promise<Blob>((resolve) => canvas.toBlob((b) => resolve(b!), "image/jpeg", 0.95));
}