"use client";

import { useId, useRef, useState, type FocusEvent, type KeyboardEvent, type PointerEvent } from "react";
import { motion, useReducedMotion } from "motion/react";

export type ContactSheetFrame = {
  src: string;
  alt: string;
  /** Crop inside the frame, as CSS object-position. Two crops of one picture read as a burst. */
  position?: string;
};

type ContactSheetProps = {
  frames: ContactSheetFrame[];
  /** Frames on each film strip. */
  perRow?: number;
  /** Frames circled at the start, by index. */
  picked?: number[];
  /** How many times the loupe enlarges. */
  zoom?: number;
  /** Printed on the film edge. */
  edge?: string;
  /** Written on the paper margin. */
  title?: string;
  /** Called with the picked indexes after each press. */
  onPick?: (picked: number[]) => void;
  className?: string;
};

type Lens = { i: number; w: number; h: number; x: number; y: number; fx: number; fy: number };

const HOLES = `url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='14'%3E%3Crect x='6' y='2' width='12' height='10' rx='2.6' fill='%23ece7da'/%3E%3C/svg%3E")`;
const LOOP = "M13 44C6 20 34 6 58 7c26 1 39 17 34 37-4 16-34 23-58 19C16 60 6 48 15 29";
const HAND = { fontFamily: '"Segoe Print", "Bradley Hand", "Comic Sans MS", cursive' };

function Holes() {
  return <span aria-hidden className="block h-[0.9em]" style={{ backgroundImage: HOLES, backgroundSize: "1.2em 100%" }} />;
}

/* ContactSheet: a darkroom print of a whole roll. Hover a frame for a loupe, press it to circle it in red grease pencil. */
export function ContactSheet({ frames, perRow = 4, picked = [], zoom = 2.6, edge = "SAFETY FILM 400", title = "Roll 12", onPick, className = "" }: ContactSheetProps) {
  const reduce = useReducedMotion();
  const id = useId();
  const root = useRef<HTMLDivElement>(null);
  const [marks, setMarks] = useState(picked);
  const [cursor, setCursor] = useState(0);
  const [lens, setLens] = useState<Lens | null>(null);
  const [lensOn, setLensOn] = useState(false);

  const rows = Array.from({ length: Math.ceil(frames.length / perRow) }, (_, r) => r * perRow);

  function aim(i: number, el: HTMLElement, cx: number, cy: number) {
    const box = root.current!.getBoundingClientRect();
    const f = el.getBoundingClientRect();
    const edge = box.width * 0.18; // Half the loupe, so all of it stays on the sheet.
    const x = Math.min(box.width - edge, Math.max(edge, cx - box.left));
    const y = Math.min(box.height - edge, Math.max(edge, cy - box.top));
    setLens({ i, w: f.width, h: f.height, x, y, fx: (cx - f.left) / f.width, fy: (cy - f.top) / f.height });
    setLensOn(true);
  }

  function hover(i: number, e: PointerEvent<HTMLButtonElement>) {
    if (e.pointerType === "mouse") aim(i, e.currentTarget, e.clientX, e.clientY);
  }

  function focused(i: number, e: FocusEvent<HTMLButtonElement>) {
    setCursor(i);
    if (!e.currentTarget.matches(":focus-visible")) return;
    const f = e.currentTarget.getBoundingClientRect();
    aim(i, e.currentTarget, f.left + f.width / 2, f.top + f.height / 2);
  }

  function toggle(i: number) {
    const next = marks.includes(i) ? marks.filter((m) => m !== i) : [...marks, i];
    setMarks(next);
    onPick?.(next);
  }

  function arrows(i: number, e: KeyboardEvent<HTMLButtonElement>) {
    const step = { ArrowRight: 1, ArrowLeft: -1, ArrowDown: perRow, ArrowUp: -perRow }[e.key];
    if (!step) return;
    e.preventDefault();
    const to = i + step;
    if (to < 0 || to >= frames.length) return;
    root.current!.querySelectorAll<HTMLButtonElement>("[data-frame]")[to]?.focus();
  }

  return (
    <div className={`@container w-[32rem] ${className}`}>
      <div ref={root} role="group" aria-label={title} onPointerLeave={() => setLensOn(false)} className="relative overflow-hidden bg-[#ece7da] p-[1em] text-[2.4cqw] leading-none shadow-[0_1em_2em_-0.8em_rgba(0,0,0,0.7)]">
        <svg aria-hidden className="absolute size-0">
          <filter id={id}>
            <feTurbulence type="fractalNoise" baseFrequency="0.09" numOctaves="2" seed="4" />
            <feDisplacementMap in="SourceGraphic" scale="3" />
          </filter>
        </svg>

        <div className="flex flex-col gap-[0.5em]">
          {rows.map((start, r) => (
            <div key={start} className="bg-[#100e0c] px-[0.5em]">
              <Holes />
              <div aria-hidden className="grid h-[0.8em] items-center text-[#d99a2b]" style={{ gridTemplateColumns: `repeat(${perRow}, 1fr)` }}>
                {Array.from({ length: perRow }, (_, c) => (
                  <span key={c} className="truncate pl-[0.8em] font-mono text-[0.58em]">{start + c + 1}{r % 2 ? "A" : ""}</span>
                ))}
              </div>
              <div className="grid gap-[0.34em]" style={{ gridTemplateColumns: `repeat(${perRow}, 1fr)` }}>
                {Array.from({ length: perRow }, (_, c) => {
                  const i = start + c;
                  const frame = frames[i];
                  if (!frame) return <span key={c} aria-hidden className="block aspect-[3/2] bg-[#060505]" />;
                  const on = marks.includes(i);
                  return (
                    <button
                      key={c}
                      type="button"
                      data-frame
                      tabIndex={i === cursor ? 0 : -1}
                      aria-pressed={on}
                      aria-label={`Frame ${i + 1}: ${frame.alt}`}
                      onPointerEnter={(e) => hover(i, e)}
                      onPointerMove={(e) => hover(i, e)}
                      onFocus={(e) => focused(i, e)}
                      onBlur={() => setLensOn(false)}
                      onKeyDown={(e) => arrows(i, e)}
                      onClick={() => toggle(i)}
                      className={`relative block aspect-[3/2] cursor-zoom-in outline-none focus-visible:ring-[0.14em] focus-visible:ring-[#ffcb6b] ${on ? "z-10" : ""}`}
                    >
                      <span className="absolute inset-0 overflow-hidden">
                        <img src={frame.src} alt="" draggable={false} className="size-full object-cover contrast-[1.08]" style={{ objectPosition: frame.position }} />
                      </span>
                      {on && (
                        <svg aria-hidden viewBox="0 0 100 70" preserveAspectRatio="none" className="pointer-events-none absolute -inset-[7%] size-[114%] overflow-visible" style={{ transform: `rotate(${(i % 3) * 3 - 3}deg) scaleX(${i % 2 ? -1 : 1})` }}>
                          <motion.path
                            d={LOOP}
                            fill="none"
                            stroke="#e0241b"
                            strokeWidth="3.4"
                            strokeLinecap="round"
                            filter={`url(#${id})`}
                            initial={{ pathLength: reduce ? 1 : 0 }}
                            animate={{ pathLength: 1 }}
                            transition={{ duration: 0.42, ease: "easeInOut" }}
                          />
                        </svg>
                      )}
                    </button>
                  );
                })}
              </div>
              <div aria-hidden className="flex h-[0.8em] items-center justify-between overflow-hidden whitespace-nowrap font-mono text-[#d99a2b]">
                <span className="pl-[0.8em] text-[0.5em] tracking-[0.2em]">{edge}</span>
                <span className="pr-[0.8em] text-[0.5em] tracking-[0.2em]">{edge}</span>
              </div>
              <Holes />
            </div>
          ))}
        </div>

        <div className="mt-[0.7em] flex items-baseline justify-between text-[1.35em] text-[#2b2723]" style={HAND}>
          <span>{title}</span>
          <span aria-live="polite" className="text-[#d3261d]">{marks.length} picked</span>
        </div>

        {lens && (
          <div
            aria-hidden
            className={`pointer-events-none absolute z-20 size-[14em] -translate-x-1/2 -translate-y-1/2 overflow-hidden rounded-full bg-[#0a0908] shadow-[0_0_0_0.32em_#23211e,0_0_0_0.42em_#77726a,0_0.9em_1.6em_rgba(0,0,0,0.65)] transition-[opacity,scale] duration-150 ${lensOn ? "scale-100 opacity-100" : "scale-75 opacity-0"}`}
            style={{ left: lens.x, top: lens.y }}
          >
            <img
              src={frames[lens.i].src}
              alt=""
              className="absolute top-1/2 left-1/2 max-w-none object-cover contrast-[1.08]"
              style={{ width: lens.w * zoom, height: lens.h * zoom, objectPosition: frames[lens.i].position, transform: `translate(${-lens.fx * lens.w * zoom}px, ${-lens.fy * lens.h * zoom}px)` }}
            />
            <span className="absolute inset-0 rounded-full bg-[radial-gradient(circle_at_34%_28%,rgba(255,255,255,0.3),transparent_34%),radial-gradient(circle,transparent_62%,rgba(0,0,0,0.5))]" />
          </div>
        )}
      </div>
    </div>
  );
}