"use client";

import { useEffect, useRef, useState } from "react";
import { motion, useInView, useReducedMotion } from "motion/react";

type ReceiptItem = { label: string; price: string };

type ReceiptToastProps = {
  /** Shop or event name, printed first. */
  title?: string;
  /** Small line under the title. */
  meta?: string;
  /** The lines of the receipt. */
  items?: ReceiptItem[];
  /** The total, in your own format. */
  total?: string;
  /** Last line, above the barcode. */
  footer?: string;
  /** Tears the paper off by itself this many ms after printing. 0 keeps it. */
  duration?: number;
  /** Called when the paper is torn off. */
  onTear?: () => void;
  /** Set the width here. Everything scales with it. */
  className?: string;
};

type Row = { kind: "title" | "meta" | "rule" | "item" | "total" | "footer" | "code"; left?: string; right?: string; h: number };

const ITEMS: ReceiptItem[] = [
  { label: "Monthly plan", price: "₹499" },
  { label: "Extra seat x 2", price: "₹198" },
  { label: "Discount", price: "-₹50" },
];

const LINE = 6.3; // one printed line, in cqw
const PAD = 2;
const TEETH = 22;
const BAR_WIDTHS = [1, 3, 1, 2, 1, 1, 3, 2, 1, 2, 3, 1, 1, 2, 1, 3, 2, 1, 1, 3, 1, 2, 2, 1, 3, 1, 1, 2, 3, 1];

// Both ends of the paper are torn: a saw edge at top and bottom.
const EDGE = (() => {
  const top: string[] = [];
  const bottom: string[] = [];
  for (let i = 0; i <= TEETH * 2; i++) {
    const x = (i / (TEETH * 2)) * 100;
    top.push(`${x}% ${i % 2 ? "1.1cqw" : "0"}`);
    bottom.unshift(`${x}% calc(100% - ${i % 2 ? "1.1cqw" : "0px"})`);
  }
  return `polygon(${[...top, ...bottom].join(",")})`;
})();

/* ReceiptToast: the toast is a slip from a thermal printer. Paper feeds up out of the slot in small jerks, one line at a time, and you drag it up or press Tear to rip it off against the saw bar. */
export function ReceiptToast({ title = "Payment received", meta = "Order 20418 · Paid by UPI", items = ITEMS, total = "₹647", footer = "Thank you. Come again.", duration = 0, onTear, className = "w-full max-w-sm" }: ReceiptToastProps) {
  const reduce = useReducedMotion();
  const box = useRef<HTMLDivElement>(null);
  const seen = useInView(box, { once: true, amount: 0.2 });

  const rows: Row[] = [
    { kind: "title", left: title, h: 1.5 },
    { kind: "meta", left: meta, h: 1 },
    { kind: "rule", h: 0.7 },
    ...items.map((it): Row => ({ kind: "item", left: it.label, right: it.price, h: 1 })),
    { kind: "rule", h: 0.7 },
    { kind: "total", left: "Total", right: total, h: 1.4 },
    { kind: "footer", left: footer, h: 1.1 },
    { kind: "code", h: 2 },
  ];
  const height = rows.reduce((sum, r) => sum + r.h * LINE, PAD * 2);

  const [run, setRun] = useState(0); // goes up by one for each slip
  const [printed, setPrinted] = useState(0);
  const [torn, setTorn] = useState(false);
  const started = seen && run % 2 === 0;
  const done = printed >= rows.length;
  const printing = started && !done && !torn;

  useEffect(() => {
    if (!printing) return;
    const id = setTimeout(() => setPrinted(reduce ? rows.length : (p) => p + 1), reduce ? 0 : 150);
    return () => clearTimeout(id);
  }, [printing, printed, reduce, rows.length]);

  const tear = () => {
    if (done && !torn) setTorn(true);
  };

  useEffect(() => {
    if (!done || torn || !duration) return;
    const id = setTimeout(() => setTorn(true), duration);
    return () => clearTimeout(id);
  }, [done, torn, duration]);

  const out = rows.slice(0, printed).reduce((sum, r) => sum + r.h * LINE, printed ? PAD : 0);
  const empty = run % 2 === 1;

  return (
    <div ref={box} className={`@container ${className}`}>
      <div className="relative select-none" style={{ paddingTop: `${height}cqw` }}>
        {/* Below the slot nothing shows; above it the paper is free to fly. */}
        <div className="absolute inset-x-[9cqw] top-[-40cqw]" style={{ height: `${height + 41}cqw`, clipPath: "inset(0 -30cqw 0 -30cqw)" }} aria-hidden>
          <motion.div
            key={run}
            className="absolute inset-x-0 bottom-0 cursor-grab touch-none active:cursor-grabbing"
            drag={done && !torn ? "y" : false}
            dragConstraints={{ top: -70, bottom: 0 }}
            dragElastic={0.25}
            dragSnapToOrigin
            onDragEnd={(_, info) => {
              if (info.offset.y < -34) tear();
            }}
            animate={torn ? { y: "-130%", x: "6%", rotate: -7, opacity: 0 } : { y: 0, x: 0, rotate: 0, opacity: 1 }}
            transition={torn ? { duration: reduce ? 0 : 0.6, ease: [0.3, 0, 0.7, 1] } : { duration: 0 }}
            onAnimationComplete={() => {
              if (!torn) return;
              setTorn(false);
              setPrinted(0);
              setRun((r) => r + 1);
              onTear?.();
            }}
          >
            <div
              style={{
                height: `${height}cqw`,
                transform: `translateY(${height - out}cqw)`,
                transition: reduce ? undefined : "transform 130ms steps(3)",
                clipPath: EDGE,
                padding: `${PAD}cqw 6cqw`,
                background: "linear-gradient(90deg, #dcd7c8, #f6f3ea 8%, #fbf9f2 50%, #f3f0e6 92%, #d8d3c3)",
                color: "#3f3c58",
                fontFamily: "ui-monospace, 'Cascadia Mono', Consolas, monospace",
                fontSize: "3.9cqw",
                lineHeight: 1,
              }}
            >
              {rows.map((r, i) => (
                <div key={i} className="flex items-center justify-between gap-[2cqw] whitespace-nowrap" style={{ height: `${r.h * LINE}cqw` }}>
                  {r.kind === "rule" && <div className="w-full border-t border-dashed" style={{ borderColor: "#3f3c5899" }} />}
                  {r.kind === "code" && (
                    <div className="flex h-[8.4cqw] w-full justify-center">
                      {BAR_WIDTHS.map((w, b) => (
                        <span key={b} style={{ width: `${w * 0.62}cqw`, marginRight: `${(b % 3) * 0.3 + 0.28}cqw`, background: "#3f3c58" }} />
                      ))}
                    </div>
                  )}
                  {r.kind === "title" && <span className="w-full text-center font-bold" style={{ fontSize: "5cqw" }}>{r.left}</span>}
                  {(r.kind === "meta" || r.kind === "footer") && <span className="w-full truncate text-center" style={{ fontSize: "3.1cqw", opacity: 0.78 }}>{r.left}</span>}
                  {(r.kind === "item" || r.kind === "total") && (
                    <>
                      <span className={`truncate ${r.kind === "total" ? "font-bold" : ""}`}>{r.left}</span>
                      <span className={r.kind === "total" ? "font-bold" : ""} style={r.kind === "total" ? { fontSize: "4.8cqw" } : undefined}>{r.right}</span>
                    </>
                  )}
                </div>
              ))}
            </div>
          </motion.div>
          {/* Shadow where the paper leaves the slot. */}
          <div className="pointer-events-none absolute inset-x-0 bottom-0 h-[5cqw]" style={{ background: "linear-gradient(0deg, #0006, transparent)", opacity: printed ? 1 : 0 }} />
        </div>

        {/* The printer. */}
        <motion.div
          className="relative rounded-[3cqw]"
          animate={printing && !reduce ? { y: [0, 0.5, 0] } : { y: 0 }}
          transition={printing ? { duration: 0.15, repeat: Infinity } : { duration: 0.1 }}
          style={{ padding: "1.4cqw 3cqw 3cqw", background: "linear-gradient(180deg, #3a3c41, #26272b 45%, #1c1d20)", boxShadow: "0 1.6cqw 3.4cqw #0008, inset 0 0.3cqw 0 #ffffff24" }}
        >
          {/* Saw bar with the slot under it. */}
          <div className="h-[1.5cqw]" style={{ background: "repeating-linear-gradient(90deg, #cfd2d6 0 1.1cqw, #6f7378 1.1cqw 2.2cqw)", clipPath: "polygon(0 0, 100% 0, 100% 45%, 0 100%)" }} aria-hidden />
          <div className="mx-[4cqw] h-[1.2cqw] rounded-b-[1cqw] bg-black" aria-hidden />
          <div className="mt-[1.8cqw] flex items-center justify-between gap-[2cqw]">
            <div className="flex items-center gap-[1.6cqw]" aria-hidden>
              <motion.span
                className="block size-[2.2cqw] rounded-full"
                animate={printing && !reduce ? { opacity: [1, 0.3, 1] } : { opacity: 1 }}
                transition={printing ? { duration: 0.4, repeat: Infinity } : { duration: 0.1 }}
                style={{ background: printing ? "#6fe08a" : done ? "#f5b64a" : "#55585e", boxShadow: printing ? "0 0 2cqw #6fe08a" : done ? "0 0 1.6cqw #f5b64a" : "none" }}
              />
              <span className="font-mono text-[2.7cqw] tracking-[0.14em]" style={{ color: "#9ea1a8" }}>{printing ? "PRINTING" : done ? "READY" : "IDLE"}</span>
            </div>
            <button
              type="button"
              disabled={printing || torn || !seen}
              onClick={() => (done ? tear() : setRun((r) => r + 1))}
              className="cursor-pointer rounded-[1.4cqw] px-[3.4cqw] py-[1.5cqw] font-mono text-[3.1cqw] font-semibold disabled:cursor-default disabled:opacity-40"
              style={{ color: "#17181a", background: "linear-gradient(180deg, #e6e7ea, #b7b9be)", boxShadow: "0 0.5cqw 0 #6c6e73" }}
            >
              {empty || !done ? "Print" : "Tear"}
            </button>
          </div>
        </motion.div>
      </div>
      <span role="status" className="sr-only">
        {done ? `${title}. ${meta}. ${items.map((i) => `${i.label} ${i.price}`).join(", ")}. Total ${total}. ${footer}` : ""}
      </span>
    </div>
  );
}