"use client";

// 종목 페이지의 사이드 메모 패널.
// Toss "투자 메모" 패턴 — 진입 이유, 관전 포인트를 짧게 적는 자리.
// localStorage 만 사용, 서버 전송 없음.

import { useEffect, useMemo, useState } from "react";
import { NOTE_MAX_LEN, readNote, writeNote, type Note } from "../lib/notes";

type Props = {
  code: string;
};

// '방금 전', '5분 전', '오늘 14:30', 'YYYY-MM-DD' 단계로 압축.
function fmtUpdatedAt(iso: string): string {
  const t = Date.parse(iso);
  if (!Number.isFinite(t)) return "";
  const now = Date.now();
  const diffSec = Math.max(0, Math.floor((now - t) / 1000));
  if (diffSec < 60) return "방금 전";
  const diffMin = Math.floor(diffSec / 60);
  if (diffMin < 60) return `${diffMin}분 전`;
  const d = new Date(t);
  const pad = (n: number) => String(n).padStart(2, "0");
  const ymd = `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
  const hm = `${pad(d.getHours())}:${pad(d.getMinutes())}`;
  // 같은 날짜면 '오늘 HH:MM', 아니면 'YYYY-MM-DD'
  const today = new Date();
  if (
    today.getFullYear() === d.getFullYear() &&
    today.getMonth() === d.getMonth() &&
    today.getDate() === d.getDate()
  ) {
    return `오늘 ${hm}`;
  }
  return ymd;
}

export function InvestmentNote({ code }: Props) {
  const [text, setText] = useState("");
  const [saved, setSaved] = useState<Note | null>(null);
  const [feedback, setFeedback] = useState<string | null>(null);

  useEffect(() => {
    const n = readNote(code);
    setSaved(n);
    setText(n?.text ?? "");
    setFeedback(null);
  }, [code]);

  const dirty = (saved?.text ?? "") !== text;

  // 저장 직후 잠깐 띄우는 toast 같은 안내. dirty 또는 종목 전환 시 자동 해제.
  useEffect(() => {
    if (!feedback) return;
    const h = window.setTimeout(() => setFeedback(null), 2500);
    return () => window.clearTimeout(h);
  }, [feedback]);

  const remaining = useMemo(() => NOTE_MAX_LEN - text.length, [text]);

  const save = () => {
    const next = writeNote(code, text);
    setSaved(next);
    setText(next?.text ?? "");
    setFeedback(next ? "저장됨" : "저장 안됨");
  };

  return (
    <div className="rounded-lg border border-zinc-800 bg-zinc-900/40 p-3">
      <div className="mb-2 flex items-baseline justify-between">
        <h3 className="text-xs font-semibold text-zinc-300">투자 메모</h3>
        <span className="text-[10px] text-zinc-500">
          {saved ? fmtUpdatedAt(saved.updatedAt) : "비공개 · 브라우저 저장"}
        </span>
      </div>
      <textarea
        value={text}
        onChange={(e) => setText(e.target.value.slice(0, NOTE_MAX_LEN))}
        placeholder="이 종목에 대한 관전 포인트, 진입/청산 근거 등을 적어두세요."
        rows={4}
        className="w-full resize-y rounded border border-zinc-800 bg-zinc-950/50 px-2 py-1.5 text-[12px] leading-relaxed text-zinc-100 outline-none focus:border-zinc-600"
        spellCheck={false}
      />
      <div className="mt-2 flex items-center justify-between">
        <span className="text-[10px] tabular-nums text-zinc-500">
          {remaining.toLocaleString()}자 남음
        </span>
        <div className="flex items-center gap-2">
          {feedback && (
            <span className="text-[10px] text-zinc-400" aria-live="polite">
              {feedback}
            </span>
          )}
          <button
            type="button"
            onClick={save}
            disabled={!dirty}
            className="rounded-md border border-zinc-700 bg-zinc-800/80 px-2 py-1 text-[11px] text-zinc-100 transition hover:border-zinc-500 disabled:cursor-not-allowed disabled:opacity-40"
          >
            저장
          </button>
        </div>
      </div>
    </div>
  );
}