/* =====================================================================
   ValenceChart — 감정 밸런스 타임라인 (SVG 라인 차트).
   외부 ref의 Emotional Valence Timeline 차용 → Vignette 토큰 리스킨.
   · 내담자 valence = 실선(테라코타 --clay)
   · 상담자 baseline = 점선(세이지 --accent-bright)
   범례·시간축·0선 포함. preserveAspectRatio="none" 로 컨테이너 채움.
   순흑/순백 금지 — stroke 는 토큰 currentColor 계열만.
   ===================================================================== */

import type { ValencePoint } from "./mock";

export interface ValenceChartProps {
  client: ValencePoint[];
  baseline: ValencePoint[];
  /** 시간축 라벨 (좌→우) */
  xLabels: string[];
}

/** valence(-1~1) → SVG y(0~100, 위가 +1). */
function toY(v: number): number {
  const clamped = Math.max(-1, Math.min(1, v));
  return 50 - clamped * 45; // +1 → 5, 0 → 50, -1 → 95 (상하 5% 여백)
}

/** 점 배열 → 부드러운 Catmull-Rom→베지어 path d. (단조 곡선, 과한 출렁임 없게) */
function smoothPath(points: ValencePoint[]): string {
  if (points.length === 0) return "";
  const pts = points.map((p) => ({ x: p.t * 100, y: toY(p.v) }));
  if (pts.length === 1) return `M${pts[0].x},${pts[0].y}`;

  let d = `M${pts[0].x.toFixed(2)},${pts[0].y.toFixed(2)}`;
  for (let i = 0; i < pts.length - 1; i++) {
    const p0 = pts[i - 1] ?? pts[i];
    const p1 = pts[i];
    const p2 = pts[i + 1];
    const p3 = pts[i + 2] ?? p2;
    // Catmull-Rom → 베지어 (tension 1/6)
    const c1x = p1.x + (p2.x - p0.x) / 6;
    const c1y = p1.y + (p2.y - p0.y) / 6;
    const c2x = p2.x - (p3.x - p1.x) / 6;
    const c2y = p2.y - (p3.y - p1.y) / 6;
    d += ` C${c1x.toFixed(2)},${c1y.toFixed(2)} ${c2x.toFixed(2)},${c2y.toFixed(2)} ${p2.x.toFixed(2)},${p2.y.toFixed(2)}`;
  }
  return d;
}

export function ValenceChart({ client, baseline, xLabels }: ValenceChartProps) {
  const clientPath = smoothPath(client);
  const baselinePath = smoothPath(baseline);

  return (
    <div className="sr-chart">
      <div className="sr-chart__legend">
        <span className="sr-legend-item">
          <span className="sr-legend-line sr-legend-line--client" />
          내담자 정서가
        </span>
        <span className="sr-legend-item">
          <span className="sr-legend-line sr-legend-line--baseline" />
          상담자 기준선
        </span>
      </div>

      <div className="sr-chart__plot">
        <div className="sr-chart__yaxis" aria-hidden="true">
          <span>+1.0</span>
          <span>0.0</span>
          <span>-1.0</span>
        </div>

        <div className="sr-chart__canvas">
          <svg
            className="sr-chart__svg"
            viewBox="0 0 100 100"
            preserveAspectRatio="none"
            role="img"
            aria-label="회기 동안 내담자 정서가와 상담자 기준선의 변화 추이"
          >
            {/* 0선 (중립) */}
            <line
              x1="0"
              y1="50"
              x2="100"
              y2="50"
              stroke="var(--hair)"
              strokeWidth="1"
              vectorEffect="non-scaling-stroke"
            />
            {/* 상담자 baseline (점선, 세이지) */}
            <path
              d={baselinePath}
              fill="none"
              stroke="var(--accent-bright)"
              strokeWidth="2"
              strokeDasharray="4 4"
              strokeLinecap="round"
              strokeLinejoin="round"
              vectorEffect="non-scaling-stroke"
              opacity="0.7"
            />
            {/* 내담자 valence (실선, 테라코타) */}
            <path
              d={clientPath}
              fill="none"
              stroke="var(--clay)"
              strokeWidth="2"
              strokeLinecap="round"
              strokeLinejoin="round"
              vectorEffect="non-scaling-stroke"
            />
          </svg>
        </div>

        <div className="sr-chart__xaxis" aria-hidden="true">
          {xLabels.map((label, i) => (
            <span key={i}>{label}</span>
          ))}
        </div>
      </div>
    </div>
  );
}