// FaceScanner.jsx — MediaPipe FaceMesh + gradient mesh overlay + liveness challenges
// Real client-side liveness: blink (EAR), head yaw/pitch, mouth open (MAR), smile
// Draws animated gradient tessellation like immigration kiosk.
import React, { useEffect, useRef, useState, useCallback } from "react";
import { FaceMesh, FACEMESH_TESSELATION, FACEMESH_RIGHT_EYE, FACEMESH_LEFT_EYE, FACEMESH_LIPS, FACEMESH_FACE_OVAL } from "@mediapipe/face_mesh";
import { motion, AnimatePresence } from "framer-motion";
import { Eye, ArrowLeft, ArrowRight, ArrowDown, Smile, Loader2, ShieldCheck, ShieldAlert, RotateCcw } from "lucide-react";

// MediaPipe landmark indexes
const RIGHT_EYE = [33, 160, 158, 133, 153, 144];
const LEFT_EYE = [362, 385, 387, 263, 373, 380];
const UPPER_LIP_CENTER = 13;
const LOWER_LIP_CENTER = 14;
const MOUTH_LEFT = 61;
const MOUTH_RIGHT = 291;
const NOSE_TIP = 1;
const LEFT_CHEEK = 234;
const RIGHT_CHEEK = 454;
const FOREHEAD = 10;
const CHIN = 152;

const CHALLENGE_META = {
  blink: { label: "Silakan Berkedip", subtitle: "Kedipkan mata Anda perlahan", Icon: Eye },
  turn_left: { label: "Tengok ke Kiri", subtitle: "Putar kepala ke kiri", Icon: ArrowLeft },
  turn_right: { label: "Tengok ke Kanan", subtitle: "Putar kepala ke kanan", Icon: ArrowRight },
  nod: { label: "Anggukkan Kepala", subtitle: "Turunkan dagu ke bawah", Icon: ArrowDown },
  smile: { label: "Silakan Senyum", subtitle: "Buka mulut atau senyum lebar", Icon: Smile },
};

function dist(a, b) {
  const dx = a.x - b.x;
  const dy = a.y - b.y;
  return Math.sqrt(dx * dx + dy * dy);
}

function eyeEAR(lm, idx) {
  const p1 = lm[idx[0]];
  const p2 = lm[idx[1]];
  const p3 = lm[idx[2]];
  const p4 = lm[idx[3]];
  const p5 = lm[idx[4]];
  const p6 = lm[idx[5]];
  return (dist(p2, p6) + dist(p3, p5)) / (2 * dist(p1, p4));
}

function mouthOpenness(lm) {
  const v = dist(lm[UPPER_LIP_CENTER], lm[LOWER_LIP_CENTER]);
  const h = dist(lm[MOUTH_LEFT], lm[MOUTH_RIGHT]);
  return v / Math.max(0.0001, h);
}

function mouthWidthRatio(lm) {
  // measure width vs face width (cheeks) — smiling stretches this
  const mw = dist(lm[MOUTH_LEFT], lm[MOUTH_RIGHT]);
  const fw = dist(lm[LEFT_CHEEK], lm[RIGHT_CHEEK]);
  return mw / Math.max(0.0001, fw);
}

// yaw sign: nose x relative to face midline
function estimateYaw(lm) {
  const nose = lm[NOSE_TIP];
  const leftCheek = lm[LEFT_CHEEK];
  const rightCheek = lm[RIGHT_CHEEK];
  const midX = (leftCheek.x + rightCheek.x) / 2;
  const width = rightCheek.x - leftCheek.x;
  // normalized offset [-1..1]
  return (nose.x - midX) / Math.max(0.0001, width / 2);
}

function estimatePitch(lm) {
  const nose = lm[NOSE_TIP];
  const forehead = lm[FOREHEAD];
  const chin = lm[CHIN];
  const midY = (forehead.y + chin.y) / 2;
  const height = chin.y - forehead.y;
  return (nose.y - midY) / Math.max(0.0001, height / 2);
}

/**
 * Draw a gradient tessellation mesh on canvas using MediaPipe connections.
 * Each frame we shift gradient phase so it feels alive.
 */
function drawGradientMesh(ctx, lm, width, height, phase) {
  const grad = ctx.createLinearGradient(0, 0, width, height);
  const p = (phase % 1);
  // rotate stops for animated color travel
  grad.addColorStop((0 + p) % 1, "#8A2BE2");
  grad.addColorStop((0.33 + p) % 1, "#0057FF");
  grad.addColorStop((0.66 + p) % 1, "#00F0FF");
  grad.addColorStop((1 + p) % 1, "#39FF14");
  ctx.strokeStyle = grad;
  ctx.lineWidth = 0.6;
  ctx.globalAlpha = 0.55;
  ctx.beginPath();
  for (const [i, j] of FACEMESH_TESSELATION) {
    const a = lm[i];
    const b = lm[j];
    if (!a || !b) continue;
    ctx.moveTo(a.x * width, a.y * height);
    ctx.lineTo(b.x * width, b.y * height);
  }
  ctx.stroke();

  // Emphasize eyes / mouth / face oval with brighter accent
  ctx.globalAlpha = 0.95;
  ctx.lineWidth = 1.4;
  const accents = [FACEMESH_LEFT_EYE, FACEMESH_RIGHT_EYE, FACEMESH_LIPS, FACEMESH_FACE_OVAL];
  const strokes = ["#00F0FF", "#00F0FF", "#39FF14", "#8A2BE2"];
  accents.forEach((set, k) => {
    ctx.strokeStyle = strokes[k];
    ctx.beginPath();
    for (const [i, j] of set) {
      const a = lm[i];
      const b = lm[j];
      if (!a || !b) continue;
      ctx.moveTo(a.x * width, a.y * height);
      ctx.lineTo(b.x * width, b.y * height);
    }
    ctx.stroke();
  });

  // Dot on key points
  ctx.globalAlpha = 0.9;
  const pts = [NOSE_TIP, FOREHEAD, CHIN, LEFT_CHEEK, RIGHT_CHEEK];
  ctx.fillStyle = "#00F0FF";
  pts.forEach((idx) => {
    const p = lm[idx];
    if (!p) return;
    ctx.beginPath();
    ctx.arc(p.x * width, p.y * height, 2.4, 0, Math.PI * 2);
    ctx.fill();
  });
  ctx.globalAlpha = 1;
}

export default function FaceScanner({
  challenges,
  onCapture,
  onAllChallengesDone,
  autoCapture = false,
  captureOnDone = false,
  width = 640,
  height = 480,
  showChallenges = true,
}) {
  const videoRef = useRef(null);
  const canvasRef = useRef(null);
  const meshRef = useRef(null);
  const streamRef = useRef(null);
  const rafRef = useRef(null);
  const lastLmRef = useRef(null);
  const phaseRef = useRef(0);

  // challenge state
  const [currentIdx, setCurrentIdx] = useState(0);
  const [passed, setPassed] = useState([]);
  const [faceDetected, setFaceDetected] = useState(false);
  const [statusText, setStatusText] = useState("Menunggu wajah…");
  const [ready, setReady] = useState(false);

  // per-challenge internal states
  const stateRef = useRef({
    blinkEyeClosed: false,
    blinkCount: 0,
    baselineYaw: null,
    baselineMouth: null,
    baselineSmile: null,
    baselinePitch: null,
    lastMoveT: 0,
  });

  const currentChallenge = challenges?.[currentIdx];

  const resetInternal = useCallback(() => {
    stateRef.current = {
      blinkEyeClosed: false,
      blinkCount: 0,
      baselineYaw: null,
      baselineMouth: null,
      baselineSmile: null,
      baselinePitch: null,
      lastMoveT: 0,
    };
  }, []);

  const onResults = useCallback(
    (results) => {
      const canvas = canvasRef.current;
      const video = videoRef.current;
      if (!canvas || !video) return;
      const ctx = canvas.getContext("2d");
      const w = canvas.width;
      const h = canvas.height;
      ctx.clearRect(0, 0, w, h);
      phaseRef.current = (phaseRef.current + 0.008) % 1;

      const lm = results.multiFaceLandmarks?.[0];
      if (!lm) {
        setFaceDetected(false);
        setStatusText("Posisikan wajah di tengah kamera…");
        lastLmRef.current = null;
        return;
      }
      setFaceDetected(true);
      lastLmRef.current = lm;
      // draw mesh
      drawGradientMesh(ctx, lm, w, h, phaseRef.current);

      // process current challenge (only if provided)
      if (!challenges || challenges.length === 0) return;
      const chal = challenges[currentIdx];
      if (!chal) return;
      const s = stateRef.current;

      const earR = eyeEAR(lm, RIGHT_EYE);
      const earL = eyeEAR(lm, LEFT_EYE);
      const ear = (earR + earL) / 2;
      const mopen = mouthOpenness(lm);
      const smileRatio = mouthWidthRatio(lm);
      const yaw = estimateYaw(lm);
      const pitch = estimatePitch(lm);

      let done = false;
      let hint = "";
      if (chal === "blink") {
        // baseline eye open ~0.28, closed ~<0.19
        const CLOSED = 0.19;
        const OPEN = 0.26;
        if (!s.blinkEyeClosed && ear < CLOSED) {
          s.blinkEyeClosed = true;
        } else if (s.blinkEyeClosed && ear > OPEN) {
          s.blinkCount += 1;
          s.blinkEyeClosed = false;
        }
        hint = `Blink terdeteksi: ${s.blinkCount}/1`;
        if (s.blinkCount >= 1) done = true;
      } else if (chal === "turn_left" || chal === "turn_right") {
        if (s.baselineYaw == null) s.baselineYaw = yaw;
        // In mirrored video, "turn_left" from user's POV = camera sees nose move right
        const delta = yaw - s.baselineYaw;
        const THRESH = 0.35;
        if (chal === "turn_left" && delta >= THRESH) done = true;
        if (chal === "turn_right" && delta <= -THRESH) done = true;
        hint = `Yaw: ${delta.toFixed(2)}`;
      } else if (chal === "nod") {
        if (s.baselinePitch == null) s.baselinePitch = pitch;
        const delta = pitch - s.baselinePitch;
        if (delta > 0.3) done = true;
        hint = `Pitch: ${delta.toFixed(2)}`;
      } else if (chal === "smile") {
        if (s.baselineMouth == null) s.baselineMouth = mopen;
        if (s.baselineSmile == null) s.baselineSmile = smileRatio;
        const dOpen = mopen - s.baselineMouth;
        const dSmile = smileRatio - s.baselineSmile;
        if (dOpen > 0.06 || dSmile > 0.05 || mopen > 0.35 || smileRatio > 0.55) done = true;
        hint = `Mulut: ${(mopen).toFixed(2)} lebar: ${smileRatio.toFixed(2)}`;
      }

      setStatusText(hint);

      if (done) {
        const newPassed = [...passed, chal];
        setPassed(newPassed);
        resetInternal();
        const next = currentIdx + 1;
        if (next >= challenges.length) {
          setStatusText("Semua verifikasi terlewati");
          if (onAllChallengesDone) onAllChallengesDone(newPassed);
          if (captureOnDone) {
            // capture immediately from current frame
            setTimeout(() => doCapture(), 250);
          }
        } else {
          setCurrentIdx(next);
        }
      }
    },
    // eslint-disable-next-line react-hooks/exhaustive-deps
    [currentIdx, challenges, passed]
  );

  const doCapture = useCallback(() => {
    const video = videoRef.current;
    if (!video) return null;
    const tmp = document.createElement("canvas");
    tmp.width = video.videoWidth || width;
    tmp.height = video.videoHeight || height;
    const tctx = tmp.getContext("2d");
    // Un-mirror capture (backend expects real orientation)
    tctx.save();
    tctx.scale(-1, 1);
    tctx.drawImage(video, -tmp.width, 0, tmp.width, tmp.height);
    tctx.restore();
    const dataUrl = tmp.toDataURL("image/jpeg", 0.85);
    if (onCapture) onCapture(dataUrl);
    return dataUrl;
  }, [onCapture, width, height]);

  // expose capture via ref-like callback
  useEffect(() => {
    // attach capture handler to window if needed? Actually parent uses onCapture
  }, []);

  // Initialize mediapipe + camera
  useEffect(() => {
    let cancelled = false;
    async function init() {
      const mesh = new FaceMesh({
        locateFile: (file) =>
          `https://cdn.jsdelivr.net/npm/@mediapipe/face_mesh/${file}`,
      });
      mesh.setOptions({
        maxNumFaces: 1,
        refineLandmarks: true,
        minDetectionConfidence: 0.6,
        minTrackingConfidence: 0.6,
      });
      mesh.onResults(onResults);
      meshRef.current = mesh;
      try {
        const stream = await navigator.mediaDevices.getUserMedia({
          video: { width: { ideal: 640 }, height: { ideal: 480 }, facingMode: "user" },
          audio: false,
        });
        if (cancelled) {
          stream.getTracks().forEach((t) => t.stop());
          return;
        }
        streamRef.current = stream;
        const video = videoRef.current;
        video.srcObject = stream;
        await video.play();
        setReady(true);
        const loop = async () => {
          if (cancelled) return;
          if (meshRef.current && video.readyState >= 2) {
            try {
              await meshRef.current.send({ image: video });
            } catch (_) {
              // ignore
            }
          }
          rafRef.current = requestAnimationFrame(loop);
        };
        loop();
      } catch (err) {
        setStatusText("Kamera tidak dapat diakses: " + err.message);
      }
    }
    init();
    return () => {
      cancelled = true;
      if (rafRef.current) cancelAnimationFrame(rafRef.current);
      if (streamRef.current) streamRef.current.getTracks().forEach((t) => t.stop());
      try { meshRef.current?.close?.(); } catch (_) {}
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  // update onResults binding when currentIdx changes (React closure)
  useEffect(() => {
    if (meshRef.current) meshRef.current.onResults(onResults);
  }, [onResults]);

  const progress = challenges?.length ? passed.length / challenges.length : 0;
  const currentMeta = currentChallenge ? CHALLENGE_META[currentChallenge] : null;

  return (
    <div className="relative w-full" data-testid="face-scanner">
      <div
        className="relative mx-auto rounded-2xl overflow-hidden corner-brackets"
        style={{ maxWidth: "760px", aspectRatio: "4/3" }}
      >
        <span className="cb1" />
        <span className="cb2" />
        <video
          ref={videoRef}
          className="absolute inset-0 w-full h-full object-cover"
          style={{ transform: "scaleX(-1)" }}
          playsInline
          muted
          data-testid="scanner-video"
        />
        <canvas
          ref={canvasRef}
          width={640}
          height={480}
          className="absolute inset-0 w-full h-full pointer-events-none"
          style={{ transform: "scaleX(-1)" }}
        />
        {/* Laser sweep */}
        <div className="laser-line" style={{ top: "0%" }} />

        {/* Status ribbon top */}
        <div className="absolute top-3 left-3 right-3 flex items-center justify-between z-20">
          <div className="flex items-center gap-2">
            <span className={`status-dot ${faceDetected ? "" : "off"}`}></span>
            <span className="tag-eyebrow text-white/80">
              {ready ? (faceDetected ? "WAJAH TERDETEKSI" : "MENUNGGU WAJAH") : "INISIALISASI…"}
            </span>
          </div>
          <span className="tag-eyebrow text-white/60 hidden sm:inline">
            MEDIAPIPE · 468-POINT MESH
          </span>
        </div>

        {/* Challenge prompt bottom */}
        <AnimatePresence mode="wait">
          {showChallenges && currentMeta && (
            <motion.div
              key={currentChallenge}
              initial={{ y: 40, opacity: 0 }}
              animate={{ y: 0, opacity: 1 }}
              exit={{ y: -40, opacity: 0 }}
              transition={{ duration: 0.35 }}
              className="absolute bottom-4 left-4 right-4 z-20"
            >
              <div className="glass rounded-xl px-5 py-4 flex items-center gap-4">
                <div
                  className="w-12 h-12 flex items-center justify-center rounded-lg"
                  style={{
                    background:
                      "linear-gradient(45deg, #8A2BE2 0%, #0057FF 50%, #00F0FF 100%)",
                    boxShadow: "0 0 20px rgba(0,240,255,0.4)",
                  }}
                >
                  <currentMeta.Icon size={22} className="text-black" />
                </div>
                <div className="flex-1 min-w-0">
                  <div className="text-white font-display font-bold text-xl leading-tight" data-testid="challenge-label">
                    {currentMeta.label}
                  </div>
                  <div className="text-white/60 text-sm">{currentMeta.subtitle}</div>
                </div>
                <div className="hidden sm:block text-right">
                  <div className="tag-eyebrow text-white/70">
                    STEP {currentIdx + 1}/{challenges.length}
                  </div>
                  <div className="data-cell text-cyan_glow">{statusText}</div>
                </div>
              </div>
            </motion.div>
          )}
        </AnimatePresence>

        {/* Progress ring / bar (top-right) */}
        {showChallenges && challenges?.length > 0 && (
          <div className="absolute top-14 right-3 z-20 flex gap-1">
            {challenges.map((c, i) => (
              <div
                key={i}
                className={`h-1.5 w-8 rounded-full ${
                  i < passed.length ? "bg-neon_green shadow-green" : "bg-white/10"
                }`}
              />
            ))}
          </div>
        )}
      </div>

      {/* Small legend */}
      <div className="mt-3 flex items-center justify-center gap-3 flex-wrap">
        <span className="chip on">MESH AKTIF</span>
        <span className={`chip ${faceDetected ? "ok" : ""}`}>
          FACE {faceDetected ? "LOCKED" : "SCANNING"}
        </span>
        <span className="chip">
          {Math.round(progress * 100)}% LIVENESS
        </span>
      </div>
    </div>
  );
}

export { CHALLENGE_META };