import { Canvas, useFrame } from "@react-three/fiber"
import { OrbitControls } from "@react-three/drei"
import { useEffect, useRef, useState, type MutableRefObject } from "react"
import { GLTFLoader } from "three/examples/jsm/loaders/GLTFLoader.js"
import { VRM, VRMLoaderPlugin, VRMUtils } from "@pixiv/three-vrm"
import type { Emotion } from "@/lib/voice/sentiment"

// 3D-Avatar (VRM) mit Lippensync (Mund folgt dem TTS-Audiopegel), automatischem Blinzeln und
// stimmungsabhängiger Mimik. Liest die Live-Werte aus Mutable-Refs (kein Re-Render pro Frame).

type LevelRef = MutableRefObject<{ current: number }>   // audioLevel.current.current = Pegel 0..1
type EmotionRef = MutableRefObject<Emotion>

// Ruhepose (A-Pose) als Basis — VRMs laden sonst in T-Pose (Arme waagerecht).
const REST: Record<string, [number, number, number]> = {
  leftUpperArm: [0, 0, 1.2],
  rightUpperArm: [0, 0, -1.2],
  leftLowerArm: [0, -0.2, 0],
  rightLowerArm: [0, 0.2, 0],
}

function setBone(vrm: VRM, name: string, x: number, y: number, z: number) {
  const b = vrm.humanoid?.getNormalizedBoneNode(name as any)
  if (b) b.rotation.set(x, y, z)
}

function applyRestPose(vrm: VRM) {
  for (const [name, r] of Object.entries(REST)) setBone(vrm, name, r[0], r[1], r[2])
  vrm.humanoid?.update()
}

// Lebendige Idle-Animation: prozedural (kein Animations-File). Über die Ruhepose gelegt:
// Atmung, langsames Wiegen + Gewichtsverlagerung, Umschauen (lookYaw/Pitch), Vorlehnen beim
// Sprechen (lean) und Arm-Mitbewegung. Die Augen (lookAt) hält die useFrame separat auf die Kamera.
function applyIdle(vrm: VRM, t: number, level: number, lookYaw: number, lookPitch: number, lean: number) {
  const breathe = Math.sin(t * 1.7)        // ~0.27 Hz Atmung
  const sway = Math.sin(t * 0.45)          // sanftes Wiegen
  const weight = Math.sin(t * 0.32)        // langsame Gewichtsverlagerung
  const emphasis = Math.min(1, level * 1.4)
  const nod = Math.sin(t * 1.3) * emphasis * 0.06   // Sprech-Nicken

  // Rumpf — Atmung, Wiegen, Gewichtsverlagerung, Vorlehnen beim Sprechen
  setBone(vrm, "hips", 0, weight * 0.045, weight * 0.03)
  setBone(vrm, "spine", breathe * 0.025 + lean * 0.07, sway * 0.022, -weight * 0.03)
  setBone(vrm, "chest", breathe * 0.02 + lean * 0.02, sway * 0.018, 0)
  setBone(vrm, "upperChest", breathe * 0.015, 0, 0)

  // Kopf/Hals — Umschauen (gedriftete Zielwinkel) + Atmung + Sprech-Nicken
  setBone(vrm, "neck", lookPitch * 0.4 + nod * 0.5, lookYaw * 0.4, 0)
  setBone(vrm, "head", lookPitch * 0.6 + nod * 0.5 + Math.sin(t * 0.6) * 0.015,
          lookYaw * 0.6 + Math.sin(t * 0.27) * 0.025, Math.sin(t * 0.5) * 0.02)

  // Arme — Ruhepose + leichtes Pendeln + Gewichtsverlagerung
  const arm = Math.sin(t * 0.8) * 0.035
  setBone(vrm, "leftUpperArm", 0, 0, 1.18 + arm + weight * 0.04)
  setBone(vrm, "rightUpperArm", 0, 0, -1.18 - arm + weight * 0.04)
  setBone(vrm, "leftLowerArm", 0, -0.18 - Math.sin(t * 0.8) * 0.03, 0)
  setBone(vrm, "rightLowerArm", 0, 0.18 + Math.sin(t * 0.8) * 0.03, 0)
}

const EXPRESSIONS = ["happy", "angry", "sad", "surprised", "relaxed"] as const
const EMO_TO_EXPR: Record<Emotion, string | null> = {
  neutral: null, happy: "happy", angry: "angry", sad: "sad", surprised: "surprised", relaxed: "relaxed",
}

function VrmModel({ url, audioLevel, emotion, onError }: {
  url: string; audioLevel: LevelRef; emotion: EmotionRef; onError: (m: string) => void
}) {
  const [vrm, setVrm] = useState<VRM | null>(null)
  const smooth = useRef<Record<string, number>>({})
  const blink = useRef({ t: 0, next: 3, active: 0 })
  // Umschauen (gedriftete Kopf-Zielwinkel) + geglättetes Lehnen beim Sprechen.
  const motion = useRef({ yaw: 0, pitch: 0, tYaw: 0, tPitch: 0, t: 0, next: 2.5, lean: 0 })

  useEffect(() => {
    let disposed = false
    let loaded: VRM | null = null
    const loader = new GLTFLoader()
    loader.register((parser) => new VRMLoaderPlugin(parser))
    loader.load(
      url,
      (gltf) => {
        if (disposed) return
        const v = gltf.userData.vrm as VRM | undefined
        if (!v) { onError("Datei enthält kein gültiges VRM-Modell."); return }
        VRMUtils.removeUnnecessaryVertices(gltf.scene)
        if (v.meta?.metaVersion === "0") VRMUtils.rotateVRM0(v)
        v.scene.rotation.y = Math.PI            // dem Betrachter zuwenden
        applyRestPose(v)                        // T-Pose → entspannte A-Pose (Arme unten)
        loaded = v
        setVrm(v)
      },
      undefined,
      (err) => { console.error("VRM-Load-Fehler:", err); onError("Avatar konnte nicht geladen werden (CORS/URL?).") },
    )
    return () => {
      disposed = true
      if (loaded) VRMUtils.deepDispose(loaded.scene)
      setVrm(null)
    }
  }, [url, onError])

  useFrame((state, delta) => {
    if (!vrm) return
    const target = audioLevel.current?.current ?? 0

    // Blickkontakt: Augen folgen der Kamera (schaut dich an).
    if (vrm.lookAt) vrm.lookAt.target = state.camera

    // Umschauen: alle paar Sekunden neues Kopf-Ziel, sanft hineinlerpen.
    const m = motion.current
    m.t += delta
    if (m.t > m.next) {
      m.tYaw = (Math.random() - 0.5) * 0.5      // ±0.25 rad Gieren
      m.tPitch = (Math.random() - 0.5) * 0.24
      m.t = 0
      m.next = 2.5 + Math.random() * 3.5
    }
    m.yaw += (m.tYaw - m.yaw) * Math.min(1, delta * 1.5)
    m.pitch += (m.tPitch - m.pitch) * Math.min(1, delta * 1.5)
    m.lean += (Math.min(1, target * 1.6) - m.lean) * Math.min(1, delta * 3)

    // Lebendige Idle-/Sprech-Bewegung (über die Ruhepose gelegt).
    applyIdle(vrm, state.clock.elapsedTime, target, m.yaw, m.pitch, m.lean)

    const em = vrm.expressionManager
    if (em) {
      // Lippensync: 'aa' folgt geglättet dem Audiopegel.
      const aa = (smooth.current.aa ?? 0) * 0.4 + target * 0.6
      smooth.current.aa = aa
      em.setValue("aa", aa)

      // Mimik: weich zur Ziel-Expression lerpen.
      const want = EMO_TO_EXPR[emotion.current]
      for (const name of EXPRESSIONS) {
        const tv = want === name ? 0.75 : 0
        const cv = smooth.current[name] ?? 0
        const nv = cv + (tv - cv) * Math.min(1, delta * 4)
        smooth.current[name] = nv
        em.setValue(name, nv)
      }

      // Blinzeln: kurzer Dreieckspuls alle 3–7 s.
      const b = blink.current
      b.t += delta
      if (b.active <= 0 && b.t > b.next) { b.active = 0.16; b.t = 0; b.next = 3 + Math.random() * 4 }
      let blinkVal = 0
      if (b.active > 0) {
        b.active -= delta
        const p = 1 - b.active / 0.16          // 0..1 Fortschritt
        blinkVal = 1 - Math.abs(p - 0.5) * 2   // 0 → 1 → 0
      }
      em.setValue("blink", Math.max(0, blinkVal))
    }
    vrm.update(delta)
  })

  return vrm ? <primitive object={vrm.scene} /> : null
}

export function Avatar3D({ url, audioLevel, emotion }: {
  url: string; audioLevel: LevelRef; emotion: EmotionRef
}) {
  const [err, setErr] = useState<string | null>(null)
  return (
    <div className="relative h-full w-full">
      <Canvas
        camera={{ position: [0, 1.35, 1.25], fov: 30 }}
        gl={{ alpha: true, antialias: true }}
        style={{ background: "transparent" }}
      >
        <ambientLight intensity={0.85} />
        <directionalLight position={[1, 2, 2]} intensity={1.1} />
        <directionalLight position={[-1, 1, -1]} intensity={0.4} />
        {/* key=url → bei Avatarwechsel sauber neu mounten */}
        <VrmModel key={url} url={url} audioLevel={audioLevel} emotion={emotion} onError={setErr} />
        <OrbitControls
          target={[0, 1.3, 0]}
          enablePan={false}
          minDistance={0.7}
          maxDistance={3}
          minPolarAngle={Math.PI / 3}
          maxPolarAngle={Math.PI / 1.8}
        />
      </Canvas>
      {err && (
        <div className="absolute inset-x-0 bottom-3 mx-auto w-fit rounded-md bg-red-500/15 border border-red-500/30 px-3 py-1.5 text-xs text-red-300">
          {err}
        </div>
      )}
    </div>
  )
}