// Haupt-Einstiegspunkt: Scene/Camera/Renderer, Licht, Welt, Spieler, Loop.
import * as THREE from 'three';
import { EffectComposer } from 'three/addons/postprocessing/EffectComposer.js';
import { RenderPass } from 'three/addons/postprocessing/RenderPass.js';
import { UnrealBloomPass } from 'three/addons/postprocessing/UnrealBloomPass.js';
import { OutputPass } from 'three/addons/postprocessing/OutputPass.js';
import {
  BLOCK, BIOME, HOTBAR, BLOCK_COLOR,
} from './constants.js';
import {
  RENDER_DISTANCE, MAX_OPS_PER_FRAME, MAX_PIXEL_RATIO,
  ANTIALIAS, MSAA_SAMPLES, TONE_MAPPING, TONE_MAPPING_EXPOSURE,
  SKY_COLOR, FOG_NEAR, FOG_FAR,
  CAMERA_FOV, CAMERA_NEAR, CAMERA_FAR,
  HEMISPHERE, SUN, SUN_DIRECTION,
  SHADOWS_ENABLED, SHADOW_MAP_SIZE, SHADOW_AREA, SHADOW_BIAS, SHADOW_NORMAL_BIAS,
  BLOOM_ENABLED, BLOOM,
  PLAYER, SPAWN, REACH,
} from './config.js';
import { buildAtlasTexture } from './textures.js';
import { World } from './world.js';
import { Player } from './player.js';
import { Input } from './input.js';
import { raycastVoxel } from './raycast.js';
import { getBiome } from './worldgen.js';

const BIOME_NAME = { [BIOME.PLAINS]: 'Plains', [BIOME.FOREST]: 'Wald', [BIOME.DESERT]: 'Wüste' };

// ---------- Renderer / Scene / Camera ----------
const canvas = document.createElement('canvas');
document.body.appendChild(canvas);
const renderer = new THREE.WebGLRenderer({ canvas, antialias: ANTIALIAS });
renderer.setPixelRatio(Math.min(window.devicePixelRatio, MAX_PIXEL_RATIO));
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.outputColorSpace = THREE.SRGBColorSpace;
renderer.shadowMap.enabled = SHADOWS_ENABLED;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
renderer.toneMapping = TONE_MAPPING;
renderer.toneMappingExposure = TONE_MAPPING_EXPOSURE;

const scene = new THREE.Scene();
scene.background = new THREE.Color(SKY_COLOR);
scene.fog = new THREE.Fog(SKY_COLOR, FOG_NEAR, FOG_FAR);

const camera = new THREE.PerspectiveCamera(CAMERA_FOV, window.innerWidth / window.innerHeight, CAMERA_NEAR, CAMERA_FAR);
camera.rotation.order = 'YXZ';

// ---------- Licht ----------
const hemi = new THREE.HemisphereLight(HEMISPHERE.sky, HEMISPHERE.ground, HEMISPHERE.intensity);
scene.add(hemi);
const sun = new THREE.DirectionalLight(SUN.color, SUN.intensity);
// Schattenwerfer: orthografische Shadow-Camera, die pro Frame dem Spieler folgt
// (kleines Frustum -> hohe Texeldichte + performant, da ferne Chunks cullt).
sun.castShadow = SHADOWS_ENABLED;
sun.shadow.mapSize.set(SHADOW_MAP_SIZE, SHADOW_MAP_SIZE);
sun.shadow.camera.near = 1;
sun.shadow.camera.far = 260;
// halbe Kantenlaenge (Welt-Einheiten) um den Spieler = SHADOW_AREA aus config
sun.shadow.camera.left = -SHADOW_AREA;
sun.shadow.camera.right = SHADOW_AREA;
sun.shadow.camera.top = SHADOW_AREA;
sun.shadow.camera.bottom = -SHADOW_AREA;
sun.shadow.bias = SHADOW_BIAS;
sun.shadow.normalBias = SHADOW_NORMAL_BIAS;
scene.add(sun);
scene.add(sun.target);
// Konstanter Richtungs-Offset; Position/Target werden in der Loop ans Spieler-Auge gesetzt.
const SUN_DIR = new THREE.Vector3(...SUN_DIRECTION).normalize();
const _sunOffset = SUN_DIR.clone().multiplyScalar(120);

// ---------- Texturen & Materialien ----------
// vertexColors aktiviert: der Mesher liefert pro Vertex einen AO-Wert (Grau-
// stufe), der in den Beleuchtungsterm multipliziert wird -> "Smooth Lighting".
const atlas = buildAtlasTexture();
const matOpaque = new THREE.MeshLambertMaterial({ map: atlas, vertexColors: true });
const matWater = new THREE.MeshLambertMaterial({
  map: atlas, vertexColors: true, transparent: true, depthWrite: false, side: THREE.DoubleSide,
});

// ---------- Post-Processing ----------
// EffectComposer: RenderPass -> UnrealBloomPass (subtiler Glanz auf hellen
// Flaechen) -> OutputPass (wendet renderer.toneMapping=ACES + sRGB an).
// HalfFloat-Target verhindert Banding im HDR-Bereich; samples=4 aktiviert MSAA,
// da der Composer ansonsten ohne Kantenglaettung in sein Puffer rendert.
const rt = new THREE.WebGLRenderTarget(window.innerWidth, window.innerHeight, {
  type: THREE.HalfFloatType,
});
const composer = new EffectComposer(renderer, rt);
// MSAA auf beiden internen Puffern (WebGL2 erlaubt MSAA auf Float-Targets),
// damit die Szene im Composer kantengeglättet wird. Vorsichtshalber auf beiden
// Targets explizit setzen, falls clone() die Property nicht forterbt.
composer.renderTarget1.samples = MSAA_SAMPLES;
composer.renderTarget2.samples = MSAA_SAMPLES;
composer.addPass(new RenderPass(scene, camera));
const bloom = new UnrealBloomPass(
  new THREE.Vector2(window.innerWidth, window.innerHeight),
  BLOOM.strength,
  BLOOM.radius,
  BLOOM.threshold,
);
if (BLOOM_ENABLED) composer.addPass(bloom);
composer.addPass(new OutputPass());

// ---------- Welt & Spieler ----------
const world = new World(scene, { opaque: matOpaque, water: matWater });
const player = new Player(world);
const input = new Input(canvas);

// Spawn-Punkt
{
  const sx = SPAWN.x, sz = SPAWN.z;
  const groundY = world.highestSolidY(sx, sz);
  player.setSpawn(sx + 0.5, groundY + 2, sz + 0.5);
}
camera.position.set(player.pos[0], player.pos[1] + PLAYER.EYE, player.pos[2]);

// Vorab die naechsten Chunks um den Spawn bauen (Boden unter den Fuessen ist
// durch highestSolidY ohnehin gesichert; hier geht's nur um den Start-Blick).
for (let i = 0; i < 12; i++) world.updateStreaming(player.pos[0], player.pos[2], RENDER_DISTANCE, MAX_OPS_PER_FRAME);

// ---------- Highlight-Box ----------
const hlGeo = new THREE.BoxGeometry(1.002, 1.002, 1.002);
const hlEdges = new THREE.LineSegments(
  new THREE.EdgesGeometry(hlGeo),
  new THREE.LineBasicMaterial({ color: 0x000000, transparent: true, opacity: 0.5 })
);
hlEdges.visible = false;
scene.add(hlEdges);

// ---------- UI: Hotbar ----------
let selected = 0;
const hotbarEl = document.getElementById('hotbar');
HOTBAR.forEach((block, i) => {
  const slot = document.createElement('div');
  slot.className = 'slot' + (i === 0 ? ' active' : '');
  slot.innerHTML = `<span class="num">${i + 1}</span>`;
  const sw = document.createElement('div');
  sw.className = 'swatch';
  sw.style.background = BLOCK_COLOR[block] || '#888';
  slot.appendChild(sw);
  slot.dataset.index = i;
  hotbarEl.appendChild(slot);
});
function setSelected(i) {
  selected = (i + HOTBAR.length) % HOTBAR.length;
  [...hotbarEl.children].forEach((c, idx) => c.classList.toggle('active', idx === selected));
}

window.addEventListener('keydown', (e) => {
  const m = /^Digit([1-6])$/.exec(e.code);
  if (m) setSelected(parseInt(m[1], 10) - 1);
});

// ---------- Overlay / Pointer-Lock ----------
const overlay = document.getElementById('overlay');
overlay.addEventListener('click', () => {
  overlay.classList.add('hidden');
  input.requestLock();
});
document.addEventListener('pointerlockchange', () => {
  if (!document.pointerLockElement) overlay.classList.remove('hidden');
});

// ---------- Resize ----------
window.addEventListener('resize', () => {
  camera.aspect = window.innerWidth / window.innerHeight;
  camera.updateProjectionMatrix();
  renderer.setSize(window.innerWidth, window.innerHeight);
  composer.setSize(window.innerWidth, window.innerHeight);
});

// ---------- HUD ----------
const hud = document.getElementById('hud');
let fpsAcc = 0, fpsFrames = 0, fps = 0;

// ---------- Hilfsfunktion: Blickrichtung ----------
const _eye = new THREE.Vector3();
function aimDir(out) {
  const cp = Math.cos(player.pitch), sp = Math.sin(player.pitch);
  const sy = Math.sin(player.yaw), cy = Math.cos(player.yaw);
  out.set(-sy * cp, sp, -cy * cp).normalize();
  return out;
}

// Blockplatzierung pruefen: nicht in den Spieler hineinsetzen
function wouldIntersectPlayer(bx, by, bz) {
  const minX = player.pos[0] - PLAYER.HALF, maxX = player.pos[0] + PLAYER.HALF;
  const minY = player.pos[1], maxY = player.pos[1] + PLAYER.HEIGHT;
  const minZ = player.pos[2] - PLAYER.HALF, maxZ = player.pos[2] + PLAYER.HALF;
  return (bx + 1 > minX && bx < maxX &&
          by + 1 > minY && by < maxY &&
          bz + 1 > minZ && bz < maxZ);
}

const _dir = new THREE.Vector3();

// ---------- Game-Loop ----------
let last = performance.now();
function frame(now) {
  const dt = Math.min(0.05, (now - last) / 1000);
  last = now;

  if (input.locked) {
    player.update(input, dt);

    // Kamera nach Spieler
    player.eyePosition(_eye);
    camera.position.copy(_eye);
    camera.rotation.set(player.pitch, player.yaw, 0, 'YXZ');

    // Raycast + Highlight
    aimDir(_dir);
    const hit = raycastVoxel(
      (x, y, z) => world.getBlock(x, y, z),
      camera.position.x, camera.position.y, camera.position.z,
      _dir.x, _dir.y, _dir.z, REACH
    );
    if (hit) {
      hlEdges.visible = true;
      hlEdges.position.set(hit.x + 0.5, hit.y + 0.5, hit.z + 0.5);
    } else {
      hlEdges.visible = false;
    }

    // Interaktion
    if (hit && input.leftClick) {
      if (hit.block !== BLOCK.BEDROCK) {
        world.setBlock(hit.x, hit.y, hit.z, BLOCK.AIR);
      }
    }
    if (hit && input.rightClick) {
      const px = hit.x + hit.nx, py = hit.y + hit.ny, pz = hit.z + hit.nz;
      const cur = world.getBlock(px, py, pz);
      if ((cur === BLOCK.AIR || cur === BLOCK.WATER) && !wouldIntersectPlayer(px, py, pz)) {
        world.setBlock(px, py, pz, HOTBAR[selected]);
      }
    }
  }

  input.endFrame();

  // Streaming (immer, auch im Pause-Menue, damit die Welt laedt)
  world.updateStreaming(player.pos[0], player.pos[2], RENDER_DISTANCE, MAX_OPS_PER_FRAME);

  // Sonne folgt dem Spieler -> Shadow-Frustum bleibt um den Spieler zentriert.
  sun.position.set(
    player.pos[0] + _sunOffset.x, player.pos[1] + _sunOffset.y, player.pos[2] + _sunOffset.z
  );
  sun.target.position.set(player.pos[0], player.pos[1], player.pos[2]);
  sun.target.updateMatrixWorld();

  composer.render();

  // HUD
  fpsAcc += dt; fpsFrames++;
  if (fpsAcc >= 0.5) { fps = Math.round(fpsFrames / fpsAcc); fpsAcc = 0; fpsFrames = 0; }
  const biome = BIOME_NAME[getBiome(Math.floor(player.pos[0]), Math.floor(player.pos[2]))] || '?';
  hud.textContent =
    `FPS ${fps}\n` +
    `XYZ ${player.pos[0].toFixed(1)} / ${player.pos[1].toFixed(1)} / ${player.pos[2].toFixed(1)}\n` +
    `Biome: ${biome}\n` +
    `Modus: ${player.flying ? 'Fliegen' : 'Gehen'}   Block: ${[...Object.entries(BLOCK).find(([,v]) => v === HOTBAR[selected])][0]}`;

  requestAnimationFrame(frame);
}
requestAnimationFrame(frame);