import { RenderConfig } from "../engine/render/RenderConfig"
import { RenderScene, type RenderInstance } from "../engine/render/RenderScene"
import { Camera } from "../engine/scene/Camera"
import {
  CharacterController,
  type CharacterInput,
} from "../engine/world/CharacterController"
import { Level } from "../engine/world/Level"
import { loadTextures } from "./assets"
import { buildLevel } from "../game/level"
import { Player, type Player as PlayerState } from "../game/player"
import { createRenderer } from "./renderer"

const FOV_DEGREES = 75
const FOV = (FOV_DEGREES * Math.PI) / 180

const screen = document.querySelector<HTMLCanvasElement>("#screen")!
const ctx = screen.getContext("2d")!
const fpsEl = document.querySelector<HTMLDivElement>("#fps")!

/** Deterministic flythrough (virtual time from frame index), so the st and mt
 *  bench runs render the exact same work. Deliberately stands *inside* the dense
 *  tree ring (radius ~40–100) and sweeps a full 360° yaw so the frame is filled
 *  with forest -- the heavy case that quantizes to 30fps, not the empty clearing. */
function benchCamera(tv: number): Camera {
  const drift = tv * 0.12
  const radius = 65 + 30 * Math.sin(tv * 0.25)
  return {
    position: {
      x: Math.cos(drift) * radius,
      y: 3,
      z: Math.sin(drift) * radius,
    },
    yaw: tv * 0.7,
    pitch: 0.05 * Math.sin(tv * 0.5),
    fov: FOV,
  }
}

function round2(n: number): number {
  return Math.round(n * 100) / 100
}

function benchStats(a: number[]): {
  median: number
  p95: number
  max: number
  mean: number
} {
  const s = a.toSorted((x, y) => x - y)
  const q = (p: number): number =>
    s[Math.min(s.length - 1, Math.floor(p * s.length))]
  return {
    median: round2(q(0.5)),
    p95: round2(q(0.95)),
    max: round2(s[s.length - 1]),
    mean: round2(a.reduce((x, y) => x + y, 0) / a.length),
  }
}

async function main(): Promise<void> {
  const textures = await loadTextures()
  const level = buildLevel(textures)
  // `?bench=st` / `?bench=mt` runs a scripted flythrough and reports timings.
  const benchMode = new URLSearchParams(globalThis.location.search).get("bench")
  const forceWorkers =
    benchMode === "mt" ? true : benchMode === "st" ? false : undefined

  let config: RenderConfig = RenderConfig.standard
  const renderer = createRenderer(level.render, config, forceWorkers)
  let inFlight = false
  let image = new ImageData(renderer.fb.width, renderer.fb.height)
  let colorBytes = new Uint8ClampedArray(renderer.fb.color.buffer)

  // The canvas backing store IS the internal resolution; the browser/compositor
  // scales the element up (see `layout`). So `present` is one internal-res
  // putImageData with no per-frame window-sized blit on the main thread.
  function retarget(): void {
    const fb = renderer.fb
    screen.width = fb.width
    screen.height = fb.height
    image = new ImageData(fb.width, fb.height)
    colorBytes = new Uint8ClampedArray(fb.color.buffer)
    layout()
  }

  // Size + center the canvas to an integer multiple of the internal res (crisp
  // letterboxed upscale, done by the GPU). Recomputed only on resize/config.
  function layout(): void {
    const fb = renderer.fb
    const scale = Math.max(
      1,
      Math.floor(
        Math.min(
          globalThis.innerWidth / fb.width,
          globalThis.innerHeight / fb.height,
        ),
      ),
    )
    const w = fb.width * scale
    const h = fb.height * scale
    screen.style.width = `${w}px`
    screen.style.height = `${h}px`
    screen.style.left = `${(globalThis.innerWidth - w) >> 1}px`
    screen.style.top = `${(globalThis.innerHeight - h) >> 1}px`
    screen.style.imageRendering =
      config.upscaleFilter === "linear" ? "auto" : "pixelated"
  }
  retarget()

  function useConfig(next: RenderConfig): void {
    config = next
    renderer.reconfigure(next)
    inFlight = false
    retarget()
  }

  function present(): void {
    image.data.set(colorBytes)
    ctx.putImageData(image, 0, 0)
  }

  globalThis.addEventListener("resize", layout)

  if (benchMode) {
    runBench(renderer, level, present, benchMode)
    return
  }

  const player: PlayerState = Player.create()
  const keys = new Set<string>()
  globalThis.addEventListener("keydown", (e) => {
    keys.add(e.code)
    if (e.code === "Digit1") {
      useConfig(RenderConfig.standard)
    }
    if (e.code === "Digit2") {
      useConfig(RenderConfig.soft)
    }
    if (e.code === "Digit3") {
      useConfig(RenderConfig.clean)
    }
  })
  globalThis.addEventListener("keyup", (e) => {
    keys.delete(e.code)
  })
  // Losing focus (alt-tab, pointer-lock exit) drops keyup events, so clear held
  // keys or movement sticks on.
  globalThis.addEventListener("blur", () => {
    keys.clear()
  })
  screen.addEventListener("click", () => {
    screen.requestPointerLock()
  })
  globalThis.addEventListener("mousemove", (e) => {
    if (document.pointerLockElement !== screen) {
      return
    }
    player.yaw += e.movementX * 0.0025
    player.pitch = Math.max(
      -1.4,
      Math.min(1.4, player.pitch - e.movementY * 0.0025),
    )
  })

  // Triangles drawn this frame (room + each visible chunk, LOD-aware) for the HUD.
  function frameTris(
    visible: number[],
    instances: RenderInstance[],
    camera: Camera,
  ): number {
    return RenderScene.triangleCount(
      level.render,
      visible,
      instances,
      camera.position,
      config.lodDistance,
    )
  }

  // Poll-based pump: present the finished frame, dispatch the next; if workers
  // aren't done we skip this vsync (no async/rAF desync). The HUD reports the
  // critical-path budget (work + present) so the real bottleneck is visible.
  let last = performance.now()
  let fpsLast = last
  let fpsFrames = 0
  let workMax = 0
  let presentMax = 0
  let vsyncMax = 0
  let lastPresent = performance.now()
  let lastVisible: number[] = []
  let lastInstances: RenderInstance[] = []
  let lastCamera: Camera = {
    position: { x: 0, y: 0, z: 0 },
    yaw: 0,
    pitch: 0,
    fov: FOV,
  }

  function show(): void {
    const p0 = performance.now()
    present()
    const p1 = performance.now()
    presentMax = Math.max(presentMax, p1 - p0)
    vsyncMax = Math.max(vsyncMax, p1 - lastPresent)
    lastPresent = p1
    workMax = Math.max(workMax, renderer.workMs())
    fpsFrames++
  }

  function tick(): void {
    requestAnimationFrame(tick)
    if (inFlight) {
      if (!renderer.done()) {
        return
      }
      show()
      inFlight = false
    }
    const now = performance.now()
    const dt = Math.min(0.05, (now - last) / 1000)
    last = now
    if (now - fpsLast >= 250) {
      const fps = Math.round((fpsFrames * 1000) / (now - fpsLast))
      const tag = renderer.parallel ? "" : " 1core"
      fpsEl.textContent =
        `${fps} fps${tag}\n` +
        `work ${round2(workMax)} + present ${round2(presentMax)} = ${round2(workMax + presentMax)}ms\n` +
        `vsync ${round2(vsyncMax)}ms · ${lastVisible.length} ch · ${frameTris(lastVisible, lastInstances, lastCamera)} tris`
      fpsLast = now
      fpsFrames = 0
      workMax = 0
      presentMax = 0
      vsyncMax = 0
    }
    Level.update(level, dt)
    Level.refreshActorColliders(level, player.position, Player.actorCollisionRange)
    CharacterController.update(
      player,
      readPlayerInput(keys),
      dt,
      level.collision,
      Player.config,
    )
    const camera: Camera = {
      position: {
        x: player.position.x,
        y: player.position.y + Player.config.eyeHeight,
        z: player.position.z,
      },
      yaw: player.yaw,
      pitch: player.pitch,
      fov: FOV,
    }
    const viewProj = Camera.viewProjection(
      camera,
      renderer.fb.width / renderer.fb.height,
    )
    const visible = RenderScene.visibleChunks(level.render, viewProj)
    const instances = Level.visibleInstances(level, viewProj)
    lastVisible = visible
    lastInstances = instances
    lastCamera = camera
    renderer.dispatch(camera, viewProj, visible, now / 1000, instances)
    inFlight = true
    if (renderer.done()) {
      show()
      inFlight = false
    }
  }
  requestAnimationFrame(tick)
}

/** Scripted flythrough that records critical-path work time and present-to-present
 *  interval, then reports the distributions (exposed on `window.__BENCH__`). */
function runBench(
  renderer: ReturnType<typeof createRenderer>,
  level: ReturnType<typeof buildLevel>,
  present: () => void,
  mode: string,
): void {
  const WARM = 60
  const MEASURE = 300
  const work: number[] = []
  const frame: number[] = []
  let i = 0
  let inFlight = false
  let prev = performance.now()
  let finished = false

  function record(): boolean {
    present()
    const now = performance.now()
    if (i >= WARM) {
      work.push(renderer.workMs())
      frame.push(now - prev)
    }
    prev = now
    inFlight = false
    i++
    return i >= WARM + MEASURE
  }

  function report(): void {
    finished = true
    const result = {
      mode,
      parallel: renderer.parallel,
      cores: (globalThis.navigator as Navigator).hardwareConcurrency,
      coi:
        (globalThis as { crossOriginIsolated?: boolean })
          .crossOriginIsolated === true,
      res: `${renderer.fb.width}x${renderer.fb.height}`,
      workMs: benchStats(work),
      frameMs: benchStats(frame),
    }
    ;(globalThis as { __BENCH__?: unknown }).__BENCH__ = result
    console.log(`BENCH ${JSON.stringify(result)}`)
    fpsEl.textContent = `bench ${mode}: work ${result.workMs.median}ms (p95 ${result.workMs.p95})`
  }

  function tick(): void {
    if (finished) {
      return
    }
    requestAnimationFrame(tick)
    if (inFlight) {
      if (!renderer.done()) {
        return
      }
      if (record()) {
        report()
        return
      }
    }
    Level.update(level, 1 / 60)
    const camera = benchCamera(i / 60)
    const viewProj = Camera.viewProjection(
      camera,
      renderer.fb.width / renderer.fb.height,
    )
    const visible = RenderScene.visibleChunks(level.render, viewProj)
    const instances = Level.visibleInstances(level, viewProj)
    renderer.dispatch(camera, viewProj, visible, i / 60, instances)
    inFlight = true
    if (renderer.done() && record()) {
      report()
    }
  }
  requestAnimationFrame(tick)
}

function readPlayerInput(keys: Set<string>): CharacterInput {
  return {
    forward: (keys.has("KeyW") ? 1 : 0) - (keys.has("KeyS") ? 1 : 0),
    right: (keys.has("KeyD") ? 1 : 0) - (keys.has("KeyA") ? 1 : 0),
    jump: keys.has("Space"),
    run: keys.has("ShiftLeft") || keys.has("ShiftRight"),
  }
}

main().catch((error) => {
  console.error(error)
})