import { buildCamera, type MapScene } from './mapRenderer'
import { TrackLayer } from '../layer/trackLayer'
import { GpsLayer } from '../layer/gpsLayer'

function createShader(gl: any, type: number, source: string): any {
  const shader = gl.createShader(type)
  if (!shader) {
    throw new Error('WebGL shader 创建失败')
  }

  gl.shaderSource(shader, source)
  gl.compileShader(shader)
  if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
    const message = gl.getShaderInfoLog(shader) || 'unknown shader error'
    gl.deleteShader(shader)
    throw new Error(message)
  }

  return shader
}

function createProgram(gl: any, vertexSource: string, fragmentSource: string): any {
  const vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexSource)
  const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentSource)
  const program = gl.createProgram()
  if (!program) {
    throw new Error('WebGL program 创建失败')
  }

  gl.attachShader(program, vertexShader)
  gl.attachShader(program, fragmentShader)
  gl.linkProgram(program)
  gl.deleteShader(vertexShader)
  gl.deleteShader(fragmentShader)

  if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
    const message = gl.getProgramInfoLog(program) || 'unknown program error'
    gl.deleteProgram(program)
    throw new Error(message)
  }

  return program
}

export class WebGLVectorRenderer {
  canvas: any
  gl: any
  dpr: number
  trackLayer: TrackLayer
  gpsLayer: GpsLayer
  program: any
  positionBuffer: any
  colorBuffer: any
  positionLocation: number
  colorLocation: number

  constructor(trackLayer: TrackLayer, gpsLayer: GpsLayer) {
    this.canvas = null
    this.gl = null
    this.dpr = 1
    this.trackLayer = trackLayer
    this.gpsLayer = gpsLayer
    this.program = null
    this.positionBuffer = null
    this.colorBuffer = null
    this.positionLocation = -1
    this.colorLocation = -1
  }

  attachCanvas(canvasNode: any, width: number, height: number, dpr: number): void {
    this.canvas = canvasNode
    this.dpr = dpr || 1
    canvasNode.width = Math.max(1, Math.floor(width * this.dpr))
    canvasNode.height = Math.max(1, Math.floor(height * this.dpr))
    this.attachContext(canvasNode.getContext('webgl') || canvasNode.getContext('experimental-webgl'), canvasNode)
  }

  attachContext(gl: any, canvasNode: any): void {
    if (!gl) {
      throw new Error('当前环境不支持 WebGL Vector Layer')
    }

    this.canvas = canvasNode
    this.gl = gl
    this.program = createProgram(
      gl,
      'attribute vec2 a_position; attribute vec4 a_color; varying vec4 v_color; void main() { gl_Position = vec4(a_position, 0.0, 1.0); v_color = a_color; }',
      'precision mediump float; varying vec4 v_color; void main() { gl_FragColor = v_color; }',
    )
    this.positionBuffer = gl.createBuffer()
    this.colorBuffer = gl.createBuffer()
    this.positionLocation = gl.getAttribLocation(this.program, 'a_position')
    this.colorLocation = gl.getAttribLocation(this.program, 'a_color')

    gl.viewport(0, 0, canvasNode.width, canvasNode.height)
    gl.enable(gl.BLEND)
    gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
  }

  destroy(): void {
    if (this.gl) {
      if (this.program) {
        this.gl.deleteProgram(this.program)
      }
      if (this.positionBuffer) {
        this.gl.deleteBuffer(this.positionBuffer)
      }
      if (this.colorBuffer) {
        this.gl.deleteBuffer(this.colorBuffer)
      }
    }

    this.program = null
    this.positionBuffer = null
    this.colorBuffer = null
    this.gl = null
    this.canvas = null
  }

  render(scene: MapScene, pulseFrame: number): void {
    if (!this.gl || !this.program || !this.positionBuffer || !this.colorBuffer || !this.canvas) {
      return
    }

    const gl = this.gl
    const camera = buildCamera(scene)
    const trackPoints = this.trackLayer.projectPoints(scene, camera)
    const gpsPoint = this.gpsLayer.projectPoint(scene, camera)
    const positions: number[] = []
    const colors: number[] = []

    for (let index = 1; index < trackPoints.length; index += 1) {
      this.pushSegment(positions, colors, trackPoints[index - 1], trackPoints[index], 6, [0.09, 0.43, 0.36, 0.96], scene)
    }

    for (const point of trackPoints) {
      this.pushCircle(positions, colors, point.x, point.y, 10, [0.09, 0.43, 0.36, 1], scene)
      this.pushCircle(positions, colors, point.x, point.y, 6.5, [0.97, 0.98, 0.95, 1], scene)
    }

    this.pushCircle(positions, colors, gpsPoint.x, gpsPoint.y, this.gpsLayer.getPulseRadius(pulseFrame), [0.13, 0.62, 0.74, 0.22], scene)
    this.pushCircle(positions, colors, gpsPoint.x, gpsPoint.y, 13, [1, 1, 1, 0.95], scene)
    this.pushCircle(positions, colors, gpsPoint.x, gpsPoint.y, 9, [0.13, 0.63, 0.74, 1], scene)

    gl.viewport(0, 0, this.canvas.width, this.canvas.height)
    gl.useProgram(this.program)

    gl.bindBuffer(gl.ARRAY_BUFFER, this.positionBuffer)
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STREAM_DRAW)
    gl.enableVertexAttribArray(this.positionLocation)
    gl.vertexAttribPointer(this.positionLocation, 2, gl.FLOAT, false, 0, 0)

    gl.bindBuffer(gl.ARRAY_BUFFER, this.colorBuffer)
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STREAM_DRAW)
    gl.enableVertexAttribArray(this.colorLocation)
    gl.vertexAttribPointer(this.colorLocation, 4, gl.FLOAT, false, 0, 0)

    gl.drawArrays(gl.TRIANGLES, 0, positions.length / 2)
  }

  pushSegment(
    positions: number[],
    colors: number[],
    start: { x: number; y: number },
    end: { x: number; y: number },
    width: number,
    color: [number, number, number, number],
    scene: MapScene,
  ): void {
    const deltaX = end.x - start.x
    const deltaY = end.y - start.y
    const length = Math.sqrt(deltaX * deltaX + deltaY * deltaY)
    if (!length) {
      return
    }

    const normalX = -deltaY / length * (width / 2)
    const normalY = deltaX / length * (width / 2)
    const topLeft = this.toClip(start.x + normalX, start.y + normalY, scene)
    const topRight = this.toClip(end.x + normalX, end.y + normalY, scene)
    const bottomLeft = this.toClip(start.x - normalX, start.y - normalY, scene)
    const bottomRight = this.toClip(end.x - normalX, end.y - normalY, scene)

    this.pushTriangle(positions, colors, topLeft, topRight, bottomLeft, color)
    this.pushTriangle(positions, colors, bottomLeft, topRight, bottomRight, color)
  }

  pushCircle(
    positions: number[],
    colors: number[],
    centerX: number,
    centerY: number,
    radius: number,
    color: [number, number, number, number],
    scene: MapScene,
  ): void {
    const segments = 20
    const center = this.toClip(centerX, centerY, scene)
    for (let index = 0; index < segments; index += 1) {
      const startAngle = index / segments * Math.PI * 2
      const endAngle = (index + 1) / segments * Math.PI * 2
      const start = this.toClip(centerX + Math.cos(startAngle) * radius, centerY + Math.sin(startAngle) * radius, scene)
      const end = this.toClip(centerX + Math.cos(endAngle) * radius, centerY + Math.sin(endAngle) * radius, scene)
      this.pushTriangle(positions, colors, center, start, end, color)
    }
  }

  pushTriangle(
    positions: number[],
    colors: number[],
    first: { x: number; y: number },
    second: { x: number; y: number },
    third: { x: number; y: number },
    color: [number, number, number, number],
  ): void {
    positions.push(first.x, first.y, second.x, second.y, third.x, third.y)
    for (let index = 0; index < 3; index += 1) {
      colors.push(color[0], color[1], color[2], color[3])
    }
  }

  toClip(x: number, y: number, scene: MapScene): { x: number; y: number } {
    const previewScale = scene.previewScale || 1
    const originX = scene.previewOriginX || scene.viewportWidth / 2
    const originY = scene.previewOriginY || scene.viewportHeight / 2
    const scaledX = originX + (x - originX) * previewScale
    const scaledY = originY + (y - originY) * previewScale

    return {
      x: scaledX / scene.viewportWidth * 2 - 1,
      y: 1 - scaledY / scene.viewportHeight * 2,
    }
  }
}