import Resource from '../resource'

class Texture {
  static createTexture2D (gl, img) {
    let tex = gl.createTexture()
    gl.bindTexture(gl.TEXTURE_2D, tex)
    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true)
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, img)

    gl.generateMipmap(gl.TEXTURE_2D)
    gl.bindTexture(gl.TEXTURE_2D, null)

    let oTex = new Texture()
    oTex.type = gl.TEXTURE_2D
    oTex.id = tex

    return oTex
  }
}

class Material {
  async loadTextures (gl) {
    if (this.textures) {
      for (let ti in this.textures) {
        let tex = this.textures[ti]
        if (!(tex instanceof Texture)) {
          let teximg = await Resource.loadImage(tex)
          let result = Texture.createTexture2D(gl, teximg)
          this.textures[ti] = result
        }
      }
    }
  }

  apply (gl, shader) {
    // TODO: lighting related things

    // Load textures
    if (!this.textures || !this.textures.length) return
    for (let i in this.textures) {
      let tex = this.textures[i]
      if (tex && tex instanceof Texture) {
        gl.bindTexture(tex.type, tex.id)
        gl.activeTexture(gl.TEXTURE0 + parseInt(i))
      }
    }
  }
}

export { Texture, Material }