package com.xscm.moduleutil.widget


import android.graphics.SurfaceTexture
import android.opengl.GLES20
import android.opengl.Matrix

class ChannelSplitRenderer {

    private val vertexShaderCode = """
        attribute vec4 aPosition;
        attribute vec2 aTexCoord;
        varying vec2 vTexCoord;
        void main() {
            gl_Position = aPosition;
            vTexCoord = aTexCoord;
        }
    """

    private val fragmentShaderCode = """
    precision mediump float;
    uniform sampler2D uTexture;
    varying vec2 vTexCoord;
    void main() {
        // 只使用左半部分作为最终颜色
        vec2 leftCoord = vec2(vTexCoord.x * 0.5, vTexCoord.y);
        vec4 color = texture2D(uTexture, leftCoord);

        // 设置 alpha 为 1.0 表示完全不透明，或根据需求设为 0.0 表示全透明
        gl_FragColor = vec4(color.rgb, 0.0); // 左通道颜色 + 不透明
    }"""

    private var program = 0
    private var positionHandle = 0
    private var texCoordHandle = 0
    private var textureHandle = 0
    private val projectionMatrix = FloatArray(16)
    private val modelMatrix = FloatArray(16)

    fun onSurfaceCreated(surface: SurfaceTexture, width: Int, height: Int) {
        // 初始化着色器
        val vertexShader = ShaderUtils.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode)
        val fragmentShader = ShaderUtils.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode)

        program = GLES20.glCreateProgram().also {
            GLES20.glAttachShader(it, vertexShader)
            GLES20.glAttachShader(it, fragmentShader)
            GLES20.glLinkProgram(it)
        }

        positionHandle = GLES20.glGetAttribLocation(program, "aPosition")
        texCoordHandle = GLES20.glGetAttribLocation(program, "aTexCoord")
        textureHandle = GLES20.glGetUniformLocation(program, "uTexture")

        // 初始化矩阵
        Matrix.setIdentityM(projectionMatrix, 0)
        Matrix.setIdentityM(modelMatrix, 0)

        GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f)
        GLES20.glEnable(GLES20.GL_BLEND)
        GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA)
    }

    fun onSurfaceChanged(width: Int, height: Int) {
        GLES20.glViewport(0, 0, width, height)
    }

    fun onDrawFrame(textureId: Int) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT)
        GLES20.glUseProgram(program)

        // 定义顶点坐标（全屏）
        val vertices = floatArrayOf(
            -1.0f, -1.0f, 0.0f,
            1.0f, -1.0f, 0.0f,
            -1.0f,  1.0f, 0.0f,
            1.0f,  1.0f, 0.0f
        )

        // 修改纹理坐标，只映射左半部分视频内容到左侧屏幕
        val texCoords = floatArrayOf(
            0.0f, 1.0f,   // 左下角
            0.5f, 1.0f,   // 右下角（对应视频中间）
            0.0f, 0.0f,   // 左上角
            0.5f, 0.0f    // 右上角
        )

        val vertexBuffer = ShaderUtils.createFloatBuffer(vertices)
        val texBuffer = ShaderUtils.createFloatBuffer(texCoords)

        GLES20.glEnableVertexAttribArray(positionHandle)
        GLES20.glVertexAttribPointer(
            positionHandle, 3,
            GLES20.GL_FLOAT, false,
            0, vertexBuffer
        )

        GLES20.glEnableVertexAttribArray(texCoordHandle)
        GLES20.glVertexAttribPointer(
            texCoordHandle, 2,
            GLES20.GL_FLOAT, false,
            0, texBuffer
        )

        // 绑定纹理
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0)
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId)
        GLES20.glUniform1i(textureHandle, 0)

        // 绘制
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4)

        // 清理
        GLES20.glDisableVertexAttribArray(positionHandle)
        GLES20.glDisableVertexAttribArray(texCoordHandle)
    }


    fun release() {
        GLES20.glDeleteProgram(program)
    }
}