/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ANDROID_HWUI_PROGRAM_H
#define ANDROID_HWUI_PROGRAM_H

#include <utils/KeyedVector.h>

#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>

#include <SkXfermode.h>

#include "Debug.h"
#include "Matrix.h"
#include "Properties.h"

namespace android {
namespace uirenderer {

///////////////////////////////////////////////////////////////////////////////
// Defines
///////////////////////////////////////////////////////////////////////////////

// Debug
#if DEBUG_PROGRAMS
    #define PROGRAM_LOGD(...) ALOGD(__VA_ARGS__)
#else
    #define PROGRAM_LOGD(...)
#endif

#define COLOR_COMPONENT_THRESHOLD 1.0f
#define COLOR_COMPONENT_INV_THRESHOLD 0.0f

#define PROGRAM_KEY_TEXTURE 0x1
#define PROGRAM_KEY_A8_TEXTURE 0x2
#define PROGRAM_KEY_BITMAP 0x4
#define PROGRAM_KEY_GRADIENT 0x8
#define PROGRAM_KEY_BITMAP_FIRST 0x10
#define PROGRAM_KEY_COLOR_MATRIX 0x20
#define PROGRAM_KEY_COLOR_LIGHTING 0x40
#define PROGRAM_KEY_COLOR_BLEND 0x80
#define PROGRAM_KEY_BITMAP_NPOT 0x100
#define PROGRAM_KEY_SWAP_SRC_DST 0x2000

#define PROGRAM_KEY_BITMAP_WRAPS_MASK 0x600
#define PROGRAM_KEY_BITMAP_WRAPT_MASK 0x1800

// Encode the xfermodes on 6 bits
#define PROGRAM_MAX_XFERMODE 0x1f
#define PROGRAM_XFERMODE_SHADER_SHIFT 26
#define PROGRAM_XFERMODE_COLOR_OP_SHIFT 20
#define PROGRAM_XFERMODE_FRAMEBUFFER_SHIFT 14

#define PROGRAM_BITMAP_WRAPS_SHIFT 9
#define PROGRAM_BITMAP_WRAPT_SHIFT 11

#define PROGRAM_GRADIENT_TYPE_SHIFT 33 // 2 bits for gradient type
#define PROGRAM_MODULATE_SHIFT 35

#define PROGRAM_HAS_AA_SHIFT 36

#define PROGRAM_HAS_EXTERNAL_TEXTURE_SHIFT 37
#define PROGRAM_HAS_TEXTURE_TRANSFORM_SHIFT 38

#define PROGRAM_HAS_GAMMA_CORRECTION 39

#define PROGRAM_IS_SIMPLE_GRADIENT 40

#define PROGRAM_HAS_COLORS 41

#define PROGRAM_HAS_DEBUG_HIGHLIGHT 42
#define PROGRAM_EMULATE_STENCIL 43

///////////////////////////////////////////////////////////////////////////////
// Types
///////////////////////////////////////////////////////////////////////////////

typedef uint64_t programid;

///////////////////////////////////////////////////////////////////////////////
// Program description
///////////////////////////////////////////////////////////////////////////////

/**
 * Describe the features required for a given program. The features
 * determine the generation of both the vertex and fragment shaders.
 * A ProgramDescription must be used in conjunction with a ProgramCache.
 */
struct ProgramDescription {
    enum ColorModifier {
        kColorNone = 0,
        kColorMatrix,
        kColorLighting,
        kColorBlend
    };

    enum Gradient {
        kGradientLinear = 0,
        kGradientCircular,
        kGradientSweep
    };

    ProgramDescription() {
        reset();
    }

    // Texturing
    bool hasTexture;
    bool hasAlpha8Texture;
    bool hasExternalTexture;
    bool hasTextureTransform;

    // Color attribute
    bool hasColors;

    // Modulate, this should only be set when setColor() return true
    bool modulate;

    // Shaders
    bool hasBitmap;
    bool isBitmapNpot;

    bool isAA; // drawing with a per-vertex alpha

    bool hasGradient;
    Gradient gradientType;
    bool isSimpleGradient;

    SkXfermode::Mode shadersMode;

    bool isBitmapFirst;
    GLenum bitmapWrapS;
    GLenum bitmapWrapT;

    // Color operations
    ColorModifier colorOp;
    SkXfermode::Mode colorMode;

    // Framebuffer blending (requires Extensions.hasFramebufferFetch())
    // Ignored for all values < SkXfermode::kPlus_Mode
    SkXfermode::Mode framebufferMode;
    bool swapSrcDst;

    bool hasGammaCorrection;
    float gamma;

    bool hasDebugHighlight;
    bool emulateStencil;

    /**
     * Resets this description. All fields are reset back to the default
     * values they hold after building a new instance.
     */
    void reset() {
        hasTexture = false;
        hasAlpha8Texture = false;
        hasExternalTexture = false;
        hasTextureTransform = false;

        hasColors = false;

        isAA = false;

        modulate = false;

        hasBitmap = false;
        isBitmapNpot = false;

        hasGradient = false;
        gradientType = kGradientLinear;
        isSimpleGradient = false;

        shadersMode = SkXfermode::kClear_Mode;

        isBitmapFirst = false;
        bitmapWrapS = GL_CLAMP_TO_EDGE;
        bitmapWrapT = GL_CLAMP_TO_EDGE;

        colorOp = kColorNone;
        colorMode = SkXfermode::kClear_Mode;

        framebufferMode = SkXfermode::kClear_Mode;
        swapSrcDst = false;

        hasGammaCorrection = false;
        gamma = 2.2f;

        hasDebugHighlight = false;
    }

    /**
     * Indicates, for a given color, whether color modulation is required in
     * the fragment shader. When this method returns true, the program should
     * be provided with a modulation color.
     */
    bool setColorModulate(const float a) {
        modulate = a < COLOR_COMPONENT_THRESHOLD;
        return modulate;
    }

    /**
     * Indicates, for a given color, whether color modulation is required in
     * the fragment shader. When this method returns true, the program should
     * be provided with a modulation color.
     */
    bool setAlpha8ColorModulate(const float r, const float g, const float b, const float a) {
        modulate = a < COLOR_COMPONENT_THRESHOLD || r > COLOR_COMPONENT_INV_THRESHOLD ||
                g > COLOR_COMPONENT_INV_THRESHOLD || b > COLOR_COMPONENT_INV_THRESHOLD;
        return modulate;
    }

    /**
     * Computes the unique key identifying this program.
     */
    programid key() const {
        programid key = 0;
        if (hasTexture) key |= PROGRAM_KEY_TEXTURE;
        if (hasAlpha8Texture) key |= PROGRAM_KEY_A8_TEXTURE;
        if (hasBitmap) {
            key |= PROGRAM_KEY_BITMAP;
            if (isBitmapNpot) {
                key |= PROGRAM_KEY_BITMAP_NPOT;
                key |= getEnumForWrap(bitmapWrapS) << PROGRAM_BITMAP_WRAPS_SHIFT;
                key |= getEnumForWrap(bitmapWrapT) << PROGRAM_BITMAP_WRAPT_SHIFT;
            }
        }
        if (hasGradient) key |= PROGRAM_KEY_GRADIENT;
        key |= programid(gradientType) << PROGRAM_GRADIENT_TYPE_SHIFT;
        if (isBitmapFirst) key |= PROGRAM_KEY_BITMAP_FIRST;
        if (hasBitmap && hasGradient) {
            key |= (shadersMode & PROGRAM_MAX_XFERMODE) << PROGRAM_XFERMODE_SHADER_SHIFT;
        }
        switch (colorOp) {
            case kColorMatrix:
                key |= PROGRAM_KEY_COLOR_MATRIX;
                break;
            case kColorLighting:
                key |= PROGRAM_KEY_COLOR_LIGHTING;
                break;
            case kColorBlend:
                key |= PROGRAM_KEY_COLOR_BLEND;
                key |= (colorMode & PROGRAM_MAX_XFERMODE) << PROGRAM_XFERMODE_COLOR_OP_SHIFT;
                break;
            case kColorNone:
                break;
        }
        key |= (framebufferMode & PROGRAM_MAX_XFERMODE) << PROGRAM_XFERMODE_FRAMEBUFFER_SHIFT;
        if (swapSrcDst) key |= PROGRAM_KEY_SWAP_SRC_DST;
        if (modulate) key |= programid(0x1) << PROGRAM_MODULATE_SHIFT;
        if (isAA) key |= programid(0x1) << PROGRAM_HAS_AA_SHIFT;
        if (hasExternalTexture) key |= programid(0x1) << PROGRAM_HAS_EXTERNAL_TEXTURE_SHIFT;
        if (hasTextureTransform) key |= programid(0x1) << PROGRAM_HAS_TEXTURE_TRANSFORM_SHIFT;
        if (hasGammaCorrection) key |= programid(0x1) << PROGRAM_HAS_GAMMA_CORRECTION;
        if (isSimpleGradient) key |= programid(0x1) << PROGRAM_IS_SIMPLE_GRADIENT;
        if (hasColors) key |= programid(0x1) << PROGRAM_HAS_COLORS;
        if (hasDebugHighlight) key |= programid(0x1) << PROGRAM_HAS_DEBUG_HIGHLIGHT;
        if (emulateStencil) key |= programid(0x1) << PROGRAM_EMULATE_STENCIL;
        return key;
    }

    /**
     * Logs the specified message followed by the key identifying this program.
     */
    void log(const char* message) const {
#if DEBUG_PROGRAMS
        programid k = key();
        PROGRAM_LOGD("%s (key = 0x%.8x%.8x)", message, uint32_t(k >> 32),
                uint32_t(k & 0xffffffff));
#endif
    }

private:
    static inline uint32_t getEnumForWrap(GLenum wrap) {
        switch (wrap) {
            case GL_CLAMP_TO_EDGE:
                return 0;
            case GL_REPEAT:
                return 1;
            case GL_MIRRORED_REPEAT:
                return 2;
        }
        return 0;
    }

}; // struct ProgramDescription

/**
 * A program holds a vertex and a fragment shader. It offers several utility
 * methods to query attributes and uniforms.
 */
class Program {
public:
    enum ShaderBindings {
        kBindingPosition,
        kBindingTexCoords
    };

    /**
     * Creates a new program with the specified vertex and fragment
     * shaders sources.
     */
    Program(const ProgramDescription& description, const char* vertex, const char* fragment);
    virtual ~Program();

    /**
     * Binds this program to the GL context.
     */
    virtual void use();

    /**
     * Marks this program as unused. This will not unbind
     * the program from the GL context.
     */
    virtual void remove();

    /**
     * Returns the OpenGL name of the specified attribute.
     */
    int getAttrib(const char* name);

    /**
     * Returns the OpenGL name of the specified uniform.
     */
    int getUniform(const char* name);

    /**
     * Indicates whether this program is currently in use with
     * the GL context.
     */
    inline bool isInUse() const {
        return mUse;
    }

    /**
     * Indicates whether this program was correctly compiled and linked.
     */
    inline bool isInitialized() const {
        return mInitialized;
    }

    /**
     * Binds the program with the specified projection, modelView and
     * transform matrices.
     */
    void set(const mat4& projectionMatrix, const mat4& modelViewMatrix,
             const mat4& transformMatrix, bool offset = false);

    /**
     * Sets the color associated with this shader.
     */
    void setColor(const float r, const float g, const float b, const float a);

    /**
     * Name of the position attribute.
     */
    int position;

    /**
     * Name of the texCoords attribute if it exists, -1 otherwise.
     */
    int texCoords;

    /**
     * Name of the transform uniform.
     */
    int transform;

    /**
     * Name of the projection uniform.
     */
    int projection;

protected:
    /**
     * Adds an attribute with the specified name.
     *
     * @return The OpenGL name of the attribute.
     */
    int addAttrib(const char* name);

    /**
     * Binds the specified attribute name to the specified slot.
     */
    int bindAttrib(const char* name, ShaderBindings bindingSlot);

    /**
     * Adds a uniform with the specified name.
     *
     * @return The OpenGL name of the uniform.
     */
    int addUniform(const char* name);

private:
    /**
     * Compiles the specified shader of the specified type.
     *
     * @return The name of the compiled shader.
     */
    GLuint buildShader(const char* source, GLenum type);

    // Name of the OpenGL program and shaders
    GLuint mProgramId;
    GLuint mVertexShader;
    GLuint mFragmentShader;

    // Keeps track of attributes and uniforms slots
    KeyedVector<const char*, int> mAttributes;
    KeyedVector<const char*, int> mUniforms;

    bool mUse;
    bool mInitialized;

    // Uniforms caching
    bool mHasColorUniform;
    int mColorUniform;

    bool mHasSampler;

    mat4 mProjection;
    bool mOffset;
}; // class Program

}; // namespace uirenderer
}; // namespace android

#endif // ANDROID_HWUI_PROGRAM_H