//
// Copyright (c) 2013 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// This class contains prototypes for representing GLES 3 Vertex Array Objects:
//
//   The buffer objects that are to be used by the vertex stage of the GL are collected
//   together to form a vertex array object. All state related to the definition of data used
//   by the vertex processor is encapsulated in a vertex array object.
//

#ifndef LIBANGLE_VERTEXARRAY_H_
#define LIBANGLE_VERTEXARRAY_H_

#include "libANGLE/Constants.h"
#include "libANGLE/Debug.h"
#include "libANGLE/Observer.h"
#include "libANGLE/RefCountObject.h"
#include "libANGLE/State.h"
#include "libANGLE/VertexAttribute.h"

#include <vector>

namespace rx
{
class GLImplFactory;
class VertexArrayImpl;
}  // namespace rx

namespace gl
{
class Buffer;

class VertexArrayState final : angle::NonCopyable
{
  public:
    VertexArrayState(size_t maxAttribs, size_t maxBindings);
    ~VertexArrayState();

    const std::string &getLabel() const { return mLabel; }

    const BindingPointer<Buffer> &getElementArrayBuffer() const { return mElementArrayBuffer; }
    size_t getMaxAttribs() const { return mVertexAttributes.size(); }
    size_t getMaxBindings() const { return mVertexBindings.size(); }
    const AttributesMask &getEnabledAttributesMask() const { return mEnabledAttributesMask; }
    const std::vector<VertexAttribute> &getVertexAttributes() const { return mVertexAttributes; }
    const VertexAttribute &getVertexAttribute(size_t attribIndex) const
    {
        return mVertexAttributes[attribIndex];
    }
    const std::vector<VertexBinding> &getVertexBindings() const { return mVertexBindings; }
    const VertexBinding &getVertexBinding(size_t bindingIndex) const
    {
        return mVertexBindings[bindingIndex];
    }
    const VertexBinding &getBindingFromAttribIndex(size_t attribIndex) const
    {
        return mVertexBindings[mVertexAttributes[attribIndex].bindingIndex];
    }
    size_t getBindingIndexFromAttribIndex(size_t attribIndex) const
    {
        return mVertexAttributes[attribIndex].bindingIndex;
    }

  private:
    friend class VertexArray;
    std::string mLabel;
    std::vector<VertexAttribute> mVertexAttributes;
    BindingPointer<Buffer> mElementArrayBuffer;
    std::vector<VertexBinding> mVertexBindings;
    AttributesMask mEnabledAttributesMask;
    ComponentTypeMask mVertexAttributesTypeMask;
};

class VertexArray final : public angle::ObserverInterface, public LabeledObject
{
  public:
    VertexArray(rx::GLImplFactory *factory, GLuint id, size_t maxAttribs, size_t maxAttribBindings);

    void onDestroy(const Context *context);

    GLuint id() const;

    void setLabel(const std::string &label) override;
    const std::string &getLabel() const override;

    const VertexBinding &getVertexBinding(size_t bindingIndex) const;
    const VertexAttribute &getVertexAttribute(size_t attribIndex) const;
    const VertexBinding &getBindingFromAttribIndex(size_t attribIndex) const
    {
        return mState.getBindingFromAttribIndex(attribIndex);
    }

    void detachBuffer(const Context *context, GLuint bufferName);
    void setVertexAttribDivisor(const Context *context, size_t index, GLuint divisor);
    void enableAttribute(size_t attribIndex, bool enabledState);
    void setVertexAttribPointer(const Context *context,
                                size_t attribIndex,
                                Buffer *boundBuffer,
                                GLint size,
                                GLenum type,
                                bool normalized,
                                bool pureInteger,
                                GLsizei stride,
                                const void *pointer);
    void setVertexAttribFormat(size_t attribIndex,
                               GLint size,
                               GLenum type,
                               bool normalized,
                               bool pureInteger,
                               GLuint relativeOffset);
    void bindVertexBuffer(const Context *context,
                          size_t bindingIndex,
                          Buffer *boundBuffer,
                          GLintptr offset,
                          GLsizei stride);
    void setVertexAttribBinding(const Context *context, size_t attribIndex, GLuint bindingIndex);
    void setVertexBindingDivisor(size_t bindingIndex, GLuint divisor);
    void setVertexAttribFormatImpl(size_t attribIndex,
                                   GLint size,
                                   GLenum type,
                                   bool normalized,
                                   bool pureInteger,
                                   GLuint relativeOffset);
    void bindVertexBufferImpl(const Context *context,
                              size_t bindingIndex,
                              Buffer *boundBuffer,
                              GLintptr offset,
                              GLsizei stride);

    void setElementArrayBuffer(const Context *context, Buffer *buffer);

    const BindingPointer<Buffer> &getElementArrayBuffer() const
    {
        return mState.getElementArrayBuffer();
    }
    size_t getMaxAttribs() const { return mState.getMaxAttribs(); }
    size_t getMaxBindings() const { return mState.getMaxBindings(); }

    const std::vector<VertexAttribute> &getVertexAttributes() const
    {
        return mState.getVertexAttributes();
    }
    const std::vector<VertexBinding> &getVertexBindings() const
    {
        return mState.getVertexBindings();
    }

    rx::VertexArrayImpl *getImplementation() const { return mVertexArray; }

    const AttributesMask &getEnabledAttributesMask() const
    {
        return mState.getEnabledAttributesMask();
    }

    // Observer implementation
    void onSubjectStateChange(const gl::Context *context,
                              angle::SubjectIndex index,
                              angle::SubjectMessage message) override;

    // Dirty bits for VertexArrays use a heirarchical design. At the top level, each attribute
    // has a single dirty bit. Then an array of MAX_ATTRIBS dirty bits each has a dirty bit for
    // enabled/pointer/format/binding. Bindings are handled similarly. Note that because the
    // total number of dirty bits is 33, it will not be as fast on a 32-bit machine, which
    // can't support the advanced 64-bit scanning intrinsics. We could consider packing the
    // binding and attribute bits together if this becomes a problem.
    enum DirtyBitType
    {
        DIRTY_BIT_ELEMENT_ARRAY_BUFFER,
        DIRTY_BIT_ELEMENT_ARRAY_BUFFER_DATA,

        // Dirty bits for attributes.
        DIRTY_BIT_ATTRIB_0,
        DIRTY_BIT_ATTRIB_MAX = DIRTY_BIT_ATTRIB_0 + gl::MAX_VERTEX_ATTRIBS,

        // Dirty bits for bindings.
        DIRTY_BIT_BINDING_0   = DIRTY_BIT_ATTRIB_MAX,
        DIRTY_BIT_BINDING_MAX = DIRTY_BIT_BINDING_0 + gl::MAX_VERTEX_ATTRIB_BINDINGS,

        // We keep separate dirty bits for bound buffers whose data changed since last update.
        DIRTY_BIT_BUFFER_DATA_0   = DIRTY_BIT_BINDING_MAX,
        DIRTY_BIT_BUFFER_DATA_MAX = DIRTY_BIT_BUFFER_DATA_0 + gl::MAX_VERTEX_ATTRIB_BINDINGS,

        DIRTY_BIT_UNKNOWN = DIRTY_BIT_BUFFER_DATA_MAX,
        DIRTY_BIT_MAX     = DIRTY_BIT_UNKNOWN,
    };

    // We want to keep the number of dirty bits within 64 to keep iteration times fast.
    static_assert(DIRTY_BIT_MAX <= 64, "Too many vertex array dirty bits.");

    enum DirtyAttribBitType
    {
        DIRTY_ATTRIB_ENABLED,
        DIRTY_ATTRIB_POINTER,
        DIRTY_ATTRIB_FORMAT,
        DIRTY_ATTRIB_BINDING,
        DIRTY_ATTRIB_UNKNOWN,
        DIRTY_ATTRIB_MAX = DIRTY_ATTRIB_UNKNOWN,
    };

    enum DirtyBindingBitType
    {
        DIRTY_BINDING_BUFFER,
        DIRTY_BINDING_DIVISOR,
        DIRTY_BINDING_UNKNOWN,
        DIRTY_BINDING_MAX = DIRTY_BINDING_UNKNOWN,
    };

    using DirtyBits = angle::BitSet<DIRTY_BIT_MAX>;
    using DirtyAttribBits       = angle::BitSet<DIRTY_ATTRIB_MAX>;
    using DirtyBindingBits      = angle::BitSet<DIRTY_BINDING_MAX>;
    using DirtyAttribBitsArray  = std::array<DirtyAttribBits, gl::MAX_VERTEX_ATTRIBS>;
    using DirtyBindingBitsArray = std::array<DirtyBindingBits, gl::MAX_VERTEX_ATTRIB_BINDINGS>;

    static size_t GetVertexIndexFromDirtyBit(size_t dirtyBit);

    gl::Error syncState(const Context *context);
    bool hasAnyDirtyBit() const { return mDirtyBits.any(); }

    ComponentTypeMask getAttributesTypeMask() const { return mState.mVertexAttributesTypeMask; }
    AttributesMask getAttributesMask() const { return mState.mEnabledAttributesMask; }

    void onBindingChanged(bool bound);

  private:
    ~VertexArray() override;

    void setDirtyAttribBit(size_t attribIndex, DirtyAttribBitType dirtyAttribBit);
    void setDirtyBindingBit(size_t bindingIndex, DirtyBindingBitType dirtyBindingBit);

    void updateObserverBinding(size_t bindingIndex);
    DirtyBitType getDirtyBitFromIndex(bool contentsChanged, angle::SubjectIndex index) const;

    GLuint mId;

    VertexArrayState mState;
    DirtyBits mDirtyBits;
    DirtyAttribBitsArray mDirtyAttribBits;
    DirtyBindingBitsArray mDirtyBindingBits;
    Optional<DirtyBits> mDirtyBitsGuard;

    rx::VertexArrayImpl *mVertexArray;

    std::vector<angle::ObserverBinding> mArrayBufferObserverBindings;
    angle::ObserverBinding mElementArrayBufferObserverBinding;
};

}  // namespace gl

#endif // LIBANGLE_VERTEXARRAY_H_
