/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "GrGLBuffer.h"
#include "GrGLGpu.h"
#include "GrGpuResourcePriv.h"
#include "SkTraceMemoryDump.h"

#define GL_CALL(X) GR_GL_CALL(this->glGpu()->glInterface(), X)
#define GL_CALL_RET(RET, X) GR_GL_CALL_RET(this->glGpu()->glInterface(), RET, X)

#if GR_GL_CHECK_ALLOC_WITH_GET_ERROR
    #define CLEAR_ERROR_BEFORE_ALLOC(iface)   GrGLClearErr(iface)
    #define GL_ALLOC_CALL(iface, call)        GR_GL_CALL_NOERRCHECK(iface, call)
    #define CHECK_ALLOC_ERROR(iface)          GR_GL_GET_ERROR(iface)
#else
    #define CLEAR_ERROR_BEFORE_ALLOC(iface)
    #define GL_ALLOC_CALL(iface, call)        GR_GL_CALL(iface, call)
    #define CHECK_ALLOC_ERROR(iface)          GR_GL_NO_ERROR
#endif

#ifdef SK_DEBUG
#define VALIDATE() this->validate()
#else
#define VALIDATE() do {} while(false)
#endif

sk_sp<GrGLBuffer> GrGLBuffer::Make(GrGLGpu* gpu, size_t size, GrGpuBufferType intendedType,
                                   GrAccessPattern accessPattern, const void* data) {
    if (gpu->glCaps().transferBufferType() == GrGLCaps::kNone_TransferBufferType &&
        (GrGpuBufferType::kXferCpuToGpu == intendedType ||
         GrGpuBufferType::kXferGpuToCpu == intendedType)) {
        return nullptr;
    }

    sk_sp<GrGLBuffer> buffer(new GrGLBuffer(gpu, size, intendedType, accessPattern, data));
    if (0 == buffer->bufferID()) {
        return nullptr;
    }
    return buffer;
}

// GL_STREAM_DRAW triggers an optimization in Chromium's GPU process where a client's vertex buffer
// objects are implemented as client-side-arrays on tile-deferred architectures.
#define DYNAMIC_DRAW_PARAM GR_GL_STREAM_DRAW

inline static GrGLenum gr_to_gl_access_pattern(GrGpuBufferType bufferType,
                                               GrAccessPattern accessPattern) {
    auto drawUsage = [](GrAccessPattern pattern) {
        switch (pattern) {
            case kDynamic_GrAccessPattern:
                // TODO: Do we really want to use STREAM_DRAW here on non-Chromium?
                return DYNAMIC_DRAW_PARAM;
            case kStatic_GrAccessPattern:
                return GR_GL_STATIC_DRAW;
            case kStream_GrAccessPattern:
                return GR_GL_STREAM_DRAW;
        }
        SK_ABORT("Unexpected access pattern");
        return GR_GL_STATIC_DRAW;
    };

    auto readUsage = [](GrAccessPattern pattern) {
        switch (pattern) {
            case kDynamic_GrAccessPattern:
                return GR_GL_DYNAMIC_READ;
            case kStatic_GrAccessPattern:
                return GR_GL_STATIC_READ;
            case kStream_GrAccessPattern:
                return GR_GL_STREAM_READ;
        }
        SK_ABORT("Unexpected access pattern");
        return GR_GL_STATIC_READ;
    };

    auto usageType = [&drawUsage, &readUsage](GrGpuBufferType type, GrAccessPattern pattern) {
        switch (type) {
            case GrGpuBufferType::kVertex:
            case GrGpuBufferType::kIndex:
            case GrGpuBufferType::kXferCpuToGpu:
                return drawUsage(pattern);
            case GrGpuBufferType::kXferGpuToCpu:
                return readUsage(pattern);
        }
        SK_ABORT("Unexpected gpu buffer type.");
        return GR_GL_STATIC_DRAW;
    };

    return usageType(bufferType, accessPattern);
}

GrGLBuffer::GrGLBuffer(GrGLGpu* gpu, size_t size, GrGpuBufferType intendedType,
                       GrAccessPattern accessPattern, const void* data)
        : INHERITED(gpu, size, intendedType, accessPattern)
        , fIntendedType(intendedType)
        , fBufferID(0)
        , fUsage(gr_to_gl_access_pattern(intendedType, accessPattern))
        , fGLSizeInBytes(0)
        , fHasAttachedToTexture(false) {
    GL_CALL(GenBuffers(1, &fBufferID));
    if (fBufferID) {
        GrGLenum target = gpu->bindBuffer(fIntendedType, this);
        CLEAR_ERROR_BEFORE_ALLOC(gpu->glInterface());
        // make sure driver can allocate memory for this buffer
        GL_ALLOC_CALL(gpu->glInterface(), BufferData(target,
                                                     (GrGLsizeiptr) size,
                                                     data,
                                                     fUsage));
        if (CHECK_ALLOC_ERROR(gpu->glInterface()) != GR_GL_NO_ERROR) {
            GL_CALL(DeleteBuffers(1, &fBufferID));
            fBufferID = 0;
        } else {
            fGLSizeInBytes = size;
        }
    }
    VALIDATE();
    this->registerWithCache(SkBudgeted::kYes);
    if (!fBufferID) {
        this->resourcePriv().removeScratchKey();
    }
}

inline GrGLGpu* GrGLBuffer::glGpu() const {
    SkASSERT(!this->wasDestroyed());
    return static_cast<GrGLGpu*>(this->getGpu());
}

inline const GrGLCaps& GrGLBuffer::glCaps() const {
    return this->glGpu()->glCaps();
}

void GrGLBuffer::onRelease() {
    if (!this->wasDestroyed()) {
        VALIDATE();
        // make sure we've not been abandoned or already released
        if (fBufferID) {
            GL_CALL(DeleteBuffers(1, &fBufferID));
            fBufferID = 0;
            fGLSizeInBytes = 0;
        }
        fMapPtr = nullptr;
        VALIDATE();
    }

    INHERITED::onRelease();
}

void GrGLBuffer::onAbandon() {
    fBufferID = 0;
    fGLSizeInBytes = 0;
    fMapPtr = nullptr;
    VALIDATE();
    INHERITED::onAbandon();
}

void GrGLBuffer::onMap() {
    SkASSERT(fBufferID);
    if (this->wasDestroyed()) {
        return;
    }

    VALIDATE();
    SkASSERT(!this->isMapped());

    // TODO: Make this a function parameter.
    bool readOnly = (GrGpuBufferType::kXferGpuToCpu == fIntendedType);

    // Handling dirty context is done in the bindBuffer call
    switch (this->glCaps().mapBufferType()) {
        case GrGLCaps::kNone_MapBufferType:
            break;
        case GrGLCaps::kMapBuffer_MapBufferType: {
            GrGLenum target = this->glGpu()->bindBuffer(fIntendedType, this);
            // Let driver know it can discard the old data
            if (this->glCaps().useBufferDataNullHint() || fGLSizeInBytes != this->size()) {
                GL_CALL(BufferData(target, this->size(), nullptr, fUsage));
            }
            GL_CALL_RET(fMapPtr, MapBuffer(target, readOnly ? GR_GL_READ_ONLY : GR_GL_WRITE_ONLY));
            break;
        }
        case GrGLCaps::kMapBufferRange_MapBufferType: {
            GrGLenum target = this->glGpu()->bindBuffer(fIntendedType, this);
            // Make sure the GL buffer size agrees with fDesc before mapping.
            if (fGLSizeInBytes != this->size()) {
                GL_CALL(BufferData(target, this->size(), nullptr, fUsage));
            }
            GrGLbitfield writeAccess = GR_GL_MAP_WRITE_BIT;
            if (GrGpuBufferType::kXferCpuToGpu != fIntendedType) {
                // TODO: Make this a function parameter.
                writeAccess |= GR_GL_MAP_INVALIDATE_BUFFER_BIT;
            }
            GL_CALL_RET(fMapPtr, MapBufferRange(target, 0, this->size(),
                                                readOnly ? GR_GL_MAP_READ_BIT : writeAccess));
            break;
        }
        case GrGLCaps::kChromium_MapBufferType: {
            GrGLenum target = this->glGpu()->bindBuffer(fIntendedType, this);
            // Make sure the GL buffer size agrees with fDesc before mapping.
            if (fGLSizeInBytes != this->size()) {
                GL_CALL(BufferData(target, this->size(), nullptr, fUsage));
            }
            GL_CALL_RET(fMapPtr, MapBufferSubData(target, 0, this->size(),
                                                  readOnly ? GR_GL_READ_ONLY : GR_GL_WRITE_ONLY));
            break;
        }
    }
    fGLSizeInBytes = this->size();
    VALIDATE();
}

void GrGLBuffer::onUnmap() {
    SkASSERT(fBufferID);
    if (this->wasDestroyed()) {
        return;
    }

    VALIDATE();
    SkASSERT(this->isMapped());
    if (0 == fBufferID) {
        fMapPtr = nullptr;
        return;
    }
    // bind buffer handles the dirty context
    switch (this->glCaps().mapBufferType()) {
        case GrGLCaps::kNone_MapBufferType:
            SkDEBUGFAIL("Shouldn't get here.");
            return;
        case GrGLCaps::kMapBuffer_MapBufferType: // fall through
        case GrGLCaps::kMapBufferRange_MapBufferType: {
            GrGLenum target = this->glGpu()->bindBuffer(fIntendedType, this);
            GL_CALL(UnmapBuffer(target));
            break;
        }
        case GrGLCaps::kChromium_MapBufferType:
            this->glGpu()->bindBuffer(fIntendedType, this); // TODO: Is this needed?
            GL_CALL(UnmapBufferSubData(fMapPtr));
            break;
    }
    fMapPtr = nullptr;
}

bool GrGLBuffer::onUpdateData(const void* src, size_t srcSizeInBytes) {
    SkASSERT(fBufferID);
    if (this->wasDestroyed()) {
        return false;
    }

    SkASSERT(!this->isMapped());
    VALIDATE();
    if (srcSizeInBytes > this->size()) {
        return false;
    }
    SkASSERT(srcSizeInBytes <= this->size());
    // bindbuffer handles dirty context
    GrGLenum target = this->glGpu()->bindBuffer(fIntendedType, this);

    if (this->glCaps().useBufferDataNullHint()) {
        if (this->size() == srcSizeInBytes) {
            GL_CALL(BufferData(target, (GrGLsizeiptr) srcSizeInBytes, src, fUsage));
        } else {
            // Before we call glBufferSubData we give the driver a hint using
            // glBufferData with nullptr. This makes the old buffer contents
            // inaccessible to future draws. The GPU may still be processing
            // draws that reference the old contents. With this hint it can
            // assign a different allocation for the new contents to avoid
            // flushing the gpu past draws consuming the old contents.
            // TODO I think we actually want to try calling bufferData here
            GL_CALL(BufferData(target, this->size(), nullptr, fUsage));
            GL_CALL(BufferSubData(target, 0, (GrGLsizeiptr) srcSizeInBytes, src));
        }
        fGLSizeInBytes = this->size();
    } else {
        // Note that we're cheating on the size here. Currently no methods
        // allow a partial update that preserves contents of non-updated
        // portions of the buffer (map() does a glBufferData(..size, nullptr..))
        GL_CALL(BufferData(target, srcSizeInBytes, src, fUsage));
        fGLSizeInBytes = srcSizeInBytes;
    }
    VALIDATE();
    return true;
}

void GrGLBuffer::setMemoryBacking(SkTraceMemoryDump* traceMemoryDump,
                                       const SkString& dumpName) const {
    SkString buffer_id;
    buffer_id.appendU32(this->bufferID());
    traceMemoryDump->setMemoryBacking(dumpName.c_str(), "gl_buffer",
                                      buffer_id.c_str());
}

#ifdef SK_DEBUG

void GrGLBuffer::validate() const {
    SkASSERT(0 != fBufferID || 0 == fGLSizeInBytes);
    SkASSERT(nullptr == fMapPtr || fGLSizeInBytes <= this->size());
}

#endif