/*
 * Copyright 2022 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef skgpu_graphite_KeyContext_DEFINED
#define skgpu_graphite_KeyContext_DEFINED

#include "include/core/SkImageInfo.h"
#include "include/core/SkM44.h"
#include "include/core/SkMatrix.h"
#include "include/private/SkColorData.h"
#include "src/core/SkColorSpaceXformSteps.h"
#include "src/gpu/graphite/TextureProxy.h"

namespace skgpu::graphite {

class Caps;
enum class DstReadRequirement;
class Recorder;
class RuntimeEffectDictionary;
class ShaderCodeDictionary;

// The key context must always be able to provide a valid ShaderCodeDictionary and
// SkRuntimeEffectDictionary. Depending on the calling context it can also supply a
// backend-specific resource providing object (e.g., a Recorder).
class KeyContext {
public:
    enum class OptimizeSampling : bool { kNo = false, kYes = true };
    // Constructor for the pre-compile code path (i.e., no Recorder)
    KeyContext(const Caps* caps,
               ShaderCodeDictionary* dict,
               RuntimeEffectDictionary* rtEffectDict,
               const SkColorInfo& dstColorInfo,
               sk_sp<TextureProxy> dstTexture,
               SkIPoint dstOffset)
            : fDictionary(dict)
            , fRTEffectDict(rtEffectDict)
            , fDstColorInfo(dstColorInfo)
            , fCaps(caps)
            , fDstTexture(std::move(dstTexture))
            , fDstOffset(dstOffset) {}

    // Constructor for the ExtractPaintData code path (i.e., with a Recorder)
    KeyContext(Recorder*,
               const SkM44& local2Dev,
               const SkColorInfo& dstColorInfo,
               OptimizeSampling optimizeSampling,
               const SkColor4f& paintColor,
               sk_sp<TextureProxy> dstTexture,
               SkIPoint dstOffset);

    KeyContext(const KeyContext&);

    Recorder* recorder() const { return fRecorder; }

    const Caps* caps() const { return fCaps; }

    const SkM44& local2Dev() const { return fLocal2Dev; }
    const SkMatrix* localMatrix() const { return fLocalMatrix; }

    ShaderCodeDictionary* dict() const { return fDictionary; }
    RuntimeEffectDictionary* rtEffectDict() const { return fRTEffectDict; }

    const SkColorInfo& dstColorInfo() const { return fDstColorInfo; }

    // Proxy to the destination texture, if it needs to be read from, or null otherwise.
    sk_sp<TextureProxy> dstTexture() const { return fDstTexture; }
    // Offset within dstTexture to the top-left corner of the area that needs to be read.
    SkIPoint dstOffset() const { return fDstOffset; }

    const SkPMColor4f& paintColor() const { return fPaintColor; }

    enum class Scope {
        kDefault,
        kRuntimeEffect,
    };

    Scope scope() const { return fScope; }
    OptimizeSampling optimizeSampling() const { return fOptimizeSampling; }

protected:
    Recorder* fRecorder = nullptr;
    SkM44 fLocal2Dev;
    SkMatrix* fLocalMatrix = nullptr;
    ShaderCodeDictionary* fDictionary;
    RuntimeEffectDictionary* fRTEffectDict;
    SkColorInfo fDstColorInfo;
    // Although stored as premul the paint color is actually comprised of an opaque RGB portion
    // and a separate alpha portion. The two portions will never be used together but are stored
    // together to reduce the number of uniforms.
    SkPMColor4f fPaintColor = SK_PMColor4fBLACK;
    Scope fScope = Scope::kDefault;
    OptimizeSampling fOptimizeSampling = OptimizeSampling::kNo;

private:
    const Caps* fCaps = nullptr;
    sk_sp<TextureProxy> fDstTexture;
    SkIPoint fDstOffset;
};

class KeyContextWithLocalMatrix : public KeyContext {
public:
    KeyContextWithLocalMatrix(const KeyContext& other, const SkMatrix& childLM)
            : KeyContext(other) {
        if (fLocalMatrix) {
            fStorage = SkMatrix::Concat(childLM, *fLocalMatrix);
        } else {
            fStorage = childLM;
        }

        fLocalMatrix = &fStorage;
    }

private:
    KeyContextWithLocalMatrix(const KeyContextWithLocalMatrix&) = delete;
    KeyContextWithLocalMatrix& operator=(const KeyContextWithLocalMatrix&) = delete;

    SkMatrix fStorage;
};

class KeyContextWithColorInfo : public KeyContext {
public:
    KeyContextWithColorInfo(const KeyContext& other, const SkColorInfo& info) : KeyContext(other) {
        // We want to keep fPaintColor's alpha value but replace the RGB with values in the new
        // color space
        SkPMColor4f tmp = fPaintColor;
        tmp.fA = 1.0f;
        SkColorSpaceXformSteps(fDstColorInfo, info).apply(tmp.vec());
        fPaintColor.fR = tmp.fR;
        fPaintColor.fG = tmp.fG;
        fPaintColor.fB = tmp.fB;
        fDstColorInfo = info;
    }

private:
    KeyContextWithColorInfo(const KeyContextWithColorInfo&) = delete;
    KeyContextWithColorInfo& operator=(const KeyContextWithColorInfo&) = delete;
};

class KeyContextWithScope : public KeyContext {
public:
    KeyContextWithScope(const KeyContext& other, KeyContext::Scope scope) : KeyContext(other) {
        fScope = scope;
        // We skip optimized sampling for runtime effects because these might have arbitrary
        // coordinate sampling.
        if (fScope == Scope::kRuntimeEffect) {
            fOptimizeSampling = OptimizeSampling::kNo;
        }
    }

private:
    KeyContextWithScope(const KeyContextWithScope&) = delete;
    KeyContextWithScope& operator=(const KeyContextWithScope&) = delete;
};

class KeyContextWithCoordClamp : public KeyContext {
public:
    KeyContextWithCoordClamp(const KeyContext& other) : KeyContext(other) {
        // Subtlies in clampling implmentation can lead to texture samples at non pixel aligned
        // coordinates.
        fOptimizeSampling = OptimizeSampling::kNo;
    }

private:
    KeyContextWithCoordClamp(const KeyContextWithScope&) = delete;
    KeyContextWithCoordClamp& operator=(const KeyContextWithScope&) = delete;
};

} // namespace skgpu::graphite

#endif // skgpu_graphite_KeyContext_DEFINED