/*
 * Copyright 2019 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "include/core/SkPicture.h"
#include "include/core/SkSurface.h"
#include "include/utils/SkBase64.h"
#include "src/utils/SkJSONWriter.h"
#include "src/utils/SkMultiPictureDocument.h"
#include "tools/SkSharingProc.h"
#include "tools/UrlDataManager.h"
#include "tools/debugger/DebugCanvas.h"

#include <emscripten.h>
#include <emscripten/bind.h>

#if SK_SUPPORT_GPU
#include "include/gpu/GrBackendSurface.h"
#include "include/gpu/GrContext.h"
#include "include/gpu/gl/GrGLInterface.h"
#include "include/gpu/gl/GrGLTypes.h"

#include <GL/gl.h>
#include <emscripten/html5.h>
#endif

using JSColor = int32_t;
using Uint8Array = emscripten::val;

// file signature for SkMultiPictureDocument
// TODO(nifong): make public and include from SkMultiPictureDocument.h
static constexpr char kMultiMagic[] = "Skia Multi-Picture Doc\n\n";

struct SimpleImageInfo {
  int width;
  int height;
  SkColorType colorType;
  SkAlphaType alphaType;
  // Shown in the textual description of the image, and used as a common identifier between
  // the resources tab and the command list.
  // TODO(nifong) make the command list use the resource tab's ids instead of UrlDataManager
  uintptr_t imageAddress;
};

SkImageInfo toSkImageInfo(const SimpleImageInfo& sii) {
  return SkImageInfo::Make(sii.width, sii.height, sii.colorType, sii.alphaType);
}

SimpleImageInfo toSimpleImageInfo(const SkImageInfo& ii, const SkImage* addr) {
  return (SimpleImageInfo){ii.width(), ii.height(), ii.colorType(), ii.alphaType(), (uintptr_t)addr};
}

class SkpDebugPlayer {
  public:
    SkpDebugPlayer() :
    udm(UrlDataManager(SkString("/data"))){}

    /* loadSkp deserializes a skp file that has been copied into the shared WASM memory.
     * cptr - a pointer to the data to deserialize.
     * length - length of the data in bytes.
     * The caller must allocate the memory with M._malloc where M is the wasm module in javascript
     * and copy the data into M.buffer at the pointer returned by malloc.
     *
     * uintptr_t is used here because emscripten will not allow binding of functions with pointers
     * to primitive types. We can instead pass a number and cast it to whatever kind of
     * pointer we're expecting.
     */
    void loadSkp(uintptr_t cptr, int length) {
      const uint8_t* data = reinterpret_cast<const uint8_t*>(cptr);
      char magic[8];
      // Both traditional and multi-frame skp files have a magic word
      SkMemoryStream stream(data, length);
      SkDebugf("make stream at %p, with %d bytes\n",data, length);
      // Why -1? I think it's got to do with using a constexpr, just a guess.
      const size_t magicsize = sizeof(kMultiMagic) - 1;
      if (memcmp(data, kMultiMagic, magicsize) == 0) {
        SkDebugf("Try reading as a multi-frame skp\n");
        loadMultiFrame(&stream);
      } else {
        SkDebugf("Try reading as single-frame skp\n");
        frames.push_back(loadSingleFrame(&stream));
      }
    }

    /* drawTo asks the debug canvas to draw from the beginning of the picture
     * to the given command and flush the canvas.
     */
    void drawTo(SkSurface* surface, int32_t index) {
      int cmdlen = frames[fp]->getSize();
      if (cmdlen == 0) {
        SkDebugf("Zero commands to execute");
        return;
      }
      if (index >= cmdlen) {
        SkDebugf("Constrained command index (%d) within this frame's length (%d)\n", index, cmdlen);
        index = cmdlen-1;
      }
      frames[fp]->drawTo(surface->getCanvas(), index);
      surface->getCanvas()->flush();
    }

    const SkIRect& getBounds() { return fBounds; }

    // The following three operations apply to every frame because they are overdraw features.
    // There is only one toggle for them on the app, they are global settings.
    void setOverdrawVis(bool on) {
      for (int i=0; i < frames.size(); i++) {
        frames[i]->setOverdrawViz(on);
      }
    }
    void setGpuOpBounds(bool on) {
      for (int i=0; i < frames.size(); i++) {
        frames[i]->setDrawGpuOpBounds(on);
      }
    }
    void setClipVizColor(JSColor color) {
      for (int i=0; i < frames.size(); i++) {
        frames[i]->setClipVizColor(SkColor(color));
      }
    }
    // The two operations below only apply to the current frame, because they concern the command
    // list, which is unique to each frame.
    void deleteCommand(int index) {
      frames[fp]->deleteDrawCommandAt(index);
    }
    void setCommandVisibility(int index, bool visible) {
      frames[fp]->toggleCommand(index, visible);
    }
    int getSize() const {
      return frames[fp]->getSize();
    }
    int getFrameCount() const {
      return frames.size();
    }

    // Return the command list in JSON representation as a string
    std::string jsonCommandList(sk_sp<SkSurface> surface) {
      SkDynamicMemoryWStream stream;
      SkJSONWriter writer(&stream, SkJSONWriter::Mode::kFast);
      writer.beginObject(); // root
      frames[fp]->toJSON(writer, udm, getSize(), surface->getCanvas());
      writer.endObject(); // root
      writer.flush();
      auto skdata = stream.detachAsData();
      // Convert skdata to string_view, which accepts a length
      std::string_view data_view(reinterpret_cast<const char*>(skdata->data()), skdata->size());
      // and string_view to string, which emscripten understands.
      return std::string(data_view);
    }

    // Gets the clip and matrix of the last command drawn
    std::string lastCommandInfo() {
      SkMatrix vm = frames[fp]->getCurrentMatrix();
      SkIRect clip = frames[fp]->getCurrentClip();

      SkDynamicMemoryWStream stream;
      SkJSONWriter writer(&stream, SkJSONWriter::Mode::kFast);
      writer.beginObject(); // root

      writer.appendName("ViewMatrix");
      DrawCommand::MakeJsonMatrix(writer, vm);
      writer.appendName("ClipRect");
      DrawCommand::MakeJsonIRect(writer, clip);

      writer.endObject(); // root
      writer.flush();
      auto skdata = stream.detachAsData();
      // Convert skdata to string_view, which accepts a length
      std::string_view data_view(reinterpret_cast<const char*>(skdata->data()), skdata->size());
      // and string_view to string, which emscripten understands.
      return std::string(data_view);
    }

    void changeFrame(int index) {
      fp = index;
    }

    // Return the png file at the requested index in
    // the skp file's vector of shared images. this is the set of images referred to by the
    // filenames like "\\1" in DrawImage commands.
    // Return type is the PNG data as a base64 encoded string with prepended URI.
    std::string getImageResource(int index) {
      sk_sp<SkData> pngData = fImages[index]->encodeToData();
      size_t len = SkBase64::Encode(pngData->data(), pngData->size(), nullptr);
      SkString dst;
      dst.resize(len);
      SkBase64::Encode(pngData->data(), pngData->size(), dst.writable_str());
      dst.prepend("data:image/png;base64,");
      return std::string(dst.c_str());
    }

    int getImageCount() {
      return fImages.size();
    }

    // Get the image info of one of the resource images.
    SimpleImageInfo getImageInfo(int index) {
      return toSimpleImageInfo(fImages[index]->imageInfo(), fImages[index].get());
    }

  private:

      // Loads a single frame (traditional) skp file from the provided data stream and returns
      // a newly allocated DebugCanvas initialized with the SkPicture that was in the file.
      std::unique_ptr<DebugCanvas> loadSingleFrame(SkMemoryStream* stream) {
        // note overloaded = operator that actually does a move
        sk_sp<SkPicture> picture = SkPicture::MakeFromStream(stream);
        if (!picture) {
          SkDebugf("Unable to deserialze frame.\n");
          return nullptr;
        }
        SkDebugf("Parsed SKP file.\n");
        // Make debug canvas using bounds from SkPicture
        fBounds = picture->cullRect().roundOut();
        std::unique_ptr<DebugCanvas> debugDanvas = std::make_unique<DebugCanvas>(fBounds);
        SkDebugf("DebugCanvas created.\n");

        // Only draw picture to the debug canvas once.
        debugDanvas->drawPicture(picture);
        SkDebugf("Added picture with %d commands.\n", debugDanvas->getSize());
        return debugDanvas;
      }

      void loadMultiFrame(SkMemoryStream* stream) {

          // Attempt to deserialize with an image sharing serial proc.
          auto deserialContext = std::make_unique<SkSharingDeserialContext>();
          SkDeserialProcs procs;
          procs.fImageProc = SkSharingDeserialContext::deserializeImage;
          procs.fImageCtx = deserialContext.get();

          int page_count = SkMultiPictureDocumentReadPageCount(stream);
          if (!page_count) {
            SkDebugf("Not a MultiPictureDocument");
            return;
          }
          SkDebugf("Expecting %d frames\n", page_count);

          std::vector<SkDocumentPage> pages(page_count);
          if (!SkMultiPictureDocumentRead(stream, pages.data(), page_count, &procs)) {
            SkDebugf("Reading frames from MultiPictureDocument failed");
            return;
          }

          for (const auto& page : pages) {
            // Make debug canvas using bounds from SkPicture
            fBounds = page.fPicture->cullRect().roundOut();
            std::unique_ptr<DebugCanvas> debugDanvas = std::make_unique<DebugCanvas>(fBounds);
            // Only draw picture to the debug canvas once.
            debugDanvas->drawPicture(page.fPicture);
            SkDebugf("Added picture with %d commands.\n", debugDanvas->getSize());

            if (debugDanvas->getSize() <=0 ){
              SkDebugf("Skipped corrupted frame, had %d commands \n", debugDanvas->getSize());
              continue;
            }
            debugDanvas->setOverdrawViz(false);
            debugDanvas->setDrawGpuOpBounds(false);
            debugDanvas->setClipVizColor(SK_ColorTRANSPARENT);
            frames.push_back(std::move(debugDanvas));
          }
          fImages = deserialContext->fImages;
      }

      // A vector of DebugCanvas, each one initialized to a frame of the animation.
      std::vector<std::unique_ptr<DebugCanvas>> frames;
      // The index of the current frame (into the vector above)
      int fp = 0;
      // The width and height of the animation. (in practice the bounds of the last loaded frame)
      SkIRect fBounds;
      // SKP version of loaded file.
      uint32_t fFileVersion;
      // image resources from a loaded file
      std::vector<sk_sp<SkImage>> fImages;

      // The URLDataManager here is a cache that accepts encoded data (pngs) and puts
      // numbers on them. We have our own collection of images (fImages) that was populated by the
      // SkSharingDeserialContext when mskp files are loaded. It would be nice to have the mapping
      // indices between these two caches so the urls displayed in command info match the list
      // in the resource tab, and to make cross linking possible. One way to do this would be to
      // look up all of fImages in udm but the exact encoding of the PNG differs and we wouldn't
      // find anything. TODO(nifong): Unify these two numbering schemes in CollatingCanvas.
      UrlDataManager udm;

};

#if SK_SUPPORT_GPU
sk_sp<GrContext> MakeGrContext(EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context)
{
    EMSCRIPTEN_RESULT r = emscripten_webgl_make_context_current(context);
    if (r < 0) {
        SkDebugf("failed to make webgl context current %d\n", r);
        return nullptr;
    }
    // setup GrContext
    auto interface = GrGLMakeNativeInterface();
    // setup contexts
    sk_sp<GrContext> grContext(GrContext::MakeGL(interface));
    return grContext;
}

sk_sp<SkSurface> MakeOnScreenGLSurface(sk_sp<GrContext> grContext, int width, int height) {
    glClearColor(0, 0, 0, 0);
    glClearStencil(0);
    glClear(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);


    // Wrap the frame buffer object attached to the screen in a Skia render
    // target so Skia can render to it
    GrGLint buffer;
    glGetIntegerv(GL_FRAMEBUFFER_BINDING, &buffer);
    GrGLFramebufferInfo info;
    info.fFBOID = (GrGLuint) buffer;
    SkColorType colorType;

    info.fFormat = GL_RGBA8;
    colorType = kRGBA_8888_SkColorType;

    GrBackendRenderTarget target(width, height, 0, 8, info);

    sk_sp<SkSurface> surface(SkSurface::MakeFromBackendRenderTarget(grContext.get(), target,
                                                                    kBottomLeft_GrSurfaceOrigin,
                                                                    colorType, nullptr, nullptr));
    return surface;
}

sk_sp<SkSurface> MakeRenderTarget(sk_sp<GrContext> grContext, int width, int height) {
    SkImageInfo info = SkImageInfo::MakeN32(width, height, SkAlphaType::kPremul_SkAlphaType);

    sk_sp<SkSurface> surface(SkSurface::MakeRenderTarget(grContext.get(),
                             SkBudgeted::kYes,
                             info, 0,
                             kBottomLeft_GrSurfaceOrigin,
                             nullptr, true));
    return surface;
}

sk_sp<SkSurface> MakeRenderTarget(sk_sp<GrContext> grContext, SimpleImageInfo sii) {
    sk_sp<SkSurface> surface(SkSurface::MakeRenderTarget(grContext.get(),
                             SkBudgeted::kYes,
                             toSkImageInfo(sii), 0,
                             kBottomLeft_GrSurfaceOrigin,
                             nullptr, true));
    return surface;
}
#endif

using namespace emscripten;
EMSCRIPTEN_BINDINGS(my_module) {

  // The main class that the JavaScript in index.html uses
  class_<SkpDebugPlayer>("SkpDebugPlayer")
    .constructor<>()
    .function("loadSkp",              &SkpDebugPlayer::loadSkp, allow_raw_pointers())
    .function("drawTo",               &SkpDebugPlayer::drawTo, allow_raw_pointers())
    .function("getBounds",            &SkpDebugPlayer::getBounds)
    .function("setOverdrawVis",       &SkpDebugPlayer::setOverdrawVis)
    .function("setClipVizColor",      &SkpDebugPlayer::setClipVizColor)
    .function("getSize",              &SkpDebugPlayer::getSize)
    .function("deleteCommand",        &SkpDebugPlayer::deleteCommand)
    .function("setCommandVisibility", &SkpDebugPlayer::setCommandVisibility)
    .function("setGpuOpBounds",       &SkpDebugPlayer::setGpuOpBounds)
    .function("jsonCommandList",      &SkpDebugPlayer::jsonCommandList, allow_raw_pointers())
    .function("lastCommandInfo",      &SkpDebugPlayer::lastCommandInfo)
    .function("changeFrame",          &SkpDebugPlayer::changeFrame)
    .function("getFrameCount",        &SkpDebugPlayer::getFrameCount)
    .function("getImageResource",     &SkpDebugPlayer::getImageResource)
    .function("getImageCount",        &SkpDebugPlayer::getImageCount)
    .function("getImageInfo",         &SkpDebugPlayer::getImageInfo);

  // Structs used as arguments or returns to the functions above
  value_object<SkIRect>("SkIRect")
      .field("fLeft",   &SkIRect::fLeft)
      .field("fTop",    &SkIRect::fTop)
      .field("fRight",  &SkIRect::fRight)
      .field("fBottom", &SkIRect::fBottom);

  // Symbols needed by cpu.js to perform surface creation and flushing.
  enum_<SkColorType>("ColorType")
    .value("RGBA_8888", SkColorType::kRGBA_8888_SkColorType);
  enum_<SkAlphaType>("AlphaType")
      .value("Opaque",   SkAlphaType::kOpaque_SkAlphaType)
      .value("Premul",   SkAlphaType::kPremul_SkAlphaType)
      .value("Unpremul", SkAlphaType::kUnpremul_SkAlphaType);
  value_object<SimpleImageInfo>("SkImageInfo")
    .field("width",     &SimpleImageInfo::width)
    .field("height",    &SimpleImageInfo::height)
    .field("colorType", &SimpleImageInfo::colorType)
    .field("alphaType", &SimpleImageInfo::alphaType)
    .field("imageAddress", &SimpleImageInfo::imageAddress);
  constant("TRANSPARENT", (JSColor) SK_ColorTRANSPARENT);
  function("_getRasterDirectSurface", optional_override([](const SimpleImageInfo ii,
                                                           uintptr_t /* uint8_t*  */ pPtr,
                                                           size_t rowBytes)->sk_sp<SkSurface> {
    uint8_t* pixels = reinterpret_cast<uint8_t*>(pPtr);
    SkImageInfo imageInfo = toSkImageInfo(ii);
    SkDebugf("Made raster direct surface.\n");
    return SkSurface::MakeRasterDirect(imageInfo, pixels, rowBytes, nullptr);
  }), allow_raw_pointers());
  class_<SkSurface>("SkSurface")
    .smart_ptr<sk_sp<SkSurface>>("sk_sp<SkSurface>")
    .function("width", &SkSurface::width)
    .function("height", &SkSurface::height)
    .function("_flush", select_overload<void()>(&SkSurface::flush))
    .function("getCanvas", &SkSurface::getCanvas, allow_raw_pointers());
  class_<SkCanvas>("SkCanvas")
    .function("clear", optional_override([](SkCanvas& self, JSColor color)->void {
      // JS side gives us a signed int instead of an unsigned int for color
      // Add a optional_override to change it out.
      self.clear(SkColor(color));
    }));

  #if SK_SUPPORT_GPU
    class_<GrContext>("GrContext")
        .smart_ptr<sk_sp<GrContext>>("sk_sp<GrContext>");
    function("currentContext", &emscripten_webgl_get_current_context);
    function("setCurrentContext", &emscripten_webgl_make_context_current);
    function("MakeGrContext", &MakeGrContext);
    function("MakeOnScreenGLSurface", &MakeOnScreenGLSurface);
    function("MakeRenderTarget", select_overload<sk_sp<SkSurface>(
      sk_sp<GrContext>, int, int)>(&MakeRenderTarget));
    function("MakeRenderTarget", select_overload<sk_sp<SkSurface>(
      sk_sp<GrContext>, SimpleImageInfo)>(&MakeRenderTarget));
    constant("gpu", true);
  #endif
}