/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include <chrono>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <thread>

#include <benchmark/Benchmark.h>
#include <benchmark/TreeDeserialization.h>
#include <capture/CaptureTree.h>
#include <nlohmann/json.hpp>

namespace facebook::yoga {

using namespace nlohmann;
using namespace std::chrono;

constexpr uint32_t kNumRepetitions = 100;
using SteadyClockDurations =
    std::array<steady_clock::duration, kNumRepetitions>;

static bool inputsMatch(
    float actualWidth,
    float expectedWidth,
    float actualHeight,
    float expectedHeight,
    YGMeasureMode actualWidthMode,
    YGMeasureMode expectedWidthMode,
    YGMeasureMode actualHeightMode,
    YGMeasureMode expectedHeightMode) {
  bool widthsAreUndefined =
      YGFloatIsUndefined(actualWidth) && YGFloatIsUndefined(expectedWidth);
  bool widthsAreEqual = widthsAreUndefined || actualWidth == expectedWidth;
  bool heightsAreUndefined =
      YGFloatIsUndefined(actualHeight) && YGFloatIsUndefined(expectedHeight);
  bool heightsAreEqual = heightsAreUndefined || actualHeight == expectedHeight;

  return widthsAreEqual && heightsAreEqual &&
      actualWidthMode == expectedWidthMode &&
      actualHeightMode == expectedHeightMode;
}

YGSize defaultMeasureFunctionResult() {
  std::cout << "Trying to measure a node that wasn't serialized" << std::endl;
  return {10.0, 10.0};
}

YGSize mockMeasureFunc(
    YGNodeConstRef node,
    float availableWidth,
    YGMeasureMode widthMode,
    float availableHeight,
    YGMeasureMode heightMode) {
  (void)node;
  auto fnsPtr = static_cast<SerializedMeasureFuncMap*>(YGNodeGetContext(node));

  if (fnsPtr == nullptr) {
    return defaultMeasureFunctionResult();
  }

  auto fnsIt = fnsPtr->find(node);
  if (fnsIt == fnsPtr->end()) {
    return defaultMeasureFunctionResult();
  }

  for (auto measureFunc : fnsIt->second) {
    if (inputsMatch(
            availableWidth,
            measureFunc.inputWidth,
            availableHeight,
            measureFunc.inputHeight,
            widthMode,
            measureFunc.widthMode,
            heightMode,
            measureFunc.heightMode)) {
      std::this_thread::sleep_for(
          std::chrono::nanoseconds(measureFunc.durationNs));
      return {measureFunc.outputWidth, measureFunc.outputHeight};
    }
  }

  return defaultMeasureFunctionResult();
}

std::shared_ptr<const YGConfig> buildConfigFromJson(const json& j) {
  json jsonConfig = j["config"];
  std::shared_ptr<YGConfig> config(YGConfigNew(), YGConfigFree);
  for (json::iterator it = jsonConfig.begin(); it != jsonConfig.end(); it++) {
    if (it.key() == "use-web-defaults") {
      YGConfigSetUseWebDefaults(config.get(), it.value());
    } else if (it.key() == "point-scale-factor") {
      YGConfigSetPointScaleFactor(config.get(), it.value());
    } else if (it.key() == "errata") {
      YGConfigSetErrata(config.get(), errataFromString(it.value()));
    } else if (it.key() == "experimental-features") {
      // Experimental features is serialized into an array where the values
      // present indicate that that feature is enabled
      for (json::iterator efIt = it.value().begin(); efIt != it.value().end();
           efIt++) {
        YGConfigSetExperimentalFeatureEnabled(
            config.get(), experimentalFeatureFromString(efIt.value()), true);
      }
    }
  }

  return config;
}

std::string edgeStringFromPropertyName(
    const std::string& key,
    const std::string& propertyName) {
  return key.substr(propertyName.length() + 1);
}

void setStylesFromJson(const json& j, YGNodeRef node) {
  json style = j["style"];
  for (const auto& [key, value] : style.items()) {
    if (key == "flex-direction") {
      YGNodeStyleSetFlexDirection(node, flexDirectionFromString(value));
    } else if (key == "justify-content") {
      YGNodeStyleSetJustifyContent(node, justifyContentFromString(value));
    } else if (key == "align-items") {
      YGNodeStyleSetAlignItems(node, alignFromString(value));
    } else if (key == "align-content") {
      YGNodeStyleSetAlignContent(node, alignFromString(value));
    } else if (key == "align-self") {
      YGNodeStyleSetAlignSelf(node, alignFromString(value));
    } else if (key == "flex-wrap") {
      YGNodeStyleSetFlexWrap(node, wrapFromString(value));
    } else if (key == "overflow") {
      YGNodeStyleSetOverflow(node, overflowFromString(value));
    } else if (key == "display") {
      YGNodeStyleSetDisplay(node, displayFromString(value));
    } else if (key == "position-type") {
      YGNodeStyleSetPositionType(node, positionTypeFromString(value));
    } else if (key == "flex-grow") {
      YGNodeStyleSetFlexGrow(node, value);
    } else if (key == "flex-shrink") {
      YGNodeStyleSetFlexShrink(node, value);
    } else if (key == "flex") {
      YGNodeStyleSetFlex(node, value);
    } else if (key == "flex-basis") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitAuto) {
        YGNodeStyleSetFlexBasisAuto(node);
      } else if (unit == YGUnitPoint) {
        YGNodeStyleSetFlexBasis(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetFlexBasisPercent(node, value["value"]);
      }
    } else if (key.starts_with("position")) {
      YGEdge edge = edgeFromString(edgeStringFromPropertyName(key, "position"));
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetPosition(node, edge, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetPositionPercent(node, edge, value["value"]);
      }
    } else if (key.starts_with("padding")) {
      YGEdge edge = edgeFromString(edgeStringFromPropertyName(key, "padding"));
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetPadding(node, edge, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetPaddingPercent(node, edge, value["value"]);
      }
    } else if (key.starts_with("border")) {
      YGEdge edge = edgeFromString(edgeStringFromPropertyName(key, "border"));
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetBorder(node, edge, value["value"]);
      }
    } else if (key.starts_with("margin")) {
      YGEdge edge = edgeFromString(edgeStringFromPropertyName(key, "margin"));
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetMargin(node, edge, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetMarginPercent(node, edge, value["value"]);
      } else if (unit == YGUnitAuto) {
        YGNodeStyleSetMarginAuto(node, edge);
      }
    } else if (key == "gap") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetGap(node, YGGutterAll, value["value"]);
      }
    } else if (key == "column-gap") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetGap(node, YGGutterColumn, value["value"]);
      }
    } else if (key == "row-gap") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetGap(node, YGGutterRow, value["value"]);
      }
    } else if (key == "height") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitAuto) {
        YGNodeStyleSetHeightAuto(node);
      } else if (unit == YGUnitPoint) {
        YGNodeStyleSetHeight(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetHeightPercent(node, value["value"]);
      }
    } else if (key == "width") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitAuto) {
        YGNodeStyleSetWidthAuto(node);
      } else if (unit == YGUnitPoint) {
        YGNodeStyleSetWidth(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetWidthPercent(node, value["value"]);
      }
    } else if (key == "min-height") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetMinHeight(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetMinHeightPercent(node, value["value"]);
      }
    } else if (key == "min-width") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetMinWidth(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetMinWidthPercent(node, value["value"]);
      }
    } else if (key == "max-height") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetMaxHeight(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetMaxHeightPercent(node, value["value"]);
      }
    } else if (key == "max-width") {
      YGUnit unit = unitFromJson(value);
      if (unit == YGUnitPoint) {
        YGNodeStyleSetMaxWidth(node, value["value"]);
      } else if (unit == YGUnitPercent) {
        YGNodeStyleSetMaxWidthPercent(node, value["value"]);
      }
    }
  }
}

std::shared_ptr<YGNode> buildNodeFromJson(
    const json& j,
    std::shared_ptr<const YGConfig> config,
    std::shared_ptr<SerializedMeasureFuncMap> fns) {
  std::shared_ptr<YGNode> node(YGNodeNewWithConfig(config.get()), YGNodeFree);

  if (!j.contains("node") || j["node"].is_null()) {
    return node;
  }

  json nodeState = j["node"];
  for (json::iterator it = nodeState.begin(); it != nodeState.end(); it++) {
    if (it.key() == "always-forms-containing-block") {
      YGNodeSetAlwaysFormsContainingBlock(node.get(), it.value());
    } else if (it.key() == "measure-funcs") {
      std::vector<SerializedMeasureFunc> vec{};
      for (auto measureFuncJson : it.value()) {
        vec.push_back(serializedMeasureFuncFromJson(measureFuncJson));
      }
      fns->insert(std::make_pair(node.get(), vec));
      YGNodeSetContext(node.get(), it.value().is_null() ? nullptr : fns.get());
      YGNodeSetMeasureFunc(node.get(), mockMeasureFunc);
    }
  }

  return node;
}

std::shared_ptr<YogaNodeAndConfig> buildTreeFromJson(
    const json& j,
    std::shared_ptr<SerializedMeasureFuncMap> fns,
    std::shared_ptr<YogaNodeAndConfig> parent,
    size_t index) {
  auto config = buildConfigFromJson(j);
  auto node = buildNodeFromJson(j, config, fns);
  auto wrapper = std::make_shared<YogaNodeAndConfig>(
      node, config, std::vector<std::shared_ptr<YogaNodeAndConfig>>{});

  if (parent != nullptr) {
    YGNodeInsertChild(parent->node_.get(), node.get(), index);
    parent->children_.push_back(wrapper);
  }

  setStylesFromJson(j, node.get());

  if (j.contains("children")) {
    json children = j["children"];
    size_t childIndex = 0;
    for (const json& child : children) {
      buildTreeFromJson(child, fns, wrapper, childIndex);
      childIndex++;
    }
  }

  return wrapper;
}

BenchmarkResult generateBenchmark(json& capture) {
  auto fns = std::make_shared<SerializedMeasureFuncMap>();

  auto treeCreationBegin = steady_clock::now();
  std::shared_ptr<YogaNodeAndConfig> root =
      buildTreeFromJson(capture["tree"], fns, nullptr, 0 /*index*/);
  auto treeCreationEnd = steady_clock::now();

  json layoutInputs = capture["layout-inputs"];
  float availableWidth = layoutInputs["available-width"];
  float availableHeight = layoutInputs["available-height"];
  YGDirection direction = directionFromString(layoutInputs["owner-direction"]);

  auto layoutBegin = steady_clock::now();
  YGNodeCalculateLayout(
      root->node_.get(), availableWidth, availableHeight, direction);
  auto layoutEnd = steady_clock::now();

  return BenchmarkResult{
      treeCreationEnd - treeCreationBegin, layoutEnd - layoutBegin};
}

static void printBenchmarkResult(
    const std::string& name,
    SteadyClockDurations& durations) {
  std::array<double, kNumRepetitions> timesInMs{};
  double mean = 0;
  for (uint32_t i = 0; i < kNumRepetitions; i++) {
    auto ms = duration<double, std::milli>(durations[i]).count();
    timesInMs[i] = ms;
    mean += ms;
  }
  mean /= kNumRepetitions;

  std::sort(timesInMs.begin(), timesInMs.end());
  double median = timesInMs[kNumRepetitions / 2];

  double variance = 0;
  for (uint32_t i = 0; i < kNumRepetitions; i++) {
    variance += std::pow(timesInMs[i] - mean, 2);
  }
  variance /= kNumRepetitions;
  double stddev = std::sqrt(variance);

  printf("%s: median: %lf ms, stddev: %lf ms\n", name.c_str(), median, stddev);
}

void benchmark(std::filesystem::path& capturesDir) {
  for (auto& capture : std::filesystem::directory_iterator(capturesDir)) {
    if (capture.is_directory() || capture.path().extension() != ".json") {
      continue;
    }

    SteadyClockDurations treeCreationDurations;
    SteadyClockDurations layoutDurations;
    SteadyClockDurations totalDurations;

    std::ifstream captureFile(capture.path());
    json j = json::parse(captureFile);
    std::string captureName = capture.path().stem().string();

    std::cout << "Starting benchmark for " << captureName << std::endl;
    for (uint32_t i = 0; i < kNumRepetitions; i++) {
      BenchmarkResult result = generateBenchmark(j);
      treeCreationDurations[i] = result.treeCreationDuration;
      layoutDurations[i] = result.layoutDuration;
      totalDurations[i] = result.treeCreationDuration + result.layoutDuration;
    }

    printBenchmarkResult(captureName + " tree creation", treeCreationDurations);
    printBenchmarkResult(captureName + " layout", layoutDurations);
    printBenchmarkResult(captureName + " total", totalDurations);

    std::cout << std::endl;
  }
}

} // namespace facebook::yoga

int main(int argc, char* argv[]) {
  if (argc == 2) {
    std::filesystem::path capturesDir = argv[argc - 1];
    facebook::yoga::benchmark(capturesDir);
  } else {
    throw std::invalid_argument("Expecting a path as an argument");
    return 1;
  }

  return 0;
}
