#include "views/view_information.hpp"

#include "providers/provider.hpp"

#include "utils.hpp"

#include <cstring>
#include <cmath>
#include <filesystem>
#include <span>
#include <vector>

#include <magic.h>


#if defined(__EMX__) || defined (WIN32)
#define MAGIC_PATH_SEPARATOR	";"
#else
#define MAGIC_PATH_SEPARATOR	":"
#endif

namespace hex {

    ViewInformation::ViewInformation(prv::Provider* &dataProvider) : View(), m_dataProvider(dataProvider) {
        View::subscribeEvent(Events::DataChanged, [this](void*) {
           this->m_shouldInvalidate = true;
        });
    }

    ViewInformation::~ViewInformation() {
        View::unsubscribeEvent(Events::DataChanged);
    }

    static float calculateEntropy(std::array<float, 256> &valueCounts, size_t numBytes) {
        float entropy = 0;

        for (u16 i = 0; i < 256; i++) {
            valueCounts[i] /= numBytes;

            if (valueCounts[i] > 0)
                entropy -= (valueCounts[i] * std::log2(valueCounts[i]));
        }

        return entropy / 8;
    }

    void ViewInformation::createView() {
        if (!this->m_windowOpen)
            return;

        if (ImGui::Begin("File Information", &this->m_windowOpen)) {
            ImGui::BeginChild("##scrolling", ImVec2(0, 0), false, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoNav);

            if (this->m_dataProvider != nullptr && this->m_dataProvider->isReadable()) {
                if (this->m_shouldInvalidate) {

                    {
                        std::vector<u8> buffer(512, 0x00);
                        std::memset(this->m_valueCounts.data(), 0x00, this->m_valueCounts.size() * sizeof(u32));
                        this->m_blockEntropy.clear();

                        for (u64 i = 0; i < this->m_dataProvider->getSize(); i += 512) {
                            std::array<float, 256> blockValueCounts = { 0 };
                            this->m_dataProvider->read(i, buffer.data(), std::min(size_t(512), this->m_dataProvider->getSize() - i));

                            for (u16 j = 0; j < 512; j++) {
                                blockValueCounts[buffer[j]]++;
                                this->m_valueCounts[buffer[j]]++;
                            }
                            this->m_blockEntropy.push_back(calculateEntropy(blockValueCounts, 512));
                        }

                        this->m_averageEntropy = calculateEntropy(this->m_valueCounts, this->m_dataProvider->getSize());
                        this->m_highestBlockEntropy = *std::max_element(this->m_blockEntropy.begin(), this->m_blockEntropy.end());
                    }

                    {
                        std::vector<u8> buffer(this->m_dataProvider->getSize(), 0x00);
                        this->m_dataProvider->read(0x00, buffer.data(), buffer.size());

                        this->m_fileDescription.clear();
                        this->m_mimeType.clear();

                        std::string magicFiles;

                        std::error_code error;
                        for (const auto &entry : std::filesystem::directory_iterator("magic", error)) {
                            if (entry.is_regular_file() && entry.path().extension() == ".mgc")
                                magicFiles += entry.path().string() + MAGIC_PATH_SEPARATOR;
                        }

                        if (!error) {
                            magicFiles.pop_back();

                            {
                                magic_t cookie = magic_open(MAGIC_NONE);
                                if (magic_load(cookie, magicFiles.c_str()) == -1)
                                    goto skip_description;

                                this->m_fileDescription = magic_buffer(cookie, buffer.data(), buffer.size());

                                skip_description:

                                magic_close(cookie);
                            }


                            {
                                magic_t cookie = magic_open(MAGIC_MIME);
                                if (magic_load(cookie, magicFiles.c_str()) == -1)
                                    goto skip_mime;

                                this->m_mimeType = magic_buffer(cookie, buffer.data(), buffer.size());

                                skip_mime:

                                magic_close(cookie);
                            }

                        }


                        this->m_shouldInvalidate = false;
                    }
                }

                ImGui::NewLine();

                ImGui::Text("Byte Distribution");
                ImGui::PlotHistogram("##nolabel", this->m_valueCounts.data(), 256, 0, nullptr, FLT_MAX, FLT_MAX, ImVec2(0, 100));

                ImGui::NewLine();
                ImGui::Separator();
                ImGui::NewLine();

                ImGui::Text("Entropy");
                ImGui::PlotLines("##nolabel", this->m_blockEntropy.data(), this->m_blockEntropy.size(), 0, nullptr, FLT_MAX, FLT_MAX, ImVec2(0, 100));

                ImGui::NewLine();

                ImGui::LabelText("Average entropy", "%.8f", this->m_averageEntropy);
                ImGui::LabelText("Highest entropy block", "%.8f", this->m_highestBlockEntropy);

                if (this->m_averageEntropy > 0.83 && this->m_highestBlockEntropy > 0.9) {
                    ImGui::NewLine();
                    ImGui::TextColored(ImVec4(0.92F, 0.25F, 0.2F, 1.0F), "This data is most likely encrypted or compressed!");
                }

                ImGui::NewLine();
                ImGui::Separator();
                ImGui::NewLine();

                if (!this->m_fileDescription.empty()) {
                    ImGui::TextUnformatted("Description:");
                    ImGui::TextWrapped("%s", this->m_fileDescription.c_str());
                    ImGui::NewLine();
                }

                if (!this->m_mimeType.empty()) {
                    ImGui::TextUnformatted("MIME Type:");
                    ImGui::TextWrapped("%s", this->m_mimeType.c_str());
                    ImGui::NewLine();
                }
            }

            ImGui::EndChild();
        }
        ImGui::End();
    }

    void ViewInformation::createMenu() {
        if (ImGui::BeginMenu("View")) {
            ImGui::MenuItem("Entropy View", "", &this->m_windowOpen);
            ImGui::EndMenu();
        }
    }

}