#include "content/views/view_diff.hpp"

#include <hex/api/imhex_api.hpp>

#include <hex/helpers/fmt.hpp>
#include <hex/providers/buffered_reader.hpp>

#include <fonts/codicons_font.h>
#include <wolv/utils/guards.hpp>

namespace hex::plugin::diffing {

    using DifferenceType = ContentRegistry::Diffing::DifferenceType;

    ViewDiff::ViewDiff() : View::Window("hex.diffing.view.diff.name", ICON_VS_DIFF_SIDEBYSIDE) {
        // Clear the selected diff providers when a provider is closed
        EventProviderClosed::subscribe(this, [this](prv::Provider *) {
            for (auto &column : m_columns) {
                column.provider = -1;
                column.hexEditor.setSelectionUnchecked(std::nullopt, std::nullopt);
                column.diffTree.clear();
            }

        });

        // Set the background highlight callbacks for the two hex editor columns
        m_columns[0].hexEditor.setBackgroundHighlightCallback(this->createCompareFunction(1));
        m_columns[1].hexEditor.setBackgroundHighlightCallback(this->createCompareFunction(0));
    }

    ViewDiff::~ViewDiff() {
        EventProviderClosed::unsubscribe(this);
    }

    namespace {

        bool drawDiffColumn(ViewDiff::Column &column, float height) {
            if (height < 0)
                return false;

            bool scrolled = false;
            ImGui::PushID(&column);
            ON_SCOPE_EXIT { ImGui::PopID(); };

            // Draw the hex editor
            float prevScroll = column.hexEditor.getScrollPosition();
            column.hexEditor.draw(height);
            float currScroll = column.hexEditor.getScrollPosition();

            // Check if the user scrolled the hex editor
            if (prevScroll != currScroll) {
                scrolled = true;
                column.scrollLock = 5;
            }

            return scrolled;
        }

        bool drawProviderSelector(ViewDiff::Column &column) {
            bool shouldReanalyze = false;

            ImGui::PushID(&column);

            auto providers = ImHexApi::Provider::getProviders();
            auto &providerIndex = column.provider;

            // Get the name of the currently selected provider
            std::string preview;
            if (ImHexApi::Provider::isValid() && providerIndex >= 0)
                preview = providers[providerIndex]->getName();

            // Draw combobox with all available providers
            ImGui::SetNextItemWidth(ImGui::GetContentRegionAvail().x);
            if (ImGui::BeginCombo("", preview.c_str())) {

                for (size_t i = 0; i < providers.size(); i++) {
                    ImGui::PushID(i + 1);
                    if (ImGui::Selectable(providers[i]->getName().c_str())) {
                        providerIndex = i;
                        shouldReanalyze = true;
                    }
                    ImGui::PopID();
                }

                ImGui::EndCombo();
            }

            ImGui::PopID();

            return shouldReanalyze;
        }

    }

    void ViewDiff::analyze(prv::Provider *providerA, prv::Provider *providerB) {
        auto commonSize = std::min(providerA->getActualSize(), providerB->getActualSize());
        m_diffTask = TaskManager::createTask("Diffing...", commonSize, [this, providerA, providerB](Task &) {
            auto differences = m_algorithm->analyze(providerA, providerB);

            // Move the calculated differences over so they can be displayed
            for (size_t i = 0; i < m_columns.size(); i++) {
                auto &column = m_columns[i];
                column.diffTree = std::move(differences[i]);
            }
            m_analyzed = true;
        });
    }

    std::function<std::optional<color_t>(u64, const u8*, size_t)> ViewDiff::createCompareFunction(size_t otherIndex) const {
        const auto currIndex = otherIndex == 0 ? 1 : 0;
        return [=, this](u64 address, const u8 *, size_t size) -> std::optional<color_t> {
            if (!m_analyzed)
                return std::nullopt;

            const auto matches = m_columns[currIndex].diffTree.overlapping({ address, (address + size) - 1 });
            if (matches.empty())
                return std::nullopt;

            const auto type = matches[0].value;

            if (type == DifferenceType::Mismatch) {
                return ImGuiExt::GetCustomColorU32(ImGuiCustomCol_DiffChanged);
            } else if (type == DifferenceType::Insertion && currIndex == 0) {
                return ImGuiExt::GetCustomColorU32(ImGuiCustomCol_DiffAdded);
            } else if (type == DifferenceType::Deletion && currIndex == 1) {
                return ImGuiExt::GetCustomColorU32(ImGuiCustomCol_DiffRemoved);
            }

            return std::nullopt;
        };
    }

    void ViewDiff::drawContent() {
        auto &[a, b] = m_columns;

        a.hexEditor.enableSyncScrolling(false);
        b.hexEditor.enableSyncScrolling(false);

        if (a.scrollLock > 0) a.scrollLock--;
        if (b.scrollLock > 0) b.scrollLock--;

        // Change the hex editor providers if the user selected a new provider
        {
            const auto &providers = ImHexApi::Provider::getProviders();
            if (a.provider >= 0 && size_t(a.provider) < providers.size())
                a.hexEditor.setProvider(providers[a.provider]);
            else
                a.hexEditor.setProvider(nullptr);

            if (b.provider >= 0 && size_t(b.provider) < providers.size())
                b.hexEditor.setProvider(providers[b.provider]);
            else
                b.hexEditor.setProvider(nullptr);
        }

        // Analyze the providers if they are valid and the user selected a new provider
        if (!m_analyzed && a.provider != -1 && b.provider != -1 && !m_diffTask.isRunning() && m_algorithm != nullptr) {
            const auto &providers = ImHexApi::Provider::getProviders();
            auto providerA = providers[a.provider];
            auto providerB = providers[b.provider];

            this->analyze(providerA, providerB);
        }

        if (auto &algorithms = ContentRegistry::Diffing::impl::getAlgorithms(); m_algorithm == nullptr && !algorithms.empty())
            m_algorithm = algorithms.front().get();

        const auto height = ImGui::GetContentRegionAvail().y;

        // Draw the two hex editor columns side by side
        if (ImGui::BeginTable("##binary_diff", 2, ImGuiTableFlags_None, ImVec2(0, height - 250_scaled))) {
            ImGui::TableSetupColumn("hex.diffing.view.diff.provider_a"_lang);
            ImGui::TableSetupColumn("hex.diffing.view.diff.provider_b"_lang);
            ImGui::TableHeadersRow();

            ImVec2 buttonPos;
            ImGui::BeginDisabled(m_diffTask.isRunning());
            {
                // Draw settings button
                ImGui::TableNextColumn();
                if (ImGuiExt::DimmedIconButton(ICON_VS_SETTINGS_GEAR, ImGui::GetStyleColorVec4(ImGuiCol_Text)))
                    ImGui::OpenPopup("DiffingAlgorithmSettings");
                buttonPos = ImGui::GetCursorScreenPos();

                ImGui::SameLine();

                // Draw first provider selector
                if (drawProviderSelector(a)) m_analyzed = false;

                // Draw second provider selector
                ImGui::TableNextColumn();
                if (drawProviderSelector(b)) m_analyzed = false;
            }
            ImGui::EndDisabled();

            ImGui::SetNextWindowPos(buttonPos);
            if (ImGui::BeginPopup("DiffingAlgorithmSettings")) {
                ImGuiExt::Header("hex.diffing.view.diff.algorithm"_lang, true);
                ImGui::PushItemWidth(300_scaled);
                if (ImGui::BeginCombo("##Algorithm", m_algorithm == nullptr ? "" : Lang(m_algorithm->getUnlocalizedName()))) {
                    for (const auto &algorithm : ContentRegistry::Diffing::impl::getAlgorithms()) {
                        ImGui::PushID(algorithm.get());
                        if (ImGui::Selectable(Lang(algorithm->getUnlocalizedName()))) {
                            m_algorithm = algorithm.get();
                            m_analyzed  = false;
                        }
                        ImGui::PopID();
                    }
                    ImGui::EndCombo();
                }
                ImGui::PopItemWidth();

                if (m_algorithm != nullptr) {
                    ImGuiExt::TextFormattedWrapped("{}", Lang(m_algorithm->getUnlocalizedDescription()));
                }

                ImGuiExt::Header("hex.diffing.view.diff.settings"_lang);
                if (m_algorithm != nullptr) {
                    auto drawList = ImGui::GetWindowDrawList();
                    auto prevIdx = drawList->_VtxCurrentIdx;
                    m_algorithm->drawSettings();
                    auto currIdx = drawList->_VtxCurrentIdx;

                    if (prevIdx == currIdx)
                        ImGuiExt::TextFormatted("hex.diffing.view.diff.settings.no_settings"_lang);
                }

                ImGui::EndPopup();
            }

            ImGui::TableNextRow();

            // Draw first hex editor column
            ImGui::TableNextColumn();
            bool scrollB = drawDiffColumn(a, height - 250_scaled);

            // Draw second hex editor column
            ImGui::TableNextColumn();
            bool scrollA = drawDiffColumn(b, height - 250_scaled);

            // Sync the scroll positions of the hex editors
            {
                if (scrollA && a.scrollLock == 0) {
                    a.hexEditor.setScrollPosition(b.hexEditor.getScrollPosition());
                    a.hexEditor.forceUpdateScrollPosition();
                }
                if (scrollB && b.scrollLock == 0) {
                    b.hexEditor.setScrollPosition(a.hexEditor.getScrollPosition());
                    b.hexEditor.forceUpdateScrollPosition();
                }
            }

            ImGui::EndTable();
        }

        // Draw the differences table
        if (ImGui::BeginTable("##differences", 3, ImGuiTableFlags_Borders | ImGuiTableFlags_ScrollY | ImGuiTableFlags_Reorderable | ImGuiTableFlags_Resizable, ImVec2(0, 200_scaled))) {
            ImGui::TableSetupScrollFreeze(0, 1);
            ImGui::TableSetupColumn("hex.ui.common.begin"_lang);
            ImGui::TableSetupColumn("hex.ui.common.end"_lang);
            ImGui::TableSetupColumn("hex.ui.common.type"_lang);
            ImGui::TableHeadersRow();

            // Draw the differences if the providers have been analyzed
            if (m_analyzed) {
                ImGuiListClipper clipper;

                auto &diffTreeA = m_columns[0].diffTree;
                auto &diffTreeB = m_columns[1].diffTree;
                clipper.Begin(int(diffTreeA.size()));

                auto diffIterA = diffTreeA.begin();
                auto diffIterB = diffTreeB.begin();
                while (clipper.Step()) {
                    for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++) {
                        ImGui::TableNextRow();

                        // Prevent the list from trying to access non-existing diffs
                        if (size_t(i) >= diffTreeA.size())
                            break;

                        ImGui::PushID(i);

                        const auto &[startA, restA] = *diffIterA;
                        const auto &[endA, typeA] = restA;

                        const auto &[startB, restB] = *diffIterB;
                        const auto &[endB, typeB] = restB;

                        std::advance(diffIterA, 1);
                        std::advance(diffIterB, 1);

                        // Draw a clickable row for each difference that will select the difference in both hex editors

                        // Draw start address
                        ImGui::TableNextColumn();
                        if (ImGui::Selectable(hex::format("0x{:02X}", startA).c_str(), false, ImGuiSelectableFlags_SpanAllColumns)) {
                            a.hexEditor.setSelection({ startA, ((endA - startA) + 1) });
                            a.hexEditor.jumpToSelection();
                            b.hexEditor.setSelection({ startB, ((endB - startB) + 1) });
                            b.hexEditor.jumpToSelection();
                        }

                        // Draw end address
                        ImGui::TableNextColumn();
                        ImGui::TextUnformatted(hex::format("0x{:02X}", endA).c_str());

                        // Draw difference type
                        ImGui::TableNextColumn();
                        switch (typeA) {
                            case DifferenceType::Mismatch:
                                ImGuiExt::TextFormattedColored(ImGuiExt::GetCustomColorVec4(ImGuiCustomCol_DiffChanged), "hex.diffing.view.diff.modified"_lang);
                                break;
                            case DifferenceType::Insertion:
                                ImGuiExt::TextFormattedColored(ImGuiExt::GetCustomColorVec4(ImGuiCustomCol_DiffAdded), "hex.diffing.view.diff.added"_lang);
                                break;
                            case DifferenceType::Deletion:
                                ImGuiExt::TextFormattedColored(ImGuiExt::GetCustomColorVec4(ImGuiCustomCol_DiffRemoved), "hex.diffing.view.diff.removed"_lang);
                                break;
                            default:
                                break;
                        }

                        ImGui::PopID();
                    }
                }
            }

            ImGui::EndTable();
        }
    }

}