#include <destrum/Util/AssetBrowser.h>

#include <algorithm>
#include <array>
#include <cctype>

#include <imgui.h>

#include <destrum/FS/AssetFS.h>
#include <destrum/Util/ImGuiUtils.h>

namespace {
    [[nodiscard]] std::string Lowercase(std::string_view value) {
        std::string result{value};
        std::ranges::transform(result, result.begin(), [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
        return result;
    }

    [[nodiscard]] bool HasExtension(std::string_view path, std::initializer_list<std::string_view> extensions) {
        const std::string extension = Lowercase(std::filesystem::path{path}.extension().string());
        return std::ranges::find(extensions, extension) != extensions.end();
    }

    // Cooker outputs and bookkeeping sit next to the sources in the runtime folders, nobody picks those
    [[nodiscard]] bool IsHidden(const std::filesystem::path& path) {
        return path.filename() == "manifest.json" || HasExtension(path.string(), {".dmodel", ".dtex", ".spv"});
    }

    [[nodiscard]] const FSMount* FindMount(const std::string& scheme) {
        for (const FSMount& mount : AssetFS::GetInstance().GetMounts()) {
            if (mount.scheme == scheme) {
                return &mount;
            }
        }
        return nullptr;
    }
}

bool AssetBrowser::IsModel(std::string_view path) {
    return HasExtension(path, {".fbx", ".glb", ".gltf", ".obj"});
}

void AssetBrowser::Draw(bool* open) {
    if (!ImGui::Begin("Assets", open)) {
        ImGui::End();
        return;
    }

    const auto& mounts = AssetFS::GetInstance().GetMounts();
    if (mounts.empty()) {
        ImGui::TextDisabled("No asset folders are mounted");
        ImGui::End();
        return;
    }
    if (FindMount(m_Scheme) == nullptr) {
        Navigate(mounts.front().scheme, {});
    }

    for (const FSMount& mount : mounts) {
        if (ImGui::RadioButton(mount.scheme.c_str(), m_Scheme == mount.scheme)) {
            Navigate(mount.scheme, {});
        }
        ImGui::SameLine();
    }
    if (ImGui::Button("Refresh")) {
        m_Dirty = true;
    }
    ImGui::SameLine();
    ImGui::SetNextItemWidth(-FLT_MIN);
    ImGuiUtils::InputString("##Filter", m_Filter, 0, "Search this folder");

    ImGui::BeginDisabled(m_Folder.empty());
    if (ImGui::ArrowButton("##Up", ImGuiDir_Up)) {
        Navigate(m_Scheme, m_Folder.parent_path());
    }
    ImGui::EndDisabled();
    ImGui::SameLine();
    ImGui::TextUnformatted((m_Scheme + "://" + m_Folder.generic_string()).c_str());
    ImGui::Separator();

    if (m_Dirty) {
        Refresh();
    }

    if (ImGui::BeginChild("Entries")) {
        const std::string filter = Lowercase(m_Filter);
        for (const Entry& entry : m_Entries) {
            if ((filter.empty() || Lowercase(entry.name).find(filter) != std::string::npos) && DrawEntry(entry)) {
                // Entered a folder, the list is rebuilt next frame
                break;
            }
        }
    }
    ImGui::EndChild();

    ImGui::End();
}

bool AssetBrowser::DrawEntry(const Entry& entry) {
    bool navigated = false;
    const std::string virtualPath = m_Scheme + "://" + (m_Folder / entry.name).generic_string();
    const std::string label = (entry.directory ? "[dir]  " : IsModel(entry.name) ? "[model]  " : "") + entry.name;

    ImGui::PushID(entry.name.c_str());
    if (ImGui::Selectable(label.c_str(), false, ImGuiSelectableFlags_AllowDoubleClick) &&
        entry.directory && ImGui::IsMouseDoubleClicked(ImGuiMouseButton_Left)) {
        Navigate(m_Scheme, m_Folder / entry.name);
        navigated = true;
    }

    if (!entry.directory && ImGui::BeginDragDropSource()) {
        ImGui::SetDragDropPayload(ImGuiUtils::AssetPayload, virtualPath.c_str(), virtualPath.size() + 1);
        ImGui::TextUnformatted(virtualPath.c_str());
        if (IsModel(entry.name)) {
            ImGui::TextDisabled("Drop it in the viewport to place it");
        }
        ImGui::EndDragDropSource();
    }

    if (ImGui::BeginPopupContextItem("EntryMenu")) {
        if (ImGui::MenuItem("Copy Path")) {
            ImGui::SetClipboardText(virtualPath.c_str());
        }
        ImGui::EndPopup();
    }
    ImGui::SetItemTooltip("%s", virtualPath.c_str());
    ImGui::PopID();
    return navigated;
}

void AssetBrowser::Navigate(const std::string& scheme, const std::filesystem::path& folder) {
    m_Scheme = scheme;
    m_Folder = folder;
    m_Filter.clear();
    m_Dirty = true;
}

void AssetBrowser::Refresh() {
    m_Dirty = false;
    m_Entries.clear();

    const FSMount* mount = FindMount(m_Scheme);
    if (mount == nullptr) {
        return;
    }

    std::error_code error;
    for (const auto& item : std::filesystem::directory_iterator(mount->root / m_Folder, error)) {
        if (IsHidden(item.path())) {
            continue;
        }
        m_Entries.push_back({
            .name = item.path().filename().string(),
            .directory = item.is_directory(error),
        });
    }

    std::ranges::sort(m_Entries, [](const Entry& a, const Entry& b) {
        if (a.directory != b.directory) {
            return a.directory;
        }
        return Lowercase(a.name) < Lowercase(b.name);
    });
}