#include "Project/ProductProjectBrowserModel.h"

#include <algorithm>
#include <cctype>
#include <string_view>
#include <system_error>

#include <windows.h>

namespace XCEngine::UI::Editor::App::Project {

namespace {

constexpr std::string_view kAssetsRootId = "Assets";

std::string ToLowerCopy(std::string value) {
    std::transform(
        value.begin(),
        value.end(),
        value.begin(),
        [](unsigned char character) {
            return static_cast<char>(std::tolower(character));
        });
    return value;
}

std::string WideToUtf8(std::wstring_view value) {
    if (value.empty()) {
        return {};
    }

    const int requiredSize = WideCharToMultiByte(
        CP_UTF8,
        0,
        value.data(),
        static_cast<int>(value.size()),
        nullptr,
        0,
        nullptr,
        nullptr);
    if (requiredSize <= 0) {
        return {};
    }

    std::string result(static_cast<std::size_t>(requiredSize), '\0');
    WideCharToMultiByte(
        CP_UTF8,
        0,
        value.data(),
        static_cast<int>(value.size()),
        result.data(),
        requiredSize,
        nullptr,
        nullptr);
    return result;
}

std::string PathToUtf8String(const std::filesystem::path& path) {
    return WideToUtf8(path.native());
}

std::string NormalizePathSeparators(std::string value) {
    std::replace(value.begin(), value.end(), '\\', '/');
    return value;
}

std::string BuildRelativeItemId(
    const std::filesystem::path& path,
    const std::filesystem::path& assetsRoot) {
    const std::filesystem::path relative =
        std::filesystem::relative(path, assetsRoot.parent_path());
    const std::string normalized =
        NormalizePathSeparators(PathToUtf8String(relative.lexically_normal()));
    return normalized.empty() ? std::string(kAssetsRootId) : normalized;
}

std::string BuildAssetDisplayName(const std::filesystem::path& path, bool directory) {
    if (directory) {
        return PathToUtf8String(path.filename());
    }

    const std::string filename = PathToUtf8String(path.filename());
    const std::size_t extensionOffset = filename.find_last_of('.');
    if (extensionOffset == std::string::npos || extensionOffset == 0u) {
        return filename;
    }

    return filename.substr(0u, extensionOffset);
}

bool IsMetaFile(const std::filesystem::path& path) {
    return ToLowerCopy(path.extension().string()) == ".meta";
}

bool HasChildDirectories(const std::filesystem::path& folderPath) {
    std::error_code errorCode = {};
    const std::filesystem::directory_iterator end = {};
    for (std::filesystem::directory_iterator iterator(folderPath, errorCode);
         !errorCode && iterator != end;
         iterator.increment(errorCode)) {
        if (iterator->is_directory(errorCode)) {
            return true;
        }
    }

    return false;
}

std::vector<std::filesystem::path> CollectSortedChildDirectories(
    const std::filesystem::path& folderPath) {
    std::vector<std::filesystem::path> paths = {};
    std::error_code errorCode = {};
    const std::filesystem::directory_iterator end = {};
    for (std::filesystem::directory_iterator iterator(folderPath, errorCode);
         !errorCode && iterator != end;
         iterator.increment(errorCode)) {
        if (iterator->is_directory(errorCode)) {
            paths.push_back(iterator->path());
        }
    }

    std::sort(
        paths.begin(),
        paths.end(),
        [](const std::filesystem::path& lhs, const std::filesystem::path& rhs) {
            return ToLowerCopy(PathToUtf8String(lhs.filename())) <
                ToLowerCopy(PathToUtf8String(rhs.filename()));
        });
    return paths;
}

} // namespace

void ProductProjectBrowserModel::Initialize(const std::filesystem::path& repoRoot) {
    m_assetsRootPath = (repoRoot / "project/Assets").lexically_normal();
    Refresh();
}

void ProductProjectBrowserModel::SetFolderIcon(const ::XCEngine::UI::UITextureHandle& icon) {
    m_folderIcon = icon;
    if (!m_assetsRootPath.empty()) {
        RefreshFolderTree();
    }
}

void ProductProjectBrowserModel::Refresh() {
    RefreshFolderTree();
    EnsureValidCurrentFolder();
    RefreshAssetList();
}

bool ProductProjectBrowserModel::Empty() const {
    return m_treeItems.empty();
}

const std::filesystem::path& ProductProjectBrowserModel::GetAssetsRootPath() const {
    return m_assetsRootPath;
}

const std::vector<ProductProjectBrowserModel::FolderEntry>& ProductProjectBrowserModel::GetFolderEntries() const {
    return m_folderEntries;
}

const std::vector<Widgets::UIEditorTreeViewItem>& ProductProjectBrowserModel::GetTreeItems() const {
    return m_treeItems;
}

const std::vector<ProductProjectBrowserModel::AssetEntry>& ProductProjectBrowserModel::GetAssetEntries() const {
    return m_assetEntries;
}

const std::string& ProductProjectBrowserModel::GetCurrentFolderId() const {
    return m_currentFolderId;
}

const ProductProjectBrowserModel::FolderEntry* ProductProjectBrowserModel::FindFolderEntry(
    std::string_view itemId) const {
    for (const FolderEntry& entry : m_folderEntries) {
        if (entry.itemId == itemId) {
            return &entry;
        }
    }

    return nullptr;
}

const ProductProjectBrowserModel::AssetEntry* ProductProjectBrowserModel::FindAssetEntry(
    std::string_view itemId) const {
    for (const AssetEntry& entry : m_assetEntries) {
        if (entry.itemId == itemId) {
            return &entry;
        }
    }

    return nullptr;
}

bool ProductProjectBrowserModel::NavigateToFolder(std::string_view itemId) {
    if (itemId.empty() || FindFolderEntry(itemId) == nullptr || itemId == m_currentFolderId) {
        return false;
    }

    m_currentFolderId = std::string(itemId);
    EnsureValidCurrentFolder();
    RefreshAssetList();
    return true;
}

std::vector<ProductProjectBrowserModel::BreadcrumbSegment> ProductProjectBrowserModel::BuildBreadcrumbSegments() const {
    std::vector<BreadcrumbSegment> segments = {};
    if (m_currentFolderId.empty()) {
        segments.push_back(BreadcrumbSegment{ std::string(kAssetsRootId), std::string(kAssetsRootId), true });
        return segments;
    }

    std::string cumulativeFolderId = {};
    std::size_t segmentStart = 0u;
    while (segmentStart < m_currentFolderId.size()) {
        const std::size_t separator = m_currentFolderId.find('/', segmentStart);
        const std::size_t segmentLength =
            separator == std::string_view::npos
                ? m_currentFolderId.size() - segmentStart
                : separator - segmentStart;
        if (segmentLength > 0u) {
            std::string label = std::string(m_currentFolderId.substr(segmentStart, segmentLength));
            if (cumulativeFolderId.empty()) {
                cumulativeFolderId = label;
            } else {
                cumulativeFolderId += "/";
                cumulativeFolderId += label;
            }

            segments.push_back(BreadcrumbSegment{
                std::move(label),
                cumulativeFolderId,
                false
            });
        }
        if (separator == std::string_view::npos) {
            break;
        }
        segmentStart = separator + 1u;
    }

    if (segments.empty()) {
        segments.push_back(BreadcrumbSegment{ std::string(kAssetsRootId), std::string(kAssetsRootId), true });
        return segments;
    }

    segments.back().current = true;
    return segments;
}

std::vector<std::string> ProductProjectBrowserModel::CollectCurrentFolderAncestorIds() const {
    return BuildAncestorFolderIds(m_currentFolderId);
}

std::vector<std::string> ProductProjectBrowserModel::BuildAncestorFolderIds(
    std::string_view itemId) const {
    std::vector<std::string> ancestors = {};
    const FolderEntry* folderEntry = FindFolderEntry(itemId);
    if (folderEntry == nullptr) {
        return ancestors;
    }

    std::filesystem::path path = folderEntry->absolutePath;
    while (true) {
        ancestors.push_back(BuildRelativeItemId(path, m_assetsRootPath));
        if (path == m_assetsRootPath) {
            break;
        }
        path = path.parent_path();
    }

    std::reverse(ancestors.begin(), ancestors.end());
    return ancestors;
}

void ProductProjectBrowserModel::RefreshFolderTree() {
    m_folderEntries.clear();
    m_treeItems.clear();

    if (m_assetsRootPath.empty() || !std::filesystem::exists(m_assetsRootPath)) {
        return;
    }

    const auto appendFolderRecursive =
        [&](auto&& self, const std::filesystem::path& folderPath, std::uint32_t depth) -> void {
        const std::string itemId = BuildRelativeItemId(folderPath, m_assetsRootPath);

        FolderEntry folderEntry = {};
        folderEntry.itemId = itemId;
        folderEntry.absolutePath = folderPath;
        folderEntry.label = PathToUtf8String(folderPath.filename());
        m_folderEntries.push_back(folderEntry);

        Widgets::UIEditorTreeViewItem item = {};
        item.itemId = itemId;
        item.label = folderEntry.label;
        item.depth = depth;
        item.forceLeaf = !HasChildDirectories(folderPath);
        item.leadingIcon = m_folderIcon;
        m_treeItems.push_back(std::move(item));

        const std::vector<std::filesystem::path> childFolders =
            CollectSortedChildDirectories(folderPath);
        for (const std::filesystem::path& childPath : childFolders) {
            self(self, childPath, depth + 1u);
        }
    };

    appendFolderRecursive(appendFolderRecursive, m_assetsRootPath, 0u);
}

void ProductProjectBrowserModel::RefreshAssetList() {
    EnsureValidCurrentFolder();

    m_assetEntries.clear();
    const FolderEntry* currentFolder = FindFolderEntry(m_currentFolderId);
    if (currentFolder == nullptr) {
        return;
    }

    std::vector<std::filesystem::directory_entry> entries = {};
    std::error_code errorCode = {};
    const std::filesystem::directory_iterator end = {};
    for (std::filesystem::directory_iterator iterator(currentFolder->absolutePath, errorCode);
         !errorCode && iterator != end;
         iterator.increment(errorCode)) {
        if (!iterator->exists(errorCode) || IsMetaFile(iterator->path())) {
            continue;
        }
        if (!iterator->is_directory(errorCode) && !iterator->is_regular_file(errorCode)) {
            continue;
        }

        entries.push_back(*iterator);
    }

    std::sort(
        entries.begin(),
        entries.end(),
        [](const std::filesystem::directory_entry& lhs, const std::filesystem::directory_entry& rhs) {
            const bool lhsDirectory = lhs.is_directory();
            const bool rhsDirectory = rhs.is_directory();
            if (lhsDirectory != rhsDirectory) {
                return lhsDirectory && !rhsDirectory;
            }

            return ToLowerCopy(PathToUtf8String(lhs.path().filename())) <
                ToLowerCopy(PathToUtf8String(rhs.path().filename()));
        });

    for (const std::filesystem::directory_entry& entry : entries) {
        AssetEntry assetEntry = {};
        assetEntry.itemId = BuildRelativeItemId(entry.path(), m_assetsRootPath);
        assetEntry.absolutePath = entry.path();
        assetEntry.displayName = BuildAssetDisplayName(entry.path(), entry.is_directory());
        assetEntry.directory = entry.is_directory();
        m_assetEntries.push_back(std::move(assetEntry));
    }
}

void ProductProjectBrowserModel::EnsureValidCurrentFolder() {
    if (m_currentFolderId.empty()) {
        m_currentFolderId = std::string(kAssetsRootId);
    }

    if (FindFolderEntry(m_currentFolderId) == nullptr) {
        m_currentFolderId = m_treeItems.empty()
            ? std::string()
            : m_treeItems.front().itemId;
    }
}

} // namespace XCEngine::UI::Editor::App::Project