#include <XCEditor/Workspace/UIEditorWindowWorkspaceController.h>

#include <XCEditor/Workspace/UIEditorWorkspaceTransfer.h>

#include <algorithm>
#include <utility>

namespace XCEngine::UI::Editor {

namespace {

bool IsSinglePanelRootWindow(
    const UIEditorWindowWorkspaceState& state,
    std::string_view panelId) {
    const UIEditorWorkspaceNode& root = state.workspace.root;
    return root.kind == UIEditorWorkspaceNodeKind::TabStack &&
        root.children.size() == 1u &&
        root.children.front().kind == UIEditorWorkspaceNodeKind::Panel &&
        root.children.front().panel.panelId == panelId &&
        state.session.panelStates.size() == 1u &&
        state.session.panelStates.front().panelId == panelId;
}

bool TryExtractPanelFromWindow(
    UIEditorWindowWorkspaceSet& windowSet,
    std::string_view sourceWindowId,
    std::string_view primaryWindowId,
    std::string_view sourceNodeId,
    std::string_view panelId,
    UIEditorWorkspaceExtractedPanel& extractedPanel) {
    UIEditorWindowWorkspaceState* sourceWindow =
        FindMutableUIEditorWindowWorkspaceState(windowSet, sourceWindowId);
    if (sourceWindow == nullptr) {
        return false;
    }

    if (sourceWindowId != primaryWindowId &&
        IsSinglePanelRootWindow(*sourceWindow, panelId)) {
        extractedPanel.panelNode = std::move(sourceWindow->workspace.root.children.front());
        extractedPanel.sessionState = sourceWindow->session.panelStates.front();
        windowSet.windows.erase(
            std::remove_if(
                windowSet.windows.begin(),
                windowSet.windows.end(),
                [sourceWindowId](const UIEditorWindowWorkspaceState& state) {
                    return state.windowId == sourceWindowId;
                }),
            windowSet.windows.end());
        return true;
    }

    return TryExtractUIEditorWorkspaceVisiblePanel(
        sourceWindow->workspace,
        sourceWindow->session,
        sourceNodeId,
        panelId,
        extractedPanel);
}

} // namespace

std::string_view GetUIEditorWindowWorkspaceOperationStatusName(
    UIEditorWindowWorkspaceOperationStatus status) {
    switch (status) {
    case UIEditorWindowWorkspaceOperationStatus::Changed:
        return "Changed";
    case UIEditorWindowWorkspaceOperationStatus::NoOp:
        return "NoOp";
    case UIEditorWindowWorkspaceOperationStatus::Rejected:
        return "Rejected";
    }

    return "Unknown";
}

UIEditorWindowWorkspaceController::UIEditorWindowWorkspaceController(
    UIEditorPanelRegistry panelRegistry,
    UIEditorWindowWorkspaceSet windowSet)
    : m_panelRegistry(std::move(panelRegistry))
    , m_windowSet(std::move(windowSet)) {
}

UIEditorWindowWorkspaceValidationResult UIEditorWindowWorkspaceController::ValidateState() const {
    return ValidateUIEditorWindowWorkspaceSet(m_panelRegistry, m_windowSet);
}

UIEditorWindowWorkspaceOperationResult UIEditorWindowWorkspaceController::BuildOperationResult(
    UIEditorWindowWorkspaceOperationStatus status,
    std::string message,
    std::string_view sourceWindowId,
    std::string_view targetWindowId,
    std::string_view panelId) const {
    UIEditorWindowWorkspaceOperationResult result = {};
    result.status = status;
    result.message = std::move(message);
    result.sourceWindowId = std::string(sourceWindowId);
    result.targetWindowId = std::string(targetWindowId);
    result.panelId = std::string(panelId);
    result.activeWindowId = m_windowSet.activeWindowId;
    result.windowIds.reserve(m_windowSet.windows.size());
    for (const UIEditorWindowWorkspaceState& state : m_windowSet.windows) {
        result.windowIds.push_back(state.windowId);
    }
    return result;
}

std::string UIEditorWindowWorkspaceController::MakeUniqueWindowId(std::string_view base) const {
    std::string resolvedBase = base.empty()
        ? std::string("detached-window")
        : std::string(base);
    if (FindUIEditorWindowWorkspaceState(m_windowSet, resolvedBase) == nullptr) {
        return resolvedBase;
    }

    for (std::size_t suffix = 1u; suffix < 1024u; ++suffix) {
        const std::string candidate = resolvedBase + "-" + std::to_string(suffix);
        if (FindUIEditorWindowWorkspaceState(m_windowSet, candidate) == nullptr) {
            return candidate;
        }
    }

    return resolvedBase + "-overflow";
}

UIEditorWindowWorkspaceOperationResult UIEditorWindowWorkspaceController::DetachPanelToNewWindow(
    std::string_view sourceWindowId,
    std::string_view sourceNodeId,
    std::string_view panelId,
    std::string_view preferredNewWindowId) {
    const UIEditorWindowWorkspaceValidationResult stateValidation = ValidateState();
    if (!stateValidation.IsValid()) {
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Window workspace state invalid: " + stateValidation.message,
            sourceWindowId,
            {},
            panelId);
    }

    const UIEditorWindowWorkspaceState* sourceWindow =
        FindUIEditorWindowWorkspaceState(m_windowSet, sourceWindowId);
    if (sourceWindow == nullptr) {
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Source window not found.",
            sourceWindowId,
            {},
            panelId);
    }

    if (sourceWindowId != m_windowSet.primaryWindowId &&
        IsSinglePanelRootWindow(*sourceWindow, panelId)) {
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::NoOp,
            "Panel already occupies its own detached window.",
            sourceWindowId,
            sourceWindowId,
            panelId);
    }

    const UIEditorWindowWorkspaceSet windowSetBefore = m_windowSet;
    UIEditorWorkspaceExtractedPanel extractedPanel = {};
    if (!TryExtractPanelFromWindow(
            m_windowSet,
            sourceWindowId,
            m_windowSet.primaryWindowId,
            sourceNodeId,
            panelId,
            extractedPanel)) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Failed to extract panel from source window.",
            sourceWindowId,
            {},
            panelId);
    }

    const std::string newWindowId = MakeUniqueWindowId(
        preferredNewWindowId.empty()
            ? std::string(panelId) + "-window"
            : std::string(preferredNewWindowId));
    UIEditorWindowWorkspaceState detachedWindow = {};
    detachedWindow.windowId = newWindowId;
    detachedWindow.workspace =
        BuildUIEditorDetachedWorkspaceFromExtractedPanel(
            newWindowId + "-root",
            extractedPanel);
    detachedWindow.session =
        BuildUIEditorDetachedWorkspaceSessionFromExtractedPanel(extractedPanel);
    m_windowSet.windows.push_back(std::move(detachedWindow));
    m_windowSet.activeWindowId = newWindowId;

    const UIEditorWindowWorkspaceValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Detach produced invalid state: " + validation.message,
            sourceWindowId,
            newWindowId,
            panelId);
    }

    return BuildOperationResult(
        UIEditorWindowWorkspaceOperationStatus::Changed,
        "Panel detached into a new window.",
        sourceWindowId,
        newWindowId,
        panelId);
}

UIEditorWindowWorkspaceOperationResult UIEditorWindowWorkspaceController::MovePanelToStack(
    std::string_view sourceWindowId,
    std::string_view sourceNodeId,
    std::string_view panelId,
    std::string_view targetWindowId,
    std::string_view targetNodeId,
    std::size_t targetVisibleInsertionIndex) {
    const UIEditorWindowWorkspaceValidationResult stateValidation = ValidateState();
    if (!stateValidation.IsValid()) {
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Window workspace state invalid: " + stateValidation.message,
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    if (sourceWindowId == targetWindowId) {
        UIEditorWindowWorkspaceState* window =
            FindMutableUIEditorWindowWorkspaceState(m_windowSet, sourceWindowId);
        if (window == nullptr) {
            return BuildOperationResult(
                UIEditorWindowWorkspaceOperationStatus::Rejected,
                "Source window not found.",
                sourceWindowId,
                targetWindowId,
                panelId);
        }

        if (!TryMoveUIEditorWorkspaceTabToStack(
                window->workspace,
                window->session,
                sourceNodeId,
                panelId,
                targetNodeId,
                targetVisibleInsertionIndex)) {
            return BuildOperationResult(
                UIEditorWindowWorkspaceOperationStatus::Rejected,
                "Move operation rejected by the workspace model.",
                sourceWindowId,
                targetWindowId,
                panelId);
        }

        m_windowSet.activeWindowId = std::string(targetWindowId);
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Changed,
            "Panel moved within the same window.",
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    const UIEditorWindowWorkspaceSet windowSetBefore = m_windowSet;
    UIEditorWorkspaceExtractedPanel extractedPanel = {};
    if (!TryExtractPanelFromWindow(
            m_windowSet,
            sourceWindowId,
            m_windowSet.primaryWindowId,
            sourceNodeId,
            panelId,
            extractedPanel)) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Failed to extract panel from source window.",
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    UIEditorWindowWorkspaceState* targetWindow =
        FindMutableUIEditorWindowWorkspaceState(m_windowSet, targetWindowId);
    if (targetWindow == nullptr ||
        !TryInsertExtractedUIEditorWorkspacePanelToStack(
            targetWindow->workspace,
            targetWindow->session,
            std::move(extractedPanel),
            targetNodeId,
            targetVisibleInsertionIndex)) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Failed to insert the extracted panel into the target stack.",
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    m_windowSet.activeWindowId = std::string(targetWindowId);
    const UIEditorWindowWorkspaceValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Move produced invalid state: " + validation.message,
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    return BuildOperationResult(
        UIEditorWindowWorkspaceOperationStatus::Changed,
        "Panel moved across windows.",
        sourceWindowId,
        targetWindowId,
        panelId);
}

UIEditorWindowWorkspaceOperationResult UIEditorWindowWorkspaceController::DockPanelRelative(
    std::string_view sourceWindowId,
    std::string_view sourceNodeId,
    std::string_view panelId,
    std::string_view targetWindowId,
    std::string_view targetNodeId,
    UIEditorWorkspaceDockPlacement placement,
    float splitRatio) {
    const UIEditorWindowWorkspaceValidationResult stateValidation = ValidateState();
    if (!stateValidation.IsValid()) {
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Window workspace state invalid: " + stateValidation.message,
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    if (sourceWindowId == targetWindowId) {
        UIEditorWindowWorkspaceState* window =
            FindMutableUIEditorWindowWorkspaceState(m_windowSet, sourceWindowId);
        if (window == nullptr) {
            return BuildOperationResult(
                UIEditorWindowWorkspaceOperationStatus::Rejected,
                "Source window not found.",
                sourceWindowId,
                targetWindowId,
                panelId);
        }

        if (!TryDockUIEditorWorkspaceTabRelative(
                window->workspace,
                window->session,
                sourceNodeId,
                panelId,
                targetNodeId,
                placement,
                splitRatio)) {
            return BuildOperationResult(
                UIEditorWindowWorkspaceOperationStatus::Rejected,
                "Dock operation rejected by the workspace model.",
                sourceWindowId,
                targetWindowId,
                panelId);
        }

        m_windowSet.activeWindowId = std::string(targetWindowId);
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Changed,
            "Panel docked within the same window.",
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    const UIEditorWindowWorkspaceSet windowSetBefore = m_windowSet;
    UIEditorWorkspaceExtractedPanel extractedPanel = {};
    if (!TryExtractPanelFromWindow(
            m_windowSet,
            sourceWindowId,
            m_windowSet.primaryWindowId,
            sourceNodeId,
            panelId,
            extractedPanel)) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Failed to extract panel from source window.",
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    UIEditorWindowWorkspaceState* targetWindow =
        FindMutableUIEditorWindowWorkspaceState(m_windowSet, targetWindowId);
    if (targetWindow == nullptr ||
        !TryDockExtractedUIEditorWorkspacePanelRelative(
            targetWindow->workspace,
            targetWindow->session,
            std::move(extractedPanel),
            targetNodeId,
            placement,
            splitRatio)) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Failed to dock the extracted panel into the target window.",
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    m_windowSet.activeWindowId = std::string(targetWindowId);
    const UIEditorWindowWorkspaceValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        m_windowSet = windowSetBefore;
        return BuildOperationResult(
            UIEditorWindowWorkspaceOperationStatus::Rejected,
            "Dock produced invalid state: " + validation.message,
            sourceWindowId,
            targetWindowId,
            panelId);
    }

    return BuildOperationResult(
        UIEditorWindowWorkspaceOperationStatus::Changed,
        "Panel docked across windows.",
        sourceWindowId,
        targetWindowId,
        panelId);
}

UIEditorWindowWorkspaceController BuildDefaultUIEditorWindowWorkspaceController(
    const UIEditorPanelRegistry& panelRegistry,
    const UIEditorWorkspaceModel& workspace,
    std::string primaryWindowId) {
    return UIEditorWindowWorkspaceController(
        panelRegistry,
        BuildDefaultUIEditorWindowWorkspaceSet(
            panelRegistry,
            workspace,
            std::move(primaryWindowId)));
}

} // namespace XCEngine::UI::Editor