#include <XCEditor/Shell/UIEditorWorkspaceController.h>
#include <XCEditor/Foundation/UIEditorRuntimeTrace.h>

#include <cmath>
#include <sstream>
#include <utility>

namespace XCEngine::UI::Editor {

namespace {

bool IsPanelOpenAndVisible(
    const UIEditorWorkspaceSession& session,
    std::string_view panelId) {
    const UIEditorPanelSessionState* panelState =
        FindUIEditorPanelSessionState(session, panelId);
    return panelState != nullptr && panelState->open && panelState->visible;
}

std::vector<std::string> CollectVisiblePanelIds(
    const UIEditorWorkspaceModel& workspace,
    const UIEditorWorkspaceSession& session) {
    const std::vector<UIEditorWorkspaceVisiblePanel> panels =
        CollectUIEditorWorkspaceVisiblePanels(workspace, session);

    std::vector<std::string> ids = {};
    ids.reserve(panels.size());
    for (const UIEditorWorkspaceVisiblePanel& panel : panels) {
        ids.push_back(panel.panelId);
    }

    return ids;
}

struct VisibleTabStackInfo {
    bool panelExists = false;
    bool panelVisible = false;
    std::size_t currentVisibleIndex = 0u;
    std::size_t visibleTabCount = 0u;
};

VisibleTabStackInfo ResolveVisibleTabStackInfo(
    const UIEditorWorkspaceNode& node,
    const UIEditorWorkspaceSession& session,
    std::string_view panelId) {
    VisibleTabStackInfo info = {};
    for (const UIEditorWorkspaceNode& child : node.children) {
        if (child.kind != UIEditorWorkspaceNodeKind::Panel) {
            continue;
        }

        const bool visible = IsPanelOpenAndVisible(session, child.panel.panelId);
        if (child.panel.panelId == panelId) {
            info.panelExists = true;
            info.panelVisible = visible;
            if (visible) {
                info.currentVisibleIndex = info.visibleTabCount;
            }
        }

        if (visible) {
            ++info.visibleTabCount;
        }
    }

    return info;
}

std::size_t CountVisibleTabs(
    const UIEditorWorkspaceNode& node,
    const UIEditorWorkspaceSession& session) {
    if (node.kind != UIEditorWorkspaceNodeKind::TabStack) {
        return 0u;
    }

    std::size_t visibleCount = 0u;
    for (const UIEditorWorkspaceNode& child : node.children) {
        if (child.kind == UIEditorWorkspaceNodeKind::Panel &&
            IsPanelOpenAndVisible(session, child.panel.panelId)) {
            ++visibleCount;
        }
    }

    return visibleCount;
}

} // namespace

std::string_view GetUIEditorWorkspaceCommandKindName(UIEditorWorkspaceCommandKind kind) {
    switch (kind) {
    case UIEditorWorkspaceCommandKind::OpenPanel:
        return "OpenPanel";
    case UIEditorWorkspaceCommandKind::ClosePanel:
        return "ClosePanel";
    case UIEditorWorkspaceCommandKind::ShowPanel:
        return "ShowPanel";
    case UIEditorWorkspaceCommandKind::HidePanel:
        return "HidePanel";
    case UIEditorWorkspaceCommandKind::ActivatePanel:
        return "ActivatePanel";
    case UIEditorWorkspaceCommandKind::ResetWorkspace:
        return "ResetWorkspace";
    }

    return "Unknown";
}

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

    return "Unknown";
}

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

    return "Unknown";
}

UIEditorWorkspaceController::UIEditorWorkspaceController(
    UIEditorPanelRegistry panelRegistry,
    UIEditorWorkspaceModel workspace,
    UIEditorWorkspaceSession session)
    : m_panelRegistry(std::move(panelRegistry))
    , m_baselineWorkspace(CanonicalizeUIEditorWorkspaceModel(workspace))
    , m_baselineSession(session)
    , m_workspace(m_baselineWorkspace)
    , m_session(std::move(session)) {
}

UIEditorWorkspaceControllerValidationResult UIEditorWorkspaceController::ValidateState() const {
    const UIEditorPanelRegistryValidationResult registryValidation =
        ValidateUIEditorPanelRegistry(m_panelRegistry);
    if (!registryValidation.IsValid()) {
        UIEditorWorkspaceControllerValidationResult result = {};
        result.code = UIEditorWorkspaceControllerValidationCode::InvalidPanelRegistry;
        result.message = registryValidation.message;
        return result;
    }

    const UIEditorWorkspaceValidationResult workspaceValidation =
        ValidateUIEditorWorkspace(m_workspace);
    if (!workspaceValidation.IsValid()) {
        UIEditorWorkspaceControllerValidationResult result = {};
        result.code = UIEditorWorkspaceControllerValidationCode::InvalidWorkspace;
        result.message = workspaceValidation.message;
        return result;
    }

    const UIEditorWorkspaceSessionValidationResult sessionValidation =
        ValidateUIEditorWorkspaceSession(m_panelRegistry, m_workspace, m_session);
    if (!sessionValidation.IsValid()) {
        UIEditorWorkspaceControllerValidationResult result = {};
        result.code = UIEditorWorkspaceControllerValidationCode::InvalidWorkspaceSession;
        result.message = sessionValidation.message;
        return result;
    }

    return {};
}

UIEditorWorkspaceLayoutSnapshot UIEditorWorkspaceController::CaptureLayoutSnapshot() const {
    return BuildUIEditorWorkspaceLayoutSnapshot(m_workspace, m_session);
}

UIEditorWorkspaceCommandResult UIEditorWorkspaceController::BuildResult(
    const UIEditorWorkspaceCommand& command,
    UIEditorWorkspaceCommandStatus status,
    std::string message) const {
    UIEditorWorkspaceCommandResult result = {};
    result.kind = command.kind;
    result.status = status;
    result.panelId = command.panelId;
    result.message = std::move(message);
    result.activePanelId = m_workspace.activePanelId;
    result.visiblePanelIds = CollectVisiblePanelIds(m_workspace, m_session);
    return result;
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::BuildLayoutOperationResult(
    UIEditorWorkspaceLayoutOperationStatus status,
    std::string message) const {
    UIEditorWorkspaceLayoutOperationResult result = {};
    result.status = status;
    result.message = std::move(message);
    result.activePanelId = m_workspace.activePanelId;
    result.visiblePanelIds = CollectVisiblePanelIds(m_workspace, m_session);
    return result;
}

UIEditorWorkspaceCommandResult UIEditorWorkspaceController::FinalizeMutation(
    const UIEditorWorkspaceCommand& command,
    bool changed,
    std::string changedMessage,
    std::string unexpectedFailureMessage,
    const UIEditorWorkspaceModel& previousWorkspace,
    const UIEditorWorkspaceSession& previousSession) {
    if (!changed) {
        return BuildResult(
            command,
            UIEditorWorkspaceCommandStatus::Rejected,
            std::move(unexpectedFailureMessage));
    }

    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        m_workspace = previousWorkspace;
        m_session = previousSession;
        return BuildResult(
            command,
            UIEditorWorkspaceCommandStatus::Rejected,
            "Command produced invalid workspace state: " + validation.message);
    }

    return BuildResult(
        command,
        UIEditorWorkspaceCommandStatus::Changed,
        std::move(changedMessage));
}

const UIEditorPanelDescriptor* UIEditorWorkspaceController::FindPanelDescriptor(
    std::string_view panelId) const {
    return FindUIEditorPanelDescriptor(m_panelRegistry, panelId);
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::RestoreLayoutSnapshot(
    const UIEditorWorkspaceLayoutSnapshot& snapshot) {
    UIEditorWorkspaceLayoutSnapshot canonicalSnapshot = snapshot;
    canonicalSnapshot.workspace =
        CanonicalizeUIEditorWorkspaceModel(std::move(canonicalSnapshot.workspace));

    const UIEditorPanelRegistryValidationResult registryValidation =
        ValidateUIEditorPanelRegistry(m_panelRegistry);
    if (!registryValidation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Panel registry invalid: " + registryValidation.message);
    }

    const UIEditorWorkspaceValidationResult workspaceValidation =
        ValidateUIEditorWorkspace(canonicalSnapshot.workspace);
    if (!workspaceValidation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Layout workspace invalid: " + workspaceValidation.message);
    }

    const UIEditorWorkspaceSessionValidationResult sessionValidation =
        ValidateUIEditorWorkspaceSession(
            m_panelRegistry,
            canonicalSnapshot.workspace,
            canonicalSnapshot.session);
    if (!sessionValidation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Layout session invalid: " + sessionValidation.message);
    }

    if (AreUIEditorWorkspaceModelsEquivalent(m_workspace, canonicalSnapshot.workspace) &&
        AreUIEditorWorkspaceSessionsEquivalent(m_session, canonicalSnapshot.session)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::NoOp,
            "Current state already matches the requested layout snapshot.");
    }

    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
    const UIEditorWorkspaceSession previousSession = m_session;
    m_workspace = canonicalSnapshot.workspace;
    m_session = canonicalSnapshot.session;

    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        m_workspace = previousWorkspace;
        m_session = previousSession;
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Restored layout produced invalid controller state: " + validation.message);
    }

    return BuildLayoutOperationResult(
        UIEditorWorkspaceLayoutOperationStatus::Changed,
        "Layout restored.");
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::RestoreSerializedLayout(
    std::string_view serializedLayout) {
    const UIEditorWorkspaceLayoutLoadResult loadResult =
        DeserializeUIEditorWorkspaceLayoutSnapshot(m_panelRegistry, serializedLayout);
    if (!loadResult.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Serialized layout rejected: " + loadResult.message);
    }

    return RestoreLayoutSnapshot(loadResult.snapshot);
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::SetSplitRatio(
    std::string_view nodeId,
    float splitRatio) {
    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Controller state invalid: " + validation.message);
    }

    if (nodeId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "SetSplitRatio requires a split node id.");
    }

    const UIEditorWorkspaceNode* splitNode = FindUIEditorWorkspaceNode(m_workspace, nodeId);
    if (splitNode == nullptr || splitNode->kind != UIEditorWorkspaceNodeKind::Split) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "SetSplitRatio target split node is missing.");
    }

    if (std::fabs(splitNode->splitRatio - splitRatio) <= 0.0001f) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::NoOp,
            "Split ratio already matches the requested value.");
    }

    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
    if (!TrySetUIEditorWorkspaceSplitRatio(m_workspace, nodeId, splitRatio)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Split ratio update rejected.");
    }

    const UIEditorWorkspaceControllerValidationResult postValidation = ValidateState();
    if (!postValidation.IsValid()) {
        m_workspace = previousWorkspace;
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Split ratio update produced invalid controller state: " + postValidation.message);
    }

    return BuildLayoutOperationResult(
        UIEditorWorkspaceLayoutOperationStatus::Changed,
        "Split ratio updated.");
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::ReorderTab(
    std::string_view nodeId,
    std::string_view panelId,
    std::size_t targetVisibleInsertionIndex) {
    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Controller state invalid: " + validation.message);
    }

    if (nodeId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "ReorderTab requires a tab stack node id.");
    }

    if (panelId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "ReorderTab requires a panel id.");
    }

    const UIEditorWorkspaceNode* tabStack = FindUIEditorWorkspaceNode(m_workspace, nodeId);
    if (tabStack == nullptr || tabStack->kind != UIEditorWorkspaceNodeKind::TabStack) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "ReorderTab target tab stack is missing.");
    }

    const VisibleTabStackInfo tabInfo =
        ResolveVisibleTabStackInfo(*tabStack, m_session, panelId);
    if (!tabInfo.panelExists) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "ReorderTab target panel is missing from the specified tab stack.");
    }

    if (!tabInfo.panelVisible) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "ReorderTab only supports open and visible tabs.");
    }

    if (targetVisibleInsertionIndex > tabInfo.visibleTabCount) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "ReorderTab target visible insertion index is out of range.");
    }

    if (targetVisibleInsertionIndex == tabInfo.currentVisibleIndex ||
        targetVisibleInsertionIndex == tabInfo.currentVisibleIndex + 1u) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::NoOp,
            "Visible tab order already matches the requested insertion.");
    }

    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
    if (!TryReorderUIEditorWorkspaceTab(
            m_workspace,
            m_session,
            nodeId,
            panelId,
            targetVisibleInsertionIndex)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Tab reorder rejected.");
    }

    if (AreUIEditorWorkspaceModelsEquivalent(previousWorkspace, m_workspace)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::NoOp,
            "Visible tab order already matches the requested insertion.");
    }

    const UIEditorWorkspaceControllerValidationResult postValidation = ValidateState();
    if (!postValidation.IsValid()) {
        m_workspace = previousWorkspace;
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Tab reorder produced invalid controller state: " + postValidation.message);
    }

    return BuildLayoutOperationResult(
        UIEditorWorkspaceLayoutOperationStatus::Changed,
        "Tab reordered.");
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::MoveTabToStack(
    std::string_view sourceNodeId,
    std::string_view panelId,
    std::string_view targetNodeId,
    std::size_t targetVisibleInsertionIndex) {
    {
        std::ostringstream trace = {};
        trace << "MoveTabToStack begin sourceNode=" << sourceNodeId
              << " panel=" << panelId
              << " targetNode=" << targetNodeId
              << " insertion=" << targetVisibleInsertionIndex;
        AppendUIEditorRuntimeTrace("workspace", trace.str());
    }
    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Controller state invalid: " + validation.message);
    }

    if (sourceNodeId.empty() || targetNodeId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack requires both source and target tab stack ids.");
    }

    if (panelId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack requires a panel id.");
    }

    if (sourceNodeId == targetNodeId) {
        return ReorderTab(sourceNodeId, panelId, targetVisibleInsertionIndex);
    }

    const UIEditorWorkspaceNode* sourceTabStack =
        FindUIEditorWorkspaceNode(m_workspace, sourceNodeId);
    const UIEditorWorkspaceNode* targetTabStack =
        FindUIEditorWorkspaceNode(m_workspace, targetNodeId);
    if (sourceTabStack == nullptr ||
        targetTabStack == nullptr ||
        sourceTabStack->kind != UIEditorWorkspaceNodeKind::TabStack ||
        targetTabStack->kind != UIEditorWorkspaceNodeKind::TabStack) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack source or target tab stack is missing.");
    }

    const VisibleTabStackInfo sourceInfo =
        ResolveVisibleTabStackInfo(*sourceTabStack, m_session, panelId);
    if (!sourceInfo.panelExists) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack target panel is missing from the source tab stack.");
    }

    if (!sourceInfo.panelVisible) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack only supports open and visible tabs.");
    }

    const std::size_t visibleTargetCount = CountVisibleTabs(*targetTabStack, m_session);
    if (targetVisibleInsertionIndex > visibleTargetCount) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack target visible insertion index is out of range.");
    }

    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
    if (!TryMoveUIEditorWorkspaceTabToStack(
            m_workspace,
            m_session,
            sourceNodeId,
            panelId,
            targetNodeId,
            targetVisibleInsertionIndex)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack rejected.");
    }

    if (AreUIEditorWorkspaceModelsEquivalent(previousWorkspace, m_workspace)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::NoOp,
            "Tab already matches the requested target stack insertion.");
    }

    const UIEditorWorkspaceControllerValidationResult postValidation = ValidateState();
    if (!postValidation.IsValid()) {
        m_workspace = previousWorkspace;
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "MoveTabToStack produced invalid controller state: " + postValidation.message);
    }

    return BuildLayoutOperationResult(
        UIEditorWorkspaceLayoutOperationStatus::Changed,
        "Tab moved to target stack.");
}

UIEditorWorkspaceLayoutOperationResult UIEditorWorkspaceController::DockTabRelative(
    std::string_view sourceNodeId,
    std::string_view panelId,
    std::string_view targetNodeId,
    UIEditorWorkspaceDockPlacement placement,
    float splitRatio) {
    {
        std::ostringstream trace = {};
        trace << "DockTabRelative begin sourceNode=" << sourceNodeId
              << " panel=" << panelId
              << " targetNode=" << targetNodeId
              << " placement=" << static_cast<int>(placement)
              << " splitRatio=" << splitRatio;
        AppendUIEditorRuntimeTrace("workspace", trace.str());
    }
    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (!validation.IsValid()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "Controller state invalid: " + validation.message);
    }

    if (sourceNodeId.empty() || targetNodeId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative requires both source and target tab stack ids.");
    }

    if (panelId.empty()) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative requires a panel id.");
    }

    const UIEditorWorkspaceNode* sourceTabStack =
        FindUIEditorWorkspaceNode(m_workspace, sourceNodeId);
    const UIEditorWorkspaceNode* targetTabStack =
        FindUIEditorWorkspaceNode(m_workspace, targetNodeId);
    if (sourceTabStack == nullptr ||
        targetTabStack == nullptr ||
        sourceTabStack->kind != UIEditorWorkspaceNodeKind::TabStack ||
        targetTabStack->kind != UIEditorWorkspaceNodeKind::TabStack) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative source or target tab stack is missing.");
    }

    const VisibleTabStackInfo sourceInfo =
        ResolveVisibleTabStackInfo(*sourceTabStack, m_session, panelId);
    if (!sourceInfo.panelExists) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative target panel is missing from the source tab stack.");
    }

    if (!sourceInfo.panelVisible) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative only supports open and visible tabs.");
    }

    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
    if (!TryDockUIEditorWorkspaceTabRelative(
            m_workspace,
            m_session,
            sourceNodeId,
            panelId,
            targetNodeId,
            placement,
            splitRatio)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative rejected.");
    }

    if (AreUIEditorWorkspaceModelsEquivalent(previousWorkspace, m_workspace)) {
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::NoOp,
            "Dock layout already matches the requested placement.");
    }

    const UIEditorWorkspaceControllerValidationResult postValidation = ValidateState();
    if (!postValidation.IsValid()) {
        m_workspace = previousWorkspace;
        return BuildLayoutOperationResult(
            UIEditorWorkspaceLayoutOperationStatus::Rejected,
            "DockTabRelative produced invalid controller state: " + postValidation.message);
    }

    return BuildLayoutOperationResult(
        UIEditorWorkspaceLayoutOperationStatus::Changed,
        "Tab docked relative to target stack.");
}

UIEditorWorkspaceCommandResult UIEditorWorkspaceController::Dispatch(
    const UIEditorWorkspaceCommand& command) {
    const UIEditorWorkspaceControllerValidationResult validation = ValidateState();
    if (command.kind != UIEditorWorkspaceCommandKind::ResetWorkspace &&
        !validation.IsValid()) {
        return BuildResult(
            command,
            UIEditorWorkspaceCommandStatus::Rejected,
            "Controller state invalid: " + validation.message);
    }

    const UIEditorWorkspaceModel previousWorkspace = m_workspace;
    const UIEditorWorkspaceSession previousSession = m_session;
    const UIEditorPanelSessionState* panelState =
        command.kind == UIEditorWorkspaceCommandKind::ResetWorkspace
            ? nullptr
            : FindUIEditorPanelSessionState(m_session, command.panelId);
    const UIEditorPanelDescriptor* panelDescriptor =
        command.kind == UIEditorWorkspaceCommandKind::ResetWorkspace
            ? nullptr
            : FindPanelDescriptor(command.panelId);

    switch (command.kind) {
    case UIEditorWorkspaceCommandKind::OpenPanel:
        if (command.panelId.empty()) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "OpenPanel requires a panelId.");
        }
        if (panelDescriptor == nullptr || panelState == nullptr) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "OpenPanel target panel is missing.");
        }
        if (panelState->open && panelState->visible) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Panel is already open and visible.");
        }
        return FinalizeMutation(
            command,
            TryOpenUIEditorWorkspacePanel(m_panelRegistry, m_workspace, m_session, command.panelId),
            "Panel opened and activated.",
            "OpenPanel failed unexpectedly.",
            previousWorkspace,
            previousSession);

    case UIEditorWorkspaceCommandKind::ClosePanel:
        if (command.panelId.empty()) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "ClosePanel requires a panelId.");
        }
        if (panelDescriptor == nullptr || panelState == nullptr) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "ClosePanel target panel is missing.");
        }
        if (!panelDescriptor->canClose) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "Panel cannot be closed.");
        }
        if (!panelState->open) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Panel is already closed.");
        }
        return FinalizeMutation(
            command,
            TryCloseUIEditorWorkspacePanel(m_panelRegistry, m_workspace, m_session, command.panelId),
            "Panel closed.",
            "ClosePanel failed unexpectedly.",
            previousWorkspace,
            previousSession);

    case UIEditorWorkspaceCommandKind::ShowPanel:
        if (command.panelId.empty()) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "ShowPanel requires a panelId.");
        }
        if (panelDescriptor == nullptr || panelState == nullptr) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "ShowPanel target panel is missing.");
        }
        if (!panelState->open) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "Closed panel must be opened before it can be shown.");
        }
        if (panelState->visible) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Panel is already visible.");
        }
        return FinalizeMutation(
            command,
            TryShowUIEditorWorkspacePanel(m_panelRegistry, m_workspace, m_session, command.panelId),
            "Panel shown and activated.",
            "ShowPanel failed unexpectedly.",
            previousWorkspace,
            previousSession);

    case UIEditorWorkspaceCommandKind::HidePanel:
        if (command.panelId.empty()) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "HidePanel requires a panelId.");
        }
        if (panelDescriptor == nullptr || panelState == nullptr) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "HidePanel target panel is missing.");
        }
        if (!panelDescriptor->canHide) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "Panel cannot be hidden.");
        }
        if (!panelState->open) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "Closed panel cannot be hidden.");
        }
        if (!panelState->visible) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Panel is already hidden.");
        }
        return FinalizeMutation(
            command,
            TryHideUIEditorWorkspacePanel(m_panelRegistry, m_workspace, m_session, command.panelId),
            "Panel hidden and active panel re-resolved.",
            "HidePanel failed unexpectedly.",
            previousWorkspace,
            previousSession);

    case UIEditorWorkspaceCommandKind::ActivatePanel:
        if (command.panelId.empty()) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "ActivatePanel requires a panelId.");
        }
        if (panelDescriptor == nullptr || panelState == nullptr) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "ActivatePanel target panel is missing.");
        }
        if (!panelState->open || !panelState->visible) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "Only open and visible panels can be activated.");
        }
        if (m_workspace.activePanelId == command.panelId) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Panel is already active.");
        }
        return FinalizeMutation(
            command,
            TryActivateUIEditorWorkspacePanel(m_panelRegistry, m_workspace, m_session, command.panelId),
            "Panel activated.",
            "ActivatePanel failed unexpectedly.",
            previousWorkspace,
            previousSession);

    case UIEditorWorkspaceCommandKind::ResetWorkspace:
        if (AreUIEditorWorkspaceModelsEquivalent(m_workspace, m_baselineWorkspace) &&
            AreUIEditorWorkspaceSessionsEquivalent(m_session, m_baselineSession)) {
            return BuildResult(command, UIEditorWorkspaceCommandStatus::NoOp, "Workspace already matches the baseline state.");
        }

        m_workspace = m_baselineWorkspace;
        m_session = m_baselineSession;
        return FinalizeMutation(
            command,
            true,
            "Workspace reset to baseline.",
            "ResetWorkspace failed unexpectedly.",
            previousWorkspace,
            previousSession);
    }

    return BuildResult(command, UIEditorWorkspaceCommandStatus::Rejected, "Unknown command kind.");
}

UIEditorWorkspaceController BuildDefaultUIEditorWorkspaceController(
    const UIEditorPanelRegistry& panelRegistry,
    const UIEditorWorkspaceModel& workspace) {
    const UIEditorWorkspaceModel canonicalWorkspace =
        CanonicalizeUIEditorWorkspaceModel(workspace);
    return UIEditorWorkspaceController(
        panelRegistry,
        canonicalWorkspace,
        BuildDefaultUIEditorWorkspaceSession(panelRegistry, canonicalWorkspace));
}

} // namespace XCEngine::UI::Editor