#include <XCNewEditor/Editor/UIEditorWorkspaceController.h>

#include <utility>

namespace XCEngine::NewEditor {

namespace {

bool AreWorkspaceNodesEquivalent(
    const UIEditorWorkspaceNode& lhs,
    const UIEditorWorkspaceNode& rhs) {
    if (lhs.kind != rhs.kind ||
        lhs.nodeId != rhs.nodeId ||
        lhs.splitAxis != rhs.splitAxis ||
        lhs.splitRatio != rhs.splitRatio ||
        lhs.selectedTabIndex != rhs.selectedTabIndex ||
        lhs.panel.panelId != rhs.panel.panelId ||
        lhs.panel.title != rhs.panel.title ||
        lhs.panel.placeholder != rhs.panel.placeholder ||
        lhs.children.size() != rhs.children.size()) {
        return false;
    }

    for (std::size_t index = 0; index < lhs.children.size(); ++index) {
        if (!AreWorkspaceNodesEquivalent(lhs.children[index], rhs.children[index])) {
            return false;
        }
    }

    return true;
}

bool AreWorkspaceModelsEquivalent(
    const UIEditorWorkspaceModel& lhs,
    const UIEditorWorkspaceModel& rhs) {
    return lhs.activePanelId == rhs.activePanelId &&
        AreWorkspaceNodesEquivalent(lhs.root, rhs.root);
}

bool AreWorkspaceSessionsEquivalent(
    const UIEditorWorkspaceSession& lhs,
    const UIEditorWorkspaceSession& rhs) {
    if (lhs.panelStates.size() != rhs.panelStates.size()) {
        return false;
    }

    for (std::size_t index = 0; index < lhs.panelStates.size(); ++index) {
        const UIEditorPanelSessionState& lhsState = lhs.panelStates[index];
        const UIEditorPanelSessionState& rhsState = rhs.panelStates[index];
        if (lhsState.panelId != rhsState.panelId ||
            lhsState.open != rhsState.open ||
            lhsState.visible != rhsState.visible) {
            return false;
        }
    }

    return true;
}

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;
}

} // 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";
}

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

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;
}

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);
}

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 (AreWorkspaceModelsEquivalent(m_workspace, m_baselineWorkspace) &&
            AreWorkspaceSessionsEquivalent(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) {
    return UIEditorWorkspaceController(
        panelRegistry,
        workspace,
        BuildDefaultUIEditorWorkspaceSession(panelRegistry, workspace));
}

} // namespace XCEngine::NewEditor