#include <XCEditor/Fields/UIEditorVector3FieldInteraction.h>

#include <XCEngine/Input/InputTypes.h>

#include <algorithm>
#include <utility>

namespace XCEngine::UI::Editor {

namespace {

using ::XCEngine::Input::KeyCode;
using ::XCEngine::UI::UIInputEvent;
using ::XCEngine::UI::UIInputEventType;
using ::XCEngine::UI::UIPointerButton;
using ::XCEngine::UI::Editor::Widgets::BuildUIEditorVector3FieldLayout;
using ::XCEngine::UI::Editor::Widgets::FormatUIEditorVector3FieldComponentValue;
using ::XCEngine::UI::Editor::Widgets::HitTestUIEditorVector3Field;
using ::XCEngine::UI::Editor::Widgets::IsUIEditorVector3FieldPointInside;
using ::XCEngine::UI::Editor::Widgets::NormalizeUIEditorVector3FieldComponentValue;
using ::XCEngine::UI::Editor::Widgets::TryParseUIEditorVector3FieldComponentValue;
using ::XCEngine::UI::Editor::Widgets::UIEditorVector3FieldHitTarget;
using ::XCEngine::UI::Editor::Widgets::UIEditorVector3FieldHitTargetKind;
using ::XCEngine::UI::Editor::Widgets::UIEditorVector3FieldInvalidComponentIndex;
using ::XCEngine::UI::Editor::Widgets::UIEditorVector3FieldLayout;
using ::XCEngine::UI::Editor::Widgets::UIEditorVector3FieldMetrics;
using ::XCEngine::UI::Editor::Widgets::UIEditorVector3FieldSpec;

constexpr std::size_t kComponentCount = 3u;
constexpr std::size_t kLastComponentIndex = 2u;

bool IsPermittedCharacter(
    const UIEditorVector3FieldSpec& spec,
    std::uint32_t character) {
    if (character >= static_cast<std::uint32_t>('0') &&
        character <= static_cast<std::uint32_t>('9')) {
        return true;
    }
    if (character == static_cast<std::uint32_t>('-') ||
        character == static_cast<std::uint32_t>('+')) {
        return true;
    }
    return !spec.integerMode && character == static_cast<std::uint32_t>('.');
}

std::size_t ResolveSelectedComponentIndex(
    const UIEditorVector3FieldInteractionState& state) {
    return state.vector3FieldState.selectedComponentIndex ==
            UIEditorVector3FieldInvalidComponentIndex
        ? 0u
        : state.vector3FieldState.selectedComponentIndex;
}

double ResolveDragSensitivity(const UIEditorVector3FieldSpec& spec) {
    if (spec.step != 0.0) {
        return spec.step;
    }

    return spec.integerMode ? 1.0 : 0.1;
}

void SyncDisplayState(
    UIEditorVector3FieldInteractionState& state,
    const UIEditorVector3FieldSpec& spec,
    const UIEditorVector3FieldLayout& layout) {
    auto& fieldState = state.vector3FieldState;
    const auto& session = state.session;
    fieldState.focused = session.focused;
    fieldState.editing = session.editing;
    fieldState.caretBlinkStartNanoseconds = session.caretBlinkStartNanoseconds;
    for (std::size_t componentIndex = 0u; componentIndex < kComponentCount;
         ++componentIndex) {
        fieldState.displayTexts[componentIndex] =
            session.editing &&
                fieldState.selectedComponentIndex == componentIndex
            ? session.textInputState.value
            : FormatUIEditorVector3FieldComponentValue(spec, componentIndex);
    }
    if (session.editing &&
        fieldState.selectedComponentIndex !=
            UIEditorVector3FieldInvalidComponentIndex) {
        fieldState.caretOffset = session.textInputState.caret;
    } else if (fieldState.selectedComponentIndex !=
               UIEditorVector3FieldInvalidComponentIndex) {
        fieldState.caretOffset =
            fieldState.displayTexts[fieldState.selectedComponentIndex].size();
    } else {
        fieldState.caretOffset = 0u;
    }
    if (!session.hasPointerPosition) {
        fieldState.hoveredTarget = UIEditorVector3FieldHitTargetKind::None;
        fieldState.hoveredComponentIndex =
            UIEditorVector3FieldInvalidComponentIndex;
        return;
    }

    const UIEditorVector3FieldHitTarget hitTarget =
        HitTestUIEditorVector3Field(layout, session.pointerPosition);
    fieldState.hoveredTarget = hitTarget.kind;
    fieldState.hoveredComponentIndex = hitTarget.componentIndex;
}

bool SelectComponent(
    UIEditorVector3FieldInteractionState& state,
    std::size_t componentIndex,
    UIEditorVector3FieldInteractionResult& result) {
    if (componentIndex >= kComponentCount) {
        return false;
    }

    const std::size_t before = ResolveSelectedComponentIndex(state);
    state.vector3FieldState.selectedComponentIndex = componentIndex;
    state.session.activeComponentIndex = componentIndex;
    result.selectionChanged = before != componentIndex;
    result.selectedComponentIndex = componentIndex;
    return true;
}

bool MoveSelection(
    UIEditorVector3FieldInteractionState& state,
    int direction,
    UIEditorVector3FieldInteractionResult& result) {
    const std::size_t before = ResolveSelectedComponentIndex(state);
    const std::size_t after = direction < 0
        ? (before == 0u ? 0u : before - 1u)
        : (before >= kLastComponentIndex ? kLastComponentIndex : before + 1u);
    state.vector3FieldState.selectedComponentIndex = after;
    state.session.activeComponentIndex = after;
    result.selectionChanged = before != after;
    result.selectedComponentIndex = after;
    result.consumed = true;
    return true;
}

bool BeginEdit(
    UIEditorVector3FieldInteractionState& state,
    const UIEditorVector3FieldSpec& spec,
    std::size_t componentIndex,
    bool clearText) {
    if (spec.readOnly || componentIndex >= spec.values.size()) {
        return false;
    }

    state.vector3FieldState.selectedComponentIndex = componentIndex;
    return BeginUIEditorEditableFieldEdit(
        state.session,
        spec.fieldId,
        componentIndex,
        FormatUIEditorVector3FieldComponentValue(spec, componentIndex),
        clearText);
}

bool CommitEdit(
    UIEditorVector3FieldInteractionState& state,
    UIEditorVector3FieldSpec& spec,
    UIEditorVector3FieldInteractionResult& result) {
    const std::size_t componentIndex =
        state.vector3FieldState.selectedComponentIndex;
    if (!state.session.editing || componentIndex >= spec.values.size()) {
        return false;
    }

    double parsedValue = spec.values[componentIndex];
    if (!TryParseUIEditorVector3FieldComponentValue(
            spec,
            state.session.textInputState.value,
            parsedValue)) {
        result.consumed = true;
        result.editCommitRejected = true;
        return false;
    }

    result.valuesBefore = spec.values;
    spec.values[componentIndex] =
        NormalizeUIEditorVector3FieldComponentValue(spec, parsedValue);
    result.valuesAfter = spec.values;
    result.valueChanged = result.valuesBefore != result.valuesAfter;
    result.editCommitted = true;
    result.consumed = true;
    result.changedComponentIndex = componentIndex;
    result.selectedComponentIndex = componentIndex;
    result.committedText =
        FormatUIEditorVector3FieldComponentValue(spec, componentIndex);
    CommitUIEditorEditableFieldEdit(state.session);
    return true;
}

bool CancelEdit(
    UIEditorVector3FieldInteractionState& state,
    const UIEditorVector3FieldSpec& spec,
    UIEditorVector3FieldInteractionResult& result) {
    const std::size_t componentIndex =
        state.vector3FieldState.selectedComponentIndex;
    if (!state.session.editing || componentIndex >= spec.values.size()) {
        return false;
    }

    CancelUIEditorEditableFieldEdit(state.session);
    result.consumed = true;
    result.editCanceled = true;
    result.valuesBefore = spec.values;
    result.valuesAfter = spec.values;
    result.selectedComponentIndex = componentIndex;
    return true;
}

bool ApplyStep(
    UIEditorVector3FieldInteractionState& state,
    UIEditorVector3FieldSpec& spec,
    double direction,
    bool snapToEdge,
    UIEditorVector3FieldInteractionResult& result) {
    if (spec.readOnly) {
        return false;
    }

    const std::size_t componentIndex = ResolveSelectedComponentIndex(state);
    state.vector3FieldState.selectedComponentIndex = componentIndex;
    state.session.activeComponentIndex = componentIndex;
    if (state.session.editing && !CommitEdit(state, spec, result)) {
        return result.editCommitRejected;
    }

    result.valuesBefore = spec.values;
    if (snapToEdge) {
        spec.values[componentIndex] = direction < 0.0
            ? NormalizeUIEditorVector3FieldComponentValue(spec, spec.minValue)
            : NormalizeUIEditorVector3FieldComponentValue(spec, spec.maxValue);
    } else {
        const double step = spec.step == 0.0 ? 1.0 : spec.step;
        spec.values[componentIndex] =
            NormalizeUIEditorVector3FieldComponentValue(
                spec,
                spec.values[componentIndex] + step * direction);
        result.stepDelta = step * direction;
    }

    result.valuesAfter = spec.values;
    result.stepApplied = true;
    result.valueChanged = result.valuesBefore != result.valuesAfter;
    result.changedComponentIndex = componentIndex;
    result.selectedComponentIndex = componentIndex;
    result.consumed = true;
    return true;
}

bool ApplyDrag(
    UIEditorVector3FieldInteractionState& state,
    UIEditorVector3FieldSpec& spec,
    std::size_t componentIndex,
    UIEditorVector3FieldInteractionResult& result) {
    if (spec.readOnly || state.session.editing ||
        componentIndex >= spec.values.size()) {
        return false;
    }

    result.valuesBefore = spec.values;
    spec.values[componentIndex] =
        NormalizeUIEditorVector3FieldComponentValue(
            spec,
            state.session.dragStartValue +
                ResolveUIEditorEditableFieldDragDelta(
                    state.session,
                    ResolveDragSensitivity(spec)));
    result.valuesAfter = spec.values;
    result.valueChanged = result.valuesBefore != result.valuesAfter;
    result.changedComponentIndex = componentIndex;
    result.selectedComponentIndex = componentIndex;
    result.consumed = true;
    return true;
}

} // namespace

UIEditorVector3FieldInteractionFrame UpdateUIEditorVector3FieldInteraction(
    UIEditorVector3FieldInteractionState& state,
    UIEditorVector3FieldSpec& spec,
    const ::XCEngine::UI::UIRect& bounds,
    const std::vector<UIInputEvent>& inputEvents,
    const UIEditorVector3FieldMetrics& metrics) {
    UIEditorVector3FieldLayout layout = BuildUIEditorVector3FieldLayout(
        bounds,
        spec,
        metrics);
    SyncDisplayState(state, spec, layout);

    UIEditorVector3FieldInteractionResult interactionResult = {};
    interactionResult.selectedComponentIndex =
        state.vector3FieldState.selectedComponentIndex;
    for (const UIInputEvent& event : inputEvents) {
        UpdateUIEditorEditableFieldPointerPosition(state.session, event);

        UIEditorVector3FieldInteractionResult eventResult = {};
        eventResult.selectedComponentIndex =
            state.vector3FieldState.selectedComponentIndex;
        switch (event.type) {
        case UIInputEventType::FocusGained:
            eventResult.focusChanged = !state.session.focused;
            state.session.focused = true;
            if (state.vector3FieldState.selectedComponentIndex ==
                UIEditorVector3FieldInvalidComponentIndex) {
                state.vector3FieldState.selectedComponentIndex = 0u;
            }
            state.session.activeComponentIndex =
                state.vector3FieldState.selectedComponentIndex;
            eventResult.selectedComponentIndex =
                state.vector3FieldState.selectedComponentIndex;
            break;

        case UIInputEventType::FocusLost:
            eventResult.focusChanged = state.session.focused;
            state.session.focused = false;
            state.vector3FieldState.activeTarget =
                UIEditorVector3FieldHitTargetKind::None;
            state.vector3FieldState.activeComponentIndex =
                UIEditorVector3FieldInvalidComponentIndex;
            state.session.hasPointerPosition = false;
            EndUIEditorEditableFieldDrag(state.session);
            if (state.session.editing) {
                CommitEdit(state, spec, eventResult);
                if (eventResult.editCommitRejected) {
                    CancelEdit(state, spec, eventResult);
                }
            }
            break;

        case UIInputEventType::PointerMove:
            TryActivateUIEditorEditableFieldDrag(state.session, event);
            if (state.session.dragActive &&
                state.vector3FieldState.activeTarget ==
                    UIEditorVector3FieldHitTargetKind::Component &&
                state.vector3FieldState.activeComponentIndex !=
                    UIEditorVector3FieldInvalidComponentIndex) {
                ApplyDrag(
                    state,
                    spec,
                    state.vector3FieldState.activeComponentIndex,
                    eventResult);
            }
            break;

        case UIInputEventType::PointerEnter:
        case UIInputEventType::PointerLeave:
            break;

        case UIInputEventType::PointerButtonDown: {
            const UIEditorVector3FieldHitTarget hitTarget =
                state.session.hasPointerPosition
                    ? HitTestUIEditorVector3Field(
                          layout,
                          state.session.pointerPosition)
                    : UIEditorVector3FieldHitTarget {};
            eventResult.hitTarget = hitTarget;

            if (event.pointerButton != UIPointerButton::Left) {
                break;
            }

            const bool insideField =
                state.session.hasPointerPosition &&
                IsUIEditorVector3FieldPointInside(
                    layout.bounds,
                    state.session.pointerPosition);
            if (insideField) {
                eventResult.focusChanged = !state.session.focused;
                state.session.focused = true;
                state.vector3FieldState.activeTarget =
                    hitTarget.kind == UIEditorVector3FieldHitTargetKind::None
                        ? UIEditorVector3FieldHitTargetKind::Row
                        : hitTarget.kind;
                state.vector3FieldState.activeComponentIndex =
                    hitTarget.componentIndex;
                if (hitTarget.kind ==
                        UIEditorVector3FieldHitTargetKind::Component &&
                    !state.session.editing) {
                    ArmUIEditorEditableFieldDrag(
                        state.session,
                        spec.fieldId,
                        hitTarget.componentIndex,
                        hitTarget.componentIndex < spec.values.size()
                            ? spec.values[hitTarget.componentIndex]
                            : 0.0);
                    SelectComponent(state, hitTarget.componentIndex, eventResult);
                } else {
                    EndUIEditorEditableFieldDrag(state.session);
                    if (state.vector3FieldState.selectedComponentIndex ==
                        UIEditorVector3FieldInvalidComponentIndex) {
                        state.vector3FieldState.selectedComponentIndex = 0u;
                        state.session.activeComponentIndex = 0u;
                        eventResult.selectedComponentIndex = 0u;
                    }
                }
                eventResult.consumed = true;
            } else {
                if (state.session.editing) {
                    CommitEdit(state, spec, eventResult);
                    if (!eventResult.editCommitRejected) {
                        eventResult.focusChanged = state.session.focused;
                        state.session.focused = false;
                    }
                } else if (state.session.focused) {
                    eventResult.focusChanged = true;
                    state.session.focused = false;
                }
                state.vector3FieldState.activeTarget =
                    UIEditorVector3FieldHitTargetKind::None;
                state.vector3FieldState.activeComponentIndex =
                    UIEditorVector3FieldInvalidComponentIndex;
                EndUIEditorEditableFieldDrag(state.session);
            }
            break;
        }

        case UIInputEventType::PointerButtonUp: {
            const UIEditorVector3FieldHitTarget hitTarget =
                state.session.hasPointerPosition
                    ? HitTestUIEditorVector3Field(
                          layout,
                          state.session.pointerPosition)
                    : UIEditorVector3FieldHitTarget {};
            eventResult.hitTarget = hitTarget;

            if (event.pointerButton == UIPointerButton::Left) {
                const UIEditorVector3FieldHitTargetKind activeTarget =
                    state.vector3FieldState.activeTarget;
                const std::size_t activeComponentIndex =
                    state.vector3FieldState.activeComponentIndex;
                state.vector3FieldState.activeTarget =
                    UIEditorVector3FieldHitTargetKind::None;
                state.vector3FieldState.activeComponentIndex =
                    UIEditorVector3FieldInvalidComponentIndex;

                if (activeTarget == UIEditorVector3FieldHitTargetKind::Component &&
                    hitTarget.kind == UIEditorVector3FieldHitTargetKind::Component &&
                    activeComponentIndex == hitTarget.componentIndex) {
                    SelectComponent(state, hitTarget.componentIndex, eventResult);
                    if (state.session.dragActive) {
                        eventResult.consumed = true;
                    } else if (!state.session.editing &&
                               IsUIEditorEditableFieldDoubleClick(
                                   state.session,
                                   spec.fieldId,
                                   event,
                                   hitTarget.componentIndex)) {
                        eventResult.editStarted =
                            BeginEdit(state, spec, hitTarget.componentIndex, false);
                        eventResult.consumed = true;
                    } else {
                        RecordUIEditorEditableFieldClick(
                            state.session,
                            spec.fieldId,
                            event,
                            hitTarget.componentIndex);
                        eventResult.consumed = true;
                    }
                } else if (hitTarget.kind == UIEditorVector3FieldHitTargetKind::Row) {
                    eventResult.consumed = true;
                }

                EndUIEditorEditableFieldDrag(state.session);
            }
            break;
        }

        case UIInputEventType::KeyDown:
            if (!state.session.focused) {
                break;
            }

            if (state.session.editing) {
                if (event.keyCode == static_cast<std::int32_t>(KeyCode::Escape)) {
                    CancelEdit(state, spec, eventResult);
                    break;
                }
                if (event.keyCode == static_cast<std::int32_t>(KeyCode::Tab)) {
                    if (CommitEdit(state, spec, eventResult)) {
                        MoveSelection(
                            state,
                            event.modifiers.shift ? -1 : 1,
                            eventResult);
                    }
                    eventResult.consumed = true;
                    break;
                }

                const auto textResult = HandleUIEditorEditableFieldKeyDown(
                    state.session,
                    event.keyCode,
                    event.modifiers);
                if (textResult.handled) {
                    eventResult.consumed = true;
                    eventResult.selectedComponentIndex =
                        state.vector3FieldState.selectedComponentIndex;
                    if (textResult.submitRequested) {
                        CommitEdit(state, spec, eventResult);
                    }
                }
            } else {
                switch (static_cast<KeyCode>(event.keyCode)) {
                case KeyCode::Left:
                    MoveSelection(state, -1, eventResult);
                    break;
                case KeyCode::Right:
                case KeyCode::Tab:
                    MoveSelection(
                        state,
                        static_cast<KeyCode>(event.keyCode) == KeyCode::Tab &&
                                event.modifiers.shift
                            ? -1
                            : 1,
                        eventResult);
                    break;
                case KeyCode::Up:
                    ApplyStep(state, spec, 1.0, false, eventResult);
                    break;
                case KeyCode::Down:
                    ApplyStep(state, spec, -1.0, false, eventResult);
                    break;
                case KeyCode::Home:
                    ApplyStep(state, spec, -1.0, true, eventResult);
                    break;
                case KeyCode::End:
                    ApplyStep(state, spec, 1.0, true, eventResult);
                    break;
                case KeyCode::Enter:
                    eventResult.selectedComponentIndex =
                        ResolveSelectedComponentIndex(state);
                    eventResult.editStarted = BeginEdit(
                        state,
                        spec,
                        eventResult.selectedComponentIndex,
                        false);
                    eventResult.consumed = eventResult.editStarted;
                    break;
                default:
                    break;
                }
            }
            break;

        case UIInputEventType::Character:
            if (!state.session.focused ||
                spec.readOnly ||
                event.modifiers.control ||
                event.modifiers.alt ||
                event.modifiers.super ||
                !IsPermittedCharacter(spec, event.character)) {
                break;
            }

            if (state.vector3FieldState.selectedComponentIndex ==
                UIEditorVector3FieldInvalidComponentIndex) {
                state.vector3FieldState.selectedComponentIndex = 0u;
            }
            state.session.activeComponentIndex =
                state.vector3FieldState.selectedComponentIndex;
            eventResult.selectedComponentIndex =
                state.vector3FieldState.selectedComponentIndex;
            if (!state.session.editing) {
                eventResult.editStarted = BeginEdit(
                    state,
                    spec,
                    state.vector3FieldState.selectedComponentIndex,
                    true);
            }
            if (InsertUIEditorEditableFieldCharacter(
                    state.session,
                    event.character)) {
                eventResult.consumed = true;
            }
            break;

        default:
            break;
        }

        layout = BuildUIEditorVector3FieldLayout(bounds, spec, metrics);
        SyncDisplayState(state, spec, layout);
        if (eventResult.hitTarget.kind == UIEditorVector3FieldHitTargetKind::None &&
            state.session.hasPointerPosition) {
            eventResult.hitTarget = HitTestUIEditorVector3Field(
                layout,
                state.session.pointerPosition);
        }
        if (eventResult.selectedComponentIndex ==
            UIEditorVector3FieldInvalidComponentIndex) {
            eventResult.selectedComponentIndex =
                state.vector3FieldState.selectedComponentIndex;
        }

        if (eventResult.consumed ||
            eventResult.focusChanged ||
            eventResult.valueChanged ||
            eventResult.stepApplied ||
            eventResult.selectionChanged ||
            eventResult.editStarted ||
            eventResult.editCommitted ||
            eventResult.editCommitRejected ||
            eventResult.editCanceled ||
            eventResult.hitTarget.kind !=
                UIEditorVector3FieldHitTargetKind::None) {
            interactionResult = std::move(eventResult);
        }
    }

    layout = BuildUIEditorVector3FieldLayout(bounds, spec, metrics);
    SyncDisplayState(state, spec, layout);
    if (interactionResult.hitTarget.kind == UIEditorVector3FieldHitTargetKind::None &&
        state.session.hasPointerPosition) {
        interactionResult.hitTarget = HitTestUIEditorVector3Field(
            layout,
            state.session.pointerPosition);
    }
    if (interactionResult.selectedComponentIndex ==
        UIEditorVector3FieldInvalidComponentIndex) {
        interactionResult.selectedComponentIndex =
            state.vector3FieldState.selectedComponentIndex;
    }

    return {
        std::move(layout),
        std::move(interactionResult)
    };
}

} // namespace XCEngine::UI::Editor