#include <XCEditor/Widgets/UIEditorPanelFrame.h>

#include <algorithm>
#include <string>

namespace XCEngine::UI::Editor::Widgets {

namespace {

using ::XCEngine::UI::UIColor;
using ::XCEngine::UI::UIDrawList;
using ::XCEngine::UI::UIPoint;
using ::XCEngine::UI::UIRect;

float ClampNonNegative(float value) {
    return (std::max)(value, 0.0f);
}

float ResolveActionButtonExtent(
    const UIEditorPanelFrameMetrics& metrics,
    float headerHeight) {
    const float inset = (std::max)(metrics.actionInsetX, 0.0f);
    return (std::min)(
        (std::max)(metrics.actionButtonExtent, 0.0f),
        (std::max)(headerHeight - inset * 2.0f, 0.0f));
}

UIColor ResolveActionFillColor(
    bool selected,
    bool hovered,
    const UIEditorPanelFramePalette& palette) {
    if (selected) {
        return palette.actionButtonSelectedColor;
    }

    if (hovered) {
        return palette.actionButtonHoveredColor;
    }

    return palette.actionButtonColor;
}

void AppendActionButton(
    UIDrawList& drawList,
    const UIRect& rect,
    std::string_view glyph,
    bool selected,
    bool hovered,
    const UIEditorPanelFramePalette& palette) {
    if (rect.width <= 0.0f || rect.height <= 0.0f) {
        return;
    }

    drawList.AddFilledRect(
        rect,
        ResolveActionFillColor(selected, hovered, palette),
        5.0f);
    drawList.AddRectOutline(
        rect,
        palette.actionButtonBorderColor,
        1.0f,
        5.0f);
    drawList.AddText(
        UIPoint(rect.x + 5.0f, rect.y + 2.0f),
        std::string(glyph),
        palette.actionGlyphColor,
        12.0f);
}

} // namespace

bool IsUIEditorPanelFramePointInside(
    const UIRect& rect,
    const UIPoint& point) {
    return point.x >= rect.x &&
        point.x <= rect.x + rect.width &&
        point.y >= rect.y &&
        point.y <= rect.y + rect.height;
}

bool IsUIEditorPanelFramePinButtonVisible(const UIEditorPanelFrameState& state) {
    return state.pinnable;
}

bool IsUIEditorPanelFrameCloseButtonVisible(const UIEditorPanelFrameState& state) {
    return state.closable;
}

UIEditorPanelFrameLayout BuildUIEditorPanelFrameLayout(
    const UIRect& frameRect,
    const UIEditorPanelFrameState& state,
    const UIEditorPanelFrameMetrics& metrics) {
    UIEditorPanelFrameLayout layout = {};
    layout.frameRect = UIRect(
        frameRect.x,
        frameRect.y,
        ClampNonNegative(frameRect.width),
        ClampNonNegative(frameRect.height));

    const float headerHeight =
        (std::min)(ClampNonNegative(metrics.headerHeight), layout.frameRect.height);
    const float footerHeight =
        state.showFooter
            ? (std::min)(
                ClampNonNegative(metrics.footerHeight),
                (std::max)(layout.frameRect.height - headerHeight, 0.0f))
            : 0.0f;

    layout.hasFooter = footerHeight > 0.0f;
    layout.showPinButton = IsUIEditorPanelFramePinButtonVisible(state);
    layout.showCloseButton = IsUIEditorPanelFrameCloseButtonVisible(state);

    layout.headerRect = UIRect(
        layout.frameRect.x,
        layout.frameRect.y,
        layout.frameRect.width,
        headerHeight);

    if (layout.hasFooter) {
        layout.footerRect = UIRect(
            layout.frameRect.x,
            layout.frameRect.y + layout.frameRect.height - footerHeight,
            layout.frameRect.width,
            footerHeight);
    }

    const float bodyBandTop = layout.headerRect.y + layout.headerRect.height;
    const float bodyBandBottom = layout.hasFooter
        ? layout.footerRect.y
        : layout.frameRect.y + layout.frameRect.height;
    const float contentPadding = ClampNonNegative(metrics.contentPadding);

    layout.bodyRect = UIRect(
        layout.frameRect.x + contentPadding,
        bodyBandTop + contentPadding,
        (std::max)(layout.frameRect.width - contentPadding * 2.0f, 0.0f),
        (std::max)(bodyBandBottom - bodyBandTop - contentPadding * 2.0f, 0.0f));

    if (layout.headerRect.height <= 0.0f) {
        return layout;
    }

    const float buttonExtent = ResolveActionButtonExtent(metrics, layout.headerRect.height);
    if (buttonExtent <= 0.0f) {
        return layout;
    }

    const float buttonY = layout.headerRect.y + (layout.headerRect.height - buttonExtent) * 0.5f;
    float buttonRight = layout.headerRect.x + layout.headerRect.width - ClampNonNegative(metrics.actionInsetX);

    if (layout.showCloseButton) {
        layout.closeButtonRect = UIRect(
            buttonRight - buttonExtent,
            buttonY,
            buttonExtent,
            buttonExtent);
        buttonRight = layout.closeButtonRect.x - ClampNonNegative(metrics.actionGap);
    }

    if (layout.showPinButton) {
        layout.pinButtonRect = UIRect(
            buttonRight - buttonExtent,
            buttonY,
            buttonExtent,
            buttonExtent);
    }

    return layout;
}

UIColor ResolveUIEditorPanelFrameBorderColor(
    const UIEditorPanelFrameState& state,
    const UIEditorPanelFramePalette& palette) {
    if (state.focused) {
        return palette.focusedBorderColor;
    }

    if (state.active) {
        return palette.activeBorderColor;
    }

    if (state.hovered) {
        return palette.hoveredBorderColor;
    }

    return palette.borderColor;
}

float ResolveUIEditorPanelFrameBorderThickness(
    const UIEditorPanelFrameState& state,
    const UIEditorPanelFrameMetrics& metrics) {
    if (state.focused) {
        return metrics.focusedBorderThickness;
    }

    if (state.active) {
        return metrics.activeBorderThickness;
    }

    if (state.hovered) {
        return metrics.hoveredBorderThickness;
    }

    return metrics.baseBorderThickness;
}

UIEditorPanelFrameAction HitTestUIEditorPanelFrameAction(
    const UIEditorPanelFrameLayout& layout,
    const UIEditorPanelFrameState& state,
    const UIPoint& point) {
    if (layout.showPinButton &&
        IsUIEditorPanelFramePinButtonVisible(state) &&
        IsUIEditorPanelFramePointInside(layout.pinButtonRect, point)) {
        return UIEditorPanelFrameAction::Pin;
    }

    if (layout.showCloseButton &&
        IsUIEditorPanelFrameCloseButtonVisible(state) &&
        IsUIEditorPanelFramePointInside(layout.closeButtonRect, point)) {
        return UIEditorPanelFrameAction::Close;
    }

    return UIEditorPanelFrameAction::None;
}

UIEditorPanelFrameHitTarget HitTestUIEditorPanelFrame(
    const UIEditorPanelFrameLayout& layout,
    const UIEditorPanelFrameState& state,
    const UIPoint& point) {
    if (!IsUIEditorPanelFramePointInside(layout.frameRect, point)) {
        return UIEditorPanelFrameHitTarget::None;
    }

    switch (HitTestUIEditorPanelFrameAction(layout, state, point)) {
    case UIEditorPanelFrameAction::Pin:
        return UIEditorPanelFrameHitTarget::PinButton;
    case UIEditorPanelFrameAction::Close:
        return UIEditorPanelFrameHitTarget::CloseButton;
    default:
        break;
    }

    if (IsUIEditorPanelFramePointInside(layout.headerRect, point)) {
        return UIEditorPanelFrameHitTarget::Header;
    }

    if (layout.hasFooter && IsUIEditorPanelFramePointInside(layout.footerRect, point)) {
        return UIEditorPanelFrameHitTarget::Footer;
    }

    if (IsUIEditorPanelFramePointInside(layout.bodyRect, point)) {
        return UIEditorPanelFrameHitTarget::Body;
    }

    return UIEditorPanelFrameHitTarget::Body;
}

void AppendUIEditorPanelFrameBackground(
    UIDrawList& drawList,
    const UIEditorPanelFrameLayout& layout,
    const UIEditorPanelFrameState& state,
    const UIEditorPanelFramePalette& palette,
    const UIEditorPanelFrameMetrics& metrics) {
    drawList.AddFilledRect(layout.frameRect, palette.surfaceColor, metrics.cornerRounding);
    drawList.AddRectOutline(
        layout.frameRect,
        ResolveUIEditorPanelFrameBorderColor(state, palette),
        ResolveUIEditorPanelFrameBorderThickness(state, metrics),
        metrics.cornerRounding);
    drawList.AddFilledRect(layout.headerRect, palette.headerColor, metrics.cornerRounding);
    if (layout.hasFooter) {
        drawList.AddFilledRect(layout.footerRect, palette.footerColor, metrics.cornerRounding);
    }
}

void AppendUIEditorPanelFrameForeground(
    UIDrawList& drawList,
    const UIEditorPanelFrameLayout& layout,
    const UIEditorPanelFrameState& state,
    const UIEditorPanelFrameText& text,
    const UIEditorPanelFramePalette& palette,
    const UIEditorPanelFrameMetrics& metrics) {
    if (!text.title.empty()) {
        drawList.AddText(
            UIPoint(layout.frameRect.x + metrics.titleInsetX, layout.headerRect.y + metrics.titleInsetY),
            std::string(text.title),
            palette.textPrimary,
            16.0f);
    }

    if (!text.subtitle.empty()) {
        drawList.AddText(
            UIPoint(layout.frameRect.x + metrics.titleInsetX, layout.headerRect.y + metrics.subtitleInsetY),
            std::string(text.subtitle),
            palette.textSecondary,
            12.0f);
    }

    if (layout.hasFooter && !text.footer.empty()) {
        drawList.AddText(
            UIPoint(layout.footerRect.x + metrics.footerInsetX, layout.footerRect.y + metrics.footerInsetY),
            std::string(text.footer),
            palette.textMuted,
            11.0f);
    }

    if (layout.showPinButton) {
        AppendActionButton(
            drawList,
            layout.pinButtonRect,
            "P",
            state.pinned,
            state.pinHovered,
            palette);
    }

    if (layout.showCloseButton) {
        AppendActionButton(
            drawList,
            layout.closeButtonRect,
            "X",
            false,
            state.closeHovered,
            palette);
    }
}

void AppendUIEditorPanelFrame(
    UIDrawList& drawList,
    const UIRect& frameRect,
    const UIEditorPanelFrameState& state,
    const UIEditorPanelFrameText& text,
    const UIEditorPanelFramePalette& palette,
    const UIEditorPanelFrameMetrics& metrics) {
    const UIEditorPanelFrameLayout layout =
        BuildUIEditorPanelFrameLayout(frameRect, state, metrics);
    AppendUIEditorPanelFrameBackground(drawList, layout, state, palette, metrics);
    AppendUIEditorPanelFrameForeground(drawList, layout, state, text, palette, metrics);
}

} // namespace XCEngine::UI::Editor::Widgets