#include <XCEditor/Fields/UIEditorAssetField.h>
#include <XCEditor/Widgets/UIEditorFieldRowLayout.h>
#include <XCEditor/Widgets/UIEditorTextLayout.h>

#include <algorithm>
#include <cctype>
#include <string_view>

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

namespace {

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

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

float EstimateTextWidth(std::string_view text, float fontSize) {
    return static_cast<float>(text.size()) * fontSize * 0.58f;
}

bool ShowsPickerButton(const UIEditorAssetFieldSpec& spec) {
    return spec.showPickerButton;
}

bool ShowsClearButton(const UIEditorAssetFieldSpec& spec) {
    return spec.allowClear && HasUIEditorAssetFieldValue(spec);
}

bool ShowsStatusBadge(const UIEditorAssetFieldSpec& spec) {
    return spec.showStatusBadge && !spec.statusText.empty();
}

::XCEngine::UI::UIColor ResolveRowFillColor(
    const UIEditorAssetFieldState& state,
    const UIEditorAssetFieldPalette& palette) {
    if (state.activeTarget != UIEditorAssetFieldHitTargetKind::None) {
        return palette.rowActiveColor;
    }
    if (state.hoveredTarget != UIEditorAssetFieldHitTargetKind::None) {
        return palette.rowHoverColor;
    }
    return palette.surfaceColor;
}

::XCEngine::UI::UIColor ResolveValueFillColor(
    const UIEditorAssetFieldSpec& spec,
    const UIEditorAssetFieldState& state,
    const UIEditorAssetFieldPalette& palette) {
    if (spec.readOnly) {
        return palette.readOnlyColor;
    }
    if (state.activeTarget == UIEditorAssetFieldHitTargetKind::ValueBox ||
        state.activeTarget == UIEditorAssetFieldHitTargetKind::PickerButton ||
        state.activeTarget == UIEditorAssetFieldHitTargetKind::ClearButton) {
        return palette.valueBoxActiveColor;
    }
    if (state.hoveredTarget == UIEditorAssetFieldHitTargetKind::ValueBox ||
        state.hoveredTarget == UIEditorAssetFieldHitTargetKind::PickerButton ||
        state.hoveredTarget == UIEditorAssetFieldHitTargetKind::ClearButton) {
        return palette.valueBoxHoverColor;
    }
    return palette.valueBoxColor;
}

::XCEngine::UI::UIColor ResolveActionFillColor(
    UIEditorAssetFieldHitTargetKind targetKind,
    const UIEditorAssetFieldState& state,
    const UIEditorAssetFieldPalette& palette) {
    if (state.activeTarget == targetKind) {
        return palette.actionButtonActiveColor;
    }
    if (state.hoveredTarget == targetKind) {
        return palette.actionButtonHoverColor;
    }
    return palette.actionButtonColor;
}

} // namespace

bool HasUIEditorAssetFieldValue(const UIEditorAssetFieldSpec& spec) {
    return !spec.assetId.empty() || !spec.displayName.empty();
}

std::string ResolveUIEditorAssetFieldValueText(const UIEditorAssetFieldSpec& spec) {
    if (!spec.displayName.empty()) {
        return spec.displayName;
    }

    if (!spec.assetId.empty()) {
        return spec.assetId;
    }

    return spec.emptyText.empty() ? std::string("None") : spec.emptyText;
}

std::string ResolveUIEditorAssetFieldPreviewGlyph(const UIEditorAssetFieldSpec& spec) {
    const std::string source =
        !spec.statusText.empty() ? spec.statusText : ResolveUIEditorAssetFieldValueText(spec);
    for (char character : source) {
        if (std::isalnum(static_cast<unsigned char>(character)) != 0) {
            return std::string(
                1u,
                static_cast<char>(std::toupper(static_cast<unsigned char>(character))));
        }
    }

    return "-";
}

bool IsUIEditorAssetFieldPointInside(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;
}

UIEditorAssetFieldLayout BuildUIEditorAssetFieldLayout(
    const UIRect& bounds,
    const UIEditorAssetFieldSpec& spec,
    const UIEditorAssetFieldMetrics& metrics) {
    const UIEditorFieldRowLayout hostLayout = BuildUIEditorFieldRowLayout(
        bounds,
        metrics.valueBoxMinWidth,
        UIEditorFieldRowLayoutMetrics {
            metrics.rowHeight,
            metrics.horizontalPadding,
            metrics.labelControlGap,
            metrics.controlColumnStart,
            metrics.controlTrailingInset,
            metrics.controlInsetY,
        });

    UIEditorAssetFieldLayout layout = {};
    layout.bounds = hostLayout.bounds;
    layout.labelRect = hostLayout.labelRect;
    layout.controlRect = hostLayout.controlRect;
    layout.valueRect = hostLayout.controlRect;

    float trailingX = layout.valueRect.x + layout.valueRect.width;
    if (ShowsPickerButton(spec)) {
        trailingX -= metrics.actionButtonWidth;
        layout.pickerRect = UIRect(
            trailingX,
            layout.valueRect.y,
            metrics.actionButtonWidth,
            layout.valueRect.height);
        trailingX -= metrics.actionButtonGap;
    }

    if (ShowsClearButton(spec)) {
        trailingX -= metrics.actionButtonWidth;
        layout.clearRect = UIRect(
            trailingX,
            layout.valueRect.y,
            metrics.actionButtonWidth,
            layout.valueRect.height);
        trailingX -= metrics.actionButtonGap;
    }

    const float previewSize =
        (std::min)(metrics.previewSize, ClampNonNegative(layout.valueRect.height - 4.0f));
    layout.previewRect = UIRect(
        layout.valueRect.x + metrics.previewInsetX,
        layout.valueRect.y + ClampNonNegative((layout.valueRect.height - previewSize) * 0.5f),
        previewSize,
        previewSize);

    const float contentLeft = layout.previewRect.x + layout.previewRect.width + metrics.previewGap;
    if (ShowsStatusBadge(spec)) {
        const float estimatedBadgeWidth =
            EstimateTextWidth(spec.statusText, metrics.statusBadgeFontSize) +
            metrics.statusBadgePaddingX * 2.0f;
        const float badgeWidth = (std::min)(
            (std::max)(metrics.statusBadgeMinWidth, estimatedBadgeWidth),
            ClampNonNegative((trailingX - contentLeft) * 0.45f));
        if (badgeWidth > 20.0f) {
            trailingX -= badgeWidth;
            layout.statusBadgeRect = UIRect(
                trailingX,
                layout.valueRect.y + ClampNonNegative((layout.valueRect.height - metrics.statusBadgeHeight) * 0.5f),
                badgeWidth,
                (std::min)(metrics.statusBadgeHeight, layout.valueRect.height));
            trailingX -= metrics.statusBadgeGap;
        }
    }

    layout.textRect = UIRect(
        contentLeft + metrics.valueTextInsetX,
        layout.valueRect.y,
        ClampNonNegative(trailingX - contentLeft - metrics.valueTextInsetX),
        layout.valueRect.height);
    return layout;
}

UIEditorAssetFieldHitTarget HitTestUIEditorAssetField(
    const UIEditorAssetFieldLayout& layout,
    const UIPoint& point) {
    if (layout.clearRect.width > 0.0f &&
        IsUIEditorAssetFieldPointInside(layout.clearRect, point)) {
        return { UIEditorAssetFieldHitTargetKind::ClearButton };
    }
    if (layout.pickerRect.width > 0.0f &&
        IsUIEditorAssetFieldPointInside(layout.pickerRect, point)) {
        return { UIEditorAssetFieldHitTargetKind::PickerButton };
    }
    if (IsUIEditorAssetFieldPointInside(layout.valueRect, point)) {
        return { UIEditorAssetFieldHitTargetKind::ValueBox };
    }
    if (IsUIEditorAssetFieldPointInside(layout.bounds, point)) {
        return { UIEditorAssetFieldHitTargetKind::Row };
    }
    return {};
}

void AppendUIEditorAssetFieldBackground(
    UIDrawList& drawList,
    const UIEditorAssetFieldLayout& layout,
    const UIEditorAssetFieldSpec& spec,
    const UIEditorAssetFieldState& state,
    const UIEditorAssetFieldPalette& palette,
    const UIEditorAssetFieldMetrics& metrics) {
    const auto rowFillColor = ResolveRowFillColor(state, palette);
    if (rowFillColor.a > 0.0f) {
        drawList.AddFilledRect(layout.bounds, rowFillColor, metrics.cornerRounding);
    }

    const auto rowBorderColor = state.focused ? palette.focusedBorderColor : palette.borderColor;
    if (rowBorderColor.a > 0.0f) {
        drawList.AddRectOutline(
            layout.bounds,
            rowBorderColor,
            state.focused ? metrics.focusedBorderThickness : metrics.borderThickness,
            metrics.cornerRounding);
    }

    drawList.AddFilledRect(
        layout.valueRect,
        ResolveValueFillColor(spec, state, palette),
        metrics.valueBoxRounding);
    drawList.AddRectOutline(
        layout.valueRect,
        state.focused ? palette.controlFocusedBorderColor : palette.controlBorderColor,
        state.focused ? metrics.focusedBorderThickness : metrics.borderThickness,
        metrics.valueBoxRounding);

    if (HasUIEditorAssetFieldValue(spec)) {
        drawList.AddFilledRectLinearGradient(
            layout.previewRect,
            palette.previewBaseColor,
            spec.tint,
            ::XCEngine::UI::UILinearGradientDirection::Vertical,
            metrics.previewRounding);
    } else {
        drawList.AddFilledRect(layout.previewRect, palette.previewEmptyColor, metrics.previewRounding);
    }
    drawList.AddRectOutline(
        layout.previewRect,
        palette.previewBorderColor,
        metrics.borderThickness,
        metrics.previewRounding);

    if (layout.statusBadgeRect.width > 0.0f && layout.statusBadgeRect.height > 0.0f) {
        drawList.AddFilledRect(layout.statusBadgeRect, palette.statusBadgeColor, metrics.badgeRounding);
        drawList.AddRectOutline(
            layout.statusBadgeRect,
            palette.statusBadgeBorderColor,
            metrics.borderThickness,
            metrics.badgeRounding);
    }

    if (layout.pickerRect.width > 0.0f) {
        const auto fill =
            ResolveActionFillColor(UIEditorAssetFieldHitTargetKind::PickerButton, state, palette);
        drawList.AddFilledRect(layout.pickerRect, fill, metrics.valueBoxRounding);
        drawList.AddLine(
            UIPoint(layout.pickerRect.x, layout.pickerRect.y + 1.0f),
            UIPoint(layout.pickerRect.x, layout.pickerRect.y + layout.pickerRect.height - 1.0f),
            palette.separatorColor,
            1.0f);
    }

    if (layout.clearRect.width > 0.0f) {
        const auto fill =
            ResolveActionFillColor(UIEditorAssetFieldHitTargetKind::ClearButton, state, palette);
        drawList.AddFilledRect(layout.clearRect, fill, metrics.valueBoxRounding);
        drawList.AddLine(
            UIPoint(layout.clearRect.x, layout.clearRect.y + 1.0f),
            UIPoint(layout.clearRect.x, layout.clearRect.y + layout.clearRect.height - 1.0f),
            palette.separatorColor,
            1.0f);
    }
}

void AppendUIEditorAssetFieldForeground(
    UIDrawList& drawList,
    const UIEditorAssetFieldLayout& layout,
    const UIEditorAssetFieldSpec& spec,
    const UIEditorAssetFieldState&,
    const UIEditorAssetFieldPalette& palette,
    const UIEditorAssetFieldMetrics& metrics) {
    drawList.PushClipRect(ResolveUIEditorTextClipRect(layout.labelRect, metrics.labelFontSize));
    drawList.AddText(
        UIPoint(
            layout.labelRect.x,
            ResolveUIEditorTextTop(layout.labelRect, metrics.labelFontSize, metrics.labelTextInsetY)),
        spec.label,
        palette.labelColor,
        metrics.labelFontSize);
    drawList.PopClipRect();

    drawList.PushClipRect(ResolveUIEditorTextClipRect(layout.previewRect, metrics.previewGlyphFontSize));
    drawList.AddText(
        UIPoint(
            layout.previewRect.x +
                ClampNonNegative((layout.previewRect.width - metrics.previewGlyphFontSize) * 0.5f),
            ResolveUIEditorTextTop(layout.previewRect, metrics.previewGlyphFontSize, -1.0f)),
        ResolveUIEditorAssetFieldPreviewGlyph(spec),
        palette.previewGlyphColor,
        metrics.previewGlyphFontSize);
    drawList.PopClipRect();

    drawList.PushClipRect(ResolveUIEditorTextClipRect(layout.textRect, metrics.valueFontSize));
    drawList.AddText(
        UIPoint(
            layout.textRect.x,
            ResolveUIEditorTextTop(layout.textRect, metrics.valueFontSize, metrics.valueTextInsetY)),
        ResolveUIEditorAssetFieldValueText(spec),
        HasUIEditorAssetFieldValue(spec) ? palette.valueColor : palette.emptyValueColor,
        metrics.valueFontSize);
    drawList.PopClipRect();

    if (layout.statusBadgeRect.width > 0.0f && layout.statusBadgeRect.height > 0.0f) {
        const UIRect badgeTextRect(
            layout.statusBadgeRect.x + metrics.statusBadgePaddingX,
            layout.statusBadgeRect.y,
            ClampNonNegative(layout.statusBadgeRect.width - metrics.statusBadgePaddingX * 2.0f),
            layout.statusBadgeRect.height);
        drawList.PushClipRect(ResolveUIEditorTextClipRect(badgeTextRect, metrics.statusBadgeFontSize));
        drawList.AddText(
            UIPoint(
                badgeTextRect.x,
                ResolveUIEditorTextTop(badgeTextRect, metrics.statusBadgeFontSize, -1.0f)),
            spec.statusText,
            palette.statusBadgeTextColor,
            metrics.statusBadgeFontSize);
        drawList.PopClipRect();
    }

    if (layout.pickerRect.width > 0.0f) {
        drawList.AddText(
            UIPoint(
                layout.pickerRect.x +
                    ClampNonNegative((layout.pickerRect.width - metrics.actionGlyphFontSize) * 0.5f),
                ResolveUIEditorTextTop(
                    layout.pickerRect,
                    metrics.actionGlyphFontSize,
                    metrics.actionGlyphInsetY)),
            "o",
            palette.pickerGlyphColor,
            metrics.actionGlyphFontSize);
    }

    if (layout.clearRect.width > 0.0f) {
        drawList.AddText(
            UIPoint(
                layout.clearRect.x +
                    ClampNonNegative((layout.clearRect.width - metrics.actionGlyphFontSize) * 0.5f),
                ResolveUIEditorTextTop(
                    layout.clearRect,
                    metrics.actionGlyphFontSize,
                    metrics.actionGlyphInsetY)),
            "X",
            palette.clearGlyphColor,
            metrics.actionGlyphFontSize);
    }
}

void AppendUIEditorAssetField(
    UIDrawList& drawList,
    const UIRect& bounds,
    const UIEditorAssetFieldSpec& spec,
    const UIEditorAssetFieldState& state,
    const UIEditorAssetFieldPalette& palette,
    const UIEditorAssetFieldMetrics& metrics) {
    const UIEditorAssetFieldLayout layout = BuildUIEditorAssetFieldLayout(bounds, spec, metrics);
    AppendUIEditorAssetFieldBackground(drawList, layout, spec, state, palette, metrics);
    AppendUIEditorAssetFieldForeground(drawList, layout, spec, state, palette, metrics);
}

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