#include "BorderlessWindowChrome.h"

#include <algorithm>
#include <cmath>

namespace XCEngine::UI::Editor::Host {

namespace {

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

constexpr UIColor kTransparentColor(0.0f, 0.0f, 0.0f, 0.0f);

float ResolveGlyphBoxSize(const UIRect& rect, float ratio, float minSize) {
    return (std::max)(minSize, static_cast<float>(std::round(rect.height * ratio)));
}

void AppendMinimizeGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float halfWidth = ResolveGlyphBoxSize(rect, 0.38f, 10.0f) * 0.5f;
    const float y = centerY;
    drawList.AddLine(
        UIPoint(centerX - halfWidth, y),
        UIPoint(centerX + halfWidth, y),
        color,
        thickness);
}

void AppendMaximizeGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float boxSize = ResolveGlyphBoxSize(rect, 0.32f, 9.0f);
    const float halfExtent = boxSize * 0.5f;
    const float left = centerX - halfExtent;
    const float top = centerY - halfExtent;
    const float right = left + boxSize;
    const float bottom = top + boxSize;
    drawList.AddLine(UIPoint(left, top), UIPoint(right, top), color, thickness);
    drawList.AddLine(UIPoint(left, top), UIPoint(left, bottom), color, thickness);
    drawList.AddLine(UIPoint(right, top), UIPoint(right, bottom), color, thickness);
    drawList.AddLine(UIPoint(left, bottom), UIPoint(right, bottom), color, thickness);
}

void AppendRestoreGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float boxSize = ResolveGlyphBoxSize(rect, 0.29f, 8.0f);
    const float halfExtent = boxSize * 0.5f;
    const float offset = 1.0f;

    const float backLeft = centerX - halfExtent + offset;
    const float backTop = centerY - halfExtent - offset;
    const float backRight = backLeft + boxSize;
    const float backBottom = backTop + boxSize;

    const float frontLeft = centerX - halfExtent - offset;
    const float frontTop = centerY - halfExtent + offset;
    const float frontRight = frontLeft + boxSize;
    const float frontBottom = frontTop + boxSize;

    drawList.AddLine(UIPoint(backLeft, backTop), UIPoint(backRight, backTop), color, thickness);
    drawList.AddLine(UIPoint(backLeft, backTop), UIPoint(backLeft, frontTop), color, thickness);
    drawList.AddLine(UIPoint(backRight, backTop), UIPoint(backRight, backBottom), color, thickness);
    drawList.AddLine(UIPoint(frontRight, backBottom), UIPoint(backRight, backBottom), color, thickness);

    drawList.AddLine(UIPoint(frontLeft, frontTop), UIPoint(frontRight, frontTop), color, thickness);
    drawList.AddLine(UIPoint(frontLeft, frontTop), UIPoint(frontLeft, frontBottom), color, thickness);
    drawList.AddLine(UIPoint(frontRight, frontTop), UIPoint(frontRight, frontBottom), color, thickness);
    drawList.AddLine(UIPoint(frontLeft, frontBottom), UIPoint(frontRight, frontBottom), color, thickness);
}

void AppendCloseGlyph(
    UIDrawList& drawList,
    const UIRect& rect,
    const UIColor& color,
    float thickness) {
    const float centerX = rect.x + rect.width * 0.5f;
    const float centerY = rect.y + rect.height * 0.5f;
    const float halfWidth = ResolveGlyphBoxSize(rect, 0.29f, 8.0f) * 0.5f;
    const float halfHeight = halfWidth;
    drawList.AddLine(
        UIPoint(centerX - halfWidth, centerY - halfHeight),
        UIPoint(centerX + halfWidth, centerY + halfHeight),
        color,
        thickness);
    drawList.AddLine(
        UIPoint(centerX + halfWidth, centerY - halfHeight),
        UIPoint(centerX - halfWidth, centerY + halfHeight),
        color,
        thickness);
}

UIColor ResolveButtonFillColor(
    BorderlessWindowChromeHitTarget target,
    const BorderlessWindowChromeState& state,
    const BorderlessWindowChromePalette& palette) {
    const bool hovered = state.hoveredTarget == target;
    const bool pressed = state.pressedTarget == target;
    if (target == BorderlessWindowChromeHitTarget::CloseButton) {
        if (pressed) {
            return palette.closeButtonPressedColor;
        }
        if (hovered) {
            return palette.closeButtonHoverColor;
        }
        return kTransparentColor;
    }

    if (pressed) {
        return palette.buttonPressedColor;
    }
    if (hovered) {
        return palette.buttonHoverColor;
    }
    return kTransparentColor;
}

UIColor ResolveIconColor(
    BorderlessWindowChromeHitTarget target,
    const BorderlessWindowChromeState& state,
    const BorderlessWindowChromePalette& palette) {
    if (target == BorderlessWindowChromeHitTarget::CloseButton &&
        (state.hoveredTarget == target || state.pressedTarget == target)) {
        return palette.closeIconHoverColor;
    }

    return palette.iconColor;
}

} // namespace

void AppendBorderlessWindowChrome(
    UIDrawList& drawList,
    const BorderlessWindowChromeLayout& layout,
    const BorderlessWindowChromeState& state,
    bool maximized,
    const BorderlessWindowChromePalette& palette,
    const BorderlessWindowChromeMetrics& metrics) {
    const struct ButtonEntry {
        BorderlessWindowChromeHitTarget target;
        UIRect rect;
    } buttons[] = {
        { BorderlessWindowChromeHitTarget::MinimizeButton, layout.minimizeButtonRect },
        { BorderlessWindowChromeHitTarget::MaximizeRestoreButton, layout.maximizeRestoreButtonRect },
        { BorderlessWindowChromeHitTarget::CloseButton, layout.closeButtonRect }
    };

    for (const ButtonEntry& button : buttons) {
        const UIColor fill = ResolveButtonFillColor(button.target, state, palette);
        if (fill.a > 0.0f) {
            drawList.AddFilledRect(button.rect, fill);
        }

        const UIColor iconColor = ResolveIconColor(button.target, state, palette);
        switch (button.target) {
        case BorderlessWindowChromeHitTarget::MinimizeButton:
            AppendMinimizeGlyph(drawList, button.rect, iconColor, metrics.iconThickness);
            break;
        case BorderlessWindowChromeHitTarget::MaximizeRestoreButton:
            if (maximized) {
                AppendRestoreGlyph(drawList, button.rect, iconColor, metrics.iconThickness);
            } else {
                AppendMaximizeGlyph(drawList, button.rect, iconColor, metrics.iconThickness);
            }
            break;
        case BorderlessWindowChromeHitTarget::CloseButton:
            AppendCloseGlyph(drawList, button.rect, iconColor, metrics.iconThickness);
            break;
        case BorderlessWindowChromeHitTarget::DragRegion:
        case BorderlessWindowChromeHitTarget::None:
        default:
            break;
        }
    }
}

} // namespace XCEngine::UI::Editor::Host