#include "ColorPickerPopup.hpp"

#include <algorithm>
#include <cmath>
#include <cstdlib>

#include "Utf8Util.hpp"

namespace jdi
{

	namespace
	{
		const float kPanelWidth = 324.0f;		/**< 面板宽度（逻辑像素）。 */
		const float kPadH = 12.0f;				/**< 面板左右内边距。 */
		const float kPadV = 10.0f;				/**< 面板上下内边距。 */
		const float kTitleHeight = 20.0f;		/**< 标题行高度。 */
		const float kTitleGap = 8.0f;			/**< 标题与内容区间距。 */
		const float kRowHeight = 26.0f;			/**< 单个滑块行高度。 */
		const float kRowGap = 2.0f;				/**< 滑块行间距。 */
		const float kPreviewGap = 10.0f;		/**< 滑块区与预览区间距。 */
		const float kPreviewHeight = 24.0f;		/**< 预览行高度。 */
		const float kLabelWidth = 16.0f;		/**< 通道标签宽度。 */
		const float kLabelGap = 6.0f;			/**< 标签与滑块间距。 */
		const float kValueWidth = 40.0f;		/**< 数值文本宽度。 */
		const float kTrackHeight = 8.0f;		/**< 滑块轨道高度。 */
		const float kCorner = 6.0f;				/**< 面板圆角半径。 */
		/** 色域方块 / 色相条 / 预览色块 / 色号框共用同一圆角（视觉上统一）。 */
		const float kSwatchCorner = 3.0f;
		const float kGamutSize = 112.0f;		/**< 色域方块边长。 */
		const float kHueWidth = 14.0f;			/**< 色相条宽度。 */
		const float kGamutGap = 10.0f;			/**< 色域方块与色相条间距。 */
		const float kColumnGap = 12.0f;			/**< 色相条与滑块列间距。 */
		const float kSwatchWidth = 52.0f;		/**< 预览色块宽度。 */
		const float kSwatchHexGap = 8.0f;		/**< 预览色块与色号间距。 */
		const float kGamutBorder = 1.0f;		/**< 色域方块/色相条描边宽度。 */

		/** @brief 通道显示名称。 */
		const wchar_t* kChannelNames[3] = {L"R", L"G", L"B"};

		/** @brief 通道滑块填充色。 */
		const std::uint32_t kChannelColors[3] = {0xFFDC322Fu, 0xFF859900u, 0xFF268BD2u};

		/**
		 * @brief 把数值限制到 0-1。
		 * @param [IN] value 输入值。
		 * @return 限制后的值。
		 */
		double Clamp01(double value)
		{
			if (value < 0.0)
			{
				return 0.0;
			}
			if (value > 1.0)
			{
				return 1.0;
			}
			return value;
		}

		/**
		 * @brief HSV 颜色（色相/饱和度/明度，均为 0-1）。
		 */
		struct Hsv
		{
			double h = 0.0;		/**< 色相。 */
			double s = 0.0;		/**< 饱和度。 */
			double v = 0.0;		/**< 明度。 */
		};

		/**
		 * @brief RGB（0-1 分量）转 HSV。
		 * @param [IN] rgb RGB 分量。
		 * @return HSV 值（灰色时色相为 0）。
		 */
		Hsv ToHsv(const std::array<double, 3>& rgb)
		{
			const double maximum = std::max(rgb[0], std::max(rgb[1], rgb[2]));
			const double minimum = std::min(rgb[0], std::min(rgb[1], rgb[2]));
			const double delta = maximum - minimum;

			Hsv hsv;
			hsv.v = maximum;
			hsv.s = (maximum > 1.0e-9) ? (delta / maximum) : 0.0;
			if (delta <= 1.0e-9)
			{
				hsv.h = 0.0;
				return hsv;
			}

			double hue = 0.0;
			if (maximum == rgb[0])
			{
				hue = (rgb[1] - rgb[2]) / delta;
			}
			else if (maximum == rgb[1])
			{
				hue = 2.0 + (rgb[2] - rgb[0]) / delta;
			}
			else
			{
				hue = 4.0 + (rgb[0] - rgb[1]) / delta;
			}
			hue /= 6.0;
			if (hue < 0.0)
			{
				hue += 1.0;
			}
			hsv.h = hue;
			return hsv;
		}

		/**
		 * @brief HSV 转 RGB（0-1 分量）。
		 * @param [IN] h 色相（0-1，自动取模）。
		 * @param [IN] s 饱和度（0-1）。
		 * @param [IN] v 明度（0-1）。
		 * @return RGB 分量。
		 */
		std::array<double, 3> FromHsv(double h, double s, double v)
		{
			h = h - std::floor(h);
			s = Clamp01(s);
			v = Clamp01(v);
			if (s <= 1.0e-9)
			{
				return {v, v, v};
			}

			const double sector = h * 6.0;
			const int index = static_cast<int>(std::floor(sector)) % 6;
			const double fraction = sector - std::floor(sector);
			const double p = v * (1.0 - s);
			const double q = v * (1.0 - s * fraction);
			const double t = v * (1.0 - s * (1.0 - fraction));
			switch (index)
			{
			case 0:
				return {v, t, p};
			case 1:
				return {q, v, p};
			case 2:
				return {p, v, t};
			case 3:
				return {p, q, v};
			case 4:
				return {t, p, v};
			default:
				return {v, p, q};
			}
		}

		/**
		 * @brief 绘制水平滑块（与样式区共用同一实现，保证行为一致）。
		 * @param [IN,OUT] g 绘图上下文。
		 * @param [IN] track 轨道矩形。
		 * @param [IN] ratio 当前值比例（0-1）。
		 * @param [IN] fillColor 已填充部分颜色。
		 * @param [IN] hovered 是否处于悬停或拖拽状态。
		 * @param [IN] scale 缩放比例。
		 */
		void DrawChannelSlider(gd::Graphics& g, const gd::RectF& track, double ratio, std::uint32_t fillColor,
		                       bool hovered, float scale)
		{
			UiDrawSlider(g, track, ratio, fillColor, hovered, scale);
		}

		/**
		 * @brief 将 0-1 分量换算为 0-255 整数。
		 * @param [IN] value 分量值。
		 * @return 整数分量。
		 */
		unsigned int ToByte(double value)
		{
			const double scaled = value * 255.0 + 0.5;
			if (scaled < 0.0)
			{
				return 0u;
			}
			if (scaled > 255.0)
			{
				return 255u;
			}
			return static_cast<unsigned int>(scaled);
		}
	}

	ColorPickerPopup::ColorPickerPopup() = default;

	void ColorPickerPopup::Setup(const UiFonts* fonts, const Theme* theme)
	{
		m_fonts = fonts;
		m_theme = theme;
	}

	void ColorPickerPopup::SetScale(float scale)
	{
		m_scale = (scale > 0.1f) ? scale : 1.0f;
	}

	std::uint32_t ColorPickerPopup::CurrentColor() const
	{
		const unsigned int r = ToByte(m_channels[0]);
		const unsigned int g = ToByte(m_channels[1]);
		const unsigned int b = ToByte(m_channels[2]);
		return 0xFF000000u | (r << 16) | (g << 8) | b;
	}

	bool ColorPickerPopup::TakeChanged(std::uint32_t& color)
	{
		if (!m_changed)
		{
			return false;
		}
		m_changed = false;
		color = CurrentColor();
		return true;
	}

	void ColorPickerPopup::BuildLayout(const gd::RectF& bounds, const gd::RectF& anchor)
	{
		// 布局：左侧一列放"色域方块 + 色相条"，右侧一列放 R/G/B 三行
		//（每行 = 通道标签 + 滑块 + 数值），两列下方再放"预览色块 + 色号"一行。
		// 所有控件都从面板内边距起算，因此不会出现越界。
		const float width = kPanelWidth * m_scale;
		const float height = (kPadV * 2.0f + kTitleHeight + kTitleGap + kGamutSize + kPreviewGap +
		                      kPreviewHeight) *
		                     m_scale;

		const float gap = 4.0f * m_scale;

		// 纵向：优先紧贴触发控件下方展开；空间不足时改到其上方，避免遮挡触发控件本身。
		float top = anchor.Y + anchor.Height + gap;
		if (top + height > bounds.Y + bounds.Height)
		{
			top = anchor.Y - height - gap;
		}
		top = std::max(bounds.Y + 2.0f, std::min(top, bounds.Y + bounds.Height - height - 2.0f));

		// 横向：与触发控件左对齐，越界时再收敛。
		float left = anchor.X;
		if (left + width > bounds.X + bounds.Width)
		{
			left = anchor.X + anchor.Width - width;
		}
		left = std::max(bounds.X + 2.0f, std::min(left, bounds.X + bounds.Width - width - 2.0f));

		m_rect = gd::RectF(left, top, width, height);

		m_titleRect = gd::RectF(left + kPadH * m_scale, top + kPadV * m_scale,
		                        width - kPadH * 2.0f * m_scale, kTitleHeight * m_scale);

		const float contentTop = m_titleRect.Y + m_titleRect.Height + kTitleGap * m_scale;
		const float contentLeft = left + kPadH * m_scale;
		const float contentRight = left + width - kPadH * m_scale;

		// 左列：色域方块（横轴饱和度、纵轴明度）+ 色相条。
		m_gamutRect = gd::RectF(contentLeft, contentTop, kGamutSize * m_scale, kGamutSize * m_scale);
		m_hueRect = gd::RectF(m_gamutRect.X + m_gamutRect.Width + kGamutGap * m_scale, contentTop,
		                      kHueWidth * m_scale, kGamutSize * m_scale);

		// 右列：R/G/B 三行。整列在方块高度内纵向居中，与左侧方块视觉平衡。
		const float leftColumnWidth =
		    (kGamutSize + kGamutGap + kHueWidth) * m_scale;
		const float columnLeft = m_gamutRect.X + leftColumnWidth + kColumnGap * m_scale;
		const float columnWidth = std::max(60.0f * m_scale, contentRight - columnLeft);
		const float rowsHeight = (kRowHeight * 3.0f + kRowGap * 2.0f) * m_scale;
		const float firstRowTop =
		    contentTop + std::max(0.0f, (kGamutSize * m_scale - rowsHeight) * 0.5f);

		const float trackLeft = columnLeft + (kLabelWidth + kLabelGap) * m_scale;
		const float trackWidth =
		    std::max(24.0f, columnWidth - (kLabelWidth + kLabelGap + kValueWidth + 6.0f) * m_scale);

		for (int index = 0; index < 3; ++index)
		{
			const float rowTop = firstRowTop + static_cast<float>(index) * (kRowHeight + kRowGap) * m_scale;
			m_tracks[static_cast<std::size_t>(index)] =
			    gd::RectF(trackLeft, rowTop + (kRowHeight * m_scale - kTrackHeight * m_scale) * 0.5f,
			              trackWidth, kTrackHeight * m_scale);
			m_values[static_cast<std::size_t>(index)] =
			    gd::RectF(trackLeft + trackWidth + 6.0f * m_scale, rowTop, kValueWidth * m_scale,
			              kRowHeight * m_scale);
		}

		// 下行：预览色块 + 色号，与上方的"方块 + 色相条"同宽。
		const float previewTop = contentTop + (kGamutSize + kPreviewGap) * m_scale;
		m_previewRect =
		    gd::RectF(contentLeft, previewTop, kSwatchWidth * m_scale, kPreviewHeight * m_scale);
		m_hexRect = gd::RectF(m_previewRect.X + m_previewRect.Width + kSwatchHexGap * m_scale,
		                      previewTop,
		                      std::max(40.0f * m_scale, leftColumnWidth - (kSwatchWidth + kSwatchHexGap) * m_scale),
		                      kPreviewHeight * m_scale);
	}

	void ColorPickerPopup::Open(const gd::RectF& bounds, const gd::RectF& anchor, std::uint32_t color)
	{
		m_channels[0] = static_cast<double>((color >> 16) & 0xFFu) / 255.0;
		m_channels[1] = static_cast<double>((color >> 8) & 0xFFu) / 255.0;
		m_channels[2] = static_cast<double>(color & 0xFFu) / 255.0;

		m_open = true;
		m_changed = false;
		m_draggingSlider = -1;
		m_hoverSlider = -1;
		m_drag = DragTarget::NONE;
		// 记住初始色相与选点位置：之后即使把明度拖到 0（黑色）色相/饱和度也不会丢失。
		RefreshSelectionFromChannels();
		InvalidateGamutCache();

		BuildLayout(bounds, anchor);
	}

	void ColorPickerPopup::Close()
	{
		// 收起前先提交正在编辑的取值，避免用户输入被静默丢弃。
		if (m_editField != EditField::NONE)
		{
			EndEdit(true);
		}
		m_open = false;
		m_draggingSlider = -1;
		m_hoverSlider = -1;
		m_drag = DragTarget::NONE;
		// 释放色域方块缓存（它是 GDI+ 对象，必须在 GdiplusShutdown 之前销毁）。
		// 下次打开时按需重建，代价只有一张小位图的填充。
		m_gamutCache.reset();
		m_gamutCacheSize = 0;
		m_gamutCacheHue = -1.0;
	}

	double ColorPickerPopup::CurrentHue() const
	{
		// 直接返回保存的色相选择值（不再从 RGB 反推）：
		// 色相 1 与 0 是同一个颜色（红），反推会把它们归一到 0，
		// 表现为"把滑块拖到最下面却弹回最上面"。
		// `RefreshSelectionFromChannels` 会在改色（RGB 滑块 / 色号）后同步这个值。
		return m_hue;
	}

	void ColorPickerPopup::RefreshSelectionFromChannels()
	{
		const Hsv hsv = ToHsv(m_channels);
		// 饱和度足够大时才认色相（灰度时色相无定义，沿用上次取值）。
		if (hsv.s > 1.0e-4)
		{
			m_hue = hsv.h;
		}
		// 饱和度/明度总是可以从 RGB 反推（明度=最大值，饱和度=max>0 ? delta/max : 0）。
		// 注意这是"由 RGB 派生"的路径，只用于外部改色（滑块/色号）后的同步；
		// 直接用色域方块时不会走这里，以免黑色把饱和度重置为 0。
		m_sat = hsv.s;
		m_val = hsv.v;
	}

	void ColorPickerPopup::InvalidateGamutCache()
	{
		m_gamutCacheHue = -1.0;
	}

	bool ColorPickerPopup::EnsureGamutCache()
	{
		const int size = std::max(8, static_cast<int>(std::lround(kGamutSize * m_scale)));
		if (m_gamutCache == nullptr || m_gamutCacheSize != size)
		{
			m_gamutCache.reset(new gd::Bitmap(size, size, PixelFormat32bppRGB));
			m_gamutCacheSize = size;
			m_gamutCacheHue = -1.0;
		}

		const double hue = CurrentHue();
		if (std::fabs(m_gamutCacheHue - hue) < 1.0e-4)
		{
			return true;
		}

		gd::BitmapData data = {};
		const gd::Rect lockRect(0, 0, size, size);
		if (m_gamutCache->LockBits(&lockRect, gd::ImageLockModeWrite, PixelFormat32bppRGB, &data) != gd::Ok)
		{
			return false;
		}
		unsigned char* base = static_cast<unsigned char*>(data.Scan0);
		for (int y = 0; y < size; ++y)
		{
			// 纵轴明度（上 1 → 下 0），横轴饱和度（左 0 → 右 1）——与常见取色器一致。
			const double value = 1.0 - (static_cast<double>(y) + 0.5) / static_cast<double>(size);
			unsigned char* row = (data.Stride >= 0)
			                         ? (base + static_cast<std::ptrdiff_t>(y) * data.Stride)
			                         : (base + static_cast<std::ptrdiff_t>(size - 1 - y) * (-data.Stride));
			for (int x = 0; x < size; ++x)
			{
				const double saturation =
				    (static_cast<double>(x) + 0.5) / static_cast<double>(size);
				const std::array<double, 3> rgb = FromHsv(hue, saturation, value);
				row[x * 4 + 0] = static_cast<unsigned char>(ToByte(rgb[2]));	// B
				row[x * 4 + 1] = static_cast<unsigned char>(ToByte(rgb[1]));	// G
				row[x * 4 + 2] = static_cast<unsigned char>(ToByte(rgb[0]));	// R
				row[x * 4 + 3] = 0xFF;
			}
		}
		m_gamutCache->UnlockBits(&data);
		m_gamutCacheHue = hue;
		return true;
	}

	void ColorPickerPopup::ApplyGamut(float x, float y)
	{
		if (m_gamutRect.Width <= 0.0f || m_gamutRect.Height <= 0.0f)
		{
			return;
		}
		// 越出方块时夹取到最近边界（而不是丢失位置）：鼠标拖到方块之外时选点
		// 会停在对应角落，与鼠标相对方块的方位一致。
		const double saturation = Clamp01((x - m_gamutRect.X) / m_gamutRect.Width);
		const double value = 1.0 - Clamp01((y - m_gamutRect.Y) / m_gamutRect.Height);
		if (std::fabs(saturation - m_sat) < 1.0e-9 && std::fabs(value - m_val) < 1.0e-9)
		{
			return;
		}
		// 先记录选点位置，再推颜色：两者分开保存，明度为 0 时饱和度不会因此丢失。
		m_sat = saturation;
		m_val = value;
		m_channels = FromHsv(CurrentHue(), m_sat, m_val);
		m_changed = true;
	}

	void ColorPickerPopup::ApplyHue(float y)
	{
		if (m_hueRect.Height <= 0.0f)
		{
			return;
		}
		// 越出色相条时同样夹取：拖到下方停在最下面（色相 1），不会因 0/1 等价而弹回顶部。
		const double hue = Clamp01((y - m_hueRect.Y) / m_hueRect.Height);
		if (std::fabs(hue - m_hue) < 1.0e-9)
		{
			return;
		}
		m_hue = hue;
		m_channels = FromHsv(m_hue, m_sat, m_val);
		m_changed = true;
	}

	gd::RectF ColorPickerPopup::EditFieldRect() const
	{
		switch (m_editField)
		{
		case EditField::R:
			return m_values[0];
		case EditField::G:
			return m_values[1];
		case EditField::B:
			return m_values[2];
		case EditField::HEX:
			return m_hexRect;
		case EditField::NONE:
		default:
			return gd::RectF();
		}
	}

	bool ColorPickerPopup::BeginEdit(EditField field)
	{
		if (!m_open || field == EditField::NONE)
		{
			return false;
		}
		if (m_editField == field)
		{
			return false;
		}

		switch (field)
		{
		case EditField::R:
		case EditField::G:
		case EditField::B:
		{
			const int index = static_cast<int>(field) - 1;
			m_edit.Begin(std::to_wstring(ToByte(m_channels[static_cast<std::size_t>(index)])), true,
			             EditFilter::BYTE, 0u);
			break;
		}
		case EditField::HEX:
		{
			const std::uint32_t color = CurrentColor();
			wchar_t buffer[16];
			swprintf(buffer, sizeof(buffer) / sizeof(buffer[0]), L"%02X%02X%02X", (color >> 16) & 0xFFu,
			         (color >> 8) & 0xFFu, color & 0xFFu);
			m_edit.Begin(std::wstring(buffer), true, EditFilter::HEX, 0u);
			break;
		}
		default:
			return false;
		}

		m_draggingSlider = -1;
		m_editField = field;
		return true;
	}

	bool ColorPickerPopup::EndEdit(bool commit)
	{
		if (m_editField == EditField::NONE)
		{
			return false;
		}

		const EditField field = m_editField;
		const std::wstring text = m_edit.Text();
		m_editField = EditField::NONE;
		m_edit.End();

		if (!commit)
		{
			return true;
		}

		const std::wstring trimmed = Trim(text);
		if (field == EditField::HEX)
		{
			// 接受带或不带 '#' 的 6 位十六进制色号。
			std::wstring digits = trimmed;
			if (!digits.empty() && digits.front() == L'#')
			{
				digits.erase(digits.begin());
			}
			if (digits.size() == 6)
			{
				unsigned int value = 0;
				bool valid = true;
				for (const wchar_t c : digits)
				{
					unsigned int digit = 0;
					if (c >= L'0' && c <= L'9')
					{
						digit = static_cast<unsigned int>(c - L'0');
					}
					else if (c >= L'a' && c <= L'f')
					{
						digit = static_cast<unsigned int>(c - L'a') + 10u;
					}
					else if (c >= L'A' && c <= L'F')
					{
						digit = static_cast<unsigned int>(c - L'A') + 10u;
					}
					else
					{
						valid = false;
						break;
					}
					value = (value << 4) | digit;
				}
				if (valid)
				{
					m_channels[0] = static_cast<double>((value >> 16) & 0xFFu) / 255.0;
					m_channels[1] = static_cast<double>((value >> 8) & 0xFFu) / 255.0;
					m_channels[2] = static_cast<double>(value & 0xFFu) / 255.0;
					RefreshSelectionFromChannels();
					m_changed = true;
				}
			}
			return true;
		}

		if (trimmed.empty())
		{
			return true;
		}
		wchar_t* stop = nullptr;
		const double parsed = std::wcstod(trimmed.c_str(), &stop);
		if (stop == trimmed.c_str() || parsed != parsed)
		{
			return true;
		}

		double value = parsed;
		if (value < 0.0)
		{
			value = 0.0;
		}
		if (value > 255.0)
		{
			value = 255.0;
		}

		const int index = static_cast<int>(field) - 1;
		if (index >= 0 && index < 3)
		{
			m_channels[static_cast<std::size_t>(index)] = value / 255.0;
			RefreshSelectionFromChannels();
			m_changed = true;
		}
		return true;
	}

	bool ColorPickerPopup::OnChar(wchar_t character)
	{
		if (m_editField == EditField::NONE)
		{
			return false;
		}

		// 剪贴板与全选快捷键经 WM_CHAR 送达（Ctrl+C/X/V/A 分别对应 3/24/22/1）。
		switch (character)
		{
		case 0x03: // Ctrl+C
			m_edit.CopyToClipboard(m_owner);
			return false;
		case 0x18: // Ctrl+X
			return m_edit.CutToClipboard(m_owner);
		case 0x16: // Ctrl+V
			return m_edit.PasteFromClipboard(m_owner);
		case 0x01: // Ctrl+A
			m_edit.SelectAll();
			return true;
		default:
			break;
		}

		if (character == L'\r' || character == L'\n')
		{
			return EndEdit(true);
		}
		// 退格/删除已由 WM_KEYDOWN 的 OnKeyDown 处理，此处忽略控制字符避免重复删除。
		if (character < 0x20 || character == 0x7F)
		{
			return false;
		}
		return m_edit.Insert(character);
	}

	bool ColorPickerPopup::CollapseEditSelectionToEnd()
	{
		if (m_editField == EditField::NONE)
		{
			return false;
		}
		return m_edit.DeselectToEnd();
	}

	bool ColorPickerPopup::OnEditMouseDown(int x, int y)
	{
		if (m_editField == EditField::NONE)
		{
			return false;
		}
		return UiEditFieldMouseDown(m_fonts->monoSmall, EditFieldRect(), m_edit, m_scale, x, y);
	}

	bool ColorPickerPopup::OnEditMouseMove(int x)
	{
		if (m_editField == EditField::NONE)
		{
			return false;
		}
		return UiEditFieldMouseMove(m_fonts->monoSmall, EditFieldRect(), m_edit, m_scale, x);
	}

	bool ColorPickerPopup::OnEditMouseUp()
	{
		if (!m_edit.Dragging())
		{
			return false;
		}
		m_edit.EndDrag();
		return true;
	}

	bool ColorPickerPopup::ContainsPoint(int x, int y) const
	{
		if (!m_open)
		{
			return false;
		}
		return UiPointInRect(m_rect, static_cast<float>(x), static_cast<float>(y));
	}

	HCURSOR ColorPickerPopup::QueryCursor(int x, int y) const
	{
		if (!m_open)
		{
			return nullptr;
		}

		// 拖拽过程中始终保持对应光标，避免指针移出控件后光标跳变。
		if (m_drag == DragTarget::GAMUT || UiPointInRect(m_gamutRect, static_cast<float>(x),
		                                                 static_cast<float>(y)))
		{
			return LoadCursorW(nullptr, IDC_CROSS);
		}
		if (m_drag == DragTarget::HUE ||
		    UiPointInRect(m_hueRect, static_cast<float>(x), static_cast<float>(y)))
		{
			return LoadCursorW(nullptr, IDC_SIZENS);
		}
		if (m_drag == DragTarget::SLIDER || m_draggingSlider >= 0 || SliderAtPoint(x, y) >= 0)
		{
			return LoadCursorW(nullptr, IDC_SIZEWE);
		}
		return LoadCursorW(nullptr, IDC_ARROW);
	}

	int ColorPickerPopup::SliderAtPoint(int x, int y) const
	{
		if (!m_open)
		{
			return -1;
		}

		const float fx = static_cast<float>(x);
		const float fy = static_cast<float>(y);
		for (int index = 0; index < 3; ++index)
		{
			const gd::RectF& track = m_tracks[static_cast<std::size_t>(index)];
			// 命中范围在纵向适当放宽，便于拖拽。
			const gd::RectF hit(track.X - 4.0f * m_scale, track.Y - 9.0f * m_scale,
			                    track.Width + 8.0f * m_scale, track.Height + 18.0f * m_scale);
			if (UiPointInRect(hit, fx, fy))
			{
				return index;
			}
		}
		return -1;
	}

	void ColorPickerPopup::ApplySlider(int index, float x)
	{
		if (index < 0 || index >= 3)
		{
			return;
		}
		const std::size_t slot = static_cast<std::size_t>(index);
		const double ratio = UiSliderRatioFromX(m_tracks[slot], x);
		if (std::fabs(ratio - m_channels[slot]) < 1.0e-6)
		{
			return;
		}
		m_channels[slot] = ratio;
		RefreshSelectionFromChannels();
		m_changed = true;
	}

	bool ColorPickerPopup::OnMouseMove(int x, int y)
	{
		if (!m_open)
		{
			return false;
		}

		switch (m_drag)
		{
		case DragTarget::GAMUT:
			ApplyGamut(static_cast<float>(x), static_cast<float>(y));
			return true;
		case DragTarget::HUE:
			ApplyHue(static_cast<float>(y));
			return true;
		case DragTarget::SLIDER:
			ApplySlider(m_draggingSlider, static_cast<float>(x));
			return true;
		case DragTarget::NONE:
		default:
			break;
		}

		const int hover = SliderAtPoint(x, y);
		if (hover == m_hoverSlider)
		{
			return false;
		}
		m_hoverSlider = hover;
		return true;
	}

	bool ColorPickerPopup::OnLButtonDown(int x, int y)
	{
		if (!m_open)
		{
			return false;
		}

		if (!ContainsPoint(x, y))
		{
			// 点击面板外部：收起面板（外部点击不再下传，避免误触其他控件）。
			Close();
			return true;
		}

		// 点击当前输入框以外的位置时提交输入。
		if (m_editField != EditField::NONE && !UiPointInRect(EditFieldRect(), static_cast<float>(x),
		                                                     static_cast<float>(y)))
		{
			EndEdit(true);
		}

		// 数值与色号文本优先于滑块：两者几何重叠时要能进入输入状态。
		for (int index = 0; index < 3; ++index)
		{
			if (UiPointInRect(m_values[static_cast<std::size_t>(index)], static_cast<float>(x),
			                  static_cast<float>(y)))
			{
				BeginEdit(static_cast<EditField>(index + 1));
				return true;
			}
		}
		if (UiPointInRect(m_hexRect, static_cast<float>(x), static_cast<float>(y)))
		{
			BeginEdit(EditField::HEX);
			return true;
		}

		// 色域方块与色相条：按下即取值，之后拖动持续更新。
		if (UiPointInRect(m_gamutRect, static_cast<float>(x), static_cast<float>(y)))
		{
			m_drag = DragTarget::GAMUT;
			ApplyGamut(static_cast<float>(x), static_cast<float>(y));
			return true;
		}
		if (UiPointInRect(m_hueRect, static_cast<float>(x), static_cast<float>(y)))
		{
			m_drag = DragTarget::HUE;
			ApplyHue(static_cast<float>(y));
			return true;
		}

		m_draggingSlider = SliderAtPoint(x, y);
		if (m_draggingSlider >= 0)
		{
			m_drag = DragTarget::SLIDER;
			ApplySlider(m_draggingSlider, static_cast<float>(x));
			return true;
		}
		return true;
	}

	bool ColorPickerPopup::OnLButtonUp()
	{
		if (!m_open || (m_draggingSlider < 0 && m_drag == DragTarget::NONE))
		{
			return false;
		}
		m_draggingSlider = -1;
		m_drag = DragTarget::NONE;
		return true;
	}

	bool ColorPickerPopup::OnKeyDown(WPARAM key)
	{
		if (!m_open)
		{
			return false;
		}
		if (m_editField != EditField::NONE)
		{
			const bool shift = (GetKeyState(VK_SHIFT) & 0x8000) != 0;
			const bool control = (GetKeyState(VK_CONTROL) & 0x8000) != 0;

			switch (key)
			{
			case VK_RETURN:
				EndEdit(true);
				return true;
			case VK_ESCAPE:
				EndEdit(false);
				return true;
			case VK_BACK:
				m_edit.Backspace();
				return true;
			case VK_DELETE:
				m_edit.DeleteForward();
				return true;
			case VK_LEFT:
				m_edit.MoveCaret(-1, shift);
				return true;
			case VK_RIGHT:
				m_edit.MoveCaret(1, shift);
				return true;
			case VK_HOME:
				m_edit.MoveHome(shift);
				return true;
			case VK_END:
				m_edit.MoveEnd(shift);
				return true;
			case 'A':
				if (control)
				{
					m_edit.SelectAll();
				}
				return true;
			default:
				break;
			}
			return true;
		}
		if (key == VK_ESCAPE)
		{
			Close();
		}
		return true;
	}

	void ColorPickerPopup::Paint(gd::Graphics& g)
	{
		if (!m_open || m_theme == nullptr || m_fonts == nullptr || m_rect.Width <= 0.0f)
		{
			return;
		}

		// 投影。
		UiFillRoundRect(g, gd::RectF(m_rect.X + 1.0f * m_scale, m_rect.Y + 2.0f * m_scale, m_rect.Width,
		                             m_rect.Height),
		                kCorner * m_scale, 0x14000000u);
		UiFillRoundRect(g, gd::RectF(m_rect.X + 2.0f * m_scale, m_rect.Y + 4.0f * m_scale, m_rect.Width,
		                             m_rect.Height),
		                kCorner * m_scale, 0x10000000u);

		UiFillRoundRect(g, m_rect, kCorner * m_scale, m_theme->cardBg);
		UiDrawRoundRect(g, m_rect, kCorner * m_scale, m_theme->borderStrong, 1.0f);

		UiText(g, L"自定义颜色", m_fonts->uiSmallBold, m_titleRect, m_theme->textMuted, TextAlign::LEFT);

		// ---- 色域方块（横轴饱和度、纵轴明度）----
		// 方块按当前色相预渲染到缓存位图里，避免每帧重画上百条渐变；
		// 色相变化时才重建一次。
		if (EnsureGamutCache())
		{
			g.DrawImage(m_gamutCache.get(), m_gamutRect);
		}
		UiDrawRoundRect(g, m_gamutRect, kSwatchCorner * m_scale, m_theme->border, kGamutBorder);

		// ---- 色相条（纵向 0-1）：6 段线性渐变拼出完整色相环 ----
		{
			for (int segment = 0; segment < 6; ++segment)
			{
				const double hue0 = static_cast<double>(segment) / 6.0;
				const double hue1 = static_cast<double>(segment + 1) / 6.0;
				const std::array<double, 3> rgb0 = FromHsv(hue0, 1.0, 1.0);
				const std::array<double, 3> rgb1 = FromHsv(hue1, 1.0, 1.0);
				const std::uint32_t color0 =
				    0xFF000000u | (ToByte(rgb0[0]) << 16) | (ToByte(rgb0[1]) << 8) | ToByte(rgb0[2]);
				const std::uint32_t color1 =
				    0xFF000000u | (ToByte(rgb1[0]) << 16) | (ToByte(rgb1[1]) << 8) | ToByte(rgb1[2]);

				const float top = m_hueRect.Y + m_hueRect.Height * static_cast<float>(hue0);
				const float bottom = m_hueRect.Y + m_hueRect.Height * static_cast<float>(hue1);
				const gd::Point from(static_cast<INT>(std::lround(m_hueRect.X)),
				                     static_cast<INT>(std::lround(top)));
				const gd::Point to(static_cast<INT>(std::lround(m_hueRect.X)),
				                   static_cast<INT>(std::lround(bottom)));
				gd::LinearGradientBrush brush(from, to, ToGdiColor(color0), ToGdiColor(color1));
				// 渐变端点会各自向两侧延伸半段，逐段微重叠地填充即可无缝拼接。
				g.FillRectangle(&brush, m_hueRect.X, top, m_hueRect.Width, bottom - top);
			}
			UiDrawRoundRect(g, m_hueRect, kSwatchCorner * m_scale, m_theme->border, kGamutBorder);

			// ---- 色域方块上的选点：中心就是当前选中的颜色，外面只加一圈白色描边 ----
			// 位置直接用保存的选点状态（不再从 RGB 反推，否则黑色会让选点弹回左侧）。
			const float markerX = m_gamutRect.X + static_cast<float>(m_sat) * m_gamutRect.Width;
			const float markerY = m_gamutRect.Y + static_cast<float>(1.0 - m_val) * m_gamutRect.Height;
			const float markerRadius = 5.5f * m_scale;
			gd::SolidBrush markerBrush(ToGdiColor(CurrentColor()));
			g.FillEllipse(&markerBrush, markerX - markerRadius, markerY - markerRadius,
			              markerRadius * 2.0f, markerRadius * 2.0f);
			gd::Pen markerPen(ToGdiColor(0xFFFFFFFFu), 2.0f * m_scale);
			g.DrawEllipse(&markerPen, markerX - markerRadius, markerY - markerRadius,
			              markerRadius * 2.0f, markerRadius * 2.0f);

			// ---- 色相条上的指示器：白色描边的圆角长方条，底色就是该位置的颜色 ----
			// 色相直接用保存值：色相 1 与 0 是同一个颜色（红），从 RGB 反推会归一到 0，
			// 表现为"把滑块拖到最下面却弹回最上面"。
			const double hue = CurrentHue();
			const std::array<double, 3> hueRgb = FromHsv(hue, 1.0, 1.0);
			const std::uint32_t hueColor =
			    0xFF000000u | (ToByte(hueRgb[0]) << 16) | (ToByte(hueRgb[1]) << 8) | ToByte(hueRgb[2]);
			const float hueMarkerY = m_hueRect.Y + static_cast<float>(hue) * m_hueRect.Height;
			const float pillHeight = 10.0f * m_scale;
			const float pillWidth = m_hueRect.Width + 9.0f * m_scale;
			const gd::RectF pill(m_hueRect.X + (m_hueRect.Width - pillWidth) * 0.5f,
			                     hueMarkerY - pillHeight * 0.5f, pillWidth, pillHeight);
			UiFillRoundRect(g, pill, pillHeight * 0.5f, hueColor);
			UiDrawRoundRect(g, pill, pillHeight * 0.5f, 0xFFFFFFFFu, 1.8f * m_scale);
		}

		for (int index = 0; index < 3; ++index)
		{
			const std::size_t slot = static_cast<std::size_t>(index);
			const gd::RectF& track = m_tracks[slot];

			// 通道标签放在滑块同一行的左侧，与轨道/数值纵向对齐。
			const gd::RectF labelRect(track.X - (kLabelWidth + kLabelGap) * m_scale, m_values[slot].Y,
			                          kLabelWidth * m_scale, kRowHeight * m_scale);
			UiText(g, kChannelNames[index], m_fonts->uiSmall, labelRect, m_theme->textMuted, TextAlign::LEFT);

			const bool active = (m_draggingSlider == index) || (m_hoverSlider == index);
			DrawChannelSlider(g, track, m_channels[slot], kChannelColors[index], active, m_scale);

			if (m_editField == static_cast<EditField>(index + 1))
			{
				UiDrawEditField(g, m_values[slot], m_edit, m_fonts->monoSmall, m_scale);
			}
			else
			{
				UiText(g, std::to_wstring(ToByte(m_channels[slot])), m_fonts->monoSmall, m_values[slot],
				       m_theme->text, TextAlign::RIGHT);
			}
		}

		// 预览与十六进制值。
		const std::uint32_t color = CurrentColor();
		UiFillRoundRect(g, m_previewRect, kSwatchCorner * m_scale, color);
		UiDrawRoundRect(g, m_previewRect, kSwatchCorner * m_scale, m_theme->borderStrong, 1.0f);

		if (m_editField == EditField::HEX)
		{
			UiDrawEditField(g, m_hexRect, m_edit, m_fonts->monoSmall, m_scale);
		}
		else
		{
			wchar_t buffer[16];
			swprintf(buffer, sizeof(buffer) / sizeof(buffer[0]), L"#%02X%02X%02X", (color >> 16) & 0xFFu,
			         (color >> 8) & 0xFFu, color & 0xFFu);
			UiText(g, std::wstring(buffer), m_fonts->monoSmall, m_hexRect, m_theme->text, TextAlign::LEFT);
		}
	}

} // namespace jdi