#include "TabBar.hpp"

#include <algorithm>
#include <cmath>

#include "Utf8Util.hpp"

namespace jdi
{

	namespace
	{
		const float kTabHeight = 32.0f;			/**< 标签高度（逻辑像素）。 */
		const float kTopMargin = 4.0f;			/**< 标签顶部留白。 */
		const float kLeftPadding = 8.0f;		/**< 左侧留白。 */
		const float kTabPadding = 14.0f;		/**< 标签文本左右内边距。 */
		const float kCloseSize = 16.0f;			/**< 关闭按钮尺寸。 */
		const float kCloseGap = 6.0f;			/**< 文本与关闭按钮间距。 */
		const float kAddSize = 24.0f;			/**< 新建按钮尺寸。 */
		const float kAddGap = 6.0f;				/**< 新建按钮与末个标签的间距。 */
		const float kCorner = 5.0f;				/**< 标签圆角半径。 */
		const float kMaxTabWidth = 200.0f;		/**< 单个标签最大宽度（逻辑像素）。 */
	}

	TabBar::TabBar() = default;

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

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

	void TabBar::SetTabs(const std::vector<std::wstring>& names)
	{
		m_tabs.clear();
		m_tabs.resize(names.size());
		for (std::size_t index = 0; index < names.size(); ++index)
		{
			m_tabs[index].name = names[index];
		}
		if (m_activeIndex >= static_cast<int>(m_tabs.size()))
		{
			m_activeIndex = m_tabs.empty() ? -1 : static_cast<int>(m_tabs.size()) - 1;
		}
		m_hoverIndex = -1;
		m_hoverClose = false;
	}

	void TabBar::SetActiveIndex(int index)
	{
		m_activeIndex = index;
	}

	float TabBar::DesiredHeight() const
	{
		return (kTabHeight + kTopMargin) * m_scale;
	}

	void TabBar::Layout(const gd::RectF& area)
	{
		m_area = area;
		if (m_fonts == nullptr || m_fonts->ui == nullptr)
		{
			return;
		}

		const float tabHeight = kTabHeight * m_scale;
		const float top = area.Y + kTopMargin * m_scale;
		const float closeSize = kCloseSize * m_scale;
		const float maxWidth = kMaxTabWidth * m_scale;
		const float minWidth = 70.0f * m_scale;

		float cursorX = area.X + kLeftPadding * m_scale;

		for (TabItem& tab : m_tabs)
		{
			const float textWidth = UiMeasureTextWidth(m_fonts->ui, tab.name);
			float width = kTabPadding * 2.0f * m_scale + textWidth + kCloseGap * m_scale + closeSize;
			width = std::max(minWidth, std::min(width, maxWidth));

			tab.rect = gd::RectF(cursorX, top, width, tabHeight);
			tab.closeRect = gd::RectF(cursorX + width - kTabPadding * m_scale - closeSize,
			                          top + (tabHeight - closeSize) * 0.5f, closeSize, closeSize);

			cursorX += width + kAddGap * m_scale;
		}

		const float addSize = kAddSize * m_scale;
		m_addRect = gd::RectF(cursorX, top + (tabHeight - addSize) * 0.5f, addSize, addSize);
	}

	void TabBar::Paint(gd::Graphics& g)
	{
		if (m_theme == nullptr || m_fonts == nullptr)
		{
			return;
		}

		UiFillRect(g, m_area, m_theme->panelBg);

		const float closeIconSize = 8.0f * m_scale;

		for (std::size_t index = 0; index < m_tabs.size(); ++index)
		{
			const TabItem& tab = m_tabs[index];
			const bool active = (static_cast<int>(index) == m_activeIndex);
			const bool hovered = (static_cast<int>(index) == m_hoverIndex);

			std::uint32_t background = m_theme->panelBg;
			if (active)
			{
				background = m_theme->cardBg;
			}
			else if (hovered)
			{
				background = m_theme->hover;
			}
			UiFillRoundRect(g, tab.rect, kCorner * m_scale, background);

			if (!active)
			{
				UiDrawRoundRect(g, tab.rect, kCorner * m_scale, m_theme->border, 1.0f);
			}
			else
			{
				// 激活页使用顶部强调条指示。
				UiFillRoundRect(g, gd::RectF(tab.rect.X + kCorner * m_scale, tab.rect.Y,
				                             tab.rect.Width - kCorner * 2.0f * m_scale, 2.5f * m_scale),
				                1.0f * m_scale, m_theme->accent);
			}

			const float textLeft = tab.rect.X + kTabPadding * m_scale;
			const float textWidth = tab.closeRect.X - kCloseGap * m_scale - textLeft;

			// 重命名编辑态：在标签本体之上叠加输入框（标签底色与边框仍然保留）。
			if (static_cast<int>(index) == m_editIndex)
			{
				const gd::RectF editRect(textLeft - 3.0f * m_scale, tab.rect.Y + 3.0f * m_scale,
				                         std::max(40.0f, textWidth + 6.0f * m_scale),
				                         tab.rect.Height - 6.0f * m_scale);
				UiDrawEditField(g, editRect, m_edit, m_fonts->ui, m_scale);
			}
			else
			{
				const std::wstring label = UiEllipsize(g, tab.name, m_fonts->ui, std::max(8.0f, textWidth));
				UiText(g, label, active ? m_fonts->uiBold : m_fonts->ui,
				       gd::RectF(textLeft, tab.rect.Y, std::max(8.0f, textWidth), tab.rect.Height),
				       active ? m_theme->textStrong : m_theme->text, TextAlign::LEFT);
			}

			// 关闭按钮：悬停时显示底色，图标始终可见。
			const bool closeHot = hovered && m_hoverClose;
			if (closeHot)
			{
				UiFillRoundRect(g, tab.closeRect, 3.0f * m_scale, m_theme->pressed);
			}
			const float cx = tab.closeRect.X + tab.closeRect.Width * 0.5f;
			const float cy = tab.closeRect.Y + tab.closeRect.Height * 0.5f;
			const std::uint32_t iconColor =
			    closeHot ? m_theme->danger : (active ? m_theme->text : m_theme->textMuted);
			UiDrawLine(g, cx - closeIconSize * 0.5f, cy - closeIconSize * 0.5f, cx + closeIconSize * 0.5f,
			           cy + closeIconSize * 0.5f, iconColor, 1.4f * m_scale);
			UiDrawLine(g, cx + closeIconSize * 0.5f, cy - closeIconSize * 0.5f, cx - closeIconSize * 0.5f,
			           cy + closeIconSize * 0.5f, iconColor, 1.4f * m_scale);
		}

		// 拖拽排序时在插入位置绘制强调色指示条。
		if (m_dragIndex >= 0 && m_dragMoved && !m_tabs.empty())
		{
			const int drop = DropIndexAt(m_dragMouseX);
			float markerX = m_addRect.X;
			if (drop < static_cast<int>(m_tabs.size()))
			{
				markerX = m_tabs[static_cast<std::size_t>(drop)].rect.X - kAddGap * m_scale * 0.5f;
			}

			const float top = m_area.Y + kTopMargin * m_scale;
			const float bottom = top + kTabHeight * m_scale;
			UiFillRoundRect(g, gd::RectF(markerX - 1.5f * m_scale, top, 3.0f * m_scale, bottom - top),
			                1.5f * m_scale, m_theme->accent);
		}

		// 新建按钮。
		const std::uint32_t addBg = m_hoverAdd ? m_theme->hover : m_theme->panelBg;
		UiFillRoundRect(g, m_addRect, kCorner * m_scale, addBg);
		UiDrawRoundRect(g, m_addRect, kCorner * m_scale, m_theme->border, 1.0f);

		const float ax = m_addRect.X + m_addRect.Width * 0.5f;
		const float ay = m_addRect.Y + m_addRect.Height * 0.5f;
		const float armLength = 4.5f * m_scale;
		const std::uint32_t addColor = m_hoverAdd ? m_theme->accent : m_theme->text;
		UiDrawLine(g, ax - armLength, ay, ax + armLength, ay, addColor, 1.6f * m_scale);
		UiDrawLine(g, ax, ay - armLength, ax, ay + armLength, addColor, 1.6f * m_scale);

		// 底部分隔线。
		UiDrawLine(g, m_area.X, m_area.Y + m_area.Height - 1.0f, m_area.X + m_area.Width,
		           m_area.Y + m_area.Height - 1.0f, m_theme->border, 1.0f);
	}

	bool TabBar::HitTest(int x, int y) const
	{
		return UiPointInRect(m_area, static_cast<float>(x), static_cast<float>(y));
	}

	int TabBar::TabAtPoint(int x, int y) const
	{
		const float fx = static_cast<float>(x);
		const float fy = static_cast<float>(y);
		for (std::size_t index = 0; index < m_tabs.size(); ++index)
		{
			if (UiPointInRect(m_tabs[index].rect, fx, fy))
			{
				return static_cast<int>(index);
			}
		}
		return -1;
	}

	bool TabBar::OnMouseMove(int x, int y)
	{
		// 拖动排序中：只跟踪鼠标位置，由界面层绘制插入指示。
		if (m_dragIndex >= 0)
		{
			if (x != m_dragMouseX)
			{
				m_dragMouseX = x;
				m_dragMoved = true;
				return true;
			}
			return false;
		}

		const int index = TabAtPoint(x, y);
		const bool overClose =
		    (index >= 0 && UiPointInRect(m_tabs[static_cast<std::size_t>(index)].closeRect,
		                                 static_cast<float>(x), static_cast<float>(y)));
		const bool overAdd = UiPointInRect(m_addRect, static_cast<float>(x), static_cast<float>(y));

		if (index == m_hoverIndex && overClose == m_hoverClose && overAdd == m_hoverAdd)
		{
			return false;
		}
		m_hoverIndex = index;
		m_hoverClose = overClose;
		m_hoverAdd = overAdd;
		return true;
	}

	bool TabBar::OnLButtonDown(int x, int y)
	{
		m_pressedIndex = -1;
		m_pressedClose = false;
		m_pressedAdd = false;

		// 编辑态下点击其它位置先提交重命名。
		if (IsEditing())
		{
			TabBarResult ignored;
			OnEditKey(VK_RETURN, ignored);
		}

		if (UiPointInRect(m_addRect, static_cast<float>(x), static_cast<float>(y)))
		{
			m_pressedAdd = true;
			return true;
		}

		const int index = TabAtPoint(x, y);
		if (index < 0)
		{
			return false;
		}

		m_pressedIndex = index;
		m_dragIndex = index;
		m_dragMouseX = x;
		m_pressedX = x;
		m_dragMoved = false;
		m_pressedClose = UiPointInRect(m_tabs[static_cast<std::size_t>(index)].closeRect,
		                              static_cast<float>(x), static_cast<float>(y));

		// 自行判定双击：不依赖系统 WM_LBUTTONDBLCLK，行为在不同环境下更一致。
		const DWORD now = GetTickCount();
		const bool sameTab = (index == m_lastClickIndex);
		const DWORD elapsed = now - m_lastClickTick;
		if (!m_pressedClose && sameTab && elapsed <= GetDoubleClickTime())
		{
			m_lastClickIndex = -1;
			OnDoubleClick(x, y);
			return true;
		}
		m_lastClickIndex = m_pressedClose ? -1 : index;
		m_lastClickTick = now;
		return true;
	}

	bool TabBar::OnLButtonUp(int x, int y, TabBarResult& result)
	{
		result = TabBarResult();

		if (m_pressedAdd)
		{
			m_pressedAdd = false;
			if (UiPointInRect(m_addRect, static_cast<float>(x), static_cast<float>(y)))
			{
				result.type = TabBarResult::Type::ADD;
			}
			return true;
		}

		if (m_pressedIndex < 0)
		{
			m_dragIndex = -1;
			return false;
		}

		const int index = m_pressedIndex;
		const bool wasClose = m_pressedClose;
		const bool dragged = m_dragMoved && (std::abs(x - m_pressedX) > 3);
		m_pressedIndex = -1;
		m_pressedClose = false;
		m_dragIndex = -1;
		m_dragMoved = false;

		// 拖动超过阈值：按释放位置重新排序。
		if (dragged && !wasClose)
		{
			const int target = DropIndexAt(x);
			if (target >= 0 && target != index && target != index + 1)
			{
				result.type = TabBarResult::Type::REORDER;
				result.index = index;
				result.targetIndex = target;
			}
			return true;
		}

		if (TabAtPoint(x, y) != index)
		{
			return true;
		}

		if (wasClose)
		{
			result.type = TabBarResult::Type::CLOSE;
			result.index = index;
		}
		else
		{
			result.type = TabBarResult::Type::SELECT;
			result.index = index;
		}
		return true;
	}

	int TabBar::DropIndexAt(int x) const
	{
		const float fx = static_cast<float>(x);
		for (std::size_t index = 0; index < m_tabs.size(); ++index)
		{
			const gd::RectF& rect = m_tabs[index].rect;
			if (fx < rect.X + rect.Width * 0.5f)
			{
				return static_cast<int>(index);
			}
		}
		return static_cast<int>(m_tabs.size());
	}

	bool TabBar::OnDoubleClick(int x, int y)
	{
		const int index = TabAtPoint(x, y);
		if (index < 0)
		{
			return false;
		}
		// 双击关闭按钮不进入重命名。
		if (UiPointInRect(m_tabs[static_cast<std::size_t>(index)].closeRect, static_cast<float>(x),
		                  static_cast<float>(y)))
		{
			return false;
		}

		m_editIndex = index;
		m_edit.Begin(m_tabs[static_cast<std::size_t>(index)].name, true, EditFilter::ANY, 48);
		return true;
	}

	bool TabBar::OnEditChar(wchar_t character)
	{
		if (m_editIndex < 0)
		{
			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_host);
			return false;
		case 0x18: // Ctrl+X
			return m_edit.CutToClipboard(m_host);
		case 0x16: // Ctrl+V
			return m_edit.PasteFromClipboard(m_host);
		case 0x01: // Ctrl+A
			m_edit.SelectAll();
			return true;
		default:
			break;
		}

		if (character == L'\r' || character == L'\n')
		{
			TabBarResult result;
			OnEditKey(VK_RETURN, result);
			return true;
		}
		if (character == L'\b')
		{
			return m_edit.Backspace();
		}
		if (character == 0x7F)
		{
			return m_edit.DeleteForward();
		}
		if (character < L' ')
		{
			return false;
		}
		return m_edit.Insert(character);
	}

	bool TabBar::OnEditKey(WPARAM key, TabBarResult& result)
	{
		result = TabBarResult();
		if (m_editIndex < 0)
		{
			return false;
		}

		const int index = m_editIndex;
		const bool shift = (GetKeyState(VK_SHIFT) & 0x8000) != 0;
		const bool control = (GetKeyState(VK_CONTROL) & 0x8000) != 0;

		switch (key)
		{
		case VK_RETURN:
		{
			const std::wstring text = Trim(m_edit.Text());
			m_editIndex = -1;
			m_edit.End();
			if (!text.empty())
			{
				result.type = TabBarResult::Type::RENAME;
				result.index = index;
				result.text = text;
			}
			return true;
		}
		case VK_ESCAPE:
			m_editIndex = -1;
			m_edit.End();
			return true;
		case VK_BACK:
			return m_edit.Backspace();
		case VK_DELETE:
			return m_edit.DeleteForward();
		case VK_LEFT:
			return m_edit.MoveCaret(-1, shift);
		case VK_RIGHT:
			return m_edit.MoveCaret(1, shift);
		case VK_HOME:
			return m_edit.MoveHome(shift);
		case VK_END:
			return m_edit.MoveEnd(shift);
		case 'A':
			if (control)
			{
				m_edit.SelectAll();
			}
			return true;
		default:
			break;
		}
		return true;
	}

	bool TabBar::OnRButtonDown(int x, int y, int screenX, int screenY, TabBarResult& result)
	{
		result = TabBarResult();

		const int index = TabAtPoint(x, y);
		if (index < 0)
		{
			return false;
		}

		result.type = TabBarResult::Type::CONTEXT;
		result.index = index;
		result.screenX = screenX;
		result.screenY = screenY;
		return true;
	}

	bool TabBar::OnMouseLeave()
	{
		if (m_hoverIndex < 0 && !m_hoverClose && !m_hoverAdd)
		{
			return false;
		}
		m_hoverIndex = -1;
		m_hoverClose = false;
		m_hoverAdd = false;
		return true;
	}

} // namespace jdi