package tui

import tea "github.com/charmbracelet/bubbletea"

// Layout offsets for hit-testing the rendered views (see view.go). Every
// screen renders a title line then a blank line before its content, so content
// starts at headerRows. The grid is drawn with a border between cells, hence
// the +1s.
const (
	headerRows = 2          // title line + blank line
	cellStride = cellW + 1  // cell inner width + right border column
	blockH     = cellH + 1  // cell content rows + top border row
)

// handleMouse routes mouse events per screen. Enables click-to-select on the
// list screens and tmux-style click/drag editing in the layout grid.
func (m *model) handleMouse(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
	switch m.screen {
	case screenMenu, screenCameras, screenLayouts, screenSetActive:
		return m.mouseList(msg)
	case screenLayoutEdit:
		return m.mouseGridEdit(msg)
	case screenCameraPicker:
		return m.mousePicker(msg)
	}
	return m, nil
}

// cellAtMouse maps a screen position to a grid cell in the editor/picker.
func (m *model) cellAtMouse(x, y int) (col, row int, ok bool) {
	cols, rows := m.gridDims()
	if y < headerRows || x < 0 {
		return 0, 0, false
	}
	row = (y - headerRows) / blockH
	col = x / cellStride
	if row < 0 || row >= rows || col < 0 || col >= cols {
		return 0, 0, false
	}
	return col, row, true
}

// gridLineCount is how many terminal rows renderGrid emits.
func (m *model) gridLineCount() int {
	_, rows := m.gridDims()
	return rows*blockH + 1
}

// listLen is the number of selectable rows on the current list screen.
func (m *model) listLen() int {
	switch m.screen {
	case screenMenu:
		return len(menuItems)
	case screenCameras:
		return len(m.cfg.Cameras)
	case screenLayouts, screenSetActive:
		return len(m.cfg.Layouts)
	}
	return 0
}

// mouseList: left-click a row to select and activate it (same as pressing enter).
func (m *model) mouseList(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
	if msg.Action != tea.MouseActionRelease || msg.Button != tea.MouseButtonLeft {
		return m, nil
	}
	idx := msg.Y - headerRows
	if idx < 0 || idx >= m.listLen() {
		return m, nil
	}
	m.cursor = idx
	return m.handleKey(tea.KeyMsg{Type: tea.KeyEnter})
}

// mouseGridEdit implements tmux-style editing: click a cell to assign a camera,
// or press on a tile and drag to resize its span (grid-snapped).
func (m *model) mouseGridEdit(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
	if msg.Button != tea.MouseButtonLeft {
		return m, nil
	}
	col, row, ok := m.cellAtMouse(msg.X, msg.Y)
	switch msg.Action {
	case tea.MouseActionPress:
		if !ok {
			return m, nil
		}
		m.edCol, m.edRow = col, row
		m.dragTile = m.tileIndexAt(col, row)
		m.dragging = m.dragTile >= 0
		m.dragMoved = false

	case tea.MouseActionMotion:
		if !ok || !m.dragging {
			return m, nil
		}
		t := &m.curLayout().Tiles[m.dragTile]
		newCS, newRS := col-t.Col+1, row-t.Row+1
		// Only grow/shrink toward the bottom-right of the tile's origin.
		if newCS >= 1 && newRS >= 1 && m.regionFree(m.dragTile, t.Col, t.Row, newCS, newRS) {
			t.ColSpan, t.RowSpan = newCS, newRS
			m.edCol, m.edRow = col, row
			m.dragMoved = true
			m.dirty = true
		}

	case tea.MouseActionRelease:
		wasDrag := m.dragging && m.dragMoved
		m.dragging = false
		m.dragMoved = false
		// A plain click (no drag) opens the camera picker for that cell.
		if ok && !wasDrag {
			m.edCol, m.edRow = col, row
			m.screen, m.cursor = screenCameraPicker, 0
		}
	}
	return m, nil
}

// mousePicker: left-click an option to choose it.
func (m *model) mousePicker(msg tea.MouseMsg) (tea.Model, tea.Cmd) {
	if msg.Action != tea.MouseActionRelease || msg.Button != tea.MouseButtonLeft {
		return m, nil
	}
	// Options are drawn below the grid and a blank separator line.
	optStart := headerRows + m.gridLineCount() + 1
	idx := msg.Y - optStart
	if idx < 0 || idx >= len(m.pickerOptions()) {
		return m, nil
	}
	m.cursor = idx
	return m.handleKey(tea.KeyMsg{Type: tea.KeyEnter})
}