tview/table.go

package tview

import (
	"sort"

	"github.com/gdamore/tcell/v2"
	colorful "github.com/lucasb-eyer/go-colorful"
)

// TableCell represents one cell inside a Table. You can instantiate this type
// directly but all colors (background and text) will be set to their default
// which is black.
type TableCell struct {
	// The reference object.
	Reference interface{}

	// The text to be displayed in the table cell.
	Text string

	// The alignment of the cell text. One of AlignLeft (default), AlignCenter,
	// or AlignRight.
	Align int

	// The maximum width of the cell in screen space. This is used to give a
	// column a maximum width. Any cell text whose screen width exceeds this width
	// is cut off. Set to 0 if there is no maximum width.
	MaxWidth int

	// If the total table width is less than the available width, this value is
	// used to add extra width to a column. See SetExpansion() for details.
	Expansion int

	// The color of the cell text.
	Color tcell.Color

	// The background color of the cell.
	BackgroundColor tcell.Color

	// If set to true, the BackgroundColor is not used and the cell will have
	// the background color of the table.
	Transparent bool

	// The style attributes of the cell.
	Attributes tcell.AttrMask

	// If set to true, this cell cannot be selected.
	NotSelectable bool

	// An optional handler for mouse clicks. This also fires if the cell is not
	// selectable. If true is returned, no additional "selected" event is fired
	// on selectable cells.
	Clicked func() bool

	// The position and width of the cell the last time table was drawn.
	x, y, width int
}

// NewTableCell returns a new table cell with sensible defaults. That is, left
// aligned text with the primary text color (see Styles) and a transparent
// background (using the background of the Table).
func NewTableCell(text string) *TableCell {
	return &TableCell{
		Text:            text,
		Align:           AlignLeft,
		Color:           Styles.PrimaryTextColor,
		BackgroundColor: Styles.PrimitiveBackgroundColor,
		Transparent:     true,
	}
}

// SetText sets the cell's text.
func (c *TableCell) SetText(text string) *TableCell {
	c.Text = text
	return c
}

// SetAlign sets the cell's text alignment, one of AlignLeft, AlignCenter, or
// AlignRight.
func (c *TableCell) SetAlign(align int) *TableCell {
	c.Align = align
	return c
}

// SetMaxWidth sets maximum width of the cell in screen space. This is used to
// give a column a maximum width. Any cell text whose screen width exceeds this
// width is cut off. Set to 0 if there is no maximum width.
func (c *TableCell) SetMaxWidth(maxWidth int) *TableCell {
	c.MaxWidth = maxWidth
	return c
}

// SetExpansion sets the value by which the column of this cell expands if the
// available width for the table is more than the table width (prior to applying
// this expansion value). This is a proportional value. The amount of unused
// horizontal space is divided into widths to be added to each column. How much
// extra width a column receives depends on the expansion value: A value of 0
// (the default) will not cause the column to increase in width. Other values
// are proportional, e.g. a value of 2 will cause a column to grow by twice
// the amount of a column with a value of 1.
//
// Since this value affects an entire column, the maximum over all visible cells
// in that column is used.
//
// This function panics if a negative value is provided.
func (c *TableCell) SetExpansion(expansion int) *TableCell {
	if expansion < 0 {
		panic("Table cell expansion values may not be negative")
	}
	c.Expansion = expansion
	return c
}

// SetTextColor sets the cell's text color.
func (c *TableCell) SetTextColor(color tcell.Color) *TableCell {
	c.Color = color
	return c
}

// SetBackgroundColor sets the cell's background color. This will also cause the
// cell's Transparent flag to be set to "false".
func (c *TableCell) SetBackgroundColor(color tcell.Color) *TableCell {
	c.BackgroundColor = color
	c.Transparent = false
	return c
}

// SetTransparency sets the background transparency of this cell. A value of
// "true" will cause the cell to use the table's background color. A value of
// "false" will cause it to use its own background color.
func (c *TableCell) SetTransparency(transparent bool) *TableCell {
	c.Transparent = transparent
	return c
}

// SetAttributes sets the cell's text attributes. You can combine different
// attributes using bitmask operations:
//
//   cell.SetAttributes(tcell.AttrUnderline | tcell.AttrBold)
func (c *TableCell) SetAttributes(attr tcell.AttrMask) *TableCell {
	c.Attributes = attr
	return c
}

// SetStyle sets the cell's style (foreground color, background color, and
// attributes) all at once.
func (c *TableCell) SetStyle(style tcell.Style) *TableCell {
	c.Color, c.BackgroundColor, c.Attributes = style.Decompose()
	return c
}

// SetSelectable sets whether or not this cell can be selected by the user.
func (c *TableCell) SetSelectable(selectable bool) *TableCell {
	c.NotSelectable = !selectable
	return c
}

// SetReference allows you to store a reference of any type in this cell. This
// will allow you to establish a mapping between the cell and your
// actual data.
func (c *TableCell) SetReference(reference interface{}) *TableCell {
	c.Reference = reference
	return c
}

// GetReference returns this cell's reference object.
func (c *TableCell) GetReference() interface{} {
	return c.Reference
}

// GetLastPosition returns the position of the table cell the last time it was
// drawn on screen. If the cell is not on screen, the return values are
// undefined.
//
// Because the Table class will attempt to keep selected cells on screen, this
// function is most useful in response to a "selected" event (see
// SetSelectedFunc()) or a "selectionChanged" event (see
// SetSelectionChangedFunc()).
func (c *TableCell) GetLastPosition() (x, y, width int) {
	return c.x, c.y, c.width
}

// SetClickedFunc sets a handler which fires when this cell is clicked. This is
// independent of whether the cell is selectable or not. But for selectable
// cells, if the function returns "true", the "selected" event is not fired.
func (c *TableCell) SetClickedFunc(clicked func() bool) *TableCell {
	c.Clicked = clicked
	return c
}

// TableContent defines a Table's data. You may replace a Table's default
// implementation with your own using the Table.SetContent() function. This will
// allow you to turn Table into a view of your own data structure. The
// Table.Draw() function, which is called when the screen is updated, will then
// use the (read-only) functions of this interface to update the table. The
// write functions are only called when the corresponding functions of Table are
// called.
//
// The interface's read-only functions are not called concurrently by the
// package (provided that users of the package don't call Table.Draw() in a
// separate goroutine, which would be uncommon and is not encouraged).
type TableContent interface {
	// Return the cell at the given position or nil if there is no cell. The
	// row and column arguments start at 0 and end at what GetRowCount() and
	// GetColumnCount() return, minus 1.
	GetCell(row, column int) *TableCell

	// Return the total number of rows in the table.
	GetRowCount() int

	// Return the total number of columns in the table.
	GetColumnCount() int

	// The following functions are provided for completeness reasons as the
	// original Table implementation was not read-only. If you do not wish to
	// forward modifying operations to your data, you may opt to leave these
	// functions empty. To make this easier, you can include the
	// TableContentReadOnly type in your struct. See also the
	// demos/table/virtualtable example.

	// Set the cell at the given position to the provided cell.
	SetCell(row, column int, cell *TableCell)

	// Remove the row at the given position by shifting all following rows up
	// by one. Out of range positions may be ignored.
	RemoveRow(row int)

	// Remove the column at the given position by shifting all following columns
	// left by one. Out of range positions may be ignored.
	RemoveColumn(column int)

	// Insert a new empty row at the given position by shifting all rows at that
	// position and below down by one. Implementers may decide what to do with
	// out of range positions.
	InsertRow(row int)

	// Insert a new empty column at the given position by shifting all columns
	// at that position and to the right by one to the right. Implementers may
	// decide what to do with out of range positions.
	InsertColumn(column int)

	// Remove all table data.
	Clear()
}

// TableContentReadOnly is an empty struct which implements the write operations
// of the TableContent interface. None of the implemented functions do anything.
// You can embed this struct into your own structs to free yourself from having
// to implement the empty write functions of TableContent. See
// demos/table/virtualtable for an example.
type TableContentReadOnly struct{}

// SetCell does not do anything.
func (t TableContentReadOnly) SetCell(row, column int, cell *TableCell) {
	// nop.
}

// RemoveRow does not do anything.
func (t TableContentReadOnly) RemoveRow(row int) {
	// nop.
}

// RemoveColumn does not do anything.
func (t TableContentReadOnly) RemoveColumn(column int) {
	// nop.
}

// InsertRow does not do anything.
func (t TableContentReadOnly) InsertRow(row int) {
	// nop.
}

// InsertColumn does not do anything.
func (t TableContentReadOnly) InsertColumn(column int) {
	// nop.
}

// Clear does not do anything.
func (t TableContentReadOnly) Clear() {
	// nop.
}

// tableDefaultContent implements the default TableContent interface for the
// Table class.
type tableDefaultContent struct {
	// The cells of the table. Rows first, then columns.
	cells [][]*TableCell

	// The rightmost column in the data set.
	lastColumn int
}

// Clear clears all data.
func (t *tableDefaultContent) Clear() {
	t.cells = nil
	t.lastColumn = -1
}

// SetCell sets a cell's content.
func (t *tableDefaultContent) SetCell(row, column int, cell *TableCell) {
	if row >= len(t.cells) {
		t.cells = append(t.cells, make([][]*TableCell, row-len(t.cells)+1)...)
	}
	rowLen := len(t.cells[row])
	if column >= rowLen {
		t.cells[row] = append(t.cells[row], make([]*TableCell, column-rowLen+1)...)
		for c := rowLen; c < column; c++ {
			t.cells[row][c] = &TableCell{}
		}
	}
	t.cells[row][column] = cell
	if column > t.lastColumn {
		t.lastColumn = column
	}
}

// RemoveRow removes a row from the data.
func (t *tableDefaultContent) RemoveRow(row int) {
	if row < 0 || row >= len(t.cells) {
		return
	}
	t.cells = append(t.cells[:row], t.cells[row+1:]...)
}

// RemoveColumn removes a column from the data.
func (t *tableDefaultContent) RemoveColumn(column int) {
	for row := range t.cells {
		if column < 0 || column >= len(t.cells[row]) {
			continue
		}
		t.cells[row] = append(t.cells[row][:column], t.cells[row][column+1:]...)
	}
}

// InsertRow inserts a new row at the given position.
func (t *tableDefaultContent) InsertRow(row int) {
	if row >= len(t.cells) {
		return
	}
	t.cells = append(t.cells, nil)       // Extend by one.
	copy(t.cells[row+1:], t.cells[row:]) // Shift down.
	t.cells[row] = nil                   // New row is uninitialized.
}

// InsertColumn inserts a new column at the given position.
func (t *tableDefaultContent) InsertColumn(column int) {
	for row := range t.cells {
		if column >= len(t.cells[row]) {
			continue
		}
		t.cells[row] = append(t.cells[row], nil)             // Extend by one.
		copy(t.cells[row][column+1:], t.cells[row][column:]) // Shift to the right.
		t.cells[row][column] = &TableCell{}                  // New element is an uninitialized table cell.
	}
}

// GetCell returns the cell at the given position.
func (t *tableDefaultContent) GetCell(row, column int) *TableCell {
	if row < 0 || column < 0 || row >= len(t.cells) || column >= len(t.cells[row]) {
		return nil
	}
	return t.cells[row][column]
}

// GetRowCount returns the number of rows in the data set.
func (t *tableDefaultContent) GetRowCount() int {
	return len(t.cells)
}

// GetColumnCount returns the number of columns in the data set.
func (t *tableDefaultContent) GetColumnCount() int {
	if len(t.cells) == 0 {
		return 0
	}
	return t.lastColumn + 1
}

// Table visualizes two-dimensional data consisting of rows and columns. Each
// Table cell is defined via SetCell() by the TableCell type. They can be added
// dynamically to the table and changed any time.
//
// The most compact display of a table is without borders. Each row will then
// occupy one row on screen and columns are separated by the rune defined via
// SetSeparator() (a space character by default).
//
// When borders are turned on (via SetBorders()), each table cell is surrounded
// by lines. Therefore one table row will require two rows on screen.
//
// Columns will use as much horizontal space as they need. You can constrain
// their size with the MaxWidth parameter of the TableCell type.
//
// Fixed Columns
//
// You can define fixed rows and rolumns via SetFixed(). They will always stay
// in their place, even when the table is scrolled. Fixed rows are always the
// top rows. Fixed columns are always the leftmost columns.
//
// Selections
//
// You can call SetSelectable() to set columns and/or rows to "selectable". If
// the flag is set only for columns, entire columns can be selected by the user.
// If it is set only for rows, entire rows can be selected. If both flags are
// set, individual cells can be selected. The "selected" handler set via
// SetSelectedFunc() is invoked when the user presses Enter on a selection.
//
// Navigation
//
// If the table extends beyond the available space, it can be navigated with
// key bindings similar to Vim:
//
//   - h, left arrow: Move left by one column.
//   - l, right arrow: Move right by one column.
//   - j, down arrow: Move down by one row.
//   - k, up arrow: Move up by one row.
//   - g, home: Move to the top.
//   - G, end: Move to the bottom.
//   - Ctrl-F, page down: Move down by one page.
//   - Ctrl-B, page up: Move up by one page.
//
// When there is no selection, this affects the entire table (except for fixed
// rows and columns). When there is a selection, the user moves the selection.
// The class will attempt to keep the selection from moving out of the screen.
//
// Use SetInputCapture() to override or modify keyboard input.
//
// See https://github.com/rivo/tview/wiki/Table for an example.
type Table struct {
	*Box

	// Whether or not this table has borders around each cell.
	borders bool

	// The color of the borders or the separator.
	bordersColor tcell.Color

	// If there are no borders, the column separator.
	separator rune

	// The table's data structure.
	content TableContent

	// If true, when calculating the widths of the columns, all rows are evaluated
	// instead of only the visible ones.
	evaluateAllRows bool

	// The number of fixed rows / columns.
	fixedRows, fixedColumns int

	// Whether or not rows or columns can be selected. If both are set to true,
	// cells can be selected.
	rowsSelectable, columnsSelectable bool

	// The currently selected row and column.
	selectedRow, selectedColumn int

	// A temporary flag which causes the next call to Draw() to force the
	// current selection to remain visible. It is set to false afterwards.
	clampToSelection bool

	// If set to true, moving the selection will wrap around horizontally (last
	// to first column and vice versa) or vertically (last to first row and vice
	// versa).
	wrapHorizontally, wrapVertically bool

	// The number of rows/columns by which the table is scrolled down/to the
	// right.
	rowOffset, columnOffset int

	// If set to true, the table's last row will always be visible.
	trackEnd bool

	// The number of visible rows the last time the table was drawn.
	visibleRows int

	// The indices of the visible columns as of the last time the table was drawn.
	visibleColumnIndices []int

	// The net widths of the visible columns as of the last time the table was
	// drawn.
	visibleColumnWidths []int

	// The style of the selected rows. If this value is the empty struct,
	// selected rows are simply inverted.
	selectedStyle tcell.Style

	// An optional function which gets called when the user presses Enter on a
	// selected cell. If entire rows selected, the column value is undefined.
	// Likewise for entire columns.
	selected func(row, column int)

	// An optional function which gets called when the user changes the selection.
	// If entire rows selected, the column value is undefined.
	// Likewise for entire columns.
	selectionChanged func(row, column int)

	// An optional function which gets called when the user presses Escape, Tab,
	// or Backtab. Also when the user presses Enter if nothing is selectable.
	done func(key tcell.Key)
}

// NewTable returns a new table.
func NewTable() *Table {
	t := &Table{
		Box:          NewBox(),
		bordersColor: Styles.GraphicsColor,
		separator:    ' ',
	}
	t.SetContent(nil)
	return t
}

// SetContent sets a new content type for this table. This allows you to back
// the table by a data structure of your own, for example one that cannot be
// fully held in memory. For details, see the TableContent interface
// documentation.
//
// A value of nil will return the table to its default implementation where all
// of its table cells are kept in memory.
func (t *Table) SetContent(content TableContent) *Table {
	if content != nil {
		t.content = content
	} else {
		t.content = &tableDefaultContent{
			lastColumn: -1,
		}
	}
	return t
}

// Clear removes all table data.
func (t *Table) Clear() *Table {
	t.content.Clear()
	return t
}

// SetBorders sets whether or not each cell in the table is surrounded by a
// border.
func (t *Table) SetBorders(show bool) *Table {
	t.borders = show
	return t
}

// SetBordersColor sets the color of the cell borders.
func (t *Table) SetBordersColor(color tcell.Color) *Table {
	t.bordersColor = color
	return t
}

// SetSelectedStyle sets a specific style for selected cells. If no such style
// is set, per default, selected cells are inverted (i.e. their foreground and
// background colors are swapped).
//
// To reset a previous setting to its default, make the following call:
//
//   table.SetSelectedStyle(tcell.Style{})
func (t *Table) SetSelectedStyle(style tcell.Style) *Table {
	t.selectedStyle = style
	return t
}

// SetSeparator sets the character used to fill the space between two
// neighboring cells. This is a space character ' ' per default but you may
// want to set it to Borders.Vertical (or any other rune) if the column
// separation should be more visible. If cell borders are activated, this is
// ignored.
//
// Separators have the same color as borders.
func (t *Table) SetSeparator(separator rune) *Table {
	t.separator = separator
	return t
}

// SetFixed sets the number of fixed rows and columns which are always visible
// even when the rest of the cells are scrolled out of view. Rows are always the
// top-most ones. Columns are always the left-most ones.
func (t *Table) SetFixed(rows, columns int) *Table {
	t.fixedRows, t.fixedColumns = rows, columns
	return t
}

// SetSelectable sets the flags which determine what can be selected in a table.
// There are three selection modi:
//
//   - rows = false, columns = false: Nothing can be selected.
//   - rows = true, columns = false: Rows can be selected.
//   - rows = false, columns = true: Columns can be selected.
//   - rows = true, columns = true: Individual cells can be selected.
func (t *Table) SetSelectable(rows, columns bool) *Table {
	t.rowsSelectable, t.columnsSelectable = rows, columns
	return t
}

// GetSelectable returns what can be selected in a table. Refer to
// SetSelectable() for details.
func (t *Table) GetSelectable() (rows, columns bool) {
	return t.rowsSelectable, t.columnsSelectable
}

// GetSelection returns the position of the current selection.
// If entire rows are selected, the column index is undefined.
// Likewise for entire columns.
func (t *Table) GetSelection() (row, column int) {
	return t.selectedRow, t.selectedColumn
}

// Select sets the selected cell. Depending on the selection settings
// specified via SetSelectable(), this may be an entire row or column, or even
// ignored completely. The "selection changed" event is fired if such a callback
// is available (even if the selection ends up being the same as before and even
// if cells are not selectable).
func (t *Table) Select(row, column int) *Table {
	t.selectedRow, t.selectedColumn = row, column
	t.clampToSelection = true
	if t.selectionChanged != nil {
		t.selectionChanged(row, column)
	}
	return t
}

// SetOffset sets how many rows and columns should be skipped when drawing the
// table. This is useful for large tables that do not fit on the screen.
// Navigating a selection can change these values.
//
// Fixed rows and columns are never skipped.
func (t *Table) SetOffset(row, column int) *Table {
	t.rowOffset, t.columnOffset = row, column
	t.trackEnd = false
	return t
}

// GetOffset returns the current row and column offset. This indicates how many
// rows and columns the table is scrolled down and to the right.
func (t *Table) GetOffset() (row, column int) {
	return t.rowOffset, t.columnOffset
}

// SetEvaluateAllRows sets a flag which determines the rows to be evaluated when
// calculating the widths of the table's columns. When false, only visible rows
// are evaluated. When true, all rows in the table are evaluated.
//
// Set this flag to true to avoid shifting column widths when the table is
// scrolled. (May come with a performance penalty for large tables.)
//
// Use with caution on very large tables, especially those not backed by the
// default TableContent data structure.
func (t *Table) SetEvaluateAllRows(all bool) *Table {
	t.evaluateAllRows = all
	return t
}

// SetSelectedFunc sets a handler which is called whenever the user presses the
// Enter key on a selected cell/row/column. The handler receives the position of
// the selection and its cell contents. If entire rows are selected, the column
// index is undefined. Likewise for entire columns.
func (t *Table) SetSelectedFunc(handler func(row, column int)) *Table {
	t.selected = handler
	return t
}

// SetSelectionChangedFunc sets a handler which is called whenever the current
// selection changes. The handler receives the position of the new selection.
// If entire rows are selected, the column index is undefined. Likewise for
// entire columns.
func (t *Table) SetSelectionChangedFunc(handler func(row, column int)) *Table {
	t.selectionChanged = handler
	return t
}

// SetDoneFunc sets a handler which is called whenever the user presses the
// Escape, Tab, or Backtab key. If nothing is selected, it is also called when
// user presses the Enter key (because pressing Enter on a selection triggers
// the "selected" handler set via SetSelectedFunc()).
func (t *Table) SetDoneFunc(handler func(key tcell.Key)) *Table {
	t.done = handler
	return t
}

// SetCell sets the content of a cell the specified position. It is ok to
// directly instantiate a TableCell object. If the cell has content, at least
// the Text and Color fields should be set.
//
// Note that setting cells in previously unknown rows and columns will
// automatically extend the internal table representation with empty TableCell
// objects, e.g. starting with a row of 100,000 will immediately create 100,000
// empty rows.
//
// To avoid unnecessary garbage collection, fill columns from left to right.
func (t *Table) SetCell(row, column int, cell *TableCell) *Table {
	t.content.SetCell(row, column, cell)
	return t
}

// SetCellSimple calls SetCell() with the given text, left-aligned, in white.
func (t *Table) SetCellSimple(row, column int, text string) *Table {
	t.SetCell(row, column, NewTableCell(text))
	return t
}

// GetCell returns the contents of the cell at the specified position. A valid
// TableCell object is always returned but it will be uninitialized if the cell
// was not previously set. Such an uninitialized object will not automatically
// be inserted. Therefore, repeated calls to this function may return different
// pointers for uninitialized cells.
func (t *Table) GetCell(row, column int) *TableCell {
	cell := t.content.GetCell(row, column)
	if cell == nil {
		cell = &TableCell{}
	}
	return cell
}

// RemoveRow removes the row at the given position from the table. If there is
// no such row, this has no effect.
func (t *Table) RemoveRow(row int) *Table {
	t.content.RemoveRow(row)
	return t
}

// RemoveColumn removes the column at the given position from the table. If
// there is no such column, this has no effect.
func (t *Table) RemoveColumn(column int) *Table {
	t.content.RemoveColumn(column)
	return t
}

// InsertRow inserts a row before the row with the given index. Cells on the
// given row and below will be shifted to the bottom by one row. If "row" is
// equal or larger than the current number of rows, this function has no effect.
func (t *Table) InsertRow(row int) *Table {
	t.content.InsertRow(row)
	return t
}

// InsertColumn inserts a column before the column with the given index. Cells
// in the given column and to its right will be shifted to the right by one
// column. Rows that have fewer initialized cells than "column" will remain
// unchanged.
func (t *Table) InsertColumn(column int) *Table {
	t.content.InsertColumn(column)
	return t
}

// GetRowCount returns the number of rows in the table.
func (t *Table) GetRowCount() int {
	return t.content.GetRowCount()
}

// GetColumnCount returns the (maximum) number of columns in the table.
func (t *Table) GetColumnCount() int {
	return t.content.GetColumnCount()
}

// cellAt returns the row and column located at the given screen coordinates.
// Each returned value may be negative if there is no row and/or cell. This
// function will also process coordinates outside the table's inner rectangle so
// callers will need to check for bounds themselves.
func (t *Table) cellAt(x, y int) (row, column int) {
	rectX, rectY, _, _ := t.GetInnerRect()

	// Determine row as seen on screen.
	if t.borders {
		row = (y - rectY - 1) / 2
	} else {
		row = y - rectY
	}

	// Respect fixed rows and row offset.
	if row >= 0 {
		if row >= t.fixedRows {
			row += t.rowOffset
		}
		if row >= t.content.GetRowCount() {
			row = -1
		}
	}

	// Saerch for the clicked column.
	column = -1
	if x >= rectX {
		columnX := rectX
		if t.borders {
			columnX++
		}
		for index, width := range t.visibleColumnWidths {
			columnX += width + 1
			if x < columnX {
				column = t.visibleColumnIndices[index]
				break
			}
		}
	}

	return
}

// ScrollToBeginning scrolls the table to the beginning to that the top left
// corner of the table is shown. Note that this position may be corrected if
// there is a selection.
func (t *Table) ScrollToBeginning() *Table {
	t.trackEnd = false
	t.columnOffset = 0
	t.rowOffset = 0
	return t
}

// ScrollToEnd scrolls the table to the beginning to that the bottom left corner
// of the table is shown. Adding more rows to the table will cause it to
// automatically scroll with the new data. Note that this position may be
// corrected if there is a selection.
func (t *Table) ScrollToEnd() *Table {
	t.trackEnd = true
	t.columnOffset = 0
	t.rowOffset = t.content.GetRowCount()
	return t
}

// SetWrapSelection determines whether a selection wraps vertically or
// horizontally when moved. Vertically wrapping selections will jump from the
// last selectable row to the first selectable row and vice versa. Horizontally
// wrapping selections will jump from the last selectable column to the first
// selectable column (on the next selectable row) or from the first selectable
// column to the last selectable column (on the previous selectable row). If set
// to false, the selection is not moved when it is already on the first/last
// selectable row/column.
//
// The default is for both values to be false.
func (t *Table) SetWrapSelection(vertical, horizontal bool) *Table {
	t.wrapHorizontally = horizontal
	t.wrapVertically = vertical
	return t
}

// Draw draws this primitive onto the screen.
func (t *Table) Draw(screen tcell.Screen) {
	t.Box.DrawForSubclass(screen, t)

	// What's our available screen space?
	_, totalHeight := screen.Size()
	x, y, width, height := t.GetInnerRect()
	netWidth := width
	if t.borders {
		t.visibleRows = height / 2
		netWidth -= 2
	} else {
		t.visibleRows = height
	}

	// If this cell is not selectable, find the next one.
	rowCount, columnCount := t.content.GetRowCount(), t.content.GetColumnCount()
	if t.rowsSelectable || t.columnsSelectable {
		if t.selectedColumn < 0 {
			t.selectedColumn = 0
		}
		if t.selectedRow < 0 {
			t.selectedRow = 0
		}
		for t.selectedRow < rowCount {
			cell := t.content.GetCell(t.selectedRow, t.selectedColumn)
			if cell != nil && !cell.NotSelectable {
				break
			}
			t.selectedColumn++
			if t.selectedColumn > columnCount-1 {
				t.selectedColumn = 0
				t.selectedRow++
			}
		}
	}

	// Clamp row offsets if requested.
	defer func() {
		t.clampToSelection = false // Only once.
	}()
	if t.clampToSelection && t.rowsSelectable {
		if t.selectedRow >= t.fixedRows && t.selectedRow < t.fixedRows+t.rowOffset {
			t.rowOffset = t.selectedRow - t.fixedRows
			t.trackEnd = false
		}
		if t.borders {
			if t.selectedRow+1-t.rowOffset >= height/2 {
				t.rowOffset = t.selectedRow + 1 - height/2
				t.trackEnd = false
			}
		} else {
			if t.selectedRow+1-t.rowOffset >= height {
				t.rowOffset = t.selectedRow + 1 - height
				t.trackEnd = false
			}
		}
	}
	if t.rowOffset < 0 {
		t.rowOffset = 0
	}
	if t.borders {
		if rowCount-t.rowOffset < height/2 {
			t.trackEnd = true
		}
	} else {
		if rowCount-t.rowOffset < height {
			t.trackEnd = true
		}
	}
	if t.trackEnd {
		if t.borders {
			t.rowOffset = rowCount - height/2
		} else {
			t.rowOffset = rowCount - height
		}
	}
	if t.rowOffset < 0 {
		t.rowOffset = 0
	}

	// Avoid invalid column offsets.
	if t.columnOffset >= columnCount-t.fixedColumns {
		t.columnOffset = columnCount - t.fixedColumns - 1
	}
	if t.columnOffset < 0 {
		t.columnOffset = 0
	}

	// Determine the indices of the rows which fit on the screen.
	var (
		rows, allRows []int
		tableHeight   int
	)
	rowStep := 1
	if t.borders {
		rowStep = 2 // With borders, every table row takes two screen rows.
	}
	if t.evaluateAllRows {
		allRows = make([]int, rowCount)
		for row := 0; row < rowCount; row++ {
			allRows[row] = row
		}
	}
	indexRow := func(row int) bool { // Determine if this row is visible, store its index.
		if tableHeight >= height {
			return false
		}
		rows = append(rows, row)
		tableHeight += rowStep
		return true
	}
	for row := 0; row < t.fixedRows && row < rowCount; row++ { // Do the fixed rows first.
		if !indexRow(row) {
			break
		}
	}
	for row := t.fixedRows + t.rowOffset; row < rowCount; row++ { // Then the remaining rows.
		if !indexRow(row) {
			break
		}
	}

	// Determine the columns' indices, widths, and expansion values that fit on
	// the screen.
	var (
		tableWidth, expansionTotal  int
		columns, widths, expansions []int
	)
	includesSelection := !t.clampToSelection || !t.columnsSelectable

	// Helper function that evaluates one column. Returns true if the column
	// didn't fit at all.
	indexColumn := func(column int) bool {
		if netWidth == 0 || tableWidth >= netWidth {
			return true
		}

		var maxWidth, expansion int
		evaluationRows := rows
		if t.evaluateAllRows {
			evaluationRows = allRows
		}
		for _, row := range evaluationRows {
			if cell := t.content.GetCell(row, column); cell != nil {
				_, _, _, _, _, _, cellWidth := decomposeString(cell.Text, true, false)
				if cell.MaxWidth > 0 && cell.MaxWidth < cellWidth {
					cellWidth = cell.MaxWidth
				}
				if cellWidth > maxWidth {
					maxWidth = cellWidth
				}
				if cell.Expansion > expansion {
					expansion = cell.Expansion
				}
			}
		}
		clampedMaxWidth := maxWidth
		if tableWidth+maxWidth > netWidth {
			clampedMaxWidth = netWidth - tableWidth
		}
		columns = append(columns, column)
		widths = append(widths, clampedMaxWidth)
		expansions = append(expansions, expansion)
		tableWidth += clampedMaxWidth + 1
		expansionTotal += expansion
		if t.columnsSelectable && t.clampToSelection && column == t.selectedColumn {
			// We want selections to appear fully.
			includesSelection = clampedMaxWidth == maxWidth
		}

		return false
	}

	// Helper function that evaluates multiple columns, starting at "start" and
	// at most ending at "maxEnd". Returns first column not included anymore (or
	// -1 if all are included).
	indexColumns := func(start, maxEnd int) int {
		if start == maxEnd {
			return -1
		}

		if start < maxEnd {
			// Forward-evaluate columns.
			for column := start; column < maxEnd; column++ {
				if indexColumn(column) {
					return column
				}
			}
			return -1
		}

		// Backward-evaluate columns.
		startLen := len(columns)
		defer func() {
			// Becaue we went backwards, we must reverse the partial slices.
			for i, j := startLen, len(columns)-1; i < j; i, j = i+1, j-1 {
				columns[i], columns[j] = columns[j], columns[i]
				widths[i], widths[j] = widths[j], widths[i]
				expansions[i], expansions[j] = expansions[j], expansions[i]
			}
		}()
		for column := start; column >= maxEnd; column-- {
			if indexColumn(column) {
				return column
			}
		}
		return -1
	}

	// Reset the table to only its fixed columns.
	var fixedTableWidth, fixedExpansionTotal int
	resetColumns := func() {
		tableWidth = fixedTableWidth
		expansionTotal = fixedExpansionTotal
		columns = columns[:t.fixedColumns]
		widths = widths[:t.fixedColumns]
		expansions = expansions[:t.fixedColumns]
	}

	// Add fixed columns.
	if indexColumns(0, t.fixedColumns) < 0 {
		fixedTableWidth = tableWidth
		fixedExpansionTotal = expansionTotal

		// Add unclamped columns.
		if column := indexColumns(t.fixedColumns+t.columnOffset, columnCount); !includesSelection || column < 0 && t.columnOffset > 0 {
			// Offset is not optimal. Try again.
			if !includesSelection {
				// Clamp to selection.
				resetColumns()
				if t.selectedColumn <= t.fixedColumns+t.columnOffset {
					// It's on the left. Start with the selection.
					t.columnOffset = t.selectedColumn - t.fixedColumns
					indexColumns(t.fixedColumns+t.columnOffset, columnCount)
				} else {
					// It's on the right. End with the selection.
					if column := indexColumns(t.selectedColumn, t.fixedColumns); column >= 0 {
						t.columnOffset = column + 1 - t.fixedColumns
					} else {
						t.columnOffset = 0
					}
				}
			} else if tableWidth < netWidth {
				// Don't waste space. Try to fit as much on screen as possible.
				resetColumns()
				if column := indexColumns(columnCount-1, t.fixedColumns); column >= 0 {
					t.columnOffset = column + 1 - t.fixedColumns
				} else {
					t.columnOffset = 0
				}
			}
		}
	}

	// If we have space left, distribute it.
	if tableWidth < netWidth {
		toDistribute := netWidth - tableWidth
		for index, expansion := range expansions {
			if expansionTotal <= 0 {
				break
			}
			expWidth := toDistribute * expansion / expansionTotal
			widths[index] += expWidth
			toDistribute -= expWidth
			expansionTotal -= expansion
		}
	}

	// Helper function which draws border runes.
	borderStyle := tcell.StyleDefault.Background(t.backgroundColor).Foreground(t.bordersColor)
	drawBorder := func(colX, rowY int, ch rune) {
		screen.SetContent(x+colX, y+rowY, ch, nil, borderStyle)
	}

	// Draw the cells (and borders).
	var columnX int
	if t.borders {
		columnX++
	}
	for columnIndex, column := range columns {
		columnWidth := widths[columnIndex]
		for rowY, row := range rows {
			if t.borders {
				// Draw borders.
				rowY *= 2
				for pos := 0; pos < columnWidth && columnX+pos < width; pos++ {
					drawBorder(columnX+pos, rowY, Borders.Horizontal)
				}
				ch := Borders.Cross
				if row == 0 {
					if column == 0 {
						ch = Borders.TopLeft
					} else {
						ch = Borders.TopT
					}
				} else if column == 0 {
					ch = Borders.LeftT
				}
				drawBorder(columnX-1, rowY, ch)
				rowY++
				if rowY >= height || y+rowY >= totalHeight {
					break // No space for the text anymore.
				}
				drawBorder(columnX-1, rowY, Borders.Vertical)
			} else if column < columnCount-1 {
				// Draw separator.
				drawBorder(columnX+columnWidth, rowY, t.separator)
			}

			// Get the cell.
			cell := t.content.GetCell(row, column)
			if cell == nil {
				continue
			}

			// Draw text.
			finalWidth := columnWidth
			if columnX+columnWidth >= width {
				finalWidth = width - columnX
			}
			cell.x, cell.y, cell.width = x+columnX, y+rowY, finalWidth
			_, printed, _, _ := printWithStyle(screen, cell.Text, x+columnX, y+rowY, 0, finalWidth, cell.Align, tcell.StyleDefault.Foreground(cell.Color).Attributes(cell.Attributes), true)
			if TaggedStringWidth(cell.Text)-printed > 0 && printed > 0 {
				_, _, style, _ := screen.GetContent(x+columnX+finalWidth-1, y+rowY)
				printWithStyle(screen, string(SemigraphicsHorizontalEllipsis), x+columnX+finalWidth-1, y+rowY, 0, 1, AlignLeft, style, false)
			}
		}

		// Draw bottom border.
		if rowY := 2 * len(rows); t.borders && rowY > 0 && rowY < height {
			for pos := 0; pos < columnWidth && columnX+1+pos < width; pos++ {
				drawBorder(columnX+pos, rowY, Borders.Horizontal)
			}
			ch := Borders.Cross
			if rows[len(rows)-1] == rowCount-1 {
				if column == 0 {
					ch = Borders.BottomLeft
				} else {
					ch = Borders.BottomT
				}
			} else if column == 0 {
				ch = Borders.BottomLeft
			}
			drawBorder(columnX-1, rowY, ch)
		}

		columnX += columnWidth + 1
	}

	// Draw right border.
	columnX--
	if t.borders && len(rows) > 0 && len(columns) > 0 && columnX < width {
		lastColumn := columns[len(columns)-1] == columnCount-1
		for rowY := range rows {
			rowY *= 2
			if rowY+1 < height {
				drawBorder(columnX, rowY+1, Borders.Vertical)
			}
			ch := Borders.Cross
			if rowY == 0 {
				if lastColumn {
					ch = Borders.TopRight
				} else {
					ch = Borders.TopT
				}
			} else if lastColumn {
				ch = Borders.RightT
			}
			drawBorder(columnX, rowY, ch)
		}
		if rowY := 2 * len(rows); rowY < height {
			ch := Borders.BottomT
			if lastColumn {
				ch = Borders.BottomRight
			}
			drawBorder(columnX, rowY, ch)
		}
	}

	// Helper function which colors the background of a box.
	// backgroundTransparent == true => Don't modify background color (when invert == false).
	// textTransparent == true => Don't modify text color (when invert == false).
	// attr == 0 => Don't change attributes.
	// invert == true => Ignore attr, set text to backgroundColor or t.backgroundColor;
	//                   set background to textColor.
	colorBackground := func(fromX, fromY, w, h int, backgroundColor, textColor tcell.Color, backgroundTransparent, textTransparent bool, attr tcell.AttrMask, invert bool) {
		for by := 0; by < h && fromY+by < y+height; by++ {
			for bx := 0; bx < w && fromX+bx < x+width; bx++ {
				m, c, style, _ := screen.GetContent(fromX+bx, fromY+by)
				fg, bg, a := style.Decompose()
				if invert {
					style = style.Background(textColor).Foreground(backgroundColor)
				} else {
					if !backgroundTransparent {
						bg = backgroundColor
					}
					if !textTransparent {
						fg = textColor
					}
					if attr != 0 {
						a = attr
					}
					style = style.Background(bg).Foreground(fg).Attributes(a)
				}
				screen.SetContent(fromX+bx, fromY+by, m, c, style)
			}
		}
	}

	// Color the cell backgrounds. To avoid undesirable artefacts, we combine
	// the drawing of a cell by background color, selected cells last.
	type cellInfo struct {
		x, y, w, h int
		cell       *TableCell
		selected   bool
	}
	cellsByBackgroundColor := make(map[tcell.Color][]*cellInfo)
	var backgroundColors []tcell.Color
	for rowY, row := range rows {
		columnX := 0
		rowSelected := t.rowsSelectable && !t.columnsSelectable && row == t.selectedRow
		for columnIndex, column := range columns {
			columnWidth := widths[columnIndex]
			cell := t.content.GetCell(row, column)
			if cell == nil {
				continue
			}
			bx, by, bw, bh := x+columnX, y+rowY, columnWidth+1, 1
			if t.borders {
				by = y + rowY*2
				bw++
				bh = 3
			}
			columnSelected := t.columnsSelectable && !t.rowsSelectable && column == t.selectedColumn
			cellSelected := !cell.NotSelectable && (columnSelected || rowSelected || t.rowsSelectable && t.columnsSelectable && column == t.selectedColumn && row == t.selectedRow)
			entries, ok := cellsByBackgroundColor[cell.BackgroundColor]
			cellsByBackgroundColor[cell.BackgroundColor] = append(entries, &cellInfo{
				x:        bx,
				y:        by,
				w:        bw,
				h:        bh,
				cell:     cell,
				selected: cellSelected,
			})
			if !ok {
				backgroundColors = append(backgroundColors, cell.BackgroundColor)
			}
			columnX += columnWidth + 1
		}
	}
	sort.Slice(backgroundColors, func(i int, j int) bool {
		// Draw brightest colors last (i.e. on top).
		r, g, b := backgroundColors[i].RGB()
		c := colorful.Color{R: float64(r) / 255, G: float64(g) / 255, B: float64(b) / 255}
		_, _, li := c.Hcl()
		r, g, b = backgroundColors[j].RGB()
		c = colorful.Color{R: float64(r) / 255, G: float64(g) / 255, B: float64(b) / 255}
		_, _, lj := c.Hcl()
		return li < lj
	})
	selFg, selBg, selAttr := t.selectedStyle.Decompose()
	for _, bgColor := range backgroundColors {
		entries := cellsByBackgroundColor[bgColor]
		for _, info := range entries {
			if info.selected {
				if t.selectedStyle != (tcell.Style{}) {
					defer colorBackground(info.x, info.y, info.w, info.h, selBg, selFg, false, false, selAttr, false)
				} else {
					defer colorBackground(info.x, info.y, info.w, info.h, bgColor, info.cell.Color, false, false, 0, true)
				}
			} else {
				colorBackground(info.x, info.y, info.w, info.h, bgColor, info.cell.Color, info.cell.Transparent, true, 0, false)
			}
		}
	}

	// Remember column infos.
	t.visibleColumnIndices, t.visibleColumnWidths = columns, widths
}

// InputHandler returns the handler for this primitive.
func (t *Table) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
	return t.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
		key := event.Key()

		if (!t.rowsSelectable && !t.columnsSelectable && key == tcell.KeyEnter) ||
			key == tcell.KeyEscape ||
			key == tcell.KeyTab ||
			key == tcell.KeyBacktab {
			if t.done != nil {
				t.done(key)
			}
			return
		}

		// Movement functions.
		previouslySelectedRow, previouslySelectedColumn := t.selectedRow, t.selectedColumn
		lastColumn := t.content.GetColumnCount() - 1
		rowCount := t.content.GetRowCount()
		if rowCount == 0 {
			return // No movement on empty tables.
		}
		var (
			previous = func() {
				startRow := t.selectedRow
				startColumn := t.selectedColumn
				for {
					cell := t.content.GetCell(t.selectedRow, t.selectedColumn)
					if cell != nil && !cell.NotSelectable {
						return
					}
					t.selectedColumn--
					if t.selectedColumn < 0 {
						t.selectedColumn = lastColumn
						t.selectedRow--
						if t.selectedRow < 0 {
							t.selectedRow = rowCount - 1
						}
					}
					if t.selectedColumn == startColumn && t.selectedRow == startRow {
						t.selectedColumn = 0
						t.selectedRow = 0
						return
					}
				}
			}

			next = func() {
				startRow := t.selectedRow
				startColumn := t.selectedColumn
				for {
					if t.selectedColumn <= lastColumn {
						cell := t.content.GetCell(t.selectedRow, t.selectedColumn)
						if cell != nil && !cell.NotSelectable {
							return
						}
					}
					if t.selectedColumn >= lastColumn {
						t.selectedColumn = 0
						if t.selectedRow >= rowCount-1 {
							t.selectedRow = 0
						} else {
							t.selectedRow++
						}
					} else {
						t.selectedColumn++
					}
					if t.selectedColumn == startColumn && t.selectedRow == startRow {
						t.selectedColumn = 0
						t.selectedRow = 0
						return
					}
				}
			}

			home = func() {
				if t.rowsSelectable {
					t.selectedRow = 0
					t.selectedColumn = 0
					t.clampToSelection = true
					next()
				} else {
					t.trackEnd = false
					t.rowOffset = 0
					t.columnOffset = 0
				}
			}

			end = func() {
				if t.rowsSelectable {
					t.selectedRow = rowCount - 1
					t.selectedColumn = lastColumn
					t.clampToSelection = true
					previous()
				} else {
					t.trackEnd = true
					t.columnOffset = 0
				}
			}

			down = func() {
				if t.rowsSelectable {
					startRow := t.selectedRow
					t.selectedRow++
					if t.selectedRow >= rowCount {
						t.selectedRow = 0
					}
					t.clampToSelection = true
					next()
					if !t.wrapVertically && t.selectedRow < startRow {
						t.selectedRow = rowCount - 1
						t.selectedColumn = lastColumn
						previous()
					}
				} else {
					t.rowOffset++
				}
			}

			up = func() {
				if t.rowsSelectable {
					startRow := t.selectedRow
					t.selectedRow--
					if t.selectedRow < 0 {
						t.selectedRow = rowCount - 1
					}
					t.clampToSelection = true
					previous()
					if !t.wrapVertically && t.selectedRow > startRow {
						t.selectedRow = 0
						t.selectedColumn = 0
						next()
					}
				} else {
					t.trackEnd = false
					t.rowOffset--
				}
			}

			left = func() {
				if t.columnsSelectable {
					startRow := t.selectedRow
					startColumn := t.selectedColumn
					t.selectedColumn--
					if t.selectedColumn < 0 {
						t.selectedColumn = lastColumn
						t.selectedRow--
						if t.selectedRow < 0 {
							t.selectedRow = rowCount - 1
						}
					}
					t.clampToSelection = true
					previous()
					if !t.wrapHorizontally && (t.selectedRow != startRow || t.selectedColumn > startColumn) ||
						!t.wrapVertically && t.selectedRow > startRow {
						t.selectedRow = startRow
						t.selectedColumn = startColumn
					}
				} else {
					t.columnOffset--
				}
			}

			right = func() {
				if t.columnsSelectable {
					startRow := t.selectedRow
					startColumn := t.selectedColumn
					t.selectedColumn++
					t.clampToSelection = true
					next()
					if !t.wrapHorizontally && (t.selectedRow != startRow || t.selectedColumn < startColumn) ||
						!t.wrapVertically && t.selectedRow < startRow {
						t.selectedRow = startRow
						t.selectedColumn = startColumn
					}
				} else {
					t.columnOffset++
				}
			}

			pageDown = func() {
				offsetAmount := t.visibleRows - t.fixedRows
				if offsetAmount < 0 {
					offsetAmount = 0
				}

				if t.rowsSelectable {
					startRow := t.selectedRow
					t.selectedRow += offsetAmount
					if t.selectedRow >= rowCount {
						t.selectedRow = rowCount - 1
					}
					t.clampToSelection = true
					next()
					if !t.wrapVertically && t.selectedRow < startRow {
						t.selectedRow = rowCount - 1
						t.selectedColumn = lastColumn
						previous()
					}
				} else {
					t.rowOffset += offsetAmount
				}
			}

			pageUp = func() {
				offsetAmount := t.visibleRows - t.fixedRows
				if offsetAmount < 0 {
					offsetAmount = 0
				}

				if t.rowsSelectable {
					startRow := t.selectedRow
					t.selectedRow -= offsetAmount
					if t.selectedRow < 0 {
						t.selectedRow = 0
					}
					t.clampToSelection = true
					previous()
					if !t.wrapVertically && t.selectedRow > startRow {
						t.selectedRow = 0
						t.selectedColumn = 0
						next()
					}
				} else {
					t.trackEnd = false
					t.rowOffset -= offsetAmount
				}
			}
		)

		switch key {
		case tcell.KeyRune:
			switch event.Rune() {
			case 'g':
				home()
			case 'G':
				end()
			case 'j':
				down()
			case 'k':
				up()
			case 'h':
				left()
			case 'l':
				right()
			}
		case tcell.KeyHome:
			home()
		case tcell.KeyEnd:
			end()
		case tcell.KeyUp:
			up()
		case tcell.KeyDown:
			down()
		case tcell.KeyLeft:
			left()
		case tcell.KeyRight:
			right()
		case tcell.KeyPgDn, tcell.KeyCtrlF:
			pageDown()
		case tcell.KeyPgUp, tcell.KeyCtrlB:
			pageUp()
		case tcell.KeyEnter:
			if (t.rowsSelectable || t.columnsSelectable) && t.selected != nil {
				t.selected(t.selectedRow, t.selectedColumn)
			}
		}

		// If the selection has changed, notify the handler.
		if t.selectionChanged != nil &&
			(t.rowsSelectable && previouslySelectedRow != t.selectedRow ||
				t.columnsSelectable && previouslySelectedColumn != t.selectedColumn) {
			t.selectionChanged(t.selectedRow, t.selectedColumn)
		}
	})
}

// MouseHandler returns the mouse handler for this primitive.
func (t *Table) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
	return t.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
		x, y := event.Position()
		if !t.InRect(x, y) {
			return false, nil
		}

		switch action {
		case MouseLeftClick:
			selectEvent := true
			row, column := t.cellAt(x, y)
			cell := t.content.GetCell(row, column)
			if cell != nil && cell.Clicked != nil {
				if noSelect := cell.Clicked(); noSelect {
					selectEvent = false
				}
			}
			if selectEvent && (t.rowsSelectable || t.columnsSelectable) {
				t.Select(row, column)
			}
			setFocus(t)
			consumed = true
		case MouseScrollUp:
			t.trackEnd = false
			t.rowOffset--
			consumed = true
		case MouseScrollDown:
			t.rowOffset++
			consumed = true
		}

		return
	})
}