Gumby.ListBox

0.0.1.0

Gumby.ListBox.psm1

using module ScrollView

class LBItemBase {
    [string] Name() { throw "abstract" }
    [object] Value() { throw "abstract" }
    [void] OnSelected() {}
    [void] OnDeselected() {}
}

class StringLBItem : LBItemBase {
    StringLBItem([string] $value) {
        $this._value = $value
    }

    [string] Name() { return $this._value }
    [string] Value() { return $this._value }

    hidden [string] $_value
}

class ListBox : ScrollView {

    ListBox(
        [int] $left,
        [int] $top,
        [int] $width,
        [int] $height,
        [System.ConsoleColor] $foregroundColor = $Global:Host.UI.RawUI.BackgroundColor,
        [System.ConsoleColor] $backgroundColor = $Global:Host.UI.RawUI.ForegroundColor
    ) : base($left, $top, $width, $height, $foregroundColor, $backgroundColor) {
    }

    ListBox(
        [System.Collections.IEnumerable] $items,
        [System.Reflection.TypeInfo] $lbItemType,
        [int] $left,
        [int] $top,
        [int] $width,
        [int] $height,
        [System.ConsoleColor] $foregroundColor = $Global:Host.UI.RawUI.BackgroundColor,
        [System.ConsoleColor] $backgroundColor = $Global:Host.UI.RawUI.ForegroundColor
    ) : base($left, $top, $width, $height, $foregroundColor, $backgroundColor) {

        $lbItems = [System.Collections.Generic.List`1[LBItemBase]]::new()
        foreach ($item in $items) {
            $lbItems.Add($lbItemType::new($item)) | Out-Null
        }

        $this.InitializeItems($lbItems)
    }

    hidden [void] InitializeItems([System.Collections.Generic.IEnumerable`1[LBItemBase]] $lbItems) {
        foreach ($lbItem in $lbItems) {
            [void]($this._items.Add($lbItem))
            $this.AddLine($this.GetItemLabel($lbItem), $this.ForegroundColor(), $this.BackgroundColor())
        }

        if ($this.ItemCount() -gt 0) { $this.SelectItem(0) }
    }

    [int] ItemCount() { return $this._items.Count }

    [void] AddItem([object] $item) {
        [void]($this._items.Add($item))
        $this.AddLine($this.GetItemLabel($item), $this.ForegroundColor(), $this.BackgroundColor())
    }

    [void] InsertItem([int] $index, [object] $item) {
        if ($this._selectedIndex -ne -1) {
            if ($index -le $this._selectedIndex) { ++$this._selectedIndex }
        }

        $this._items.Insert($index, $item)
        $this.InsertLine($index, $this.GetItemLabel($item), $this.ForegroundColor(), $this.BackgroundColor())
    }

    [LBItemBase] GetItem([int] $index) { return $this._items[$index] }

    [void] RemoveItem([int] $index) {
        if ($this._selectedIndex -ne -1) {
            if ($index -lt $this._selectedIndex) {
                --$this._selectedIndex
            } elseif ($index -eq $this._selectedIndex) { 
                $this._selectedIndex = -1
            }
        }

        $this._items.RemoveAt($index)
        $this.RemoveLine($index)
    }

    [void] SelectItem([int] $index) {
        if ($index -ge 0) {
            if ($index -ne $this._selectedIndex) {

                if ($this._selectedIndex -ge 0) {
                    # deselect currently selected item
                    $this.GetLine($this._selectedIndex).ForegroundColor = $this.ForegroundColor()
                    $this.GetLine($this._selectedIndex).BackgroundColor = $this.BackgroundColor()

                    $this._items[$this._selectedIndex].OnDeselected()
                }
    
                # select new item
                $this.GetLine($index).ForegroundColor = $this.BackgroundColor()
                $this.GetLine($index).BackgroundColor = $this.ForegroundColor()
    
                $this._selectedIndex = $index

                $this._items[$this._selectedIndex].OnSelected()
            }
        } else {
            # removing selection

            if ($this._selectedIndex -ge 0) {
                # deselect currently selected item
                $this.GetLine($this._selectedIndex).ForegroundColor = $this.ForegroundColor()
                $this.GetLine($this._selectedIndex).BackgroundColor = $this.BackgroundColor()

                $this._items[$this._selectedIndex].OnDeselected()
            }

            $this._selectedIndex = -1 # normalizing to -1
        }
    }

    [int] SelectedIndex() {
        return $this._selectedIndex
    }

    [LBItemBase] SelectedItem() {
        return $this._items[$this._selectedIndex]
    }

    hidden DrawClientArea() {
        ([ScrollView]$this).DrawClientArea()
        $si = if ($this._items.Count -gt 0) { $this._selectedIndex + 1 } else { 0 }
        $this.WriteStatusBar("$si/$($this._items.Count)")
    }

    hidden [void] OnKey([System.ConsoleKeyInfo] $key) {
        #[Log]::Comment("SVListBox.OnKey: Key=$($key.Key), Modifiers=$($key.Modifiers)")

        switch ($key.Key) {
            ([ConsoleKey]::DownArrow) { $this.MoveSelectionDown() }
            ([ConsoleKey]::UpArrow) { $this.MoveSelectionUp() }
            default { ([ScrollView]$this).OnKey($key) }
        }
    }

    hidden [void] MoveSelectionDown() {
        if ($this._items.Count -eq 0) {
            # empty list
            return
        }

        if ($this._selectedIndex -eq ($this._items.Count - 1)) {
            # at end of list, no change
            return
        }

        if (($this._selectedIndex - $this.FirstRowInView) -ge ($this.ClientHeight() - 1)) {
            # last line in view is selected, scroll up one line

            $this.ScrollAreaVertically(0, $this.ClientHeight() - 2, -1)
            ++$this.FirstRowInView
        }

        $previouslySelectedIndex = $this._selectedIndex
        $this.SelectItem($this._selectedIndex + 1)
        $this.DrawLine($this._selectedIndex)
        $this.DrawLine($previouslySelectedIndex)

        $this.WriteStatusBar("$($this._selectedIndex + 1)/$($this._items.Count)")
    }

    hidden [void] MoveSelectionUp() {
        if ($this._selectedIndex -eq 0) {
            # at start of list, no change
            # also handles empty list
            return
        }

        if ($this._selectedIndex -eq $this.FirstRowInView) {
            # first line in view is selected, scroll down one line

            $this.ScrollAreaVertically(1, $this.ClientHeight() - 2, 1)
            --$this.FirstRowInView
        }

        $previouslySelectedIndex = $this._selectedIndex
        $this.SelectItem($this._selectedIndex - 1)
        $this.DrawLine($this._selectedIndex)
        $this.DrawLine($previouslySelectedIndex)

        $this.WriteStatusBar("$($this._selectedIndex + 1)/$($this._items.Count)")
    }

    hidden [string] GetItemLabel([object]$item) {
        return $item.Name()
    }

    hidden [System.Collections.ICollection] $_items = ([System.Collections.ArrayList]::new())
    hidden [int] $_selectedIndex = -1
}