package main
 
import (
	"sync"
 
	"github.com/gdamore/tcell/v2"
	"code.rocketnine.space/tslocum/cview"
)
 
// panel represents a single panel of a Panels object.
type panel struct {
	Name    string    // The panel's name.
	Item    cview.Primitive // The panel's cview.Primitive.
	Resize  bool      // Whether or not to resize the panel when it is drawn.
	Visible bool      // Whether or not this panel is visible.
}
 
// Panels is a container for other cview.Primitives often used as the application's
// root cview.Primitive. It allows to easily switch the visibility of the contained
// cview.Primitives.
type Panels struct {
	*cview.Box
 
	// The contained panels. (Visible) panels are drawn from back to front.
	panels []*panel
 
	// We keep a reference to the function which allows us to set the focus to
	// a newly visible panel.
	setFocus func(p cview.Primitive)
 
	// An optional handler which is called whenever the visibility or the order of
	// panels changes.
	changed func()
 
	sync.RWMutex
}
 
// NewPanels returns a new Panels object.
func NewPanels() *Panels {
	p := &Panels{
		Box: cview.NewBox(),
	}
	//p.focus = p
	return p
}
 
// SetChangedFunc sets a handler which is called whenever the visibility or the
// order of any visible panels changes. This can be used to redraw the panels.
func (p *Panels) SetChangedFunc(handler func()) {
	p.Lock()
	defer p.Unlock()
 
	p.changed = handler
}
 
// GetPanelCount returns the number of panels currently stored in this object.
func (p *Panels) GetPanelCount() int {
	p.RLock()
	defer p.RUnlock()
 
	return len(p.panels)
}
 
// AddPanel adds a new panel with the given name and cview.Primitive. If there was
// previously a panel with the same name, it is overwritten. Leaving the name
// empty may cause conflicts in other functions so always specify a non-empty
// name.
//
// Visible panels will be drawn in the order they were added (unless that order
// was changed in one of the other functions). If "resize" is set to true, the
// cview.Primitive will be set to the size available to the Panels cview.Primitive whenever
// the panels are drawn.
func (p *Panels) AddPanel(name string, item cview.Primitive, resize, visible bool) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	var added bool
	for i, pg := range p.panels {
		if pg.Name == name {
			p.panels[i] = &panel{Item: item, Name: name, Resize: resize, Visible: visible}
			added = true
			break
		}
	}
	if !added {
		p.panels = append(p.panels, &panel{Item: item, Name: name, Resize: resize, Visible: visible})
	}
	if p.changed != nil {
		p.Unlock()
		p.changed()
		p.Lock()
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// RemovePanel removes the panel with the given name. If that panel was the only
// visible panel, visibility is assigned to the last panel.
func (p *Panels) RemovePanel(name string) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	var isVisible bool
	for index, panel := range p.panels {
		if panel.Name == name {
			isVisible = panel.Visible
			p.panels = append(p.panels[:index], p.panels[index+1:]...)
			if panel.Visible && p.changed != nil {
				p.Unlock()
				p.changed()
				p.Lock()
			}
			break
		}
	}
	if isVisible {
		for index, panel := range p.panels {
			if index < len(p.panels)-1 {
				if panel.Visible {
					break // There is a remaining visible panel.
				}
			} else {
				panel.Visible = true // We need at least one visible panel.
			}
		}
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// HasPanel returns true if a panel with the given name exists in this object.
func (p *Panels) HasPanel(name string) bool {
	p.RLock()
	defer p.RUnlock()
 
	for _, panel := range p.panels {
		if panel.Name == name {
			return true
		}
	}
	return false
}
 
// ShowPanel sets a panel's visibility to "true" (in addition to any other panels
// which are already visible).
func (p *Panels) ShowPanel(name string) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	for _, panel := range p.panels {
		if panel.Name == name {
			panel.Visible = true
			if p.changed != nil {
				p.Unlock()
				p.changed()
				p.Lock()
			}
			break
		}
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// HidePanel sets a panel's visibility to "false".
func (p *Panels) HidePanel(name string) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	for _, panel := range p.panels {
		if panel.Name == name {
			panel.Visible = false
			if p.changed != nil {
				p.Unlock()
				p.changed()
				p.Lock()
			}
			break
		}
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// SetCurrentPanel sets a panel's visibility to "true" and all other panels'
// visibility to "false".
func (p *Panels) SetCurrentPanel(name string) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	for _, panel := range p.panels {
		if panel.Name == name {
			panel.Visible = true
		} else {
			panel.Visible = false
		}
	}
	if p.changed != nil {
		p.Unlock()
		p.changed()
		p.Lock()
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// SendToFront changes the order of the panels such that the panel with the given
// name comes last, causing it to be drawn last with the next update (if
// visible).
func (p *Panels) SendToFront(name string) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	for index, panel := range p.panels {
		if panel.Name == name {
			if index < len(p.panels)-1 {
				p.panels = append(append(p.panels[:index], p.panels[index+1:]...), panel)
			}
			if panel.Visible && p.changed != nil {
				p.Unlock()
				p.changed()
				p.Lock()
			}
			break
		}
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// SendToBack changes the order of the panels such that the panel with the given
// name comes first, causing it to be drawn first with the next update (if
// visible).
func (p *Panels) SendToBack(name string) {
	hasFocus := p.HasFocus()
 
	p.Lock()
	defer p.Unlock()
 
	for index, pg := range p.panels {
		if pg.Name == name {
			if index > 0 {
				p.panels = append(append([]*panel{pg}, p.panels[:index]...), p.panels[index+1:]...)
			}
			if pg.Visible && p.changed != nil {
				p.Unlock()
				p.changed()
				p.Lock()
			}
			break
		}
	}
	if hasFocus {
		p.Unlock()
		p.Focus(p.setFocus)
		p.Lock()
	}
}
 
// GetFrontPanel returns the front-most visible panel. If there are no visible
// panels, ("", nil) is returned.
func (p *Panels) GetFrontPanel() (name string, item cview.Primitive) {
	p.RLock()
	defer p.RUnlock()
 
	for index := len(p.panels) - 1; index >= 0; index-- {
		if p.panels[index].Visible {
			return p.panels[index].Name, p.panels[index].Item
		}
	}
	return
}
 
// HasFocus returns whether or not this cview.Primitive has focus.
func (p *Panels) HasFocus() bool {
	p.RLock()
	defer p.RUnlock()
 
	for _, panel := range p.panels {
		if panel.Item.GetFocusable().HasFocus() {
			return true
		}
	}
	return false
}
 
// Focus is called by the application when the cview.Primitive receives focus.
func (p *Panels) Focus(delegate func(p cview.Primitive)) {
	p.Lock()
	defer p.Unlock()
 
	if delegate == nil {
		return // We cannot delegate so we cannot focus.
	}
	p.setFocus = delegate
	var topItem cview.Primitive
	for _, panel := range p.panels {
		if panel.Visible {
			topItem = panel.Item
		}
	}
	if topItem != nil {
		p.Unlock()
		delegate(topItem)
		p.Lock()
	}
}
 
// Draw draws this cview.Primitive onto the screen.
func (p *Panels) Draw(screen tcell.Screen) {
	if !p.GetVisible() {
		return
	}
 
	p.Box.Draw(screen)
 
	p.Lock()
	defer p.Unlock()
 
	x, y, width, height := p.GetInnerRect()
 
	for _, panel := range p.panels {
		if !panel.Visible {
			continue
		}
		if panel.Resize {
			panel.Item.SetRect(x, y, width, height)
		}
		panel.Item.Draw(screen)
	}
}
 
// MouseHandler returns the mouse handler for this cview.Primitive.
func (p *Panels) MouseHandler() func(action cview.MouseAction, event *tcell.EventMouse, setFocus func(p cview.Primitive)) (consumed bool, capture cview.Primitive) {
	return p.WrapMouseHandler(func(action cview.MouseAction, event *tcell.EventMouse, setFocus func(p cview.Primitive)) (consumed bool, capture cview.Primitive) {
		if !p.InRect(event.Position()) {
			return false, nil
		}
 
		// Pass mouse events along to the last visible panel item that takes it.
		for index := len(p.panels) - 1; index >= 0; index-- {
			panel := p.panels[index]
			if panel.Visible {
				consumed, capture = panel.Item.MouseHandler()(action, event, setFocus)
				if consumed {
					return
				}
			}
		}
 
		return
	})
}
 
// Support backwards compatibility with Pages.
type page = panel
 
// Pages is a wrapper around Panels.
//
// Deprecated: This type is provided for backwards compatibility.
// Developers should use Panels instead.
type Pages struct {
	*Panels
}
 
// NewPages returns a new Panels object.
//
// Deprecated: This function is provided for backwards compatibility.
// Developers should use NewPanels instead.
func NewPages() *Pages {
	return &Pages{NewPanels()}
}
 
// GetPageCount returns the number of panels currently stored in this object.
func (p *Pages) GetPageCount() int {
	return p.GetPanelCount()
}
 
// AddPage adds a new panel with the given name and cview.Primitive.
func (p *Pages) AddPage(name string, item cview.Primitive, resize, visible bool) {
	p.AddPanel(name, item, resize, visible)
}
 
// AddAndSwitchToPage calls Add(), then SwitchTo() on that newly added panel.
func (p *Pages) AddAndSwitchToPage(name string, item cview.Primitive, resize bool) {
	p.AddPanel(name, item, resize, true)
	p.SetCurrentPanel(name)
}
 
// RemovePage removes the panel with the given name.
func (p *Pages) RemovePage(name string) {
	p.RemovePanel(name)
}
 
// HasPage returns true if a panel with the given name exists in this object.
func (p *Pages) HasPage(name string) bool {
	return p.HasPanel(name)
}
 
// ShowPage sets a panel's visibility to "true".
func (p *Pages) ShowPage(name string) {
	p.ShowPanel(name)
}
 
// HidePage sets a panel's visibility to "false".
func (p *Pages) HidePage(name string) {
	p.HidePanel(name)
}
 
// SwitchToPage sets a panel's visibility to "true" and all other panels'
// visibility to "false".
func (p *Pages) SwitchToPage(name string) {
	p.SetCurrentPanel(name)
}
 
// GetFrontPage returns the front-most visible panel.
func (p *Pages) GetFrontPage() (name string, item cview.Primitive) {
	return p.GetFrontPanel()
}