/
paginator.go
202 lines (183 loc) · 4.35 KB
/
paginator.go
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// Package paginator provides a Bubble Tea package for calulating pagination
// and rendering pagination info. Note that this package does not render actual
// pages: it's purely for handling keystrokes related to pagination, and
// rendering pagination status.
package paginator
import (
"fmt"
tea "github.com/charmbracelet/bubbletea"
)
// Type specifies the way we render pagination.
type Type int
// Pagination rendering options.
const (
Arabic Type = iota
Dots
)
// Model is the Bubble Tea model for this user interface.
type Model struct {
Type Type
Page int
PerPage int
TotalPages int
ActiveDot string
InactiveDot string
ArabicFormat string
UsePgUpPgDownKeys bool
UseLeftRightKeys bool
UseUpDownKeys bool
UseHLKeys bool
UseJKKeys bool
}
// SetTotalPages is a helper function for calculating the total number of pages
// from a given number of items. It's use is optional since this pager can be
// used for other things beyond navigating sets. Note that it both returns the
// number of total pages and alters the model.
func (m *Model) SetTotalPages(items int) int {
if items < 1 {
return m.TotalPages
}
n := items / m.PerPage
if items%m.PerPage > 0 {
n++
}
m.TotalPages = n
return n
}
// ItemsOnPage is a helper function for returning the numer of items on the
// current page given the total numer of items passed as an argument.
func (m Model) ItemsOnPage(totalItems int) int {
if totalItems < 1 {
return 0
}
start, end := m.GetSliceBounds(totalItems)
return end - start
}
// GetSliceBounds is a helper function for paginating slices. Pass the length
// of the slice you're rendering and you'll receive the start and end bounds
// corresponding the to pagination. For example:
//
// bunchOfStuff := []stuff{...}
// start, end := model.GetSliceBounds(len(bunchOfStuff))
// sliceToRender := bunchOfStuff[start:end]
//
func (m *Model) GetSliceBounds(length int) (start int, end int) {
start = m.Page * m.PerPage
end = min(m.Page*m.PerPage+m.PerPage, length)
return start, end
}
// PrevPage is a number function for navigating one page backward. It will not
// page beyond the first page (i.e. page 0).
func (m *Model) PrevPage() {
if m.Page > 0 {
m.Page--
}
}
// NextPage is a helper function for navigating one page forward. It will not
// page beyond the last page (i.e. totalPages - 1).
func (m *Model) NextPage() {
if !m.OnLastPage() {
m.Page++
}
}
// OnLastPage returns whether or not we're on the last page.
func (m Model) OnLastPage() bool {
return m.Page == m.TotalPages-1
}
// New creates a new model with defaults.
func New() Model {
return Model{
Type: Arabic,
Page: 0,
PerPage: 1,
TotalPages: 1,
ActiveDot: "•",
InactiveDot: "○",
ArabicFormat: "%d/%d",
UsePgUpPgDownKeys: true,
UseLeftRightKeys: true,
UseUpDownKeys: false,
UseHLKeys: true,
UseJKKeys: false,
}
}
// NewModel creates a new model with defaults.
//
// Deprecated. Use New instead.
var NewModel = New
// Update is the Tea update function which binds keystrokes to pagination.
func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
switch msg := msg.(type) {
case tea.KeyMsg:
if m.UsePgUpPgDownKeys {
switch msg.String() {
case "pgup":
m.PrevPage()
case "pgdown":
m.NextPage()
}
}
if m.UseLeftRightKeys {
switch msg.String() {
case "left":
m.PrevPage()
case "right":
m.NextPage()
}
}
if m.UseUpDownKeys {
switch msg.String() {
case "up":
m.PrevPage()
case "down":
m.NextPage()
}
}
if m.UseHLKeys {
switch msg.String() {
case "h":
m.PrevPage()
case "l":
m.NextPage()
}
}
if m.UseJKKeys {
switch msg.String() {
case "j":
m.PrevPage()
case "k":
m.NextPage()
}
}
}
return m, nil
}
// View renders the pagination to a string.
func (m Model) View() string {
switch m.Type {
case Dots:
return m.dotsView()
default:
return m.arabicView()
}
}
func (m Model) dotsView() string {
var s string
for i := 0; i < m.TotalPages; i++ {
if i == m.Page {
s += m.ActiveDot
continue
}
s += m.InactiveDot
}
return s
}
func (m Model) arabicView() string {
return fmt.Sprintf(m.ArabicFormat, m.Page+1, m.TotalPages)
}
func min(a, b int) int {
if a < b {
return a
}
return b
}