package render import ( "fmt" ) // BrowseConfig defines the availability and display parameters for page browsing. type BrowseConfig struct { NextAvailable bool NextSelector string NextTitle string PreviousAvailable bool PreviousSelector string PreviousTitle string } // Default browse settings for convenience. func DefaultBrowseConfig() BrowseConfig { return BrowseConfig{ NextAvailable: true, NextSelector: "11", NextTitle: "next", PreviousAvailable: true, PreviousSelector: "22", PreviousTitle: "previous", } } type Menu struct { menu [][2]string browse BrowseConfig pageCount uint16 canNext bool canPrevious bool outputSize uint16 } // NewMenu creates a new Menu with an explicit page count. func NewMenu() *Menu { return &Menu{} } // WithBrowseConfig defines the criteria for page browsing. func(m *Menu) WithPageCount(pageCount uint16) *Menu { m.pageCount = pageCount return m } // WithSize defines the maximum byte size of the rendered menu. func(m *Menu) WithOutputSize(outputSize uint16) *Menu { m.outputSize = outputSize return m } // GetOutputSize returns the defined heuristic menu size. func(m *Menu) GetOutputSize() uint32 { return uint32(m.outputSize) } // WithBrowseConfig defines the criteria for page browsing. func(m *Menu) WithBrowseConfig(cfg BrowseConfig) *Menu { m.browse = cfg return m } // GetBrowseConfig returns a copy of the current state of the browse configuration. func(m *Menu) GetBrowseConfig() BrowseConfig { return m.browse } // Put adds a menu option to the menu rendering. func(m *Menu) Put(selector string, title string) error { m.menu = append(m.menu, [2]string{selector, title}) return nil } // Render returns the full current state of the menu as a string. // // After this has been executed, the state of the menu will be empty. func(m *Menu) Render(idx uint16) (string, error) { var menuCopy [][2]string for _, v := range m.menu { menuCopy = append(menuCopy, v) } err := m.applyPage(idx) if err != nil { return "", err } r := "" for true { l := len(r) choice, title, err := m.shiftMenu() if err != nil { break } if l > 0 { r += "\n" } r += fmt.Sprintf("%s:%s", choice, title) } m.menu = menuCopy return r, nil } // add available browse options. func(m *Menu) applyPage(idx uint16) error { if m.pageCount == 0 { if idx > 0 { return fmt.Errorf("index %v > 0 for non-paged menu", idx) } return nil } else if idx >= m.pageCount { return fmt.Errorf("index %v out of bounds (%v)", idx, m.pageCount) } m.reset() if idx == m.pageCount - 1 { m.canNext = false } if idx == 0 { m.canPrevious = false } if m.canNext { err := m.Put(m.browse.NextSelector, m.browse.NextTitle) if err != nil { return err } } if m.canPrevious { err := m.Put(m.browse.PreviousSelector, m.browse.PreviousTitle) if err != nil { return err } } return nil } // removes and returns the first of remaining menu options. // fails if menu is empty. func(m *Menu) shiftMenu() (string, string, error) { if len(m.menu) == 0 { return "", "", fmt.Errorf("menu is empty") } r := m.menu[0] m.menu = m.menu[1:] return r[0], r[1], nil } func(m *Menu) reset() { if m.browse.NextAvailable { m.canNext = true } if m.browse.PreviousAvailable { m.canPrevious = true } } func(m *Menu) ReservedSize() uint16 { return m.outputSize }