1package editor
 2
 3type historyState struct {
 4	previouslyScrollingPromptHistory bool
 5	promptHistoryIndex               int
 6	existingValue                    string
 7	historyCache                     []string
 8}
 9
10type History interface {
11	ExistingValue() string
12	Value() string
13	ScrollUp()
14	ScrollDown()
15}
16
17func InitialiseHistory(existingValue string, messages []string) History {
18	return &historyState{
19		existingValue:      existingValue,
20		historyCache:       messages,
21		promptHistoryIndex: len(messages) - 1,
22	}
23}
24
25func (h *historyState) Value() string {
26	if len(h.historyCache) == 0 {
27		return h.existingValue
28	}
29	return h.historyCache[h.promptHistoryIndex]
30}
31
32func (h *historyState) ExistingValue() string {
33	return h.existingValue
34}
35
36func (h *historyState) ScrollUp() {
37	h.promptHistoryIndex--
38	h.clampIndex()
39}
40
41func (h *historyState) ScrollDown() {
42	h.promptHistoryIndex++
43	h.clampIndex()
44}
45
46func (h *historyState) clampIndex() {
47	if h.promptHistoryIndex > len(h.historyCache)-1 {
48		h.promptHistoryIndex = len(h.historyCache) - 1
49		return
50	}
51
52	if h.promptHistoryIndex < 0 {
53		h.promptHistoryIndex = 0
54	}
55}