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+.idea
+build/

@@ -0,0 +1,3 @@ 
+module git.sophuwu.com/rbprompt
+
+go 1.24.1

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+package rbprompt
+
+/*
+FMT strings:
+
+%u = username
+%h = hostname
+%i = ip address as colours
+%e = random emote
+%l = line number
+
+%<n>p = last <n> directories in the current working directory
+%p = current working directory, short for %0p
+
+*/
+
+import (
+	"fmt"
+	"math"
+	"math/rand"
+	"strings"
+)
+
+var (
+	// EmoteEyes contains characters that can be used as eyes in emotes.
+	// If this is empty, using %e in the prompt will cause an error.
+	EmoteEyes = ":;="
+	// EmoteMouths contains characters that can be used as mouths in emotes.
+	// If this is empty, using %e in the prompt will cause an error.
+	EmoteMouths = ")3>]DPO"
+)
+
+func randInt(max int) int {
+	return rand.Int() % max
+}
+
+func emote() string {
+	lenEyes := len(EmoteEyes)
+	lenMouths := len(EmoteMouths)
+	if lenEyes == 0 || lenMouths == 0 {
+		return ""
+	}
+	return string(EmoteEyes[randInt(lenEyes)]) + string(EmoteMouths[randInt(lenMouths)])
+}
+
+type Rainbow struct {
+	R, G, B, S int
+}
+
+func (r *Rainbow) init() {
+	r.R = 255
+	r.G = 0
+	r.B = 0
+	r.S = 55 - randInt(20)
+}
+
+func (r *Rainbow) copy() Rainbow {
+	return Rainbow{r.R, r.G, r.B, r.S}
+}
+
+func (r *Rainbow) next() {
+	if r.S <= 0 || (r.R == r.G && r.G == r.B) {
+		r.init()
+		return
+	}
+	for v := []*int{&r.R, &r.G, &r.B}; ; v[0], v[1], v[2] = v[1], v[2], v[0] {
+		if *v[0] == 255 && *v[2] == 000 {
+			*v[1] += r.S
+			if *v[1] > 255 {
+				*v[0] += 255 - *v[1]
+				*v[1] = 255
+			}
+			break
+		} else if *v[1] == 255 && *v[2] == 000 {
+			*v[0] -= r.S
+			if *v[0] < 0 {
+				*v[2] += 0 - *v[0]
+				*v[0] = 0
+			}
+			break
+		}
+	}
+}
+
+func (r *Rainbow) escape() string {
+	return fmt.Sprintf(ESCAPESTR+"38;2;%d;%d;%dm", r.R, r.G, r.B)
+}
+
+func (r *Rainbow) colour(in string) (out string) {
+	for i := range in {
+		out += r.escape() + in[i:i+1]
+		r.next()
+	}
+	out += "\033[0m"
+	return
+}
+
+type PS struct {
+	LineNo  uint
+	NoColor bool
+	Current string
+	Fmt,
+	User,
+	Home,
+	HostName,
+	PWD string
+	HostIP  [4]byte
+	Rainbow Rainbow
+}
+
+func (p *PS) String() string {
+	return p.Current
+}
+
+var ESCAPESTR = "\033["
+
+func (p *PS) ip2col() string {
+	if p.NoColor {
+		return ""
+	}
+	n := func() func() int {
+		i := 0
+		return func() int {
+			i++
+			return int(p.HostIP[i-1])*216/256 + 16
+		}
+	}()
+	return fmt.Sprintf(ESCAPESTR+"48;5;%d;38;5;%dm▄"+ESCAPESTR+"48;5;%d;38;5;%dm▄"+ESCAPESTR+"0m", n(), n(), n(), n())
+}
+
+func (p *PS) pwd(n int) string {
+	pwd := p.PWD
+	trimmed := false
+	if strings.HasPrefix(pwd, p.Home) {
+		trimmed = true
+		pwd = strings.TrimPrefix(pwd, p.Home)
+		if len(pwd) == 0 {
+			pwd = "~"
+		} else {
+			if pwd[0] != '/' {
+				pwd = "/" + pwd
+			}
+			pwd = "~" + pwd
+		}
+	}
+	if n <= 0 {
+		return pwd
+	}
+	a := strings.Split(pwd, "/")
+	if !trimmed {
+		a = append([]string{"/"}, a...)
+	}
+	ll := len(a) - 1
+	s := ""
+	for j := 0; j < n && j <= ll; j++ {
+		s = a[ll-j] + " " + s
+	}
+	return strings.TrimSpace(s)
+}
+
+func errGen(fnName string) func(s string) error {
+	return func(s string) error {
+		return fmt.Errorf("rbprompt: %s: %s", fnName, s)
+	}
+}
+
+func (p *PS) doFmt(rbfn *func(string) string, dst *string, f *string, i *int) error {
+	errFn := errGen("PS.doFmt")
+	s := ""
+	var j int = *i
+	*i++
+	if *i >= len(*f) {
+		return errFn("unexpected end of format string")
+	}
+	switch (*f)[*i] {
+	case 'u':
+		s = p.User
+		break
+	case 'h':
+		s = p.HostName
+		break
+	case 'i':
+		*dst += p.ip2col()
+		*i++
+		return nil
+	case 'e':
+		if ss := emote(); len(ss) == 2 {
+			s = ss
+		} else {
+			return errFn("cannot use %e in format string if emote list is empty")
+		}
+		break
+	case 'p':
+		s = p.pwd(0)
+		break
+	case 'l':
+		s = fmt.Sprint(p.LineNo)
+		break
+	case '%':
+		s = "%"
+		break
+	default:
+		for l := 0; *i < len(*f); *i++ {
+			if (*f)[*i] >= '0' && (*f)[*i] <= '9' {
+				l = l*10 + int((*f)[*i]-'0')
+				continue
+			} else if (*f)[*i] == 'p' {
+				s = p.pwd(l)
+			}
+			break
+		}
+		break
+	}
+	if s == "" {
+		return errFn("invalid format " + (*f)[j:*i])
+	}
+	*dst += (*rbfn)(s)
+	*i++
+	return nil
+}
+
+func (p *PS) Next() error {
+	p.Rainbow.next()
+	r := p.Rainbow.copy()
+	r.S += int(10 * (math.Sin(float64(p.LineNo) * math.Pi / 10)))
+
+	p.Current = ""
+	f := p.Fmt
+	var i int
+	var err error
+	rbfn := r.colour
+	if p.NoColor {
+		rbfn = func(in string) string {
+			return in
+		}
+	}
+	for {
+		i = strings.Index(f, "%")
+		if i < 0 {
+			p.Current += rbfn(f)
+			break
+		}
+		if i > 0 {
+			p.Current += rbfn(f[:i])
+		}
+		if err = p.doFmt(&rbfn, &p.Current, &f, &i); err != nil {
+			return err
+		}
+		f = f[i:]
+	}
+	p.LineNo++
+	return nil
+}