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// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Paul Buetow
package repl
import (
"fmt"
"slices"
"strings"
)
// GetHelp returns the formatted help text for a topic.
// If topic is empty, it returns the general help overview.
func GetHelp(topic string) string {
if topic == "" {
return getGeneralHelp()
}
// Look up by operator name or alias
topic = strings.ToLower(topic)
t, ok := helpByTopic[topic]
if !ok {
t, ok = helpByAlias[topic]
}
if !ok {
return fmt.Sprintf("No help for %q.\n\nType 'help' for an overview, or 'help categories' to list all topics.", topic)
}
if t.Render != nil {
return t.Render()
}
return formatTopic(t)
}
// GetAllTopics returns a sorted list of all help topic names.
func GetAllTopics() []string {
topics := make([]string, 0, len(helpByTopic))
for op := range helpByTopic {
topics = append(topics, op)
}
slices.Sort(topics)
return topics
}
// GetCompletionTopics returns all help topics suitable for tab completion.
// Includes operator names and aliases from all registered HelpTopic entries.
func GetCompletionTopics() []string {
seen := make(map[string]struct{})
var topics []string
// Add all operator names (skip "help" itself — no need to complete help help)
for op, t := range helpByTopic {
if op == "help" {
continue
}
topics = append(topics, op)
seen[op] = struct{}{}
// Add aliases
for _, a := range t.Aliases {
if _, ok := seen[a]; !ok {
topics = append(topics, a)
seen[a] = struct{}{}
}
}
}
slices.Sort(topics)
return topics
}
// getGeneralHelp returns the overview help text.
func getGeneralHelp() string {
var sb strings.Builder
sb.WriteString("gt - Reverse Polish Notation (RPN) Calculator\n\n")
sb.WriteString("Help Topics:\n")
sb.WriteString(" help [topic] Show help for a specific topic\n")
sb.WriteString(" help categories List all available help topics by category\n\n")
sb.WriteString("REPL Commands:\n")
for _, op := range helpByCat["REPL"] {
t := helpByTopic[op]
sb.WriteString(fmt.Sprintf(" %-12s %s\n", op, t.Description))
}
sb.WriteString("\nArithmetic Operators:\n")
for _, op := range helpByCat["Arithmetic"] {
t := helpByTopic[op]
sb.WriteString(fmt.Sprintf(" %-8s %s\n", op, t.Description))
}
sb.WriteString("\nComparison Operators:\n")
for _, op := range helpByCat["Comparison"] {
t := helpByTopic[op]
sb.WriteString(fmt.Sprintf(" %-8s %s\n", op, t.Description))
}
sb.WriteString("\nStack Operators:\n")
for _, op := range helpByCat["Stack"] {
t := helpByTopic[op]
sb.WriteString(fmt.Sprintf(" %-12s %s\n", op, t.Description))
}
sb.WriteString("\nHyper (n-ary) Operators:\n")
for _, op := range helpByCat["Hyper"] {
t := helpByTopic[op]
sb.WriteString(fmt.Sprintf(" %-8s %s\n", op, t.Description))
}
sb.WriteString("\nVariables and Constants:\n")
for _, cat := range []string{"Variables", "Constants"} {
for _, op := range helpByCat[cat] {
t := helpByTopic[op]
sb.WriteString(fmt.Sprintf(" %-16s %s\n", op, t.Description))
}
}
sb.WriteString("\nKeyboard Shortcuts:\n")
sb.WriteString(" Ctrl+A Go to beginning of line\n")
sb.WriteString(" Ctrl+E Go to end of line\n")
sb.WriteString(" Ctrl+L Clear screen\n")
sb.WriteString(" Ctrl+D Exit / delete character\n")
sb.WriteString(" Up/Down History navigation\n")
sb.WriteString(" Tab Auto-complete\n")
sb.WriteString("\nUse 'help <topic>' for details on any operator or command.\n")
sb.WriteString("Use 'help categories' to see all available topics.\n")
return sb.String()
}
// formatTopic returns the detailed help for a single HelpTopic.
func formatTopic(t *HelpTopic) string {
var sb strings.Builder
sb.WriteString(fmt.Sprintf("Topic: %s (Category: %s)\n", t.Operator, t.Category))
if len(t.Aliases) > 0 {
sb.WriteString(fmt.Sprintf("Aliases: %s\n", strings.Join(t.Aliases, ", ")))
}
sb.WriteString(fmt.Sprintf("Usage: %s\n", t.Usage))
sb.WriteString(fmt.Sprintf("Desc: %s\n", t.Description))
sb.WriteString("\nExamples:\n")
for _, ex := range t.Examples {
sb.WriteString(fmt.Sprintf(" %s\n", ex))
}
return sb.String()
}
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