From 40a6ff1e45544fb2302206e1c59882e4348a52fc Mon Sep 17 00:00:00 2001
From: "Gustavo \"Guz\" L de Mello" <contact@guz.one>
Date: Fri, 8 Aug 2025 19:17:57 -0300
Subject: [PATCH] feat(smalltrip,multiplexer): pattern options and rules
 multiplexer

---
 smalltrip/multiplexer/patterns.go | 153 ++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 smalltrip/multiplexer/patterns.go

diff --git a/smalltrip/multiplexer/patterns.go b/smalltrip/multiplexer/patterns.go
new file mode 100644
index 0000000..08162a2
--- /dev/null
+++ b/smalltrip/multiplexer/patterns.go
@@ -0,0 +1,153 @@
+package multiplexer
+
+import (
+	"fmt"
+	"net/http"
+	"slices"
+	"strings"
+)
+
+func WithPatternsOptions(mux Multiplexer, opts ...PatternOption) Multiplexer {
+	return &patternsMux{opts: opts, Multiplexer: mux}
+}
+
+func AddTrailingSlash() PatternOption {
+	return func(s string) string {
+		if strings.HasSuffix(s, "...}") {
+			return s
+		}
+		// If the pattern is /image.html{$}, we modify it to be /image.html/{$}
+		if strings.HasSuffix(s, "{$}") && !strings.HasSuffix(s, "/{$}") {
+			return strings.TrimSuffix(s, "{$}") + "/{$}"
+		}
+		if !strings.HasSuffix(s, "/") {
+			return s + "/"
+		}
+		return s
+	}
+}
+
+func RemoveTrailingSlash() PatternOption {
+	return func(s string) string {
+		s = strings.TrimSuffix(s, "/")
+		if strings.HasSuffix(s, "/{$}") {
+			return strings.TrimSuffix(s, "/{$}") + "{$}"
+		}
+		return s
+	}
+}
+
+func AddStrictEnd() PatternOption {
+	return func(s string) string {
+		if strings.HasSuffix(s, "{$}") {
+			return s
+		}
+		return s + "{$}"
+	}
+}
+
+func RemoteStrictEnd() PatternOption {
+	return func(s string) string {
+		return strings.TrimSuffix(s, "{$}")
+	}
+}
+
+type PatternOption func(string) string
+
+func WithPatternRules(mux Multiplexer, rules ...PatternRule) Multiplexer {
+	opts := make([]PatternOption, len(rules))
+	for i, r := range rules {
+		opts[i] = func(s string) string { r(s); return s }
+	}
+	return &patternsMux{Multiplexer: mux, opts: opts}
+}
+
+func NoTrailingSlash() PatternRule {
+	return func(s string) {
+		if strings.HasSuffix(s, "/") || strings.HasSuffix(s, "/{$}") {
+			panic(fmt.Sprintf("no-trailing-slash: pattern %q has trailing slash", s))
+		}
+	}
+}
+
+func EnsureTrailingSlash() PatternRule {
+	return func(s string) {
+		if !strings.HasSuffix(s, "/{$}") && !strings.HasSuffix(s, "/") && !strings.HasSuffix(s, "...}") {
+			panic(fmt.Sprintf("trailing-slash: pattern %q doesn't has a trailing slash", s))
+		}
+	}
+}
+
+func NoMethod() PatternRule {
+	return func(s string) {
+		if len(strings.Split(s, " ")) > 1 {
+			panic(fmt.Sprintf("no-method: pattern %q has a method", s))
+		}
+	}
+}
+
+func EnsureMethod(methods ...string) PatternRule {
+	if len(methods) == 0 && methods != nil {
+		methods = DefaultMethods
+	}
+	return func(s string) {
+		sp := strings.Split(s, " ")
+		if len(sp) <= 0 {
+			panic(fmt.Sprintf("method: pattern %q doesn't has a method", s))
+		}
+		if methods != nil {
+			if slices.Contains(methods, sp[0]) {
+				panic(fmt.Sprintf("method: pattern %q doesn't has a valid method, valid methods are: %s", s, strings.Join(methods, ", ")))
+			}
+		}
+	}
+}
+
+var DefaultMethods = []string{
+	http.MethodConnect,
+	http.MethodDelete,
+	http.MethodGet,
+	http.MethodHead,
+	http.MethodOptions,
+	http.MethodPatch,
+	http.MethodPost,
+	http.MethodPut,
+	http.MethodTrace,
+}
+
+func EnsureStrictEnd() PatternRule {
+	return func(s string) {
+		if !strings.HasSuffix(s, "{$}") && !strings.HasSuffix(s, "...}") {
+			panic(fmt.Sprintf(`strict-end: pattern %q doesn't end with "{$}"`, s))
+		}
+	}
+}
+
+func NoStrictEnd() PatternRule {
+	return func(s string) {
+		if strings.HasSuffix(s, "{$}") {
+			panic(fmt.Sprintf(`no-strict-end: pattern %q ends with "{$}"`, s))
+		}
+	}
+}
+
+type PatternRule func(string)
+
+type patternsMux struct {
+	opts []PatternOption
+	Multiplexer
+}
+
+func (pm *patternsMux) HandleFunc(p string, h func(http.ResponseWriter, *http.Request)) {
+	for _, po := range pm.opts {
+		p = po(p)
+	}
+	pm.Multiplexer.HandleFunc(p, h)
+}
+
+func (pm *patternsMux) Handle(p string, h http.Handler) {
+	for _, po := range pm.opts {
+		p = po(p)
+	}
+	pm.Multiplexer.Handle(p, h)
+}