Clarify path param naming (#32969)

In history (from some legacy frameworks), both `:name` and `name` are
supported as path path name, `:name` is an alias to `name`.

To make code consistent, now we should only use `name` but not `:name`.

Also added panic check in related functions to make sure the name won't
be abused in case some downstreams still use them.

services/context/base_path.go

@@ -0,0 +1,47 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package context
+
+import (
+	"net/url"
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// PathParam returns the param in request path, eg: "/{var}" => "/a%2fb", then `var == "a/b"`
+func (b *Base) PathParam(name string) string {
+	s, err := url.PathUnescape(b.PathParamRaw(name))
+	if err != nil && !setting.IsProd {
+		panic("Failed to unescape path param: " + err.Error() + ", there seems to be a double-unescaping bug")
+	}
+	return s
+}
+
+// PathParamRaw returns the raw param in request path, eg: "/{var}" => "/a%2fb", then `var == "a%2fb"`
+func (b *Base) PathParamRaw(name string) string {
+	if strings.HasPrefix(name, ":") {
+		setting.PanicInDevOrTesting("path param should not start with ':'")
+		name = name[1:]
+	}
+	return chi.URLParam(b.Req, name)
+}
+
+// PathParamInt64 returns the param in request path as int64
+func (b *Base) PathParamInt64(p string) int64 {
+	v, _ := strconv.ParseInt(b.PathParam(p), 10, 64)
+	return v
+}
+
+// SetPathParam set request path params into routes
+func (b *Base) SetPathParam(name, value string) {
+	if strings.HasPrefix(name, ":") {
+		setting.PanicInDevOrTesting("path param should not start with ':'")
+		name = name[1:]
+	}
+	chi.RouteContext(b).URLParams.Add(name, url.PathEscape(value))
+}