Add ScriptSrcs to add extra scripts URLs to load

Summary: This allows importing plugins from local and external hosts.

```
	r.Get("/swagger/*", httpSwagger.Handler(
		httpSwagger.ScriptSrc("/static/swagger-helper.js"),
		httpSwagger.ScriptSrc("https://unpkg.com/[email protected]/build/index.js"),
		httpSwagger.Plugins([]string{"DisableTryItOutWithoutServersPlugin"},
		httpSwagger.URL("http://localhost:1323/swagger/doc.json"), //The url pointing to API definition
	))
```

Closes swaggo#83

Test Plan: Updated existing tests. Added example in example/go-chi/

example/go-chi/docs/docs.go

@@ -1,17 +1,10 @@
-// Package docs GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
+// Package docs GENERATED BY SWAG; DO NOT EDIT
 // This file was generated by swaggo/swag
 package docs
 
-import (
-	"bytes"
-	"encoding/json"
-	"strings"
-	"text/template"
+import "github.com/swaggo/swag"
 
-	"github.com/swaggo/swag"
-)
-
-var doc = `{
+const docTemplate = `{
     "schemes": {{ marshal .Schemes }},
     "swagger": "2.0",
     "info": {
@@ -34,56 +27,18 @@ var doc = `{
     "paths": {}
 }`
 
-type swaggerInfo struct {
-	Version     string
-	Host        string
-	BasePath    string
-	Schemes     []string
-	Title       string
-	Description string
-}
-
 // SwaggerInfo holds exported Swagger Info so clients can modify it
-var SwaggerInfo = swaggerInfo{
-	Version:     "1.0",
-	Host:        "petstore.swagger.io",
-	BasePath:    "/v2",
-	Schemes:     []string{},
-	Title:       "Swagger Example API",
-	Description: "This is a sample server Petstore server.",
-}
-
-type s struct{}
-
-func (s *s) ReadDoc() string {
-	sInfo := SwaggerInfo
-	sInfo.Description = strings.Replace(sInfo.Description, "\n", "\\n", -1)
-
-	t, err := template.New("swagger_info").Funcs(template.FuncMap{
-		"marshal": func(v interface{}) string {
-			a, _ := json.Marshal(v)
-			return string(a)
-		},
-		"escape": func(v interface{}) string {
-			// escape tabs
-			str := strings.Replace(v.(string), "\t", "\\t", -1)
-			// replace " with \", and if that results in \\", replace that with \\\"
-			str = strings.Replace(str, "\"", "\\\"", -1)
-			return strings.Replace(str, "\\\\\"", "\\\\\\\"", -1)
-		},
-	}).Parse(doc)
-	if err != nil {
-		return doc
-	}
-
-	var tpl bytes.Buffer
-	if err := t.Execute(&tpl, sInfo); err != nil {
-		return doc
-	}
-
-	return tpl.String()
+var SwaggerInfo = &swag.Spec{
+	Version:          "1.0",
+	Host:             "petstore.swagger.io",
+	BasePath:         "/v2",
+	Schemes:          []string{},
+	Title:            "Swagger Example API",
+	Description:      "This is a sample server Petstore server.",
+	InfoInstanceName: "swagger",
+	SwaggerTemplate:  docTemplate,
 }
 
 func init() {
-	swag.Register(swag.Name, &s{})
+	swag.Register(SwaggerInfo.InstanceName(), SwaggerInfo)
 }

example/go-chi/main.go

@@ -29,6 +29,10 @@ func main() {
 	r.Get("/swagger/*", httpSwagger.Handler(
 		httpSwagger.BeforeScript("console.log('before 1')"),
 		httpSwagger.BeforeScript("console.log('before 2')"),
+		httpSwagger.ScriptSrc("https://unpkg.com/[email protected]/dist/htm.js"),
+		httpSwagger.ScriptSrc("https://unpkg.com/[email protected]/umd/react.production.min.js"),
+		httpSwagger.ScriptSrc("/static/myplugin.js"),
+		httpSwagger.Plugins([]string{"MyPlugin"}),
 		httpSwagger.URL("http://localhost:1323/swagger/doc.json"), //The url pointing to API definition
 	))
 

example/go-chi/static/myplugin.js

@@ -0,0 +1,80 @@
+// Swagger UI Version: 4.15.5
+
+'use strict';
+
+function _typeof(obj) {
+  if (typeof Symbol === 'function' && typeof Symbol.iterator === 'symbol') {
+    _typeof = function _typeof(obj) {
+      return typeof obj;
+    };
+  } else {
+    _typeof = function _typeof(obj) {
+      return obj &&
+        typeof Symbol === 'function' &&
+        obj.constructor === Symbol &&
+        obj !== Symbol.prototype
+        ? 'symbol'
+        : typeof obj;
+    };
+  }
+  return _typeof(obj);
+}
+
+// From: https://raw.githubusercontent.com/chilts/umd-template/master/template.js
+(function (f) {
+  // module name and requires
+  var name = 'MyPlugin';
+  var requires = []; // CommonJS
+
+  if (
+    (typeof exports === 'undefined' ? 'undefined' : _typeof(exports)) === 'object' &&
+    typeof module !== 'undefined'
+  ) {
+    module.exports = f.apply(
+      null,
+      requires.map(function (r) {
+        return require(r);
+      })
+    ); // RequireJS
+  } else if (typeof define === 'function' && define.amd) {
+    define(requires, f); // <script>
+  } else {
+    var g;
+
+    if (typeof window !== 'undefined') {
+      g = window;
+    } else if (typeof global !== 'undefined') {
+      g = global;
+    } else if (typeof self !== 'undefined') {
+      g = self;
+    } else {
+      // works providing we're not in "use strict";
+      // needed for Java 8 Nashorn
+      // seee https://github.com/facebook/react/issues/3037
+      g = this;
+    }
+
+    g[name] = f.apply(
+      null,
+      requires.map(function (r) {
+        return g[r];
+      })
+    );
+  }
+})(function () {
+  return function (system) {
+    return {
+        wrapComponents: {
+            info: (Original, system) => (props) => {
+                const html = htm.bind(React.createElement);
+                // Uses https://github.com/developit/htm to render JSX.
+                return html`
+                <div>
+                    <h3>Hello world! I am above the Info component.</h3>
+                    <Original {...props} />
+                </div>`;
+            }
+        },
+    };
+  };
+});

swagger.go

@@ -24,6 +24,7 @@ type Config struct {
 	BeforeScripts        []template.JS
 	AfterScripts         []template.JS
 	Plugins              []template.JS
+	ScriptSrcs           []string // URLs to the extra scripts to load
 	UIConfig             map[template.JS]template.JS
 	DeepLinking          bool
 	PersistAuthorization bool
@@ -84,6 +85,13 @@ func Plugins(plugins []string) func(*Config) {
 	}
 }
 
+// Adds `<script src="src"></script>`
+func ScriptSrc(src string) func(*Config) {
+	return func(c *Config) {
+		c.ScriptSrcs = append(c.ScriptSrcs, src)
+	}
+}
+
 // UIConfig specifies additional SwaggerUIBundle config object properties.
 func UIConfig(props map[string]string) func(*Config) {
 	return func(c *Config) {
@@ -259,6 +267,9 @@ const indexTempl = `<!-- HTML for static distribution bundle build -->
 
 <script src="./swagger-ui-bundle.js"> </script>
 <script src="./swagger-ui-standalone-preset.js"> </script>
+{{- range $script := .ScriptSrcs }}
+<script src="{{$script}}"> </script>
+{{- end}}
 <script>
 window.onload = function() {
   {{- range $script := .BeforeScripts }}

swagger_test.go

@@ -231,6 +231,13 @@ func TestConfigURL(t *testing.T) {
     // Some plugin
   });`),
 		},
+		{
+			desc: "configure ScriptSrcs",
+			exp: &Config{
+				ScriptSrcs: []string{`/scripts/helper.js`},
+			},
+			cfgfn: ScriptSrc(`/scripts/helper.js`),
+		},
 	}
 
 	for _, fix := range fixtures {
@@ -335,6 +342,8 @@ func TestUIConfigOptions(t *testing.T) {
 
 <script src="./swagger-ui-bundle.js"> </script>
 <script src="./swagger-ui-standalone-preset.js"> </script>
+<script src="./a.js"> </script>
+<script src="./b.js"> </script>
 <script>
 `
 	ftr := `
@@ -353,6 +362,7 @@ func TestUIConfigOptions(t *testing.T) {
 				DocExpansion:         "list",
 				DomID:                "swagger-ui",
 				PersistAuthorization: false,
+				ScriptSrcs:           []string{"./a.js", "./b.js"},
 			},
 			exp: `window.onload = function() {
   
@@ -396,6 +406,7 @@ func TestUIConfigOptions(t *testing.T) {
 					"SomePlugin",
 					"AnotherPlugin",
 				},
+				ScriptSrcs: []string{"./a.js", "./b.js"},
 				UIConfig: map[template.JS]template.JS{
 					"showExtensions":        "true",
 					"onComplete":            `() => { window.ui.setBasePath('v3'); }`,