Migrate to multiplexer concept

This introduces a layered approach to handling HTTP requests:

- server layer
- path layer
- request layer

The multiplexer file cares about the path layer. It delegates the
request handling to handlers from the request layer.

3 files changed, 301 insertions, 221 deletions

diff --git a/handler.go b/handler.go
index fc3d653..2cb8787 100644
--- a/handler.go
+++ b/handler.go
@@ -17,15 +17,6 @@ const (
 	VALID_ID_REGEX = `^[0-9]+$`
 )
 
-func static(filename string, staticRoot string) func(http.ResponseWriter, *http.Request) {
-
-	return func(w http.ResponseWriter, r *http.Request) {
-		path := filepath.Join(staticRoot, filename)
-		log.Printf("Trying to serve: %s\n", path)
-		http.ServeFile(w, r, path)
-	}
-}
-
 func indexGet(w http.ResponseWriter, r *http.Request, db *Database, templateRoot string) {
 
 	// get data from database
@@ -62,167 +53,184 @@ func indexGet(w http.ResponseWriter, r *http.Request, db *Database, templateRoot
 	ServeTemplate(w, "index", path, elements)
 }
 
-func recipe(db *Database, templateRoot string) func(http.ResponseWriter, *http.Request) {
+func recipeGet(w http.ResponseWriter, r *http.Request, db *Database, templateRoot string) {
 
-	return func(w http.ResponseWriter, r *http.Request) {
+	// get id from URL parameters
+	ids := r.URL.Query()["id"]
+	if len(ids) != 1 {
+		msg := fmt.Sprintf("Exactly 1 'id' URL parameter expected but %d provided.", len(ids))
+		http.Error(w, msg, 400)
+		return
+	}
+	idStr := ids[0]
 
-		// get id from URL parameters
-		ids := r.URL.Query()["id"]
-		if len(ids) != 1 {
-			msg := fmt.Sprintf("Exactly 1 'id' URL parameter expected but %d provided.", len(ids))
-			http.Error(w, msg, 400)
-			return
-		}
-		idStr := ids[0]
+	// validate id
+	idRegex := regexp.MustCompile(VALID_ID_REGEX)
+	if !(idRegex.MatchString(idStr)) {
+		http.Error(w, "Bad 'id' URL parameter.", 400)
+		return
+	}
+
+	// get data from database
+	cmd := fmt.Sprintf("SELECT title,upstream_url,description_markdown FROM recipes WHERE (id='%s');", idStr)
+	log.Printf("Query: %s", cmd)
+	rows, err := db.Backend.Query(cmd)
+	if err != nil {
+		http.Error(w, "Database returned error: " + err.Error(), 500)
+		return
+	}
+	defer rows.Close()
+
+	// prepare data store
+	type Element struct {
+		Id string
+		Title string
+		UpstreamUrl string
+		DescriptionMarkdown string
+		RenderedDescriptionMarkdown string
+	}
+	elements := make([]Element, 0)
 
-		// validate id
-		idRegex := regexp.MustCompile(VALID_ID_REGEX)
-		if !(idRegex.MatchString(idStr)) {
-			http.Error(w, "Bad 'id' URL parameter.", 400)
+	// scan database rows to data store
+	for rows.Next() {
+		var element Element
+		element.Id = idStr
+		err := rows.Scan(&element.Title, &element.UpstreamUrl, &element.DescriptionMarkdown)
+		if err != nil {
+			http.Error(w, "Could not parse recipe from database request.", 500)
 			return
+		} else {
+			elements = append(elements, element)
 		}
+	}
 
-		if r.Method == "GET" {
-
-			// get data from database
-			cmd := fmt.Sprintf("SELECT title,upstream_url,description_markdown FROM recipes WHERE (id='%s');", idStr)
-			log.Printf("Query: %s", cmd)
-			rows, err := db.Backend.Query(cmd)
-			if err != nil {
-				http.Error(w, "Database returned error: " + err.Error(), 500)
-				return
-			}
-			defer rows.Close()
-
-			// prepare data store
-			type Element struct {
-				Id string
-				Title string
-				UpstreamUrl string
-				DescriptionMarkdown string
-				RenderedDescriptionMarkdown string
-			}
-			elements := make([]Element, 0)
-
-			// scan database rows to data store
-			for rows.Next() {
-				var element Element
-				element.Id = idStr
-				err := rows.Scan(&element.Title, &element.UpstreamUrl, &element.DescriptionMarkdown)
-				if err != nil {
-					http.Error(w, "Could not parse recipe from database request.", 500)
-					return
-				} else {
-					elements = append(elements, element)
-				}
-			}
-
-			// check result
-			if len(elements) != 1 {
-				http.Error(w, "Expected exactly 1 recipe from database.", 500)
-				return
-			}
-
-			// render markdown
-			var buf bytes.Buffer
-			goldmark.Convert([]byte(elements[0].DescriptionMarkdown), &buf)
-			elements[0].RenderedDescriptionMarkdown = buf.String()
-
-			// render and return template
-			path := filepath.Join(templateRoot, "recipe.html")
-			ServeTemplate(w, "recipe", path, elements[0])
-		}
+	// check result
+	if len(elements) != 1 {
+		http.Error(w, "Expected exactly 1 recipe from database.", 500)
+		return
+	}
 
-		if r.Method == "POST" {
+	// render markdown
+	var buf bytes.Buffer
+	goldmark.Convert([]byte(elements[0].DescriptionMarkdown), &buf)
+	elements[0].RenderedDescriptionMarkdown = buf.String()
 
-			// read request body
-			buffer,_ := ioutil.ReadAll(r.Body)  // FIXME error handling
-			body := string(buffer)
-			updateRecipe(db, body, idStr)
+	// render and return template
+	path := filepath.Join(templateRoot, "recipe.html")
+	ServeTemplate(w, "recipe", path, elements[0])
+}
 
-		}
+func recipePost(w http.ResponseWriter, r *http.Request, db *Database) {
+
+	// get id from URL parameters
+	ids := r.URL.Query()["id"]
+	if len(ids) != 1 {
+		msg := fmt.Sprintf("Exactly 1 'id' URL parameter expected but %d provided.", len(ids))
+		http.Error(w, msg, 400)
+		return
 	}
+	idStr := ids[0]
+
+	// validate id
+	idRegex := regexp.MustCompile(VALID_ID_REGEX)
+	if !(idRegex.MatchString(idStr)) {
+		http.Error(w, "Bad 'id' URL parameter.", 400)
+		return
+	}
+
+	// read request body
+	buffer,_ := ioutil.ReadAll(r.Body)  // FIXME error handling
+	body := string(buffer)
+	updateRecipe(db, body, idStr)
 }
 
-func recipe_edit(db *Database, templateRoot string) func(http.ResponseWriter, *http.Request) {
+func recipeEditGet(w http.ResponseWriter, r *http.Request, db *Database, templateRoot string) {
 
-	return func(w http.ResponseWriter, r *http.Request) {
+	// get id from URL parameters
+	ids := r.URL.Query()["id"]
+	if len(ids) != 1 {
+		http.Error(w, "Exactly 1 'id' URL parameter expected.", 400)
+		return
+	}
+	idStr := ids[0]
 
-		// get id from URL parameters
-		ids := r.URL.Query()["id"]
-		if len(ids) != 1 {
-			http.Error(w, "Exactly 1 'id' URL parameter expected.", 400)
-			return
-		}
-		idStr := ids[0]
+	// validate id
+	idRegex := regexp.MustCompile(VALID_ID_REGEX)
+	if !(idRegex.MatchString(idStr)) {
+		http.Error(w, "Bad 'id' URL parameter.", 400)
+		return
+	}
+
+	// get data from database
+	cmd := fmt.Sprintf("SELECT title,upstream_url,description_markdown FROM recipes WHERE (id='%s');", idStr)
+	log.Printf("Query: %s", cmd)
+	rows, err := db.Backend.Query(cmd)
+	if err != nil {
+		http.Error(w, "Got error from database: " + err.Error(), 500)
+		return
+	}
+	defer rows.Close()
+
+	// prepare data store
+	type Element struct {
+		Id string
+		Title string
+		UpstreamUrl string
+		DescriptionMarkdown string
+		RenderedDescriptionMarkdown string
+	}
+	elements := make([]Element, 0)
 
-		// validate id
-		idRegex := regexp.MustCompile(VALID_ID_REGEX)
-		if !(idRegex.MatchString(idStr)) {
-			http.Error(w, "Bad 'id' URL parameter.", 400)
+	// scan database rows to data store
+	for rows.Next() {
+		var element Element
+		element.Id = idStr
+		err := rows.Scan(&element.Title, &element.UpstreamUrl, &element.DescriptionMarkdown)
+		if err != nil {
+			http.Error(w, "Could not parse recipe from database request.", 500)
 			return
+		} else {
+			elements = append(elements, element)
 		}
+	}
 
-		if r.Method == "GET" {
-
-			// get data from database
-			cmd := fmt.Sprintf("SELECT title,upstream_url,description_markdown FROM recipes WHERE (id='%s');", idStr)
-			log.Printf("Query: %s", cmd)
-			rows, err := db.Backend.Query(cmd)
-			if err != nil {
-				http.Error(w, "Got error from database: " + err.Error(), 500)
-				return
-			}
-			defer rows.Close()
-
-			// prepare data store
-			type Element struct {
-				Id string
-				Title string
-				UpstreamUrl string
-				DescriptionMarkdown string
-				RenderedDescriptionMarkdown string
-			}
-			elements := make([]Element, 0)
-
-			// scan database rows to data store
-			for rows.Next() {
-				var element Element
-				element.Id = idStr
-				err := rows.Scan(&element.Title, &element.UpstreamUrl, &element.DescriptionMarkdown)
-				if err != nil {
-					http.Error(w, "Could not parse recipe from database request.", 500)
-					return
-				} else {
-					elements = append(elements, element)
-				}
-			}
-
-			// check result
-			if len(elements) != 1 {
-				http.Error(w, "Did not get exactly one recipe from database.", 500)
-				return
-			}
-
-			// render markdown
-			// var buf bytes.Buffer
-			// goldmark.Convert([]byte(elements[0].DescriptionMarkdown), &buf)
-			// elements[0].RenderedDescriptionMarkdown = buf.String()
-
-			// render and return template
-			path := filepath.Join(templateRoot, "recipe_edit.html")
-			ServeTemplate(w, "recipe", path, elements[0])
-		}
+	// check result
+	if len(elements) != 1 {
+		http.Error(w, "Did not get exactly one recipe from database.", 500)
+		return
+	}
 
-		if r.Method == "POST" {
+	// render markdown
+	// var buf bytes.Buffer
+	// goldmark.Convert([]byte(elements[0].DescriptionMarkdown), &buf)
+	// elements[0].RenderedDescriptionMarkdown = buf.String()
 
-			// read request body
-			buffer,_ := ioutil.ReadAll(r.Body)  // FIXME error handling
-			body := string(buffer)
-			updateRecipe(db, body, idStr)
+	// render and return template
+	path := filepath.Join(templateRoot, "recipe_edit.html")
+	ServeTemplate(w, "recipe", path, elements[0])
+}
 
-		}
+func recipeEditPost(w http.ResponseWriter, r *http.Request, db *Database) {
+
+	// get id from URL parameters
+	ids := r.URL.Query()["id"]
+	if len(ids) != 1 {
+		http.Error(w, "Exactly 1 'id' URL parameter expected.", 400)
+		return
 	}
+	idStr := ids[0]
+
+	// validate id
+	idRegex := regexp.MustCompile(VALID_ID_REGEX)
+	if !(idRegex.MatchString(idStr)) {
+		http.Error(w, "Bad 'id' URL parameter.", 400)
+		return
+	}
+
+	// read request body
+	buffer,_ := ioutil.ReadAll(r.Body)  // FIXME error handling
+	body := string(buffer)
+	updateRecipe(db, body, idStr)
 }
 
 func updateRecipe(db *Database, body string, idStr string) {
@@ -242,64 +250,63 @@ func updateRecipe(db *Database, body string, idStr string) {
 	return
 }
 
-func image(storageRoot string) func(http.ResponseWriter, *http.Request) {
-
-	return func(w http.ResponseWriter, r *http.Request) {
-
-		// get ID
-		ids := r.URL.Query()["id"]
-		if len(ids) != 1 {
-			http.Error(w, "Expected exactly one 'id' URL parameter.", 400)
-			return
-		}
-		idStr := ids[0]
+func recipeImageGet(w http.ResponseWriter, r *http.Request, storage string) {
 
-		// validate ID
-		idRegex := regexp.MustCompile(VALID_ID_REGEX)
-		if !idRegex.MatchString(idStr) {
-			http.Error(w, "Bad 'id' URL parameter.", 400)
-			return
-		}
+	// get ID
+	ids := r.URL.Query()["id"]
+	if len(ids) != 1 {
+		http.Error(w, "Expected exactly one 'id' URL parameter.", 400)
+		return
+	}
+	idStr := ids[0]
 
-		// serve image
-		path := fmt.Sprintf("recipes/image/%s.jpg", idStr)
-		ServeStorage(w, r, storageRoot, path)
+	// validate ID
+	idRegex := regexp.MustCompile(VALID_ID_REGEX)
+	if !idRegex.MatchString(idStr) {
+		http.Error(w, "Bad 'id' URL parameter.", 400)
+		return
 	}
+
+	// serve image
+	path := fmt.Sprintf("recipes/image/%s.jpg", idStr)
+	ServeStorage(w, r, storage, path)
 }
 
-func add_recipes(db *Database, storageRoot string, staticRoot string) func(http.ResponseWriter, *http.Request) {
+func addRecipesGet(w http.ResponseWriter, r *http.Request, static string) {
 
-	return func(w http.ResponseWriter, r *http.Request) {
+	filename := "add.html"
+	path := filepath.Join(static, filename)
+	log.Printf("Trying to serve: %s", path)
+	http.ServeFile(w, r, path)
+}
 
-		if r.Method == "GET" {
-			filename := "add.html"
-			path := filepath.Join(staticRoot, filename)
-			log.Printf("Trying to serve: %s", path)
-			http.ServeFile(w, r, path)
-			return
-		}
+func addRecipesPost(w http.ResponseWriter, r *http.Request, db *Database) {
 
-		if r.Method == "POST" {
-			url := r.FormValue("url")
-			title := r.FormValue("title")
-
-			cmd := fmt.Sprintf("INSERT INTO recipes (title,upstream_url) VALUES ('%s', '%s')", title, url)
-			log.Println(cmd)
-			res,err := db.Backend.Exec(cmd)
-			if err != nil {
-				http.Error(w, "Could not add recipe.", 500)
-				return
-			}
-			id,err := res.LastInsertId()
-			if err != nil {
-				http.Error(w, "Expected exactly one recipe URL.", 400)
-				return
-			} else {
-				log.Println("Added custom recipe.")
-				redirect := fmt.Sprintf("/recipe?id=%d", id)
-				http.Redirect(w, r, redirect, 303)
-				return
-			}
-		}
+	url := r.FormValue("url")
+	title := r.FormValue("title")
+
+	cmd := fmt.Sprintf("INSERT INTO recipes (title,upstream_url) VALUES ('%s', '%s')", title, url)
+	log.Println(cmd)
+	res,err := db.Backend.Exec(cmd)
+	if err != nil {
+		http.Error(w, "Could not add recipe.", 500)
+		return
 	}
+	id,err := res.LastInsertId()
+	if err != nil {
+		http.Error(w, "Expected exactly one recipe URL.", 400)
+		return
+	} else {
+		log.Println("Added custom recipe.")
+		redirect := fmt.Sprintf("/recipe?id=%d", id)
+		http.Redirect(w, r, redirect, 303)
+		return
+	}
+}
+
+func staticGet(w http.ResponseWriter, r *http.Request, filename string, staticRoot string) {
+
+	path := filepath.Join(staticRoot, filename)
+	log.Printf("Trying to serve: %s\n", path)
+	http.ServeFile(w, r, path)
 }
diff --git a/mux.go b/mux.go
new file mode 100644
index 0000000..a351ade
--- /dev/null
+++ b/mux.go
@@ -0,0 +1,89 @@
+
+package main
+
+import (
+	"net/http"
+)
+
+func indexMux(db *Database, templateRoot string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			indexGet(w, r, db, templateRoot)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
+
+func recipeMux(db *Database, templateRoot string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			recipeGet(w, r, db, templateRoot)
+		case "POST":
+			recipePost(w, r, db)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
+
+func recipeEditMux(db *Database, templateRoot string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			recipeEditGet(w, r, db, templateRoot)
+		case "POST":
+			recipeEditPost(w, r, db)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
+
+func recipeImageMux(storage string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			recipeImageGet(w, r, storage)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
+
+func addRecipesMux(db *Database, storage string, static string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			addRecipesGet(w, r, static)
+		case "POST":
+			addRecipesPost(w, r, db)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
+
+func staticStyleMux(file string, static string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			staticGet(w, r, file, static)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
+
+func faviconMux(file string, static string) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			staticGet(w, r, file, static)
+		default:
+			http.Error(w, "Bad Request", 400)
+		}
+	}
+}
diff --git a/router.go b/router.go
index 508d23d..c1f5d78 100644
--- a/router.go
+++ b/router.go
@@ -6,31 +6,15 @@ import (
 	"net/http"
 )
 
-func indexMux(db *Database, templateRoot string) func(http.ResponseWriter, *http.Request) {
-	return func(w http.ResponseWriter, r *http.Request) {
-		switch r.Method {
-		case "GET":
-			indexGet(w, r, db, templateRoot)
-		default:
-			http.Error(w, "Bad Request", 400)
-		}
-	}
-}
-
 func RunServer(config HttpConfig, db *Database) {
 
 	http.HandleFunc("/", indexMux(db, config.Templates))
-
-	http.HandleFunc("/recipe", recipe(db, config.Templates))
-
-	http.HandleFunc("/recipe/edit", recipe_edit(db, config.Templates))
-
-	http.HandleFunc("/recipe/image", image(config.Storage))
-
-	http.HandleFunc("/add_recipes", add_recipes(db, config.Storage, config.Static))
-
-	http.HandleFunc("/static/style.css", static("style.css", config.Static))
-	http.HandleFunc("/favicon.ico", static("favicon.ico", config.Static))
+	http.HandleFunc("/recipe", recipeMux(db, config.Templates))
+	http.HandleFunc("/recipe/edit", recipeEditMux(db, config.Templates))
+	http.HandleFunc("/recipe/image", recipeImageMux(config.Storage))
+	http.HandleFunc("/add_recipes", addRecipesMux(db, config.Storage, config.Static))
+	http.HandleFunc("/static/style.css", staticStyleMux("style.css", config.Static))
+	http.HandleFunc("/favicon.ico", faviconMux("favicon.ico", config.Static))
 
 	address := config.Host + ":" + config.Port
 	log.Println("Binding to 'http://" + address)