adds html template support to web package (#5)

README.md

@@ -4,7 +4,7 @@ A kitchen sink of Go tools that I've found useful. Uses only the standard librar
 
 ### contents
 
-- [super lightweight http server framework](web)
+- [super lightweight http server library](web)
 - [exponential backoff retry](retry.go)
 - [working with JSON](json.go)
 - [working with the file system](fs.go)
@@ -53,27 +53,48 @@ func main() {
 	if err != nil {
 		fmt.Println("error executing command: %w", err)
 	}
+
+	var data interface{}
+	err = gotoolbox.HttpGetJSON("https://api.example.com/data.json", &data)
+	err = gotoolbox.HttpPostJSON("https://api.example.com/data.json", data, http.StatusOK)
 }
 ```
 
-#### web framework
+#### web package
 
 ```go
 package main
 
-import "github.com/jritsema/gotoolbox/web"
+import (
+	"embed"
+	"html/template"
+	"net/http"
+	"github.com/jritsema/gotoolbox/web"
+)
+
+var (
+	//go:embed all:templates/*
+	templateFS embed.FS
+	html *template.Template
+)
 
 type Data struct {
 	Hello string `json:"hello"`
 }
 
-func hello(r *http.Request) *web.Response {
+func index(r *http.Request) *web.Response {
+	return HTML(http.StatusOK, html, "index.html", Data{Hello: "world"}, nil)
+}
+
+func api(r *http.Request) *web.Response {
 	return web.DataJSON(http.StatusOK, Data{Hello: "world"}, nil)
 }
 
 func main() {
+	html, _ = web.TemplateParseFSRecursive(templateFS, ".html", true, nil)
 	mux := http.NewServeMux()
-	mux.Handle("/hello", web.Action(hello))
+	mux.Handle("/api", web.Action(api))
+	mux.Handle("/", web.Action(index))
 	http.ListenAndServe(":8080", mux)
 }
 ```

web/main.go

@@ -1,11 +1,16 @@
-//Package web is a super minimalistic web/http server framework
+// Package web is a super minimalistic web/http server library
 package web
 
 import (
 	"bytes"
 	"encoding/json"
+	"html/template"
 	"io"
+	"io/fs"
+	"log"
 	"net/http"
+	"os"
+	"strings"
 )
 
 // Headers is a map of string to string where the key is the key for the header
@@ -24,7 +29,7 @@ type Response struct {
 	Headers Headers
 }
 
-//Write writes a response to an http.ResponseWriter
+// Write writes a response to an http.ResponseWriter
 func (response *Response) Write(rw http.ResponseWriter) {
 	if response != nil {
 		if response.ContentType != "" {
@@ -45,7 +50,7 @@ func (response *Response) Write(rw http.ResponseWriter) {
 }
 
 // Action represents a simplified http action
-// implements http.Handler
+// that implements http.Handler
 type Action func(r *http.Request) *Response
 
 // Hyperlink represents a hyperlink
@@ -60,7 +65,7 @@ func (a Action) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 	response.Write(rw)
 }
 
-//Error returns an error response
+// Error returns an error response
 func Error(status int, err error, headers Headers) *Response {
 	return &Response{
 		Status:  status,
@@ -73,7 +78,7 @@ type errorResponse struct {
 	Error string `json:"error"`
 }
 
-//ErrorJSON returns an error in json format
+// ErrorJSON returns an error in json format
 func ErrorJSON(status int, err error, headers Headers) *Response {
 	errResp := errorResponse{
 		Error: err.Error(),
@@ -92,7 +97,7 @@ func ErrorJSON(status int, err error, headers Headers) *Response {
 	}
 }
 
-//Data returns a data response
+// Data returns a data response
 func Data(status int, content []byte, headers Headers) *Response {
 	return &Response{
 		Status:  status,
@@ -101,7 +106,7 @@ func Data(status int, content []byte, headers Headers) *Response {
 	}
 }
 
-//DataJSON returns a data response in json format
+// DataJSON returns a data response in json format
 func DataJSON(status int, v interface{}, headers Headers) *Response {
 
 	b, err := json.MarshalIndent(v, "", "  ")
@@ -117,7 +122,76 @@ func DataJSON(status int, v interface{}, headers Headers) *Response {
 	}
 }
 
-//Empty returns an empty http response
+// Empty returns an empty http response
 func Empty(status int) *Response {
 	return Data(status, []byte(""), nil)
 }
+
+// HTML renders an html template to a web response
+func HTML(status int, t *template.Template, template string, data interface{}, headers Headers) *Response {
+
+	//render template to buffer
+	var buf bytes.Buffer
+	if err := t.ExecuteTemplate(&buf, template, data); err != nil {
+		log.Println(err)
+		return Empty(http.StatusInternalServerError)
+	}
+	return &Response{
+		Status:      status,
+		ContentType: "text/html",
+		Content:     &buf,
+		Headers:     headers,
+	}
+}
+
+// TemplateParseFSRecursive recursively parses all templates in the FS with the given extension.
+// File paths are used as template names to support duplicate file names.
+// Use nonRootTemplateNames to exclude root directory from template names
+// (e.g. index.html instead of templates/index.html)
+func TemplateParseFSRecursive(
+	templates fs.FS,
+	ext string,
+	nonRootTemplateNames bool,
+	funcMap template.FuncMap) (*template.Template, error) {
+
+	root := template.New("")
+	err := fs.WalkDir(templates, "templates", func(path string, d fs.DirEntry, err error) error {
+		if !d.IsDir() && strings.HasSuffix(path, ext) {
+			if err != nil {
+				return err
+			}
+			b, err := fs.ReadFile(templates, path)
+			if err != nil {
+				return err
+			}
+			name := ""
+			if nonRootTemplateNames {
+				//name the template based on the file path (excluding the root)
+				parts := strings.Split(path, string(os.PathSeparator))
+				name = strings.Join(parts[1:], string(os.PathSeparator))
+			}
+			t := root.New(name).Funcs(funcMap)
+			_, err = t.Parse(string(b))
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	return root, err
+}
+
+// PathLast returns the last segment in the path
+// and the number of path segments
+func PathLast(r *http.Request) (string, int) {
+
+	//remove trailing /
+	path := r.URL.Path
+	if path[len(path)-1] == '/' {
+		path = path[0 : len(path)-1]
+	}
+
+	parts := strings.Split(path, "/")
+	l := len(parts) - 1
+	return parts[l], l
+}