feat: add a landing page for the Flow Platform

Add a landing page for the Flow Platform. The landing page is a
linktree-styled static page made with Go, HTML and CSS.

.gitattributes

@@ -0,0 +1,2 @@
+web/static/gpg/public.asc filter=lfs diff=lfs merge=lfs -text
+web/static/img/favicon.ico filter=lfs diff=lfs merge=lfs -text

.gitignore

@@ -0,0 +1 @@
+/landing

.golangci.yaml

@@ -18,5 +18,8 @@ linters-settings:
 
 linters:
   enable-all: true
-  # disable:
+  disable:
+  - exhaustruct
+  - exhaustivestruct
+  - gomnd
   fast: false

Dockerfile

@@ -0,0 +1,7 @@
+FROM scratch
+
+ADD landing /landing
+
+USER 65534
+
+ENTRYPOINT ["/landing"]

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 Dan Anglin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

go.mod

@@ -0,0 +1,5 @@
+module codeflow.dananglin.me.uk/flow/landing
+
+go 1.21.0
+
+require github.com/magefile/mage v1.15.0

go.sum

@@ -0,0 +1,2 @@
+github.com/magefile/mage v1.15.0 h1:BvGheCMAsG3bWUDbZ8AyXXpCNwU9u5CB6sM+HNb9HYg=
+github.com/magefile/mage v1.15.0/go.mod h1:z5UZb/iS3GoOSn0JgWuiw7dxlurVYTu+/jHXqQg881A=

links.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+type linkParseError struct {
+	msg string
+}
+
+func (e linkParseError) Error() string {
+	return "link parse error: " + e.msg
+}
+
+type link struct {
+	Title string
+	URL   string
+	Rel   string
+}
+
+func (l link) String() string {
+	return fmt.Sprintf("Title: %s, URL: %s, Rel: %s", l.Title, l.URL, l.Rel)
+}
+
+type links []link
+
+func (l *links) Set(value string) error {
+	linkAttributes := strings.Split(value, ",")
+
+	lenLinkAttributes := len(linkAttributes)
+	if lenLinkAttributes != 2 && lenLinkAttributes != 3 {
+		return linkParseError{msg: fmt.Sprintf("unexpected number of attributes found %s, want 2 or 3, got %d", value, lenLinkAttributes)}
+	}
+
+	var thisLink link
+
+	for _, attr := range linkAttributes {
+		split := strings.Split(attr, "=")
+		switch strings.ToLower(split[0]) {
+		case "title":
+			thisLink.Title = split[1]
+		case "url":
+			thisLink.URL = split[1]
+		case "rel":
+			thisLink.Rel = split[1]
+		}
+	}
+
+	if thisLink.Title == "" {
+		return linkParseError{msg: fmt.Sprintf("the title attribute is missing from %s", value)}
+	}
+
+	if thisLink.URL == "" {
+		return linkParseError{msg: fmt.Sprintf("the URL attribute is missing from %s", value)}
+	}
+
+	*l = append(*l, thisLink)
+
+	return nil
+}
+
+func (l *links) String() string {
+	if len(*l) == 0 {
+		return ""
+	}
+
+	var builder strings.Builder
+
+	for _, link := range *l {
+		fmt.Fprintln(&builder, link)
+	}
+
+	return builder.String()
+}

magefiles/mage.go

@@ -11,7 +11,7 @@ import (
 
 var Default = Build
 
-var binary = "app"
+var binary = "landing"
 
 // Test run the go tests.
 // To enable verbose mode set GO_TEST_VERBOSE=1.
@@ -39,8 +39,7 @@ func Lint() error {
 
 // Build build the executable.
 func Build() error {
-	main := "main.go"
-	return sh.Run("go", "build", "-o", binary, main)
+	return sh.Run("go", "build", "-o", binary, ".")
 }
 
 // Clean clean the workspace.

main.go

@@ -1,4 +1,144 @@
 package main
 
+import (
+	"embed"
+	"flag"
+	"fmt"
+	"html/template"
+	"io/fs"
+	"log/slog"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+)
+
+//go:embed web/static/*
+var staticFS embed.FS
+
+//go:embed web/html/*
+var htmlTemplates embed.FS
+
 func main() {
+	var (
+		address  string
+		profiles links
+		services links
+	)
+
+	flag.StringVar(&address, "address", "0.0.0.0:8080", "The address that the web server will listen on")
+	flag.Var(&services, "service", "A list of service links")
+	flag.Var(&profiles, "profile", "A list of profile links")
+
+	flag.Parse()
+
+	setupLogging()
+
+	mux, err := routes(services, profiles)
+	if err != nil {
+		slog.Error("Unable to create the Mux", "error", err)
+		os.Exit(1)
+	}
+
+	server := http.Server{
+		Addr:              address,
+		Handler:           mux,
+		ReadHeaderTimeout: 1 * time.Second,
+		ReadTimeout:       5 * time.Second,
+	}
+
+	slog.Info("Starting web application.", "address", address)
+
+	err = server.ListenAndServe()
+	if err != nil {
+		slog.Error("Failed to run the web application", "error", err)
+	}
+}
+
+func routes(services, profiles links) (*http.ServeMux, error) {
+	mux := http.NewServeMux()
+
+	staticRootFS, err := fs.Sub(staticFS, "web/static")
+	if err != nil {
+		return nil, fmt.Errorf("unable to create the static root file system; %w", err)
+	}
+
+	fileServer := http.FileServer(http.FS(staticRootFS))
+	mux.Handle("/static/", http.StripPrefix("/static", neuter(fileServer)))
+
+	mux.HandleFunc("/", landing(services, profiles))
+
+	return mux, nil
+}
+
+func neuter(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		if strings.HasSuffix(request.URL.Path, "/") {
+			notFound(writer)
+
+			return
+		}
+
+		next.ServeHTTP(writer, request)
+	})
+}
+
+func landing(services, profiles links) func(http.ResponseWriter, *http.Request) {
+	return func(writer http.ResponseWriter, request *http.Request) {
+		if request.URL.Path != "/" {
+			notFound(writer)
+
+			return
+		}
+
+		if request.Method != http.MethodGet {
+			writer.Header().Set("Allow", http.MethodGet)
+			clientError(writer, http.StatusMethodNotAllowed)
+
+			return
+		}
+
+		tmpl, err := template.New("base").ParseFS(htmlTemplates, "web/html/base.tmpl.html")
+		if err != nil {
+			serverError(writer, fmt.Errorf("error parsing the HTML template; %w", err))
+
+			return
+		}
+
+		links := struct {
+			Services links
+			Profiles links
+		}{
+			Services: services,
+			Profiles: profiles,
+		}
+
+		if err = tmpl.Execute(writer, &links); err != nil {
+			serverError(writer, fmt.Errorf("error rendering the HTML templates; %w", err))
+		}
+	}
+}
+
+func notFound(w http.ResponseWriter) {
+	clientError(w, http.StatusNotFound)
+}
+
+func clientError(w http.ResponseWriter, status int) {
+	http.Error(w, http.StatusText(status), status)
+}
+
+func serverError(w http.ResponseWriter, err error) {
+	slog.Error(err.Error())
+
+	http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+}
+
+func setupLogging() {
+	opts := slog.HandlerOptions{
+		AddSource: false,
+	}
+
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, &opts))
+
+	slog.SetDefault(logger)
 }

web/html/base.tmpl.html

@@ -0,0 +1,31 @@
+{{ define "base" }}
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>Dan Anglin | Flow Platform</title>
+    <link rel="stylesheet" href="/static/css/stylesheet.css">
+    <link rel="icon" type="image/x-icon" href="/static/img/favicon.ico">
+</head>
+
+<body>
+    <h1>Flow Platform</h1>
+    {{ if gt (len .Services) 0 }}
+    <h2>Services</h2>
+    <div class="links">
+        {{- range .Services }}
+        <p><a href="{{ .URL }}"{{ if gt (len .Rel) 0 }} rel="{{ .Rel }}"{{ end }}>{{ .Title }}</a></p>
+        {{ end }}
+    </div>
+    {{ end }}
+    {{ if gt (len .Profiles) 0 }}
+    <h2>My Profiles</h2>
+    <div class="links">
+        {{- range .Profiles }}
+        <p><a href="{{ .URL }}"{{ if gt (len .Rel) 0 }} rel="{{ .Rel }}"{{ end }}>{{ .Title }}</a></p>
+        {{ end }}
+    </div>
+    {{ end }}
+</body>
+</html>
+{{ end }}

web/static/css/stylesheet.css

@@ -0,0 +1,33 @@
+body {
+    background-color: #1e1c31;
+    text-align: center;
+    font-family: sans-serif;
+    font-weight: 600;
+}
+
+h1, h2{
+    color: white;
+}
+
+body .links {
+    max-width: 500px; 
+    margin: auto;
+    text-align: center;
+}
+
+body .links p a {
+    display: block;
+    background-color: #296ae2;
+    color: Thistle;
+    text-decoration: none;
+    padding: 15px;
+    margin-bottom: 10px;
+    transition: 0.5s;
+    border-radius: 5px;
+}
+
+body .links p a:hover, a:active {
+    background-color: #719dee;
+    color: White;
+    transition: 0.5s;
+}