added genString

http/server.go

@@ -1,20 +1,26 @@
 package main
 
 import (
+	"bytes"
+	"crypto/rand"
 	"fmt"
 	"io"
 	"log"
+	"math/big"
 	"net/http"
 	"time"
 
 	h "gitlab.codemonkeysoftware.net/b/hatmill"
 	a "gitlab.codemonkeysoftware.net/b/hatmill/attribute"
 	e "gitlab.codemonkeysoftware.net/b/hatmill/element"
+	"gitlab.codemonkeysoftware.net/b/henwen"
 	_ "gitlab.codemonkeysoftware.net/b/henwen"
 )
 
 const Addr = ":8080"
 const Title = "Henwen"
+const baseURL = "http://localhost:8080"
+const dbFileName = "./henwen.db"
 
 const (
 	PathRoot     = "/"
@@ -22,6 +28,8 @@ const (
 	PathDoCreate = "/create/do"
 )
 
+var store *henwen.Store
+
 func writePage(w io.Writer, contents h.Term) error {
 	page := e.Html()(
 		e.Head()(
@@ -69,9 +77,28 @@ func pageCreate() h.Term {
 	}
 }
 
+func makeAdminURL(eventID, adminCode string) string {
+	return fmt.Sprintf("%s/%s/admin/%s", baseURL, eventID, adminCode)
+}
+
 func pageDoCreate(name string, earliest, latest time.Time) h.Term {
+	id, err := genString()
+	if err != nil {
+		return h.Text(err.Error())
+	}
+	adminCode, err := genString()
+	if err != nil {
+		return h.Text(err.Error())
+	}
+	adminURL := makeAdminURL(id, adminCode)
+
 	return h.Terms{
 		e.H2()(h.Text("Created event!")),
+		e.P()(
+			h.Text("You can find it again at "),
+			e.A(a.Href(adminURL))(h.Text(adminURL)),
+			h.Text("."),
+		),
 
 		e.H3()(h.Text("Name")),
 		h.Text(name),
@@ -84,6 +111,27 @@ func pageDoCreate(name string, earliest, latest time.Time) h.Term {
 	}
 }
 
+var chars = []byte("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+func genString() (string, error) {
+	const length = 10
+	charsLength := big.NewInt(int64(len(chars)))
+	var maxN big.Int
+	maxN.Exp(charsLength, big.NewInt(length), nil)
+	n, err := rand.Int(rand.Reader, &maxN)
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	for n.Cmp(&big.Int{}) == 1 {
+		var charIdx big.Int
+		n.DivMod(n, charsLength, &charIdx)
+		_ = buf.WriteByte(chars[charIdx.Int64()])
+	}
+	return buf.String(), nil
+}
+
 func main() {
 	mux := http.NewServeMux()
 	mux.HandleFunc(PathRoot, func(w http.ResponseWriter, r *http.Request) {