Add redirects table and simple redirect functionality

database_migrations.go

@@ -17,6 +17,13 @@ func migrateDb() error {
 					return err
 				},
 			},
+			&migrator.Migration{
+				Name: "00002",
+				Func: func(tx *sql.Tx) error {
+					_, err := tx.Exec("create table redirects (fromPath text not null, toPath text not null, primary key (fromPath, toPath));")
+					return err
+				},
+			},
 		),
 	)
 	if err != nil {

http.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"os/signal"
 	"strconv"
+	"strings"
 	"sync"
 	"syscall"
 	"time"
@@ -62,7 +63,18 @@ func buildHandler() (http.Handler, error) {
 	} else {
 		for _, path := range allPostPaths {
 			if path != "" {
-				r.Get(path, servePost)
+				r.With(TrimSlash).Get(path, servePost)
+			}
+		}
+	}
+
+	allRedirectPaths, err := allRedirectPaths()
+	if err != nil {
+		return nil, err
+	} else {
+		for _, path := range allRedirectPaths {
+			if path != "" {
+				r.With(TrimSlash).Get(path, serveRedirect)
 			}
 		}
 	}
@@ -90,3 +102,12 @@ func (d *dynamicHandler) swapHandler(h http.Handler) {
 func (d *dynamicHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	d.realHandler.ServeHTTP(w, r)
 }
+
+func TrimSlash(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if len(r.RequestURI) > 1 {
+			r.RequestURI = strings.TrimSuffix(r.RequestURI, "/")
+		}
+		next.ServeHTTP(w, r)
+	})
+}

posts.go

@@ -5,7 +5,6 @@ import (
 	"database/sql"
 	"errors"
 	"net/http"
-	"strings"
 )
 
 var postNotFound = errors.New("post not found")
@@ -18,11 +17,7 @@ type post struct {
 }
 
 func servePost(w http.ResponseWriter, r *http.Request) {
-	path := r.RequestURI
-	if len(path) > 1 {
-		path = strings.TrimSuffix(path, "/")
-	}
-	post, err := getPost(path, r.Context())
+	post, err := getPost(r.RequestURI, r.Context())
 	if err == postNotFound {
 		http.NotFound(w, r)
 		return

redirects.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"net/http"
+)
+
+var redirectNotFound = errors.New("redirect not found")
+
+type redirect struct {
+	fromPath string
+	toPath   string
+}
+
+func serveRedirect(w http.ResponseWriter, r *http.Request) {
+	redirect, err := getRedirect(r.RequestURI, r.Context())
+	if err == redirectNotFound {
+		http.NotFound(w, r)
+		return
+	} else if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	// TODO: Change status code
+	http.Redirect(w, r, redirect, http.StatusTemporaryRedirect)
+}
+
+func getRedirect(fromPath string, context context.Context) (string, error) {
+	var toPath string
+	row := appDb.QueryRowContext(context, "select toPath from redirects where fromPath=?", fromPath)
+	err := row.Scan(&toPath)
+	if err == sql.ErrNoRows {
+		return "", redirectNotFound
+	} else if err != nil {
+		return "", err
+	}
+	return toPath, nil
+}
+
+func allRedirectPaths() ([]string, error) {
+	var redirectPaths []string
+	rows, err := appDb.Query("select fromPath from redirects")
+	if err != nil {
+		return nil, err
+	}
+	for rows.Next() {
+		var path string
+		_ = rows.Scan(&path)
+		redirectPaths = append(redirectPaths, path)
+	}
+	return redirectPaths, nil
+}