tests are good

main.go

@@ -45,13 +45,33 @@ func (h Handler) serveHTTP(w http.ResponseWriter, r *http.Request) error {
 		return err
 	}
 
+	var duplicate int
+	if err := h.idempotency.QueryRowContext(r.Context(), `SELECT 1 FROM payloads WHERE payload=$1;`, b).Scan(&duplicate); err != sql.ErrNoRows && err != nil {
+		log.Println("!", err)
+	} else if duplicate > 0 {
+		log.Println("+")
+		return nil
+	}
+
+	if err := h.prune(time.Now().Add(-1 * time.Hour * 24 * 7)); err != nil {
+		log.Println("!", err)
+	}
+
 	resp, err := proxy(h.target, r, io.NopCloser(bytes.NewReader(b)))
 	if err != nil {
 		return err
 	}
 	defer resp.Body.Close()
 
-	return forward(w, resp)
+	if err := forward(w, resp); err != nil {
+		return err
+	}
+
+	if _, err := h.idempotency.ExecContext(r.Context(), `INSERT INTO payloads (ts, payload) VALUES ($1, $2);`, time.Now(), b); err != nil {
+		log.Println("!", err)
+	}
+
+	return nil
 }
 
 func main() {
@@ -63,40 +83,47 @@ func main() {
 	if err := fs.Parse(os.Args[1:]); err != nil {
 		panic(err)
 	}
+	if err := run(*p, *t, *y, *db); err != nil {
+		panic(err)
+	}
+}
 
-	db, err := sql.Open("sqlite", *db)
+func run(p int, t string, y string, db string) error {
+	idempotency, err := sql.Open("sqlite", db)
 	if err != nil {
-		panic(err)
+		return err
 	}
-	defer db.Close()
-	if err := db.PingContext(context.Background()); err != nil {
-		panic(err)
+	defer idempotency.Close()
+	if err := idempotency.PingContext(context.Background()); err != nil {
+		return err
+	} else if _, err := idempotency.ExecContext(context.Background(), `CREATE TABLE IF NOT EXISTS payloads (payload TEXT, ts TIMESTAMP NOT NULL)`); err != nil {
+		return err
 	}
 
-	tmpl, err := template.New("").Parse(*t)
+	tmpl, err := template.New("").Parse(t)
 	if err != nil {
-		panic(err)
+		return err
 	}
 
-	u, err := url.Parse(*y)
+	u, err := url.Parse(y)
 	if err != nil {
-		panic(err)
+		return err
 	}
 
-	h := Handler{tmpl: tmpl, target: u, idempotency: db}
-	log.Println("listening on", *p)
-	if err := http.ListenAndServe(":"+strconv.Itoa(*p), h); err != nil {
-		panic(err)
-	}
+	h := Handler{tmpl: tmpl, target: u, idempotency: idempotency}
+	log.Println("listening on", p)
+	return http.ListenAndServe(":"+strconv.Itoa(p), h)
 }
 
 func adapt(r io.Reader, tmpl *template.Template) ([]byte, error) {
 	b, _ := io.ReadAll(io.LimitReader(r, 1024*1024))
 	var v interface{}
 	buff := bytes.NewBuffer(nil)
-	if err := json.Unmarshal(b, &v); err != nil {
+	if len(b) == 0 {
+	} else if err := json.Unmarshal(b, &v); err != nil {
 		return nil, err
-	} else if err := tmpl.Execute(buff, v); err != nil {
+	}
+	if err := tmpl.Execute(buff, v); err != nil {
 		return nil, err
 	}
 	log.Printf("%s => %s", b, buff.Bytes())
@@ -135,3 +162,17 @@ func forward(w http.ResponseWriter, resp *http.Response) error {
 	io.Copy(w, resp.Body)
 	return nil
 }
+
+func (h Handler) prune(ts time.Time) error {
+	result, err := h.idempotency.ExecContext(context.Background(), `DELETE FROM payloads WHERE ts < $1;`, ts)
+	if err != nil {
+		return err
+	}
+
+	rows, _ := result.RowsAffected()
+	if rows > 1 {
+		log.Println("-", rows)
+	}
+
+	return nil
+}

main_test.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"path"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestRun(t *testing.T) {
+	targetCalls := 0
+	target := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		targetCalls += 1
+	}))
+	defer target.Close()
+
+	p := func() int {
+		s := httptest.NewServer(http.HandlerFunc(http.NotFound))
+		s.Close()
+		u := s.URL
+		ps := strings.Split(u, ":")[2]
+		n, err := strconv.Atoi(ps)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return n
+	}()
+	tmpl := `{{ . }}`
+	x := fmt.Sprintf(`http://localhost:%d`, p)
+	y := target.URL
+	db := path.Join(t.TempDir(), "db")
+
+	do := func(method, body string) bool {
+		req, _ := http.NewRequest(method, x, strings.NewReader(body))
+		resp, err := httpc.Do(req)
+		if err != nil {
+			return false
+		}
+		resp.Body.Close()
+		return true
+	}
+
+	go func() {
+		if err := run(p, tmpl, y, db); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	for !do(http.MethodGet, "") {
+		time.Sleep(time.Millisecond * 100)
+	}
+
+	if targetCalls != 1 {
+		t.Error("empty req body no called target")
+	}
+
+	if !do(http.MethodGet, "") {
+		t.Error("couldnt get a second time with no body")
+	} else if targetCalls != 1 {
+		t.Error("no dedupe no body")
+	}
+
+	if !do(http.MethodPost, "1") {
+		t.Error("couldnt get a third time with new body")
+	} else if targetCalls != 2 {
+		t.Error("deduped new body")
+	} else if !do(http.MethodPost, "1") {
+		t.Error("couldnt get a fourth time with new body again")
+	} else if targetCalls != 2 {
+		t.Error("no deduped new body again")
+	} else if !do(http.MethodPost, "2") {
+		t.Error("couldnt get a fifth time with new new body")
+	} else if targetCalls != 3 {
+		t.Error("deduped new new body")
+	}
+}