add csv reading, routing

internal/cli.go

@@ -0,0 +1,7 @@
+package internal
+
+type CLI struct {
+	File string `arg:"" name:"file" short:"f" help:"Path to CSV redirects file." type:"path"`
+	Host string `name:"host" help:"HTTP listen host." default:"${host}"`
+	Port string `name:"port" short:"p" help:"HTTP listen port." default:"${port}"`
+}

internal/csv.go

@@ -0,0 +1,72 @@
+package internal
+
+import (
+	"encoding/csv"
+	"errors"
+	"io"
+	"os"
+	"strconv"
+)
+
+type Headings []string
+
+func (h Headings) IndexOf(heading string) int {
+	for i, value := range h {
+		if value == heading {
+			return i
+		}
+	}
+
+	return -1
+}
+
+func ReadCsvRedirects(file string) (Redirects, error) {
+	reader, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+
+	csvReader := csv.NewReader(reader)
+
+	// Process headings
+	textHeadings, err := csvReader.Read()
+	if err != nil {
+		return nil, err
+	}
+	headings := Headings(textHeadings)
+	fromCol := headings.IndexOf("From")
+	toCol := headings.IndexOf("To")
+	statusCol := headings.IndexOf("Status Code")
+	if fromCol == -1 || toCol == -1 || statusCol == -1 {
+		return nil, errors.New("CSV must contain From, To, and Status Code headings")
+	}
+
+	redirects := Redirects{}
+	for {
+		row, err := csvReader.Read()
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				break
+			}
+			return nil, err
+		}
+		if row == nil {
+			break
+		}
+
+		statusCode, err := strconv.Atoi(row[statusCol])
+		if err != nil {
+			return nil, err
+		}
+
+		redirect := &Redirect{
+			From:       row[fromCol],
+			To:         row[toCol],
+			StatusCode: statusCode,
+		}
+
+		redirects = append(redirects, redirect)
+	}
+
+	return redirects, nil
+}

internal/http.go

@@ -0,0 +1,26 @@
+package internal
+
+import (
+	"net/http"
+
+	"github.com/rs/zerolog"
+)
+
+type HttpServer struct {
+	CLI       *CLI
+	Log       zerolog.Logger
+	Redirects Redirects
+}
+
+func (srv *HttpServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	redirect := srv.Redirects.Find(req.URL.Path)
+	if redirect != nil {
+		srv.Log.Info().Int("result", redirect.StatusCode).Msg(req.URL.Path)
+		w.WriteHeader(redirect.StatusCode)
+		w.Header().Add("location", redirect.To)
+	} else {
+		statusCode := 404
+		srv.Log.Error().Int("result", statusCode).Msg(req.URL.Path)
+		w.WriteHeader(statusCode)
+	}
+}

internal/redirect.go

@@ -0,0 +1,24 @@
+package internal
+
+type Redirect struct {
+	From       string
+	To         string
+	StatusCode int
+}
+
+func (r *Redirect) Match(from string) bool {
+	return from == r.From
+}
+
+type Redirects []*Redirect
+
+func (rs Redirects) Find(from string) *Redirect {
+	for i := 0; i < len(rs); i++ {
+		redirect := rs[i]
+		if redirect.Match(from) {
+			return redirect
+		}
+	}
+
+	return nil
+}

main.go

@@ -6,37 +6,27 @@ import (
 
 	"github.com/alecthomas/kong"
 	"github.com/rs/zerolog"
+	"gogs.home.aneur.in/go/ultrashorty/internal"
 )
 
-type CLI struct {
-	File string `arg:"" name:"file" short:"f" help:"Path to CSV redirects file." type:"path"`
-	Host string `name:"host" help:"HTTP listen host." default:"${host}"`
-	Port string `name:"port" short:"p" help:"HTTP listen port." default:"${port}"`
-}
-
-type HttpServer struct {
-	CLI *CLI
-	Log zerolog.Logger
-}
-
-func (srv *HttpServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	statusCode := 404
-	srv.Log.Trace().Int("result", statusCode).Msg(req.URL.Path)
-	w.WriteHeader(statusCode)
-}
-
 func main() {
 	vars := kong.Vars{
 		"host": "localhost",
 		"port": "4000",
 	}
 
-	cli := &CLI{}
+	cli := &internal.CLI{}
 	kong.Parse(cli, vars)
 
-	srv := &HttpServer{
+	redirects, err := internal.ReadCsvRedirects(cli.File)
+	if err != nil {
+		panic(err)
+	}
+
+	srv := &internal.HttpServer{
 		CLI:       cli,
 		Log:       zerolog.New(zerolog.NewConsoleWriter()).With().Timestamp().Logger(),
+		Redirects: redirects,
 	}
 
 	addr := net.JoinHostPort(cli.Host, cli.Port)
@@ -46,6 +36,6 @@ func main() {
 	}()
 
 	srv.Log.Info().Msgf("Listening at %s", addr)
-	err := <-errc
+	err = <-errc
 	panic(err)
 }