generic: net return full response struct

This is still quite easy to stub, and the extra information is very
useful to the caller.

Signed-off-by: Yonah <contrib@gensokyo.uk>

.gitignore

@@ -10,6 +10,7 @@
 
 # Content-addressed media files
 /data
+/data0
 
 # Test binary, built with `go test -c`
 *.test

album.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"net/http"
 	"os"
 )
 
@@ -108,13 +109,16 @@ func (a *Album) Enrich(ctx context.Context, n Net) error {
 	}
 
 	var v AlbumResponse
-	if body, _, err := n.Get(ctx, APIPrefix+"/album/"+a.CID.String()+"/detail"); err != nil {
+	u := APIPrefix + "/album/" + a.CID.String() + "/detail"
+	if resp, err := n.Get(ctx, u); err != nil {
 		return err
+	} else if resp.StatusCode != http.StatusOK {
+		return &ResponseStatusError{u, resp.StatusCode, resp.Body.Close()}
 	} else {
-		if err = json.NewDecoder(body).Decode(&v); err != nil {
-			return errors.Join(body.Close(), err)
+		if err = json.NewDecoder(resp.Body).Decode(&v); err != nil {
+			return errors.Join(resp.Body.Close(), err)
 		}
-		if err = body.Close(); err != nil {
+		if err = resp.Body.Close(); err != nil {
 			return err
 		}
 	}

album_test.go

@@ -183,6 +183,19 @@ func TestAlbumEnrich(t *testing.T) {
 			makeAlbumPath(1030, true): []byte{0},
 		}, Album{}, errors.Join(newSyntaxError("invalid character '\\x00' looking for beginning of value", 1))},
 
+		{"status", Album{
+			CID:      1030,
+			Name:     "Speed of Light",
+			CoverURL: "https://web.hycdn.cn/siren/pic/20210322/56cbcd1d0093d8ee8ee22bf6d68ab4a6.jpg",
+			Artists:  []string{"塞壬唱片-MSR", "DJ Okawari"},
+		}, stubNetErrorCloser{
+			makeAlbumPath(1030, true): []byte{0xde, 0xad, 0xbe, 0xef},
+		}, Album{}, &ResponseStatusError{
+			URL:        "https://monster-siren.hypergryph.com/api/album/1030/detail",
+			StatusCode: 0xdeadbeef,
+			CloseErr:   os.ErrInvalid,
+		}},
+
 		{"close", Album{
 			CID:      1030,
 			Name:     "Speed of Light",

cmd/msrfetch/fetch.go

@@ -8,6 +8,7 @@ import (
 	"flag"
 	"io"
 	"log"
+	"net/http"
 	"os"
 	"path"
 	"slices"
@@ -97,19 +98,21 @@ func mustFetch(ctx context.Context) {
 			defer wg.Done()
 			for u := range uc {
 				buf := new(bytes.Buffer)
-				if r, l, err := n.Get(ctx, u); err != nil {
+				if resp, err := n.Get(ctx, u); err != nil {
 					log.Fatal(err)
+				} else if resp.StatusCode != http.StatusOK {
+					log.Fatal(&monstersirenfetch.ResponseStatusError{URL: u, StatusCode: resp.StatusCode, CloseErr: resp.Body.Close()})
 				} else {
-					if v := int(l); v > 0 {
+					if v := int(resp.ContentLength); v > 0 {
 						buf.Grow(v)
 					}
-					if _, err = io.Copy(buf, r); err != nil {
-						if closeErr := r.Close(); closeErr != nil {
+					if _, err = io.Copy(buf, resp.Body); err != nil {
+						if closeErr := resp.Body.Close(); closeErr != nil {
 							log.Print(closeErr)
 						}
 						log.Fatal(err)
 					}
-					if err = r.Close(); err != nil {
+					if err = resp.Body.Close(); err != nil {
 						log.Fatal(err)
 					}
 				}

cmd/msrfetch/net.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"io"
 	"net/http"
 )
 
@@ -10,12 +9,12 @@ type netDirect struct {
 	c http.Client
 }
 
-func (n *netDirect) Get(ctx context.Context, url string) (io.ReadCloser, int64, error) {
+func (n *netDirect) Get(ctx context.Context, url string) (*http.Response, error) {
 	var resp *http.Response
 	if req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil); err != nil {
-		return nil, -2, err
+		return nil, err
 	} else if resp, err = n.c.Do(req); err != nil {
-		return nil, -2, err
+		return nil, err
 	}
-	return resp.Body, resp.ContentLength, nil
+	return resp, nil
 }

generic.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/http"
 	"strconv"
 	"strings"
 )
@@ -30,7 +31,21 @@ func (e *InconsistentEnrichError[T]) Error() string {
 type Net interface {
 	// Get makes a get request to url and returns the response body.
 	// The caller must close the body after it finishes reading from it.
-	Get(ctx context.Context, url string) (body io.ReadCloser, contentLength int64, err error)
+	Get(ctx context.Context, url string) (resp *http.Response, err error)
+}
+
+// ResponseStatusError is returned when MSR responds with a StatusCode other than [http.StatusOK].
+type ResponseStatusError struct {
+	// URL is the full uninterpreted url string for this request.
+	URL string
+	// StatusCode holds the [http.Response] field of the same name.
+	StatusCode int
+	// CloseErr holds the error returned closing the response body.
+	CloseErr error
+}
+
+func (e *ResponseStatusError) Error() string {
+	return e.URL + " responded with status code " + strconv.Itoa(e.StatusCode)
 }
 
 // Metadata represents metadata, often enriched, of the entire website.

generic_test.go

@@ -6,9 +6,11 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/http"
 	"os"
 	"reflect"
 	"strconv"
+	"strings"
 	"testing"
 	"unsafe"
 
@@ -22,6 +24,13 @@ func TestInconsistentEnrichError(t *testing.T) {
 	}
 }
 
+func TestResponseStatusError(t *testing.T) {
+	const want = "/proc/nonexistent responded with status code 404"
+	if got := (&ResponseStatusError{URL: "/proc/nonexistent", StatusCode: http.StatusNotFound, CloseErr: os.ErrInvalid}).Error(); got != want {
+		t.Errorf("Error: %q, want %q", got, want)
+	}
+}
+
 func TestNullableString(t *testing.T) {
 	checkJSONRoundTripM(t, []jsonRoundTripTestCase[NullableString]{
 		{"zero", nil, `null`, ""},
@@ -116,21 +125,25 @@ func checkJSONRoundTrip[T any](t *testing.T, v T, data []byte) {
 
 type stubNetErrorCloser stubNet
 
-func (n stubNetErrorCloser) Get(ctx context.Context, url string) (io.ReadCloser, int64, error) {
-	r, l, err := stubNet(n).Get(ctx, url)
-	if r != nil {
-		r = errorCloser{r}
+func (n stubNetErrorCloser) Get(ctx context.Context, url string) (*http.Response, error) {
+	resp, err := stubNet(n).Get(ctx, url)
+	if resp != nil && resp.Body != nil {
+		resp.Body = errorCloser{resp.Body}
 	}
-	return r, l, err
+	return resp, err
 }
 
 type stubNet map[string][]byte
 
-func (n stubNet) Get(_ context.Context, url string) (io.ReadCloser, int64, error) {
+func (n stubNet) Get(_ context.Context, url string) (*http.Response, error) {
 	if b, ok := n[url]; !ok {
-		return nil, -2, fmt.Errorf("url %s requested, but is not present", url)
+		return nil, fmt.Errorf("url %s requested, but is not present", url)
+	} else if string(b) == "\xde\xad\xbe\xef" {
+		return &http.Response{StatusCode: 0xdeadbeef, ContentLength: 0xdeadbeef,
+			Body: errorCloser{nopCloser{strings.NewReader("\xde\xad\xbe\xef")}}}, nil
 	} else {
-		return nopCloser{bytes.NewReader(b)}, int64(len(b)), nil
+		return &http.Response{StatusCode: http.StatusOK, ContentLength: int64(len(b)),
+			Body: nopCloser{bytes.NewReader(b)}}, nil
 	}
 }
 

song.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"net/http"
 	"os"
 	"slices"
 )
@@ -79,13 +80,16 @@ func (s *Song) Enrich(ctx context.Context, n Net) error {
 	}
 
 	var v SongResponse
-	if body, _, err := n.Get(ctx, APIPrefix+"/song/"+s.CID.String()); err != nil {
+	u := APIPrefix + "/song/" + s.CID.String()
+	if resp, err := n.Get(ctx, u); err != nil {
 		return err
+	} else if resp.StatusCode != http.StatusOK {
+		return &ResponseStatusError{u, resp.StatusCode, resp.Body.Close()}
 	} else {
-		if err = json.NewDecoder(body).Decode(&v); err != nil {
-			return errors.Join(body.Close(), err)
+		if err = json.NewDecoder(resp.Body).Decode(&v); err != nil {
+			return errors.Join(resp.Body.Close(), err)
 		}
-		if err = body.Close(); err != nil {
+		if err = resp.Body.Close(); err != nil {
 			return err
 		}
 	}

song_test.go

@@ -113,6 +113,19 @@ func TestSongEnrich(t *testing.T) {
 			makeSongPath(48794): []byte{0},
 		}, Song{}, errors.Join(newSyntaxError("invalid character '\\x00' looking for beginning of value", 1))},
 
+		{"status", Song{
+			CID:      48794,
+			Name:     "Warm and Small Light",
+			AlbumCID: 6660,
+			Artists:  []string{"塞壬唱片-MSR"},
+		}, stubNet{
+			makeSongPath(48794): []byte{0xde, 0xad, 0xbe, 0xef},
+		}, Song{}, &ResponseStatusError{
+			URL:        "https://monster-siren.hypergryph.com/api/song/048794",
+			StatusCode: 0xdeadbeef,
+			CloseErr:   os.ErrInvalid,
+		}},
+
 		{"close", Song{
 			CID:      48794,
 			Name:     "Warm and Small Light",