first commit

2026-04-09 01:42:37 +02:00
commit 75ae131e2a
7 changed files with 1055 additions and 0 deletions
--- a/lyrics_api.go
+++ b/lyrics_api.go
@@ -0,0 +1,141 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+// LyricsResponse represents the API response structure.
+type LyricsResponse struct {
+	SyncedLyrics string `json:"syncedLyrics"`
+	PlainLyrics  string `json:"plainLyrics"`
+	Code         int    `json:"code"`
+}
+
+var (
+	errLyricsNotFound  = errors.New("lyrics not found")
+	errLyricsTemporary = errors.New("temporary lyrics fetch failure")
+	lyricsHTTPClient   = &http.Client{Timeout: 15 * time.Second}
+)
+
+type temporaryLyricsError struct {
+	Reason     string
+	RetryAfter time.Duration
+}
+
+func (e *temporaryLyricsError) Error() string {
+	if e.RetryAfter > 0 {
+		return fmt.Sprintf("%s: retry after %s", e.Reason, e.RetryAfter)
+	}
+
+	return e.Reason
+}
+
+func (e *temporaryLyricsError) Unwrap() error {
+	return errLyricsTemporary
+}
+
+func fetchLyrics(metadata Metadata) (LyricsResponse, error) {
+	for attempt := 1; attempt <= 3; attempt++ {
+		lyrics, err := fetchLyricsOnce(metadata)
+		if err == nil {
+			return lyrics, nil
+		}
+
+		if !errors.Is(err, errLyricsTemporary) || attempt == 3 {
+			return LyricsResponse{}, err
+		}
+
+		retryDelay := time.Duration(attempt) * time.Second
+		var temporaryErr *temporaryLyricsError
+		if errors.As(err, &temporaryErr) && temporaryErr.RetryAfter > 0 {
+			retryDelay = temporaryErr.RetryAfter
+		}
+
+		time.Sleep(retryDelay)
+	}
+
+	return LyricsResponse{}, fmt.Errorf("lyrics fetch retries exhausted")
+}
+
+func fetchLyricsOnce(metadata Metadata) (LyricsResponse, error) {
+	apiURL := fmt.Sprintf("https://lrclib.net/api/get?track_name=%s&artist_name=%s&album_name=%s&duration=%d",
+		url.QueryEscape(metadata.TrackName),
+		url.QueryEscape(metadata.ArtistName),
+		url.QueryEscape(metadata.AlbumName),
+		metadata.Duration)
+
+	resp, err := lyricsHTTPClient.Get(apiURL)
+	if err != nil {
+		return LyricsResponse{}, &temporaryLyricsError{Reason: fmt.Sprintf("request failed: %v", err)}
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotFound {
+		return LyricsResponse{}, errLyricsNotFound
+	}
+
+	if resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode >= http.StatusInternalServerError {
+		retryAfter := parseRetryAfter(resp.Header.Get("Retry-After"))
+		return LyricsResponse{}, &temporaryLyricsError{Reason: fmt.Sprintf("http status %d", resp.StatusCode), RetryAfter: retryAfter}
+	}
+
+	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+		return LyricsResponse{}, fmt.Errorf("lyrics API returned status %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return LyricsResponse{}, err
+	}
+
+	var lyricsResp LyricsResponse
+	err = json.Unmarshal(body, &lyricsResp)
+	if err != nil {
+		return LyricsResponse{}, err
+	}
+
+	if lyricsResp.Code == 404 {
+		return LyricsResponse{}, errLyricsNotFound
+	}
+
+	if lyricsResp.Code >= 500 {
+		return LyricsResponse{}, &temporaryLyricsError{Reason: fmt.Sprintf("api code %d", lyricsResp.Code)}
+	}
+
+	return lyricsResp, nil
+}
+
+func parseRetryAfter(value string) time.Duration {
+	if value == "" {
+		return 0
+	}
+
+	seconds, err := strconv.Atoi(value)
+	if err == nil {
+		if seconds < 0 {
+			return 0
+		}
+		return time.Duration(seconds) * time.Second
+	}
+
+	retryTime, err := time.Parse(time.RFC1123, value)
+	if err != nil {
+		retryTime, err = time.Parse(time.RFC1123Z, value)
+		if err != nil {
+			return 0
+		}
+	}
+
+	if retryTime.Before(time.Now()) {
+		return 0
+	}
+
+	return time.Until(retryTime)
+}