refactor

internal/sync/sync.go

@@ -0,0 +1,79 @@
+package sync
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"sub-cli/internal/format/lrc"
+	"sub-cli/internal/model"
+)
+
+// SyncLyrics synchronizes the timeline of a source lyrics file with a target lyrics file
+func SyncLyrics(sourceFile, targetFile string) error {
+	sourceFmt := strings.TrimPrefix(filepath.Ext(sourceFile), ".")
+	targetFmt := strings.TrimPrefix(filepath.Ext(targetFile), ".")
+	
+	// Currently only supports LRC files
+	if sourceFmt != "lrc" || targetFmt != "lrc" {
+		return fmt.Errorf("sync only supports LRC files currently")
+	}
+	
+	source, err := lrc.Parse(sourceFile)
+	if err != nil {
+		return fmt.Errorf("error parsing source file: %w", err)
+	}
+	
+	target, err := lrc.Parse(targetFile)
+	if err != nil {
+		return fmt.Errorf("error parsing target file: %w", err)
+	}
+	
+	// Apply timeline from source to target
+	syncedLyrics := syncTimeline(source, target)
+	
+	// Write the synced lyrics to the target file
+	return lrc.Generate(syncedLyrics, targetFile)
+}
+
+// syncTimeline applies the timeline from the source lyrics to the target lyrics
+func syncTimeline(source, target model.Lyrics) model.Lyrics {
+	result := model.Lyrics{
+		Metadata: target.Metadata,
+		Content:  target.Content,
+	}
+	
+	// Use source timeline if available and lengths match
+	if len(source.Timeline) > 0 && len(source.Timeline) == len(target.Content) {
+		result.Timeline = source.Timeline
+	} else if len(source.Timeline) > 0 {
+		// If lengths don't match, scale timeline
+		result.Timeline = scaleTimeline(source.Timeline, len(target.Content))
+	}
+	
+	return result
+}
+
+// scaleTimeline scales a timeline to match a different number of entries
+func scaleTimeline(timeline []model.Timestamp, targetCount int) []model.Timestamp {
+	if targetCount <= 0 || len(timeline) == 0 {
+		return []model.Timestamp{}
+	}
+	
+	result := make([]model.Timestamp, targetCount)
+	
+	if targetCount == 1 {
+		result[0] = timeline[0]
+		return result
+	}
+	
+	sourceLength := len(timeline)
+	
+	for i := 0; i < targetCount; i++ {
+		// Scale index to match source timeline
+		sourceIndex := i * (sourceLength - 1) / (targetCount - 1)
+		result[i] = timeline[sourceIndex]
+	}
+	
+	return result
+}