feat: srt sync and formatting

internal/config/constants.go

@@ -6,13 +6,18 @@ const Version = "0.4.0"
 // Usage stores the general usage information
 const Usage = `Usage: sub-cli [command] [options]
   Commands:
-    sync	Synchronize timeline of two lyrics files
-    convert	Convert lyrics file to another format
-    fmt		Format lyrics file
+    sync	Synchronize timeline of two subtitle files
+    convert	Convert subtitle file to another format
+    fmt		Format subtitle file
     help	Show help`
 
 // SyncUsage stores the usage information for the sync command
-const SyncUsage = `Usage: sub-cli sync <source> <target>`
+const SyncUsage = `Usage: sub-cli sync <source> <target>
+  Note: 
+  Currently supports synchronizing between files of the same format:
+  - LRC to LRC
+  - SRT to SRT
+  If source and target have different numbers of entries, a warning will be shown.`
 
 // ConvertUsage stores the usage information for the convert command
 const ConvertUsage = `Usage: sub-cli convert <source> <target>

internal/format/srt/srt.go

@@ -122,6 +122,23 @@ func formatSRTTimestamp(ts model.Timestamp) string {
 		ts.Milliseconds)
 }
 
+// Format standardizes and formats an SRT file
+func Format(filePath string) error {
+	// Parse the file
+	entries, err := Parse(filePath)
+	if err != nil {
+		return fmt.Errorf("error parsing SRT file: %w", err)
+	}
+
+	// Standardize entry numbering and ensure consistent formatting
+	for i := range entries {
+		entries[i].Number = i + 1 // Ensure sequential numbering
+	}
+
+	// Write back the formatted content
+	return Generate(entries, filePath)
+}
+
 // ConvertToLyrics converts SRT entries to a Lyrics structure
 func ConvertToLyrics(entries []model.SRTEntry) model.Lyrics {
 	lyrics := model.Lyrics{

internal/formatter/formatter.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"sub-cli/internal/format/lrc"
+	"sub-cli/internal/format/srt"
 )
 
 // Format formats a subtitle file to ensure consistent formatting
@@ -15,6 +16,8 @@ func Format(filePath string) error {
 	switch ext {
 	case "lrc":
 		return lrc.Format(filePath)
+	case "srt":
+		return srt.Format(filePath)
 	default:
 		return fmt.Errorf("unsupported format for formatting: %s", ext)
 	}

internal/sync/sync.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"sub-cli/internal/format/lrc"
+	"sub-cli/internal/format/srt"
 	"sub-cli/internal/model"
 )
 
@@ -14,11 +15,18 @@ 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")
+	// Check for supported format combinations
+	if sourceFmt == "lrc" && targetFmt == "lrc" {
+		return syncLRCFiles(sourceFile, targetFile)
+	} else if sourceFmt == "srt" && targetFmt == "srt" {
+		return syncSRTFiles(sourceFile, targetFile)
+	} else {
+		return fmt.Errorf("sync only supports files of the same format (lrc-to-lrc or srt-to-srt)")
+	}
 }
 
+// syncLRCFiles synchronizes two LRC files
+func syncLRCFiles(sourceFile, targetFile string) error {
 	source, err := lrc.Parse(sourceFile)
 	if err != nil {
 		return fmt.Errorf("error parsing source file: %w", err)
@@ -29,15 +37,46 @@ func SyncLyrics(sourceFile, targetFile string) error {
 		return fmt.Errorf("error parsing target file: %w", err)
 	}
 	
+	// Check if line counts match
+	if len(source.Timeline) != len(target.Content) {
+		fmt.Printf("Warning: Source timeline (%d entries) and target content (%d entries) have different counts. Timeline will be scaled.\n", 
+			len(source.Timeline), len(target.Content))
+	}
+	
 	// Apply timeline from source to target
-	syncedLyrics := syncTimeline(source, target)
+	syncedLyrics := syncLRCTimeline(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 {
+// syncSRTFiles synchronizes two SRT files
+func syncSRTFiles(sourceFile, targetFile string) error {
+	sourceEntries, err := srt.Parse(sourceFile)
+	if err != nil {
+		return fmt.Errorf("error parsing source SRT file: %w", err)
+	}
+	
+	targetEntries, err := srt.Parse(targetFile)
+	if err != nil {
+		return fmt.Errorf("error parsing target SRT file: %w", err)
+	}
+	
+	// Check if entry counts match
+	if len(sourceEntries) != len(targetEntries) {
+		fmt.Printf("Warning: Source (%d entries) and target (%d entries) have different entry counts. Timeline will be adjusted.\n", 
+			len(sourceEntries), len(targetEntries))
+	}
+	
+	// Sync the timelines
+	syncedEntries := syncSRTTimeline(sourceEntries, targetEntries)
+	
+	// Write the synced entries to the target file
+	return srt.Generate(syncedEntries, targetFile)
+}
+
+// syncLRCTimeline applies the timeline from the source lyrics to the target lyrics
+func syncLRCTimeline(source, target model.Lyrics) model.Lyrics {
 	result := model.Lyrics{
 		Metadata: target.Metadata,
 		Content:  target.Content,
@@ -54,6 +93,64 @@ func syncTimeline(source, target model.Lyrics) model.Lyrics {
 	return result
 }
 
+// syncSRTTimeline applies the timing from source SRT entries to target SRT entries
+func syncSRTTimeline(sourceEntries, targetEntries []model.SRTEntry) []model.SRTEntry {
+	result := make([]model.SRTEntry, len(targetEntries))
+	
+	// Copy target entries
+	copy(result, targetEntries)
+	
+	// If source and target have the same number of entries, directly apply timings
+	if len(sourceEntries) == len(targetEntries) {
+		for i := range result {
+			result[i].StartTime = sourceEntries[i].StartTime
+			result[i].EndTime = sourceEntries[i].EndTime
+		}
+	} else {
+		// If entry counts differ, scale the timing
+		for i := range result {
+			// Calculate scaled index
+			sourceIdx := 0
+			if len(sourceEntries) > 1 {
+				sourceIdx = i * (len(sourceEntries) - 1) / (len(targetEntries) - 1)
+			}
+			
+			// Ensure the index is within bounds
+			if sourceIdx >= len(sourceEntries) {
+				sourceIdx = len(sourceEntries) - 1
+			}
+			
+			// Apply the scaled timing
+			result[i].StartTime = sourceEntries[sourceIdx].StartTime
+			
+			// Calculate end time: if not the last entry, use duration from source
+			if i < len(result)-1 {
+				// If next source entry exists, calculate duration
+				var duration model.Timestamp
+				if sourceIdx+1 < len(sourceEntries) {
+					duration = calculateDuration(sourceEntries[sourceIdx].StartTime, sourceEntries[sourceIdx+1].StartTime)
+				} else {
+					// If no next source entry, use the source's end time (usually a few seconds after start)
+					duration = calculateDuration(sourceEntries[sourceIdx].StartTime, sourceEntries[sourceIdx].EndTime)
+				}
+				
+				// Apply duration to next start time
+				result[i].EndTime = addDuration(result[i].StartTime, duration)
+			} else {
+				// For the last entry, add a fixed duration (e.g., 3 seconds)
+				result[i].EndTime = sourceEntries[sourceIdx].EndTime
+			}
+		}
+	}
+	
+	// Ensure proper sequence numbering
+	for i := range result {
+		result[i].Number = i + 1
+	}
+	
+	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 {
@@ -77,3 +174,50 @@ func scaleTimeline(timeline []model.Timestamp, targetCount int) []model.Timestam
 	
 	return result
 }
+
+// calculateDuration calculates the time difference between two timestamps
+func calculateDuration(start, end model.Timestamp) model.Timestamp {
+	startMillis := start.Hours*3600000 + start.Minutes*60000 + start.Seconds*1000 + start.Milliseconds
+	endMillis := end.Hours*3600000 + end.Minutes*60000 + end.Seconds*1000 + end.Milliseconds
+	
+	durationMillis := endMillis - startMillis
+	if durationMillis < 0 {
+		durationMillis = 3000 // Default 3 seconds if negative
+	}
+	
+	hours := durationMillis / 3600000
+	durationMillis %= 3600000
+	minutes := durationMillis / 60000
+	durationMillis %= 60000
+	seconds := durationMillis / 1000
+	milliseconds := durationMillis % 1000
+	
+	return model.Timestamp{
+		Hours:        hours,
+		Minutes:      minutes,
+		Seconds:      seconds,
+		Milliseconds: milliseconds,
+	}
+}
+
+// addDuration adds a duration to a timestamp
+func addDuration(start, duration model.Timestamp) model.Timestamp {
+	startMillis := start.Hours*3600000 + start.Minutes*60000 + start.Seconds*1000 + start.Milliseconds
+	durationMillis := duration.Hours*3600000 + duration.Minutes*60000 + duration.Seconds*1000 + duration.Milliseconds
+	
+	totalMillis := startMillis + durationMillis
+	
+	hours := totalMillis / 3600000
+	totalMillis %= 3600000
+	minutes := totalMillis / 60000
+	totalMillis %= 60000
+	seconds := totalMillis / 1000
+	milliseconds := totalMillis % 1000
+	
+	return model.Timestamp{
+		Hours:        hours,
+		Minutes:      minutes,
+		Seconds:      seconds,
+		Milliseconds: milliseconds,
+	}
+}