package cmd

import (
	"encoding/json"
	"flag"
	"fmt"
	"os"

	"skraak/wav"
)

// RunMetadata handles the "metadata" subcommand
//
// JSON output schema:
//
//	{
//	  "file": string,              // Path to the WAV file
//	  "duration_seconds": float,    // Duration in seconds
//	  "sample_rate": int,           // Sample rate in Hz
//	  "channels": int,              // Number of audio channels
//	  "bits_per_sample": int,       // Bits per sample
//	  "comment": string,            // WAV comment (omitted if empty)
//	  "artist": string,             // WAV artist (omitted if empty)
//	  "file_mod_time": string       // File modification time RFC3339 (omitted if zero)
//	}
func RunMetadata(args []string) error {
	fs := flag.NewFlagSet("metadata", flag.ExitOnError)
	filePath := fs.String("file", "", "Path to WAV file (required)")

	fs.Usage = usagePrinter(fs,
		"skraak metadata --file <path>",
		"Extract metadata from a WAV file header.",
		"skraak metadata --file recording.wav",
		"skraak metadata --file /path/to/audio.wav | jq '.duration_seconds'",
	)

	if err := fs.Parse(args); err != nil {
		return fmt.Errorf("parsing flags: %w", err)
	}

	if err := requireFlags(fs, map[string]any{"--file": *filePath}); err != nil {
		return err
	}

	metadata, err := wav.ParseWAVHeader(*filePath)
	if err != nil {
		return fmt.Errorf("parsing WAV header: %w", err)
	}

	output := map[string]any{
		"file":             *filePath,
		"duration_seconds": metadata.Duration,
		"sample_rate":      metadata.SampleRate,
		"channels":         metadata.Channels,
		"bits_per_sample":  metadata.BitsPerSample,
	}

	if metadata.Comment != "" {
		output["comment"] = metadata.Comment
	}
	if metadata.Artist != "" {
		output["artist"] = metadata.Artist
	}
	if !metadata.FileModTime.IsZero() {
		output["file_mod_time"] = metadata.FileModTime.Format("2006-01-02T15:04:05Z07:00")
	}

	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	if err := enc.Encode(output); err != nil {
		return fmt.Errorf("encoding output: %w", err)
	}
	return nil
}