package encode

import (
	"math"
	"os"
	"os/exec"
	"strings"
	"testing"

	"github.com/netsynth/netsynth/classify"
	"github.com/netsynth/netsynth/synth"
)

// TestMP3Valid synthesizes from 3 synthetic WindowSnapshots and validates the
// output file is a valid MP3 using ffprobe.
func TestMP3Valid(t *testing.T) {
	// Check ffprobe is available
	if _, err := exec.LookPath("ffprobe"); err != nil {
		t.Skip("ffprobe not found in PATH; skipping MP3 validation test")
	}

	snaps := []classify.WindowSnapshot{
		{
			Counts: map[classify.TrafficClass]int64{
				classify.ClassICMP: 50,
				classify.ClassDNS:  30,
			},
			TotalPackets: 80,
			WindowIndex:  0,
		},
		{
			Counts: map[classify.TrafficClass]int64{
				classify.ClassHTTPS: 200,
			},
			TotalPackets: 200,
			WindowIndex:  1,
		},
		{
			Counts: map[classify.TrafficClass]int64{
				classify.ClassSSH:  10,
				classify.ClassHTTP: 80,
			},
			TotalPackets: 90,
			WindowIndex:  2,
		},
	}

	tmpFile, err := os.CreateTemp("", "netsynth-test-*.mp3")
	if err != nil {
		t.Fatalf("create temp file: %v", err)
	}
	tmpPath := tmpFile.Name()
	tmpFile.Close()
	defer os.Remove(tmpPath)

	if err := RunSynthesis(snaps, tmpPath, synth.ClassFreqConfigs); err != nil {
		t.Fatalf("RunSynthesis: %v", err)
	}

	// Verify file exists and is non-empty
	info, err := os.Stat(tmpPath)
	if err != nil {
		t.Fatalf("stat output file: %v", err)
	}
	if info.Size() == 0 {
		t.Fatal("output file is empty")
	}

	// Validate with ffprobe
	out, err := exec.Command("ffprobe",
		"-v", "error",
		"-show_entries", "format=format_name,duration,nb_streams",
		"-of", "csv=p=0",
		tmpPath,
	).CombinedOutput()
	if err != nil {
		t.Fatalf("ffprobe error: %v\noutput: %s", err, out)
	}

	outStr := string(out)
	if !strings.Contains(outStr, "mp3") {
		t.Errorf("expected format_name to contain 'mp3', got: %q", outStr)
	}

	// ffprobe csv=p=0 format: format_name,duration,nb_streams
	// Duration should be > 0; nb_streams should be 1
	// We check that the output is non-empty and contains expected fields
	fields := strings.Split(strings.TrimSpace(outStr), ",")
	if len(fields) < 3 {
		t.Errorf("unexpected ffprobe output format: %q", outStr)
	}
}

// TestZeroPacketError verifies that RunSynthesis returns an error containing
// "no packets" and does NOT create an output file when given zero-packet input.
func TestZeroPacketError(t *testing.T) {
	// Test 1: empty snapshot slice
	tmpPath := "/tmp/netsynth-should-not-exist-" + t.Name() + ".mp3"
	defer os.Remove(tmpPath)

	err := RunSynthesis([]classify.WindowSnapshot{}, tmpPath, synth.ClassFreqConfigs)
	if err == nil {
		t.Fatal("expected error for empty snapshot slice, got nil")
	}
	if !strings.Contains(err.Error(), "no packets") {
		t.Errorf("expected error to contain 'no packets', got: %q", err.Error())
	}
	if _, statErr := os.Stat(tmpPath); !os.IsNotExist(statErr) {
		t.Error("output file should NOT exist after zero-packet error")
		os.Remove(tmpPath)
	}

	// Test 2: snapshots where all TotalPackets == 0
	tmpPath2 := "/tmp/netsynth-should-not-exist-zero-" + t.Name() + ".mp3"
	defer os.Remove(tmpPath2)

	zeroSnaps := []classify.WindowSnapshot{
		{Counts: map[classify.TrafficClass]int64{}, TotalPackets: 0, WindowIndex: 0},
		{Counts: map[classify.TrafficClass]int64{}, TotalPackets: 0, WindowIndex: 1},
	}
	err2 := RunSynthesis(zeroSnaps, tmpPath2, synth.ClassFreqConfigs)
	if err2 == nil {
		t.Fatal("expected error for zero-packet snapshots, got nil")
	}
	if !strings.Contains(err2.Error(), "no packets") {
		t.Errorf("expected error to contain 'no packets', got: %q", err2.Error())
	}
	if _, statErr := os.Stat(tmpPath2); !os.IsNotExist(statErr) {
		t.Error("output file should NOT exist after zero-packet error")
		os.Remove(tmpPath2)
	}
}

// TestEncodeMP3DirectBytes encodes a 440 Hz sine wave directly via EncodeMP3
// and validates the output as a valid MP3 file.
func TestEncodeMP3DirectBytes(t *testing.T) {
	if _, err := exec.LookPath("ffprobe"); err != nil {
		t.Skip("ffprobe not found in PATH; skipping MP3 validation test")
	}

	// Generate 1 second of 440 Hz stereo sine wave
	sampleRate := synth.SampleRate
	numFrames := sampleRate
	frames := make([][2]float64, numFrames)
	for i := range frames {
		v := 0.5 * math.Sin(2.0*math.Pi*440.0*float64(i)/float64(sampleRate))
		frames[i] = [2]float64{v, v}
	}

	tmpFile, err := os.CreateTemp("", "netsynth-sine-test-*.mp3")
	if err != nil {
		t.Fatalf("create temp file: %v", err)
	}
	tmpPath := tmpFile.Name()
	tmpFile.Close()
	defer os.Remove(tmpPath)

	if err := EncodeMP3(tmpPath, frames, sampleRate); err != nil {
		t.Fatalf("EncodeMP3: %v", err)
	}

	info, err := os.Stat(tmpPath)
	if err != nil {
		t.Fatalf("stat output file: %v", err)
	}
	if info.Size() == 0 {
		t.Fatal("output file is empty")
	}

	out, err := exec.Command("ffprobe",
		"-v", "error",
		"-show_entries", "format=format_name",
		"-of", "csv=p=0",
		tmpPath,
	).CombinedOutput()
	if err != nil {
		t.Fatalf("ffprobe error: %v\noutput: %s", err, out)
	}
	if !strings.Contains(string(out), "mp3") {
		t.Errorf("expected MP3 format, got: %q", string(out))
	}
}