package services

import (
	"context"
	"encoding/json"
	"fmt"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"time"

	"github.com/google/uuid"
	"go.uber.org/zap"
	"gorm.io/gorm"

	"veza-backend-api/internal/models"
	"veza-backend-api/internal/utils"
)

type WaveformData struct {
	Version         int       `json:"version"`
	Channels        int       `json:"channels"`
	SampleRate      int       `json:"sample_rate"`
	SamplesPerPixel int       `json:"samples_per_pixel"`
	Bits            int       `json:"bits"`
	Length          int       `json:"length"`
	Data            []float64 `json:"data"`
}

type WaveformService struct {
	db           *gorm.DB
	logger       *zap.Logger
	s3Service    *S3StorageService
	cacheService *CacheService
	tempDir      string
}

func NewWaveformService(db *gorm.DB, logger *zap.Logger, s3Service *S3StorageService) *WaveformService {
	tempDir := os.TempDir()
	return &WaveformService{
		db:        db,
		logger:    logger,
		s3Service: s3Service,
		tempDir:   tempDir,
	}
}

func (s *WaveformService) SetCacheService(cache *CacheService) {
	s.cacheService = cache
}

func (s *WaveformService) GenerateWaveformAsync(ctx context.Context, trackID uuid.UUID, inputPath string) {
	go func() {
		genCtx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
		defer cancel()

		if err := s.generateWaveform(genCtx, trackID, inputPath); err != nil {
			s.logger.Error("Waveform generation failed",
				zap.String("track_id", trackID.String()),
				zap.Error(err),
			)
		}
	}()
}

func (s *WaveformService) generateWaveform(ctx context.Context, trackID uuid.UUID, inputPath string) error {
	if !utils.ValidateExecPath(inputPath) {
		return fmt.Errorf("invalid input path")
	}
	wavPath := filepath.Join(s.tempDir, fmt.Sprintf("waveform_%s.wav", trackID))
	jsonPath := filepath.Join(s.tempDir, fmt.Sprintf("waveform_%s.json", trackID))
	defer os.Remove(wavPath)
	defer os.Remove(jsonPath)

	ffmpegCmd := exec.CommandContext(ctx, "ffmpeg",
		"-y", "-i", inputPath,
		"-ac", "1",
		"-filter:a", "aresample=8000",
		"-f", "wav", wavPath,
	)
	if out, err := ffmpegCmd.CombinedOutput(); err != nil {
		return fmt.Errorf("ffmpeg WAV conversion failed: %w (output: %s)", err, string(out))
	}

	awCmd := exec.CommandContext(ctx, "audiowaveform",
		"--input-format", "wav",
		"--output-format", "json",
		"--pixels-per-second", "10",
		"-i", wavPath,
		"-o", jsonPath,
	)
	if _, err := awCmd.CombinedOutput(); err != nil {
		return s.generateFallbackWaveform(ctx, trackID, inputPath)
	}

	jsonData, err := os.ReadFile(jsonPath)
	if err != nil {
		return fmt.Errorf("failed to read waveform JSON: %w", err)
	}

	s3Key := fmt.Sprintf("waveforms/%s.json", trackID)
	if s.s3Service != nil {
		if _, err := s.s3Service.UploadFile(ctx, jsonData, s3Key, "application/json"); err != nil {
			return fmt.Errorf("failed to upload waveform to S3: %w", err)
		}
	}

	result := s.db.WithContext(ctx).Model(&models.Track{}).
		Where("id = ?", trackID).
		Update("waveform_url", s3Key)
	if result.Error != nil {
		return fmt.Errorf("failed to update track waveform_url: %w", result.Error)
	}

	s.logger.Info("Waveform generated successfully",
		zap.String("track_id", trackID.String()),
		zap.String("s3_key", s3Key),
	)
	return nil
}

func (s *WaveformService) generateFallbackWaveform(ctx context.Context, trackID uuid.UUID, inputPath string) error {
	if !utils.ValidateExecPath(inputPath) {
		return fmt.Errorf("invalid input path")
	}
	s.logger.Warn("audiowaveform not available, generating fallback waveform via FFmpeg",
		zap.String("track_id", trackID.String()),
	)

	pcmPath := filepath.Join(s.tempDir, fmt.Sprintf("raw_%s.pcm", trackID))
	defer os.Remove(pcmPath)

	cmd := exec.CommandContext(ctx, "ffmpeg",
		"-y", "-i", inputPath,
		"-ac", "1",
		"-filter:a", "aresample=800",
		"-f", "f32le",
		"-acodec", "pcm_f32le",
		pcmPath,
	)
	if out, err := cmd.CombinedOutput(); err != nil {
		return fmt.Errorf("ffmpeg PCM extraction failed: %w (output: %s)", err, string(out))
	}

	pcmData, err := os.ReadFile(pcmPath)
	if err != nil {
		return fmt.Errorf("failed to read PCM data: %w", err)
	}

	samples := make([]float64, 0, len(pcmData)/4)
	for i := 0; i+3 < len(pcmData); i += 4 {
		bits := uint32(pcmData[i]) | uint32(pcmData[i+1])<<8 | uint32(pcmData[i+2])<<16 | uint32(pcmData[i+3])<<24
		val := float64(math.Float32frombits(bits))
		if val > 1.0 {
			val = 1.0
		} else if val < -1.0 {
			val = -1.0
		}
		samples = append(samples, val)
	}

	waveform := WaveformData{
		Version:         2,
		Channels:        1,
		SampleRate:      800,
		SamplesPerPixel: 1,
		Bits:            32,
		Length:          len(samples),
		Data:            samples,
	}

	jsonData, err := json.Marshal(waveform)
	if err != nil {
		return fmt.Errorf("failed to marshal waveform: %w", err)
	}

	s3Key := fmt.Sprintf("waveforms/%s.json", trackID)
	if s.s3Service != nil {
		if _, err := s.s3Service.UploadFile(ctx, jsonData, s3Key, "application/json"); err != nil {
			return fmt.Errorf("failed to upload fallback waveform to S3: %w", err)
		}
	}

	result := s.db.WithContext(ctx).Model(&models.Track{}).
		Where("id = ?", trackID).
		Update("waveform_url", s3Key)
	if result.Error != nil {
		return fmt.Errorf("failed to update track waveform_url: %w", result.Error)
	}

	s.logger.Info("Fallback waveform generated",
		zap.String("track_id", trackID.String()),
	)
	return nil
}

func (s *WaveformService) GetWaveform(ctx context.Context, trackID uuid.UUID) ([]byte, error) {
	cacheKey := fmt.Sprintf("waveform:%s", trackID)
	if s.cacheService != nil {
		var cached []byte
		if err := s.cacheService.Get(ctx, cacheKey, &cached); err == nil {
			return cached, nil
		}
	}

	var track models.Track
	if err := s.db.WithContext(ctx).Select("waveform_url").Where("id = ?", trackID).First(&track).Error; err != nil {
		return nil, fmt.Errorf("track not found: %w", err)
	}

	if track.WaveformURL == nil || *track.WaveformURL == "" {
		return nil, fmt.Errorf("waveform not yet generated")
	}

	if s.s3Service == nil {
		return nil, fmt.Errorf("S3 service not configured")
	}

	data, err := s.s3Service.DownloadFile(ctx, *track.WaveformURL)
	if err != nil {
		return nil, fmt.Errorf("failed to download waveform from S3: %w", err)
	}

	if s.cacheService != nil {
		_ = s.cacheService.Set(ctx, cacheKey, data, 1*time.Hour)
	}

	return data, nil
}