package backend

import (
	"encoding/json"
	"time"

	"music-server/internal/logging"

	"go.uber.org/zap"
)

// GameWithSongs represents a game with its songs for statistics
type GameWithSongs struct {
	SoundtrackID        int32     `json:"game_id"`
	SoundtrackName      string    `json:"game_name"`
	SoundtrackPlayed    int32     `json:"game_played"`
	SoundtrackLastPlayed *time.Time `json:"game_last_played,omitempty"`
	Songs        []SongInfoForStats `json:"songs"`
}

// SongInfoForStats represents a song with game info for statistics
type SongInfoForStats struct {
	SoundtrackID      int32     `json:"game_id"`
	SoundtrackName    string    `json:"game_name"`
	SongName    string    `json:"song_name"`
	Path        string    `json:"path"`
	TimesPlayed int32     `json:"times_played"`
	FileName    *string   `json:"file_name,omitempty"`
}

// StatisticsSummary holds overall statistics
type StatisticsSummary struct {
	TotalGames        int64   `json:"total_games"`
	PlayedGames       int64   `json:"played_games"`
	NeverPlayedGames  int64   `json:"never_played_games"`
	TotalGamePlays    int64   `json:"total_game_plays"`
	AvgGamePlays      float64 `json:"avg_game_plays"`
	MaxGamePlays      int64   `json:"max_game_plays"`
	MinGamePlays      int64   `json:"min_game_plays"`
}

// StatisticsHandler manages statistics operations
type StatisticsHandler struct {
	// Uses the global backend repo initialized via InitBackend
}

// NewStatisticsHandler creates a new StatisticsHandler
func NewStatisticsHandler() *StatisticsHandler {
	return &StatisticsHandler{}
}

// GetMostPlayedGamesWithSongs returns the top N most played games with their songs
func (h *StatisticsHandler) GetMostPlayedGamesWithSongs(limit int32) ([]GameWithSongs, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	// Get raw results
	rows, err := queries.GetMostPlayedGamesWithSongs(ctx, limit)
	if err != nil {
		return nil, err
	}
	
	// Convert to GameWithSongs
	var result []GameWithSongs
	for _, row := range rows {
		var songs []SongInfoForStats
		if row.Songs != nil {
			// Parse JSON songs array
			if err := json.Unmarshal(row.Songs, &songs); err != nil {
				// Fallback: if JSON parsing fails, create empty song entries
				songs = make([]SongInfoForStats, 0)
			}
		}
		result = append(result, GameWithSongs{
			SoundtrackID:        row.SoundtrackID,
			SoundtrackName:      row.SoundtrackName,
			SoundtrackPlayed:    row.SoundtrackPlayed,
			SoundtrackLastPlayed: row.SoundtrackLastPlayed,
			Songs:         songs,
		})
	}
	return result, nil
}

// GetLeastPlayedGamesWithSongs returns the top N least played games with their songs
func (h *StatisticsHandler) GetLeastPlayedGamesWithSongs(limit int32) ([]GameWithSongs, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	rows, err := queries.GetLeastPlayedGamesWithSongs(ctx, limit)
	if err != nil {
		return nil, err
	}
	
	var result []GameWithSongs
	for _, row := range rows {
		var songs []SongInfoForStats
		if row.Songs != nil {
			if err := json.Unmarshal(row.Songs, &songs); err != nil {
				songs = make([]SongInfoForStats, 0)
			}
		}
		result = append(result, GameWithSongs{
			SoundtrackID:        row.SoundtrackID,
			SoundtrackName:      row.SoundtrackName,
			SoundtrackPlayed:    row.SoundtrackPlayed,
			SoundtrackLastPlayed: row.SoundtrackLastPlayed,
			Songs:         songs,
		})
	}
	return result, nil
}

// GetMostPlayedSongsWithGame returns the top N most played songs with their game info
func (h *StatisticsHandler) GetMostPlayedSongsWithGame(limit int32) ([]SongInfoForStats, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	rows, err := queries.GetMostPlayedSongsWithGame(ctx, limit)
	if err != nil {
		return nil, err
	}
	
	var result []SongInfoForStats
	for _, row := range rows {
		result = append(result, SongInfoForStats{
			SoundtrackID:      row.SoundtrackID,
			SoundtrackName:    row.SoundtrackName,
			SongName:    row.SongName,
			Path:        row.Path,
			TimesPlayed: row.TimesPlayed,
			FileName:    row.FileName,
		})
	}
	return result, nil
}

// GetLeastPlayedSongsWithGame returns the top N least played songs with their game info
func (h *StatisticsHandler) GetLeastPlayedSongsWithGame(limit int32) ([]SongInfoForStats, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	rows, err := queries.GetLeastPlayedSongsWithGame(ctx, limit)
	if err != nil {
		return nil, err
	}
	
	var result []SongInfoForStats
	for _, row := range rows {
		result = append(result, SongInfoForStats{
			SoundtrackID:      row.SoundtrackID,
			SoundtrackName:    row.SoundtrackName,
			SongName:    row.SongName,
			Path:        row.Path,
			TimesPlayed: row.TimesPlayed,
			FileName:    row.FileName,
		})
	}
	return result, nil
}

// GetNeverPlayedGames returns games that have never been played
func (h *StatisticsHandler) GetNeverPlayedGames() ([]GameWithSongs, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	rows, err := queries.GetNeverPlayedGames(ctx)
	if err != nil {
		return nil, err
	}
	
	var result []GameWithSongs
	for _, row := range rows {
		var songs []SongInfoForStats
		if row.Songs != nil {
			if err := json.Unmarshal(row.Songs, &songs); err != nil {
				songs = make([]SongInfoForStats, 0)
			}
		}
		result = append(result, GameWithSongs{
			SoundtrackID:        row.SoundtrackID,
			SoundtrackName:      row.SoundtrackName,
			SoundtrackPlayed:    row.SoundtrackPlayed,
			SoundtrackLastPlayed: nil,
			Songs:         songs,
		})
	}
	return result, nil
}

// GetLastPlayedGames returns the most recently played games
func (h *StatisticsHandler) GetLastPlayedGames(limit int32) ([]GameWithSongs, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	rows, err := queries.GetLastPlayedGames(ctx, limit)
	if err != nil {
		return nil, err
	}
	
	var result []GameWithSongs
	for _, row := range rows {
		var songs []SongInfoForStats
		if row.Songs != nil {
			if err := json.Unmarshal(row.Songs, &songs); err != nil {
				songs = make([]SongInfoForStats, 0)
			}
		}
		result = append(result, GameWithSongs{
			SoundtrackID:        row.SoundtrackID,
			SoundtrackName:      row.SoundtrackName,
			SoundtrackPlayed:    row.SoundtrackPlayed,
			SoundtrackLastPlayed: row.SoundtrackLastPlayed,
			Songs:         songs,
		})
	}
	return result, nil
}

// GetOldestPlayedGames returns the least recently played games
func (h *StatisticsHandler) GetOldestPlayedGames(limit int32) ([]GameWithSongs, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	rows, err := queries.GetOldestPlayedGames(ctx, limit)
	if err != nil {
		return nil, err
	}
	
	var result []GameWithSongs
	for _, row := range rows {
		var songs []SongInfoForStats
		if row.Songs != nil {
			if err := json.Unmarshal(row.Songs, &songs); err != nil {
				songs = make([]SongInfoForStats, 0)
			}
		}
		result = append(result, GameWithSongs{
			SoundtrackID:        row.SoundtrackID,
			SoundtrackName:      row.SoundtrackName,
			SoundtrackPlayed:    row.SoundtrackPlayed,
			SoundtrackLastPlayed: row.SoundtrackLastPlayed,
			Songs:         songs,
		})
	}
	return result, nil
}

// GetStatisticsSummary returns overall statistics
func (h *StatisticsHandler) GetStatisticsSummary() (*StatisticsSummary, error) {
	queries := BackendRepo()
	ctx := BackendCtx()
	
	row, err := queries.GetStatisticsSummary(ctx)
	if err != nil {
		return nil, err
	}
	
	return &StatisticsSummary{
		TotalGames:       int64(row.TotalSoundtracks),
		PlayedGames:      int64(row.PlayedSoundtracks),
		NeverPlayedGames: int64(row.NeverPlayedSoundtracks),
		TotalGamePlays:   int64(row.TotalSoundtrackPlays),
		AvgGamePlays:     float64(row.AvgSoundtrackPlays),
		MaxGamePlays:     int64(row.MaxSoundtrackPlays),
		MinGamePlays:     int64(row.MinSoundtrackPlays),
	}, nil
}

// Log helper for statistics operations
func logStatisticsError(err error, operation string) {
	if err != nil {
		logging.GetLogger().Error("Statistics error",
			zap.String("operation", operation),
			zap.String("error", err.Error()))
	}
}