package memory

import (
	"context"
	"encoding/json"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"
)

// Service manages user memory and preferences
type Service interface {
	GetProfile(ctx context.Context, userID, tenantID string) (*UserProfile, error)
	SaveProfile(ctx context.Context, profile *UserProfile) error
	GetHistory(ctx context.Context, userID, tenantID string, limit int) ([]ConversationHistory, error)
	SaveHistory(ctx context.Context, history *ConversationHistory) error
}

// UserProfile represents user preferences and memory
type UserProfile struct {
	UserID      string
	TenantID    string
	Preferences map[string]interface{}
	Context     map[string]interface{}
	CreatedAt   string
	UpdatedAt   string
}

// ConversationHistory represents a conversation history entry
type ConversationHistory struct {
	ID        string
	UserID    string
	TenantID  string
	SessionID string
	Messages  []Message
	CreatedAt string
}

// Message represents a message in history
type Message struct {
	Role    string
	Content string
	Timestamp string
}

// MemoryService implements memory using PostgreSQL
type MemoryService struct {
	db *pgxpool.Pool
}

// NewMemoryService creates a new memory service
func NewMemoryService(db *pgxpool.Pool) *MemoryService {
	return &MemoryService{
		db: db,
	}
}

// GetProfile gets user profile
func (s *MemoryService) GetProfile(ctx context.Context, userID, tenantID string) (*UserProfile, error) {
	query := `
		SELECT user_id, tenant_id, preferences, context, created_at, updated_at
		FROM user_profiles
		WHERE user_id = $1 AND tenant_id = $2
	`

	var profile UserProfile
	var prefsJSON, contextJSON []byte

	err := s.db.QueryRow(ctx, query, userID, tenantID).Scan(
		&profile.UserID,
		&profile.TenantID,
		&prefsJSON,
		&contextJSON,
		&profile.CreatedAt,
		&profile.UpdatedAt,
	)
	if err != nil {
		// Return default profile if not found
		return &UserProfile{
			UserID:      userID,
			TenantID:    tenantID,
			Preferences: make(map[string]interface{}),
			Context:     make(map[string]interface{}),
		}, nil
	}

	if err := json.Unmarshal(prefsJSON, &profile.Preferences); err != nil {
		profile.Preferences = make(map[string]interface{})
	}
	if err := json.Unmarshal(contextJSON, &profile.Context); err != nil {
		profile.Context = make(map[string]interface{})
	}

	return &profile, nil
}

// SaveProfile saves user profile
func (s *MemoryService) SaveProfile(ctx context.Context, profile *UserProfile) error {
	prefsJSON, _ := json.Marshal(profile.Preferences)
	contextJSON, _ := json.Marshal(profile.Context)

	query := `
		INSERT INTO user_profiles (user_id, tenant_id, preferences, context, created_at, updated_at)
		VALUES ($1, $2, $3, $4, NOW(), NOW())
		ON CONFLICT (user_id, tenant_id) DO UPDATE SET
			preferences = $3,
			context = $4,
			updated_at = NOW()
	`

	_, err := s.db.Exec(ctx, query, profile.UserID, profile.TenantID, prefsJSON, contextJSON)
	return err
}

// GetHistory gets conversation history
func (s *MemoryService) GetHistory(ctx context.Context, userID, tenantID string, limit int) ([]ConversationHistory, error) {
	if limit <= 0 {
		limit = 10
	}

	query := `
		SELECT id, user_id, tenant_id, session_id, messages, created_at
		FROM conversation_history
		WHERE user_id = $1 AND tenant_id = $2
		ORDER BY created_at DESC
		LIMIT $3
	`

	rows, err := s.db.Query(ctx, query, userID, tenantID, limit)
	if err != nil {
		return nil, fmt.Errorf("failed to query: %w", err)
	}
	defer rows.Close()

	var histories []ConversationHistory
	for rows.Next() {
		var history ConversationHistory
		var messagesJSON []byte
		if err := rows.Scan(&history.ID, &history.UserID, &history.TenantID, &history.SessionID, &messagesJSON, &history.CreatedAt); err != nil {
			continue
		}
		if err := json.Unmarshal(messagesJSON, &history.Messages); err != nil {
			history.Messages = []Message{}
		}
		histories = append(histories, history)
	}

	return histories, nil
}

// SaveHistory saves conversation history
func (s *MemoryService) SaveHistory(ctx context.Context, history *ConversationHistory) error {
	messagesJSON, _ := json.Marshal(history.Messages)

	query := `
		INSERT INTO conversation_history (id, user_id, tenant_id, session_id, messages, created_at)
		VALUES ($1, $2, $3, $4, $5, NOW())
	`

	_, err := s.db.Exec(ctx, query, history.ID, history.UserID, history.TenantID, history.SessionID, messagesJSON)
	return err
}