package user

import (
	"context"
	"errors"
	"fmt"
	"log"
	"os"
	"time"

	"dance-lessons-coach/pkg/config"

	"github.com/rs/zerolog"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
)

// ZerologWriter implements logger.Writer interface using zerolog
type ZerologWriter struct {
	logger zerolog.Logger
}

func (zw *ZerologWriter) Printf(format string, v ...interface{}) {
	message := fmt.Sprintf(format, v...)

	// Determine appropriate log level based on message content
	if len(message) > 0 {
		// Check for error indicators
		if containsErrorIndicators(message) {
			zw.logger.Error().Str("gorm", message).Send()
			return
		}

		// Check for slow query indicators
		if containsSlowQueryIndicators(message) {
			zw.logger.Warn().Str("gorm", message).Send()
			return
		}

		// Default to debug level for regular SQL queries
		zw.logger.Debug().Str("gorm", message).Send()
	}
}

// containsErrorIndicators checks if the message contains error-related keywords
func containsErrorIndicators(message string) bool {
	errorKeywords := []string{"error", "Error", "failed", "Failed", "not found", "Not Found"}
	for _, keyword := range errorKeywords {
		if containsIgnoreCase(message, keyword) {
			return true
		}
	}
	return false
}

// containsSlowQueryIndicators checks if the message contains slow query indicators
func containsSlowQueryIndicators(message string) bool {
	slowKeywords := []string{"slow", "Slow", "timeout", "Timeout"}
	for _, keyword := range slowKeywords {
		if containsIgnoreCase(message, keyword) {
			return true
		}
	}
	return false
}

// containsIgnoreCase performs case-insensitive string containment check
func containsIgnoreCase(s, substr string) bool {
	return containsIgnoreCaseBytes([]byte(s), []byte(substr))
}

// containsIgnoreCaseBytes is a helper for case-insensitive byte slice containment
func containsIgnoreCaseBytes(s, substr []byte) bool {
	if len(substr) == 0 {
		return true
	}
	if len(s) < len(substr) {
		return false
	}
	for i := 0; i <= len(s)-len(substr); i++ {
		match := true
		for j := 0; j < len(substr); j++ {
			if toLower(s[i+j]) != toLower(substr[j]) {
				match = false
				break
			}
		}
		if match {
			return true
		}
	}
	return false
}

// toLower converts byte to lowercase
func toLower(b byte) byte {
	if b >= 'A' && b <= 'Z' {
		return b + 32
	}
	return b
}

// PostgresRepository implements UserRepository using PostgreSQL
type PostgresRepository struct {
	db         *gorm.DB
	config     *config.Config
	spanPrefix string
}

// NewPostgresRepository creates a new PostgreSQL repository
func NewPostgresRepository(cfg *config.Config) (*PostgresRepository, error) {
	repo := &PostgresRepository{
		config:     cfg,
		spanPrefix: "user.repo.",
	}

	if err := repo.initializeDatabase(); err != nil {
		return nil, fmt.Errorf("failed to initialize PostgreSQL database: %w", err)
	}

	return repo, nil
}

// NewPostgresRepositoryFromDSN creates a PostgresRepository connected via the given DSN
// and runs AutoMigrate against it. Used by BDD test infra to create a per-scenario
// repository pointing at an isolated schema (the DSN typically includes search_path=<schema>).
//
// Pass the same cfg used elsewhere (it is required by methods that read pool settings),
// but the DSN passed here OVERRIDES the host/port/dbname/etc that cfg would have built.
func NewPostgresRepositoryFromDSN(cfg *config.Config, dsn string) (*PostgresRepository, error) {
	repo := &PostgresRepository{
		config:     cfg,
		spanPrefix: "user.repo.",
	}

	gormLogger := logger.New(
		log.New(os.Stderr, "\n", log.LstdFlags),
		logger.Config{
			SlowThreshold:             time.Second,
			LogLevel:                  logger.Warn,
			IgnoreRecordNotFoundError: true,
			Colorful:                  false,
		},
	)

	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{Logger: gormLogger})
	if err != nil {
		return nil, fmt.Errorf("failed to connect to PostgreSQL with custom DSN: %w", err)
	}

	sqlDB, err := db.DB()
	if err != nil {
		return nil, fmt.Errorf("failed to get sql.DB from gorm: %w", err)
	}
	sqlDB.SetMaxOpenConns(cfg.GetDatabaseMaxOpenConns())
	sqlDB.SetMaxIdleConns(cfg.GetDatabaseMaxIdleConns())
	sqlDB.SetConnMaxLifetime(cfg.GetDatabaseConnMaxLifetime())

	if err := db.AutoMigrate(&User{}); err != nil {
		return nil, fmt.Errorf("failed to auto-migrate via custom DSN: %w", err)
	}

	repo.db = db
	return repo, nil
}

// BuildSchemaIsolatedDSN returns a Postgres DSN that targets the given schema via
// the search_path connection parameter. Use with NewPostgresRepositoryFromDSN to
// get a repository whose connection only sees the per-scenario schema.
func BuildSchemaIsolatedDSN(cfg *config.Config, schemaName string) string {
	return fmt.Sprintf(
		"host=%s port=%d user=%s password=%s dbname=%s sslmode=%s search_path=%s",
		cfg.GetDatabaseHost(),
		cfg.GetDatabasePort(),
		cfg.GetDatabaseUser(),
		cfg.GetDatabasePassword(),
		cfg.GetDatabaseName(),
		cfg.GetDatabaseSSLMode(),
		schemaName,
	)
}

// Exec runs a raw SQL statement against the repository's connection.
// Used by BDD test infra for schema lifecycle (CREATE SCHEMA / DROP SCHEMA).
// Avoid in production code paths -- prefer the typed Repository methods.
func (r *PostgresRepository) Exec(sql string) error {
	if r.db == nil {
		return fmt.Errorf("Exec called on PostgresRepository with nil db")
	}
	return r.db.Exec(sql).Error
}

// initializeDatabase sets up the PostgreSQL database connection and runs migrations
func (r *PostgresRepository) initializeDatabase() error {
	// Configure GORM logger based on config
	var gormLogger logger.Interface
	if r.config.GetLoggingJSON() {
		// Create zerolog logger that respects the configured output
		var logOutput = os.Stderr

		// If a log file is configured, use it
		if output := r.config.GetLogOutput(); output != "" {
			if file, err := os.OpenFile(output, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644); err == nil {
				logOutput = file
			}
		}

		// Create zerolog logger with component context
		globalLogger := zerolog.New(logOutput).With().Str("component", "gorm").Logger()
		zw := &ZerologWriter{logger: globalLogger}
		gormLogger = logger.New(
			zw,
			logger.Config{
				SlowThreshold:             time.Second,
				LogLevel:                  logger.Warn,
				IgnoreRecordNotFoundError: true,
				Colorful:                  false,
			},
		)
	} else {
		// Use console logger for non-JSON mode
		gormLogger = logger.New(
			log.New(os.Stderr, "\n", log.LstdFlags),
			logger.Config{
				SlowThreshold:             time.Second,
				LogLevel:                  logger.Warn,
				IgnoreRecordNotFoundError: true,
				Colorful:                  true,
			},
		)
	}

	// Build PostgreSQL DSN
	dsn := fmt.Sprintf(
		"host=%s port=%d user=%s password=%s dbname=%s sslmode=%s",
		r.config.GetDatabaseHost(),
		r.config.GetDatabasePort(),
		r.config.GetDatabaseUser(),
		r.config.GetDatabasePassword(),
		r.config.GetDatabaseName(),
		r.config.GetDatabaseSSLMode(),
	)

	var err error
	r.db, err = gorm.Open(postgres.Open(dsn), &gorm.Config{
		Logger: gormLogger,
	})
	if err != nil {
		return fmt.Errorf("failed to connect to PostgreSQL: %w", err)
	}

	// Configure connection pool
	sqlDB, err := r.db.DB()
	if err != nil {
		return fmt.Errorf("failed to get SQL DB: %w", err)
	}

	// Set connection pool settings
	sqlDB.SetMaxOpenConns(r.config.GetDatabaseMaxOpenConns())
	sqlDB.SetMaxIdleConns(r.config.GetDatabaseMaxIdleConns())
	sqlDB.SetConnMaxLifetime(r.config.GetDatabaseConnMaxLifetime())

	// Auto-migrate the User model
	if err := r.db.AutoMigrate(&User{}); err != nil {
		return fmt.Errorf("failed to auto-migrate: %w", err)
	}

	return nil
}

// CreateUser creates a new user in the database
func (r *PostgresRepository) CreateUser(ctx context.Context, user *User) error {
	// Create telemetry span
	ctx, span := r.createSpan(ctx, "create_user")
	if span != nil {
		defer span.End()
	}

	result := r.db.WithContext(ctx).Create(user)
	if result.Error != nil {
		if span != nil {
			span.RecordError(result.Error)
		}
		return fmt.Errorf("failed to create user: %w", result.Error)
	}
	return nil
}

// GetUserByUsername retrieves a user by username
func (r *PostgresRepository) GetUserByUsername(ctx context.Context, username string) (*User, error) {
	// Create telemetry span
	ctx, span := r.createSpan(ctx, "get_user_by_username")
	if span != nil {
		defer span.End()
		span.SetAttributes(attribute.String("username", username))
	}

	var user User
	result := r.db.WithContext(ctx).Where("username = ?", username).First(&user)
	if result.Error != nil {
		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
			return nil, nil
		}
		if span != nil {
			span.RecordError(result.Error)
		}
		return nil, fmt.Errorf("failed to get user by username: %w", result.Error)
	}
	return &user, nil
}

// GetUserByID retrieves a user by ID
func (r *PostgresRepository) GetUserByID(ctx context.Context, id uint) (*User, error) {
	var user User
	result := r.db.WithContext(ctx).First(&user, id)
	if result.Error != nil {
		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
			return nil, nil
		}
		return nil, fmt.Errorf("failed to get user by ID: %w", result.Error)
	}
	return &user, nil
}

// UpdateUser updates a user in the database
func (r *PostgresRepository) UpdateUser(ctx context.Context, user *User) error {
	result := r.db.WithContext(ctx).Save(user)
	if result.Error != nil {
		return fmt.Errorf("failed to update user: %w", result.Error)
	}
	return nil
}

// DeleteUser deletes a user from the database
func (r *PostgresRepository) DeleteUser(ctx context.Context, id uint) error {
	result := r.db.WithContext(ctx).Delete(&User{}, id)
	if result.Error != nil {
		return fmt.Errorf("failed to delete user: %w", result.Error)
	}
	return nil
}

// AllowPasswordReset flags a user for password reset
func (r *PostgresRepository) AllowPasswordReset(ctx context.Context, username string) error {
	user, err := r.GetUserByUsername(ctx, username)
	if err != nil {
		return fmt.Errorf("failed to get user for password reset: %w", err)
	}
	if user == nil {
		return fmt.Errorf("user not found: %s", username)
	}

	user.AllowPasswordReset = true
	return r.UpdateUser(ctx, user)
}

// CompletePasswordReset completes the password reset process
func (r *PostgresRepository) CompletePasswordReset(ctx context.Context, username, newPasswordHash string) error {
	user, err := r.GetUserByUsername(ctx, username)
	if err != nil {
		return fmt.Errorf("failed to get user for password reset completion: %w", err)
	}
	if user == nil {
		return fmt.Errorf("user not found: %s", username)
	}

	if !user.AllowPasswordReset {
		return fmt.Errorf("password reset not allowed for user: %s", username)
	}

	user.PasswordHash = newPasswordHash
	user.AllowPasswordReset = false
	return r.UpdateUser(ctx, user)
}

// UserExists checks if a user exists by username
func (r *PostgresRepository) UserExists(ctx context.Context, username string) (bool, error) {
	var count int64
	result := r.db.WithContext(ctx).Model(&User{}).Where("username = ?", username).Count(&count)
	if result.Error != nil {
		return false, fmt.Errorf("failed to check if user exists: %w", result.Error)
	}
	return count > 0, nil
}

// Close closes the database connection
func (r *PostgresRepository) Close() error {
	sqlDB, err := r.db.DB()
	if err != nil {
		return fmt.Errorf("failed to get database connection: %w", err)
	}
	return sqlDB.Close()
}

// CheckDatabaseHealth checks if the database is healthy and responsive
func (r *PostgresRepository) CheckDatabaseHealth(ctx context.Context) error {
	// Simple query to test database connectivity
	var count int64
	result := r.db.WithContext(ctx).Model(&User{}).Count(&count)
	if result.Error != nil {
		return fmt.Errorf("database health check failed: %w", result.Error)
	}
	return nil
}

// createSpan creates a new telemetry span if persistence telemetry is enabled
func (r *PostgresRepository) createSpan(ctx context.Context, operation string) (context.Context, trace.Span) {
	if r.config == nil || !r.config.GetPersistenceTelemetryEnabled() {
		return ctx, trace.SpanFromContext(ctx)
	}

	// Create a new span with the operation name
	spanName := r.spanPrefix + operation
	tr := otel.Tracer("user-repository")
	return tr.Start(ctx, spanName)
}