package logger

import (
	"io"
	"os"
	"path/filepath"
	"regexp"
	"sync"

	"github.com/sirupsen/logrus"
)

var (
	Log  *logrus.Logger
	once sync.Once
	mu   sync.RWMutex
)

// Config holds logging configuration
type Config struct {
	Level      string `yaml:"level"`       // debug, info, warn, error
	Format     string `yaml:"format"`      // json, text
	File       string `yaml:"file"`        // log file path (empty for stdout)
	MaxSize    int    `yaml:"max_size"`    // max log file size in MB
	MaxBackups int    `yaml:"max_backups"` // max number of backup files
	MaxAge     int    `yaml:"max_age"`     // max age of backup files in days
	Compress   bool   `yaml:"compress"`    // compress backup files
}

// Init initializes the global logger with the given configuration
func Init(config Config) error {
	mu.Lock()
	defer mu.Unlock()

	Log = logrus.New()

	// Set log level
	level, err := logrus.ParseLevel(config.Level)
	if err != nil {
		level = logrus.InfoLevel
	}
	Log.SetLevel(level)

	// Set log format with sanitization
	switch config.Format {
	case "json":
		Log.SetFormatter(&SanitizedJSONFormatter{
			TimestampFormat: "2006-01-02 15:04:05",
		})
	default:
		Log.SetFormatter(&SanitizedTextFormatter{
			FullTimestamp:   true,
			TimestampFormat: "2006-01-02 15:04:05",
		})
	}

	// Set output
	if config.File != "" {
		// Ensure directory exists
		dir := filepath.Dir(config.File)
		if err := os.MkdirAll(dir, 0755); err != nil {
			return err
		}

		// Open log file with secure permissions (owner read/write only)
		file, err := os.OpenFile(config.File, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0600)
		if err != nil {
			return err
		}

		// Set output to both file and stdout
		Log.SetOutput(io.MultiWriter(file, os.Stdout))
	} else {
		Log.SetOutput(os.Stdout)
	}

	return nil
}

// GetLogger returns the global logger instance
func GetLogger() *logrus.Logger {
	mu.RLock()
	if Log != nil {
		mu.RUnlock()
		return Log
	}
	mu.RUnlock()

	// Initialize with default config if not already initialized
	once.Do(func() {
		Init(Config{
			Level:  "info",
			Format: "text",
			File:   "",
		})
	})

	mu.RLock()
	defer mu.RUnlock()
	return Log
}

// Helper functions for common logging operations
func Debug(args ...interface{}) {
	GetLogger().Debug(args...)
}

func Debugf(format string, args ...interface{}) {
	GetLogger().Debugf(format, args...)
}

func Info(args ...interface{}) {
	GetLogger().Info(args...)
}

func Infof(format string, args ...interface{}) {
	GetLogger().Infof(format, args...)
}

func Warn(args ...interface{}) {
	GetLogger().Warn(args...)
}

func Warnf(format string, args ...interface{}) {
	GetLogger().Warnf(format, args...)
}

func Error(args ...interface{}) {
	GetLogger().Error(args...)
}

func Errorf(format string, args ...interface{}) {
	GetLogger().Errorf(format, args...)
}

func Fatal(args ...interface{}) {
	GetLogger().Fatal(args...)
}

func Fatalf(format string, args ...interface{}) {
	GetLogger().Fatalf(format, args...)
}

// WithField creates a new logger entry with a field
func WithField(key string, value interface{}) *logrus.Entry {
	return GetLogger().WithField(key, value)
}

// WithFields creates a new logger entry with multiple fields
func WithFields(fields logrus.Fields) *logrus.Entry {
	return GetLogger().WithFields(fields)
}

// SanitizedTextFormatter sanitizes log output
type SanitizedTextFormatter struct {
	FullTimestamp   bool
	TimestampFormat string
}

// Format formats the log entry with sanitization
func (f *SanitizedTextFormatter) Format(entry *logrus.Entry) ([]byte, error) {
	// Sanitize sensitive data
	sanitizedEntry := *entry
	sanitizedEntry.Message = sanitizeString(entry.Message)

	// Sanitize fields
	sanitizedFields := make(logrus.Fields)
	for k, v := range entry.Data {
		sanitizedFields[k] = sanitizeValue(v)
	}
	sanitizedEntry.Data = sanitizedFields

	// Use default text formatter
	formatter := &logrus.TextFormatter{
		FullTimestamp:   f.FullTimestamp,
		TimestampFormat: f.TimestampFormat,
	}
	return formatter.Format(&sanitizedEntry)
}

// SanitizedJSONFormatter sanitizes JSON log output
type SanitizedJSONFormatter struct {
	TimestampFormat string
}

// Format formats the log entry with sanitization
func (f *SanitizedJSONFormatter) Format(entry *logrus.Entry) ([]byte, error) {
	// Sanitize sensitive data
	sanitizedEntry := *entry
	sanitizedEntry.Message = sanitizeString(entry.Message)

	// Sanitize fields
	sanitizedFields := make(logrus.Fields)
	for k, v := range entry.Data {
		sanitizedFields[k] = sanitizeValue(v)
	}
	sanitizedEntry.Data = sanitizedFields

	// Use default JSON formatter
	formatter := &logrus.JSONFormatter{
		TimestampFormat: f.TimestampFormat,
	}
	return formatter.Format(&sanitizedEntry)
}

// sanitizeString removes or masks sensitive information
func sanitizeString(s string) string {
	// Remove potential encryption keys (hex strings longer than 32 chars)
	keyPattern := regexp.MustCompile(`[a-fA-F0-9]{32,}`)
	s = keyPattern.ReplaceAllString(s, "[REDACTED_KEY]")

	// Remove potential passwords and tokens
	passwordPattern := regexp.MustCompile(`(?i)(password|pass|pwd|secret|key|token|auth|credential)\s*[:=]\s*[^\s]+`)
	s = passwordPattern.ReplaceAllString(s, "$1=[REDACTED]")

	// Remove potential API keys and tokens
	apiKeyPattern := regexp.MustCompile(`(?i)(api[_-]?key|access[_-]?token|bearer[_-]?token)\s*[:=]\s*[^\s]+`)
	s = apiKeyPattern.ReplaceAllString(s, "$1=[REDACTED]")

	// Remove potential database connection strings
	dbPattern := regexp.MustCompile(`(?i)(mysql|postgres|mongodb|redis)://[^@]+@[^\s]+`)
	s = dbPattern.ReplaceAllString(s, "[REDACTED_DB_CONNECTION]")

	// Remove potential JWT tokens
	jwtPattern := regexp.MustCompile(`eyJ[A-Za-z0-9_-]*\.[A-Za-z0-9_-]*\.[A-Za-z0-9_-]*`)
	s = jwtPattern.ReplaceAllString(s, "[REDACTED_JWT]")

	// Remove potential credit card numbers
	ccPattern := regexp.MustCompile(`\b\d{4}[-\s]?\d{4}[-\s]?\d{4}[-\s]?\d{4}\b`)
	s = ccPattern.ReplaceAllString(s, "[REDACTED_CC]")

	// Remove potential SSNs
	ssnPattern := regexp.MustCompile(`\b\d{3}-\d{2}-\d{4}\b`)
	s = ssnPattern.ReplaceAllString(s, "[REDACTED_SSN]")

	// Remove potential IP addresses in sensitive contexts
	ipPattern := regexp.MustCompile(`\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b`)
	s = ipPattern.ReplaceAllString(s, "[REDACTED_IP]")

	// Remove potential email addresses
	emailPattern := regexp.MustCompile(`\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b`)
	s = emailPattern.ReplaceAllString(s, "[REDACTED_EMAIL]")

	return s
}

// sanitizeValue sanitizes various value types
func sanitizeValue(v interface{}) interface{} {
	switch val := v.(type) {
	case string:
		return sanitizeString(val)
	case []byte:
		return "[BINARY_DATA]"
	case map[string]interface{}:
		sanitized := make(map[string]interface{})
		for k, v := range val {
			sanitized[k] = sanitizeValue(v)
		}
		return sanitized
	case []interface{}:
		sanitized := make([]interface{}, len(val))
		for i, v := range val {
			sanitized[i] = sanitizeValue(v)
		}
		return sanitized
	default:
		return v
	}
}