package utils

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"sync"
	"time"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
	"gopkg.in/yaml.v2"
)

var (
	Log    *zap.Logger
	once   sync.Once
	config Config
)

type Config struct {
	Logging struct {
		Level      string `yaml:"level"`
		Encoding   string `yaml:"encoding"`
		OutputPath string `yaml:"outputPath"`
		File       struct {
			MaxSize    int  `yaml:"maxSize"`
			MaxBackups int  `yaml:"maxBackups"`
			MaxAge     int  `yaml:"maxAge"`
			Compress   bool `yaml:"compress"`
		} `yaml:"file"`
		EncoderConfig struct {
			MessageKey    string `yaml:"messageKey"`
			LevelKey      string `yaml:"levelKey"`
			TimeKey       string `yaml:"timeKey"`
			NameKey       string `yaml:"nameKey"`
			CallerKey     string `yaml:"callerKey"`
			FunctionKey   string `yaml:"functionKey"`
			StacktraceKey string `yaml:"stacktraceKey"`
			EncodeTime    string `yaml:"timeEncoder"`
			EncodeLevel   string `yaml:"levelEncoder"`
		} `yaml:"encoderConfig"`
	} `yaml:"logging"`
}

func InitLogger() error {
	var err error
	once.Do(func() {
		err = loadLoggerConfig()
	})
	return err
}

func loadLoggerConfig() error {
	// read logger configuration file
	configPath := filepath.Join(Global_TopDir, "config", "logger.yaml")

	// validate the yaml file format
	data, err := ValidateYamlFormat(configPath)
	if err != nil {
		DiagnoseLogCreationError("Fail to call DiagnoseLogCreationError with error", err)
		return err
	}
	if data == nil {
		err = errors.New("invalid logger.yaml file")
		DiagnoseLogCreationError("Fail to call ValidateYamlFormat and data is nil", err)
		return err
	}

	if err := yaml.Unmarshal(data, &config); err != nil {
		DiagnoseLogCreationError("Failed to parse logger configuration file", err)
		return err
	}

	// Handle both formats for OutputPath
	if !filepath.IsAbs(config.Logging.OutputPath) {
		// If OutputPath is relative, prepend the logs directory
		config.Logging.OutputPath = filepath.Join(Global_TopDir, "logs", config.Logging.OutputPath)
	}

	// Get the directory from the absolute path
	logFilePath := config.Logging.OutputPath // it store the absolute path
	logDir := filepath.Dir(logFilePath)      // Extract the directory
	// Create the directory if it does not exist
	if err := os.MkdirAll(logDir, 0755); err != nil {
		DiagnoseLogCreationError("Failed to create logs directory", err)
		return err
	}

	Log, err = createLogger(config)
	if err != nil {
		DiagnoseLogCreationError("Failed to create logger", err)
		return err
	}
	return nil
}

func createLogger(config Config) (*zap.Logger, error) {
	configLevel, err := zapcore.ParseLevel(config.Logging.Level)
	if err != nil {
		return nil, err
	}

	// create log file and set the permission
	file, err := os.OpenFile(config.Logging.OutputPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
	if err != nil {
		return nil, err
	}
	file.Close()

	// configure lumberjack for log rotation
	logWriter := &lumberjack.Logger{
		Filename:   config.Logging.OutputPath,
		MaxSize:    config.Logging.File.MaxSize,
		MaxBackups: config.Logging.File.MaxBackups,
		MaxAge:     config.Logging.File.MaxAge,
		Compress:   config.Logging.File.Compress,
	}

	// Create cores for different log levels
	core := zapcore.NewCore(
		zapcore.NewConsoleEncoder(zapcore.EncoderConfig{
			MessageKey:       config.Logging.EncoderConfig.MessageKey,
			LevelKey:         config.Logging.EncoderConfig.LevelKey,
			TimeKey:          config.Logging.EncoderConfig.TimeKey,
			NameKey:          config.Logging.EncoderConfig.NameKey,
			CallerKey:        config.Logging.EncoderConfig.CallerKey,
			StacktraceKey:    "", // disable stacktrace
			EncodeTime:       zapcore.ISO8601TimeEncoder,
			EncodeLevel:      zapcore.CapitalLevelEncoder,
			EncodeCaller:     zapcore.ShortCallerEncoder,
			ConsoleSeparator: " ",
		}),
		zapcore.AddSync(logWriter),
		configLevel,
	)
	logger := zap.New(core,
		zap.AddCaller(),                   // caller info
		zap.AddStacktrace(zap.ErrorLevel), // show error stacktrace
		zap.AddCallerSkip(1),              // skip one layer of caller
	)
	return logger, nil

}

func Info(msg string, fields ...zap.Field) {
	Log.WithOptions(zap.WithCaller(false)).Info(msg, fields...)
}
func Error(msg string, fields ...zap.Field) {
	Log.WithOptions(zap.WithCaller(false)).Error(msg, fields...)
}

func Warn(msg string, fields ...zap.Field) {
	Log.WithOptions(zap.WithCaller(false)).Warn(msg, fields...)
}

func Debug(msg string, fields ...zap.Field) {
	Log.WithOptions(zap.WithCaller(true)).Debug(msg, fields...)
}

func Fatal(msg string, fields ...zap.Field) {
	Log.WithOptions(zap.WithCaller(false)).Fatal(msg, fields...)
}

// DiagnoseLogCreationError is a helper function to diagnose the error when creating log file
func DiagnoseLogCreationError(context string, err error) {
	// construct the error message
	logMsg := fmt.Sprintf("[%s] %s: %v\n", time.Now().Format("2006-01-02 15:04:05"), context, err)
	// define logger_error.log file path
	logFilePath := filepath.Join(Global_TopDir, "logs", "logger_error.log")
	// open log file
	f, fileErr := os.OpenFile(logFilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if fileErr != nil {
		fmt.Printf("Failed to open logger_error.log: %v\n", fileErr)
		// if failed to open log file, print the error message to console
		fmt.Print(logMsg)
		return
	}
	defer f.Close()
	// write the error message
	if _, writeErr := f.WriteString(logMsg); writeErr != nil {
		fmt.Printf("Failed to write to logger_error.log: %v\n", writeErr)
		// if failed to write to log file, print the error message to console
		fmt.Print(logMsg)
	}
}