// Package logging provides structured logging with zap
package logging

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

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

	"github.com/konduktor/konduktor/internal/config"
)

// Config is a simple configuration for basic logger setup
type Config struct {
	Level           string
	TimestampFormat string
}

// Logger wraps zap.SugaredLogger with additional functionality
type Logger struct {
	*zap.SugaredLogger
	zap    *zap.Logger
	config *config.LoggingConfig
	name   string
}

// New creates a new Logger with basic configuration
func New(cfg Config) (*Logger, error) {
	level := parseLevel(cfg.Level)

	timestampFormat := cfg.TimestampFormat
	if timestampFormat == "" {
		timestampFormat = "2006-01-02 15:04:05"
	}

	encoderConfig := zap.NewProductionEncoderConfig()
	encoderConfig.TimeKey = "timestamp"
	encoderConfig.EncodeTime = zapcore.TimeEncoderOfLayout(timestampFormat)
	encoderConfig.EncodeLevel = zapcore.CapitalColorLevelEncoder

	core := zapcore.NewCore(
		zapcore.NewConsoleEncoder(encoderConfig),
		zapcore.AddSync(os.Stdout),
		level,
	)

	zapLogger := zap.New(core)
	return &Logger{
		SugaredLogger: zapLogger.Sugar(),
		zap:           zapLogger,
		name:          "konduktor",
	}, nil
}

// NewFromConfig creates a Logger from full LoggingConfig
func NewFromConfig(cfg config.LoggingConfig) (*Logger, error) {
	var cores []zapcore.Core

	// Parse main level
	mainLevel := parseLevel(cfg.Level)

	// Add console core if enabled
	if cfg.ConsoleOutput {
		consoleLevel := mainLevel
		if cfg.Console != nil && cfg.Console.Level != "" {
			consoleLevel = parseLevel(cfg.Console.Level)
		}

		var consoleEncoder zapcore.Encoder
		formatConfig := cfg.Format
		if cfg.Console != nil {
			formatConfig = mergeFormatConfig(cfg.Format, cfg.Console.Format)
		}

		encoderCfg := createEncoderConfig(formatConfig)
		if formatConfig.Type == "json" {
			consoleEncoder = zapcore.NewJSONEncoder(encoderCfg)
		} else {
			if formatConfig.UseColors {
				encoderCfg.EncodeLevel = zapcore.CapitalColorLevelEncoder
			}
			consoleEncoder = zapcore.NewConsoleEncoder(encoderCfg)
		}

		consoleSyncer := zapcore.AddSync(os.Stdout)
		cores = append(cores, zapcore.NewCore(consoleEncoder, consoleSyncer, consoleLevel))
	}

	// Add file cores
	for _, fileConfig := range cfg.Files {
		fileCore, err := createFileCore(fileConfig, cfg.Format, mainLevel)
		if err != nil {
			return nil, fmt.Errorf("failed to create file logger for %s: %w", fileConfig.Path, err)
		}

		// If specific loggers are configured, wrap with filter
		if len(fileConfig.Loggers) > 0 {
			fileCore = &filteredCore{
				Core:    fileCore,
				loggers: fileConfig.Loggers,
			}
		}

		cores = append(cores, fileCore)
	}

	// If no cores configured, add default console
	if len(cores) == 0 {
		encoderCfg := zap.NewProductionEncoderConfig()
		encoderCfg.EncodeTime = zapcore.TimeEncoderOfLayout("2006-01-02 15:04:05")
		encoderCfg.EncodeLevel = zapcore.CapitalColorLevelEncoder
		cores = append(cores, zapcore.NewCore(
			zapcore.NewConsoleEncoder(encoderCfg),
			zapcore.AddSync(os.Stdout),
			mainLevel,
		))
	}

	// Combine all cores
	core := zapcore.NewTee(cores...)
	zapLogger := zap.New(core, zap.AddCaller(), zap.AddCallerSkip(1))

	return &Logger{
		SugaredLogger: zapLogger.Sugar(),
		zap:           zapLogger,
		config:        &cfg,
		name:          "konduktor",
	}, nil
}

// Named returns a logger with a specific name (for filtering)
func (l *Logger) Named(name string) *Logger {
	return &Logger{
		SugaredLogger: l.SugaredLogger.Named(name),
		zap:           l.zap.Named(name),
		config:        l.config,
		name:          name,
	}
}

// With returns a logger with additional fields
func (l *Logger) With(args ...interface{}) *Logger {
	return &Logger{
		SugaredLogger: l.SugaredLogger.With(args...),
		zap:           l.zap.Sugar().With(args...).Desugar(),
		config:        l.config,
		name:          l.name,
	}
}

// Sync flushes any buffered log entries
func (l *Logger) Sync() error {
	return l.zap.Sync()
}

// GetZap returns the underlying zap.Logger
func (l *Logger) GetZap() *zap.Logger {
	return l.zap
}

// Debug logs a debug message
func (l *Logger) Debug(msg string, keysAndValues ...interface{}) {
	l.SugaredLogger.Debugw(msg, keysAndValues...)
}

// Info logs an info message
func (l *Logger) Info(msg string, keysAndValues ...interface{}) {
	l.SugaredLogger.Infow(msg, keysAndValues...)
}

// Warn logs a warning message
func (l *Logger) Warn(msg string, keysAndValues ...interface{}) {
	l.SugaredLogger.Warnw(msg, keysAndValues...)
}

// Error logs an error message
func (l *Logger) Error(msg string, keysAndValues ...interface{}) {
	l.SugaredLogger.Errorw(msg, keysAndValues...)
}

// Fatal logs a fatal message and exits
func (l *Logger) Fatal(msg string, keysAndValues ...interface{}) {
	l.SugaredLogger.Fatalw(msg, keysAndValues...)
}

// --- Helper functions ---

func parseLevel(level string) zapcore.Level {
	switch strings.ToUpper(level) {
	case "DEBUG":
		return zapcore.DebugLevel
	case "INFO":
		return zapcore.InfoLevel
	case "WARN", "WARNING":
		return zapcore.WarnLevel
	case "ERROR":
		return zapcore.ErrorLevel
	case "CRITICAL", "FATAL":
		return zapcore.FatalLevel
	default:
		return zapcore.InfoLevel
	}
}

func createEncoderConfig(format config.LogFormatConfig) zapcore.EncoderConfig {
	timestampFormat := format.TimestampFormat
	if timestampFormat == "" {
		timestampFormat = "2006-01-02 15:04:05"
	}

	cfg := zapcore.EncoderConfig{
		TimeKey:        "timestamp",
		LevelKey:       "level",
		NameKey:        "logger",
		CallerKey:      "caller",
		FunctionKey:    zapcore.OmitKey,
		MessageKey:     "msg",
		StacktraceKey:  "stacktrace",
		LineEnding:     zapcore.DefaultLineEnding,
		EncodeLevel:    zapcore.CapitalLevelEncoder,
		EncodeTime:     zapcore.TimeEncoderOfLayout(timestampFormat),
		EncodeDuration: zapcore.SecondsDurationEncoder,
		EncodeCaller:   zapcore.ShortCallerEncoder,
	}

	if !format.ShowModule {
		cfg.NameKey = zapcore.OmitKey
	}

	return cfg
}

func mergeFormatConfig(base, override config.LogFormatConfig) config.LogFormatConfig {
	result := base
	if override.Type != "" {
		result.Type = override.Type
	}
	if override.TimestampFormat != "" {
		result.TimestampFormat = override.TimestampFormat
	}
	// UseColors and ShowModule are bool - check if override has non-default
	result.UseColors = override.UseColors
	result.ShowModule = override.ShowModule
	return result
}

func createFileCore(fileConfig config.FileLogConfig, defaultFormat config.LogFormatConfig, defaultLevel zapcore.Level) (zapcore.Core, error) {
	// Ensure directory exists
	dir := filepath.Dir(fileConfig.Path)
	if dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0755); err != nil {
			return nil, fmt.Errorf("failed to create log directory %s: %w", dir, err)
		}
	}

	// Configure log rotation with lumberjack
	maxSize := 10 // MB
	if fileConfig.MaxBytes > 0 {
		maxSize = int(fileConfig.MaxBytes / (1024 * 1024))
		if maxSize < 1 {
			maxSize = 1
		}
	}

	backupCount := 5
	if fileConfig.BackupCount > 0 {
		backupCount = fileConfig.BackupCount
	}

	rotator := &lumberjack.Logger{
		Filename:   fileConfig.Path,
		MaxSize:    maxSize,
		MaxBackups: backupCount,
		MaxAge:     30, // days
		Compress:   true,
	}

	// Determine level
	level := defaultLevel
	if fileConfig.Level != "" {
		level = parseLevel(fileConfig.Level)
	}

	// Create encoder
	format := defaultFormat
	if fileConfig.Format.Type != "" {
		format = mergeFormatConfig(defaultFormat, fileConfig.Format)
	}
	// Files should not use colors
	format.UseColors = false

	encoderConfig := createEncoderConfig(format)
	var encoder zapcore.Encoder
	if format.Type == "json" {
		encoder = zapcore.NewJSONEncoder(encoderConfig)
	} else {
		encoder = zapcore.NewConsoleEncoder(encoderConfig)
	}

	return zapcore.NewCore(encoder, zapcore.AddSync(rotator), level), nil
}

// filteredCore wraps a Core to filter by logger name
type filteredCore struct {
	zapcore.Core
	loggers []string
}

func (c *filteredCore) Check(entry zapcore.Entry, ce *zapcore.CheckedEntry) *zapcore.CheckedEntry {
	if !c.shouldLog(entry.LoggerName) {
		return ce
	}
	return c.Core.Check(entry, ce)
}

func (c *filteredCore) shouldLog(loggerName string) bool {
	if len(c.loggers) == 0 {
		return true
	}

	for _, allowed := range c.loggers {
		if loggerName == allowed || strings.HasPrefix(loggerName, allowed+".") {
			return true
		}
	}
	return false
}

func (c *filteredCore) With(fields []zapcore.Field) zapcore.Core {
	return &filteredCore{
		Core:    c.Core.With(fields),
		loggers: c.loggers,
	}
}