package logger

import (
	"bytes"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"
)

// TODO: Enable turning colors on and off maybe even per stream?

var loglevel = flag.String("loglevel", "info", "log level")

// LogLevel defines the severity of log messages
type LogLevel int

const (
	// LevelError is for critical errors that should always be displayed
	LevelError LogLevel = iota
	// LevelWarning is for important warnings
	LevelWarning
	// LevelInfo is for informational messages
	LevelInfo
	// LevelDebug is for detailed debugging information
	LevelDebug
	// LevelTrace is for very detailed tracing information
	LevelTrace
	// LevelLua is specifically for output from Lua scripts
	LevelLua
	LevelPrefix
)

var levelNames = map[LogLevel]string{
	LevelError:   "ERROR",
	LevelWarning: "WARNING",
	LevelInfo:    "INFO",
	LevelDebug:   "DEBUG",
	LevelTrace:   "TRACE",
	LevelLua:     "LUA",
	LevelPrefix:  "PREFIX",
}

var levelColors = map[LogLevel]string{
	LevelError:   "\033[1;31m", // Bold Red
	LevelWarning: "\033[1;33m", // Bold Yellow
	LevelInfo:    "\033[1;32m", // Bold Green
	LevelDebug:   "\033[1;36m", // Bold Cyan
	LevelTrace:   "\033[1;35m", // Bold Magenta
	LevelLua:     "\033[1;34m", // Bold Blue
	LevelPrefix:  "\033[0;90m", // Regular Dark Grey
}

// ANSI Background Colors
var levelBackgroundColors = map[LogLevel]string{
	LevelError:   "\033[41m", // Red Background
	LevelWarning: "\033[43m", // Yellow Background
}

// ANSI Foreground Colors (adjusting for readability on backgrounds)
const FgWhiteBold = "\033[1;37m"

// ResetColor is the ANSI code to reset text color
const ResetColor = "\033[0m"

// Logger is our custom logger with level support
type Logger struct {
	mu            sync.Mutex
	out           io.Writer
	currentLevel  LogLevel
	prefix        string
	userPrefix    string
	flag          int
	useColors     bool
	callerOffset  int
	defaultFields map[string]interface{}
	showGoroutine bool
}

var (
	// Default is the global logger instance
	Default *Logger
	// defaultLogLevel is the default log level if not specified
	defaultLogLevel = LevelInfo
	// Global mutex for DefaultLogger initialization
	initMutex sync.Mutex
)

// ParseLevel converts a string log level to LogLevel
func ParseLevel(levelStr string) LogLevel {
	switch strings.ToUpper(levelStr) {
	case "ERROR":
		return LevelError
	case "WARNING", "WARN":
		return LevelWarning
	case "INFO":
		return LevelInfo
	case "DEBUG":
		return LevelDebug
	case "TRACE":
		return LevelTrace
	case "LUA":
		return LevelLua
	default:
		return defaultLogLevel
	}
}

// String returns the string representation of the log level
func (l LogLevel) String() string {
	if name, ok := levelNames[l]; ok {
		return name
	}
	return fmt.Sprintf("Level(%d)", l)
}

// New creates a new Logger instance
func New(out io.Writer, prefix string, flag int) *Logger {
	return &Logger{
		out:           out,
		currentLevel:  defaultLogLevel,
		prefix:        prefix,
		userPrefix:    "",
		flag:          flag,
		useColors:     true,
		callerOffset:  0,
		defaultFields: make(map[string]interface{}),
		showGoroutine: true,
	}
}

func InitFlag() {
	level := ParseLevel(*loglevel)
	Init(level)
}

// Init initializes the DefaultLogger
func Init(level LogLevel) {
	initMutex.Lock()
	defer initMutex.Unlock()

	if Default == nil {
		Default = New(os.Stdout, "", log.Lmicroseconds|log.Lshortfile)
	}
	Default.SetLevel(level)
}

// SetLevel sets the current log level
func (l *Logger) SetLevel(level LogLevel) {
	l.mu.Lock()
	defer l.mu.Unlock()
	l.currentLevel = level
}

// GetLevel returns the current log level
func (l *Logger) GetLevel() LogLevel {
	l.mu.Lock()
	defer l.mu.Unlock()
	return l.currentLevel
}

// SetCallerOffset sets the caller offset for correct file and line reporting
func (l *Logger) SetCallerOffset(offset int) {
	l.mu.Lock()
	defer l.mu.Unlock()
	l.callerOffset = offset
}

// SetShowGoroutine sets whether to include goroutine ID in log messages
func (l *Logger) SetShowGoroutine(show bool) {
	l.mu.Lock()
	defer l.mu.Unlock()
	l.showGoroutine = show
}

// ShowGoroutine returns whether goroutine ID is included in log messages
func (l *Logger) ShowGoroutine() bool {
	l.mu.Lock()
	defer l.mu.Unlock()
	return l.showGoroutine
}

// WithField adds a field to the logger's context
func (l *Logger) WithField(key string, value interface{}) *Logger {
	newLogger := &Logger{
		out:           l.out,
		currentLevel:  l.currentLevel,
		prefix:        l.prefix,
		userPrefix:    l.userPrefix,
		flag:          l.flag,
		useColors:     l.useColors,
		callerOffset:  l.callerOffset,
		defaultFields: make(map[string]interface{}),
		showGoroutine: l.showGoroutine,
	}

	// Copy existing fields
	for k, v := range l.defaultFields {
		newLogger.defaultFields[k] = v
	}

	// Add new field
	newLogger.defaultFields[key] = value
	return newLogger
}

// WithFields adds multiple fields to the logger's context
func (l *Logger) WithFields(fields map[string]interface{}) *Logger {
	newLogger := &Logger{
		out:           l.out,
		currentLevel:  l.currentLevel,
		prefix:        l.prefix,
		userPrefix:    l.userPrefix,
		flag:          l.flag,
		useColors:     l.useColors,
		callerOffset:  l.callerOffset,
		defaultFields: make(map[string]interface{}),
		showGoroutine: l.showGoroutine,
	}

	// Copy existing fields
	for k, v := range l.defaultFields {
		newLogger.defaultFields[k] = v
	}

	// Add new fields
	for k, v := range fields {
		newLogger.defaultFields[k] = v
	}
	return newLogger
}

func (l *Logger) WithPrefix(prefix string) *Logger {
	if Default == nil {
		Init(defaultLogLevel)
	}
	if l == nil {
		l = Default
	}
	newLogger := &Logger{
		out:           l.out,
		currentLevel:  l.currentLevel,
		prefix:        l.prefix,
		userPrefix:    strings.TrimSpace(l.userPrefix + " " + prefix),
		flag:          l.flag,
		useColors:     l.useColors,
		callerOffset:  l.callerOffset,
		defaultFields: make(map[string]interface{}),
		showGoroutine: l.showGoroutine,
	}

	// Copy existing fields
	for k, v := range l.defaultFields {
		newLogger.defaultFields[k] = v
	}
	return newLogger
}

func (l *Logger) ToFile(filename string) *Logger {
	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
	if err != nil {
		log.Fatal(err)
	}
	if Default == nil {
		Init(defaultLogLevel)
	}
	if l == nil {
		l = Default
	}
	newLogger := &Logger{
		out:           io.MultiWriter(l.out, file),
		currentLevel:  l.currentLevel,
		prefix:        l.prefix,
		userPrefix:    l.userPrefix,
		flag:          l.flag,
		useColors:     l.useColors,
		callerOffset:  l.callerOffset,
		defaultFields: make(map[string]interface{}),
		showGoroutine: l.showGoroutine,
	}
	return newLogger
}

// GetGoroutineID extracts the goroutine ID from the runtime stack
func GetGoroutineID() string {
	buf := make([]byte, 64)
	n := runtime.Stack(buf, false)
	// Format of first line is "goroutine N [state]:"
	// We only need the N part
	buf = buf[:n]
	idField := bytes.Fields(bytes.Split(buf, []byte{':'})[0])[1]
	return string(idField)
}

// formatMessage formats a log message with level, time, file, and line information
func (l *Logger) formatMessage(level LogLevel, format string, args ...interface{}) string {
	var msg string
	if len(args) > 0 {
		msg = fmt.Sprintf(format, args...)
	} else {
		msg = format
	}

	// Format default fields if any
	var fields string
	if len(l.defaultFields) > 0 {
		var pairs []string
		for k, v := range l.defaultFields {
			pairs = append(pairs, fmt.Sprintf("%s=%v", k, v))
		}
		fields = " " + strings.Join(pairs, " ")
	}

	var levelColor, bgColor, msgFgColor, resetColor string
	useBgColor := false // Flag to indicate if background color should be used
	if l.useColors {
		resetColor = ResetColor
		levelColor = levelColors[level] // Color for the level tag text ONLY

		if bg, ok := levelBackgroundColors[level]; ok { // Check if this level has a background color defined (ERROR/WARNING)
			bgColor = bg
			msgFgColor = FgWhiteBold // Use bold white for the message part on colored background
			useBgColor = true
		} else {
			// For other levels, message part uses default terminal color.
			// msgFgColor remains empty, bgColor remains empty.
			// levelColor is still needed for the tag below.
		}
	}

	var caller string
	if l.flag&log.Lshortfile != 0 || l.flag&log.Llongfile != 0 {
		// Find the actual caller by scanning up the stack
		// until we find a function outside the logger package
		var file string
		var line int
		var ok bool

		// Start at a reasonable depth and scan up to 10 frames
		for depth := 4; depth < 15; depth++ {
			_, file, line, ok = runtime.Caller(depth)
			if !ok {
				break
			}

			// If the caller is not in the logger package, we found our caller
			if !strings.Contains(file, "logger/logger.go") {
				break
			}
		}

		if !ok {
			file = "???"
			line = 0
		}

		if l.flag&log.Lshortfile != 0 {
			file = filepath.Base(file)
		}
		caller = fmt.Sprintf("%-25s ", file+":"+strconv.Itoa(line))
	}

	// Format the timestamp with fixed width
	var timeStr string
	if l.flag&(log.Ldate|log.Ltime|log.Lmicroseconds) != 0 {
		t := time.Now()
		if l.flag&log.Ldate != 0 {
			timeStr += fmt.Sprintf("%04d/%02d/%02d ", t.Year(), t.Month(), t.Day())
		}
		if l.flag&(log.Ltime|log.Lmicroseconds) != 0 {
			timeStr += fmt.Sprintf("%02d:%02d:%02d", t.Hour(), t.Minute(), t.Second())
			if l.flag&log.Lmicroseconds != 0 {
				timeStr += fmt.Sprintf(".%06d", t.Nanosecond()/1000)
			}
		}
		timeStr = fmt.Sprintf("%-15s ", timeStr)
	}

	// Add goroutine ID if enabled, with fixed width
	var goroutineStr string
	if l.showGoroutine {
		goroutineID := GetGoroutineID()
		goroutineStr = fmt.Sprintf("[g:%-4s] ", goroutineID)
	}

	// Create a colored level indicator - color only the level name text, reset locally
	levelStr := fmt.Sprintf("%s%s%s", levelColor, levelNames[level], resetColor)
	levelColumn := fmt.Sprintf("%-20s", levelStr) // Pad the tag

	userPrefixStr := ""
	if l.userPrefix != "" {
		// Use default foreground color for prefix (dark grey), reset locally
		prefixColor := levelColors[LevelPrefix]
		userPrefixStr = fmt.Sprintf("%s[%s]%s ", prefixColor, l.userPrefix, resetColor)
	}

	// Build the prefix part (timestamp, caller, goroutine, level tag, user prefix)
	// These parts will use default terminal colors or their specifically set colors (like level tag)
	prefixPart := fmt.Sprintf("%s%s%s%s%s%s",
		l.prefix, timeStr, caller, goroutineStr, levelColumn, userPrefixStr)

	// Build the message part
	messagePart := fmt.Sprintf("%s%s", msg, fields)

	// Combine prefix and message, applying background/foreground ONLY to the message part
	if useBgColor {
		// Apply background and specific foreground ONLY to the message part
		return fmt.Sprintf("%s%s%s%s%s", prefixPart, bgColor, msgFgColor, messagePart, resetColor)
	} else {
		// For non-ERROR/WARNING, just combine prefix (with its colored tag) and the uncolored message part.
		// No additional color codes needed here for the message itself.
		return fmt.Sprintf("%s%s", prefixPart, messagePart)
	}
}

// log logs a message at the specified level
func (l *Logger) log(level LogLevel, format string, args ...interface{}) {
	// Always show LUA level logs regardless of the current log level
	if level != LevelLua && level > l.currentLevel {
		return
	}

	l.mu.Lock()
	defer l.mu.Unlock()

	// Get formatted message with potential background color
	msg := l.formatMessage(level, format, args...)
	fmt.Fprintln(l.out, msg)
}

// Error logs an error message
func (l *Logger) Error(format string, args ...interface{}) {
	l.log(LevelError, format, args...)
}

// Warning logs a warning message
func (l *Logger) Warning(format string, args ...interface{}) {
	l.log(LevelWarning, format, args...)
}

// Info logs an informational message
func (l *Logger) Info(format string, args ...interface{}) {
	l.log(LevelInfo, format, args...)
}

// Debug logs a debug message
func (l *Logger) Debug(format string, args ...interface{}) {
	l.log(LevelDebug, format, args...)
}

// Trace logs a trace message
func (l *Logger) Trace(format string, args ...interface{}) {
	l.log(LevelTrace, format, args...)
}

// Lua logs a Lua message
func (l *Logger) Lua(format string, args ...interface{}) {
	l.log(LevelLua, format, args...)
}

// Global log functions that use DefaultLogger

// Error logs an error message using the default logger
func Error(format string, args ...interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.Error(format, args...)
}

// Warning logs a warning message using the default logger
func Warning(format string, args ...interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.Warning(format, args...)
}

// Info logs an informational message using the default logger
func Info(format string, args ...interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.Info(format, args...)
}

// Debug logs a debug message using the default logger
func Debug(format string, args ...interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.Debug(format, args...)
}

// Trace logs a trace message using the default logger
func Trace(format string, args ...interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.Trace(format, args...)
}

// Lua logs a Lua message using the default logger
func Lua(format string, args ...interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.Lua(format, args...)
}

// LogPanic logs a panic error and its stack trace
func LogPanic(r interface{}) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	stack := make([]byte, 4096)
	n := runtime.Stack(stack, false)
	Default.Error("PANIC: %v\n%s", r, stack[:n])
}

// SetLevel sets the log level for the default logger
func SetLevel(level LogLevel) {
	if Default == nil {
		Init(level)
		return
	}
	Default.SetLevel(level)
}

// GetLevel gets the log level for the default logger
func GetLevel() LogLevel {
	if Default == nil {
		Init(defaultLogLevel)
	}
	return Default.GetLevel()
}

// WithField returns a new logger with the field added to the default logger's context
func WithField(key string, value interface{}) *Logger {
	if Default == nil {
		Init(defaultLogLevel)
	}
	return Default.WithField(key, value)
}

// WithFields returns a new logger with the fields added to the default logger's context
func WithFields(fields map[string]interface{}) *Logger {
	if Default == nil {
		Init(defaultLogLevel)
	}
	return Default.WithFields(fields)
}

// SetShowGoroutine enables or disables goroutine ID display in the default logger
func SetShowGoroutine(show bool) {
	if Default == nil {
		Init(defaultLogLevel)
	}
	Default.SetShowGoroutine(show)
}

// ShowGoroutine returns whether goroutine ID is included in default logger's messages
func ShowGoroutine() bool {
	if Default == nil {
		Init(defaultLogLevel)
	}
	return Default.ShowGoroutine()
}