package sneklog

import (
	"errors"
	"fmt"
	"io"
	"strings"
)

type replacer struct {
	old string
	new string
}

func (r replacer) replace(s string) string {
	return strings.ReplaceAll(s, r.old, r.new)
}

// Logger routes log records to one or more configured writers.
type Logger struct {
	prefix    string
	level     LogLevel
	writers   []LoggerWriter
	replacers []replacer

	jsonPretty bool
}

// LogLevel describes a logging severity.
type LogLevel struct {
	n  uint8
	t  string
	fg FgColor
	bg BgColor
}

// GetName returns the lowercase textual representation of the level.
func (l *LogLevel) GetName() string     { return l.t }
func (l *LogLevel) GetFgColor() FgColor { return l.fg }
func (l *LogLevel) SetFgColor(color FgColor) *LogLevel {
	l.fg = color
	return l
}
func (l *LogLevel) GetBgColor() BgColor { return l.bg }
func (l *LogLevel) SetBgColor(color BgColor) *LogLevel {
	l.bg = color
	return l
}

// MethodTraceback describes a single stack frame attached to a log entry.
type MethodTraceback struct {
	Method    string `json:"method"`
	Filename  string `json:"filename"`
	Line      int    `json:"line"`
	Signature string `json:"signature"`
	FullPath  string `json:"fullPath"`
}

// Predefined log levels.
var (
	INFO  = LogLevel{n: 0, t: "info", fg: FgWhite}
	WARN  = LogLevel{n: 1, t: "warn", fg: FgHiYellow}
	ERROR = LogLevel{n: 2, t: "error", fg: FgHiRed}
	FATAL = LogLevel{n: 3, t: "fatal", fg: FgRed}
	DEBUG = LogLevel{n: 4, t: "debug", fg: FgGreen}
)

// CreateLogger creates a logger with default settings.
func CreateLogger() *Logger {
	return &Logger{
		prefix: "LOG",
		level:  FATAL,
	}
}

// Prefix sets the record prefix and returns the logger for chaining.
func (l *Logger) Prefix(prefix string) *Logger {
	l.prefix = prefix
	return l
}

// Level sets the maximum enabled level and returns the logger for chaining.
func (l *Logger) Level(level LogLevel) *Logger {
	l.level = level
	return l
}

// JsonPretty enables indented JSON output for JSON writers.
func (l *Logger) JsonPretty(b bool) *Logger {
	l.jsonPretty = b
	return l
}

// AddWriters appends multiple writers to the logger.
func (l *Logger) AddWriters(writers ...LoggerWriter) *Logger {
	l.writers = append(l.writers, writers...)
	return l
}

// AddWriter appends a single writer to the logger.
func (l *Logger) AddWriter(writer LoggerWriter) *Logger {
	l.writers = append(l.writers, writer)
	return l
}

// AddReplacer appends a message replacer and returns the logger for chaining.
//
// Replacement rules are applied before records are passed to writers. Empty old
// values are ignored because replacing an empty string would insert the
// replacement between every UTF-8 sequence.
func (l *Logger) AddReplacer(old, new string) *Logger {
	if old == "" {
		return l
	}
	r := replacer{old: old, new: new}
	l.replacers = append(l.replacers, r)
	return l
}

// Close closes all owned writers and returns a joined error, if any.
func (l *Logger) Close() error {
	var errs []error
	for _, writer := range l.writers {
		if writer == nil {
			continue
		}
		err := writer.Close()
		if err != nil {
			errs = append(errs, err)
		}
	}
	l.writers = nil
	return errors.Join(errs...)
}

// CreateTextWriter wraps an external writer with the logger text settings.
func (l *Logger) CreateTextWriter(w io.Writer) *LoggerTextWriter {
	return CreateTextWriter(w)
}

// CreateTextStdoutWriter creates a non-owning text writer for os.Stdout.
func (l *Logger) CreateTextStdoutWriter() *LoggerTextWriter {
	return CreateTextStdoutWriter()
}

// CreateTextFileWriter creates an owning text writer for a file.
func (l *Logger) CreateTextFileWriter(filename string) (*LoggerTextWriter, error) {
	return CreateTextFileWriter(filename)
}

// CreateJsonWriter wraps an external writer with the logger JSON settings.
func (l *Logger) CreateJsonWriter(w io.Writer) *LoggerJsonWriter {
	return CreateJsonWriter(w, l.jsonPretty)
}

// CreateJsonStdoutWriter creates a non-owning JSON writer for os.Stdout.
func (l *Logger) CreateJsonStdoutWriter() *LoggerJsonWriter {
	return CreateJsonStdoutWriter(l.jsonPretty)
}

// CreateJsonFileWriter creates an owning JSON writer for a file.
func (l *Logger) CreateJsonFileWriter(filename string) (*LoggerJsonWriter, error) {
	return CreateJsonFileWriter(filename, l.jsonPretty)
}

func (l *Logger) replace(s string) string {
	out := s
	for _, repl := range l.replacers {
		out = repl.replace(out)
	}
	return out
}

func (l *Logger) replaceAll(messages ...any) []any {
	if len(l.replacers) == 0 {
		return messages
	}
	out := make([]any, len(messages))
	for i, msg := range messages {
		out[i] = l.replace(fmt.Sprint(msg))
	}
	return out
}