package stdlibx

import (
	"errors"
	"strings"
)

type LevelMapper func(text string, fallbackLevel int) int

type Options struct {
	Prefix      string
	Flags       int
	ShowStd     bool
	TrimNewline bool
	LevelMapper LevelMapper
}

type Option func(*Options)

func DefaultOptions() Options {
	return Options{
		Prefix:      "",
		Flags:       0,
		ShowStd:     false,
		TrimNewline: true,
		LevelMapper: nil,
	}
}

func WithPrefix(prefix string) Option {
	return func(options *Options) {
		if options == nil {
			return
		}
		options.Prefix = prefix
	}
}

func WithFlags(flags int) Option {
	return func(options *Options) {
		if options == nil {
			return
		}
		options.Flags = flags
	}
}

func WithShowStd(show bool) Option {
	return func(options *Options) {
		if options == nil {
			return
		}
		options.ShowStd = show
	}
}

func WithTrimNewline(trim bool) Option {
	return func(options *Options) {
		if options == nil {
			return
		}
		options.TrimNewline = trim
	}
}

func WithLevelMapper(mapper LevelMapper) Option {
	return func(options *Options) {
		if options == nil {
			return
		}
		options.LevelMapper = mapper
	}
}

func NormalizeOptions(opts []Option) Options {
	options := DefaultOptions()
	for _, option := range opts {
		if option == nil {
			continue
		}
		option(&options)
	}
	return options
}

type EmitFunc func(level int, showStd bool, text string)

type Writer struct {
	level       int
	showStd     bool
	trimNewline bool
	levelMapper LevelMapper
	emit        EmitFunc
}

func NewWriter(level int, options Options, emit EmitFunc) *Writer {
	return &Writer{
		level:       level,
		showStd:     options.ShowStd,
		trimNewline: options.TrimNewline,
		levelMapper: options.LevelMapper,
		emit:        emit,
	}
}

func (writer *Writer) SetShowStd(show bool) {
	if writer == nil {
		return
	}
	writer.showStd = show
}

func (writer *Writer) SetTrimNewline(trim bool) {
	if writer == nil {
		return
	}
	writer.trimNewline = trim
}

func (writer *Writer) Write(data []byte) (int, error) {
	if writer == nil || writer.emit == nil {
		return 0, errors.New("level writer logger is nil")
	}
	text := string(data)
	if writer.trimNewline {
		text = strings.TrimRight(text, "\r\n")
	}
	if text != "" {
		level := writer.level
		if writer.levelMapper != nil {
			level = writer.levelMapper(text, level)
		}
		writer.emit(level, writer.showStd, text)
	}
	return len(data), nil
}