package logger

import (
	"encoding/json"
	"fmt"
	"io"
	"strings"
	"time"
)

type Formatter interface {
	Format(writer io.Writer, entry *Entry)
}

type textFormatter struct {
	timeFormat string
	prefix     string
}

type jsonFormatter struct{}

func newFormatter(format Format) Formatter {
	switch format {
	case JSON:
		return &jsonFormatter{}
	default:
		return &textFormatter{
			timeFormat: "2006-01-02 15:04:05",
		}
	}
}

func (f *textFormatter) Format(writer io.Writer, entry *Entry) {
	parts := make([]string, 0, 8)
	parts = append(parts, entry.Time.Format(f.timeFormat))
	parts = append(parts, entry.Level.String())

	if f.prefix != "" {
		parts = append(parts, "["+f.prefix+"]")
	}

	if entry.Caller != "" {
		parts = append(parts, entry.Caller)
	}

	parts = append(parts, entry.Message)

	if len(entry.Fields) > 0 {
		fieldStrs := make([]string, 0, len(entry.Fields))
		for k, v := range entry.Fields {
			fieldStrs = append(fieldStrs, fmt.Sprintf("%s=%v", k, v))
		}
		parts = append(parts, strings.Join(fieldStrs, " "))
	}

	fmt.Fprintln(writer, strings.Join(parts, " "))
}

func (f *jsonFormatter) Format(writer io.Writer, entry *Entry) {
	m := map[string]interface{}{
		"time":    entry.Time.Format(time.RFC3339),
		"level":   entry.Level.String(),
		"message": entry.Message,
	}

	if entry.Caller != "" {
		m["caller"] = entry.Caller
	}

	for k, v := range entry.Fields {
		m[k] = v
	}

	data, _ := json.Marshal(m)
	writer.Write(data)
	writer.Write([]byte("\n"))
}