package log

import (
	"fmt"
	"git.giftfish.de/ston1th/docstore/pkg/core"
	"strings"
	"sync"
)

const defaultSize = 500

type ScanLog struct {
	// protects logs
	sync.RWMutex

	size int
	logs []string
}

func NewScanLog(size int) *ScanLog {
	if size <= 0 {
		size = defaultSize
	}
	return &ScanLog{size: size}
}

func (l *ScanLog) Printf(f string, v ...interface{}) {
	s := fmt.Sprintf(f, v...)
	Println(s)
	s = core.LogTime() + s
	l.Lock()
	llen := len(l.logs)
	if llen < l.size {
		l.logs = append(l.logs, s)
	} else if llen == l.size {
		l.logs = append(l.logs[1:], s)
	}
	l.Unlock()
}

func (l *ScanLog) Logs() (logs string) {
	l.RLock()
	logs = reverseJoin(l.logs, "\n")
	l.RUnlock()
	return
}

// reverseJoin is a reverse version of strings.Join
// code taken from strings.Join
func reverseJoin(a []string, sep string) string {
	switch len(a) {
	case 0:
		return ""
	case 1:
		return a[0]
	}
	n := len(sep) * (len(a) - 1)
	for i := 0; i < len(a); i++ {
		n += len(a[i])
	}

	var b strings.Builder
	b.Grow(n)
	b.WriteString(a[len(a)-1])
	for i := len(a) - 2; i >= 0; i-- {
		b.WriteString(sep)
		b.WriteString(a[i])
	}
	return b.String()
}