package lerror

import (
	"fmt"
	"os"
	"path/filepath"
	"runtime"
)

var (
	lenBasePath int = 0
)

func init() {
	path, err := os.Executable()
	if err != nil {
		path = ""
	}
	lenBasePath = len(filepath.Dir(path))
}

type Error struct {
	msg   string
	trace []string
}

func NewString(msg string) *Error {
	return &Error{
		msg:   msg,
		trace: []string{trace()},
	}
}

func NewError(err error) *Error {
	return &Error{
		msg:   err.Error(),
		trace: []string{trace()},
	}
}

func (it *Error) Add(msg string) *Error {
	it.trace = append(it.trace, trace())
	it.msg = msg + ": " + it.msg
	return it
}

func (it *Error) String() string {
	result := it.msg
	for _, line := range it.trace {
		result += "\n" + line
	}
	return result
}

func trace() string {
	_, file, line, ok := runtime.Caller(2)
	if !ok {
		return "not possible to recover the information"
	}
	if lenBasePath < len(file) {
		return fmt.Sprintf("%s:%d", file[lenBasePath:], line)
	} else {
		return fmt.Sprintf("%s:%d", file, line)
	}
}