package fserr

import (
	"fmt"
	"github.com/pkg/errors"
	"runtime"
)

// stack represents a stack of program counters.
type stack []uintptr

func (s *stack) Format(st fmt.State, verb rune) {
	switch verb {
	case 'v':
		switch {
		case st.Flag('+'):
			for _, pc := range *s {
				fmt.Fprintf(st, "\n%+v", errors.Frame(pc))
			}
		}
	}
}

func (s *stack) StackTrace() errors.StackTrace {
	f := make([]errors.Frame, len(*s))
	for i := 0; i < len(f); i++ {
		f[i] = errors.Frame((*s)[i])
	}
	return f
}

func callers() *stack {
	var pcs [32]uintptr
	var st stack = pcs[0:runtime.Callers(3, pcs[:])]
	return &st
}