package main

import (
	"path"
	"path/filepath"
)

var TgtCache = make(map[string]*Tgt)

func mustAbs(pth string) string {
	pth, err := filepath.Abs(pth)
	if err != nil {
		panic(err)
	}
	return pth
}

func mustRel(basepath, targpath string) string {
	pth, err := filepath.Rel(basepath, targpath)
	if err != nil {
		panic(err)
	}
	return pth
}

func cwdMustRel(paths ...string) string {
	return mustRel(Cwd, path.Join(paths...))
}

func pathSplit(a string) (h, t string) {
	h, t = path.Split(a)
	if len(h) > 1 {
		h = h[:len(h)-1]
	}
	return
}

type Tgt struct {
	a   string // absolute path
	rel string // relative to Cwd
	dep string // path to dependency file
}

func NewTgt(tgt string) *Tgt {
	a := mustAbs(tgt)
	if TgtCache != nil {
		if t := TgtCache[a]; t != nil {
			return t
		}
	}
	h, t := pathSplit(a)
	res := Tgt{
		a:   a,
		rel: mustRel(Cwd, a),
		dep: path.Join(h, RedoDir, t+DepSuffix),
	}
	if TgtCache != nil {
		TgtCache[a] = &res
	}
	return &res
}

func (tgt *Tgt) String() string {
	return tgt.rel
}

func (tgt *Tgt) RelTo(cwd string) string {
	return mustRel(cwd, tgt.a)
}