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...))
}

type Tgt struct {
	// a/h/t resemble zsh'es :a, :h, :t modifiers
	a   string // absolute path
	h   string // head of the path, directory
	t   string // tail of the path, only name
	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
		}
	}
	t := Tgt{a: a}
	t.h, t.t = path.Split(t.a)
	if len(t.h) > 1 {
		t.h = t.h[:len(t.h)-1]
	}
	t.rel = mustRel(Cwd, t.a)
	if TgtCache != nil {
		TgtCache[a] = &t
	}
	return &t
}

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

func (tgt *Tgt) Dep() string {
	if tgt.dep == "" {
		tgt.dep = path.Join(tgt.h, RedoDir, tgt.t+DepSuffix)
	}
	return tgt.dep
}

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