/*
goredo -- djb's redo implementation on pure Go
Copyright (C) 2020-2023 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package main

import (
	"os"
	"path"
)

func sourcesWalker(
	tgts []string,
	seen map[string]struct{},
	seenDeps map[string]struct{},
	srcs map[string]struct{},
) error {
	for _, tgt := range tgts {
		tgtAbsPath := mustAbs(path.Join(Cwd, tgt))
		cwd, f := path.Split(path.Join(Cwd, tgt))
		depPath := path.Join(cwd, RedoDir, f+DepSuffix)
		if _, ok := seenDeps[depPath]; ok {
			continue
		}
		seenDeps[depPath] = struct{}{}
		fdDep, err := os.Open(depPath)
		if err != nil {
			if errors.Is(err, fs.ErrNotExist) {
				continue
			}
			return ErrLine(err)
		}
		depInfo, err := depRead(fdDep)
		fdDep.Close()
		if err != nil {
			return ErrLine(err)
		}
		for _, m := range depInfo.ifchanges {
			depTgt := m["Target"]
			depTgtAbsPath := mustAbs(path.Join(cwd, depTgt))
			if _, ok := seen[depTgtAbsPath]; ok {
				continue
			}
			seen[depTgtAbsPath] = struct{}{}
			if isSrc(cwd, depTgt) {
				srcs[cwdMustRel(depTgtAbsPath)] = struct{}{}
			} else if depTgtAbsPath != tgtAbsPath {
				if err := sourcesWalker(
					[]string{cwdMustRel(depTgtAbsPath)},
					seen, seenDeps, srcs,
				); err != nil {
					return err
				}
			}
		}
	}
	return nil
}