/*
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/>.
*/

// Dependency DOT graph generation

package main

import (
	"errors"
	"fmt"
	"io"
	"os"
	"path"

	"go.cypherpunks.ru/recfile"
)

type DotNodes struct {
	from string
	to   string
}

func dotWalker(data map[DotNodes]bool, tgt *Tgt) (map[DotNodes]bool, error) {
	fdDep, err := os.Open(tgt.Dep())
	if err != nil {
		return nil, ErrLine(err)
	}
	defer fdDep.Close()
	var dep *Tgt
	r := recfile.NewReader(fdDep)
	for {
		m, err := r.NextMap()
		if err != nil {
			if errors.Is(err, io.EOF) {
				break
			}
			return nil, ErrLine(err)
		}
		switch m["Type"] {
		case DepTypeIfcreate:
			data[DotNodes{tgt.String(), NewTgt(m["Target"]).String()}] = true
		case DepTypeIfchange:
			dep = NewTgt(path.Join(tgt.h, m["Target"]))
			if dep.a == tgt.a {
				continue
			}
			data[DotNodes{tgt.String(), dep.String()}] = false
			if isSrc(dep) {
				continue
			}
			data, err = dotWalker(data, dep)
			if err != nil {
				return nil, err
			}
		}
	}
	return data, nil
}

func dotPrint(tgts []*Tgt) error {
	data := map[DotNodes]bool{}
	var err error
	for _, tgt := range tgts {
		data, err = dotWalker(data, tgt)
		if err != nil {
			return err
		}
	}
	fmt.Println(`digraph d {
	rankdir=LR
	ranksep=2
	splines=false // splines=ortho
	node[shape=rectangle]`)
	for nodes, nonexistent := range data {
		fmt.Printf("\n\t\"%s\" -> \"%s\"", nodes.from, nodes.to)
		if nonexistent {
			fmt.Print(" [style=dotted]")
		}
	}
	fmt.Println("\n}")
	return nil
}