package main

import (
	_ "embed"
	"encoding/json"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"text/template"
)

//go:embed "templates/deps.dot.tmpl"
var tpl string

// ComposerName is the reserved name of the Composer specifications file.
const ComposerName = "composer.json"

/*
In most cases: <owner>/<project>, but some special cases are valid too, like
"php", "ext-<extension>", "lib-<library>"
*/
type projectID string
type semverClause string

type node struct {
	ID    projectID
	Path  string
	Links map[projectID]semverClause
}

type composer struct {
	ID         projectID `json:"name"`
	Require    map[projectID]semverClause
	RequireDev map[projectID]semverClause
}

func (n *node) SetRequire(reqs map[projectID]semverClause) {
	// todo Probably use a positive list instead of a negative list
	parts := []string{
		`api-platform/`,
		`aporat/`,
		`babdev/`,
		`cocur/`,
		`composer/`,
		`doctrine/`,
		`eo/`,
		`ergebnis/`,
		`evence/`,
		`ext-`,
		`firebase/`,
		`flow/`,
		`friendsofphp/`,
		`friendsofsymfony/`,
		`google/`,
		`guzzlehttp/`,
		`http-interop/`,
		`hwi/`,
		`incenteev/`,
		`kelvinmo/`,
		`knpuniversity/`,
		`league/`,
		`liip/`,
		`myclabs/`,
		`nelmio/`,
		`nesbot/`,
		`oneup/`,
		`php$`,
		`php-amqplib/`,
		`php-http/`,
		`php-parallel-lint/`,
		`phpdocumentor/`,
		`phpro/`,
		`phpseclib/`,
		`phpstan/`,
		`psr/`,
		`pyrech/`,
		`ramsey/`,
		`rector/`,
		`sensio/`,
		`sensiolabs/`,
		`snc/`,
		`spatie/`,
		`stof/`,
		`symfony/`,
		`tgalopin/`,
		`thecodingmachine/`,
		`twig/`,
		`vich/`,
		`wearejust/`,
		`white-october/`,
		`wikimedia/`,
		`yokai/`,
	}
	excluded, err := regexp.Compile(`^(` + strings.Join(parts, `|`) + `)`)
	// Regex is a literal, so it should never happen.
	if err != nil {
		panic(err)
	}
	for id, ver := range reqs {
		if excluded.MatchString(string(id)) {
			continue
		}
		n.Links[id] = ver
	}
}

func scanComposer(dir string, nodes map[string]node, path string) error {
	f, err := os.Open(path)
	if err != nil {
		return err
	}
	dec := json.NewDecoder(f)
	c := composer{}
	if err := dec.Decode(&c); err != nil {
		return err
	}
	shortPath := path[len(dir)+1 : len(path)-len(ComposerName)-1]
	if c.ID == "" {
		c.ID = projectID(strings.Join([]string{"__magic", shortPath}, "/"))
	}
	n := node{
		ID:    c.ID,
		Path:  shortPath,
		Links: map[projectID]semverClause{},
	}
	n.SetRequire(c.Require)
	nodes[shortPath] = n
	return nil
}

func walk(nodes map[string]node, dir string) error {
	return filepath.WalkDir(dir, func() fs.WalkDirFunc {
		return func(path string, d fs.DirEntry, err error) error {
			if err != nil {
				return err
			}
			name := d.Name()
			if name != ComposerName {
				return nil
			}
			return scanComposer(dir, nodes, path)
		}
	}())
}

func main() {
	nodes := make(map[string]node)
	if len(os.Args) != 2 {
		log.Fatalf("Usage: %s <root dir>", os.Args[0])
	}
	dirName := os.Args[1]
	stat, err := os.Stat(dirName)
	if err != nil {
		log.Fatalf("Cannot read %s: %v", dirName, err)
	}
	if !stat.IsDir() {
		log.Fatalf("%s is not a directory", dirName)
	}
	err = walk(nodes, dirName)
	if err != nil {
		log.Fatalf("Walking %s: %v", dirName, err)
	}
	tpl, err := template.New("dot").Parse(tpl)
	if err != nil {
		log.Fatalf("Parsing template: %v", err)
	}
	_ = tpl.Execute(os.Stdout, nodes)
}