// Command placement is the catalogue's check of its placement files (novox/hq ADR 0549 §1, ADR 0555; issue 1126): every
// `placement/<node>.json` reads as a placement of the node its name says, and the files together are refused, every
// finding named at once, for two modules of one node on one host port, a pin, binding or holding naming a provider not
// placed where it says, a seat held once for the mesh held twice, two nodes with one address on the private network, or
// more than one hub (mesh-sdk delivery.CheckPlacements).
//
// A module the catalogue does not hold and a node not enrolled are the composition check's to refuse: placement names
// modules of every repository the indexer reads and the nodes the mesh enrolled, neither of which this tree holds.
//
//	go run . <catalogue root>
//
// Exits 1 on a finding.
package main

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"

	"git.novox.be/novox/mesh-sdk/go/delivery"
)

// Check reads every placement file under root and answers each finding; none is a catalogue whose placement holds. A
// catalogue with no placement directory has none to check.
func Check(root string) ([]string, error) {
	dir := filepath.Join(root, delivery.PlacementDir)
	entries, err := os.ReadDir(dir)
	if os.IsNotExist(err) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	var found []string
	placements := map[string]delivery.Placement{}
	for _, e := range entries {
		rel := delivery.PlacementDir + "/" + e.Name()
		node, ok := delivery.PlacementFileNode(rel)
		if e.IsDir() || !ok {
			found = append(found, fmt.Sprintf("%s is not a placement file: the directory holds only <node>.json, one per node", rel))
			continue
		}
		raw, err := os.ReadFile(filepath.Join(dir, e.Name()))
		if err != nil {
			return nil, err
		}
		p, err := delivery.DecodePlacement(raw)
		if err != nil {
			found = append(found, fmt.Sprintf("%s does not read as a placement: %v", rel, err))
			continue
		}
		if p.Revision != "" {
			found = append(found, fmt.Sprintf("%s names a revision, which only the indexer writes into the key", rel))
		}
		placements[node] = p
	}
	all := func(string) bool { return true }
	found = append(found, delivery.CheckPlacements(placements, all, all)...)
	sort.Strings(found)
	return found, nil
}

func main() {
	if len(os.Args) != 2 {
		fmt.Fprintln(os.Stderr, "usage: placement <catalogue root>")
		os.Exit(2)
	}
	found, err := Check(os.Args[1])
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(2)
	}
	for _, f := range found {
		fmt.Println(f)
	}
	if len(found) > 0 {
		os.Exit(1)
	}
}