// Command noplacement refuses what the repository path of placement left behind (novox/hq ADR 0567 §10, §12).
//
// Placement, which module runs on which node, is bus state held by the seat mesh-placement; no file of the
// catalogue says it, and no manifest reads it from the delivery indexer, which no longer keeps it. It refuses:
//
//  1. a `placement` directory (or file) at the root of the catalogue;
//
//  2. a `particulars` file at the root (the mesh's node names come from the checker's run, §16);
//
//  3. a manifest naming a state, stream, event or bucket of the indexer's placement (`mesh-delivery-indexer.placement…`
//     or `mesh-delivery-indexer_placement…`) in any string value, such as `reads`.
//
//     go run . <catalogue root>
//
// Exits 1 on a finding.
package main

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// Prefixes are the names of the indexer's placement parts; a manifest string starting with one names them.
var Prefixes = []string{"mesh-delivery-indexer.placement", "mesh-delivery-indexer_placement"}

// Findings is every refusal in the catalogue at root, sorted.
func Findings(root string) ([]string, error) {
	var out []string
	if _, err := os.Lstat(filepath.Join(root, "placement")); err == nil {
		out = append(out, "placement: the repository holds no placement; it is bus state of the seat mesh-placement (novox/hq ADR 0567 §10)")
	}
	if _, err := os.Lstat(filepath.Join(root, "particulars")); err == nil {
		out = append(out, "particulars: the repository lists no node names; the checker hands them to the check (novox/hq ADR 0567 §16)")
	}
	manifests, err := filepath.Glob(filepath.Join(root, "modules", "*", "module.json"))
	if err != nil {
		return nil, err
	}
	sort.Strings(manifests)
	for _, file := range manifests {
		raw, err := os.ReadFile(file)
		if err != nil {
			return nil, err
		}
		var doc any
		if err := json.Unmarshal(raw, &doc); err != nil {
			return nil, fmt.Errorf("%s: %w", file, err)
		}
		module := filepath.Base(filepath.Dir(file))
		for _, s := range named(doc, nil) {
			out = append(out, fmt.Sprintf("%s: names %q, which the indexer no longer keeps; placement is the seat mesh-placement's (novox/hq ADR 0567 §12)", module, s))
		}
	}
	return out, nil
}

// named collects the strings of a decoded manifest that start with one of the Prefixes.
func named(v any, into []string) []string {
	switch v := v.(type) {
	case string:
		for _, p := range Prefixes {
			if strings.HasPrefix(v, p) {
				return append(into, v)
			}
		}
	case []any:
		for _, e := range v {
			into = named(e, into)
		}
	case map[string]any:
		for _, e := range v {
			into = named(e, into)
		}
	}
	return into
}

func main() {
	if len(os.Args) != 2 {
		fmt.Fprintln(os.Stderr, "usage: noplacement <catalogue root>")
		os.Exit(2)
	}
	found, err := Findings(os.Args[1])
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	for _, f := range found {
		fmt.Println(f)
	}
	if len(found) > 0 {
		os.Exit(1)
	}
	fmt.Println("no placement directory, and no manifest reads the indexer's placement")
}