// Command readable refuses a catalogue where a module reads another module's state that the owner does not announce
// readable (novox/hq ADR 0495 clause 3, issue 1790): the controller grants a read only from the owner's announcement, so
// such a read is refused on the live mesh, said only in the controller's journal. The sweep of 2026-10-30 (issue 774)
// found three: gitea's `bound` (read by mesh-provisioner, so no forge account was bound), disk-load's `readings` (read by
// restic, nfs-server and mounts) and restic's `good` (read by the self-check). The merge gate's check of reads against
// the owner's manifest went with clause 5, and announcetest holds a module to its own list, not to its readers.
//
// An owner announces from its code. A Go module announces when its code imports mesh-sdk's go/announce: every
// announce.State literal there is read, its Name a string, a constant of the package, or a constant of mesh-sdk this
// check knows (Known). A TypeScript module announces when its code says the event `states` or calls the SDK's keeps:
// every `{ name: "...", readable: true }` there is read. An owner that announces nothing from code is read as before
// on the mesh, and is not judged; neither is an owner outside the catalogue (another repository's).
//
//	go run . <catalog root>
//
// Exits 1 on a finding.
package main

import (
	"encoding/json"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"

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

// Known are the mesh-sdk constants an announcement may name a state by, by the selector the code writes.
var Known = map[string]string{
	"health.GoodState":     health.GoodState,
	"health.ReadingsState": health.ReadingsState,
}

const announcePkg = `"git.novox.be/novox/mesh-sdk/go/announce"`

// Announced is what one owner's code announces: each state, readable or not.
type Announced map[string]bool

// Findings is every refusal in the catalogue at root, sorted.
func Findings(root string) ([]string, error) {
	manifests, err := filepath.Glob(filepath.Join(root, "modules", "*", "module.json"))
	if err != nil {
		return nil, err
	}
	dirs := map[string]string{}
	reads := map[string][]string{}
	for _, path := range manifests {
		raw, err := os.ReadFile(path)
		if err != nil {
			return nil, err
		}
		var m struct {
			Module string            `json:"module"`
			Reads  []json.RawMessage `json:"reads"`
		}
		if err := json.Unmarshal(raw, &m); err != nil {
			return nil, fmt.Errorf("%s: %w", path, err)
		}
		dirs[m.Module] = filepath.Dir(path)
		for _, r := range m.Reads {
			var s string
			if json.Unmarshal(r, &s) == nil {
				reads[m.Module] = append(reads[m.Module], s)
			}
		}
	}
	var out []string
	owners := map[string]Announced{}
	for reader, rs := range reads {
		for _, r := range rs {
			owner, state, ok := strings.Cut(r, ".")
			dir, inCatalogue := dirs[owner]
			if !ok || !inCatalogue || owner == reader {
				continue
			}
			a, seen := owners[owner]
			if !seen {
				var problems []string
				a, problems, err = AnnouncedBy(dir)
				if err != nil {
					return nil, err
				}
				owners[owner] = a
				for _, p := range problems {
					out = append(out, owner+": "+p)
				}
			}
			if a == nil {
				continue // announces nothing from code: read as before
			}
			readable, keeps := a[state]
			switch {
			case !keeps:
				out = append(out, fmt.Sprintf("%s reads %s.%s, which %s's code does not announce: the read is refused on the mesh", reader, owner, state, owner))
			case !readable:
				out = append(out, fmt.Sprintf("%s reads %s.%s, which %s's code announces not readable: the read is refused on the mesh; announce it readable", reader, owner, state, owner))
			}
		}
	}
	sort.Strings(out)
	return dedupe(out), nil
}

func dedupe(in []string) []string {
	var out []string
	for i, s := range in {
		if i == 0 || s != in[i-1] {
			out = append(out, s)
		}
	}
	return out
}

var (
	tsAnnounces = regexp.MustCompile(`emit\(\s*"states"|\bkeeps\(`)
	tsState     = regexp.MustCompile(`\{\s*name:\s*"([a-z0-9][a-z0-9-]*)"\s*(,\s*readable:\s*(true|false)\s*)?\}`)
)

// AnnouncedBy is what the module in dir announces from its code, nil when it announces nothing; problems are
// announcements whose state's name cannot be read.
func AnnouncedBy(dir string) (Announced, []string, error) {
	var out Announced
	var problems []string
	pkgs := map[string][]*ast.File{}
	fset := token.NewFileSet()
	err := filepath.WalkDir(dir, func(path string, d os.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			if n := d.Name(); path != dir && (n == "node_modules" || n == "dist" || n == "test" || n == "testdata" || strings.HasPrefix(n, ".")) {
				return filepath.SkipDir
			}
			return nil
		}
		name := d.Name()
		switch {
		case strings.HasSuffix(name, ".go") && !strings.HasSuffix(name, "_test.go"):
			f, err := parser.ParseFile(fset, path, nil, 0)
			if err != nil {
				return err
			}
			pkgs[filepath.Dir(path)] = append(pkgs[filepath.Dir(path)], f)
		case strings.HasSuffix(name, ".ts") && !strings.HasSuffix(name, ".d.ts") && !strings.HasSuffix(name, ".test.ts"):
			raw, err := os.ReadFile(path)
			if err != nil {
				return err
			}
			if !tsAnnounces.Match(raw) && !strings.Contains(string(raw), "KEPT") {
				return nil
			}
			for _, m := range tsState.FindAllStringSubmatch(string(raw), -1) {
				if out == nil {
					out = Announced{}
				}
				out[m[1]] = out[m[1]] || m[3] == "true"
			}
		}
		return nil
	})
	if err != nil {
		return nil, nil, err
	}
	for _, files := range pkgs {
		imports := false
		consts := map[string]ast.Expr{}
		for _, f := range files {
			for _, im := range f.Imports {
				if im.Path.Value == announcePkg && (im.Name == nil || im.Name.Name == "announce") {
					imports = true
				}
			}
			for _, decl := range f.Decls {
				g, ok := decl.(*ast.GenDecl)
				if !ok || g.Tok != token.CONST {
					continue
				}
				for _, spec := range g.Specs {
					v := spec.(*ast.ValueSpec)
					for i, n := range v.Names {
						if i < len(v.Values) {
							consts[n.Name] = v.Values[i]
						}
					}
				}
			}
		}
		if !imports {
			continue
		}
		if out == nil {
			out = Announced{}
		}
		for _, f := range files {
			ast.Inspect(f, func(n ast.Node) bool {
				lit, ok := n.(*ast.CompositeLit)
				if !ok {
					return true
				}
				states := []*ast.CompositeLit{}
				switch {
				case isAnnounceState(lit.Type):
					states = append(states, lit)
				case isStateSlice(lit.Type):
					for _, e := range lit.Elts {
						if c, ok := e.(*ast.CompositeLit); ok && (c.Type == nil || isAnnounceState(c.Type)) {
							states = append(states, c)
						}
					}
				default:
					return true
				}
				for _, s := range states {
					name, readable, problem := stateOf(s, consts)
					if problem != "" {
						problems = append(problems, fmt.Sprintf("%s: %s", fset.Position(s.Pos()), problem))
						continue
					}
					out[name] = out[name] || readable
				}
				return false
			})
		}
	}
	return out, problems, nil
}

func isAnnounceState(e ast.Expr) bool {
	s, ok := e.(*ast.SelectorExpr)
	if !ok {
		return false
	}
	x, ok := s.X.(*ast.Ident)
	return ok && x.Name == "announce" && s.Sel.Name == "State"
}

func isStateSlice(e ast.Expr) bool {
	a, ok := e.(*ast.ArrayType)
	return ok && isAnnounceState(a.Elt)
}

// stateOf is one announce.State literal's name and whether it is readable (Readable true, or Readers named).
func stateOf(lit *ast.CompositeLit, consts map[string]ast.Expr) (string, bool, string) {
	var name string
	var readable bool
	named := false
	for _, e := range lit.Elts {
		kv, ok := e.(*ast.KeyValueExpr)
		if !ok {
			return "", false, "an announce.State without field names cannot be read; name its fields"
		}
		key, _ := kv.Key.(*ast.Ident)
		if key == nil {
			continue
		}
		switch key.Name {
		case "Name":
			v, ok := resolve(kv.Value, consts, 0)
			if !ok {
				return "", false, fmt.Sprintf("the state's name %s cannot be read: name it by a string, a constant of the package, or a mesh-sdk constant in checks/readable's Known", exprString(kv.Value))
			}
			name, named = v, true
		case "Readable":
			if id, ok := kv.Value.(*ast.Ident); ok {
				readable = readable || id.Name == "true"
			}
		case "Readers":
			readable = true
		}
	}
	if !named {
		return "", false, "an announce.State without a Name"
	}
	return name, readable, ""
}

func resolve(e ast.Expr, consts map[string]ast.Expr, depth int) (string, bool) {
	if depth > 8 {
		return "", false
	}
	switch v := e.(type) {
	case *ast.BasicLit:
		if v.Kind == token.STRING {
			s, err := strconv.Unquote(v.Value)
			return s, err == nil
		}
	case *ast.Ident:
		if c, ok := consts[v.Name]; ok {
			return resolve(c, consts, depth+1)
		}
	case *ast.SelectorExpr:
		s, ok := Known[exprString(v)]
		return s, ok
	}
	return "", false
}

func exprString(e ast.Expr) string {
	switch v := e.(type) {
	case *ast.Ident:
		return v.Name
	case *ast.SelectorExpr:
		return exprString(v.X) + "." + v.Sel.Name
	case *ast.BasicLit:
		return v.Value
	}
	return fmt.Sprintf("%T", e)
}

func main() {
	root := "."
	if len(os.Args) > 1 {
		root = os.Args[1]
	}
	found, err := Findings(root)
	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)
	}
}