package i18n

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

// R-603: html/template escapes ' " & < > in DATA. A bundle value that Go code renders into a page as
// data (a flash, a note, an error) therefore never appears verbatim on the page: "The system backup's
// drive…" arrives as "backup&#39;s", and a strings.Contains assertion for it fails exactly like a
// missing sentence — which sends the next person to re-fix a handler that was never broken. (Template
// copy is expanded textually by Expand and is NOT escaped; only Go-named values travel as data.)
//
// THE GATE: a Go-named value may not carry an HTML-escapable character unless it is registered below.
// The registered set is the measured state on 2026-10-05; a NEW value fails here with this pointer,
// so whoever writes it either rewords it or registers it AND asserts it with html.EscapeString(want).
var r603Registered = map[string]bool{
	"alert.endpoint_drift": true, "kept.choice.title": true, "kept.choice.fresh.desc": true,
	"err.backup.unit_version_mismatch": true, "note.tier2.unit_preserved": true,
	"err.stacks.setup_gate_failed": true, "err.kept.occupied": true, "update.refusal.no_backup": true,
	"update.error.journal_failed": true, "note.unit_restore_settings_only": true,
	"note.tier2_no_coverage": true, "note.tier2_unit_available": true, "note.tier2_unit_not_covered": true,
	"note.tier2_unit_confirm_base": true, "note.tier2_unit_stale_clause": true,
	"note.tier2_unit_stale_notice_fmt": true, "note.restore.whole_files": true,
	"note.restore.scratch_state": true,
}

var r603Escapable = regexp.MustCompile(`['"&<>]`)
var r603KeyShape = regexp.MustCompile(`^[a-z][a-z0-9_]*(?:\.[a-z0-9_\-]+)+$`)

// goNamedKeys returns every bundle key that appears as a string literal in non-test Go source under
// the given roots — the same "named in Go" rule scripts/i18n_go_parity.py applies.
func goNamedKeys(t *testing.T, bundle map[string]string, roots ...string) map[string]string {
	t.Helper()
	out := map[string]string{}
	fset := token.NewFileSet()
	for _, root := range roots {
		err := filepath.Walk(root, func(p string, info os.FileInfo, err error) error {
			if err != nil || info.IsDir() || !strings.HasSuffix(p, ".go") || strings.HasSuffix(p, "_test.go") {
				return err
			}
			f, perr := parser.ParseFile(fset, p, nil, 0)
			if perr != nil {
				return perr
			}
			ast.Inspect(f, func(n ast.Node) bool {
				if lit, ok := n.(*ast.BasicLit); ok && lit.Kind == token.STRING {
					if v, uerr := strconv.Unquote(lit.Value); uerr == nil && r603KeyShape.MatchString(v) {
						if _, ok := bundle[v]; ok {
							out[v] = p
						}
					}
				}
				return true
			})
			return nil
		})
		if err != nil {
			t.Fatal(err)
		}
	}
	return out
}

func r603Load(t *testing.T, lang string) map[string]string {
	t.Helper()
	raw, err := os.ReadFile(filepath.Join("locales", lang+".json"))
	if err != nil {
		t.Fatal(err)
	}
	var generic map[string]interface{}
	if err := json.Unmarshal(raw, &generic); err != nil {
		t.Fatal(err)
	}
	out := map[string]string{}
	for k, v := range generic {
		if s, ok := v.(string); ok {
			out[k] = s
		}
	}
	return out
}

// r603Offenders is the gate's verdict for one bundle: Go-named values carrying an escapable character
// that are not registered.
func r603Offenders(bundle, named map[string]string) []string {
	var bad []string
	for k := range named {
		if r603Escapable.MatchString(bundle[k]) && !r603Registered[k] {
			bad = append(bad, k)
		}
	}
	sort.Strings(bad)
	return bad
}

func TestR603_GoNamedValuesDoNotHideBehindHTMLEscaping(t *testing.T) {
	hu, en := r603Load(t, "hu"), r603Load(t, "en")
	named := goNamedKeys(t, hu, filepath.Join("..", "..", "internal"), filepath.Join("..", "..", "cmd"))
	if len(named) < 100 {
		t.Fatalf("control: only %d Go-named keys found — the source walk is not reaching the code", len(named))
	}
	// Decoy: a planted apostrophe in a Go-named value that is not registered must be caught.
	var some string
	for k := range named {
		if !r603Registered[k] {
			some = k
			break
		}
	}
	planted := map[string]string{}
	for k, v := range en {
		planted[k] = v
	}
	planted[some] = "The drive's copy"
	if got := r603Offenders(planted, named); len(got) != 1 || got[0] != some {
		t.Fatalf("control: a planted apostrophe in %s was not caught (got %v)", some, got)
	}

	for lang, b := range map[string]map[string]string{"hu": hu, "en": en} {
		for _, k := range r603Offenders(b, named) {
			t.Errorf("R-603 [%s] %s = %q (named in %s) carries a character html/template escapes in data "+
				"(' \" & < >): on the page it is not these bytes, and a strings.Contains assertion for it fails "+
				"like a missing sentence. Reword it (a typographic ’ is not escaped), or register it in "+
				"r603Registered and assert it with html.EscapeString(want).", lang, k, b[k], named[k])
		}
	}
	// A registration that no longer needs to be there is reported, so the list only shrinks.
	for k := range r603Registered {
		if _, ok := named[k]; !ok || !r603Escapable.MatchString(en[k]+hu[k]) {
			t.Errorf("R-603: %s is registered but no longer a Go-named value with an escapable character — remove it", k)
		}
	}
}