package usecase

import (
	"encoding/json"
	"strings"
	"testing"
	"unicode/utf8"
)

func TestBoundedDiagnosticJSON(t *testing.T) {
	for _, input := range []string{"", "plain", "<&>\n\"", "雪☃", "a\xff\xfe\xffb", "\xff\xfe" + strings.Repeat("z", 100)} {
		for budget := 0; budget <= 30; budget++ {
			encoded, complete := boundedDiagnosticJSON(input, budget)
			if budget < 2 {
				if encoded != nil || complete {
					t.Fatalf("budget %d: %q %v", budget, encoded, complete)
				}
				continue
			}
			if len(encoded) > budget || !utf8.Valid(encoded) {
				t.Fatalf("budget %d: %q", budget, encoded)
			}
			var decoded string
			if err := json.Unmarshal(encoded, &decoded); err != nil {
				t.Fatal(err)
			}
			normalized := strings.ToValidUTF8(input, "\uFFFD")
			if !strings.HasPrefix(normalized, decoded) || complete != (decoded == normalized) {
				t.Fatalf("input %q budget %d: %q complete=%v normalized=%q", input, budget, decoded, complete, normalized)
			}
		}
	}
}