//go:build gofuzz

package tce

// Fuzz is the OSS-Fuzz entry point for the primitive TCE codec. It asserts two
// totality properties of PROTOCOL.md section 12.4 against arbitrary input:
//
//   - the decoder never panics, hangs or returns a usable object alongside an
//     error (totality); the decoder is walked field by field and each read
//     ignores its result;
//   - CanonicalNumber (section 5.1) is total over arbitrary text and only ever
//     produces an already-canonical token, so a malformed number is rejected
//     rather than silently accepted.
//
// The function is compiled only under the "gofuzz" build tag (go-fuzz /
// OSS-Fuzz). Under that tag the Go test files are excluded, so there is no
// clash with the testing.F-based fuzz targets in the package.
func Fuzz(data []byte) int {
	d := NewDecoder(data)
	_, _ = d.Header()
	_, _ = d.Uvarint()
	_, _ = d.String(1 << 20)
	_, _ = d.Map(0)
	_, _ = d.Timestamp(true)
	_, _ = d.Identity()

	// Signal interesting inputs that survive canonicalization, guiding the
	// fuzzer toward the number parser's branches.
	if c, err := CanonicalNumber(string(data)); err == nil && IsCanonicalNumber(c) {
		return 1
	}
	return 0
}