package codec_test

import (
	"encoding/hex"
	"encoding/json"
	"math"
	"os"
	"strconv"
	"testing"

	datekeys "g.activething.com/go/DateKeys"
	"g.activething.com/go/DateKeys/codec"
)

// cborVectors is the generic part of testdata/vectors/cbor.json, which
// internal/testkit.CBORVectors generates.
type cborVectors struct {
	Walk struct {
		MaxDepth int `json:"max_depth"`
		MaxLen   int `json:"max_len"`
	} `json:"walk"`
	Accept []struct {
		Name  string          `json:"name"`
		Hex   string          `json:"hex"`
		Value json.RawMessage `json:"value"`
	} `json:"accept"`
	Reject []struct {
		Name  string `json:"name"`
		Hex   string `json:"hex"`
		Error string `json:"error"`
	} `json:"reject"`
}

// The shared vectors of the CBOR profile (spec §58): Walk accepts exactly the
// accept list, with the value recorded for unsigned integers (a decimal string
// above 2^53-1), and rejects the reject list with the recorded code.
func TestSharedVectors(t *testing.T) {
	b, err := os.ReadFile("../testdata/vectors/cbor.json")
	if err != nil {
		t.Fatal(err)
	}
	var f cborVectors
	if err := json.Unmarshal(b, &f); err != nil {
		t.Fatal(err)
	}
	if len(f.Accept) == 0 || len(f.Reject) == 0 || f.Walk.MaxDepth == 0 || f.Walk.MaxLen == 0 {
		t.Fatal("incomplete vector file")
	}
	for _, v := range f.Accept {
		in, err := hex.DecodeString(v.Hex)
		if err != nil {
			t.Fatal(err)
		}
		if err := codec.Walk(in, f.Walk.MaxDepth, f.Walk.MaxLen); err != nil {
			t.Errorf("%s: %v", v.Name, err)
			continue
		}
		if v.Value == nil {
			continue
		}
		n, err := codec.NewDecoder(in).Uint(math.MaxUint64)
		if err != nil {
			t.Fatalf("%s: %v", v.Name, err)
		}
		want := strconv.FormatUint(n, 10)
		if n > codec.MaxSafeUint {
			want = strconv.Quote(want)
		}
		if string(v.Value) != want {
			t.Errorf("%s: value %s, want %s", v.Name, v.Value, want)
		}
	}
	for _, v := range f.Reject {
		in, err := hex.DecodeString(v.Hex)
		if err != nil {
			t.Fatal(err)
		}
		if got := datekeys.Code(codec.Walk(in, f.Walk.MaxDepth, f.Walk.MaxLen)); got != v.Error {
			t.Errorf("%s: got %q, want %s", v.Name, got, v.Error)
		}
	}
}