package ident_test

import (
	"encoding"
	"encoding/base64"
	"fmt"
	"reflect"
	"testing"

	"git.gensokyo.uk/cofront/cof-spec/ident"
)

// rTestCases describes multiple representation test cases.
type rTestCases[V any, S interface {
	encoding.TextMarshaler
	encoding.TextUnmarshaler
	fmt.Stringer

	*V
}] []struct {
	name  string
	ident V
	want  []byte
	err   error
}

// checkRepresentation runs tests described by testCases.
func (testCases rTestCases[V, S]) run(t *testing.T) {
	t.Helper()

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			t.Helper()
			t.Parallel()

			t.Run("decode", func(t *testing.T) {
				t.Helper()
				t.Parallel()

				var got V
				if err := S(&got).UnmarshalText(tc.want); !reflect.DeepEqual(err, tc.err) {
					t.Fatalf("UnmarshalText: error = %v, want %v", err, tc.err)
				}

				if tc.err != nil {
					return
				}

				if !reflect.DeepEqual(got, tc.ident) {
					t.Errorf("UnmarshalText: %#v, want %#v", got, tc.ident)
				}
			})

			if tc.err != nil {
				return
			}

			t.Run("encode", func(t *testing.T) {
				t.Helper()
				t.Parallel()

				if got, err := S(&tc.ident).MarshalText(); err != nil {
					t.Fatalf("MarshalText: error = %v", err)
				} else if string(got) != string(tc.want) {
					raw, decodeErr := base64.URLEncoding.AppendDecode(nil, got)
					t.Logf("AppendDecode: %#v, error = %v", raw, decodeErr)

					t.Errorf("MarshalText: %#v, want %#v", got, tc.want)
				}

				if got := S(&tc.ident).String(); got != string(tc.want) {
					t.Errorf("String: %s, want %s", got, tc.want)
				}
			})
		})
	}
}

func TestErrors(t *testing.T) {
	t.Parallel()

	testCases := []struct {
		name string
		err  error
		want string
	}{
		{"UnexpectedSizeError", &ident.UnexpectedSizeError{
			Data: make([]byte, 1<<10),
			Want: ident.EncodedSizeSystem,
		}, "got 1024 bytes for a 32-byte identifier"},

		{"InvalidLabelLDH start", &ident.InvalidLabelError{
			Data:   []byte{'-'},
			Label:  0xbad,
			Index:  0,
			Reason: ident.InvalidLabelLDH,
		}, "label 2989 starts with '-'"},

		{"InvalidLabelLDH end", &ident.InvalidLabelError{
			Data:   []byte{0, '-'},
			Label:  0xbad,
			Index:  1,
			Reason: ident.InvalidLabelLDH,
		}, "label 2989 ends with '-'"},

		{"InvalidLabelLDH", &ident.InvalidLabelError{
			Data:   []byte{0},
			Label:  0xbad,
			Index:  0,
			Reason: ident.InvalidLabelLDH,
		}, `label 2989 contains invalid byte '\x00' at index 0`},

		{"InvalidLabelShort", &ident.InvalidLabelError{
			Label:  0xf00d,
			Reason: ident.InvalidLabelShort,
		}, "label 61453 is empty"},

		{"InvalidLabelLong", &ident.InvalidLabelError{
			Label:  0xf00d,
			Reason: ident.InvalidLabelLong,
		}, "label 61453 is longer than 63 bytes"},

		{"InvalidLabelError", &ident.InvalidLabelError{
			Label:  0xcafe,
			Reason: 0xbadf00d,
		}, "invalid label 51966 at byte 0"},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			if got := tc.err.Error(); got != tc.want {
				t.Errorf("Error: %q, want %q", got, tc.want)
			}
		})
	}
}