package cms_test

import (
	"crypto/elliptic"
	"crypto/sha1"
	"errors"
	"testing"

	"g.activething.com/go/DateKeys/internal/cms"
	"g.activething.com/go/DateKeys/internal/cms/cmstest"
	"g.activething.com/go/DateKeys/internal/der"
)

// The keys and the certificates of the tests of the reader, made once: an
// RSA key takes time to generate. The certificates are made field by field,
// with the profile of spec §29.10, and are valid from 2020 to 2040.
var (
	ecKey  = cmstest.ECKey(elliptic.P256())
	ecKey2 = cmstest.ECKey(elliptic.P256())
	rsaKey = cmstest.RSAKey(2048)

	ana  = cmstest.NewCert(cmstest.CertSpec{CN: "Ana López"}, ecKey)
	luis = cmstest.NewCert(cmstest.CertSpec{CN: "Luis Gómez"}, rsaKey)
	tsa  = cmstest.NewCert(cmstest.CertSpec{CN: "TSA de prueba"}, ecKey2)
)

// path joins paths of cmstest.Edit.
func path(parts ...any) []int {
	var out []int
	for _, p := range parts {
		switch x := p.(type) {
		case int:
			out = append(out, x)
		case []int:
			out = append(out, x...)
		}
	}
	return out
}

// firstSignerInfo is the path of the first SignerInfo of a signature.
func firstSignerInfo(b []byte) []int { return path(cmstest.SignerInfosPath(b), 0) }

// wantForm checks that the signature b breaks the profile (F1).
func wantForm(t *testing.T, name string, b []byte) {
	t.Helper()
	if _, err := cms.ParseSignature(b); !errors.Is(err, cms.ErrForm) {
		t.Errorf("%s: %v, want a form error", name, err)
	}
}

// signerOf parses the signature b, which must meet the profile, and returns
// its only SignerInfo.
func signerOf(t *testing.T, name string, b []byte) *cms.SignerInfo {
	t.Helper()
	sd, err := cms.ParseSignature(b)
	if err != nil || len(sd.Signers) != 1 {
		t.Fatalf("%s: %v", name, err)
	}
	return sd.Signers[0]
}

// resultOf is the result of the only SignerInfo of the signature b over msg.
func resultOf(t *testing.T, name string, b []byte) cms.Result {
	t.Helper()
	return signerOf(t, name, b).Check(msg)
}

func isForm(err error) bool { return errors.Is(err, cms.ErrForm) }

func isAlgorithm(err error) bool { return errors.Is(err, cms.ErrAlgorithm) }

// contentOf returns the content octets of the DER element b.
func contentOf(b []byte) []byte {
	c, err := der.Content(b)
	if err != nil {
		panic(err)
	}
	return c
}

func sha1Sum(b []byte) []byte {
	s := sha1.Sum(b)
	return s[:]
}