package backend

import (
	"fmt"
	"reflect"
	"testing"
)

type dedupTargetStub struct {
	headers []MessageHeader
	bodies  map[uint32][]byte
	deleted []uint32
}

func (s *dedupTargetStub) Folders() ([]TargetFolder, error) { return nil, nil }
func (s *dedupTargetStub) Delim() string                    { return "/" }
func (s *dedupTargetStub) EnsureFolder(string) error        { return nil }
func (s *dedupTargetStub) Append(string, RawMessage) error  { return nil }
func (s *dedupTargetStub) Headers(string, int, int) ([]MessageHeader, error) {
	return s.headers, nil
}
func (s *dedupTargetStub) AllHeaders(string) ([]MessageHeader, error) { return s.headers, nil }
func (s *dedupTargetStub) FetchOne(_ string, uid uint32) (RawMessage, error) {
	body, ok := s.bodies[uid]
	if !ok {
		return RawMessage{}, fmt.Errorf("missing uid %d", uid)
	}
	return RawMessage{Body: body}, nil
}
func (s *dedupTargetStub) DeleteUIDs(_ string, uids []uint32) error {
	s.deleted = append(s.deleted, uids...)
	return nil
}
func (s *dedupTargetStub) Close() error { return nil }

func TestDedupTargetFolderProtectsDifferentBodiesWithSameMessageID(t *testing.T) {
	sameA := []byte("Message-ID: <same@example.com>\r\n\r\nA")
	sameB := []byte("Message-ID: <same@example.com>\r\n\r\nB")
	dst := &dedupTargetStub{
		headers: []MessageHeader{
			{UID: 1, MessageID: "same@example.com"},
			{UID: 2, MessageID: "same@example.com"},
			{UID: 3, MessageID: "same@example.com"},
		},
		bodies: map[uint32][]byte{1: sameA, 2: sameA, 3: sameB},
	}
	report, err := dedupTargetFolder(dst, "INBOX", true)
	if err != nil {
		t.Fatal(err)
	}
	if report.Groups != 1 || report.ExtraCopies != 1 || report.VariantGroups != 1 {
		t.Fatalf("unexpected report: %#v", report)
	}
	if !reflect.DeepEqual(dst.deleted, []uint32{2}) {
		t.Fatalf("deleted=%v, want only exact duplicate UID 2", dst.deleted)
	}
}

func TestDedupTargetFolderAbortsBeforeDeleteWhenBodyCannotBeVerified(t *testing.T) {
	dst := &dedupTargetStub{
		headers: []MessageHeader{{UID: 1, MessageID: "same@example.com"}, {UID: 2, MessageID: "same@example.com"}},
		bodies:  map[uint32][]byte{1: []byte("Message-ID: <same@example.com>\r\n\r\nA")},
	}
	if _, err := dedupTargetFolder(dst, "INBOX", true); err == nil {
		t.Fatal("expected safe dedup to fail when a body cannot be fetched")
	}
	if len(dst.deleted) != 0 {
		t.Fatalf("deleted despite incomplete verification: %v", dst.deleted)
	}
}