package importer

import (
	"context"
	"errors"
	"strings"
	"testing"

	"evobgp/internal/store"
)

type importBackend struct {
	store.Backend
	created  int
	onCreate func()
}

func (s *importBackend) GetModule(string, string) (*store.Module, error) {
	return &store.Module{Type: "AS_PREFIXES"}, nil
}
func (s *importBackend) ListCommunities(string) ([]*store.Community, error) { return nil, nil }
func (s *importBackend) CreateASEntry(_, _ string, e *store.ASEntry) (*store.ASEntry, error) {
	s.created++
	if s.onCreate != nil {
		s.onCreate()
	}
	return e, nil
}

func TestCSVByteLimitRejectsValidTruncatedPrefix(t *testing.T) {
	header := "asn,community\n"
	for _, extra := range []int{0, 1} {
		s := &importBackend{}
		body := header + strings.Repeat("\n", MaxCSVBytes-len(header)) + strings.Repeat("\n", extra)
		_, err := ImportModuleEntriesCSV(context.Background(), s, "tenant", "module", strings.NewReader(body))
		if extra == 0 && err != nil {
			t.Fatalf("exact limit: %v", err)
		}
		if extra == 1 && !errors.Is(err, ErrCSVTooLarge) {
			t.Fatalf("limit+1: %v", err)
		}
		if s.created != 0 {
			t.Fatal("oversized import created entries")
		}
	}
}

func TestCSVRowLimitCheckedBeforeWrites(t *testing.T) {
	for _, header := range []string{"", "asn,community\n"} {
		for _, extra := range []int{0, 1} {
			s := &importBackend{}
			_, err := ImportModuleEntriesCSV(context.Background(), s, "tenant", "module", strings.NewReader(header+strings.Repeat("64512,\n", MaxCSVRows+extra)))
			if extra == 0 && (err != nil || s.created != MaxCSVRows) {
				t.Fatalf("exact rows: created=%d err=%v", s.created, err)
			}
			if extra == 1 && (!errors.Is(err, ErrCSVTooLarge) || s.created != 0) {
				t.Fatalf("rows+1: created=%d err=%v", s.created, err)
			}
		}
	}
}

func TestCSVCancellationStopsFurtherWrites(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	s := &importBackend{onCreate: cancel}
	_, err := ImportModuleEntriesCSV(ctx, s, "tenant", "module", strings.NewReader("asn,community\n64512,\n64513,\n"))
	if !errors.Is(err, context.Canceled) || s.created != 1 {
		t.Fatalf("created=%d err=%v", s.created, err)
	}
}

func TestCSVFieldLimitAndQuotedFields(t *testing.T) {
	for _, tc := range []struct {
		name, input string
		oversized   bool
	}{
		{"exact", "64512," + strings.Repeat(",", MaxCSVFields-2) + "\n", false},
		{"over", "64512," + strings.Repeat(",", MaxCSVFields-1) + "\n", true},
		{"many_fields", strings.Repeat(",", 1<<20) + "\n", true},
		{"quoted_extra", "64512,,\"" + strings.Repeat(",", 128) + "\nquoted \"\"text\"\"\"\n", false},
	} {
		t.Run(tc.name, func(t *testing.T) {
			s := &importBackend{}
			_, err := ImportModuleEntriesCSV(context.Background(), s, "tenant", "module", strings.NewReader(tc.input))
			if tc.oversized {
				if !errors.Is(err, ErrCSVTooLarge) || s.created != 0 {
					t.Fatalf("created=%d err=%v", s.created, err)
				}
			} else if err != nil || s.created != 1 {
				t.Fatalf("created=%d err=%v", s.created, err)
			}
		})
	}
}