package main

import (
	"errors"
	"io"
	"slices"
	"strings"
	"testing"
	"testing/iotest"
	"time"
)

// parseTimeLimit is how long a test waits for parseCSV to return before it
// fails.
const parseTimeLimit = 2 * time.Second

// TestParseCSVReadsTodaysLayout parses an as.csv with the country code column
// that the source added after the description. It expects each AS with its
// handle and description spelled exactly as in the file, accents included.
func TestParseCSVReadsTodaysLayout(t *testing.T) {
	t.Parallel()

	const asCSV = `asn,handle,description,country-code
1,LVLT-1,Level 3 Parent LLC,US
1251,FUNDACAO-AMPARO-PESQUISA,FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO SÃO PAULO,BR
`

	got, err := parseCSV(strings.NewReader(asCSV))
	if err != nil {
		t.Fatalf("parseCSV: %v", err)
	}

	want := []ASInfo{
		{ASN: 1, Handle: "LVLT-1", Description: "Level 3 Parent LLC"},
		{
			ASN:    1251,
			Handle: "FUNDACAO-AMPARO-PESQUISA",
			Description: "FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO " +
				"SÃO PAULO",
		},
	}

	if !slices.Equal(got, want) {
		t.Errorf("parseCSV = %+v, want %+v", got, want)
	}
}

// TestParseCSVRejectsAnotherHeader parses files whose first columns are not
// the AS number, the handle and the description. It expects an error rather
// than a list read from the wrong columns.
func TestParseCSVRejectsAnotherHeader(t *testing.T) {
	t.Parallel()

	for _, asCSV := range []string{
		"asn,handle\n1,LVLT-1\n",
		"asn,description,handle\n1,Level 3 Parent LLC,LVLT-1\n",
	} {
		_, err := parseCSV(strings.NewReader(asCSV))
		if err == nil {
			t.Errorf("parseCSV(%q): no error", asCSV)
		}
	}
}

// TestParseCSVRejectsAFileWithNoASes parses files that hold no AS, one with
// only the header and one whose only record has no valid AS number. It
// expects errNoASes, so that make asupdate keeps the old list.
func TestParseCSVRejectsAFileWithNoASes(t *testing.T) {
	t.Parallel()

	for _, asCSV := range []string{
		"asn,handle,description,country-code\n",
		"asn,handle,description,country-code\nAS1,LVLT-1,Level 3,US\n",
	} {
		_, err := parseCSV(strings.NewReader(asCSV))
		if !errors.Is(err, errNoASes) {
			t.Errorf("parseCSV(%q) = %v, want %v", asCSV, err, errNoASes)
		}
	}
}

// TestParseCSVSkipsARecordThatDoesNotParse parses an as.csv with a record
// that has too few fields between two valid records. It expects both valid
// ASes and no error, so that one bad record does not stop make asupdate.
func TestParseCSVSkipsARecordThatDoesNotParse(t *testing.T) {
	t.Parallel()

	const asCSV = "asn,handle,description,country-code\n" +
		"1,LVLT-1,Level 3 Parent LLC,US\n" +
		"2,UDEL-DCN\n" +
		"3,MIT-GATEWAYS,Massachusetts Institute of Technology,US\n"

	got, err := parseCSV(strings.NewReader(asCSV))
	if err != nil {
		t.Fatalf("parseCSV: %v", err)
	}

	want := []ASInfo{
		{ASN: 1, Handle: "LVLT-1", Description: "Level 3 Parent LLC"},
		{
			ASN:         3,
			Handle:      "MIT-GATEWAYS",
			Description: "Massachusetts Institute of Technology",
		},
	}

	if !slices.Equal(got, want) {
		t.Errorf("parseCSV = %+v, want %+v", got, want)
	}
}

// TestParseCSVStopsWhenTheDownloadBreaksOff parses an as.csv whose download
// breaks off after the first record. From then on every read fails, as on a
// broken connection. It expects parseCSV to return that error, so that make
// asupdate keeps the old list.
func TestParseCSVStopsWhenTheDownloadBreaksOff(t *testing.T) {
	t.Parallel()

	const asCSV = "asn,handle,description,country-code\n" +
		"1,LVLT-1,Level 3 Parent LLC,US\n"

	download := io.MultiReader(
		strings.NewReader(asCSV), iotest.ErrReader(io.ErrUnexpectedEOF))

	// parseCSV runs on its own goroutine, so that a parseCSV that never
	// returns fails the test instead of hanging it.
	parsed := make(chan error, 1)

	go func() {
		_, err := parseCSV(download)
		parsed <- err
	}()

	select {
	case err := <-parsed:
		if !errors.Is(err, io.ErrUnexpectedEOF) {
			t.Errorf("parseCSV = %v, want %v", err, io.ErrUnexpectedEOF)
		}
	case <-time.After(parseTimeLimit):
		t.Fatalf("parseCSV did not return within %v", parseTimeLimit)
	}
}