package whois_test

import (
	"bufio"
	"context"
	"errors"
	"io"
	"net"
	"slices"
	"strings"
	"sync"
	"syscall"
	"testing"
	"time"

	"git.eeqj.de/sneak/routewatch/internal/whois"
)

// The servers LookupASN asks: IANA first, then the RIR IANA refers it to.
const (
	ianaServer = "whois.iana.org:43"
	ripeServer = "whois.ripe.net:43"
)

// testASN is the AS the tests look up, and asQuery the query for it.
const (
	testASN = 3333
	asQuery = "AS3333"
)

// The fake servers' answers are keyed by a server's address, a space and a
// query. These are the keys of the queries LookupASN sends for testASN:
// IANA's, then RIPE's, which asks RIPE to leave out person and role
// objects.
const (
	ianaQuery = ianaServer + " " + asQuery
	ripeQuery = ripeServer + " --no-personal " + asQuery
)

// ianaReferral is IANA's answer for an AS in a block it gave to RIPE.
const ianaReferral = `% IANA WHOIS server

refer:        whois.ripe.net

as-block:     3154-3353
organisation: Assigned by RIPE NCC
whois:        whois.ripe.net
changed:      2002-09-01
source:       IANA
`

// ripeRecord is RIPE's answer for the AS when asked to leave out person and
// role objects: the abuse address as a comment, the AS's object and the
// organisation object it refers to.
const ripeRecord = `% This is the RIPE Database query service.
% The objects are in RPSL format.

% Note: --no-personal means ALL personal data has been filtered from this output.

% Information related to 'AS3333'

% Abuse contact for 'AS3333' is 'abuse@ripe.net'

aut-num:        AS3333
as-name:        RIPE-NCC-AS
org:            ORG-RIEN1-RIPE
admin-c:        BRD-RIPE
tech-c:         OPS4-RIPE
abuse-c:        OPS4-RIPE
mnt-by:         RIPE-NCC-MNT
created:        2002-09-17T13:08:32Z
last-modified:  2024-01-09T08:55:41Z
source:         RIPE

organisation:   ORG-RIEN1-RIPE
org-name:       Reseaux IP Europeens Network Coordination Centre (RIPE NCC)
country:        NL
org-type:       RIR
address:        P.O. Box 10096
address:        1001EB Amsterdam
abuse-c:        OPS4-RIPE
created:        2012-03-09T13:08:29Z
last-modified:  2024-03-26T10:55:38Z
source:         RIPE
`

// The error lines with which RIPE refuses a query: access denied to the
// host, and the host's limit on returned objects reached.
const (
	ripeAccessDenied = "%ERROR:201: access denied for 192.0.2.1"
	ripeLimitReached = "%ERROR:202: access control limit reached"
)

// ripeRefusal is RIPE's answer to a host it no longer serves.
const ripeRefusal = `% This is the RIPE Database query service.
% The objects are in RPSL format.
%
` + ripeAccessDenied + `
%
% Sorry, access from your host has been permanently
% denied because of a repeated excessive querying.
`

// apnicAfrinicRecord is the answer of APNIC or AFRINIC for the AS when asked
// to leave out person and role objects. Like RIPE's, it holds the abuse
// address as a comment, the AS's object and the organisation object.
const apnicAfrinicRecord = `% Abuse contact for 'AS3333' is 'abuse@example.net'

aut-num:        AS3333
as-name:        EXAMPLE-AS
org:            ORG-EXAMPLE1
admin-c:        EX1-TEST
last-modified:  2026-08-26T00:40:00Z

organisation:   ORG-EXAMPLE1
org-name:       Example Networks
country:        ZA
address:        1 Example Road
`

// ianaPrivateUse is IANA's answer for a private-use AS: its block and no
// referral.
const ianaPrivateUse = `% IANA WHOIS server

as-block:     64512-65534
organisation: Reserved for Private Use
descr:        Reserved for Private Use
source:       IANA
`

// ianaNoObject is IANA's answer when it has nothing for the query.
const ianaNoObject = `% IANA WHOIS server
% This query returned 0 objects.
`

// fillerLine is one of the lines a server that does not stop keeps sending.
const fillerLine = "remarks:        and more\n"

// endlessAnswerSize is how many bytes of filler lines that server sends:
// four times the client's cap on an answer.
const endlessAnswerSize = 4 << 20

// fakeServers returns a DialContext for a whois.Client that connects to a
// fake server at each address answers names. Each key of answers is a
// server's address, a space and a query, and its value is that server's
// answer to that query. A server reads one query and sends its answer, or
// nothing for a query it has no answer for. Connecting to any other address
// is refused.
func fakeServers(
	t *testing.T, answers map[string]string,
) func(context.Context, string, string) (net.Conn, error) {
	t.Helper()

	addresses := make(map[string]bool)

	for key := range answers {
		address, _, _ := strings.Cut(key, " ")
		addresses[address] = true
	}

	var servers sync.WaitGroup

	t.Cleanup(servers.Wait)

	return func(_ context.Context, _, address string) (net.Conn, error) {
		if !addresses[address] {
			return nil, syscall.ECONNREFUSED
		}

		client, server := net.Pipe()

		servers.Go(func() {
			defer func() { _ = server.Close() }()

			query, _ := bufio.NewReader(server).ReadString('\n')
			answer := answers[address+" "+strings.TrimSpace(query)]
			_, _ = io.WriteString(server, answer)
		})

		return client, nil
	}
}

// lookUp looks testASN up with fake servers sending answers.
func lookUp(
	t *testing.T, answers map[string]string,
) (*whois.ASNInfo, error) {
	t.Helper()

	client := whois.NewClient()
	client.DialContext = fakeServers(t, answers)

	return client.LookupASN(t.Context(), testASN)
}

// TestLookupASNReadsTheRIRAnswer looks up an AS IANA refers to RIPE. RIPE
// answers only a query that leaves out person and role objects, and its
// answer to that still fills the AS's fields: the abuse address from the
// comment line, and the organisation's name and country from its object.
// The dates are the AS's: IANA's "changed:" line dates its block.
func TestLookupASNReadsTheRIRAnswer(t *testing.T) {
	t.Parallel()

	info, err := lookUp(t, map[string]string{
		ianaQuery: ianaReferral,
		ripeQuery: ripeRecord,
	})
	if err != nil {
		t.Fatalf("LookupASN: %v", err)
	}

	got := []string{
		info.ASName, info.OrgID, info.OrgName, info.CountryCode,
		info.AbuseEmail, info.RIR,
	}
	want := []string{
		"RIPE-NCC-AS", "ORG-RIEN1-RIPE",
		"Reseaux IP Europeens Network Coordination Centre (RIPE NCC)", "NL",
		"abuse@ripe.net", whois.RIRRIPE,
	}

	if !slices.Equal(got, want) {
		t.Errorf("LookupASN = AS name, org ID, org name, country, abuse "+
			"address, RIR %q; want %q", got, want)
	}

	wantRegDate := time.Date(2002, 9, 17, 13, 8, 32, 0, time.UTC)
	if info.RegDate == nil || !info.RegDate.Equal(wantRegDate) {
		t.Errorf("LookupASN registered = %v, want %v",
			info.RegDate, wantRegDate)
	}

	wantLastMod := time.Date(2024, 1, 9, 8, 55, 41, 0, time.UTC)
	if info.LastMod == nil || !info.LastMod.Equal(wantLastMod) {
		t.Errorf("LookupASN last modified = %v, want %v",
			info.LastMod, wantLastMod)
	}
}

// TestLookupASNAsksAPNICAndAFRINICToLeaveOutPersonalData looks up an AS at
// APNIC and at AFRINIC. Each answers only a query that leaves out person
// and role objects, as RIPE does. That one answer still holds the
// organisation object, so the organisation's name and country are filled.
func TestLookupASNAsksAPNICAndAFRINICToLeaveOutPersonalData(t *testing.T) {
	t.Parallel()

	for _, server := range []string{"whois.apnic.net", "whois.afrinic.net"} {
		t.Run(server, func(t *testing.T) {
			t.Parallel()

			address := server + ":43"

			info, err := lookUp(t, map[string]string{
				ianaQuery:                             "refer:        " + server + "\n",
				address + " --no-personal " + asQuery: apnicAfrinicRecord,
			})
			if err != nil {
				t.Fatalf("LookupASN: %v", err)
			}

			got := []string{
				info.ASName, info.OrgName, info.CountryCode, info.AbuseEmail,
			}
			want := []string{
				"EXAMPLE-AS", "Example Networks", "ZA", "abuse@example.net",
			}

			if !slices.Equal(got, want) {
				t.Errorf("LookupASN = AS name, org name, country, abuse "+
					"address %q; want %q", got, want)
			}
		})
	}
}

// TestLookupASNReportsARefusal looks up an AS IANA refers to RIPE when RIPE
// refuses the query, with each of the error lines RIPE refuses with. The
// error holds RIPE's line, so the log says why the lookup failed.
func TestLookupASNReportsARefusal(t *testing.T) {
	t.Parallel()

	for _, line := range []string{ripeAccessDenied, ripeLimitReached} {
		t.Run(line, func(t *testing.T) {
			t.Parallel()

			_, err := lookUp(t, map[string]string{
				ianaQuery: ianaReferral,
				ripeQuery: "% This is the RIPE Database query service.\n" +
					line + "\n",
			})
			if err == nil || !strings.Contains(err.Error(), line) {
				t.Errorf("LookupASN error = %v, want one holding %q",
					err, line)
			}
		})
	}
}

// TestLookupASNFailsWhenTheRIRGivesNoAnswer looks up an AS IANA refers to
// RIPE when RIPE's server refuses the connection, and when it answers only
// with an error. Neither is a lookup that found the AS.
func TestLookupASNFailsWhenTheRIRGivesNoAnswer(t *testing.T) {
	t.Parallel()

	for name, answers := range map[string]map[string]string{
		"connection refused": {ianaQuery: ianaReferral},
		"only an error":      {ianaQuery: ianaReferral, ripeQuery: ripeRefusal},
	} {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			_, err := lookUp(t, answers)
			if err == nil || errors.Is(err, whois.ErrNoReferral) {
				t.Errorf("LookupASN error = %v, want one that is not "+
					"ErrNoReferral", err)
			}
		})
	}
}

// TestLookupASNReportsNoReferral looks up a private-use AS, which IANA
// refers to no RIR.
func TestLookupASNReportsNoReferral(t *testing.T) {
	t.Parallel()

	_, err := lookUp(t, map[string]string{ianaQuery: ianaPrivateUse})
	if !errors.Is(err, whois.ErrNoReferral) {
		t.Errorf("LookupASN error = %v, want ErrNoReferral", err)
	}
}

// TestLookupASNFailsWhenIANAAnswersNoBlock looks up an AS when IANA answers
// with neither a referral nor the AS's block. That is not IANA saying no
// RIR holds the AS.
func TestLookupASNFailsWhenIANAAnswersNoBlock(t *testing.T) {
	t.Parallel()

	_, err := lookUp(t, map[string]string{ianaQuery: ianaNoObject})
	if err == nil || errors.Is(err, whois.ErrNoReferral) {
		t.Errorf("LookupASN error = %v, want one that is not ErrNoReferral",
			err)
	}
}

// TestLookupASNFailsWhenTheRIRAnswerDoesNotEnd looks up an AS whose RIR
// server follows the record with filler lines far past any real answer.
// The client stops reading at its cap and fails instead of keeping them.
func TestLookupASNFailsWhenTheRIRAnswerDoesNotEnd(t *testing.T) {
	t.Parallel()

	endless := ripeRecord +
		strings.Repeat(fillerLine, endlessAnswerSize/len(fillerLine))

	_, err := lookUp(t, map[string]string{
		ianaQuery: ianaReferral,
		ripeQuery: endless,
	})
	if err == nil || errors.Is(err, whois.ErrNoReferral) {
		t.Errorf("LookupASN error = %v, want one that is not ErrNoReferral",
			err)
	}
}

// TestLookupASNFailsOnAReferralToAnotherServer looks up an AS when IANA's
// answer refers it to a server none of the five RIRs run, with a port and
// without. The client follows a referral only to an RIR's server, so it
// fails instead of asking that server, which would answer with a record.
func TestLookupASNFailsOnAReferralToAnotherServer(t *testing.T) {
	t.Parallel()

	// Each case maps the server on the "refer:" line to the address the
	// client would dial to follow it. IANA's answer also names the AS's
	// block, so a client that dropped the referral would report no RIR.
	for refer, address := range map[string]string{
		"whois.example.net:8080": "whois.example.net:8080",
		"whois.example.net":      "whois.example.net:43",
	} {
		t.Run(refer, func(t *testing.T) {
			t.Parallel()

			_, err := lookUp(t, map[string]string{
				ianaQuery: "refer:        " + refer + "\n\n" +
					"as-block:     3154-3353\n",
				address + " " + asQuery: ripeRecord,
			})
			if err == nil || errors.Is(err, whois.ErrNoReferral) {
				t.Errorf("LookupASN error = %v, want one that is not "+
					"ErrNoReferral", err)
			}
		})
	}
}