package dmarc

import (
	"archive/zip"
	"bytes"
	"compress/gzip"
	"errors"
	"strings"
	"testing"
	"time"

	"github.com/mixeme/selfpost/internal/store"
)

// sampleXML and the messages in this file are composed by hand, in the shape
// RFC 7489 gives (Appendix C, the schema; § 7.2.1.1, application/gzip and the
// .xml.gz name). The org name is any reporter's; no report was copied.
const sampleXML = `<?xml version="1.0"?>
<feedback>
  <report_metadata>
    <org_name>google.com</org_name>
    <email>noreply@google.com</email>
    <report_id>12345</report_id>
    <date_range><begin>1723593600</begin><end>1723680000</end></date_range>
  </report_metadata>
  <policy_published>
    <domain>example.com</domain>
    <p>none</p><sp>none</sp><pct>100</pct>
    <adkim>r</adkim><aspf>r</aspf>
  </policy_published>
  <record>
    <row>
      <source_ip>203.0.113.10</source_ip>
      <count>10</count>
      <policy_evaluated>
        <disposition>none</disposition>
        <dkim>pass</dkim><spf>pass</spf>
      </policy_evaluated>
    </row>
    <identifiers><header_from>example.com</header_from></identifiers>
  </record>
  <record>
    <row>
      <source_ip>198.51.100.1</source_ip>
      <count>2</count>
      <policy_evaluated>
        <disposition>none</disposition>
        <dkim>fail</dkim><spf>fail</spf>
      </policy_evaluated>
    </row>
    <identifiers><header_from>example.com</header_from></identifiers>
  </record>
</feedback>`

func TestParseAggregateGzip(t *testing.T) {
	var buf bytes.Buffer
	zw := gzip.NewWriter(&buf)
	if _, err := zw.Write([]byte(sampleXML)); err != nil {
		t.Fatal(err)
	}
	if err := zw.Close(); err != nil {
		t.Fatal(err)
	}
	got, err := ParseAggregate(buf.Bytes())
	if err != nil {
		t.Fatalf("ParseAggregate: %v", err)
	}
	if got.Domain != "example.com" || got.Reporter != "google.com" {
		t.Fatalf("metadata = %+v", got)
	}
	if got.PassCount != 10 || got.FailCount != 2 {
		t.Fatalf("counts = %d pass %d fail", got.PassCount, got.FailCount)
	}
	if !got.PeriodBegin.Equal(time.Unix(1723593600, 0).UTC()) {
		t.Fatalf("period begin = %v", got.PeriodBegin)
	}
}

func TestIngestMessageStoresReport(t *testing.T) {
	st, err := store.Open(t.TempDir() + "/test.db")
	if err != nil {
		t.Fatal(err)
	}
	defer st.Close()
	if _, err := st.AddDomain("example.com", "selfpost"); err != nil {
		t.Fatal(err)
	}

	var gz bytes.Buffer
	zw := gzip.NewWriter(&gz)
	_, _ = zw.Write([]byte(sampleXML))
	_ = zw.Close()

	msg := bytes.NewBufferString(
		"From: noreply@google.com\r\n" +
			"To: dmarc-reports@mail.example.com\r\n" +
			"Subject: Report\r\n" +
			"Content-Type: application/gzip; name=\"report.xml.gz\"\r\n" +
			"\r\n",
	)
	// append raw gzip for simple single-part test
	msg.Write(gz.Bytes())

	if err := IngestMessage(st, msg, "dmarc-reports@mail.example.com", time.Now().UTC()); err != nil {
		t.Fatalf("IngestMessage: %v", err)
	}
	list, err := st.ListDMARCReports(store.DMARCReportScope{AllDomains: true}, 10)
	if err != nil {
		t.Fatal(err)
	}
	if len(list) != 1 {
		t.Fatalf("reports = %d", len(list))
	}
	if list[0].PassCount != 10 {
		t.Fatalf("pass = %d", list[0].PassCount)
	}
}

func TestHostedReportAddress(t *testing.T) {
	got := HostedReportAddress("mail.example.com", "Example.COM")
	want := "dmarc-reports+example.com@mail.example.com"
	if got != want {
		t.Fatalf("got %q want %q", got, want)
	}
}

func TestIngestMessageRejectsUnknownDomain(t *testing.T) {
	st, err := store.Open(t.TempDir() + "/test.db")
	if err != nil {
		t.Fatal(err)
	}
	defer st.Close()

	err = IngestMessage(st, bytes.NewBufferString(gzipMessage(t, sampleXML)), "dmarc-reports@mail.example.com", time.Now().UTC())
	if !errors.Is(err, ErrRejected) {
		t.Fatalf("report for an unconfigured domain: err = %v, want ErrRejected", err)
	}
	list, err := st.ListDMARCReports(store.DMARCReportScope{AllDomains: true}, 10)
	if err != nil {
		t.Fatal(err)
	}
	if len(list) != 0 {
		t.Fatalf("stored %d report(s) for an unconfigured domain", len(list))
	}
}

// A report claiming example.com must not be accepted at the address tagged for
// another domain, even when both domains are configured here.
func TestIngestMessageRejectsTagMismatch(t *testing.T) {
	st, err := store.Open(t.TempDir() + "/test.db")
	if err != nil {
		t.Fatal(err)
	}
	defer st.Close()
	if _, err := st.AddDomain("example.com", "selfpost"); err != nil {
		t.Fatal(err)
	}
	if _, err := st.AddDomain("other.example", "selfpost"); err != nil {
		t.Fatal(err)
	}

	err = IngestMessage(st, bytes.NewBufferString(gzipMessage(t, sampleXML)),
		"dmarc-reports+other.example@mail.example.com", time.Now().UTC())
	if !errors.Is(err, ErrRejected) {
		t.Fatalf("report at an address tagged for another domain: err = %v, want ErrRejected", err)
	}
}

// What cannot be read as a report is rejected, not put off: Postfix would
// offer the same bytes again for days.
func TestIngestMessageRejectsWhatIsNotAReport(t *testing.T) {
	st, err := store.Open(t.TempDir() + "/test.db")
	if err != nil {
		t.Fatal(err)
	}
	defer st.Close()
	if _, err := st.AddDomain("example.com", "selfpost"); err != nil {
		t.Fatal(err)
	}
	for name, msg := range map[string]string{
		"plain text":  "From: someone@example.net\r\nSubject: hello\r\n\r\nnot a report\r\n",
		"no headers":  "garbage",
		"broken gzip": "From: a@example.net\r\nContent-Type: application/gzip\r\n\r\nnot gzip at all",
	} {
		err := IngestMessage(st, bytes.NewBufferString(msg), "dmarc-reports+example.com@mail.example.com", time.Now().UTC())
		if !errors.Is(err, ErrRejected) {
			t.Errorf("%s: err = %v, want ErrRejected", name, err)
		}
	}
}

// A failing store is not the report's fault: the message is to be tried again.
func TestIngestMessageStoreFailureIsNotARejection(t *testing.T) {
	st, err := store.Open(t.TempDir() + "/test.db")
	if err != nil {
		t.Fatal(err)
	}
	if _, err := st.AddDomain("example.com", "selfpost"); err != nil {
		t.Fatal(err)
	}
	st.Close()
	err = IngestMessage(st, bytes.NewBufferString(gzipMessage(t, sampleXML)), "dmarc-reports+example.com@mail.example.com", time.Now().UTC())
	if err == nil || errors.Is(err, ErrRejected) {
		t.Fatalf("closed store: err = %v, want an error that is not ErrRejected", err)
	}
}

func TestTaggedDomain(t *testing.T) {
	cases := map[string]string{
		"dmarc-reports+example.com@mail.example.com": "example.com",
		"dmarc-reports@mail.example.com":             "",
		"postmaster+example.com@mail.example.com":    "",
		"not-an-address":                             "",
	}
	for addr, want := range cases {
		if got := TaggedDomain(addr); got != want {
			t.Errorf("TaggedDomain(%q) = %q, want %q", addr, got, want)
		}
	}
}

func TestParseAggregateFromZip(t *testing.T) {
	var buf bytes.Buffer
	zw := zip.NewWriter(&buf)
	w, err := zw.Create("report.xml")
	if err != nil {
		t.Fatal(err)
	}
	if _, err := w.Write([]byte(sampleXML)); err != nil {
		t.Fatal(err)
	}
	if err := zw.Close(); err != nil {
		t.Fatal(err)
	}

	got, err := ParseAggregate(buf.Bytes())
	if err != nil {
		t.Fatalf("ParseAggregate(zip): %v", err)
	}
	if got.Domain != "example.com" || got.PassCount != 10 {
		t.Fatalf("zip report = %+v", got)
	}
}

// gzipMessage wraps xml in the single-part gzip message the ingest pipe sees.
func gzipMessage(t *testing.T, xml string) string {
	t.Helper()
	var gz bytes.Buffer
	zw := gzip.NewWriter(&gz)
	if _, err := zw.Write([]byte(xml)); err != nil {
		t.Fatal(err)
	}
	if err := zw.Close(); err != nil {
		t.Fatal(err)
	}
	return "From: noreply@google.com\r\n" +
		"To: dmarc-reports@mail.example.com\r\n" +
		"Subject: Report\r\n" +
		"Content-Type: application/gzip; name=\"report.xml.gz\"\r\n" +
		"\r\n" + gz.String()
}

// pct is 100 when the report leaves it out (RFC 7489 § 6.3), and an explicit
// 0 - a policy applied to no message - stays 0 (assumptions C-M7).
func TestPolicyPct(t *testing.T) {
	for _, c := range []struct {
		pct  string
		want int
	}{
		{"<pct>100</pct>", 100},
		{"<pct>0</pct>", 0},
		{"<pct>25</pct>", 25},
		{"", 100},
		{"<pct/>", 100},
		{"<pct> 50 </pct>", 50},
		{"<pct>150</pct>", 100},
		{"<pct>-5</pct>", 0},
		{"<pct>x</pct>", 100},
	} {
		doc := strings.Replace(sampleXML, "<pct>100</pct>", c.pct, 1)
		got, err := ParseAggregate([]byte(doc))
		if err != nil {
			t.Fatalf("%q: %v", c.pct, err)
		}
		if got.PolicyPct != c.want {
			t.Errorf("%q: PolicyPct %d, want %d", c.pct, got.PolicyPct, c.want)
		}
	}
}