package checker

import (
	"context"
	"encoding/json"
	"errors"
	"reflect"
	"testing"
	"time"

	sdk "git.happydns.org/checker-sdk-go/checker"
)

func mustJSONForRule(t *testing.T, v any) json.RawMessage {
	t.Helper()
	b, err := json.Marshal(v)
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}
	return b
}

// stubObs is a minimal sdk.ObservationGetter for the rule tests. It is
// keyed by ObservationKey so a single instance can serve a Get and any
// number of GetRelated lookups.
type stubObs struct {
	data    *SMTPData
	getErr  error
	related map[sdk.ObservationKey][]sdk.RelatedObservation
}

func (s *stubObs) Get(_ context.Context, _ sdk.ObservationKey, dest any) error {
	if s.getErr != nil {
		return s.getErr
	}
	if s.data == nil {
		return errors.New("no data")
	}
	b, err := json.Marshal(s.data)
	if err != nil {
		return err
	}
	return json.Unmarshal(b, dest)
}

func (s *stubObs) GetRelated(_ context.Context, key sdk.ObservationKey) ([]sdk.RelatedObservation, error) {
	return s.related[key], nil
}

func TestSeverityToStatus(t *testing.T) {
	cases := []struct {
		sev  string
		want sdk.Status
	}{
		{SeverityCrit, sdk.StatusCrit},
		{SeverityWarn, sdk.StatusWarn},
		{SeverityInfo, sdk.StatusInfo},
		{"", sdk.StatusOK},
		{"bogus", sdk.StatusOK},
	}
	for _, c := range cases {
		if got := severityToStatus(c.sev); got != c.want {
			t.Errorf("%q → %v, want %v", c.sev, got, c.want)
		}
	}
}

func TestPassAndNotTestedStates(t *testing.T) {
	p := passState("c.ok", "fine")
	if p.Status != sdk.StatusOK || p.Code != "c.ok" || p.Message != "fine" {
		t.Errorf("passState: %+v", p)
	}
	n := notTestedState("c.skip", "n/a")
	if n.Status != sdk.StatusUnknown || n.Code != "c.skip" {
		t.Errorf("notTestedState: %+v", n)
	}
}

func TestIssueToState(t *testing.T) {
	is := Issue{
		Code: "x", Severity: SeverityWarn, Message: "m", Fix: "do",
		Endpoint: "1.2.3.4:25", Target: "mx",
	}
	st := issueToState(is)
	if st.Status != sdk.StatusWarn {
		t.Errorf("status: %v", st.Status)
	}
	if st.Subject != "1.2.3.4:25" {
		t.Errorf("subject (endpoint preferred): %q", st.Subject)
	}
	if st.Meta["fix"] != "do" || st.Meta["endpoint"] != "1.2.3.4:25" || st.Meta["target"] != "mx" {
		t.Errorf("meta: %+v", st.Meta)
	}
}

func TestIssueToState_TargetFallbackSubject(t *testing.T) {
	is := Issue{Code: "x", Severity: SeverityCrit, Target: "mx"}
	st := issueToState(is)
	if st.Subject != "mx" {
		t.Errorf("expected target subject, got %q", st.Subject)
	}
}

func TestIssueToState_NoMeta(t *testing.T) {
	is := Issue{Code: "x", Severity: SeverityInfo}
	st := issueToState(is)
	if st.Meta != nil {
		t.Errorf("meta should be nil when no fields set, got %+v", st.Meta)
	}
}

func TestStatesFromIssues(t *testing.T) {
	issues := []Issue{
		{Code: "a", Severity: SeverityCrit},
		{Code: "b", Severity: SeverityWarn},
	}
	states := statesFromIssues(issues)
	if len(states) != 2 {
		t.Fatalf("got %d", len(states))
	}
	if states[0].Code != "a" || states[1].Code != "b" {
		t.Errorf("order not preserved: %+v", states)
	}
}

func TestIssuesByCodes_FiltersAndKeepsOrder(t *testing.T) {
	d := &SMTPData{
		Domain:    "x",
		MX:        MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}},
		Endpoints: []EndpointProbe{{Target: "mx.x", IP: "1.2.3.4", Address: "1.2.3.4:25", Error: "boom"}},
	}
	got := issuesByCodes(d, CodeTCPUnreachable, CodeAllEndpointsDown, "smtp.does-not-exist")
	if len(got) != 2 {
		t.Fatalf("want 2 issues, got %d", len(got))
	}
	codes := []string{got[0].Code, got[1].Code}
	want := []string{CodeTCPUnreachable, CodeAllEndpointsDown}
	if !reflect.DeepEqual(codes, want) {
		t.Errorf("order: got %v, want %v", codes, want)
	}
}

func TestIssuesByCodes_EmptyCodes(t *testing.T) {
	if got := issuesByCodes(&SMTPData{}); got != nil {
		t.Errorf("expected nil, got %+v", got)
	}
}

func TestRules_ContainsAllExpectedNames(t *testing.T) {
	rules := Rules()
	got := map[string]bool{}
	for _, r := range rules {
		got[r.Name()] = true
		if r.Description() == "" {
			t.Errorf("%s: empty description", r.Name())
		}
	}
	want := []string{
		"smtp.null_mx", "smtp.mx_present", "smtp.mx_sanity",
		"smtp.endpoint_reachable", "smtp.banner_sanity", "smtp.ehlo_supported",
		"smtp.starttls_offered", "smtp.starttls_handshake", "smtp.auth_posture",
		"smtp.reverse_dns", "smtp.null_sender", "smtp.postmaster",
		"smtp.open_relay", "smtp.extension_posture", "smtp.ipv6_reachable",
		"smtp.tls_quality",
	}
	for _, n := range want {
		if !got[n] {
			t.Errorf("missing rule %q", n)
		}
	}
}

func TestNullMXRule_Detected(t *testing.T) {
	obs := &stubObs{data: &SMTPData{MX: MXLookup{NullMX: true}}}
	st := (&nullMXRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusInfo || st[0].Code != CodeNullMX {
		t.Errorf("got %+v", st)
	}
}

func TestNullMXRule_NotNull(t *testing.T) {
	obs := &stubObs{data: &SMTPData{Domain: "x", MX: MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}}}}
	st := (&nullMXRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusOK {
		t.Errorf("expected pass, got %+v", st)
	}
}

func TestNullMXRule_LoadError(t *testing.T) {
	obs := &stubObs{getErr: errors.New("boom")}
	st := (&nullMXRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusError {
		t.Errorf("expected error, got %+v", st)
	}
}

func TestSimpleConcernRule_PassWhenNoMatchingIssues(t *testing.T) {
	yes := true
	obs := &stubObs{data: &SMTPData{
		Domain:    "x",
		MX:        MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}},
		Endpoints: []EndpointProbe{{Target: "mx.x", IP: "1.2.3.4", Address: "1.2.3.4:25", TCPConnected: true, BannerReceived: true, BannerCode: 220, EHLOReceived: true, STARTTLSOffered: true, STARTTLSUpgraded: true, NullSenderAccepted: &yes, PostmasterAccepted: &yes, PTR: "mx.x", FCrDNSPass: true, HasPipelining: true, Has8BITMIME: true}},
	}}
	r := &simpleConcernRule{name: "smtp.endpoint_reachable", codes: []string{CodeTCPUnreachable}, passCode: "smtp.endpoint_reachable.ok", passMessage: "ok"}
	st := r.Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusOK {
		t.Errorf("expected single pass state, got %+v", st)
	}
}

func TestSimpleConcernRule_EmitsMatchingIssues(t *testing.T) {
	obs := &stubObs{data: &SMTPData{
		Domain:    "x",
		MX:        MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}},
		Endpoints: []EndpointProbe{{Target: "mx.x", IP: "1.2.3.4", Address: "1.2.3.4:25", Error: "boom"}},
	}}
	r := &simpleConcernRule{name: "smtp.endpoint_reachable", codes: []string{CodeTCPUnreachable, CodeAllEndpointsDown}, passCode: "smtp.endpoint_reachable.ok", passMessage: "ok"}
	st := r.Evaluate(context.Background(), obs, nil)
	if len(st) != 2 {
		t.Fatalf("want 2 states, got %d (%+v)", len(st), st)
	}
	if st[0].Status != sdk.StatusCrit {
		t.Errorf("expected crit status, got %v", st[0].Status)
	}
}

func TestSimpleConcernRule_NullMXSkipped(t *testing.T) {
	obs := &stubObs{data: &SMTPData{MX: MXLookup{NullMX: true}}}
	r := &simpleConcernRule{name: "smtp.starttls_offered", codes: []string{CodeSTARTTLSMissing}, passCode: "smtp.starttls_offered.ok"}
	st := r.Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusUnknown {
		t.Errorf("null MX should yield not-tested, got %+v", st)
	}
}

func TestSimpleConcernRule_LoadError(t *testing.T) {
	obs := &stubObs{getErr: errors.New("nope")}
	r := &simpleConcernRule{name: "smtp.x", codes: []string{CodeTCPUnreachable}, passCode: "ok"}
	st := r.Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusError {
		t.Errorf("got %+v", st)
	}
}

func TestTLSQualityRule_NoRelated(t *testing.T) {
	obs := &stubObs{data: &SMTPData{Domain: "x", MX: MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}}}}
	st := (&tlsQualityRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusUnknown {
		t.Errorf("expected not-tested, got %+v", st)
	}
}

func TestTLSQualityRule_NullMXSkipped(t *testing.T) {
	obs := &stubObs{data: &SMTPData{MX: MXLookup{NullMX: true}}}
	st := (&tlsQualityRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusUnknown {
		t.Errorf("got %+v", st)
	}
}

func TestTLSQualityRule_PassWhenRelatedClean(t *testing.T) {
	yes := true
	notAfter := time.Now().Add(365 * 24 * time.Hour)
	payload := map[string]any{"host": "mx.x", "port": 25, "chain_valid": yes, "hostname_match": yes, "not_after": notAfter}
	related := map[sdk.ObservationKey][]sdk.RelatedObservation{
		TLSRelatedKey: {{Data: mustJSONForRule(t, payload)}},
	}
	obs := &stubObs{
		data:    &SMTPData{Domain: "x", MX: MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}}},
		related: related,
	}
	st := (&tlsQualityRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) != 1 || st[0].Status != sdk.StatusOK {
		t.Errorf("expected ok pass, got %+v", st)
	}
}

func TestTLSQualityRule_RelatedIssuesFlow(t *testing.T) {
	payload := map[string]any{
		"host": "mx.x", "port": 25,
		"issues": []map[string]any{{"code": "cert.expired", "severity": "crit", "message": "expired"}},
	}
	related := map[sdk.ObservationKey][]sdk.RelatedObservation{
		TLSRelatedKey: {{Data: mustJSONForRule(t, payload)}},
	}
	obs := &stubObs{
		data:    &SMTPData{Domain: "x", MX: MXLookup{Records: []MXRecord{{Target: "mx.x", IPv4: []string{"1.2.3.4"}}}}},
		related: related,
	}
	st := (&tlsQualityRule{}).Evaluate(context.Background(), obs, nil)
	if len(st) == 0 || st[0].Status != sdk.StatusCrit {
		t.Errorf("expected crit, got %+v", st)
	}
}