package alert

import (
	"errors"
	"testing"
	"time"
)

func signal(id, rule, evaluation string, state State, labels map[string]string) Signal {
	return Signal{InstanceID: id, RuleID: rule, RuleVersionID: "version-1", Severity: SeverityDegraded, State: state, EvaluationKey: evaluation, ObservedAt: time.Date(2026, time.January, 1, 12, 0, 0, 0, time.UTC), Labels: labels, GroupBy: []string{"host", "application"}, SuppressWhen: []string{"host.unreachable", "dns.failure", "source.unavailable"}}
}

func TestBuildFingerprintIsStableAndIncludesRuleBehavior(t *testing.T) {
	first, err := BuildFingerprint("rule-1", "version-1", "entity-1", map[string]string{"application": "media", "host": "pulse"})
	if err != nil {
		t.Fatal(err)
	}
	second, err := BuildFingerprint("rule-1", "version-1", "entity-1", map[string]string{"host": "pulse", "application": "media"})
	if err != nil {
		t.Fatal(err)
	}
	if first != second || len(first) != 64 {
		t.Fatalf("fingerprint instability: %q %q", first, second)
	}
	changedVersion, err := BuildFingerprint("rule-1", "version-2", "entity-1", map[string]string{"host": "pulse", "application": "media"})
	if err != nil {
		t.Fatal(err)
	}
	if changedVersion == first {
		t.Fatal("rule version did not affect fingerprint")
	}
	tooMany := make(map[string]string, MaxFingerprintLabels+1)
	for i := 0; i <= MaxFingerprintLabels; i++ {
		tooMany["label"+string(rune('a'+i))] = "value"
	}
	if _, err := BuildFingerprint("rule-1", "version-1", "entity-1", tooMany); !errors.Is(err, ErrInvalidAlertIdentity) {
		t.Fatalf("too many labels error = %v", err)
	}
}

func TestGroupAndDeduplicateSignalsAreDeterministic(t *testing.T) {
	inputs := []Signal{
		signal("instance-b", "rule-1", "slot-1", StateFiring, map[string]string{"host": "pulse", "application": "media"}),
		signal("instance-a", "rule-1", "slot-1", StateFiring, map[string]string{"host": "pulse", "application": "media"}),
		signal("instance-a", "rule-1", "slot-1", StateFiring, map[string]string{"host": "pulse", "application": "media"}),
		signal("instance-c", "rule-1", "slot-1", StateFiring, map[string]string{"host": "other", "application": "media"}),
	}
	deduplicated, err := DeduplicateSignals(inputs)
	if err != nil {
		t.Fatal(err)
	}
	if len(deduplicated) != 3 {
		t.Fatalf("deduplicated signals = %d, want 3", len(deduplicated))
	}
	groups, err := GroupSignals(deduplicated)
	if err != nil {
		t.Fatal(err)
	}
	if len(groups) != 2 || len(groups[0].Signals) != 1 || len(groups[1].Signals) != 2 {
		t.Fatalf("unexpected groups: %#v", groups)
	}
	if groups[0].Key > groups[1].Key {
		t.Fatal("groups are not sorted")
	}
}

func TestSuppressionScenariosRemainInspectablyBounded(t *testing.T) {
	base := signal("instance-1", "rule-service", "slot-1", StateFiring, map[string]string{"host": "pulse", "application": "web"})
	tests := []struct {
		name   string
		cause  Cause
		want   bool
		reason string
	}{
		{name: "host outage", cause: Cause{Key: "host.unreachable", State: StateFiring, Confirmed: true}, want: true, reason: "dependency_failure"},
		{name: "dns outage", cause: Cause{Key: "dns.failure", State: StateAcknowledged, Confidence: .9}, want: true, reason: "dependency_failure"},
		{name: "source outage", cause: Cause{Key: "source.unavailable", State: StateUnknown, Confirmed: true}, want: true, reason: "source_outage"},
		{name: "low confidence", cause: Cause{Key: "host.unreachable", State: StateFiring, Confidence: .5}, want: false, reason: "no_active_suppression_cause"},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			decision, err := EvaluateSuppression(base, []Cause{test.cause})
			if err != nil {
				t.Fatal(err)
			}
			if decision.Suppressed != test.want || decision.Reason != test.reason {
				t.Fatalf("decision = %#v, want suppressed=%v reason=%s", decision, test.want, test.reason)
			}
		})
	}
	resolved := base
	resolved.State = StateResolved
	decision, err := EvaluateSuppression(resolved, []Cause{{Key: "host.unreachable", State: StateFiring, Confirmed: true}})
	if err != nil {
		t.Fatal(err)
	}
	if decision.Suppressed {
		t.Fatal("resolved alert was suppressed")
	}
}