package observation

import (
	"context"
	"errors"
	"fmt"
	"path/filepath"
	"testing"
	"time"

	_ "modernc.org/sqlite"

	"github.com/tegwick/fluid-core/internal/contract"
	"github.com/tegwick/fluid-core/internal/evidence"
)

func newRegistry(t *testing.T) (*PressureRegistry, *evidence.SQLStore) {
	t.Helper()
	store, err := evidence.OpenSQLite(context.Background(), filepath.Join(t.TempDir(), "e.db"))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = store.Close() })
	return NewPressureRegistry(store, "hall-publishing"), store
}

// inefficientTraffic reproduces the Blueprint section 33 shape: several
// consumers listing a collection repeatedly to find one record.
func inefficientTraffic() []contract.FluidTelemetry {
	var events []contract.FluidTelemetry
	for _, consumer := range []string{"c-1", "c-2", "c-3", "c-4"} {
		for chain := 0; chain < 3; chain++ {
			start := time.Duration(chain) * time.Hour
			for i := 0; i < 4; i++ {
				events = append(events,
					req(consumer, start+time.Duration(i)*time.Second, "GET", "/customers/{id}/invoices", 200))
			}
		}
	}
	return events
}

func TestClassifierFindsInefficientUsage(t *testing.T) {
	c := NewClassifier(DefaultClassifierOptions(), NewTopologyAnalyzer())

	findings := c.Classify(inefficientTraffic())
	if len(findings) == 0 {
		t.Fatal("no findings from clearly inefficient traffic")
	}

	var found *Finding
	for i := range findings {
		if findings[i].Class == contract.PressureClassSuccessfulButInefficientUsage {
			found = &findings[i]
		}
	}
	if found == nil {
		t.Fatalf("inefficient usage not classified; got %v", classesOf(findings))
	}
	if found.Consumers != 4 {
		t.Errorf("consumers = %d, want 4", found.Consumers)
	}
	if len(found.Evidence) == 0 {
		t.Error("a finding with no evidence references is not auditable")
	}
	if found.Confidence <= 0 || found.Confidence > 1 {
		t.Errorf("confidence out of range: %v", found.Confidence)
	}
}

func TestClassifierMapsErrorsToPressureClasses(t *testing.T) {
	c := NewClassifier(DefaultClassifierOptions(), NewTopologyAnalyzer())

	var events []contract.FluidTelemetry
	for i, consumer := range []string{"c-1", "c-2", "c-3"} {
		for n := 0; n < 5; n++ {
			ev := errEv(consumer, time.Duration(i*10+n)*time.Minute, "/v1/latest",
				contract.FluidTelemetryErrorClassUnknownPath)
			events = append(events, ev)
		}
	}

	findings := c.Classify(events)
	if !hasClass(findings, contract.PressureClassMissingInterfaceCapability) {
		t.Errorf("repeated unknown-path errors did not yield missing capability; got %v", classesOf(findings))
	}
}

// TestAuthorizationFailureIsNotPressure: the interface working as designed is
// not a defect, and dressing it up as one would send the Daimon chasing a
// change that must not happen.
func TestAuthorizationFailureIsNotPressure(t *testing.T) {
	c := NewClassifier(DefaultClassifierOptions(), NewTopologyAnalyzer())

	var events []contract.FluidTelemetry
	for i, consumer := range []string{"c-1", "c-2", "c-3"} {
		for n := 0; n < 10; n++ {
			events = append(events, errEv(consumer, time.Duration(i*10+n)*time.Minute, "/v1/admin",
				contract.FluidTelemetryErrorClassAuthorization))
		}
	}

	for _, f := range c.Classify(events) {
		if len(f.Evidence) > 0 && f.Class == contract.PressureClassMissingInterfaceCapability {
			t.Errorf("authorization failures were classified as pressure: %+v", f)
		}
	}
}

func TestClassifierNeedsIndependentConsumers(t *testing.T) {
	c := NewClassifier(DefaultClassifierOptions(), NewTopologyAnalyzer())

	var events []contract.FluidTelemetry
	for n := 0; n < 50; n++ {
		events = append(events, errEv("only-one", time.Duration(n)*time.Minute, "/v1/x",
			contract.FluidTelemetryErrorClassUnknownPath))
	}

	if findings := c.Classify(events); len(findings) != 0 {
		t.Errorf("one consumer's behaviour became interface pressure: %v", classesOf(findings))
	}
}

// TestRecordIsIdempotent is what stops re-analysing a window from minting a new
// pressure record on every pass.
func TestRecordIsIdempotent(t *testing.T) {
	ctx := context.Background()
	reg, _ := newRegistry(t)
	c := NewClassifier(DefaultClassifierOptions(), NewTopologyAnalyzer())

	findings := c.Classify(inefficientTraffic())
	if len(findings) == 0 {
		t.Fatal("no findings")
	}

	first, err := reg.RecordAll(ctx, findings)
	if err != nil {
		t.Fatal(err)
	}
	second, err := reg.RecordAll(ctx, findings)
	if err != nil {
		t.Fatal(err)
	}

	if len(first) != len(second) {
		t.Fatalf("record counts differ between runs: %d then %d", len(first), len(second))
	}
	for i := range first {
		if first[i].ID != second[i].ID {
			t.Errorf("re-recording minted a new id: %s then %s", first[i].ID, second[i].ID)
		}
	}

	all, err := reg.List(ctx, "")
	if err != nil {
		t.Fatal(err)
	}
	if len(all) != len(first) {
		t.Errorf("registry holds %d records after two identical runs, want %d", len(all), len(first))
	}
}

// TestFirstSeenIsNotOverwritten: how long the interface has had a problem is
// evidence, and it is what makes an old pressure worth prioritizing.
func TestFirstSeenIsNotOverwritten(t *testing.T) {
	ctx := context.Background()
	reg, _ := newRegistry(t)

	old := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
	f := Finding{
		Class:     contract.PressureClassPoorDiscoverability,
		Summary:   "consumers repeatedly send an unsupported filter",
		Consumers: 3, Occurrences: 30,
		Severity: 0.4, Confidence: 0.6,
		Evidence:    []contract.EvidenceRef{"route:GET /entries"},
		FirstSeen:   old,
		LastSeen:    old.Add(time.Hour),
		Fingerprint: "poor:GET /entries",
	}

	if _, err := reg.Record(ctx, f); err != nil {
		t.Fatal(err)
	}

	later := f
	later.FirstSeen = old.AddDate(0, 6, 0)
	later.LastSeen = old.AddDate(0, 6, 1)
	got, err := reg.Record(ctx, later)
	if err != nil {
		t.Fatal(err)
	}

	if !got.FirstSeen.Equal(old) {
		t.Errorf("first_seen was overwritten: %s, want %s", got.FirstSeen, old)
	}
	if !got.LastSeen.Equal(later.LastSeen) {
		t.Errorf("last_seen was not extended: %s", got.LastSeen)
	}
}

// TestDismissedPressureStaysDismissed: an operator's decision that something is
// not worth acting on must survive the next analysis run.
func TestDismissedPressureStaysDismissed(t *testing.T) {
	ctx := context.Background()
	reg, _ := newRegistry(t)

	f := Finding{
		Class:     contract.PressureClassOutOfScopeDemand,
		Summary:   "consumers ask for a capability outside the interface boundary",
		Consumers: 5, Occurrences: 40,
		Severity: 0.5, Confidence: 0.7,
		Evidence:    []contract.EvidenceRef{"route:GET /billing"},
		FirstSeen:   base,
		LastSeen:    base.Add(time.Hour),
		Fingerprint: "out-of-scope:GET /billing",
	}

	p, err := reg.Record(ctx, f)
	if err != nil {
		t.Fatal(err)
	}

	actor := contract.Actor{Type: contract.ActorTypeHuman, ID: "worsch"}
	if err := reg.SetStatus(ctx, p.ID, contract.FluidPressureStatusDISMISSED, actor,
		"billing belongs to the payments interface"); err != nil {
		t.Fatal(err)
	}

	if _, err := reg.Record(ctx, f); !errors.Is(err, ErrDismissed) {
		t.Errorf("a dismissed pressure was silently reopened: %v", err)
	}

	// A batch run must skip it rather than fail.
	if _, err := reg.RecordAll(ctx, []Finding{f}); err != nil {
		t.Errorf("RecordAll failed on a dismissed pressure: %v", err)
	}

	got, err := reg.Get(ctx, p.ID)
	if err != nil {
		t.Fatal(err)
	}
	if got.Status != contract.FluidPressureStatusDISMISSED {
		t.Errorf("status = %s, want DISMISSED", got.Status)
	}
}

func TestStatusChangeRequiresAReason(t *testing.T) {
	ctx := context.Background()
	reg, _ := newRegistry(t)

	p, err := reg.Record(ctx, Finding{
		Class: contract.PressureClassPoorDiscoverability, Summary: "s",
		Consumers: 2, Occurrences: 5, Evidence: []contract.EvidenceRef{"route:x"},
		FirstSeen: base, LastSeen: base, Fingerprint: "fp",
	})
	if err != nil {
		t.Fatal(err)
	}

	actor := contract.Actor{Type: contract.ActorTypeHuman, ID: "worsch"}
	if err := reg.SetStatus(ctx, p.ID, contract.FluidPressureStatusDISMISSED, actor, ""); err == nil {
		t.Error("a dismissal with no reason was accepted")
	}
}

func TestLinkHypothesisMovesToAnalyzing(t *testing.T) {
	ctx := context.Background()
	reg, store := newRegistry(t)

	p, err := reg.Record(ctx, Finding{
		Class: contract.PressureClassSuccessfulButInefficientUsage, Summary: "s",
		Consumers: 3, Occurrences: 12, Evidence: []contract.EvidenceRef{"route:x"},
		FirstSeen: base, LastSeen: base, Fingerprint: "fp",
	})
	if err != nil {
		t.Fatal(err)
	}

	if err := reg.LinkHypothesis(ctx, p.ID, "H-1"); err != nil {
		t.Fatal(err)
	}
	// Linking must reject a mis-prefixed id rather than store nonsense.
	if err := reg.LinkHypothesis(ctx, p.ID, "R-1"); err == nil {
		t.Error("a revision id was accepted as a hypothesis link")
	}

	got, err := reg.Get(ctx, p.ID)
	if err != nil {
		t.Fatal(err)
	}
	if got.Status != contract.FluidPressureStatusANALYZING {
		t.Errorf("status = %s, want ANALYZING", got.Status)
	}
	if len(got.LinkedHypotheses) != 1 {
		t.Errorf("linked hypotheses = %v", got.LinkedHypotheses)
	}

	// Linking twice must not duplicate.
	if err := reg.LinkHypothesis(ctx, p.ID, "H-1"); err != nil {
		t.Fatal(err)
	}
	got, _ = reg.Get(ctx, p.ID)
	if len(got.LinkedHypotheses) != 1 {
		t.Errorf("duplicate link recorded: %v", got.LinkedHypotheses)
	}

	events, err := store.Events(ctx, evidence.EventFilter{EntityID: string(p.ID)})
	if err != nil {
		t.Fatal(err)
	}
	if len(events) < 2 {
		t.Errorf("lifecycle transitions left too few events: %d", len(events))
	}
}

func TestListOrdersBySeverity(t *testing.T) {
	ctx := context.Background()
	reg, _ := newRegistry(t)

	for i, sev := range []float64{0.2, 0.9, 0.5} {
		_, err := reg.Record(ctx, Finding{
			Class:     contract.PressureClassPoorDiscoverability,
			Summary:   fmt.Sprintf("finding %d", i),
			Consumers: 3, Occurrences: 10,
			Severity: sev, Confidence: 0.5,
			Evidence:    []contract.EvidenceRef{contract.EvidenceRef(fmt.Sprintf("route:%d", i))},
			FirstSeen:   base,
			LastSeen:    base,
			Fingerprint: fmt.Sprintf("fp-%d", i),
		})
		if err != nil {
			t.Fatal(err)
		}
	}

	got, err := reg.List(ctx, "")
	if err != nil {
		t.Fatal(err)
	}
	if len(got) != 3 {
		t.Fatalf("got %d records", len(got))
	}
	for i := 1; i < len(got); i++ {
		if unit(got[i-1].Severity) < unit(got[i].Severity) {
			t.Error("records are not ordered by severity")
		}
	}
}

func classesOf(fs []Finding) []contract.PressureClass {
	out := make([]contract.PressureClass, len(fs))
	for i, f := range fs {
		out[i] = f.Class
	}
	return out
}

func hasClass(fs []Finding, want contract.PressureClass) bool {
	for _, f := range fs {
		if f.Class == want {
			return true
		}
	}
	return false
}