package activitypool

import (
	"context"
	"errors"
	"testing"
	"time"

	healthDomain "proxy-pool/internal/domain/health"
	proxyDomain "proxy-pool/internal/domain/proxy"
)

func TestMemoryPoolAppliesGlobalObservationAtomically(t *testing.T) {
	now := time.Date(2026, 7, 31, 11, 0, 0, 0, time.UTC)
	pool := seededHealthPool(t, now)
	if _, err := pool.ApplyHealth(context.Background(), HealthUpdate{
		ProxyID: "proxy-a", CheckedAt: now.Add(time.Second), NextState: proxyDomain.StateChecking,
	}); err != nil {
		t.Fatalf("ApplyHealth(checking): %v", err)
	}
	failed, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-1", false, now.Add(2*time.Second)), MaxConsecutiveFailures: 3,
	})
	if err != nil || failed.State != proxyDomain.StateUnhealthy || failed.GlobalHealth.ConsecutiveFailures != 1 ||
		!failed.GlobalHealth.UnhealthySince.Equal(now.Add(2*time.Second)) {
		t.Fatalf("ApplyGlobalObservation(initial failure) = %+v, %v", failed, err)
	}
	if _, err := pool.ApplyHealth(context.Background(), HealthUpdate{
		ProxyID: "proxy-a", CheckedAt: now.Add(3 * time.Second), NextState: proxyDomain.StateChecking,
	}); err != nil {
		t.Fatalf("ApplyHealth(recheck): %v", err)
	}
	available, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-2", true, now.Add(4*time.Second)), MaxConsecutiveFailures: 3,
	})
	if err != nil || available.State != proxyDomain.StateAvailable || available.GlobalHealth.ConsecutiveFailures != 0 ||
		!available.GlobalHealth.UnhealthySince.IsZero() ||
		available.Proxy.LastSuccessAt == nil || !available.Proxy.LastSuccessAt.Equal(now.Add(4*time.Second)) {
		t.Fatalf("ApplyGlobalObservation(recovery) = %+v, %v", available, err)
	}
}

func TestMemoryPoolStartsConditionalDrainForOwnedProxyPastUnhealthyGrace(t *testing.T) {
	now := time.Date(2026, 8, 2, 13, 0, 0, 0, time.UTC)
	pool := seededHealthPool(t, now)
	if _, err := pool.ApplyHealth(context.Background(), HealthUpdate{
		ProxyID: "proxy-a", CheckedAt: now.Add(time.Second), NextState: proxyDomain.StateChecking,
	}); err != nil {
		t.Fatalf("ApplyHealth(checking) = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-available", true, now.Add(2*time.Second)), MaxConsecutiveFailures: 1,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(available) = %v", err)
	}
	assignment, err := pool.Assign(context.Background(), now.Add(3*time.Second), "proxy-a", "worker-a", time.Minute)
	if err != nil {
		t.Fatalf("Assign() = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-suspect", false, now.Add(4*time.Second)), MaxConsecutiveFailures: 2,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(suspect) = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-unhealthy", false, now.Add(5*time.Second)), MaxConsecutiveFailures: 2,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(unhealthy) = %v", err)
	}

	command := UnhealthySweepCommand{
		Now: now.Add(7 * time.Second), Limit: 8, RemoveAfterByUpstream: map[string]time.Duration{"provider-a": time.Second},
	}
	result, err := pool.SweepUnhealthy(context.Background(), command)
	if err != nil || result.Removed != 0 || result.DeferredOwned != 1 || len(result.DrainCandidates) != 1 {
		t.Fatalf("SweepUnhealthy(owned) = %+v, %v", result, err)
	}
	candidate := result.DrainCandidates[0]
	if candidate.ProxyID != "proxy-a" || candidate.WorkerID != "worker-a" || candidate.AssignmentEpoch != assignment.Epoch ||
		!candidate.UnhealthySince.Equal(now.Add(5*time.Second)) {
		t.Fatalf("SweepUnhealthy() candidate = %+v", candidate)
	}
	if _, exists := pool.entryByIDLocked("proxy-a"); !exists {
		t.Fatal("owned unhealthy proxy was removed")
	}
	if started, err := pool.BeginUnhealthyDrain(context.Background(), command.Now, candidate); err != nil || !started {
		t.Fatalf("BeginUnhealthyDrain() = %t, %v", started, err)
	}
	if started, err := pool.BeginUnhealthyDrain(context.Background(), command.Now, candidate); err != nil || started {
		t.Fatalf("BeginUnhealthyDrain(idempotent) = %t, %v", started, err)
	}
	if err := pool.AcknowledgeDrain(context.Background(), "proxy-a", "worker-a", assignment.Epoch, 0, 0); err != nil {
		t.Fatalf("AcknowledgeDrain() = %v", err)
	}
	command.Now = now.Add(9 * time.Second)
	if result, err := pool.SweepUnhealthy(context.Background(), command); err != nil || result.Removed != 1 || result.DeferredOwned != 0 || len(result.DrainCandidates) != 0 {
		t.Fatalf("SweepUnhealthy(unowned) = %+v, %v", result, err)
	}
	if _, exists := pool.entryByIDLocked("proxy-a"); exists {
		t.Fatal("unowned unhealthy proxy remains after grace")
	}
}

func TestMemoryPoolRejectsUnhealthyDrainCandidateAfterRecovery(t *testing.T) {
	now := time.Date(2026, 8, 2, 13, 0, 0, 0, time.UTC)
	pool := seededHealthPool(t, now)
	if _, err := pool.ApplyHealth(context.Background(), HealthUpdate{
		ProxyID: "proxy-a", CheckedAt: now.Add(time.Second), NextState: proxyDomain.StateChecking,
	}); err != nil {
		t.Fatalf("ApplyHealth(checking) = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-available", true, now.Add(2*time.Second)), MaxConsecutiveFailures: 1,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(available) = %v", err)
	}
	assignment, err := pool.Assign(context.Background(), now.Add(3*time.Second), "proxy-a", "worker-a", time.Minute)
	if err != nil {
		t.Fatalf("Assign() = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-suspect", false, now.Add(4*time.Second)), MaxConsecutiveFailures: 2,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(suspect) = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-unhealthy", false, now.Add(5*time.Second)), MaxConsecutiveFailures: 2,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(unhealthy) = %v", err)
	}
	command := UnhealthySweepCommand{
		Now: now.Add(7 * time.Second), Limit: 1, RemoveAfterByUpstream: map[string]time.Duration{"provider-a": time.Second},
	}
	result, err := pool.SweepUnhealthy(context.Background(), command)
	if err != nil || len(result.DrainCandidates) != 1 {
		t.Fatalf("SweepUnhealthy() = %+v, %v", result, err)
	}
	if _, err := pool.ApplyHealth(context.Background(), HealthUpdate{
		ProxyID: "proxy-a", CheckedAt: now.Add(7 * time.Second), NextState: proxyDomain.StateChecking,
	}); err != nil {
		t.Fatalf("ApplyHealth(rechecking) = %v", err)
	}
	if _, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{
		Observation: healthObservation("task-recovered", true, now.Add(8*time.Second)), MaxConsecutiveFailures: 1,
	}); err != nil {
		t.Fatalf("ApplyGlobalObservation(recovered) = %v", err)
	}
	if started, err := pool.BeginUnhealthyDrain(context.Background(), now.Add(8*time.Second), result.DrainCandidates[0]); err != nil || started {
		t.Fatalf("BeginUnhealthyDrain(recovered) = %t, %v", started, err)
	}
	if current, ok, err := pool.Get(context.Background(), "proxy-a"); err != nil || !ok || current.Epoch != assignment.Epoch || current.Draining {
		t.Fatalf("Get(recovered) = %+v, %t, %v", current, ok, err)
	}
}

func TestMemoryPoolGlobalObservationReplayDoesNotIncreaseFailureStreak(t *testing.T) {
	now := time.Date(2026, 7, 31, 11, 0, 0, 0, time.UTC)
	pool := seededHealthPool(t, now)
	if _, err := pool.ApplyHealth(context.Background(), HealthUpdate{
		ProxyID: "proxy-a", CheckedAt: now.Add(time.Second), NextState: proxyDomain.StateChecking,
	}); err != nil {
		t.Fatalf("ApplyHealth(checking): %v", err)
	}
	command := GlobalHealthCommand{Observation: healthObservation("task-1", false, now.Add(2*time.Second)), MaxConsecutiveFailures: 3}
	first, err := pool.ApplyGlobalObservation(context.Background(), command)
	if err != nil {
		t.Fatalf("ApplyGlobalObservation(first): %v", err)
	}
	replayed, err := pool.ApplyGlobalObservation(context.Background(), command)
	if err != nil || replayed.GlobalHealth != first.GlobalHealth {
		t.Fatalf("ApplyGlobalObservation(replay) = %+v, %v", replayed, err)
	}
	conflicting := command
	conflicting.Observation.Success = true
	conflicting.Observation.FailureClass = ""
	if _, err := pool.ApplyGlobalObservation(context.Background(), conflicting); !errors.Is(err, healthDomain.ErrConflictingObservation) {
		t.Fatalf("ApplyGlobalObservation(conflict) error = %v, want ErrConflictingObservation", err)
	}
}

func TestMemoryPoolRejectsTargetObservationFromGlobalStore(t *testing.T) {
	now := time.Date(2026, 7, 31, 11, 0, 0, 0, time.UTC)
	pool := seededHealthPool(t, now)
	_, err := pool.ApplyGlobalObservation(context.Background(), GlobalHealthCommand{Observation: healthDomain.Observation{
		TaskID: "task-target", ProxyID: "proxy-a", Level: healthDomain.LevelTarget, RoutingName: "route-a",
		TargetURL: "https://target.example/", Success: false, FailureClass: "target_403", ObservedAt: now.Add(time.Second),
	}, MaxConsecutiveFailures: 2})
	if !errors.Is(err, ErrInvalidHealthUpdate) {
		t.Fatalf("ApplyGlobalObservation(target) error = %v, want ErrInvalidHealthUpdate", err)
	}
}

func seededHealthPool(t *testing.T, now time.Time) *MemoryPool {
	t.Helper()
	pool := NewMemoryPool()
	_, err := pool.UpsertFetched(context.Background(), "provider-a", FetchedBatch{
		ObservedAt: now, ConfiguredTTL: time.Minute, MaxSize: 1,
		Proxies: []proxyDomain.Proxy{{
			ID: "proxy-a", Scheme: proxyDomain.SchemeHTTP, Host: "192.0.2.10", Port: 8080,
		}},
	})
	if err != nil {
		t.Fatalf("UpsertFetched(): %v", err)
	}
	return pool
}

func healthObservation(taskID string, success bool, observedAt time.Time) healthDomain.Observation {
	observation := healthDomain.Observation{
		TaskID: taskID, ProxyID: "proxy-a", Level: healthDomain.LevelBasic,
		Success: success, Latency: 10 * time.Millisecond, ObservedAt: observedAt,
	}
	if !success {
		observation.FailureClass = "timeout"
	}
	return observation
}