package execution_test

import (
	"encoding/json"
	"errors"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/kami/hexis/internal/domain"
	"github.com/kami/hexis/internal/execution"
	"github.com/kami/hexis/internal/provider"
	"github.com/kami/hexis/internal/storage"
)

func newContractTestEngine(t *testing.T) (*execution.Engine, *storage.Store) {
	t.Helper()
	prov := &fakeProvider{name: "fake"}
	dir := t.TempDir()
	store, err := storage.Open(filepath.Join(dir, "hexis.db"))
	if err != nil {
		t.Fatalf("open storage: %v", err)
	}
	t.Cleanup(func() { store.Close() })

	reg := provider.NewRegistry()
	reg.Register(prov)

	return execution.New(store, reg), store
}

// TestContract_IdempotencyKeyReplay validates that re-executing with the
// same idempotency_key returns the existing execution without side effects.
func TestContract_IdempotencyKeyReplay(t *testing.T) {
	eng, store := newContractTestEngine(t)
	cap := mustCreateCapability(t, store, nil)

	// First execution with idempotency key
	res1, err := eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
		IdempotencyKey: "idem-unique-1",
	})
	if err != nil {
		t.Fatalf("first execute: %v", err)
	}
	if res1.Execution.Status != domain.ExecutionSucceeded {
		t.Fatalf("expected succeeded, got %s", res1.Execution.Status)
	}

	// Replay with same idempotency key must return the same execution
	res2, err := eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
		IdempotencyKey: "idem-unique-1",
	})
	if err != nil {
		t.Fatalf("replay execute: %v", err)
	}
	if res2.Execution.ID != res1.Execution.ID {
		t.Errorf("expected same execution ID on replay, got %s vs %s", res2.Execution.ID, res1.Execution.ID)
	}
	if res2.Execution.Status != res1.Execution.Status {
		t.Errorf("expected same status on replay, got %s vs %s", res2.Execution.Status, res1.Execution.Status)
	}
}

// TestContract_EmptyIdempotencyKeyNotReplayed validates that requests
// without an idempotency key always create new executions.
func TestContract_EmptyIdempotencyKeyNotReplayed(t *testing.T) {
	eng, store := newContractTestEngine(t)
	cap := mustCreateCapability(t, store, nil)

	res1, err := eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
	})
	if err != nil {
		t.Fatalf("execute 1: %v", err)
	}

	res2, err := eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
	})
	if err != nil {
		t.Fatalf("execute 2: %v", err)
	}

	if res2.Execution.ID == res1.Execution.ID {
		t.Error("expected different execution IDs for same request without idempotency key")
	}
}

// TestContract_EventPayloadFormat validates that all emitted events have
// the correct event type prefix and non-empty payloads where expected.
func TestContract_EventPayloadFormat(t *testing.T) {
	eng, store := newContractTestEngine(t)
	cap := mustCreateCapability(t, store, nil)

	eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
	})

	events, err := store.EventsAfter(0, 100)
	if err != nil {
		t.Fatalf("events: %v", err)
	}

	var seenStart, seenSucceed bool
	for _, evt := range events {
		if !strings.HasPrefix(string(evt.Type), "hexis.") {
			t.Errorf("event type %q doesn't start with 'hexis.'", evt.Type)
		}
		switch evt.Type {
		case domain.EventExecutionStarted:
			seenStart = true
			if _, ok := evt.Payload["capability_id"]; !ok {
				t.Error("execution.started event missing capability_id in payload")
			}
		case domain.EventExecutionSucceeded:
			seenSucceed = true
		case domain.EventCapabilityRegistered:
			// Registered by mustCreateCapability
		}
	}
	if !seenStart {
		t.Error("expected execution.started event")
	}
	if !seenSucceed {
		t.Error("expected execution.succeeded event")
	}
}

// TestContract_CapabilityRegisteredEmittedOnce validates that
// EventCapabilityRegistered is emitted only once per capability creation,
// not also by the execution engine.
func TestContract_CapabilityRegisteredEmittedOnce(t *testing.T) {
	_, store := newContractTestEngine(t)
	// This test validates that creating a capability emits exactly one
	// registration event. The handler calls AppendEvent directly with
	// EventCapabilityRegistered. The engine does not emit this event.
	// We verify by looking at the event log after a capability is created.

	// Create capability directly through store (simulating handler behavior)
	now := time.Now().UTC()
	cap := &domain.Capability{
		ID:          domain.NewCapabilityID(),
		Name:        "test.cap.unique",
		Provider:    "fake",
		Operation:   "noop",
		Risk:        "low",
		ReadOnly:    false,
		Enabled:     true,
		CreatedAt:   now,
		UpdatedAt:   now,
		Version:     1,
		TargetTypes: []string{},
		Attributes:  map[string]any{},
	}
	if err := store.CreateCapability(cap); err != nil {
		t.Fatalf("create capability: %v", err)
	}

	// Emit registration event (as handler does)
	store.AppendEvent(&domain.Event{
		ID:        domain.NewEventID(),
		Type:      domain.EventCapabilityRegistered,
		Timestamp: now,
		Payload:   map[string]any{"capability_id": cap.ID, "name": cap.Name},
	})

	events, err := store.EventsAfter(0, 100)
	if err != nil {
		t.Fatalf("events: %v", err)
	}

	count := 0
	for _, evt := range events {
		if evt.Type == domain.EventCapabilityRegistered {
			payload, _ := json.Marshal(evt.Payload)
			if strings.Contains(string(payload), cap.ID) {
				count++
			}
		}
	}
	if count != 1 {
		t.Errorf("expected exactly 1 EventCapabilityRegistered for cap %s, got %d", cap.ID, count)
	}
}

// TestContract_EventCorrelationFieldPopulated validates that correlation_id
// and causation_id set on an ExecuteRequest propagate onto the execution's
// emitted events.
func TestContract_EventCorrelationFieldPopulated(t *testing.T) {
	eng, store := newContractTestEngine(t)
	cap := mustCreateCapability(t, store, nil)

	eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
		CorrelationID:  "corr-789",
		CausationID:    "cause-012",
	})

	events, err := store.EventsAfter(0, 100)
	if err != nil {
		t.Fatalf("events: %v", err)
	}

	found := false
	for _, evt := range events {
		if evt.Type == domain.EventExecutionStarted {
			found = true
			if evt.CorrelationID != "corr-789" {
				t.Errorf("expected correlation_id corr-789, got %q", evt.CorrelationID)
			}
			if evt.CausationID != "cause-012" {
				t.Errorf("expected causation_id cause-012, got %q", evt.CausationID)
			}
		}
	}
	if !found {
		t.Fatalf("expected an execution.started event")
	}
}

// TestContract_ExecutionStatusDeniedNotEmitted documents that the
// execution.denied event type is defined but never emitted.
func TestContract_ExecutionDeniedNotEmitted(t *testing.T) {
	eng, store := newContractTestEngine(t)
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.Enabled = false
	})

	_, err := eng.Execute(&domain.ExecuteRequest{
		CapabilityID:   cap.ID,
		TargetEntityID: "ent_x",
	})
	if !errors.Is(err, domain.ErrCapabilityDisabled) {
		t.Fatalf("expected ErrCapabilityDisabled, got %v", err)
	}

	events, _ := store.EventsAfter(0, 100)
	for _, evt := range events {
		if evt.Type == domain.EventExecutionDenied {
			t.Errorf("execution.denied event emitted but expected to not be in use")
		}
	}
}