package execution_test

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

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

// fakeNexus stands in for the Nexus entity registry: whatever is in entities
// exists, anything else is a 404, and err simulates Nexus being unreachable.
type fakeNexus struct {
	entities map[string]*nexusclient.Entity
	err      error
	calls    int
}

func (f *fakeNexus) GetEntity(ctx context.Context, id string) (*nexusclient.Entity, error) {
	f.calls++
	if f.err != nil {
		return nil, f.err
	}
	if e, ok := f.entities[id]; ok {
		return e, nil
	}
	return nil, nexusclient.ErrEntityNotFound
}

func newTargetEngine(t *testing.T, nexus execution.EntityLookup) (*execution.Engine, *storage.Store) {
	t.Helper()
	store, err := storage.Open(filepath.Join(t.TempDir(), "hexis.db"))
	if err != nil {
		t.Fatalf("open storage: %v", err)
	}
	t.Cleanup(func() { store.Close() })

	reg := provider.NewRegistry()
	reg.Register(&fakeProvider{name: "fake"})

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

func activeNexus() *fakeNexus {
	return &fakeNexus{entities: map[string]*nexusclient.Entity{
		"ent_container_maven": {ID: "ent_container_maven", Type: "container", State: "active"},
		"ent_host_homesrv":    {ID: "ent_host_homesrv", Type: "host", State: "active"},
		"ent_retired_thing":   {ID: "ent_retired_thing", Type: "container", State: "retired"},
	}}
}

// TestExecute_RejectsFreeTextTarget pins ECOSYSTEM-SPEC.md §4.3: a target
// that is not a canonical ent_ ID is refused without even asking Nexus.
func TestExecute_RejectsFreeTextTarget(t *testing.T) {
	nexus := activeNexus()
	eng, store := newTargetEngine(t, nexus)
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
	})

	for _, target := range []string{"maven", "the maven container", "container_maven", "ent_", "ent_bad id", ""} {
		_, err := eng.Execute(&domain.ExecuteRequest{CapabilityID: cap.ID, TargetEntityID: target})
		if !errors.Is(err, execution.ErrTargetMalformed) {
			t.Errorf("target %q: expected ErrTargetMalformed, got %v", target, err)
		}
	}
	if nexus.calls != 0 {
		t.Errorf("malformed targets must not reach Nexus, got %d calls", nexus.calls)
	}
}

func TestExecute_RejectsUnknownTarget(t *testing.T) {
	eng, store := newTargetEngine(t, activeNexus())
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
	})

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

func TestExecute_RejectsWrongTargetType(t *testing.T) {
	eng, store := newTargetEngine(t, activeNexus())
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
	})

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

func TestExecute_RejectsRetiredTarget(t *testing.T) {
	eng, store := newTargetEngine(t, activeNexus())
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
	})

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

func TestExecute_AcceptsMatchingTarget(t *testing.T) {
	eng, store := newTargetEngine(t, activeNexus())
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
	})

	res, err := eng.Execute(&domain.ExecuteRequest{CapabilityID: cap.ID, TargetEntityID: "ent_container_maven"})
	if err != nil {
		t.Fatalf("expected success, got %v", err)
	}
	if res.Execution.Status != domain.ExecutionSucceeded {
		t.Fatalf("expected succeeded, got %q (%s)", res.Execution.Status, res.Execution.Error)
	}
}

// TestExecute_EmptyTargetTypesStillRequiresRealEntity documents the deliberate
// meaning of an empty TargetTypes: no *type* constraint, but the entity must
// still exist and be active. It is not a bypass.
func TestExecute_EmptyTargetTypesStillRequiresRealEntity(t *testing.T) {
	eng, store := newTargetEngine(t, activeNexus())
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = nil
	})

	if _, err := eng.Execute(&domain.ExecuteRequest{CapabilityID: cap.ID, TargetEntityID: "ent_nope"}); !errors.Is(err, execution.ErrTargetNotFound) {
		t.Fatalf("expected ErrTargetNotFound, got %v", err)
	}
	if _, err := eng.Execute(&domain.ExecuteRequest{CapabilityID: cap.ID, TargetEntityID: "ent_host_homesrv"}); err != nil {
		t.Fatalf("any existing type should be accepted, got %v", err)
	}
}

// TestExecute_FailsClosedWhenNexusUnreachable is the whole point of the
// guard: a Nexus outage must not degrade into accepting arbitrary targets.
func TestExecute_FailsClosedWhenNexusUnreachable(t *testing.T) {
	eng, store := newTargetEngine(t, &fakeNexus{err: errors.New("connection refused")})
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
	})

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

// TestCreateConfirmation_ValidatesTarget stops a confirmation being minted
// for a target that execute would later refuse.
func TestCreateConfirmation_ValidatesTarget(t *testing.T) {
	eng, store := newTargetEngine(t, activeNexus())
	cap := mustCreateCapability(t, store, func(c *domain.Capability) {
		c.TargetTypes = []string{"container"}
		c.RequiresConfirmation = true
	})

	if _, err := eng.CreateConfirmation(cap.ID, "just some words", "test", nil); !errors.Is(err, execution.ErrTargetMalformed) {
		t.Fatalf("expected ErrTargetMalformed, got %v", err)
	}
	if _, err := eng.CreateConfirmation(cap.ID, "ent_host_homesrv", "test", nil); !errors.Is(err, execution.ErrTargetTypeMismatch) {
		t.Fatalf("expected ErrTargetTypeMismatch, got %v", err)
	}
	if _, err := eng.CreateConfirmation(cap.ID, "ent_container_maven", "test", nil); err != nil {
		t.Fatalf("expected valid target to be accepted, got %v", err)
	}
}