package kvm2

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"testing"
	"time"

	"github.com/digitalocean/go-libvirt"

	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
)

func TestGet_afterDeleteReturnsNotFound(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	id := fx.create(testName)
	if err := fx.p.Delete(fx.ctx, id); err != nil {
		t.Fatalf("Delete() error = %v", err)
	}
	inst, err := fx.p.Get(fx.ctx, id)
	if inst != nil {
		t.Errorf("Get after Delete = %+v, want nil", inst)
	}
	assertProviderError(t, err, "get", provider.ErrNotFound)
}

func TestGet_duringDeleteStillReturnsInstance(t *testing.T) {
	t.Parallel()
	t.Run("destroyed but still defined is stopped", func(t *testing.T) {
		t.Parallel()
		fx := newFixture(t, 1)
		id := fx.create(testName)
		fx.withDomain(testName, func(d *fakeDomain) { d.state = libvirt.DomainShutoff })
		inst := fx.get(id)
		if inst.State != provider.StateStopped || inst.UID != testUID {
			t.Errorf("Get = %+v, want Stopped with uid %s", inst, testUID)
		}
	})
	t.Run("undefine in flight still answers", func(t *testing.T) {
		t.Parallel()
		fx := newFixture(t, 1)
		id := fx.create(testName)
		release := fx.fake.blockOn("DomainUndefineFlags")
		done := make(chan error, 1)
		go func() { done <- fx.p.Delete(fx.ctx, id) }()
		waitFor(t, "the undefine to block", func() bool { return fx.fake.callCount("DomainUndefineFlags") == 1 })

		inst, err := fx.p.Get(fx.ctx, id)
		if err != nil {
			t.Fatalf("Get during Delete error = %v, want the instance", err)
		}
		if inst.State != provider.StateStopped || inst.ID != id {
			t.Errorf("Get during Delete = %+v, want Stopped %s", inst, id)
		}
		close(release)
		if err := <-done; err != nil {
			t.Fatalf("Delete() error = %v", err)
		}
		_, err = fx.p.Get(fx.ctx, id)
		assertProviderError(t, err, "get", provider.ErrNotFound)
	})
}

func TestGet_backendBusyIsTransientNeverNotFound(t *testing.T) {
	t.Parallel()
	tests := []struct {
		name string
		err  error
	}{
		{name: "operation invalid", err: fakeErr(libvirt.ErrOperationInvalid, "Requested operation is not valid: domain is being migrated")},
		{name: "call timed out", err: fmt.Errorf("%w: libvirt call DomainGetState on beelink exceeded its 30s budget: %w", provider.ErrTransient, context.DeadlineExceeded)},
		{name: "unknown libvirt code", err: fakeErr(libvirt.ErrInternalError, "internal error: qemu monitor unresponsive")},
		{name: "not a libvirt error", err: errors.New("read tcp: connection reset by peer")},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			fx := newFixture(t, 1)
			id := fx.create(testName)
			fx.fake.failWith("DomainGetState", tc.err)
			inst, err := fx.p.Get(fx.ctx, id)
			if inst != nil {
				t.Errorf("Get = %+v, want nil", inst)
			}
			assertProviderError(t, err, "get", provider.ErrTransient)
			if errors.Is(err, provider.ErrNotFound) {
				t.Errorf("Get error = %v, must never be NotFound", err)
			}
		})
	}
}

func TestGet_runningWithoutIPIsProvisioning(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	inst := fx.get(fx.create(testName))
	if inst.State != provider.StateProvisioning || inst.IP != "" {
		t.Errorf("Get = %+v, want Provisioning with no IP", inst)
	}
}

func TestGet_runningWithIPIsRunning(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	id := fx.create(testName)
	fx.setAddrs(testName, libvirt.DomainInterfaceAddressesSrcAgent, "127.0.0.1", "169.254.1.2", "10.0.0.5")
	inst := fx.get(id)
	if inst.State != provider.StateRunning || inst.IP != "10.0.0.5" {
		t.Errorf("Get = %+v, want Running with 10.0.0.5", inst)
	}
	if got := fx.logs.matching("kvm2 domain fetched"); len(got) != 1 || !strings.Contains(got[0], `"ip"="10.0.0.5"`) || !strings.Contains(got[0], `"state"="Running"`) {
		t.Errorf("fetched line = %v, want state and ip", got)
	}
}

func TestGet_agentPreferredOverARP(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	id := fx.create(testName)
	fx.setAddrs(testName, libvirt.DomainInterfaceAddressesSrcAgent, "10.0.0.5")
	fx.setAddrs(testName, libvirt.DomainInterfaceAddressesSrcArp, "10.0.0.6")
	before := fx.fake.callCount("DomainInterfaceAddresses")
	inst := fx.get(id)
	if inst.IP != "10.0.0.5" {
		t.Errorf("IP = %q, want the agent's 10.0.0.5", inst.IP)
	}
	if got := fx.fake.callCount("DomainInterfaceAddresses") - before; got != 1 {
		t.Errorf("DomainInterfaceAddresses calls = %d, want 1 (ARP not consulted)", got)
	}
}

func TestGet_arpFallbackWhenAgentFails(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 2)
	id := fx.create(testName)
	fx.setAddrs(testName, libvirt.DomainInterfaceAddressesSrcArp, "10.0.0.6")
	var calls int
	fx.fake.mu.Lock()
	fx.fake.hooks["DomainInterfaceAddresses"] = func() error {
		calls++
		if calls%2 == 1 {
			return fakeErr(libvirt.ErrAgentUnresponsive, "Guest agent is not responding")
		}
		return nil
	}
	fx.fake.mu.Unlock()
	inst := fx.get(id)
	if inst.State != provider.StateRunning || inst.IP != "10.0.0.6" {
		t.Errorf("Get = %+v, want Running with ARP's 10.0.0.6", inst)
	}
	if got := fx.logs.matching("no addresses from source"); len(got) != 1 || !strings.Contains(got[0], `"source"="agent"`) {
		t.Errorf("agent failure line = %v", got)
	}
}

func TestGet_addressErrorIsProvisioning(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	id := fx.create(testName)
	fx.fake.failWith("DomainInterfaceAddresses", fakeErr(libvirt.ErrAgentUnresponsive, "Guest agent is not responding"))
	inst := fx.get(id)
	if inst.State != provider.StateProvisioning || inst.IP != "" {
		t.Errorf("Get = %+v, want Provisioning with no IP", inst)
	}
}

func TestGet_readsUIDAndCreatedAtFromBackend(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	created := time.Date(2026, 9, 16, 12, 0, 0, 0, time.UTC)
	fx.p.now = func() time.Time { return created }
	id := fx.create(testName)
	inst := fx.get(id)
	if inst.UID != testUID || !inst.CreatedAt.Equal(created) {
		t.Errorf("Get = %+v, want uid %s created %s", inst, testUID, created)
	}

	later := created.Add(48 * time.Hour)
	fx.withDomain(testName, func(d *fakeDomain) { d.metadata = managedMetadata("rewritten-uid", later) })
	inst = fx.get(id)
	if inst.UID != "rewritten-uid" || !inst.CreatedAt.Equal(later) {
		t.Errorf("Get after metadata change = %+v, want uid rewritten-uid created %s (read back, not remembered)", inst, later)
	}
}

func TestGet_unmanagedDomainHasEmptyUID(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	fx.fake.addDomain("legacy-vm", libvirt.DomainRunning, "")
	inst := fx.get(formatProviderID(testHost, "legacy-vm"))
	if inst.UID != "" || !inst.CreatedAt.IsZero() || inst.State != provider.StateProvisioning {
		t.Errorf("Get = %+v, want empty uid, zero createdAt, Provisioning", inst)
	}
}

func TestGet_malformedIDIsPermanent(t *testing.T) {
	t.Parallel()
	ids := []string{"", "proxy-x", "beelink/proxy-x", "hosts/beelink/proxy-x", "hosts//domains/proxy-x", "hosts/beelink/domains/", "hosts/beelink/domains/a/b", "nodes/beelink/domains/proxy-x"}
	for _, id := range ids {
		t.Run(id, func(t *testing.T) {
			t.Parallel()
			fx := newFixture(t, 1)
			inst, err := fx.p.Get(fx.ctx, id)
			if inst != nil {
				t.Errorf("Get(%q) = %+v, want nil", id, inst)
			}
			assertProviderError(t, err, "get", provider.ErrPermanent)
			var pe *provider.Error
			if errors.As(err, &pe) && pe.ID != id {
				t.Errorf("error.ID = %q, want %q", pe.ID, id)
			}
			if got := fx.dialer.dials.Load(); got != 0 {
				t.Errorf("dials = %d, want 0", got)
			}
		})
	}
}

func TestGet_unconfiguredHostIsPermanent(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	_, err := fx.p.Get(fx.ctx, formatProviderID("nas9", testName))
	assertProviderError(t, err, "get", provider.ErrPermanent)
	if !strings.Contains(err.Error(), `"nas9"`) {
		t.Errorf("error = %v, want the host named", err)
	}
	if got := fx.dialer.dials.Load(); got != 0 {
		t.Errorf("dials = %d, want 0", got)
	}
}

func TestGet_unknownStateIsStopped(t *testing.T) {
	t.Parallel()
	fx := newFixture(t, 1)
	fx.fake.addDomain(testName, libvirt.DomainState(42), managedMetadata(testUID, time.Now()))
	inst := fx.get(formatProviderID(testHost, testName))
	if inst.State != provider.StateStopped {
		t.Errorf("State = %s, want Stopped for an unknown backend state", inst.State)
	}
}