/*
Copyright 2026.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package controller

import (
	"context"
	"errors"
	"time"

	. "github.com/onsi/ginkgo/v2"
	. "github.com/onsi/gomega"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	databasev1alpha1 "git.ddupan.top/panxiao81/postgresql-tenant-operator/api/v1alpha1"
)

type fakeInstanceInitializer struct {
	validateVersion string
	registryVersion string
	err             error
}

const testPostgreSQLVersion = "17.6"

func (f fakeInstanceInitializer) Validate(context.Context, *databasev1alpha1.PostgreSQLInstance) (string, error) {
	return f.validateVersion, f.err
}

func (f fakeInstanceInitializer) InitializeRegistry(context.Context, *databasev1alpha1.PostgreSQLInstance) (string, error) {
	return f.registryVersion, f.err
}

var _ = Describe("phase handler state machines", func() {
	It("persists validation intent before touching unavailable dependencies", func() {
		instance := &databasev1alpha1.PostgreSQLInstance{}
		machine := newInstanceStateMachine(fakeInstanceInitializer{err: errors.New("must not be called")})
		result, err := machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(result.RequeueAfter).To(BeNumerically(">", 0))
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseValidating))
		Expect(instance.Status.Conditions[0].Status).To(Equal(metav1.ConditionUnknown))
	})

	It("persists a new validation checkpoint when a Ready Instance generation changes", func() {
		instance := &databasev1alpha1.PostgreSQLInstance{
			ObjectMeta: metav1.ObjectMeta{Generation: 4},
			Status: databasev1alpha1.PostgreSQLInstanceStatus{
				Phase: databasev1alpha1.PostgreSQLInstancePhaseReady, ObservedGeneration: 3,
			},
		}
		machine := newInstanceStateMachine(fakeInstanceInitializer{err: errors.New("must not be called")})
		_, err := machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseValidating))
		Expect(instance.Status.ObservedGeneration).To(Equal(int64(3)))
	})

	It("detects a dependency outage after Ready and recovers through registry initialization", func() {
		instance := &databasev1alpha1.PostgreSQLInstance{
			ObjectMeta: metav1.ObjectMeta{Generation: 3},
			Status: databasev1alpha1.PostgreSQLInstanceStatus{
				Phase: databasev1alpha1.PostgreSQLInstancePhaseReady, ObservedGeneration: 3,
			},
		}
		machine := newInstanceStateMachine(fakeInstanceInitializer{err: errors.New("unavailable")})
		_, err := machine.reconcile(context.Background(), instance)
		Expect(err).To(MatchError("unavailable"))
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseValidating))
		Expect(instance.Status.Conditions[0].Status).To(Equal(metav1.ConditionFalse))
		machine.initializer = fakeInstanceInitializer{
			validateVersion: testPostgreSQLVersion,
			registryVersion: testPostgreSQLVersion,
		}
		_, err = machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseInitializingRegistry))
		_, err = machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(instance.Status.Conditions[0].Status).To(Equal(metav1.ConditionTrue))
		result, err := machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseReady))
		Expect(result.RequeueAfter).To(Equal(time.Minute))
	})

	It("advances an Instance through external validation and registry initialization", func() {
		instance := &databasev1alpha1.PostgreSQLInstance{
			ObjectMeta: metav1.ObjectMeta{Generation: 3},
			Status:     databasev1alpha1.PostgreSQLInstanceStatus{Phase: databasev1alpha1.PostgreSQLInstancePhaseValidating},
		}
		machine := newInstanceStateMachine(fakeInstanceInitializer{
			validateVersion: testPostgreSQLVersion,
			registryVersion: testPostgreSQLVersion,
		})
		_, err := machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseInitializingRegistry))
		_, err = machine.reconcile(context.Background(), instance)
		Expect(err).NotTo(HaveOccurred())
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseReady))
		Expect(instance.Status.PostgreSQLVersion).To(Equal(testPostgreSQLVersion))
		Expect(instance.Status.ObservedGeneration).To(Equal(int64(3)))
		Expect(instance.Status.Conditions).To(ConsistOf(And(
			HaveField("Status", metav1.ConditionTrue), HaveField("Reason", databasev1alpha1.ReasonReady),
		)))
	})

	It("keeps the safe phase when a dependency is unavailable", func() {
		instance := &databasev1alpha1.PostgreSQLInstance{
			ObjectMeta: metav1.ObjectMeta{Generation: 2},
			Status:     databasev1alpha1.PostgreSQLInstanceStatus{Phase: databasev1alpha1.PostgreSQLInstancePhaseValidating},
		}
		machine := newInstanceStateMachine(fakeInstanceInitializer{err: errors.New("unavailable")})
		_, err := machine.reconcile(context.Background(), instance)
		Expect(err).To(MatchError("unavailable"))
		Expect(instance.Status.Phase).To(Equal(databasev1alpha1.PostgreSQLInstancePhaseValidating))
		Expect(instance.Status.Conditions).To(ConsistOf(And(
			HaveField("Status", metav1.ConditionFalse), HaveField("Reason", databasev1alpha1.ReasonDependencyUnavailable),
		)))
	})

	DescribeTable("dispatches Instance phases",
		func(instance *databasev1alpha1.PostgreSQLInstance, expected databasev1alpha1.PostgreSQLInstancePhase, hasMessage bool) {
			_, err := newInstanceStateMachine(nil).reconcile(context.Background(), instance)
			Expect(err).NotTo(HaveOccurred())
			Expect(instance.Status.Phase).To(Equal(expected))
			if hasMessage {
				Expect(instance.Status.Conditions).NotTo(BeEmpty())
			} else {
				Expect(instance.Status.Conditions).To(BeEmpty())
			}
		},
		Entry("starts validation from an empty checkpoint",
			&databasev1alpha1.PostgreSQLInstance{},
			databasev1alpha1.PostgreSQLInstancePhaseValidating,
			true,
		),
		Entry("keeps an active phase until its handler can observe dependencies",
			&databasev1alpha1.PostgreSQLInstance{Status: databasev1alpha1.PostgreSQLInstanceStatus{
				Phase: databasev1alpha1.PostgreSQLInstancePhaseInitializingRegistry,
			}},
			databasev1alpha1.PostgreSQLInstancePhaseInitializingRegistry,
			false,
		),
		Entry("routes deletion independently of the previous phase",
			deletingInstance(),
			databasev1alpha1.PostgreSQLInstancePhaseDeleting,
			true,
		),
	)

	DescribeTable("dispatches Tenant phases",
		func(tenant *databasev1alpha1.PostgreSQLTenant, expected databasev1alpha1.PostgreSQLTenantPhase, hasMessage bool) {
			result := newTenantStateMachine().reconcile(tenant)
			Expect(result.phase).To(Equal(expected))
			if hasMessage {
				Expect(result.reconcilingMessage).NotTo(BeEmpty())
			} else {
				Expect(result.reconcilingMessage).To(BeEmpty())
			}
		},
		Entry("starts pending from an empty checkpoint",
			&databasev1alpha1.PostgreSQLTenant{},
			databasev1alpha1.PostgreSQLTenantPhasePending,
			true,
		),
		Entry("keeps an active phase until its handler can observe dependencies",
			&databasev1alpha1.PostgreSQLTenant{Status: databasev1alpha1.PostgreSQLTenantStatus{
				Phase: databasev1alpha1.PostgreSQLTenantPhaseCredentialCreated,
			}},
			databasev1alpha1.PostgreSQLTenantPhaseCredentialCreated,
			false,
		),
		Entry("routes deletion independently of the previous phase",
			deletingTenant(),
			databasev1alpha1.PostgreSQLTenantPhaseDeleting,
			true,
		),
	)
})

func deletingInstance() *databasev1alpha1.PostgreSQLInstance {
	deletionTimestamp := metav1.NewTime(time.Now())
	return &databasev1alpha1.PostgreSQLInstance{
		ObjectMeta: metav1.ObjectMeta{DeletionTimestamp: &deletionTimestamp},
		Status: databasev1alpha1.PostgreSQLInstanceStatus{
			Phase: databasev1alpha1.PostgreSQLInstancePhaseReady,
		},
	}
}

func deletingTenant() *databasev1alpha1.PostgreSQLTenant {
	deletionTimestamp := metav1.NewTime(time.Now())
	return &databasev1alpha1.PostgreSQLTenant{
		ObjectMeta: metav1.ObjectMeta{DeletionTimestamp: &deletionTimestamp},
		Status: databasev1alpha1.PostgreSQLTenantStatus{
			Phase: databasev1alpha1.PostgreSQLTenantPhaseReady,
		},
	}
}