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

type tenantPhaseResult struct {
	phase              databasev1alpha1.PostgreSQLTenantPhase
	reconcilingMessage string
}

type tenantPhaseHandler func(*databasev1alpha1.PostgreSQLTenant) tenantPhaseResult

type tenantStateMachine struct {
	handlers map[databasev1alpha1.PostgreSQLTenantPhase]tenantPhaseHandler
}

func newTenantStateMachine() tenantStateMachine {
	return tenantStateMachine{handlers: map[databasev1alpha1.PostgreSQLTenantPhase]tenantPhaseHandler{
		databasev1alpha1.PostgreSQLTenantPhasePending:               reconcileTenantPending,
		databasev1alpha1.PostgreSQLTenantPhasePlanned:               keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseCredentialCreated:     keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseRoleCreated:           keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseDatabaseCreated:       keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseExternalSecretCreated: keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseCredentialProjected:   keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseReady:                 keepTenantPhase,
		databasev1alpha1.PostgreSQLTenantPhaseDeleting:              reconcileTenantDeleting,
	}}
}

func (m tenantStateMachine) reconcile(tenant *databasev1alpha1.PostgreSQLTenant) tenantPhaseResult {
	phase := tenant.Status.Phase
	if !tenant.DeletionTimestamp.IsZero() {
		phase = databasev1alpha1.PostgreSQLTenantPhaseDeleting
	} else if phase == "" {
		phase = databasev1alpha1.PostgreSQLTenantPhasePending
	}

	handler, found := m.handlers[phase]
	if !found {
		return tenantPhaseResult{phase: phase}
	}
	return handler(tenant)
}

func reconcileTenantPending(*databasev1alpha1.PostgreSQLTenant) tenantPhaseResult {
	return tenantPhaseResult{
		phase:              databasev1alpha1.PostgreSQLTenantPhasePending,
		reconcilingMessage: "tenant is waiting for its instance",
	}
}

func reconcileTenantDeleting(*databasev1alpha1.PostgreSQLTenant) tenantPhaseResult {
	return tenantPhaseResult{
		phase:              databasev1alpha1.PostgreSQLTenantPhaseDeleting,
		reconcilingMessage: "tenant deletion is reconciling",
	}
}

func keepTenantPhase(tenant *databasev1alpha1.PostgreSQLTenant) tenantPhaseResult {
	return tenantPhaseResult{phase: tenant.Status.Phase}
}