// Copyright 2020 Antrea Authors
//
// 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 types

import (
	"fmt"
	"sync"

	"k8s.io/apimachinery/pkg/util/sets"

	"antrea.io/antrea/pkg/agent/openflow"
	binding "antrea.io/antrea/pkg/ovs/openflow"
	k8sproxy "antrea.io/antrea/third_party/proxy"
)

// GroupCounter generates and manages global unique group ID.
type GroupCounter interface {
	// AllocateIfNotExist generates a global unique group ID for a Service if the group ID has not been generated, then
	// return the group ID (newly allocated or already allocated).
	AllocateIfNotExist(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) binding.GroupIDType
	// Get gets the group ID for the Service.
	Get(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) (binding.GroupIDType, bool)
	// Recycle removes the Service group ID mapping. The recycled group ID can be reused.
	Recycle(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) bool
	// GetAllGroupIDs gets all group IDs related to the Service.
	GetAllGroupIDs(svcNamespacedName string) []binding.GroupIDType
}

type groupCounter struct {
	mu             sync.Mutex
	groupAllocator openflow.GroupAllocator
	groupIDUpdates chan<- string

	servicePortNamesMap map[string]sets.Set[string]
	groupMap            map[string]binding.GroupIDType
}

func NewGroupCounter(groupAllocator openflow.GroupAllocator, groupIDUpdates chan<- string) *groupCounter {
	return &groupCounter{groupMap: map[string]binding.GroupIDType{}, groupAllocator: groupAllocator, groupIDUpdates: groupIDUpdates, servicePortNamesMap: map[string]sets.Set[string]{}}
}

func keyString(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) string {
	key := svcPortName.String()
	if isEndpointsLocal {
		key = fmt.Sprintf("%s/local", key)
	}
	return key
}

func (c *groupCounter) updateServicePortNameMap(svcNamespacedName string, svcKeyString string) {
	if _, ok := c.servicePortNamesMap[svcNamespacedName]; ok {
		c.servicePortNamesMap[svcNamespacedName].Insert(svcKeyString)
	} else {
		keyStringSet := sets.New[string](svcKeyString)
		c.servicePortNamesMap[svcNamespacedName] = keyStringSet
	}
}

func (c *groupCounter) deleteServicePortNameMap(svcNamespacedName string, svcKeyString string) {
	keyStringSet, ok := c.servicePortNamesMap[svcNamespacedName]
	if !ok {
		return
	}
	keyStringSet.Delete(svcKeyString)
	if keyStringSet.Len() == 0 {
		delete(c.servicePortNamesMap, svcNamespacedName)
	}
}

func (c *groupCounter) AllocateIfNotExist(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) binding.GroupIDType {
	c.mu.Lock()
	defer c.mu.Unlock()
	key := keyString(svcPortName, isEndpointsLocal)
	if id, ok := c.groupMap[key]; ok {
		return id
	}
	id := c.groupAllocator.Allocate()
	c.groupMap[key] = id
	c.updateServicePortNameMap(svcPortName.NamespacedName.String(), key)
	c.groupIDUpdates <- svcPortName.NamespacedName.String()
	return id
}

func (c *groupCounter) Get(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) (binding.GroupIDType, bool) {
	c.mu.Lock()
	defer c.mu.Unlock()
	key := keyString(svcPortName, isEndpointsLocal)
	id, exist := c.groupMap[key]
	return id, exist
}

func (c *groupCounter) Recycle(svcPortName k8sproxy.ServicePortName, isEndpointsLocal bool) bool {
	c.mu.Lock()
	defer c.mu.Unlock()

	key := keyString(svcPortName, isEndpointsLocal)
	if id, ok := c.groupMap[key]; ok {
		delete(c.groupMap, key)
		c.groupAllocator.Release(id)
		c.deleteServicePortNameMap(svcPortName.NamespacedName.String(), key)
		c.groupIDUpdates <- svcPortName.NamespacedName.String()
		return true
	}
	return false
}

func (c *groupCounter) GetAllGroupIDs(svcNamespacedName string) []binding.GroupIDType {
	c.mu.Lock()
	defer c.mu.Unlock()
	var ids []binding.GroupIDType
	for _, key := range c.servicePortNamesMap[svcNamespacedName].UnsortedList() {
		if id, ok := c.groupMap[key]; ok {
			ids = append(ids, id)
		}
	}
	return ids
}
