/*
Copyright (c) 2017 OpenStack Foundation.

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 openstack

import (
	"fmt"
	"time"

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

	"github.com/golang/glog"
	"github.com/gophercloud/gophercloud"
	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/layer3/floatingips"
	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/listeners"
	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/loadbalancers"
	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/monitors"
	"github.com/gophercloud/gophercloud/openstack/networking/v2/extensions/lbaas_v2/pools"
	"github.com/gophercloud/gophercloud/pagination"
)

const (
	defaultMonitorDelay   = 10
	defaultMonitorRetry   = 3
	defaultMonotorTimeout = 3

	// loadbalancerActive* is configuration of exponential backoff for
	// going into ACTIVE loadbalancer provisioning status. Starting with 1
	// seconds, multiplying by 1.2 with each step and taking 19 steps at maximum
	// it will time out after 128s, which roughly corresponds to 120s
	loadbalancerActiveInitDealy = 1 * time.Second
	loadbalancerActiveFactor    = 1.2
	loadbalancerActiveSteps     = 19

	// loadbalancerDelete* is configuration of exponential backoff for
	// waiting for delete operation to complete. Starting with 1
	// seconds, multiplying by 1.2 with each step and taking 13 steps at maximum
	// it will time out after 32s, which roughly corresponds to 30s
	loadbalancerDeleteInitDealy = 1 * time.Second
	loadbalancerDeleteFactor    = 1.2
	loadbalancerDeleteSteps     = 13

	activeStatus = "ACTIVE"
	errorStatus  = "ERROR"
)

// LoadBalancer contains all essential information of kubernetes service.
type LoadBalancer struct {
	Name            string
	ServicePort     int
	TenantID        string
	SubnetID        string
	Protocol        string
	InternalIP      string
	ExternalIP      string
	SessionAffinity bool
	Endpoints       []Endpoint
}

// Endpoint represents a container endpoint.
type Endpoint struct {
	Address string
	Port    int
}

// LoadBalancerStatus contains the status of a load balancer.
type LoadBalancerStatus struct {
	InternalIP string
	ExternalIP string
}

// EnsureLoadBalancer ensures a load balancer is created.
func (os *Client) EnsureLoadBalancer(lb *LoadBalancer) (*LoadBalancerStatus, error) {
	// removes old one if already exists.
	loadbalancer, err := os.getLoadBalanceByName(lb.Name)
	if err != nil {
		if isNotFound(err) {
			// create a new one.
			lbOpts := loadbalancers.CreateOpts{
				Name:        lb.Name,
				Description: "Stackube service",
				VipSubnetID: lb.SubnetID,
				TenantID:    lb.TenantID,
			}
			loadbalancer, err = loadbalancers.Create(os.Network, lbOpts).Extract()
			if err != nil {
				glog.Errorf("Create load balancer %q failed: %v", lb.Name, err)
				return nil, err
			}
		}
	} else {
		glog.V(3).Infof("LoadBalancer %s already exists", lb.Name)
	}

	status, err := os.waitLoadBalancerStatus(loadbalancer.ID)
	if err != nil {
		glog.Errorf("Waiting for load balancer provision failed: %v", err)
		return nil, err
	}

	glog.V(3).Infof("Load balancer %q becomes %q", lb.Name, status)

	// get old listeners
	var listener *listeners.Listener
	oldListeners, err := os.getListenersByLoadBalancerID(loadbalancer.ID)
	if err != nil {
		return nil, fmt.Errorf("error getting LB %s listeners: %v", loadbalancer.Name, err)
	}
	for i := range oldListeners {
		l := oldListeners[i]
		if l.ProtocolPort == lb.ServicePort {
			listener = &l
		} else {
			// delete the obsolete listener
			if err := os.ensureListenerDeleted(loadbalancer.ID, l); err != nil {
				return nil, fmt.Errorf("error deleting listener %q: %v", l.Name, err)
			}
			os.waitLoadBalancerStatus(loadbalancer.ID)
		}
	}

	// create the listener.
	if listener == nil {
		lisOpts := listeners.CreateOpts{
			LoadbalancerID: loadbalancer.ID,
			// Only tcp is supported now.
			Protocol:     listeners.ProtocolTCP,
			ProtocolPort: lb.ServicePort,
			TenantID:     lb.TenantID,
			Name:         lb.Name,
		}
		listener, err = listeners.Create(os.Network, lisOpts).Extract()
		if err != nil {
			glog.Errorf("Create listener %q failed: %v", lb.Name, err)
			return nil, err
		}
		os.waitLoadBalancerStatus(loadbalancer.ID)
	}

	// create the load balancer pool.
	pool, err := os.getPoolByListenerID(loadbalancer.ID, listener.ID)
	if err != nil && !isNotFound(err) {
		return nil, fmt.Errorf("error getting pool for listener %q: %v", listener.ID, err)
	}
	if pool == nil {
		poolOpts := pools.CreateOpts{
			Name:       lb.Name,
			ListenerID: listener.ID,
			Protocol:   pools.ProtocolTCP,
			LBMethod:   pools.LBMethodRoundRobin,
			TenantID:   lb.TenantID,
		}
		if lb.SessionAffinity {
			poolOpts.Persistence = &pools.SessionPersistence{Type: "SOURCE_IP"}
		}
		pool, err = pools.Create(os.Network, poolOpts).Extract()
		if err != nil {
			glog.Errorf("Create pool %q failed: %v", lb.Name, err)
			return nil, err
		}
		os.waitLoadBalancerStatus(loadbalancer.ID)
	}

	// create load balancer members.
	members, err := os.getMembersByPoolID(pool.ID)
	if err != nil && !isNotFound(err) {
		return nil, fmt.Errorf("error getting members for pool %q: %v", pool.ID, err)
	}
	for _, ep := range lb.Endpoints {
		if !memberExists(members, ep.Address, ep.Port) {
			memberName := fmt.Sprintf("%s-%s-%d", lb.Name, ep.Address, ep.Port)
			_, err = pools.CreateMember(os.Network, pool.ID, pools.CreateMemberOpts{
				Name:         memberName,
				ProtocolPort: ep.Port,
				Address:      ep.Address,
				SubnetID:     lb.SubnetID,
			}).Extract()
			if err != nil {
				glog.Errorf("Create member %q failed: %v", memberName, err)
				return nil, err
			}
			os.waitLoadBalancerStatus(loadbalancer.ID)
		} else {
			members = popMember(members, ep.Address, ep.Port)
		}
	}
	// delete obsolete members
	for _, member := range members {
		glog.V(4).Infof("Deleting obsolete member %s for pool %s address %s", member.ID,
			pool.ID, member.Address)
		err := pools.DeleteMember(os.Network, pool.ID, member.ID).ExtractErr()
		if err != nil && !isNotFound(err) {
			return nil, fmt.Errorf("error deleting member %s for pool %s address %s: %v",
				member.ID, pool.ID, member.Address, err)
		}
	}

	// create loadbalancer monitor.
	if pool.MonitorID == "" {
		_, err = monitors.Create(os.Network, monitors.CreateOpts{
			Name:       lb.Name,
			Type:       monitors.TypeTCP,
			PoolID:     pool.ID,
			TenantID:   lb.TenantID,
			Delay:      defaultMonitorDelay,
			Timeout:    defaultMonotorTimeout,
			MaxRetries: defaultMonitorRetry,
		}).Extract()
		if err != nil {
			glog.Errorf("Create monitor for pool %q failed: %v", pool.ID, err)
			return nil, err
		}
	}

	// associate external IP for the vip.
	fip, err := os.associateFloatingIP(lb.TenantID, loadbalancer.VipPortID, lb.ExternalIP)
	if err != nil {
		glog.Errorf("associateFloatingIP for port %q failed: %v", loadbalancer.VipPortID, err)
		return nil, err
	}

	return &LoadBalancerStatus{
		InternalIP: loadbalancer.VipAddress,
		ExternalIP: fip,
	}, nil
}

// GetLoadBalancer gets a load balancer by name.
func (os *Client) GetLoadBalancer(name string) (*LoadBalancer, error) {
	// get load balancer
	lb, err := os.getLoadBalanceByName(name)
	if err != nil {
		return nil, err
	}

	// get listener
	listener, err := os.getListenerByName(name)
	if err != nil {
		return nil, err
	}

	// get members
	endpoints := make([]Endpoint, 0)
	for _, pool := range listener.Pools {
		for _, m := range pool.Members {
			endpoints = append(endpoints, Endpoint{
				Address: m.Address,
				Port:    m.ProtocolPort,
			})
		}
	}

	return &LoadBalancer{
		Name:            lb.Name,
		ServicePort:     listener.ProtocolPort,
		TenantID:        lb.TenantID,
		SubnetID:        lb.VipSubnetID,
		Protocol:        listener.Protocol,
		InternalIP:      lb.VipAddress,
		SessionAffinity: listener.Pools[0].Persistence.Type != "",
		Endpoints:       endpoints,
	}, nil
}

// LoadBalancerExist returns whether a load balancer has already been exist.
func (os *Client) LoadBalancerExist(name string) (bool, error) {
	_, err := os.getLoadBalanceByName(name)
	if err != nil {
		if isNotFound(err) {
			return false, nil
		}

		return false, err
	}

	return true, nil
}

// EnsureLoadBalancerDeleted ensures a load balancer is deleted.
func (os *Client) EnsureLoadBalancerDeleted(name string) error {
	// get load balancer
	lb, err := os.getLoadBalanceByName(name)
	if err != nil {
		if isNotFound(err) {
			return nil
		}

		return err
	}

	// delete floatingip
	floatingIP, err := os.getFloatingIPByPortID(lb.VipPortID)
	if err != nil && !isNotFound(err) {
		return fmt.Errorf("error getting floating ip by port %q: %v", lb.VipPortID, err)
	}
	if floatingIP != nil {
		err = floatingips.Delete(os.Network, floatingIP.ID).ExtractErr()
		if err != nil && !isNotFound(err) {
			return fmt.Errorf("error deleting floating ip %q: %v", floatingIP.ID, err)
		}
	}

	// get listeners and corelative pools and members
	var poolIDs []string
	var monitorIDs []string
	var memberIDs []string
	listenerList, err := os.getListenersByLoadBalancerID(lb.ID)
	if err != nil {
		return fmt.Errorf("Error getting load balancer %s listeners: %v", lb.ID, err)
	}

	for _, listener := range listenerList {
		pool, err := os.getPoolByListenerID(lb.ID, listener.ID)
		if err != nil && !isNotFound(err) {
			return fmt.Errorf("error getting pool for listener %s: %v", listener.ID, err)
		}
		poolIDs = append(poolIDs, pool.ID)
		if pool.MonitorID != "" {
			monitorIDs = append(monitorIDs, pool.MonitorID)
		}
	}
	for _, pool := range poolIDs {
		membersList, err := os.getMembersByPoolID(pool)
		if err != nil && !isNotFound(err) {
			return fmt.Errorf("Error getting pool members %s: %v", pool, err)
		}
		for _, member := range membersList {
			memberIDs = append(memberIDs, member.ID)
		}
	}

	// delete all monitors
	for _, monitorID := range monitorIDs {
		err := monitors.Delete(os.Network, monitorID).ExtractErr()
		if err != nil && !isNotFound(err) {
			return err
		}
		os.waitLoadBalancerStatus(lb.ID)
	}

	// delete all members and pools
	for _, poolID := range poolIDs {
		// delete all members for this pool
		for _, memberID := range memberIDs {
			err := pools.DeleteMember(os.Network, poolID, memberID).ExtractErr()
			if err != nil && !isNotFound(err) {
				return err
			}
			os.waitLoadBalancerStatus(lb.ID)
		}

		// delete pool
		err := pools.Delete(os.Network, poolID).ExtractErr()
		if err != nil && !isNotFound(err) {
			return err
		}
		os.waitLoadBalancerStatus(lb.ID)
	}

	// delete all listeners
	for _, listener := range listenerList {
		err := listeners.Delete(os.Network, listener.ID).ExtractErr()
		if err != nil && !isNotFound(err) {
			return err
		}
		os.waitLoadBalancerStatus(lb.ID)
	}

	// delete the load balancer
	err = loadbalancers.Delete(os.Network, lb.ID).ExtractErr()
	if err != nil && !isNotFound(err) {
		return err
	}
	os.waitLoadBalancerStatus(lb.ID)

	return nil
}

func (os *Client) ensureListenerDeleted(loadbalancerID string, listener listeners.Listener) error {
	for _, pool := range listener.Pools {
		for _, member := range pool.Members {
			// delete member
			if err := pools.DeleteMember(os.Network, pool.ID, member.ID).ExtractErr(); err != nil && !isNotFound(err) {
				return err
			}
			os.waitLoadBalancerStatus(loadbalancerID)
		}

		// delete monitor
		if err := monitors.Delete(os.Network, pool.MonitorID).ExtractErr(); err != nil && !isNotFound(err) {
			return err
		}
		os.waitLoadBalancerStatus(loadbalancerID)

		// delete pool
		if err := pools.Delete(os.Network, pool.ID).ExtractErr(); err != nil && !isNotFound(err) {
			return err
		}
		os.waitLoadBalancerStatus(loadbalancerID)
	}

	// delete listener
	if err := listeners.Delete(os.Network, listener.ID).ExtractErr(); err != nil && !isNotFound(err) {
		return err
	}
	os.waitLoadBalancerStatus(loadbalancerID)

	return nil
}

func (os *Client) waitLoadBalancerStatus(loadbalancerID string) (string, error) {
	backoff := wait.Backoff{
		Duration: loadbalancerActiveInitDealy,
		Factor:   loadbalancerActiveFactor,
		Steps:    loadbalancerActiveSteps,
	}

	var provisioningStatus string
	err := wait.ExponentialBackoff(backoff, func() (bool, error) {
		loadbalancer, err := loadbalancers.Get(os.Network, loadbalancerID).Extract()
		if err != nil {
			return false, err
		}
		provisioningStatus = loadbalancer.ProvisioningStatus
		if loadbalancer.ProvisioningStatus == activeStatus {
			return true, nil
		} else if loadbalancer.ProvisioningStatus == errorStatus {
			return true, fmt.Errorf("Loadbalancer has gone into ERROR state")
		} else {
			return false, nil
		}

	})

	if err == wait.ErrWaitTimeout {
		err = fmt.Errorf("Loadbalancer failed to go into ACTIVE provisioning status within alloted time")
	}
	return provisioningStatus, err
}

func (os *Client) waitLoadbalancerDeleted(loadbalancerID string) error {
	backoff := wait.Backoff{
		Duration: loadbalancerDeleteInitDealy,
		Factor:   loadbalancerDeleteFactor,
		Steps:    loadbalancerDeleteSteps,
	}
	err := wait.ExponentialBackoff(backoff, func() (bool, error) {
		_, err := loadbalancers.Get(os.Network, loadbalancerID).Extract()
		if err != nil {
			if err == ErrNotFound {
				return true, nil
			} else {
				return false, err
			}
		} else {
			return false, nil
		}
	})

	if err == wait.ErrWaitTimeout {
		err = fmt.Errorf("Loadbalancer failed to delete within the alloted time")
	}

	return err
}

func (os *Client) getListenersByLoadBalancerID(id string) ([]listeners.Listener, error) {
	var existingListeners []listeners.Listener
	err := listeners.List(os.Network, listeners.ListOpts{LoadbalancerID: id}).EachPage(func(page pagination.Page) (bool, error) {
		listenerList, err := listeners.ExtractListeners(page)
		if err != nil {
			return false, err
		}
		for _, l := range listenerList {
			for _, lb := range l.Loadbalancers {
				if lb.ID == id {
					existingListeners = append(existingListeners, l)
					break
				}
			}
		}

		return true, nil
	})
	if err != nil {
		return nil, err
	}

	return existingListeners, nil
}

func (os *Client) getLoadBalanceByName(name string) (*loadbalancers.LoadBalancer, error) {
	var lb *loadbalancers.LoadBalancer

	opts := loadbalancers.ListOpts{Name: name}
	pager := loadbalancers.List(os.Network, opts)
	err := pager.EachPage(func(page pagination.Page) (bool, error) {
		lbs, err := loadbalancers.ExtractLoadBalancers(page)
		if err != nil {
			return false, err
		}

		switch len(lbs) {
		case 0:
			return false, ErrNotFound
		case 1:
			lb = &lbs[0]
			return true, nil
		default:
			return false, ErrMultipleResults
		}
	})
	if err != nil {
		return nil, err
	}

	if lb == nil {
		return nil, ErrNotFound
	}

	return lb, nil
}

func (os *Client) getPoolByListenerID(loadbalancerID string, listenerID string) (*pools.Pool, error) {
	listenerPools := make([]pools.Pool, 0, 1)
	err := pools.List(os.Network, pools.ListOpts{LoadbalancerID: loadbalancerID}).EachPage(
		func(page pagination.Page) (bool, error) {
			poolsList, err := pools.ExtractPools(page)
			if err != nil {
				return false, err
			}
			for _, p := range poolsList {
				for _, l := range p.Listeners {
					if l.ID == listenerID {
						listenerPools = append(listenerPools, p)
					}
				}
			}
			if len(listenerPools) > 1 {
				return false, ErrMultipleResults
			}
			return true, nil
		})
	if err != nil {
		if isNotFound(err) {
			return nil, ErrNotFound
		}
		return nil, err
	}

	if len(listenerPools) == 0 {
		return nil, ErrNotFound
	} else if len(listenerPools) > 1 {
		return nil, ErrMultipleResults
	}

	return &listenerPools[0], nil
}

// getPoolByName gets openstack pool by name.
func (os *Client) getPoolByName(name string) (*pools.Pool, error) {
	var pool *pools.Pool

	opts := pools.ListOpts{Name: name}
	pager := pools.List(os.Network, opts)
	err := pager.EachPage(func(page pagination.Page) (bool, error) {
		ps, err := pools.ExtractPools(page)
		if err != nil {
			return false, err
		}

		switch len(ps) {
		case 0:
			return false, ErrNotFound
		case 1:
			pool = &ps[0]
			return true, nil
		default:
			return false, ErrMultipleResults
		}
	})
	if err != nil {
		return nil, err
	}

	if pool == nil {
		return nil, ErrNotFound
	}

	return pool, nil
}

func (os *Client) getListenerByName(name string) (*listeners.Listener, error) {
	var listener *listeners.Listener

	opts := listeners.ListOpts{Name: name}
	pager := listeners.List(os.Network, opts)
	err := pager.EachPage(func(page pagination.Page) (bool, error) {
		lists, err := listeners.ExtractListeners(page)
		if err != nil {
			return false, err
		}

		switch len(lists) {
		case 0:
			return false, ErrNotFound
		case 1:
			listener = &lists[0]
			return true, nil
		default:
			return false, ErrMultipleResults
		}
	})
	if err != nil {
		return nil, err
	}

	if listener == nil {
		return nil, ErrNotFound
	}

	return listener, nil
}

func (os *Client) getMembersByPoolID(id string) ([]pools.Member, error) {
	var members []pools.Member
	err := pools.ListMembers(os.Network, id, pools.ListMembersOpts{}).EachPage(func(page pagination.Page) (bool, error) {
		membersList, err := pools.ExtractMembers(page)
		if err != nil {
			return false, err
		}
		members = append(members, membersList...)

		return true, nil
	})
	if err != nil {
		return nil, err
	}

	return members, nil
}

func (os *Client) getFloatingIPByPortID(portID string) (*floatingips.FloatingIP, error) {
	opts := floatingips.ListOpts{
		PortID: portID,
	}
	pager := floatingips.List(os.Network, opts)

	floatingIPList := make([]floatingips.FloatingIP, 0, 1)

	err := pager.EachPage(func(page pagination.Page) (bool, error) {
		f, err := floatingips.ExtractFloatingIPs(page)
		if err != nil {
			return false, err
		}
		floatingIPList = append(floatingIPList, f...)
		if len(floatingIPList) > 1 {
			return false, ErrMultipleResults
		}
		return true, nil
	})
	if err != nil {
		if isNotFound(err) {
			return nil, ErrNotFound
		}
		return nil, err
	}

	if len(floatingIPList) == 0 {
		return nil, ErrNotFound
	} else if len(floatingIPList) > 1 {
		return nil, ErrMultipleResults
	}

	return &floatingIPList[0], nil
}

// Check if a member exists for node
func memberExists(members []pools.Member, addr string, port int) bool {
	for _, member := range members {
		if member.Address == addr && member.ProtocolPort == port {
			return true
		}
	}

	return false
}

func (os *Client) associateFloatingIP(tenantID, portID, floatingIPAddress string) (string, error) {
	var fip *floatingips.FloatingIP
	opts := floatingips.ListOpts{FloatingIP: floatingIPAddress}
	pager := floatingips.List(os.Network, opts)
	err := pager.EachPage(func(page pagination.Page) (bool, error) {
		floatingipList, err := floatingips.ExtractFloatingIPs(page)
		if err != nil {
			return false, err
		}

		if len(floatingipList) > 0 {
			fip = &floatingipList[0]
		}

		return true, nil
	})
	if err != nil {
		return "", err
	}

	if fip != nil {
		if fip.PortID != "" {
			if fip.PortID == portID {
				glog.V(3).Infof("FIP %q has already been associated with port %q", floatingIPAddress, portID)
				return fip.FloatingIP, nil
			}
			// fip has already been used
			return fip.FloatingIP, fmt.Errorf("FloatingIP %v is already been binded to %v", floatingIPAddress, fip.PortID)
		}

		// Update floatingip
		floatOpts := floatingips.UpdateOpts{PortID: &portID}
		_, err = floatingips.Update(os.Network, fip.ID, floatOpts).Extract()
		if err != nil {
			glog.Errorf("Bind floatingip %v to %v failed: %v", floatingIPAddress, portID, err)
			return "", err
		}
	} else {
		// Create floatingip
		opts := floatingips.CreateOpts{
			FloatingNetworkID: os.ExtNetID,
			TenantID:          tenantID,
			FloatingIP:        floatingIPAddress,
			PortID:            portID,
		}
		fip, err = floatingips.Create(os.Network, opts).Extract()
		if err != nil {
			glog.Errorf("Create floatingip failed: %v", err)
			return "", err
		}
	}

	return fip.FloatingIP, nil
}

func popMember(members []pools.Member, addr string, port int) []pools.Member {
	for i, member := range members {
		if member.Address == addr && member.ProtocolPort == port {
			members[i] = members[len(members)-1]
			members = members[:len(members)-1]
		}
	}

	return members
}

func isNotFound(err error) bool {
	if err == ErrNotFound {
		return true
	}

	if _, ok := err.(*gophercloud.ErrResourceNotFound); ok {
		return true
	}

	if _, ok := err.(*gophercloud.ErrDefault404); ok {
		return true
	}

	return false
}