/*
   Copyright 2014 CoreOS, Inc.

   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 etcdserver

import (
	"crypto/sha1"
	"encoding/binary"
	"fmt"
	"math/rand"
	"net/url"
	"sort"
	"strings"

	"github.com/coreos/etcd/pkg/flags"
	"github.com/coreos/etcd/pkg/types"
)

// Cluster is a list of Members that belong to the same raft cluster
type Cluster struct {
	id      uint64
	name    string
	members map[uint64]*Member
}

func NewCluster(clusterName string) *Cluster {
	c := &Cluster{name: clusterName, members: make(map[uint64]*Member)}
	return c
}

func (c Cluster) FindName(name string) *Member {
	for _, m := range c.members {
		if m.Name == name {
			return m
		}
	}
	return nil
}

func (c Cluster) FindID(id uint64) *Member {
	return c.members[id]
}

func (c Cluster) Add(m Member) error {
	if c.FindID(m.ID) != nil {
		return fmt.Errorf("Member exists with identical ID %v", m)
	}
	c.members[m.ID] = &m
	return nil
}

func (c *Cluster) AddSlice(mems []Member) error {
	for _, m := range mems {
		err := c.Add(m)
		if err != nil {
			return err
		}
	}

	return nil
}

// Pick chooses a random address from a given Member's addresses, and returns it as
// an addressible URI. If the given member does not exist, an empty string is returned.
func (c Cluster) Pick(id uint64) string {
	if m := c.FindID(id); m != nil {
		urls := m.PeerURLs
		if len(urls) == 0 {
			return ""
		}
		return urls[rand.Intn(len(urls))]
	}

	return ""
}

// AddMembersFromFlag parses a sets of names to IPs either from the command line or discovery formatted like:
// mach0=http://1.1.1.1,mach0=http://2.2.2.2,mach0=http://1.1.1.1,mach1=http://2.2.2.2,mach1=http://3.3.3.3
func (c *Cluster) SetMembersFromString(s string) error {
	c.members = make(map[uint64]*Member)
	v, err := url.ParseQuery(strings.Replace(s, ",", "&", -1))
	if err != nil {
		return err
	}

	for name, urls := range v {
		if len(urls) == 0 || urls[0] == "" {
			return fmt.Errorf("Empty URL given for %q", name)
		}

		m := newMember(name, types.URLs(*flags.NewURLsValue(strings.Join(urls, ","))), c.name, nil)
		err := c.Add(*m)
		if err != nil {
			return err
		}
	}
	return nil
}

func (c *Cluster) AddMemberFromURLs(name string, urls types.URLs) (*Member, error) {
	m := newMember(name, urls, c.name, nil)
	err := c.Add(*m)
	if err != nil {
		return nil, err
	}
	return m, nil
}

func (c *Cluster) GenID(salt []byte) {
	mIDs := c.MemberIDs()
	b := make([]byte, 8*len(mIDs))
	for i, id := range mIDs {
		binary.BigEndian.PutUint64(b[8*i:], id)
	}
	b = append(b, salt...)
	hash := sha1.Sum(b)
	c.id = binary.BigEndian.Uint64(hash[:8])
}

func (c Cluster) String() string {
	sl := []string{}
	for _, m := range c.members {
		for _, u := range m.PeerURLs {
			sl = append(sl, fmt.Sprintf("%s=%s", m.Name, u))
		}
	}
	sort.Strings(sl)
	return strings.Join(sl, ",")
}

func (c Cluster) ID() uint64 { return c.id }

func (c Cluster) Members() map[uint64]*Member { return c.members }

func (c Cluster) MemberIDs() []uint64 {
	var ids []uint64
	for _, m := range c.members {
		ids = append(ids, m.ID)
	}
	sort.Sort(types.Uint64Slice(ids))
	return ids
}

// PeerURLs returns a list of all peer addresses. Each address is prefixed
// with the scheme (currently "http://"). The returned list is sorted in
// ascending lexicographical order.
func (c Cluster) PeerURLs() []string {
	endpoints := make([]string, 0)
	for _, p := range c.members {
		for _, addr := range p.PeerURLs {
			endpoints = append(endpoints, addr)
		}
	}
	sort.Strings(endpoints)
	return endpoints
}

// ClientURLs returns a list of all client addresses. Each address is prefixed
// with the scheme (currently "http://"). The returned list is sorted in
// ascending lexicographical order.
func (c Cluster) ClientURLs() []string {
	urls := make([]string, 0)
	for _, p := range c.members {
		for _, url := range p.ClientURLs {
			urls = append(urls, url)
		}
	}
	sort.Strings(urls)
	return urls
}