package consul

import (
	"encoding/binary"
	"fmt"
	"net"
	"runtime"
	"strconv"
	"strings"

	"github.com/hashicorp/consul/agent/metadata"
	"github.com/hashicorp/consul/agent/structs"
	"github.com/hashicorp/go-version"
	"github.com/hashicorp/hil"
	"github.com/hashicorp/hil/ast"
	"github.com/hashicorp/serf/serf"
)

/*
 * Contains an entry for each private block:
 * 10.0.0.0/8
 * 100.64.0.0/10
 * 127.0.0.0/8
 * 169.254.0.0/16
 * 172.16.0.0/12
 * 192.168.0.0/16
 */
var privateBlocks []*net.IPNet

func init() {
	// Add each private block
	privateBlocks = make([]*net.IPNet, 6)

	_, block, err := net.ParseCIDR("10.0.0.0/8")
	if err != nil {
		panic(fmt.Sprintf("Bad cidr. Got %v", err))
	}
	privateBlocks[0] = block

	_, block, err = net.ParseCIDR("100.64.0.0/10")
	if err != nil {
		panic(fmt.Sprintf("Bad cidr. Got %v", err))
	}
	privateBlocks[1] = block

	_, block, err = net.ParseCIDR("127.0.0.0/8")
	if err != nil {
		panic(fmt.Sprintf("Bad cidr. Got %v", err))
	}
	privateBlocks[2] = block

	_, block, err = net.ParseCIDR("169.254.0.0/16")
	if err != nil {
		panic(fmt.Sprintf("Bad cidr. Got %v", err))
	}
	privateBlocks[3] = block

	_, block, err = net.ParseCIDR("172.16.0.0/12")
	if err != nil {
		panic(fmt.Sprintf("Bad cidr. Got %v", err))
	}
	privateBlocks[4] = block

	_, block, err = net.ParseCIDR("192.168.0.0/16")
	if err != nil {
		panic(fmt.Sprintf("Bad cidr. Got %v", err))
	}
	privateBlocks[5] = block
}

// CanServersUnderstandProtocol checks to see if all the servers in the given
// list understand the given protocol version. If there are no servers in the
// list then this will return false.
func CanServersUnderstandProtocol(members []serf.Member, version uint8) (bool, error) {
	numServers, numWhoGrok := 0, 0
	for _, m := range members {
		if m.Tags["role"] != "consul" {
			continue
		}
		numServers++

		vsnMin, err := strconv.Atoi(m.Tags["vsn_min"])
		if err != nil {
			return false, err
		}

		vsnMax, err := strconv.Atoi(m.Tags["vsn_max"])
		if err != nil {
			return false, err
		}

		v := int(version)
		if (v >= vsnMin) && (v <= vsnMax) {
			numWhoGrok++
		}
	}
	return (numServers > 0) && (numWhoGrok == numServers), nil
}

// Returns if a member is a consul node. Returns a bool,
// and the datacenter.
func isConsulNode(m serf.Member) (bool, string) {
	if m.Tags["role"] != "node" {
		return false, ""
	}
	return true, m.Tags["dc"]
}

// Returns if the given IP is in a private block
func isPrivateIP(ipStr string) bool {
	ip := net.ParseIP(ipStr)
	for _, priv := range privateBlocks {
		if priv.Contains(ip) {
			return true
		}
	}
	return false
}

// Returns addresses from interfaces that is up
func activeInterfaceAddresses() ([]net.Addr, error) {
	var upAddrs []net.Addr
	var loAddrs []net.Addr

	interfaces, err := net.Interfaces()
	if err != nil {
		return nil, fmt.Errorf("Failed to get interfaces: %v", err)
	}

	for _, iface := range interfaces {
		// Require interface to be up
		if iface.Flags&net.FlagUp == 0 {
			continue
		}

		addresses, err := iface.Addrs()
		if err != nil {
			return nil, fmt.Errorf("Failed to get interface addresses: %v", err)
		}

		if iface.Flags&net.FlagLoopback != 0 {
			loAddrs = append(loAddrs, addresses...)
			continue
		}

		upAddrs = append(upAddrs, addresses...)
	}

	if len(upAddrs) == 0 {
		return loAddrs, nil
	}

	return upAddrs, nil
}

// GetPrivateIP is used to return the first private IP address
// associated with an interface on the machine
func GetPrivateIP() (net.IP, error) {
	addresses, err := activeInterfaceAddresses()
	if err != nil {
		return nil, fmt.Errorf("Failed to get interface addresses: %v", err)
	}

	return getPrivateIP(addresses)
}

func getPrivateIP(addresses []net.Addr) (net.IP, error) {
	var candidates []net.IP

	// Find private IPv4 address
	for _, rawAddr := range addresses {
		var ip net.IP
		switch addr := rawAddr.(type) {
		case *net.IPAddr:
			ip = addr.IP
		case *net.IPNet:
			ip = addr.IP
		default:
			continue
		}

		if ip.To4() == nil {
			continue
		}
		if !isPrivateIP(ip.String()) {
			continue
		}
		candidates = append(candidates, ip)
	}
	numIps := len(candidates)
	switch numIps {
	case 0:
		return nil, fmt.Errorf("No private IP address found")
	case 1:
		return candidates[0], nil
	default:
		return nil, fmt.Errorf("Multiple private IPs found. Please configure one.")
	}

}

// GetPublicIPv6 is used to return the first public IP address
// associated with an interface on the machine
func GetPublicIPv6() (net.IP, error) {
	addresses, err := net.InterfaceAddrs()
	if err != nil {
		return nil, fmt.Errorf("Failed to get interface addresses: %v", err)
	}

	return getPublicIPv6(addresses)
}

func isUniqueLocalAddress(ip net.IP) bool {
	return len(ip) == net.IPv6len && ip[0] == 0xfc && ip[1] == 0x00
}

func getPublicIPv6(addresses []net.Addr) (net.IP, error) {
	var candidates []net.IP

	// Find public IPv6 address
	for _, rawAddr := range addresses {
		var ip net.IP
		switch addr := rawAddr.(type) {
		case *net.IPAddr:
			ip = addr.IP
		case *net.IPNet:
			ip = addr.IP
		default:
			continue
		}

		if ip.To4() != nil {
			continue
		}

		if ip.IsLinkLocalUnicast() || isUniqueLocalAddress(ip) || ip.IsLoopback() {
			continue
		}
		candidates = append(candidates, ip)
	}
	numIps := len(candidates)
	switch numIps {
	case 0:
		return nil, fmt.Errorf("No public IPv6 address found")
	case 1:
		return candidates[0], nil
	default:
		return nil, fmt.Errorf("Multiple public IPv6 addresses found. Please configure one.")
	}
}

// Converts bytes to an integer
func bytesToUint64(b []byte) uint64 {
	return binary.BigEndian.Uint64(b)
}

// Converts a uint to a byte slice
func uint64ToBytes(u uint64) []byte {
	buf := make([]byte, 8)
	binary.BigEndian.PutUint64(buf, u)
	return buf
}

// runtimeStats is used to return various runtime information
func runtimeStats() map[string]string {
	return map[string]string{
		"os":         runtime.GOOS,
		"arch":       runtime.GOARCH,
		"version":    runtime.Version(),
		"max_procs":  strconv.FormatInt(int64(runtime.GOMAXPROCS(0)), 10),
		"goroutines": strconv.FormatInt(int64(runtime.NumGoroutine()), 10),
		"cpu_count":  strconv.FormatInt(int64(runtime.NumCPU()), 10),
	}
}

// ServersMeetMinimumVersion returns whether the given alive servers are at least on the
// given Consul version
func ServersMeetMinimumVersion(members []serf.Member, minVersion *version.Version) bool {
	return ServersMeetRequirements(members, func(srv *metadata.Server) bool {
		return srv.Status != serf.StatusAlive || !srv.Build.LessThan(minVersion)
	})
}

// ServersMeetMinimumVersion returns whether the given alive servers from a particular
// datacenter are at least on the given Consul version. This requires at least 1 alive server in the DC
func ServersInDCMeetMinimumVersion(members []serf.Member, datacenter string, minVersion *version.Version) (bool, bool) {
	found := false
	ok := ServersMeetRequirements(members, func(srv *metadata.Server) bool {
		if srv.Status != serf.StatusAlive || srv.Datacenter != datacenter {
			return true
		}

		found = true
		return !srv.Build.LessThan(minVersion)
	})

	return ok, found
}

// ServersMeetRequirements returns whether the given server members meet the requirements as defined by the
// callback function
func ServersMeetRequirements(members []serf.Member, meetsRequirements func(*metadata.Server) bool) bool {
	for _, member := range members {
		if valid, parts := metadata.IsConsulServer(member); valid {
			if !meetsRequirements(parts) {
				return false
			}
		}
	}

	return true
}

func ServersGetACLMode(members []serf.Member, leader string, datacenter string) (numServers int, mode structs.ACLMode, leaderMode structs.ACLMode) {
	numServers = 0
	mode = structs.ACLModeEnabled
	leaderMode = structs.ACLModeUnknown
	for _, member := range members {
		if valid, parts := metadata.IsConsulServer(member); valid {

			if datacenter != "" && parts.Datacenter != datacenter {
				continue
			}

			if parts.Status != serf.StatusAlive && parts.Status != serf.StatusFailed {
				// ignore any server that isn't alive or failed. We are considering failed
				// because in this state there is a reasonable expectation that they could
				// become stable again. Also autopilot should remove dead servers if they
				// are truly gone.
				continue
			}

			numServers += 1

			if memberAddr := (&net.TCPAddr{IP: member.Addr, Port: parts.Port}).String(); memberAddr == leader {
				leaderMode = parts.ACLs
			}

			switch parts.ACLs {
			case structs.ACLModeDisabled:
				// anything disabled means we cant enable ACLs
				mode = structs.ACLModeDisabled
			case structs.ACLModeEnabled:
				// do nothing
			case structs.ACLModeLegacy:
				// This covers legacy mode and older server versions that don't advertise ACL support
				if mode != structs.ACLModeDisabled && mode != structs.ACLModeUnknown {
					mode = structs.ACLModeLegacy
				}
			default:
				if mode != structs.ACLModeDisabled {
					mode = structs.ACLModeUnknown
				}
			}
		}
	}

	return
}

// InterpolateHIL processes the string as if it were HIL and interpolates only
// the provided string->string map as possible variables.
func InterpolateHIL(s string, vars map[string]string) (string, error) {
	if strings.Index(s, "${") == -1 {
		// Skip going to the trouble of parsing something that has no HIL.
		return s, nil
	}

	tree, err := hil.Parse(s)
	if err != nil {
		return "", err
	}

	vm := make(map[string]ast.Variable)
	for k, v := range vars {
		vm[k] = ast.Variable{
			Type:  ast.TypeString,
			Value: v,
		}
	}

	config := &hil.EvalConfig{
		GlobalScope: &ast.BasicScope{
			VarMap: vm,
		},
	}

	result, err := hil.Eval(tree, config)
	if err != nil {
		return "", err
	}

	if result.Type != hil.TypeString {
		return "", fmt.Errorf("generated unexpected hil type: %s", result.Type)
	}

	return result.Value.(string), nil
}