package gocql

import (
	"context"
	"errors"
	"fmt"
	"net"
	"strconv"
	"strings"
	"sync"
	"time"
)

type nodeState int32

func (n nodeState) String() string {
	if n == NodeUp {
		return "UP"
	} else if n == NodeDown {
		return "DOWN"
	}
	return fmt.Sprintf("UNKNOWN_%d", n)
}

const (
	NodeUp nodeState = iota
	NodeDown
)

type cassVersion struct {
	Major, Minor, Patch int
}

func (c *cassVersion) Set(v string) error {
	if v == "" {
		return nil
	}

	return c.UnmarshalCQL(nil, []byte(v))
}

func (c *cassVersion) UnmarshalCQL(info TypeInfo, data []byte) error {
	return c.unmarshal(data)
}

func (c *cassVersion) unmarshal(data []byte) error {
	version := strings.TrimSuffix(string(data), "-SNAPSHOT")
	version = strings.TrimPrefix(version, "v")
	v := strings.Split(version, ".")

	if len(v) < 2 {
		return fmt.Errorf("invalid version string: %s", data)
	}

	var err error
	c.Major, err = strconv.Atoi(v[0])
	if err != nil {
		return fmt.Errorf("invalid major version %v: %v", v[0], err)
	}

	c.Minor, err = strconv.Atoi(v[1])
	if err != nil {
		return fmt.Errorf("invalid minor version %v: %v", v[1], err)
	}

	if len(v) > 2 {
		c.Patch, err = strconv.Atoi(v[2])
		if err != nil {
			return fmt.Errorf("invalid patch version %v: %v", v[2], err)
		}
	}

	return nil
}

func (c cassVersion) Before(major, minor, patch int) bool {
	// We're comparing us (cassVersion) with the provided version (major, minor, patch)
	// We return true if our version is lower (comes before) than the provided one.
	if c.Major < major {
		return true
	} else if c.Major == major {
		if c.Minor < minor {
			return true
		} else if c.Minor == minor && c.Patch < patch {
			return true
		}

	}
	return false
}

func (c cassVersion) AtLeast(major, minor, patch int) bool {
	return !c.Before(major, minor, patch)
}

func (c cassVersion) String() string {
	return fmt.Sprintf("v%d.%d.%d", c.Major, c.Minor, c.Patch)
}

func (c cassVersion) nodeUpDelay() time.Duration {
	if c.Major >= 2 && c.Minor >= 2 {
		// CASSANDRA-8236
		return 0
	}

	return 10 * time.Second
}

type HostInfo struct {
	// TODO(zariel): reduce locking maybe, not all values will change, but to ensure
	// that we are thread safe use a mutex to access all fields.
	mu               sync.RWMutex
	hostname         string
	peer             net.IP
	broadcastAddress net.IP
	listenAddress    net.IP
	rpcAddress       net.IP
	preferredIP      net.IP
	connectAddress   net.IP
	port             int
	dataCenter       string
	rack             string
	hostId           string
	workload         string
	graph            bool
	dseVersion       string
	partitioner      string
	clusterName      string
	version          cassVersion
	state            nodeState
	schemaVersion    string
	tokens           []string
}

func (h *HostInfo) Equal(host *HostInfo) bool {
	if h == host {
		// prevent rlock reentry
		return true
	}

	return h.ConnectAddress().Equal(host.ConnectAddress())
}

func (h *HostInfo) Peer() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.peer
}

func (h *HostInfo) setPeer(peer net.IP) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.peer = peer
	return h
}

func (h *HostInfo) invalidConnectAddr() bool {
	h.mu.RLock()
	defer h.mu.RUnlock()
	addr, _ := h.connectAddressLocked()
	return !validIpAddr(addr)
}

func validIpAddr(addr net.IP) bool {
	return addr != nil && !addr.IsUnspecified()
}

func (h *HostInfo) connectAddressLocked() (net.IP, string) {
	if validIpAddr(h.connectAddress) {
		return h.connectAddress, "connect_address"
	} else if validIpAddr(h.rpcAddress) {
		return h.rpcAddress, "rpc_adress"
	} else if validIpAddr(h.preferredIP) {
		// where does perferred_ip get set?
		return h.preferredIP, "preferred_ip"
	} else if validIpAddr(h.broadcastAddress) {
		return h.broadcastAddress, "broadcast_address"
	} else if validIpAddr(h.peer) {
		return h.peer, "peer"
	}
	return net.IPv4zero, "invalid"
}

// Returns the address that should be used to connect to the host.
// If you wish to override this, use an AddressTranslator or
// use a HostFilter to SetConnectAddress()
func (h *HostInfo) ConnectAddress() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()

	if addr, _ := h.connectAddressLocked(); validIpAddr(addr) {
		return addr
	}
	panic(fmt.Sprintf("no valid connect address for host: %v. Is your cluster configured correctly?", h))
}

func (h *HostInfo) SetConnectAddress(address net.IP) *HostInfo {
	// TODO(zariel): should this not be exported?
	h.mu.Lock()
	defer h.mu.Unlock()
	h.connectAddress = address
	return h
}

func (h *HostInfo) BroadcastAddress() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.broadcastAddress
}

func (h *HostInfo) ListenAddress() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.listenAddress
}

func (h *HostInfo) RPCAddress() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.rpcAddress
}

func (h *HostInfo) PreferredIP() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.preferredIP
}

func (h *HostInfo) DataCenter() string {
	h.mu.RLock()
	dc := h.dataCenter
	h.mu.RUnlock()
	return dc
}

func (h *HostInfo) setDataCenter(dataCenter string) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.dataCenter = dataCenter
	return h
}

func (h *HostInfo) Rack() string {
	h.mu.RLock()
	rack := h.rack
	h.mu.RUnlock()
	return rack
}

func (h *HostInfo) setRack(rack string) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.rack = rack
	return h
}

func (h *HostInfo) HostID() string {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.hostId
}

func (h *HostInfo) setHostID(hostID string) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.hostId = hostID
	return h
}

func (h *HostInfo) WorkLoad() string {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.workload
}

func (h *HostInfo) Graph() bool {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.graph
}

func (h *HostInfo) DSEVersion() string {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.dseVersion
}

func (h *HostInfo) Partitioner() string {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.partitioner
}

func (h *HostInfo) ClusterName() string {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.clusterName
}

func (h *HostInfo) Version() cassVersion {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.version
}

func (h *HostInfo) setVersion(major, minor, patch int) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.version = cassVersion{major, minor, patch}
	return h
}

func (h *HostInfo) State() nodeState {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.state
}

func (h *HostInfo) setState(state nodeState) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.state = state
	return h
}

func (h *HostInfo) Tokens() []string {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.tokens
}

func (h *HostInfo) setTokens(tokens []string) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.tokens = tokens
	return h
}

func (h *HostInfo) Port() int {
	h.mu.RLock()
	defer h.mu.RUnlock()
	return h.port
}

func (h *HostInfo) setPort(port int) *HostInfo {
	h.mu.Lock()
	defer h.mu.Unlock()
	h.port = port
	return h
}

func (h *HostInfo) update(from *HostInfo) {
	if h == from {
		return
	}

	h.mu.Lock()
	defer h.mu.Unlock()

	from.mu.RLock()
	defer from.mu.RUnlock()

	// autogenerated do not update
	if h.peer == nil {
		h.peer = from.peer
	}
	if h.broadcastAddress == nil {
		h.broadcastAddress = from.broadcastAddress
	}
	if h.listenAddress == nil {
		h.listenAddress = from.listenAddress
	}
	if h.rpcAddress == nil {
		h.rpcAddress = from.rpcAddress
	}
	if h.preferredIP == nil {
		h.preferredIP = from.preferredIP
	}
	if h.connectAddress == nil {
		h.connectAddress = from.connectAddress
	}
	if h.port == 0 {
		h.port = from.port
	}
	if h.dataCenter == "" {
		h.dataCenter = from.dataCenter
	}
	if h.rack == "" {
		h.rack = from.rack
	}
	if h.hostId == "" {
		h.hostId = from.hostId
	}
	if h.workload == "" {
		h.workload = from.workload
	}
	if h.dseVersion == "" {
		h.dseVersion = from.dseVersion
	}
	if h.partitioner == "" {
		h.partitioner = from.partitioner
	}
	if h.clusterName == "" {
		h.clusterName = from.clusterName
	}
	if h.version == (cassVersion{}) {
		h.version = from.version
	}
	if h.tokens == nil {
		h.tokens = from.tokens
	}
}

func (h *HostInfo) IsUp() bool {
	return h != nil && h.State() == NodeUp
}

func (h *HostInfo) HostnameAndPort() string {
	if h.hostname == "" {
		h.hostname = h.ConnectAddress().String()
	}
	return net.JoinHostPort(h.hostname, strconv.Itoa(h.port))
}

func (h *HostInfo) String() string {
	h.mu.RLock()
	defer h.mu.RUnlock()

	connectAddr, source := h.connectAddressLocked()
	return fmt.Sprintf("[HostInfo hostname=%q connectAddress=%q peer=%q rpc_address=%q broadcast_address=%q "+
		"preferred_ip=%q connect_addr=%q connect_addr_source=%q "+
		"port=%d data_centre=%q rack=%q host_id=%q version=%q state=%s num_tokens=%d]",
		h.hostname, h.connectAddress, h.peer, h.rpcAddress, h.broadcastAddress, h.preferredIP,
		connectAddr, source,
		h.port, h.dataCenter, h.rack, h.hostId, h.version, h.state, len(h.tokens))
}

// Polls system.peers at a specific interval to find new hosts
type ringDescriber struct {
	session         *Session
	mu              sync.Mutex
	prevHosts       []*HostInfo
	prevPartitioner string
}

// Returns true if we are using system_schema.keyspaces instead of system.schema_keyspaces
func checkSystemSchema(control *controlConn) (bool, error) {
	iter := control.query("SELECT * FROM system_schema.keyspaces")
	if err := iter.err; err != nil {
		if errf, ok := err.(*errorFrame); ok {
			if errf.code == errSyntax {
				return false, nil
			}
		}

		return false, err
	}

	return true, nil
}

// Given a map that represents a row from either system.local or system.peers
// return as much information as we can in *HostInfo
func (s *Session) hostInfoFromMap(row map[string]interface{}, host *HostInfo) (*HostInfo, error) {
	const assertErrorMsg = "Assertion failed for %s"
	var ok bool

	// Default to our connected port if the cluster doesn't have port information
	for key, value := range row {
		switch key {
		case "data_center":
			host.dataCenter, ok = value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "data_center")
			}
		case "rack":
			host.rack, ok = value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "rack")
			}
		case "host_id":
			hostId, ok := value.(UUID)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "host_id")
			}
			host.hostId = hostId.String()
		case "release_version":
			version, ok := value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "release_version")
			}
			host.version.Set(version)
		case "peer":
			ip, ok := value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "peer")
			}
			host.peer = net.ParseIP(ip)
		case "cluster_name":
			host.clusterName, ok = value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "cluster_name")
			}
		case "partitioner":
			host.partitioner, ok = value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "partitioner")
			}
		case "broadcast_address":
			ip, ok := value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "broadcast_address")
			}
			host.broadcastAddress = net.ParseIP(ip)
		case "preferred_ip":
			ip, ok := value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "preferred_ip")
			}
			host.preferredIP = net.ParseIP(ip)
		case "rpc_address":
			ip, ok := value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "rpc_address")
			}
			host.rpcAddress = net.ParseIP(ip)
		case "listen_address":
			ip, ok := value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "listen_address")
			}
			host.listenAddress = net.ParseIP(ip)
		case "workload":
			host.workload, ok = value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "workload")
			}
		case "graph":
			host.graph, ok = value.(bool)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "graph")
			}
		case "tokens":
			host.tokens, ok = value.([]string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "tokens")
			}
		case "dse_version":
			host.dseVersion, ok = value.(string)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "dse_version")
			}
		case "schema_version":
			schemaVersion, ok := value.(UUID)
			if !ok {
				return nil, fmt.Errorf(assertErrorMsg, "schema_version")
			}
			host.schemaVersion = schemaVersion.String()
		}
		// TODO(thrawn01): Add 'port'? once CASSANDRA-7544 is complete
		// Not sure what the port field will be called until the JIRA issue is complete
	}

	ip, port := s.cfg.translateAddressPort(host.ConnectAddress(), host.port)
	host.connectAddress = ip
	host.port = port

	return host, nil
}

// Ask the control node for host info on all it's known peers
func (r *ringDescriber) getClusterPeerInfo() ([]*HostInfo, error) {
	var hosts []*HostInfo
	iter := r.session.control.withConnHost(func(ch *connHost) *Iter {
		hosts = append(hosts, ch.host)
		return ch.conn.query(context.TODO(), "SELECT * FROM system.peers")
	})

	if iter == nil {
		return nil, errNoControl
	}

	rows, err := iter.SliceMap()
	if err != nil {
		// TODO(zariel): make typed error
		return nil, fmt.Errorf("unable to fetch peer host info: %s", err)
	}

	for _, row := range rows {
		// extract all available info about the peer
		host, err := r.session.hostInfoFromMap(row, &HostInfo{port: r.session.cfg.Port})
		if err != nil {
			return nil, err
		} else if !isValidPeer(host) {
			// If it's not a valid peer
			Logger.Printf("Found invalid peer '%s' "+
				"Likely due to a gossip or snitch issue, this host will be ignored", host)
			continue
		}

		hosts = append(hosts, host)
	}

	return hosts, nil
}

// Return true if the host is a valid peer
func isValidPeer(host *HostInfo) bool {
	return !(len(host.RPCAddress()) == 0 ||
		host.hostId == "" ||
		host.dataCenter == "" ||
		host.rack == "" ||
		len(host.tokens) == 0)
}

// Return a list of hosts the cluster knows about
func (r *ringDescriber) GetHosts() ([]*HostInfo, string, error) {
	r.mu.Lock()
	defer r.mu.Unlock()

	hosts, err := r.getClusterPeerInfo()
	if err != nil {
		return r.prevHosts, r.prevPartitioner, err
	}

	var partitioner string
	if len(hosts) > 0 {
		partitioner = hosts[0].Partitioner()
	}

	return hosts, partitioner, nil
}

// Given an ip/port return HostInfo for the specified ip/port
func (r *ringDescriber) getHostInfo(ip net.IP, port int) (*HostInfo, error) {
	var host *HostInfo
	iter := r.session.control.withConnHost(func(ch *connHost) *Iter {
		if ch.host.ConnectAddress().Equal(ip) {
			host = ch.host
			return nil
		}

		return ch.conn.query(context.TODO(), "SELECT * FROM system.peers")
	})

	if iter != nil {
		rows, err := iter.SliceMap()
		if err != nil {
			return nil, err
		}

		for _, row := range rows {
			h, err := r.session.hostInfoFromMap(row, &HostInfo{port: port})
			if err != nil {
				return nil, err
			}

			if h.ConnectAddress().Equal(ip) {
				host = h
				break
			}
		}

		if host == nil {
			return nil, errors.New("host not found in peers table")
		}
	}

	if host == nil {
		return nil, errors.New("unable to fetch host info: invalid control connection")
	} else if host.invalidConnectAddr() {
		return nil, fmt.Errorf("host ConnectAddress invalid ip=%v: %v", ip, host)
	}

	return host, nil
}

func (r *ringDescriber) refreshRing() error {
	// if we have 0 hosts this will return the previous list of hosts to
	// attempt to reconnect to the cluster otherwise we would never find
	// downed hosts again, could possibly have an optimisation to only
	// try to add new hosts if GetHosts didnt error and the hosts didnt change.
	hosts, partitioner, err := r.GetHosts()
	if err != nil {
		return err
	}

	prevHosts := r.session.ring.currentHosts()

	// TODO: move this to session
	for _, h := range hosts {
		if filter := r.session.cfg.HostFilter; filter != nil && !filter.Accept(h) {
			continue
		}

		if host, ok := r.session.ring.addHostIfMissing(h); !ok {
			r.session.pool.addHost(h)
			r.session.policy.AddHost(h)
		} else {
			host.update(h)
		}
		delete(prevHosts, h.ConnectAddress().String())
	}

	// TODO(zariel): it may be worth having a mutex covering the overall ring state
	// in a session so that everything sees a consistent state. Becuase as is today
	// events can come in and due to ordering an UP host could be removed from the cluster
	for _, host := range prevHosts {
		r.session.removeHost(host)
	}

	r.session.metadata.setPartitioner(partitioner)
	r.session.policy.SetPartitioner(partitioner)
	return nil
}
