package server

import (
	"encoding/json"
	"net/http"
	"strconv"
	"time"

	"github.com/coreos/etcd/third_party/github.com/goraft/raft"
	"github.com/coreos/etcd/third_party/github.com/gorilla/mux"

	etcdErr "github.com/coreos/etcd/error"
	"github.com/coreos/etcd/log"
	uhttp "github.com/coreos/etcd/pkg/http"
	"github.com/coreos/etcd/store"
)

// Get all the current logs
func (ps *PeerServer) GetLogHttpHandler(w http.ResponseWriter, req *http.Request) {
	log.Debugf("[recv] GET %s/log", ps.Config.URL)
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(ps.raftServer.LogEntries())
}

// Response to vote request
func (ps *PeerServer) VoteHttpHandler(w http.ResponseWriter, req *http.Request) {
	rvreq := &raft.RequestVoteRequest{}

	if _, err := rvreq.Decode(req.Body); err != nil {
		http.Error(w, "", http.StatusBadRequest)
		log.Warnf("[recv] BADREQUEST %s/vote [%v]", ps.Config.URL, err)
		return
	}

	log.Debugf("[recv] POST %s/vote [%s]", ps.Config.URL, rvreq.CandidateName)

	resp := ps.raftServer.RequestVote(rvreq)

	if resp == nil {
		log.Warn("[vote] Error: nil response")
		http.Error(w, "", http.StatusInternalServerError)
		return
	}

	if _, err := resp.Encode(w); err != nil {
		log.Warn("[vote] Error: %v", err)
		http.Error(w, "", http.StatusInternalServerError)
		return
	}
}

// Response to append entries request
func (ps *PeerServer) AppendEntriesHttpHandler(w http.ResponseWriter, req *http.Request) {
	start := time.Now()
	aereq := &raft.AppendEntriesRequest{}

	if _, err := aereq.Decode(req.Body); err != nil {
		http.Error(w, "", http.StatusBadRequest)
		log.Warnf("[recv] BADREQUEST %s/log/append [%v]", ps.Config.URL, err)
		return
	}

	log.Debugf("[recv] POST %s/log/append [%d]", ps.Config.URL, len(aereq.Entries))

	ps.serverStats.RecvAppendReq(aereq.LeaderName, int(req.ContentLength))

	resp := ps.raftServer.AppendEntries(aereq)

	if resp == nil {
		log.Warn("[ae] Error: nil response")
		http.Error(w, "", http.StatusInternalServerError)
		return
	}

	if !resp.Success() {
		log.Debugf("[Append Entry] Step back")
	}

	if _, err := resp.Encode(w); err != nil {
		log.Warn("[ae] Error: %v", err)
		http.Error(w, "", http.StatusInternalServerError)
		return
	}

	(*ps.metrics).Timer("timer.appendentries.handle").UpdateSince(start)
}

// Response to recover from snapshot request
func (ps *PeerServer) SnapshotHttpHandler(w http.ResponseWriter, req *http.Request) {
	ssreq := &raft.SnapshotRequest{}

	if _, err := ssreq.Decode(req.Body); err != nil {
		http.Error(w, "", http.StatusBadRequest)
		log.Warnf("[recv] BADREQUEST %s/snapshot [%v]", ps.Config.URL, err)
		return
	}

	log.Debugf("[recv] POST %s/snapshot", ps.Config.URL)

	resp := ps.raftServer.RequestSnapshot(ssreq)

	if resp == nil {
		log.Warn("[ss] Error: nil response")
		http.Error(w, "", http.StatusInternalServerError)
		return
	}

	if _, err := resp.Encode(w); err != nil {
		log.Warn("[ss] Error: %v", err)
		http.Error(w, "", http.StatusInternalServerError)
		return
	}
}

// Response to recover from snapshot request
func (ps *PeerServer) SnapshotRecoveryHttpHandler(w http.ResponseWriter, req *http.Request) {
	ssrreq := &raft.SnapshotRecoveryRequest{}

	if _, err := ssrreq.Decode(req.Body); err != nil {
		http.Error(w, "", http.StatusBadRequest)
		log.Warnf("[recv] BADREQUEST %s/snapshotRecovery [%v]", ps.Config.URL, err)
		return
	}

	log.Debugf("[recv] POST %s/snapshotRecovery", ps.Config.URL)

	resp := ps.raftServer.SnapshotRecoveryRequest(ssrreq)

	if resp == nil {
		log.Warn("[ssr] Error: nil response")
		http.Error(w, "", http.StatusInternalServerError)
		return
	}

	if _, err := resp.Encode(w); err != nil {
		log.Warn("[ssr] Error: %v", err)
		http.Error(w, "", http.StatusInternalServerError)
		return
	}
}

// Get the port that listening for etcd connecting of the server
func (ps *PeerServer) EtcdURLHttpHandler(w http.ResponseWriter, req *http.Request) {
	log.Debugf("[recv] Get %s/etcdURL/ ", ps.Config.URL)
	w.WriteHeader(http.StatusOK)
	w.Write([]byte(ps.server.URL()))
}

// Response to the join request
func (ps *PeerServer) JoinHttpHandler(w http.ResponseWriter, req *http.Request) {
	command := &JoinCommand{}
	if err := uhttp.DecodeJsonRequest(req, command); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	log.Debugf("Receive Join Request from %s", command.Name)
	err := ps.server.Dispatch(command, w, req)

	// Return status.
	if err != nil {
		if etcdErr, ok := err.(*etcdErr.Error); ok {
			log.Debug("Return error: ", (*etcdErr).Error())
			etcdErr.Write(w)
		} else {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

// Response to remove request
func (ps *PeerServer) RemoveHttpHandler(w http.ResponseWriter, req *http.Request) {
	if req.Method != "DELETE" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	vars := mux.Vars(req)
	command := &RemoveCommand{
		Name: vars["name"],
	}

	log.Debugf("[recv] Remove Request [%s]", command.Name)

	ps.server.Dispatch(command, w, req)
}

// Returns a JSON-encoded cluster configuration.
func (ps *PeerServer) getClusterConfigHttpHandler(w http.ResponseWriter, req *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(ps.ClusterConfig())
}

// Updates the cluster configuration.
func (ps *PeerServer) setClusterConfigHttpHandler(w http.ResponseWriter, req *http.Request) {
	// Decode map.
	m := make(map[string]interface{})
	if err := json.NewDecoder(req.Body).Decode(&m); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Copy config and update fields passed in.
	config := ps.ClusterConfig()
	if activeSize, ok := m["activeSize"].(float64); ok {
		config.ActiveSize = int(activeSize)
	}
	if removeDelay, ok := m["removeDelay"].(float64); ok {
		config.RemoveDelay = removeDelay
	}
	if syncInterval, ok := m["syncInterval"].(float64); ok {
		config.SyncInterval = syncInterval
	}

	// Issue command to update.
	c := &SetClusterConfigCommand{Config: config}
	log.Debugf("[recv] Update Cluster Config Request")
	ps.server.Dispatch(c, w, req)

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(ps.ClusterConfig())
}

// Retrieves a list of peers and standbys.
func (ps *PeerServer) getMachinesHttpHandler(w http.ResponseWriter, req *http.Request) {
	machines := make([]*machineMessage, 0)
	leader := ps.raftServer.Leader()
	for _, name := range ps.registry.Names() {
		if msg := ps.getMachineMessage(name, leader); msg != nil {
			machines = append(machines, msg)
		}
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(&machines)
}

// Retrieve single peer or standby.
func (ps *PeerServer) getMachineHttpHandler(w http.ResponseWriter, req *http.Request) {
	vars := mux.Vars(req)
	m := ps.getMachineMessage(vars["name"], ps.raftServer.Leader())
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(m)
}

func (ps *PeerServer) getMachineMessage(name string, leader string) *machineMessage {
	if !ps.registry.Exists(name) {
		return nil
	}

	clientURL, _ := ps.registry.ClientURL(name)
	peerURL, _ := ps.registry.PeerURL(name)
	msg := &machineMessage{
		Name:      name,
		State:     raft.Follower,
		ClientURL: clientURL,
		PeerURL:   peerURL,
	}
	if name == leader {
		msg.State = raft.Leader
	}
	return msg
}

// Response to the name request
func (ps *PeerServer) NameHttpHandler(w http.ResponseWriter, req *http.Request) {
	log.Debugf("[recv] Get %s/name/ ", ps.Config.URL)
	w.WriteHeader(http.StatusOK)
	w.Write([]byte(ps.Config.Name))
}

// Response to the name request
func (ps *PeerServer) VersionHttpHandler(w http.ResponseWriter, req *http.Request) {
	log.Debugf("[recv] Get %s/version/ ", ps.Config.URL)
	w.WriteHeader(http.StatusOK)
	w.Write([]byte(strconv.Itoa(ps.store.Version())))
}

// Checks whether a given version is supported.
func (ps *PeerServer) VersionCheckHttpHandler(w http.ResponseWriter, req *http.Request) {
	log.Debugf("[recv] Get %s%s ", ps.Config.URL, req.URL.Path)
	vars := mux.Vars(req)
	version, _ := strconv.Atoi(vars["version"])
	if version >= store.MinVersion() && version <= store.MaxVersion() {
		w.WriteHeader(http.StatusOK)
	} else {
		w.WriteHeader(http.StatusForbidden)
	}
}

// Upgrades the current store version to the next version.
func (ps *PeerServer) UpgradeHttpHandler(w http.ResponseWriter, req *http.Request) {
	log.Debugf("[recv] Get %s/version", ps.Config.URL)

	// Check if upgrade is possible for all nodes.
	if err := ps.Upgradable(); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Create an upgrade command from the current version.
	c := ps.store.CommandFactory().CreateUpgradeCommand()
	if err := ps.server.Dispatch(c, w, req); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.WriteHeader(http.StatusOK)
}

// machineMessage represents information about a peer or standby in the registry.
type machineMessage struct {
	Name      string `json:"name"`
	State     string `json:"state"`
	ClientURL string `json:"clientURL"`
	PeerURL   string `json:"peerURL"`
}