package consensus

import (
	"github.com/filecoin-project/lotus/node/repo"
	"io/ioutil"
	"path/filepath"
	"time"

	hraft "github.com/hashicorp/raft"
	"github.com/libp2p/go-libp2p/core/peer"
	"golang.org/x/xerrors"

	"github.com/filecoin-project/lotus/node/config"
)

// ConfigKey is the default configuration key for holding this component's
// configuration section.
var configKey = "raft"
var envConfigKey = "cluster_raft"

// Configuration defaults
var (
	DefaultDataSubFolder        = "raft-cluster"
	DefaultWaitForLeaderTimeout = 15 * time.Second
	DefaultCommitRetries        = 1
	DefaultNetworkTimeout       = 100 * time.Second
	DefaultCommitRetryDelay     = 200 * time.Millisecond
	DefaultBackupsRotate        = 6
	DefaultDatastoreNamespace   = "/r" // from "/raft"
)

// ClusterRaftConfig allows to configure the Raft Consensus component for the node cluster.
type ClusterRaftConfig struct {
	// config to enabled node cluster with raft consensus
	ClusterModeEnabled bool
	// will shutdown libp2p host on shutdown. Useful for testing
	HostShutdown bool
	// A folder to store Raft's data.
	DataFolder string
	// InitPeerset provides the list of initial cluster peers for new Raft
	// peers (with no prior state). It is ignored when Raft was already
	// initialized or when starting in staging mode.
	InitPeerset []peer.ID
	// LeaderTimeout specifies how long to wait for a leader before
	// failing an operation.
	WaitForLeaderTimeout time.Duration
	// NetworkTimeout specifies how long before a Raft network
	// operation is timed out
	NetworkTimeout time.Duration
	// CommitRetries specifies how many times we retry a failed commit until
	// we give up.
	CommitRetries int
	// How long to wait between retries
	CommitRetryDelay time.Duration
	// BackupsRotate specifies the maximum number of Raft's DataFolder
	// copies that we keep as backups (renaming) after cleanup.
	BackupsRotate int
	// Namespace to use when writing keys to the datastore
	DatastoreNamespace string

	// A Hashicorp Raft's configuration object.
	RaftConfig *hraft.Config

	// Tracing enables propagation of contexts across binary boundaries.
	Tracing bool
}

func DefaultClusterRaftConfig() *ClusterRaftConfig {
	var cfg ClusterRaftConfig
	cfg.DataFolder = "" // empty so it gets omitted
	cfg.InitPeerset = []peer.ID{}
	cfg.WaitForLeaderTimeout = DefaultWaitForLeaderTimeout
	cfg.NetworkTimeout = DefaultNetworkTimeout
	cfg.CommitRetries = DefaultCommitRetries
	cfg.CommitRetryDelay = DefaultCommitRetryDelay
	cfg.BackupsRotate = DefaultBackupsRotate
	cfg.DatastoreNamespace = DefaultDatastoreNamespace
	cfg.RaftConfig = hraft.DefaultConfig()

	// These options are imposed over any Default Raft Config.
	cfg.RaftConfig.ShutdownOnRemove = false
	cfg.RaftConfig.LocalID = "will_be_set_automatically"

	// Set up logging
	cfg.RaftConfig.LogOutput = ioutil.Discard
	//cfg.RaftConfig.Logger = &hcLogToLogger{}
	return &cfg
}

func NewClusterRaftConfig(userRaftConfig *config.UserRaftConfig) *ClusterRaftConfig {
	var cfg ClusterRaftConfig
	cfg.DataFolder = userRaftConfig.DataFolder
	cfg.InitPeerset = userRaftConfig.InitPeerset
	cfg.WaitForLeaderTimeout = time.Duration(userRaftConfig.WaitForLeaderTimeout)
	cfg.NetworkTimeout = time.Duration(userRaftConfig.NetworkTimeout)
	cfg.CommitRetries = userRaftConfig.CommitRetries
	cfg.CommitRetryDelay = time.Duration(userRaftConfig.CommitRetryDelay)
	cfg.BackupsRotate = userRaftConfig.BackupsRotate
	cfg.DatastoreNamespace = userRaftConfig.DatastoreNamespace

	// Keep this to be default hraft config for now
	cfg.RaftConfig = hraft.DefaultConfig()

	// These options are imposed over any Default Raft Config.
	cfg.RaftConfig.ShutdownOnRemove = false
	cfg.RaftConfig.LocalID = "will_be_set_automatically"

	// Set up logging
	cfg.RaftConfig.LogOutput = ioutil.Discard
	//cfg.RaftConfig.Logger = &hcLogToLogger{}
	return &cfg

}

// ConfigJSON represents a human-friendly Config
// object which can be saved to JSON.  Most configuration keys are converted
// into simple types like strings, and key names aim to be self-explanatory
// for the user.
// Check https://godoc.org/github.com/hashicorp/raft#Config for extended
// description on all Raft-specific keys.
//type jsonConfig struct {
//	// Storage folder for snapshots, log store etc. Used by
//	// the Raft.
//	DataFolder string `json:"data_folder,omitempty"`
//
//	// InitPeerset provides the list of initial cluster peers for new Raft
//	// peers (with no prior state). It is ignored when Raft was already
//	// initialized or when starting in staging mode.
//	InitPeerset []string `json:"init_peerset"`
//
//	// How long to wait for a leader before failing
//	WaitForLeaderTimeout string `json:"wait_for_leader_timeout"`
//
//	// How long to wait before timing out network operations
//	NetworkTimeout string `json:"network_timeout"`
//
//	// How many retries to make upon a failed commit
//	CommitRetries int `json:"commit_retries"`
//
//	// How long to wait between commit retries
//	CommitRetryDelay string `json:"commit_retry_delay"`
//
//	// BackupsRotate specifies the maximum number of Raft's DataFolder
//	// copies that we keep as backups (renaming) after cleanup.
//	BackupsRotate int `json:"backups_rotate"`
//
//	DatastoreNamespace string `json:"datastore_namespace,omitempty"`
//
//	// HeartbeatTimeout specifies the time in follower state without
//	// a leader before we attempt an election.
//	HeartbeatTimeout string `json:"heartbeat_timeout,omitempty"`
//
//	// ElectionTimeout specifies the time in candidate state without
//	// a leader before we attempt an election.
//	ElectionTimeout string `json:"election_timeout,omitempty"`
//
//	// CommitTimeout controls the time without an Apply() operation
//	// before we heartbeat to ensure a timely commit.
//	CommitTimeout string `json:"commit_timeout,omitempty"`
//
//	// MaxAppendEntries controls the maximum number of append entries
//	// to send at once.
//	MaxAppendEntries int `json:"max_append_entries,omitempty"`
//
//	// TrailingLogs controls how many logs we leave after a snapshot.
//	TrailingLogs uint64 `json:"trailing_logs,omitempty"`
//
//	// SnapshotInterval controls how often we check if we should perform
//	// a snapshot.
//	SnapshotInterval string `json:"snapshot_interval,omitempty"`
//
//	// SnapshotThreshold controls how many outstanding logs there must be
//	// before we perform a snapshot.
//	SnapshotThreshold uint64 `json:"snapshot_threshold,omitempty"`
//
//	// LeaderLeaseTimeout is used to control how long the "lease" lasts
//	// for being the leader without being able to contact a quorum
//	// of nodes. If we reach this interval without contact, we will
//	// step down as leader.
//	LeaderLeaseTimeout string `json:"leader_lease_timeout,omitempty"`
//
//	// The unique ID for this server across all time. When running with
//	// ProtocolVersion < 3, you must set this to be the same as the network
//	// address of your transport.
//	// LocalID string `json:local_id`
//}

// ConfigKey returns a human-friendly indentifier for this Config.
//func (cfg *config.ClusterRaftConfig) ConfigKey() string {
//	return configKey
//}

//// Validate checks that this configuration has working values,
//// at least in appearance.
func ValidateConfig(cfg *ClusterRaftConfig) error {
	if cfg.RaftConfig == nil {
		return xerrors.Errorf("no hashicorp/raft.Config")
	}
	if cfg.WaitForLeaderTimeout <= 0 {
		return xerrors.Errorf("wait_for_leader_timeout <= 0")
	}

	if cfg.NetworkTimeout <= 0 {
		return xerrors.Errorf("network_timeout <= 0")
	}

	if cfg.CommitRetries < 0 {
		return xerrors.Errorf("commit_retries is invalid")
	}

	if cfg.CommitRetryDelay <= 0 {
		return xerrors.Errorf("commit_retry_delay is invalid")
	}

	if cfg.BackupsRotate <= 0 {
		return xerrors.Errorf("backups_rotate should be larger than 0")
	}

	return hraft.ValidateConfig(cfg.RaftConfig)
}

// LoadJSON parses a json-encoded configuration (see jsonConfig).
// The Config will have default values for all fields not explicited
// in the given json object.
//func (cfg *Config) LoadJSON(raw []byte) error {
//	jcfg := &jsonConfig{}
//	err := json.Unmarshal(raw, jcfg)
//	if err != nil {
//		logger.Error("Error unmarshaling raft config")
//		return err
//	}
//
//	cfg.Default()
//
//	return cfg.applyJSONConfig(jcfg)
//}
//
//func (cfg *Config) applyJSONConfig(jcfg *jsonConfig) error {
//	parseDuration := func(txt string) time.Duration {
//		d, _ := time.ParseDuration(txt)
//		if txt != "" && d == 0 {
//			logger.Warnf("%s is not a valid duration. Default will be used", txt)
//		}
//		return d
//	}
//
//	// Parse durations. We ignore errors as 0 will take Default values.
//	waitForLeaderTimeout := parseDuration(jcfg.WaitForLeaderTimeout)
//	networkTimeout := parseDuration(jcfg.NetworkTimeout)
//	commitRetryDelay := parseDuration(jcfg.CommitRetryDelay)
//	heartbeatTimeout := parseDuration(jcfg.HeartbeatTimeout)
//	electionTimeout := parseDuration(jcfg.ElectionTimeout)
//	commitTimeout := parseDuration(jcfg.CommitTimeout)
//	snapshotInterval := parseDuration(jcfg.SnapshotInterval)
//	leaderLeaseTimeout := parseDuration(jcfg.LeaderLeaseTimeout)
//
//	// Set all values in config. For some, take defaults if they are 0.
//	// Set values from jcfg if they are not 0 values
//
//	// Own values
//	config.SetIfNotDefault(jcfg.DataFolder, &cfg.DataFolder)
//	config.SetIfNotDefault(waitForLeaderTimeout, &cfg.WaitForLeaderTimeout)
//	config.SetIfNotDefault(networkTimeout, &cfg.NetworkTimeout)
//	cfg.CommitRetries = jcfg.CommitRetries
//	config.SetIfNotDefault(commitRetryDelay, &cfg.CommitRetryDelay)
//	config.SetIfNotDefault(jcfg.BackupsRotate, &cfg.BackupsRotate)
//
//	// Raft values
//	config.SetIfNotDefault(heartbeatTimeout, &cfg.RaftConfig.HeartbeatTimeout)
//	config.SetIfNotDefault(electionTimeout, &cfg.RaftConfig.ElectionTimeout)
//	config.SetIfNotDefault(commitTimeout, &cfg.RaftConfig.CommitTimeout)
//	config.SetIfNotDefault(jcfg.MaxAppendEntries, &cfg.RaftConfig.MaxAppendEntries)
//	config.SetIfNotDefault(jcfg.TrailingLogs, &cfg.RaftConfig.TrailingLogs)
//	config.SetIfNotDefault(snapshotInterval, &cfg.RaftConfig.SnapshotInterval)
//	config.SetIfNotDefault(jcfg.SnapshotThreshold, &cfg.RaftConfig.SnapshotThreshold)
//	config.SetIfNotDefault(leaderLeaseTimeout, &cfg.RaftConfig.LeaderLeaseTimeout)
//
//	cfg.InitPeerset = api.StringsToPeers(jcfg.InitPeerset)
//	return cfg.Validate()
//}
//
//// ToJSON returns the pretty JSON representation of a Config.
//func (cfg *Config) ToJSON() ([]byte, error) {
//	jcfg := cfg.toJSONConfig()
//
//	return config.DefaultJSONMarshal(jcfg)
//}
//
//func (cfg *Config) toJSONConfig() *jsonConfig {
//	jcfg := &jsonConfig{
//		DataFolder:           cfg.DataFolder,
//		InitPeerset:          api.PeersToStrings(cfg.InitPeerset),
//		WaitForLeaderTimeout: cfg.WaitForLeaderTimeout.String(),
//		NetworkTimeout:       cfg.NetworkTimeout.String(),
//		CommitRetries:        cfg.CommitRetries,
//		CommitRetryDelay:     cfg.CommitRetryDelay.String(),
//		BackupsRotate:        cfg.BackupsRotate,
//		HeartbeatTimeout:     cfg.RaftConfig.HeartbeatTimeout.String(),
//		ElectionTimeout:      cfg.RaftConfig.ElectionTimeout.String(),
//		CommitTimeout:        cfg.RaftConfig.CommitTimeout.String(),
//		MaxAppendEntries:     cfg.RaftConfig.MaxAppendEntries,
//		TrailingLogs:         cfg.RaftConfig.TrailingLogs,
//		SnapshotInterval:     cfg.RaftConfig.SnapshotInterval.String(),
//		SnapshotThreshold:    cfg.RaftConfig.SnapshotThreshold,
//		LeaderLeaseTimeout:   cfg.RaftConfig.LeaderLeaseTimeout.String(),
//	}
//	if cfg.DatastoreNamespace != DefaultDatastoreNamespace {
//		jcfg.DatastoreNamespace = cfg.DatastoreNamespace
//		// otherwise leave empty so it gets omitted.
//	}
//	return jcfg
//}
//
// Default initializes this configuration with working defaults.
//func (cfg *config.ClusterRaftConfig) Default() {
//	cfg.DataFolder = "" // empty so it gets omitted
//	cfg.InitPeerset = []peer.ID{}
//	cfg.WaitForLeaderTimeout = DefaultWaitForLeaderTimeout
//	cfg.NetworkTimeout = DefaultNetworkTimeout
//	cfg.CommitRetries = DefaultCommitRetries
//	cfg.CommitRetryDelay = DefaultCommitRetryDelay
//	cfg.BackupsRotate = DefaultBackupsRotate
//	cfg.DatastoreNamespace = DefaultDatastoreNamespace
//	cfg.RaftConfig = hraft.DefaultConfig()
//
//	// These options are imposed over any Default Raft Config.
//	cfg.RaftConfig.ShutdownOnRemove = false
//	cfg.RaftConfig.LocalID = "will_be_set_automatically"
//
//	// Set up logging
//	cfg.RaftConfig.LogOutput = ioutil.Discard
//	//cfg.RaftConfig.Logger = &hcLogToLogger{}
//}
//
//func NewDefaultConfig() *config.ClusterRaftConfig {
//	var cfg config.ClusterRaftConfig
//	cfg.Default()
//	return &cfg
//}

//
//// ApplyEnvVars fills in any Config fields found
//// as environment variables.
//func (cfg *Config) ApplyEnvVars() error {
//	jcfg := cfg.toJSONConfig()
//
//	err := envconfig.Process(envConfigKey, jcfg)
//	if err != nil {
//		return err
//	}
//
//	return cfg.applyJSONConfig(jcfg)
//}
//
// GetDataFolder returns the Raft data folder that we are using.
func (cfg *ClusterRaftConfig) GetDataFolder(repo repo.LockedRepo) string {
	if cfg.DataFolder == "" {
		return filepath.Join(repo.Path() + DefaultDataSubFolder)
	}
	return filepath.Join(repo.Path() + cfg.DataFolder)
}

//
//// ToDisplayJSON returns JSON config as a string.
//func (cfg *Config) ToDisplayJSON() ([]byte, error) {
//	return config.DisplayJSON(cfg.toJSONConfig())
//}