// Package client provides a Go Client for the IPFS Cluster API provided
// by the "api/rest" component. It supports both the HTTP(s) endpoint and
// the libp2p-http endpoint.
package client

import (
	"context"
	"fmt"
	"net/http"
	"time"

	"github.com/ipfs/go-ipfs-cmdkit/files"

	"github.com/ipfs/ipfs-cluster/api"

	cid "github.com/ipfs/go-cid"
	shell "github.com/ipfs/go-ipfs-api"
	logging "github.com/ipfs/go-log"
	host "github.com/libp2p/go-libp2p-host"
	peer "github.com/libp2p/go-libp2p-peer"
	ma "github.com/multiformats/go-multiaddr"
	madns "github.com/multiformats/go-multiaddr-dns"
	manet "github.com/multiformats/go-multiaddr-net"
)

// Configuration defaults
var (
	DefaultTimeout   = 0
	DefaultAPIAddr   = "/ip4/127.0.0.1/tcp/9094"
	DefaultLogLevel  = "info"
	DefaultProxyPort = 9095
	ResolveTimeout   = 30 * time.Second
	DefaultPort      = 9094
)

var loggingFacility = "apiclient"
var logger = logging.Logger(loggingFacility)

// Client interface defines the interface to be used by API clients to
// interact with the ipfs-cluster-service
type Client interface {
	// ID returns information about the cluster Peer.
	ID() (api.ID, error)

	// Peers requests ID information for all cluster peers.
	Peers() ([]api.ID, error)
	// PeerAdd adds a new peer to the cluster.
	PeerAdd(pid peer.ID) (api.ID, error)
	// PeerRm removes a current peer from the cluster
	PeerRm(pid peer.ID) error

	// Add imports files to the cluster from the given paths.
	Add(paths []string, params *api.AddParams, out chan<- *api.AddedOutput) error
	// AddMultiFile imports new files from a MultiFileReader.
	AddMultiFile(multiFileR *files.MultiFileReader, params *api.AddParams, out chan<- *api.AddedOutput) error

	// Pin tracks a Cid with the given replication factor and a name for
	// human-friendliness.
	Pin(ci cid.Cid, replicationFactorMin, replicationFactorMax int, name string) error
	// Unpin untracks a Cid from cluster.
	Unpin(ci cid.Cid) error

	// Allocations returns the consensus state listing all tracked items
	// and the peers that should be pinning them.
	Allocations(filter api.PinType) ([]api.Pin, error)
	// Allocation returns the current allocations for a given Cid.
	Allocation(ci cid.Cid) (api.Pin, error)

	// Status returns the current ipfs state for a given Cid. If local is true,
	// the information affects only the current peer, otherwise the information
	// is fetched from all cluster peers.
	Status(ci cid.Cid, local bool) (api.GlobalPinInfo, error)
	// StatusAll gathers Status() for all tracked items.
	StatusAll(local bool) ([]api.GlobalPinInfo, error)

	// Sync makes sure the state of a Cid corresponds to the state reported
	// by the ipfs daemon, and returns it. If local is true, this operation
	// only happens on the current peer, otherwise it happens on every
	// cluster peer.
	Sync(ci cid.Cid, local bool) (api.GlobalPinInfo, error)
	// SyncAll triggers Sync() operations for all tracked items. It only
	// returns informations for items that were de-synced or have an error
	// state. If local is true, the operation is limited to the current
	// peer. Otherwise it happens on every cluster peer.
	SyncAll(local bool) ([]api.GlobalPinInfo, error)

	// Recover retriggers pin or unpin ipfs operations for a Cid in error
	// state.  If local is true, the operation is limited to the current
	// peer, otherwise it happens on every cluster peer.
	Recover(ci cid.Cid, local bool) (api.GlobalPinInfo, error)
	// RecoverAll triggers Recover() operations on all tracked items. If
	// local is true, the operation is limited to the current peer.
	// Otherwise, it happens everywhere.
	RecoverAll(local bool) ([]api.GlobalPinInfo, error)

	// Version returns the ipfs-cluster peer's version.
	Version() (api.Version, error)

	// IPFS returns an instance of go-ipfs-api's Shell, pointing to a
	// Cluster's IPFS proxy endpoint.
	IPFS() *shell.Shell

	// GetConnectGraph returns an ipfs-cluster connection graph.  The
	// serialized version, strings instead of pids, is returned
	GetConnectGraph() (api.ConnectGraphSerial, error)
}

// Config allows to configure the parameters to connect
// to the ipfs-cluster REST API.
type Config struct {
	// Enable SSL support. Only valid without PeerAddr.
	SSL bool
	// Skip certificate verification (insecure)
	NoVerifyCert bool

	// Username and password for basic authentication
	Username string
	Password string

	// The ipfs-cluster REST API endpoint in multiaddress form
	// (takes precedence over host:port). It this address contains
	// an /ipfs/, /p2p/ or /dnsaddr, the API will be contacted
	// through a libp2p tunnel, thus getting encryption for
	// free. Using the libp2p tunnel will ignore any configurations.
	APIAddr ma.Multiaddr

	// PeerAddr is deprecated. It's aliased to APIAddr
	PeerAddr ma.Multiaddr

	// REST API endpoint host and port. Only valid without
	// APIAddr and PeerAddr
	Host string
	Port string

	// If PeerAddr is provided, and the peer uses private networks
	// (pnet), then we need to provide the key. If the peer is the
	// cluster peer, this corresponds to the cluster secret.
	ProtectorKey []byte

	// ProxyAddr is used to obtain a go-ipfs-api Shell instance pointing
	// to the ipfs proxy endpoint of ipfs-cluster. If empty, the location
	// will be guessed from one of APIAddr/Host,
	// and the port used will be ipfs-cluster's proxy default port (9095)
	ProxyAddr ma.Multiaddr

	// Define timeout for network operations
	Timeout time.Duration

	// Specifies if we attempt to re-use connections to the same
	// hosts.
	DisableKeepAlives bool

	// LogLevel defines the verbosity of the logging facility
	LogLevel string
}

// DefaultClient provides methods to interact with the ipfs-cluster API. Use
// NewDefaultClient() to create one.
type defaultClient struct {
	ctx       context.Context
	cancel    func()
	config    *Config
	transport *http.Transport
	net       string
	hostname  string
	client    *http.Client
	p2p       host.Host
}

// NewDefaultClient initializes a client given a Config.
func NewDefaultClient(cfg *Config) (Client, error) {
	ctx := context.Background()
	client := &defaultClient{
		ctx:    ctx,
		config: cfg,
	}

	if paddr := client.config.PeerAddr; paddr != nil {
		client.config.APIAddr = paddr
	}

	if client.config.Port == "" {
		client.config.Port = fmt.Sprintf("%d", DefaultPort)
	}

	err := client.setupAPIAddr()
	if err != nil {
		return nil, err
	}

	err = client.resolveAPIAddr()
	if err != nil {
		return nil, err
	}

	err = client.setupHTTPClient()
	if err != nil {
		return nil, err
	}

	err = client.setupHostname()
	if err != nil {
		return nil, err
	}

	err = client.setupProxy()
	if err != nil {
		return nil, err
	}

	if lvl := cfg.LogLevel; lvl != "" {
		logging.SetLogLevel(loggingFacility, lvl)
	} else {
		logging.SetLogLevel(loggingFacility, DefaultLogLevel)
	}

	return client, nil
}

func (c *defaultClient) setupAPIAddr() error {
	var addr ma.Multiaddr
	var err error
	if c.config.APIAddr == nil {
		if c.config.Host == "" { //default
			addr, err = ma.NewMultiaddr(DefaultAPIAddr)
		} else {
			addrStr := fmt.Sprintf("/dns4/%s/tcp/%s", c.config.Host, c.config.Port)
			addr, err = ma.NewMultiaddr(addrStr)
		}
		c.config.APIAddr = addr
		return err
	}

	return nil
}

func (c *defaultClient) resolveAPIAddr() error {
	resolveCtx, cancel := context.WithTimeout(c.ctx, ResolveTimeout)
	defer cancel()
	resolved, err := madns.Resolve(resolveCtx, c.config.APIAddr)
	if err != nil {
		return err
	}

	if len(resolved) == 0 {
		return fmt.Errorf("resolving %s returned 0 results", c.config.APIAddr)
	}

	c.config.APIAddr = resolved[0]
	return nil
}

func (c *defaultClient) setupHTTPClient() error {
	var err error

	switch {
	case IsPeerAddress(c.config.APIAddr):
		err = c.enableLibp2p()
	case c.config.SSL:
		err = c.enableTLS()
	default:
		c.defaultTransport()
	}

	if err != nil {
		return err
	}

	c.client = &http.Client{
		Transport: c.transport,
		Timeout:   c.config.Timeout,
	}
	return nil
}

func (c *defaultClient) setupHostname() error {
	// Extract host:port form APIAddr or use Host:Port.
	// For libp2p, hostname is set in enableLibp2p()
	if !IsPeerAddress(c.config.APIAddr) {
		_, hostname, err := manet.DialArgs(c.config.APIAddr)
		if err != nil {
			return err
		}
		c.hostname = hostname
	}
	return nil
}

func (c *defaultClient) setupProxy() error {
	if c.config.ProxyAddr != nil {
		return nil
	}

	// Guess location from	APIAddr
	port, err := ma.NewMultiaddr(fmt.Sprintf("/tcp/%d", DefaultProxyPort))
	if err != nil {
		return err
	}
	c.config.ProxyAddr = ma.Split(c.config.APIAddr)[0].Encapsulate(port)
	return nil
}

// IPFS returns an instance of go-ipfs-api's Shell, pointing to the
// configured ProxyAddr (or to the default Cluster's IPFS proxy port).
// It re-uses this Client's HTTP client, thus will be constrained by
// the same configurations affecting it (timeouts...).
func (c *defaultClient) IPFS() *shell.Shell {
	return shell.NewShellWithClient(c.config.ProxyAddr.String(), c.client)
}

// IsPeerAddress detects if the given multiaddress identifies a libp2p peer,
// either because it has the /p2p/ protocol or because it uses /dnsaddr/
func IsPeerAddress(addr ma.Multiaddr) bool {
	if addr == nil {
		return false
	}
	pid, err := addr.ValueForProtocol(ma.P_IPFS)
	dnsaddr, err2 := addr.ValueForProtocol(madns.DnsaddrProtocol.Code)
	return (pid != "" && err == nil) || (dnsaddr != "" && err2 == nil)
}