.TP
.B Not_A_Type
TODOC

.TP
.B Keepalive
The Keepalive message serves as an introduction and beaconing mechanism for
the Nano real-time network.
The Keepalive message requires exactly 8 IPv6 address and port number
tuples to be sent as its payload.  The IPv6 addresses are each 128-bits
(16-bytes) long and the port numbers are 16-bit integers sent in network byte
order.  The payload for the Keepalive message type is 144 bytes in size.
(16-bytes) long and the port numbers are 16-bit integers sent in little endian
byte order.  The payload for the Keepalive message type is 144 bytes in size.

.TP
.B Publish
TODOC

.TP
.B Confirm_Req
TODOC

.TP
.B Confirm_Ack
TODOC

.TP
.B Bulk_Pull
The Bulk_Pull message is used to pull the entire chain for an account, down to
its beginning or to a given block.  It takes 2 arguments, both of them 256-bit.
The first argument is the account, so its 256-bit public key should be encoded
as binary in big-endian notation.  The second argument is the block hash to
stop sending at, or 256 bits of 0s to indicate that the entire chain should be
sent.  The payload for Bulk_Pull messages is 64 bytes in size.
TODOC

The response from a Bulk_Pull request will be a stream of tuples, each
containing a 256-bit block hash, and a block message.  TODOC: Format

.TP
.B Bulk_Push
TODOC

.TP
.B Frontier_Req
The Frontier_Req message is used to pull a list of accounts from a remote node
for the purpose of bootstrapping.  It requires 3 arguments:  The 256-bit
public key of an account to start with, a 32-bit integer denoting the age of
accounts to return, and a 32-bit integer denoting the number of records to
return.  If the
.I age
parameter is
.B 0xffffffff
then all records are returned, regardless of age.  If the
.I count
parameter is
.B 0xffffffff
then all records are returned and no limit is imposed.
TODOC

The response from a Frontier_Req is a 256-bit public key, and the 256-bit
block hash that corresponds to the frontier (most recent block) for that
account's blockchain from the node where the response was generated.

.TP
.B Bulk_Pull_Blocks
TODOC


.SH PROCEDURES

#! /usr/bin/env tclsh

package require Tcl 8.6.4

package require json
package require json::write

namespace eval ::nano {}
namespace eval ::nano::address {}
namespace eval ::nano::key {}
namespace eval ::nano::block {}
namespace eval ::nano::block::json {}
namespace eval ::nano::block::dict {}
namespace eval ::nano::block::create {}
namespace eval ::nano::work {}
namespace eval ::nano::account {}
namespace eval ::nano::node {}
namespace eval ::nano::ledger {}
namespace eval ::nano::ledger::lmdb {}
namespace eval ::nano::rpc {}
namespace eval ::nano::rpc::client {}
namespace eval ::nano::balance {}
namespace eval ::nano::node::server {}
namespace eval ::nano::node::bootstrap {}
namespace eval ::nano::node::p2p {}
namespace eval ::nano::network::client {}
namespace eval ::nano::network::server {}
namespace eval ::nano::network::_dns {}

# Constants
set ::nano::block::stateBlockPreamble [binary decode hex "0000000000000000000000000000000000000000000000000000000000000006"]
set ::nano::block::zero "0000000000000000000000000000000000000000000000000000000000000000"
set ::nano::address::zero $::nano::block::zero
set ::nano::address::base32alphabet {13456789abcdefghijkmnopqrstuwxyz}
set ::nano::network::messageTypes {
	"invalid"
	"not_a_type"
	"keepalive"
	"publish"
	"confirm_req"
	"confirm_ack"
	"bulk_pull"
	"bulk_push"
	"frontier_req"
	"bulk_pull_blocks"
}
set ::nano::balance::_conversion {
	GNano 1000000000000000000000000000000000000000
	MNano 1000000000000000000000000000000000000
	Gnano 1000000000000000000000000000000000
	Gxrb  1000000000000000000000000000000000
	KNano 1000000000000000000000000000000000
	Nano  1000000000000000000000000000000
	_USER 1000000000000000000000000000000
	NANO  1000000000000000000000000000000
	Mnano 1000000000000000000000000000000
	Mxrb  1000000000000000000000000000000
	Mrai  1000000000000000000000000000000
	knano 1000000000000000000000000000
	kxrb  1000000000000000000000000000
	mNano 1000000000000000000000000000
	nano  1000000000000000000000000
	xrb   1000000000000000000000000
	uNano 1000000000000000000000000
	mnano 1000000000000000000000
	mxrb  1000000000000000000000
	unano 1000000000000000000
	uxrb  1000000000000000000
	Traw  1000000000000
	Graw  1000000000
	Mraw  1000000
	Kraw  1000
	raw   1
}

# Address management functions
proc ::nano::address::toPublicKey {address args} {
	set performChecksumCheck false
	set outputFormat "bytes"
	foreach arg $args {
		switch -exact -- $arg {

	}

	# Parse out the work data
	if {[dict get $retval "type"] in {send receive change state}} {
		set workDataBasedOn "previous"
	}

	if {[dict get $retval "type"] eq "state" && [dict get $retval "previous"] eq "0000000000000000000000000000000000000000000000000000000000000000" && [dict get $retval "link"] eq "0000000000000000000000000000000000000000000000000000000000000000"} {
	if {[dict get $retval "type"] eq "state" && [dict get $retval "previous"] eq $::nano::block::zero && [dict get $retval "link"] eq $::nano::block::zero} {
		set workDataBasedOn "account"
	}

	if {[dict get $retval "type"] eq "open"} {
		set workDataBasedOn "account"
	}

	array set block $args

	if {![info exists block(representative)]} {
		set block(representative) $block(to)
	}

	if {![info exists block(previous)]} {
		set block(previous) "0000000000000000000000000000000000000000000000000000000000000000"
		set block(previous) $::nano::block::zero
		set block(previousBalance) 0
		set block(_workData) [::nano::address::toPublicKey $block(to) -hex]
	} else {
		set block(_workData) $block(previous)
	}

	set block(balance) [expr {$block(previousBalance) + $block(amount)}]

# Usage:
#   setRepresentative account <account> previous <previousBlockHash>
#                     representative <newRepresentative> balance <balance>
proc ::nano::block::create::setRepresentative {args} {
	array set block $args

	set block(link) "0000000000000000000000000000000000000000000000000000000000000000"
	set block(link) $::nano::block::zero

	set blockDict [dict create \
		"type" state \
		"account" $block(account) \
		"previous" $block(previous) \
		"representative" $block(representative) \
		"balance" $block(balance) \

	# Determine database backend and access information
	set database_config  [dict get $::nano::node::configuration "node" "database"]
	set database_backend [dict get $database_config "backend"]
	if {![dict exists $database_config "configDirectory"]} {
		dict set database_config "configDirectory" $info(-configDirectory)
	}

	set dbHandle [::nano::ledger::${database_backend}::init $database_config]
	::nano::node::setLedgerHandle $dbHandle
#	set dbHandle [::nano::ledger::${database_backend}::init $database_config]
#	::nano::node::setLedgerHandle $dbHandle
}

proc ::nano::node::log {message {level "debug"}} {
	set linePrefix ""
	foreach line [split $message "\n"] {
		puts stderr [format {%-40s %10s [%5s] %s} [::info coroutine] [clock seconds] $level ${linePrefix}$line]
		set linePrefix "    "
	}
}

proc ::nano::network::client::bulk_pull {account {end ""}} {
	set accountPubKey [::nano::address::toPublicKey $account -binary]

	if {$end ne ""} {
		if {[string length $end] != $::nano::block::hashLength} {
			set end [binary decode hex $end]
		}
	} else {
		set end [binary decode hex $::nano::block::zero]
	}

	return [binary format a32a32 \
		$accountPubKey \
		$end \
	]
}

proc ::nano::network::client::frontier_req {{startAccount ""} {age ""} {count ""}} {
	if {$startAccount eq ""} {
		set accountPubKey [binary decode hex $::nano::address::zero]
	} else {
		set accountPubKey [::nano::address::toPublicKey $startAccount -binary]
	}

	if {$age eq ""} {
		set age [expr {2**32-1}]
	}

	if {$count eq ""} {
		set count [expr {2**32-1}]
	}

	return [binary format a32ii $accountPubKey $age $count]
}

proc ::nano::network::client::keepalive {} {
	# Encode our local IP address in the packet
	set localIPs [list]
	foreach ipVersion {v4 v6} {
		## XXX:TODO: Work out a better system for determining ones own IP
		switch -exact -- $ipVersion {
			v4 {
				if {![info exists ::nano::network::client::localIP(v4)]} {
					set ::nano::network::client::localIP(v4) [exec curl -sS http://ipv4.rkeene.org/whatismyip]
				}
				set localIP "::ffff:${::nano::network::client::localIP(v4)}"
			}
			v6 {
				if {![info exists ::nano::network::client::localIP(v6)]} {
					set ::nano::network::client::localIP(v6) [exec curl -sS http://ipv6.rkeene.org/whatismyip]
				}
				set localIP $::nano::network::client::localIP(v6)
			}
		}
		lappend localIPs [binary decode hex [string map [list ":" ""] [::ip::normalize $localIP]]]
	}

	# Encode port as a 16-bit integer in network byte order (big endian)
	set localPort [dict get $::nano::node::configuration "node" "peering_port"]
	set localPort [binary format s $localPort]

	set retval ""
	while {[string length $retval] < 144} {
		foreach localIP $localIPs {
			append retval "${localIP}${localPort}"
		}
	}

	return [string range $retval 0 143]
}

proc ::nano::network::client {sock messageType args} {
	set versionUsing 12
	set versionMin 1
	set versionMax 12
	set extensions 0

	set messageType [string tolower $messageType]
	set messageTypeID [lsearch -exact $::nano::network::messageTypes $messageType]
	if {$messageTypeID == -1} {
		return -code error "Invalid message type: $messageType"
	}

	set blockType 0
	set extensions [expr {$extensions | (($blockType << 8) & 0x0f00)}]

	set message [binary format a2ccccS \
		RC \
		$versionMax \
		$versionUsing \
		$versionMin \
		$messageTypeID \
		$extensions \
	]

	append message [::nano::network::client::${messageType} {*}$args]

	::nano::node::log "Sending message [binary encode hex $message] to socket $sock"

	catch {
		if {[dict get $sock "type"] eq "p2p"} {
			set sockInfo $sock
			set sock [dict get $sock "socket"]
		}
	}

	if {[info exists sockInfo]} {
		fconfigure $sock -remote [dict get $sockInfo "remote"]
	}

	chan configure $sock -translation binary -encoding binary

	puts -nonewline $sock $message
	flush $sock

	return ""
}

proc ::nano::node::bootstrap::peer {peer peerPort} {
	::nano::node::log "Connecting to ${peer}:${peerPort}"

	catch {
		set sock [::nano::network::_connect $peer $peerPort]
	} err
	if {![info exists sock]} {
		::nano::node::log "Failed to connect to ${peer} ${peerPort}: $::errorInfo"

		return
	}
	defer::defer close $sock

	::nano::node::log "Connected to $peer:$peerPort ;; sock = $sock"

	::nano::network::client $sock "frontier_req"
	while true {
		set account [::nano::address::fromPublicKey [::nano::network::_recv $sock 32]]
		set frontier [::nano::network::_recv $sock 32]

		puts "$account - [binary encode hex $frontier]"
	}

	# XXX:TODO: Pull in some stuff
	# XXX:TODO: When that stuff is pulled, add it to the ledger

	return

	::nano::network::client $sock "bulk_pull" "xrb_3h57qc7u84uz96ox3suo6wz5hz17oi7e6bpgeg3sdkayn31ujxedkjp6i1kp"
	if {[catch {
		set result [::nano::network::_recv $sock 8]
		puts "result=[binary encode hex $result]"
exit 0
	} err]} {
		::nano::node::log "Error: $err"
	}

}

proc ::nano::network::_dns::toIPList {name} {
	if {[::ip::version $name] > 0} {
		return [list $name]
	}

	set retval [list]
	foreach addressType {A AAAA} {
		set dnsQueryID [::dns::resolve $name -type $addressType]
		for {set dnsCheck 0} {$dnsCheck < 100} {incr dnsCheck} {
			switch -- [::dns::status $dnsQueryID] {
				"ok" {
					lappend retval {*}[::dns::address $dnsQueryID]

					break
				}
				"error" - "timeout" - "eof" {
					break
				}
				default {
				}
			}
			::nano::node::_sleep 10
		}
		::dns::cleanup $dnsQueryID
	}

	return $retval
}

# XXX:TODO: Which namespace should this go in ?
proc ::nano::node::_randomSortList {args} {
	set list [lindex $args end]
	set args [lrange $args 0 end-1]
	set salt [expr {rand()}]
	tailcall lsort {*}$args -command [list apply {{salt a b} {
		if {$a eq $b} {
			return 0
		}
		set a [binary encode hex [::nano::internal::hashData "${salt}|${a}"]]
		set b [binary encode hex [::nano::internal::hashData "${salt}|${b}"]]
		set a "0x${a}"
		set b "0x${b}"
		if {$a < $b} {
			return -1
		} else {
			return 1
		}
	}} $salt] $list
}

proc ::nano::node::bootstrap {} {
	while true {
		set peerInfoList [::nano::network::getPeers]
		::nano::node::log "Have [llength $peerInfoList] peers"

		foreach peerInfo $peerInfoList {
			set peer     [dict get $peerInfo "address"]
			set peerPort [dict get $peerInfo "port"]

dict set ::nano::node::configuration node bootstrap_connections 1
			if {[llength [info command ::nano::node::bootstrap::peer_*]] >= [dict get $::nano::node::configuration node bootstrap_connections]} {
				continue
			}

			set peerId [binary encode hex [::nano::internal::hashData "$peer:$peerPort" 5]]

			if {[info command ::nano::node::bootstrap::peer_${peerId}] ne ""} {
				continue
			}

			coroutine ::nano::node::bootstrap::peer_${peerId} ::nano::node::bootstrap::peer $peer $peerPort
		}

		::nano::node::_sleep 30000
	}
}

proc ::nano::network::_connect {host port} {
	if {[info coroutine] eq ""} {
		set sock [socket $host $port]
	} else {
		set sock [socket -async $host $port]
		chan event $sock writable [info coroutine]
		chan event $sock readable [info coroutine]

		if {![chan configure $sock -connecting]} {
			if {[chan configure $sock -error] ne ""} {
				close $sock

				return -code error "Socket error connecting to $host $port"
			}

			chan event $sock writable ""
			chan event $sock readable ""

			return $sock
		}

		::nano::node::log "Waiting in the event loop for socket $sock to become readable"
		yield

		chan event $sock writable ""
		chan event $sock readable ""

		if {[eof $sock] || (![chan configure $sock -connecting] && [chan configure $sock -error] ne "") || [chan configure $sock -connecting]} {
			close $sock

			return -code error "EOF from socket"
		}
	}

	chan configure $sock -blocking false -translation binary -encoding binary

	return $sock
}

proc ::nano::network::_recv {sock bytes} {
	if {[info coroutine] ne ""} {
		chan event $sock readable [info coroutine]
	}

	set retBuffer ""

	while {$bytes > 0} {
		if {[info coroutine] ne ""} {
			yield
		}

		set buffer [read $sock $bytes]
		set bufferLen [string length $buffer]
		if {$bufferLen == 0} {
			set chanError [chan configure $sock -error]
			if {$chanError ne ""} {
				return -code error "Short read on socket $sock ($bytes bytes remaining): $chanError"
			}

			continue
		}

		incr bytes -$bufferLen
		append retBuffer $buffer
	}

	chan event $sock readable ""

	return $retBuffer
}

proc ::nano::node::_sleep {ms} {
	::nano::node::log "Sleeping for $ms ms"

	after $ms [info coroutine]
	yield
}

proc ::nano::network::getPeers {} {
	if {[info exists ::nano::node::configuration]} {
		set peers [dict get $::nano::node::configuration node preconfigured_peers]
		set defaultPeerPort [dict get $::nano::node::configuration node peering_port]
	} else {
		error "Running without the node is currently unsupported"
	}

	set completePeers [list]
	foreach peer $peers {
		catch {
			foreach peer [::nano::network::_dns::toIPList $peer] {
				lappend completePeers [dict create address $peer port $defaultPeerPort]
			}
		}
	}

	set now [clock seconds]
	foreach {peerKeyInfo peerInfo} [array get ::nano::node::peers] {
		set lastSeen [dict get $peerInfo "lastSeen"]
		if {($now - $lastSeen) > (2 * 60 * 60)} {
			continue
		}

		set address [dict get $peerKeyInfo "address"]
		set peerPort [dict get $peerKeyInfo "port"]

		lappend completePeers [dict create address $peer port $peerPort]
	}

	set completePeers [::nano::node::_randomSortList -unique $completePeers]
	set retval [list]
	foreach peer $completePeers {
		lappend retval $peer
	}

	return $retval
}

proc ::nano::network::server::keepalive {blockData} {
	set peers [list]
	while {$blockData ne ""} {
		# Parse an address and port pair
		set foundElements [binary scan $blockData H32s address port]
		if {$foundElements != 2} {
			break
		}

		# Remove the parsed portion
		set blockData [string range $blockData 18 end]

		# Convert the hex-notation to an IPv6 address
		set address [string trim [regsub -all {....} $address {&:}] ":"]
		set address [::ip::contract $address]
		if {[string match "::ffff:*" $address] && [llength [split $address :]] == 5} {
			# Convert IPv4 addresses to dotted quad notation
			set address [::ip::normalize $address]
			set address [split $address :]
			set address [join [lrange $address end-1 end] ""]
			set address [::ip::intToString 0x$address]
		}
		set port [expr {$port & 0xffff}]

		lappend peers [dict create "address" $address "port" $port]
	}

	if {$blockData ne ""} {
		return -code error "Invalid keepalive packet [binary encode hex $blockData]: Had extra bytes"
	}

	if {[llength $peers] != 8} {
		return -code error "Invalid keepalive packet [binary encode hex $blockData]: Did not contain exactly 8 address+port tuples"
	}

	return [dict create "peers" $peers]
}

proc ::nano::node::server::keepalive {blockData} {
	set now [clock seconds]

	set peers [dict get [::nano::network::server::keepalive $blockData] "peers"]

	foreach peer $peers {
		set address [dict get $peer "address"]
		set port [dict get $peer "port"]

		set ::nano::node::peers([dict create address $address port $port]) [dict create lastSeen $now]
	}
}

proc ::nano::network::server::publish {blockData} {
	#puts "block: [binary encode hex $blockData]"
#9e1272edade3c247c738a4bd303eb0cfc3da298444bb9d13b8ffbced34ff036f4e1ff833324efc81c237776242928ef76a2cdfaa53f4c4530ee39bfff1977e26e382dd09ec8cafc2427cf817e9afe1f372ce81085ab4feb1f3de1f25ee818e5d000000008fc492fd20e57d048e000000204e7a62f25df739eaa224d403cb107b3f9caa0280113b0328fad3b402c465169006f988549a8b1e20e0a09b4b4dcae5397f6fcc4d507675f58c2b29ae02341b0a4fe562201a61bf27481aa4567c287136b4fd26b4840c93c42c7d1f5c518503d68ec561af4b8cf8
#9e1272edade3c247c738a4bd303eb0cfc3da298444bb9d13b8ffbced34ff036fa5e3647d3d296ec72baea013ba7fa1bf5c3357c33c90196f078ba091295e6e03e382dd09ec8cafc2427cf817e9afe1f372ce81085ab4feb1f3de1f25ee818e5d000000008fb2604ebd1fe098b8000000204e7a62f25df739eaa224d403cb107b3f9caa0280113b0328fad3b402c465165287cd9c61752dc9d011f666534dbdc10461e927503f9599791d73b1cca7fdc032d76db3f91e5b5c3d6206fa48b01bd08da4a89f2e880242e9917cfc3db80d0b9bfe8e6d1dd183d5
}

proc ::nano::network::server {message {networkType "bootstrap"}} {
	set message [binary scan $message a2ccccsa* \
		packetMagic \
		versionMax \
		versionUsing \
		versionMin \
		messageTypeID \
		extensions \
		args
	]

	if {$packetMagic ne "RC"} {
		return ""
	}

	# XXX:TODO: Check versions and extensions

	set messageType [lindex $::nano::network::messageTypes $messageTypeID]

	set retval ""
	if {[catch {
		set retval [::nano::node::server::${messageType} $args]
	} err]} {
		if {![string match "invalid command name *" $err]} {
			::nano::node::log "Error handling ${messageType}: $err"
		}
	}

	return $retval
}

proc ::nano::node::p2p::incoming {socket} {
	set data [read $socket 8192]
	if {$data eq ""} {
		return
	}

	set remote [chan configure $socket -peer]
	set response [::nano::network::server $data "p2p"]
	if {$response eq ""} {
		return
	}

	# XXX:TODO: Send response
	set peerSock [list type "p2p" remote $remote socket $socket]
	#::nano::network::client $peerSock ...

	return
}

proc ::nano::node::p2p {} {
	package require udp

	set peeringPort [dict get $::nano::node::configuration node peering_port]

	# Start a UDP listening socket
	set socket(v6) [udp_open $peeringPort ipv6 reuse]
	set socket(v4) [udp_open $peeringPort reuse]
	foreach {protocolVersion protocolSocket} [array get socket] {
		fconfigure $protocolSocket -blocking false -encoding binary -translation binary
		chan event $protocolSocket readable [list ::nano::node::p2p::incoming $protocolSocket]
	}

	# Periodically send keepalives to all known peers
	## XXX:TODO: Limit this to only a few peers
	while true {
		foreach peerInfo [::nano::network::getPeers] {
			set peerAddress [dict get $peerInfo "address"]
			set peerPort [dict get $peerInfo "port"]
			set protocolVersion "v[::ip::version $peerAddress]"

			set peerSock [list type "p2p" remote [list $peerAddress $peerPort] socket $socket(${protocolVersion})]

			::nano::network::client $peerSock "keepalive"
		}

		::nano::node::_sleep [expr {5 * 60 * 1000}]
	}
}

proc ::nano::node::start {} {
	package require defer
	package require ip
	package require udp
	package require dns

	coroutine ::nano::node::bootstrap::run ::nano::node::bootstrap
	coroutine ::nano::node::p2p::run ::nano::node::p2p

	vwait ::nano::node::_FOREVER_
}

# RPC Client
## Side-effect: Sets ::nano::rpc::client::config
proc ::nano::rpc::client::init args {
	if {![info exists ::nano::rpc::client::config]} {
		set ::nano::rpc::client::config [dict create \

	set data [json::json2dict $data]

	return $data
}

# Account balance manipulation
set ::nano::balance::_conversion {
	GNano 1000000000000000000000000000000000000000
	MNano 1000000000000000000000000000000000000
	Gnano 1000000000000000000000000000000000
	Gxrb  1000000000000000000000000000000000
	KNano 1000000000000000000000000000000000
	Nano  1000000000000000000000000000000
	_USER 1000000000000000000000000000000
	NANO  1000000000000000000000000000000
	Mnano 1000000000000000000000000000000
	Mxrb  1000000000000000000000000000000
	Mrai  1000000000000000000000000000000
	knano 1000000000000000000000000000
	kxrb  1000000000000000000000000000
	mNano 1000000000000000000000000000
	nano  1000000000000000000000000
	xrb   1000000000000000000000000
	uNano 1000000000000000000000000
	mnano 1000000000000000000000
	mxrb  1000000000000000000000
	unano 1000000000000000000
	uxrb  1000000000000000000
	Traw  1000000000000
	Graw  1000000000
	Mraw  1000000
	Kraw  1000
	raw   1
}

proc ::nano::balance::toUnit {raw toUnit {decimals 0}} {
	set divisor [dict get $::nano::balance::_conversion $toUnit]

	if {$decimals == 0} {
		set balance [expr {entier(($raw / ($divisor * 1.0)) + 0.5)}]
	} else {
		set balance [expr {$raw / ($divisor * 1.0)}]

	set balance [join [list $leading $trailing] "."]
	set balance [string trimright $balance "."]

	set result [list $balance $baseUnit]

	return $result
}

proc ::nano::network::_read {fd bytes} {
	if {[chan configure $fd -blocking]} {
		tailcall ::read $fd $bytes
	}

	set data ""
	while {$bytes > 0} {
		set readData [read $fd $bytes]
		if {[string length $readData] == 0} {
			if {[eof $fd]} {
				break
			} else {
				update

				continue
			}
		}

		incr bytes -[string length $readData]
		append data $readData
	}

	return $data
}