module Knot
	class Error < ::Exception
		attr_reader :Errno
		attr_reader :Key
		attr_reader :Errstr
	end
end

module Knot::Errors
	@num2exc = {}
	@key2exc = {}
	@err2exc = {}
	class << self
		attr_reader :num2exc, :key2exc, :err2exc

		def array_arguments_with_typecheck *args
			l = args.length
			lambda do |a|
				l == a.length and
					args.zip(a).all? {|t,v| t === v }
			end
		end
	end

	def method_missing key
		self[key]
	end

	def [] key_or_errno
		case key_or_errno
		when Integer
			@num2exc[key_or_errno]
		when Exception
			key_or_errno
		when Symbol
			@key2exc[key_or_errno]
		else
			raise ArgumentError, "Invalid type. Expect Integer/Knot::Error/Symbol"
		end
	end

	i = 0
	[
		[:EOK,            0,                            "OK"],
		# Directly mapped error codes.
		[:ENOMEM,         -Errno::ENOMEM::Errno,        "not enough memory" ],
		[:EINVAL,         -Errno::EINVAL::Errno,        "invalid parameter" ],
		[:ENOTSUP,        -Errno::ENOTSUP::Errno,       "operation not supported" ],
		[:EBUSY,          -Errno::EBUSY::Errno,         "requested resource is busy" ],
		[:EAGAIN,         -Errno::EAGAIN::Errno,        "OS lacked necessary resources" ],
		[:EACCES,         -Errno::EACCES::Errno,        "operation not permitted" ],
		[:ECONNREFUSED,   -Errno::ECONNREFUSED::Errno,  "connection refused" ],
		[:EISCONN,        -Errno::EISCONN::Errno,       "already connected" ],
		[:EADDRINUSE,     -Errno::EADDRINUSE::Errno,    "address already in use" ],
		[:ENOENT,         -Errno::ENOENT::Errno,        "not exists" ],
		[:EEXIST,         -Errno::EEXIST::Errno,        "already exists" ],
		[:ERANGE,         -Errno::ERANGE::Errno,        "value is out of range" ],
		[:EADDRNOTAVAIL,  -Errno::EADDRNOTAVAIL::Errno, "address is not available" ],

		# General errors.
		[:ERROR,           -1000, "failed"],
		[:EPARSEFAIL,             "parser failed"],
		[:ESEMCHECK,              "semantic check"],
		[:EUPTODATE,              "zone is up-to-date"],
		[:EFEWDATA,               "not enough data to parse"],
		[:ESPACE,                 "not enough space provided"],
		[:EMALF,                  "malformed data"],
		[:ENSEC3PAR,              "missing or wrong NSEC3PARAM record"],
		[:ENSEC3CHAIN,            "missing or wrong NSEC3 chain in the zone"],
		[:EOUTOFZONE,             "name does not belong to the zone"],
		[:EZONEINVAL,             "invalid zone file"],
		[:ENOZONE,                "no such zone found"],
		[:ENONODE,                "no such node in zone found"],
		[:ENORECORD,              "no such record in zone found"],
		[:EISRECORD,              "such record already exists in zone"],
		[:ENOMASTER,              "no usable master"],
		[:EPREREQ,                "UPDATE prerequisity not met"],
		[:ETTL,                   "TTL mismatch"],
		[:ENOXFR,                 "transfer was not sent"],
		[:EDENIED,                "not allowed"],
		[:ECONN,                  "connection reset"],
		[:ETIMEOUT,               "connection timeout"],
		[:ENODIFF,                "cannot create zone diff"],
		[:ENOTSIG,                "expected a TSIG or SIG(0)"],
		[:ELIMIT,                 "exceeded response rate limit"],
		[:EZONESIZE,              "zone size exceeded"],
		[:EOF,                    "end of file"],
		[:ESYSTEM,                "system error"],
		[:EFILE,                  "file error"],
		[:ESOAINVAL,              "SOA mismatch"],
		[:ETRAIL,                 "trailing data"],
		[:EPROCESSING,            "processing error"],

		# Control states.
		[:CTL_ESTOP,              "stopping server"],
		# Network errors.
		[:NET_EADDR,              "bad address or host name"],
		[:NET_ESOCKET,            "can't create socket"],
		[:NET_ECONNECT,           "can't connect"],
		[:NET_ESEND,              "can't send data"],
		[:NET_ERECV,              "can't receive data"],
		[:NET_ETIMEOUT,           "network timeout"],
		# Encoding errors.
		[:BASE64_ESIZE,           "invalid base64 string length"],
		[:BASE64_ECHAR,           "invalid base64 character"],
		[:BASE32HEX_ESIZE,        "invalid base32hex string length"],
		[:BASE32HEX_ECHAR,        "invalid base32hex character"],
		# TSIG errors.
		[:KNOT_TSIG_EBADSIG,      "failed to verify TSIG"],
		[:KNOT_TSIG_EBADKEY,      "TSIG key not recognized or invalid"],
		[:KNOT_TSIG_EBADTIME,     "TSIG out of time window"],
		[:KNOT_TSIG_EBADTRUNC,    "TSIG bad truncation"],
		# DNSSEC errors.
		[:DNSSEC_ENOKEY,          "no keys for signing"],
		[:DNSSEC_EMISSINGKEYTYPE, "missing active KSK or ZSK"],
		# Yparser errors.
		[:YP_ECHAR_TAB,           "tabulator character is not allowed"],
		[:YP_EINVAL_ITEM,         "invalid item"],
		[:YP_EINVAL_ID,           "invalid identifier"],
		[:YP_EINVAL_DATA,         "invalid value"],
		[:YP_EINVAL_INDENT,       "invalid indentation"],
		[:YP_ENOTSUP_DATA,        "value not supported"],
		[:YP_ENOTSUP_ID,          "identifier not supported"],
		[:YP_ENODATA,             "missing value"],
		[:YP_ENOID,               "missing identifier"],
		# Configuration errors.
		[:CONF_ENOTINIT,          "config DB not initialized"],
		[:CONF_EVERSION,          "invalid config DB version"],
		[:CONF_EREDEFINE,         "duplicate identifier"],
		# Transaction errors.
		[:TXN_EEXISTS,            "too many transactions"],
		[:TXN_ENOTEXISTS,         "no active transaction"],
		# DNSSEC errors.
		[:INVALID_PUBLIC_KEY,     "invalid public key"],
		[:INVALID_PRIVATE_KEY,    "invalid private key"],
		[:INVALID_KEY_ALGORITHM,  "invalid key algorithm"],
		[:INVALID_KEY_SIZE,       "invalid key size"],
		[:INVALID_KEY_ID,         "invalid key ID"],
		[:INVALID_KEY_NAME,       "invalid key name"],
		[:NO_PUBLIC_KEY,          "no public key"],
		[:NO_PRIVATE_KEY,         "no private key"],
	].each do |v|
		e = nil
		case v
		when array_arguments_with_typecheck( Symbol, String)
			v, e = v
		when array_arguments_with_typecheck( String, String)
			v, e = v
			v = v.to_sym
		when array_arguments_with_typecheck( Symbol, Integer, String)
			v, i, e = v
		when array_arguments_with_typecheck( String, Integer, String)
			v, i, e = v
			v = v.to_sym
		else
			raise ArgumentError, "[Symbol, String] | [Symbol, Int, String] expected, not #{v}"
		end
		cl = Class.new Exception
		cl.const_set :Key, v
		cl.const_set :Errno, i
		cl.const_set :Errstr, e
		const_set v, cl
		@num2exc[i] = @key2exc[v] = @err2exc[e] = cl
		i += 1
	end
end