# X-Plane Remote Access client module
#-------------------------------------------------------------------------------

import os
import struct
import array

#-------------------------------------------------------------------------------

COMMAND_GET_SINGLE = 0x01

COMMAND_SET_SINGLE = 0x02

COMMAND_GET_MULTI = 0x03

COMMAND_SET_MULTI = 0x04

COMMAND_REGISTER_GET_MULTI = 0x11

COMMAND_UNREGISTER_GET_MULTI = 0x12

COMMAND_EXECUTE_GET_MULTI = 0x13

COMMAND_REGISTER_SET_MULTI = 0x21

COMMAND_UNREGISTER_SET_MULTI = 0x22

COMMAND_EXECUTE_SET_MULTI = 0x23

TYPE_INT = 0x01

TYPE_FLOAT = 0x02

TYPE_DOUBLE = 0x03

TYPE_FLOAT_ARRAY = 0x11

TYPE_INT_ARRAY = 0x12

TYPE_BYTE_ARRAY = 0x13

RESULT_OK = 0x00

RESULT_INVALID_COMMAND = 0x01

RESULT_UNKNOWN_DATAREF = 0x02

RESULT_INVALID_TYPE = 0x03

RESULT_INVALID_LENGTH = 0x04

RESULT_INVALID_OFFSET = 0x05

RESULT_INVALID_COUNT = 0x06

RESULT_INVALID_ID = 0x07

RESULT_OTHER_ERROR = 0xff

#-------------------------------------------------------------------------------

class ProtocolException(Exception):
    """Exception to signify protocol errors."""
    _message = { RESULT_INVALID_COMMAND : "invalid command",
                 RESULT_UNKNOWN_DATAREF : "unknown dataref",
                 RESULT_INVALID_TYPE : "invalid type",
                 RESULT_INVALID_LENGTH : "invalid length",
                 RESULT_INVALID_OFFSET : "invalid offset",
                 RESULT_INVALID_COUNT : "invalid count",
                 RESULT_INVALID_ID : "invalid ID",
                 RESULT_OTHER_ERROR : "other error" }

    @staticmethod
    def getMessage(resultCode):
        """Get the message for the given result code."""
        if resultCode in ProtocolException._message:
            return ProtocolException._message[resultCode]
        else:
            return "unknown error code " + `resultCode`

    def __init__(self, resultCode):
        super(ProtocolException, self).__init__("xplra.ProtocolException: " +
                                                self.getMessage(resultCode))
        self.resultCode = resultCode

#-------------------------------------------------------------------------------

class XPlane(object):
    """The main class representing the connection to X-Plane."""

    @staticmethod
    def _packLength(x):
        """Pack the given integer as a variable-length value."""
        s = ""
        while True:
            y = x&0x7f
            x >>= 7
            if x>0: y |= 0x80
            s += struct.pack("B", y)
            if x==0:
                return s

    @staticmethod
    def _packString(s):
        """Pack the given string."""
        return XPlane._packLength(len(s)) + s

    def __init__(self):
        """Construct the object."""
        self._stream = None

    def connect(self):
        """Try to connect to X-Plane."""
        if self._stream is not None:
            return

        if os.name=="nt":
            self._stream = open(r'\\.\pipe\\xplra', "b")
        else:
            import socket
            s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
            s.connect("/tmp/xplra-" + os.environ["LOGNAME"])
            self._stream = s.makefile()

    @property
    def isConnected(self):
        """Determine if we are connected to the simulator."""
        return self._stream is not None

    def getInt(self, name):
        """Get the value of the integer dataref with the given name."""
        return self._getSingle(name, TYPE_INT)

    def getFloat(self, name):
        """Get the value of the float dataref with the given name."""
        return self._getSingle(name, TYPE_FLOAT)

    def getDouble(self, name):
        """Get the value of the double dataref with the given name."""
        return self._getSingle(name, TYPE_DOUBLE)

    def getFloatArray(self, name, length = -1, offset = 0):
        """Get the value of the float array dataref with the given name."""
        return self._getSingle(name, TYPE_FLOAT_ARRAY, length, offset)

    def getIntArray(self, name, length = -1, offset = 0):
        """Get the value of the integer array dataref with the given name."""
        return self._getSingle(name, TYPE_INT_ARRAY, length, offset)

    def getByteArray(self, name, length = -1, offset = 0):
        """Get the value of the byte array dataref with the given name."""
        return self._getSingle(name, TYPE_BYTE_ARRAY, length, offset)

    def getString(self, name, offset = 0):
        """Get the value of the byte array dataref with the given name as a
        string."""
        return self.getByteArray(name, offset = offset).tostring()

    def disconnect(self):
        """Disconnect from X-Plane."""
        if self._stream is not None:
            self._stream.close()
            self._stream = None

    def _checkResult(self, resultCode = None):
        """Check the given result code.

        If it is None, it will be read first.

        If it is not RESULT_OK, a ProtocolException is thrown."""

        if resultCode is None:
            resultCode = self._readU8()
        if resultCode!=RESULT_OK:
            raise ProtocolException(resultCode)

    def _getSingle(self, name, type, length = None, offset = None):
        """Get the single value of the given name and type."""
        self._writeU8(COMMAND_GET_SINGLE)
        self._writeString(name)
        self._writeU8(type)
        if length is not None and offset is not None:
            self._writeS32(length)
            self._writeS32(offset)

        self._flush()
        self._checkResult()
        return self._readValue(type)

    def _readValue(self, type):
        """Read the value of the given type from the stream."""
        if type==TYPE_INT:
            return self._readS32()
        elif type==TYPE_FLOAT:
            return self._readFloat()
        elif type==TYPE_DOUBLE:
            return self._readDouble()
        else:
            length = self._readS32()
            arr = None
            elementSize = 4
            if type==TYPE_FLOAT_ARRAY:
                arr = array.array("f")
            elif type==TYPE_INT_ARRAY:
                arr = array.array("i")
            elif type==TYPE_BYTE_ARRAY:
                arr = array.array("B")
                elementSize = 1
            if arr is not None and length>0:
                arr.fromstring(self._stream.read(length*elementSize))
            return arr

    def _writeU8(self, x):
        """Write the given value as an unsigned, 8-bit value."""
        self._stream.write(struct.pack("B", x))

    def _writeS32(self, x):
        """Write the given value as a signed, 32-bit value."""
        self._stream.write(struct.pack("i", x))

    def _writeU32(self, x):
        """Write the given value as an unsigned, 32-bit value."""
        self._stream.write(struct.pack("I", x))

    def _writeFloat(self, x):
        """Write the given value as a single-precision floating point."""
        self._stream.write(struct.pack("f", x))

    def _writeDouble(self, x):
        """Write the given value as a double-precision floating point."""
        self._stream.write(struct.pack("d", x))

    def _writeLength(self, length):
        """Write the given value is a variable-length value into our stream."""
        self._stream.write(self._packLength(length))

    def _writeString(self, str):
        """Write the given string into the stream."""
        self._stream.write(self._packString(str))

    def _flush(self):
        """Flush our stream."""
        self._stream.flush()

    def _readU8(self):
        """Read an unsigned, 8-bit value from the stream."""
        (value,) = struct.unpack("B", self._stream.read(1))
        return value

    def _readS32(self):
        """Read a signed, 32-bit value from the stream."""
        (value,) = struct.unpack("i", self._stream.read(4))
        return value

    def _readU32(self):
        """Read an unsigned, 32-bit value from the stream."""
        (value,) = struct.unpack("I", self._stream.read(4))
        return value

    def _readFloat(self):
        """Read a single-precision floating point value from the stream."""
        (value,) = struct.unpack("f", self._stream.read(4))
        return value

    def _readDouble(self):
        """Read a double-precision floating point value from the stream."""
        (value,) = struct.unpack("d", self._stream.read(8))
        return value

    def _readLength(self):
        """Read a variable-length value from our stream."""
        length = 0
        while True:
            (x,) = struct.unpack("B", self._stream.read(1))
            length <<= 7
            length |= x&0x7f
            if x&0x80==0:
                return length

    def _readString(self):
        """Read a string from our stream."""
        length = self._readLength()
        return self._stream.read(length)

#-------------------------------------------------------------------------------