from bbctrl.Comm import Comm
import bbctrl
import bbctrl.Cmd as Cmd

# Axis homing procedure:
#
#   Mark axis unhomed
#   Set feed rate to search_vel
#   Seek closed by search_dist
#   Set feed rate to latch_vel
#   Seek open latch_backoff
#   Seek closed latch_backoff * -1.5
#   Rapid to zero_backoff
#   Mark axis homed and set absolute position

axis_homing_procedure = '''
  G28.2 %(axis)s0 F[#<_%(axis)s_search_velocity>]
  G38.6 %(axis)s[#<_%(axis)s_home_travel>]
  G38.8 %(axis)s[#<_%(axis)s_latch_backoff>] F[#<_%(axis)s_latch_velocity>]
  G38.6 %(axis)s[#<_%(axis)s_latch_backoff> * -8]
  G91 G0 G53 %(axis)s[#<_%(axis)s_zero_backoff>]
  G90 G28.3 %(axis)s[#<_%(axis)s_home_position>]
'''

# The stepper drivers have a stall flag that is reset
# by moving the motors without a stall condition.
# The "wiggle" in the stall procedure is to clear the flag.
# This was to correct the issue where the stepper motors
# may already be in a stall condition when homing is started.
# For example, if a user tried to home twice in a row
# the second homing attempt would immediately think it
# was stalled if we didn't first back it up a bit
stall_homing_procedure = '''
  G91 G1 %(axis)s [#<_%(axis)s_zero_backoff>] F[#<_%(axis)s_search_velocity>]
  G4 P0.25
  G28.2 %(axis)s0 F[#<_%(axis)s_search_velocity>]
  G38.6 %(axis)s[#<_%(axis)s_home_travel>]
  G91 G1 G53 %(axis)s[#<_%(axis)s_zero_backoff>] F100
  G90 G28.3 %(axis)s[#<_%(axis)s_home_position>]
'''

motor_fault_error = '''\
Motor %d driver fault.  A potentially damaging electrical condition was \
detected and the motor driver was shutdown.  Please power down the controller \
and check your motor cabling. See the "Motor Faults" table on the "Indicators" \
for more information.\
'''


def overrides(interface_class):

    def overrider(method):
        if not method.__name__ in dir(interface_class):
            raise Exception('%s does not override %s' %
                            (method.__name__, interface_class.__name__))

        return method

    return overrider


class Mach(Comm):

    def __init__(self, ctrl, avr):
        super().__init__(ctrl, avr)

        self.ctrl = ctrl
        self.mlog = self.ctrl.log.get('Mach')

        self.planner = bbctrl.Planner(ctrl)
        self.unpausing = False
        self.stopping = False

        ctrl.state.set('cycle', 'idle')

        ctrl.state.add_listener(self._update)

        super().reboot()

    def _get_state(self):
        return self.ctrl.state.get('xx', '')

    def _is_estopped(self):
        return self._get_state() == 'ESTOPPED'

    def _is_holding(self):
        return self._get_state() == 'HOLDING'

    def _is_ready(self):
        return self._get_state() == 'READY'

    def _get_pause_reason(self):
        return self.ctrl.state.get('pr', '')

    def _get_cycle(self):
        return self.ctrl.state.get('cycle', 'idle')

    def _is_paused(self):
        if not self._is_holding() or self.unpausing:
            return False
        return self._get_pause_reason() in ('User pause', 'Program pause',
                                            'Optional pause')

    def _set_cycle(self, cycle):
        self.ctrl.state.set('cycle', cycle)

    def _begin_cycle(self, cycle):
        current = self._get_cycle()
        if current == cycle:
            return  # No change

        if current != 'idle':
            raise Exception('Cannot enter %s cycle while in %s cycle' %
                            (cycle, current))

        # TODO handle jogging during pause
        # if current == 'idle' or (cycle == 'jogging' and self._is_paused()):
        self._set_cycle(cycle)

    def process_log(self, log):
        # When a probe has failed, we have to e-stop or things
        # end up in a bad state, where positions and offsets are incorrect
        if log['msg'] == 'Switch not found':
            self.estop()

    def _update(self, update):
        # Detect motor faults
        for motor in range(4):
            key = '%ddf' % motor
            if key in update and update[key] & 0x1f:
                self.mlog.error(motor_fault_error % motor)

        # Get state
        state_changed = 'xc' in update
        state = self._get_state()

        # Handle EStop
        if state_changed and state == 'ESTOPPED':
            self.planner.reset(stop=False)

        # Exit cycle if state changed to READY
        if (state_changed and self._get_cycle() != 'idle' and self._is_ready()
                and not self.planner.is_busy() and not super().is_active()):
            self.planner.position_change()
            self._set_cycle('idle')

        # Planner stop
        if state == 'READY' and self.stopping:
            self.planner.stop()
            self.ctrl.state.set('line', 0)
            self.stopping = False

        # Unpause sync
        if state_changed and state != 'HOLDING':
            self.unpausing = False

        # Entering HOLDING state
        if state_changed and state == 'HOLDING':
            # Always flush queue after pause
            super().i2c_command(Cmd.FLUSH)
            super().resume()

        # Automatically unpause after seek or stop hold
        # Must be after holding commands above
        op = self.ctrl.state.get('optional_pause', False)
        pr = self._get_pause_reason()
        if ((state_changed or 'pr' in update) and self._is_holding()
                and (pr in ('Switch found', 'User stop') or
                     (pr == 'Optional pause' and not op))):
            self._unpause()

    def _unpause(self):
        pause_reason = self._get_pause_reason()
        self.mlog.info('Unpause: ' + pause_reason)

        if pause_reason == 'User stop':
            self.planner.stop()
            self.ctrl.state.set('line', 0)

        else:
            self.planner.restart()

        super().i2c_command(Cmd.UNPAUSE)
        self.unpausing = True

    def _i2c_block(self, block):
        super().i2c_command(block[0], block=block[1:])

    def _i2c_set(self, name, value):
        self._i2c_block(Cmd.set(name, value))

    @overrides(Comm)
    def comm_next(self):
        if self.planner.is_running() and not self._is_holding():
            return self.planner.next()

    @overrides(Comm)
    def comm_error(self):
        self.planner.reset()

    @overrides(Comm)
    def connect(self):
        self.planner.reset()
        super().connect()

    def _query_var(self, cmd):
        equal = cmd.find('=')
        if equal == -1:
            self.mlog.info('%s=%s' % (cmd, self.ctrl.state.get(cmd[1:])))

        else:
            name, value = cmd[1:equal], cmd[equal + 1:]

            if value.lower() == 'true':
                value = True
            elif value.lower() == 'false':
                value = False
            else:
                try:
                    value = float(value)
                except:
                    pass

            self.ctrl.state.config(name, value)

    def mdi(self, cmd, with_limits=True):
        try:
            if not len(cmd):
                return
            if cmd[0] == '$':
                self._query_var(cmd)
            elif cmd[0] == '\\':
                super().queue_command(cmd[1:])
            else:
                self._begin_cycle('mdi')
                self.planner.mdi(cmd, with_limits)
                super().resume()
        except BaseException as err:
            self.mlog.info("Exception during MDI: %s" % err)
            pass

    def set(self, code, value):
        super().queue_command('${}={}'.format(code, value))

    def jog(self, axes):
        self._begin_cycle('jogging')
        self.planner.position_change()
        super().queue_command(Cmd.jog(axes))

    def home(self, axis, position=None):
        state = self.ctrl.state

        if axis is None:
            axes = 'zxyabc'  # TODO This should be configurable
        else:
            axes = '%c' % axis

        for axis in axes:
            enabled = state.is_axis_enabled(axis)
            mode = state.axis_homing_mode(axis)

            # If this is not a request to home a specific axis and the
            # axis is disabled or in manual homing mode, don't show any
            # warnings
            if 1 < len(axes) and (not enabled or mode == 'manual'):
                continue

            # Error when axes cannot be homed
            reason = state.axis_home_fail_reason(axis)
            if reason is not None:
                self.mlog.error('Cannot home %s axis: %s' %
                                (axis.upper(), reason))
                continue

            if mode == 'manual':
                if position is None:
                    raise Exception('Position not set')
                self.mdi('G28.3 %c%f' % (axis, position))
                continue

            # Home axis
            self.mlog.info('Homing %s axis' % axis)
            self._begin_cycle('homing')

            if mode.startswith('stall-'):
                procedure = stall_homing_procedure
            else:
                procedure = axis_homing_procedure

            gcode = procedure % {'axis': axis}

            self.planner.mdi(gcode, False)
            super().resume()

    def unhome(self, axis):
        self.mdi('G28.2 %c0' % axis)

    def estop(self):
        super().estop()

    def clear(self):
        if self._is_estopped():
            self.planner.reset()
            super().clear()

    def fake_probe_contact(self):
        self._i2c_set('pt', 2)
        self.ctrl.state.set('pw', 0)
        self.timer = self.ctrl.ioloop.call_later(0.5,
                                                 self.clear_fake_probe_contact)

    def clear_fake_probe_contact(self):
        self._i2c_set('pt', 1)
        self.ctrl.state.set('pw', 1)

    def start(self):
        filename = self.ctrl.state.get('selected', '')
        if not filename:
            return
        self._begin_cycle('running')
        self.planner.load(filename)
        super().resume()

    def step(self):
        raise Exception('NYI')  # TODO
        if self._get_cycle() != 'running':
            self.start()
        else:
            super().i2c_command(Cmd.UNPAUSE)

    def stop(self):
        if self._get_state() != 'jogging':
            self.stopping = True
        super().i2c_command(Cmd.STOP)

    def pause(self):
        super().pause()

    def unpause(self):
        if self._is_paused():
            self.ctrl.state.set('optional_pause', False)
            self._unpause()

    def optional_pause(self, enable=True):
        self.ctrl.state.set('optional_pause', enable)

    def set_position(self, axis, position):
        axis = axis.lower()
        state = self.ctrl.state

        if state.is_axis_homed(axis):
            # If homed, change the offset rather than the absolute position
            self.mdi('G92%s%f' % (axis, position))

        elif state.is_axis_enabled(axis):
            if self._get_cycle() != 'idle' and not self._is_paused():
                raise Exception('Cannot set position during ' +
                                self._get_cycle())

            # Set the absolute position both locally and via the AVR
            target = position + state.get('offset_' + axis)
            state.set(axis + 'p', target)
            super().queue_command(Cmd.set_axis(axis, target))

    def override_feed(self, override):
        self._i2c_set('fo', int(1000 * override))

    def override_speed(self, override):
        self._i2c_set('so', int(1000 * override))

    def modbus_read(self, addr):
        self._i2c_block(Cmd.modbus_read(addr))

    def modbus_write(self, addr, value):
        self._i2c_block(Cmd.modbus_write(addr, value))