# Code for handling the kinematics of cable winch robots
#
# Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import stepper, mathutil

class WinchKinematics:
    def __init__(self, toolhead, config):
        # Setup steppers at each anchor
        self.steppers = []
        self.anchors = []
        for i in range(26):
            name = 'stepper_' + chr(ord('a') + i)
            if i >= 3 and not config.has_section(name):
                break
            stepper_config = config.getsection(name)
            s = stepper.LookupMultiRail(stepper_config)
            s.get_homing_info().position_endstop
            self.steppers.append(s)
            a = tuple([stepper_config.getfloat('anchor_' + n) for n in 'xyz'])
            self.anchors.append(a)
            s.setup_itersolve('winch_stepper_alloc', *a)
            s.set_trapq(toolhead.get_trapq())
            toolhead.register_step_generator(s.generate_steps)
        config.get_printer().register_event_handler("stepper_enable:motor_off",
                                                    self._motor_off)
        # Setup max velocity
        self.max_velocity, self.max_accel = toolhead.get_max_velocity()
        self.max_z_velocity = config.getfloat(
            'max_z_velocity', self.max_velocity,
            above=0., maxval=self.max_velocity)
        self.max_z_accel = config.getfloat('max_z_accel', self.max_accel,
                                          above=0., maxval=self.max_accel)
        # Setup boundary checks
        acoords = list(zip(*self.anchors))
        self.limits = [(1.0, -1.0)] * 3
        self.axes_min = toolhead.Coord(*[min(a) for a in acoords], e=0.)
        self.axes_max = toolhead.Coord(*[max(a) for a in acoords], e=0.)
        self.set_position([0., 0., 0.], ())
    def get_steppers(self):
        return list(self.steppers)
    def calc_position(self, stepper_positions):
        # Use only first three steppers to calculate cartesian position
        pos = [stepper_positions[rail.get_name()] for rail in self.steppers[:3]]
        return mathutil.trilateration(self.anchors[:3], [sp*sp for sp in pos])
    def set_position(self, newpos, homing_axes):
        for i, s in enumerate(self.steppers):
            s.set_position(newpos)
            if i in homing_axes:
                self.limits[i] = s.get_range()
    def note_z_not_homed(self):
        # Helper for Safe Z Home
        self.limits[2] = (1.0, -1.0)
    def home(self, homing_state):
        # Each axis is homed independently and in order
        for axis in homing_state.get_axes():
            s = self.steppers[axis]
            # Determine movement
            position_min, position_max = s.get_range()
            hi = s.get_homing_info()
            homepos = [None, None, None, None]
            homepos[axis] = hi.position_endstop
            forcepos = list(homepos)
            if hi.positive_dir:
                forcepos[axis] -= 1.5 * (position_min)
            else:
                forcepos[axis] += 1.5 * (position_max)
            # Perform homing
            homing_state.home_rails([s], forcepos, homepos)
        homing_state.set_axes([0, 1, 2])
        homing_state.set_homed_position([0., 0., 0.])
    def _check_endstops(self, move):
        end_pos = move.end_pos
        for i in (0, 1, 2):
            if (move.axes_d[i]
                and (end_pos[i] < self.limits[i][0]
                     or end_pos[i] > self.limits[i][1])):
                if self.limits[i][0] > self.limits[i][1]:
                    raise move.move_error("Must home axis first")
                raise move.move_error()
    def check_move(self, move):
        limits = self.limits
        xpos, ypos = move.end_pos[:2]
        if (xpos < limits[0][0] or xpos > limits[0][1]
            or ypos < limits[1][0] or ypos > limits[1][1]):
            self._check_endstops(move)
        if not move.axes_d[2]:
            # Normal XY move - use defaults
            return
        # Move with Z - update velocity and accel for slower Z axis
        self._check_endstops(move)
        z_ratio = move.move_d / abs(move.axes_d[2])
        move.limit_speed(
            self.max_z_velocity * z_ratio, self.max_z_accel * z_ratio)
    def _motor_off(self, print_time):
        self.limits = [(1.0, -1.0)] * 3
    def get_status(self, eventtime):
        axes = [a for a, (l, h) in zip("xyz", self.limits) if l <= h]
        return {
            'homed_axes': "".join(axes),
            'axis_minimum': self.axes_min,
            'axis_maximum': self.axes_max,
        }

def load_kinematics(toolhead, config):
    return WinchKinematics(toolhead, config)