# this package is part of the PyGeodesy package found here https://pypi.python.org/pypi/PyGeodesy by Jean M. Brouwers

# -*- coding: utf-8 -*-

u'''Vincenty's ellipsoidal geodetic (lat-/longitude) and cartesian (x/y/z)
classes L{LatLon}, L{Cartesian} and L{VincentyError}.

Pure Python implementation of geodesy tools for ellipsoidal earth models,
transcribed from JavaScript originals by I{(C) Chris Veness 2005-2016}
and published under the same MIT Licence**. For details see
U{http://www.movable-type.co.uk/scripts/LatLongVincenty.html} and also
U{http://github.com/geopy} and U{http://python.org/pypi/geopy}.

Calculate geodesic distance between two points using the U{Vincenty
<http://wikipedia.org/wiki/Vincenty's_formulae>} formulae and one of
several ellipsoidal earth models.  The default model is WGS-84, the
most accurate and widely used globally-applicable model for the earth
ellipsoid.

Other ellipsoids offering a better fit to the local geoid include
Airy (1830) in the UK, Clarke (1880) in Africa, International 1924
in much of Europe, and GRS-67 in South America.  North America
(NAD83) and Australia (GDA) use GRS-80, which is equivalent to the
WGS-84 model.

Great-circle distance uses a spherical model of the earth with the
mean earth radius defined by the International Union of Geodesy and
Geophysics (IUGG) as M{(2 * a + b) / 3 = 6371008.7714150598} meter or
approx. 6371009 meter (for WGS-84, resulting in an error of up to
about 0.5%).

Here's an example usage of Vincenty:

    >>> from pygeodesy.ellipsoidalVincenty import LatLon
    >>> Newport_RI = LatLon(41.49008, -71.312796)
    >>> Cleveland_OH = LatLon(41.499498, -81.695391)
    >>> Newport_RI.distanceTo(Cleveland_OH)
    866455.4329158525  # meter

You can change the ellipsoid model used by the Vincenty formulae
as follows:

    >>> from pygeodesy import Datums
    >>> from pygeodesy.ellipsoidalVincenty import LatLon
    >>> p = LatLon(0, 0, datum=Datums.OSGB36)

or by converting to anothor datum:

    >>> p = p.convertDatum(Datums.OSGB36)

@newfield example: Example, Examples
'''

from datum import Datums
from ellipsoidalBase import CartesianBase, LatLonEllipsoidalBase
from utils import EPS, degrees90, degrees180, degrees360, \
                  fpolynomial, radians, scalar

from math import atan2, cos, hypot, sin, tan

# all public contants, classes and functions
__all__ = ('Cartesian', 'LatLon', 'VincentyError')  # classes
__version__ = '17.09.22'


class VincentyError(ValueError):
    '''Error thrown from Vincenty's direct and inverse methods
       for coincident points and lack of convergence.
    '''
    pass


class LatLon(LatLonEllipsoidalBase):
    '''Using the formulae devised by Thaddeus Vincenty (1975) with an
       ellipsoidal model of the earth to compute the geodesic distance
       and bearings between two given points or the destination point
       given an start point and initial bearing.

       Set the earth model to be used with the keyword argument
       datum.  The default is Datums.WGS84, which is the most globally
       accurate.  For other models, see the Datums in module datum.

       Note: This implementation of the Vincenty methods may not
       converge for some valid points, raising a VincentyError.  In
       that case, a result may be obtained by increasing the epsilon
       and/or the iteration limit, see properties L{LatLon.epsilon}
       and L{LatLon.iterations}.
    '''
    _epsilon    = 1.0e-12  # about 0.006 mm
    _iterations = 50

    def copy(self):
        '''Copy this point.

           @return: Copy of this point (L{LatLon}).
        '''
        p = LatLonEllipsoidalBase.copy(self)
        assert hasattr(p, 'epsilon')
        p.epsilon = self.epsilon
        assert hasattr(p, 'iterations')
        p.iterations = self.iterations
        return p

    def destination(self, distance, bearing, height=None):
        '''Compute the destination point after having travelled
           for the given distance from this point along a geodesic
           given by an initial bearing, using Vincenty's direct
           method.  See method L{destination2} for more details.

           @param distance: Distance in meters (scalar).
           @param bearing: Initial bearing in compass degrees (scalar).
           @keyword height: Optional height, overriding the default
                            height (meter).

           @return: The destination point (L{LatLon}).

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit.

           @example:

           >>> p = LatLon(-37.95103, 144.42487)
           >>> d = p.destination(54972.271, 306.86816)  # 37.6528°S, 143.9265°E
        '''
        return self._direct(distance, bearing, True, height=height)[0]

    def destination2(self, distance, bearing, height=None):
        '''Compute the destination point and the final bearing (reverse
           azimuth) after having travelled for the given distance from
           this point along a geodesic given by an initial bearing,
           using Vincenty's direct method.

           The distance must be in the same units as this point's datum
           axes, conventially meter.  The distance is measured on the
           surface of the ellipsoid, ignoring this point's height.

           The initial and final bearing (aka forward and reverse azimuth)
           are in compass degrees.

           The destination point's height and datum are set to this
           point's height and datum.

           @param distance: Distance in meters (scalar).
           @param bearing: Initial bearing in compass degrees (scalar).
           @keyword height: Optional height, overriding the default
                            height (meter).

           @return: 2-Tuple (destination, final bearing) in (L{LatLon}, degrees360).

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit.

           @example:

           >>> p = LatLon(-37.95103, 144.42487)
           >>> b = 306.86816
           >>> d, f = p.destination2(54972.271, b)  # 37.652818°S, 143.926498°E, 307.1736
        '''
        return self._direct(distance, bearing, True, height=height)

    def distanceTo(self, other):
        '''Compute the distance between this and an other point
           along a geodesic, using Vincenty's inverse method.
           See method L{distanceTo3} for more details.

           @param other: The other point (L{LatLon}).

           @return: Distance in meters (scalar).

           @raise TypeError: The other point is not L{LatLon}.

           @raise ValueError: If this and the other point's L{Datum}
                              ellipsoids are not compatible.

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit or this and the other point coincide.

           @example:

           >>> p = LatLon(50.06632, -5.71475)
           >>> q = LatLon(58.64402, -3.07009)
           >>> d = p.distanceTo(q)  # 969,954.166 m
        '''
        return self._inverse(other, False)

    def distanceTo3(self, other):
        '''Compute the distance and the initial and final bearing along
           a geodesic between this and an other point, using Vincenty's
           inverse method.

           The distance is in the same units as this point's datum axes,
           conventially meter.  The distance is measured on the surface
           of the ellipsoid, ignoring this point's height.

           The initial and final bearing (aka forward and reverse azimuth)
           are in compass degrees from North.

           @param other: Destination point (L{LatLon}).

           @return: 3-Tuple (distance, initial bearing, final bearing)
           in (meter, degrees360, degree360).

           @raise TypeError: The other point is not L{LatLon}.

           @raise ValueError: If this and the other point's L{Datum}
                              ellipsoids are not compatible.

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit or this and the other point coincide.
        '''
        return self._inverse(other, True)

    @property
    def epsilon(self):
        '''Get the convergence epsilon (scalar).
        '''
        return self._epsilon

    @epsilon.setter  # PYCHOK setter!
    def epsilon(self, eps):
        '''Set the convergence epsilon.

           @param eps: New epsilon (scalar).

           @raise TypeError: Epsilon not scalar.

           @raise ValueError: Epsilon out of bounds.
        '''
        self._epsilon = scalar(eps, name='epsilon')

    def finalBearingOn(self, distance, bearing):
        '''Compute the final bearing (reverse azimuth) after having
           travelled for the given distance along a geodesic given
           by an initial bearing from this point, using Vincenty's
           direct method.  See method L{destination2} for more details.

           @param distance: Distance in meter (scalar).
           @param bearing: Initial bearing (compass degrees).

           @return: Final bearing from North (degrees360).

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit.

           @example:

           >>> p = LatLon(-37.95103, 144.42487)
           >>> b = 306.86816
           >>> f = p.finalBearingOn(54972.271, b)  # 307.1736
        '''
        return self._direct(distance, bearing, False)

    def finalBearingTo(self, other):
        '''Compute the final bearing (reverse azimuth) after having
           travelled along a geodesic from this point to an other
           point, using Vincenty's inverse method.  See method
           L{distanceTo3} for more details.

           @param other: The other point (L{LatLon}).

           @return: Final bearing in compass degrees (degrees360).

           @raise TypeError: The other point is not L{LatLon}.

           @raise ValueError: If this and the other point's L{Datum}
                              ellipsoids are not compatible.

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit or this and the other point coincide.

           @example:

           >>> p = new LatLon(50.06632, -5.71475)
           >>> q = new LatLon(58.64402, -3.07009)
           >>> f = p.finalBearingTo(q)  # 11.2972°

           >>> p = LatLon(52.205, 0.119)
           >>> q = LatLon(48.857, 2.351)
           >>> f = p.finalBearingTo(q)  # 157.9
        '''
        return self._inverse(other, True)[2]

    def initialBearingTo(self, other):
        '''Compute the initial bearing (forward azimuth) to travel
           along a geodesic from this point to an other point,
           using Vincenty's inverse method.  See method
           L{distanceTo3} for more details.

           @param other: The other point (L{LatLon}).

           @return: Initial bearing in compass degrees (degrees360).

           @raise TypeError: The other point is not L{LatLon}.

           @raise ValueError: If this and the other point's L{Datum}
                              ellipsoids are not compatible.

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit or this and the other point coincide.

           @example:

           >>> p = LatLon(50.06632, -5.71475)
           >>> q = LatLon(58.64402, -3.07009)
           >>> b = p.initialBearingTo(q)  # 9.141877°

           >>> p = LatLon(52.205, 0.119)
           >>> q = LatLon(48.857, 2.351)
           >>> b = p.initialBearingTo(q)  # 156.11064°

           @JSname: I{bearingTo}.
        '''
        return self._inverse(other, True)[1]

    bearingTo = initialBearingTo  # for backward compatibility

    @property
    def iterations(self):
        '''Get the iteration limit (int).
        '''
        return self._iterations

    @iterations.setter  # PYCHOK setter!
    def iterations(self, limit):
        '''Set the iteration limit.

           @param limit: New iteration limit (scalar).

           @raise TypeError: Limit not scalar.

           @raise ValueError: Limit out of bounds.
        '''
        self._iterations = scalar(limit, 4, 200, name='limit')

    def toCartesian(self):
        '''Convert this (geodetic) point to (geocentric) x/y/z
           Cartesian coordinates.

           @return: Ellipsoidal (geocentric) Cartesian point (L{Cartesian}).
        '''
        x, y, z = self.to3xyz()  # ellipsoidalBase.LatLonEllipsoidalBase
        return Cartesian(x, y, z)  # this ellipsoidalVincenty.Cartesian

    def _direct(self, distance, bearing, llr, height=None):
        '''(INTERNAL) Direct Vincenty method.

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit.
        '''
        E = self.ellipsoid()

        c1, s1, t1 = _r3(self.lat, E.f)

        i = radians(bearing)  # initial bearing (forward azimuth)
        ci, si = cos(i), sin(i)
        s12 = atan2(t1, ci) * 2

        sa = c1 * si
        c2a = 1 - (sa * sa)
        if c2a < EPS:
            c2a = 0
            A, B = 1, 0
        else:  # e22 == (a / b)**2 - 1
            A, B = _p2(c2a * E.e22)

        s = d = distance / (E.b * A)
        for _ in range(self._iterations):
            cs, ss, c2sm = cos(s), sin(s), cos(s12 + s)
            s_, s = s, d + _ds(B, cs, ss, c2sm)
            if abs(s - s_) < self._epsilon:
                break
        else:
            raise VincentyError('no convergence %r' % (self,))

        t = s1 * ss - c1 * cs * ci
        # final bearing (reverse azimuth +/- 180)
        r = degrees360(atan2(sa, -t))
        if llr:
            # destination latitude in [-270, 90)
            a = degrees90(atan2(s1 * cs + c1 * ss * ci,
                                (1 - E.f) * hypot(sa, t)))
            # destination longitude in [-180, 180)
            b = degrees180(atan2(ss * si, c1 * cs - s1 * ss * ci) -
                          _dl(E.f, c2a, sa, s, cs, ss, c2sm) +
                           radians(self.lon))
            h = self.height if height is None else height
            r = self.classof(a, b, height=h, datum=self.datum), r
        return r

    def _inverse(self, other, azis):
        '''(INTERNAL) Inverse Vincenty method.

           @raise TypeError: The other point is not L{LatLon}.

           @raise ValueError: If this and the other point's L{Datum}
                              ellipsoids are not compatible.

           @raise VincentyError: Vincenty fails to converge for the current
                                 L{LatLon.epsilon} and L{LatLon.iterations}
                                 limit or this and the other point coincide.
        '''
        E = self.ellipsoids(other)

        c1, s1, _ = _r3(self.lat, E.f)
        c2, s2, _ = _r3(other.lat, E.f)

        c1c2, s1s2 = c1 * c2, s1 * s2
        c1s2, s1c2 = c1 * s2, s1 * c2

        ll = dl = radians(other.lon - self.lon)
        for _ in range(self._iterations):
            cll, sll, ll_ = cos(ll), sin(ll), ll

            ss = hypot(c2 * sll, c1s2 - s1c2 * cll)
            if ss < EPS:
                raise VincentyError('%r coincides with %r' % (self, other))
            cs = s1s2 + c1c2 * cll
            s = atan2(ss, cs)

            sa = c1c2 * sll / ss
            c2a = 1 - sa**2
            if abs(c2a) < EPS:
                c2a = 0  # equatorial line
                ll = dl + E.f * sa * s
            else:
                c2sm = cs - 2 * s1s2 / c2a
                ll = dl + _dl(E.f, c2a, sa, s, cs, ss, c2sm)

            if abs(ll - ll_) < self._epsilon:
                break
        else:
            raise VincentyError('no convergence %r to %r' % (self, other))

        if c2a:  # e22 == (a / b)**2 - 1
            A, B = _p2(c2a * E.e22)
            s = A * (s - _ds(B, cs, ss, c2sm))

        b = E.b
#       if self.height or other.height:
#           b += self._havg(other)
        d = b * s

        if azis:  # forward and reverse azimuth
            cll, sll = cos(ll), sin(ll)
            f = degrees360(atan2(c2 * sll,  c1s2 - s1c2 * cll))
            r = degrees360(atan2(c1 * sll, -s1c2 + c1s2 * cll))
            d = d, f, r
        return d


def _p2(u2):  # e'2 WGS84 = 0.00673949674227643
    '''(INTERNAL) Compute A, B polynomials.
    '''
    A = fpolynomial(u2, 16384, 4096, -768, 320, -175) / 16384.0
    B = fpolynomial(u2,     0,  256, -128,  74,  -47) / 1024.0
    return A, B


def _r3(a, f):
    '''(INTERNAL) Reduced cos, sin, tan.
    '''
    t = (1 - f) * tan(radians(a))
    c = 1 / hypot(1, t)
    s = t * c
    return c, s, t


def _dl(f, c2a, sa, s, cs, ss, c2sm):
    '''(INTERNAL) Dl.
    '''
    C = f / 16.0 * c2a * (4 + f * (4 - 3 * c2a))
    return (1 - C) * f * sa * (s + C * ss * (c2sm +
                     C * cs * (2 * c2sm**2 - 1)))


def _ds(B, cs, ss, c2sm):
    '''(INTERNAL) Ds.
    '''
    c2sm2 = 2 * c2sm**2 - 1
    ss2 = (4 * ss**2 - 3) * (2 * c2sm2 - 1)
    return B * ss * (c2sm + B / 4.0 * (c2sm2 * cs -
                            B / 6.0 *  c2sm  * ss2))


class Cartesian(CartesianBase):
    '''Extended to convert (geocentric) L{Cartesian} points to
       Vincenty-based (ellipsoidal) geodetic L{LatLon}.
    '''
    def toLatLon(self, datum=Datums.WGS84, LatLon=LatLon):  # PYCHOK XXX
        '''Convert this (geocentric) Cartesian (x/y/z) point to
           an (ellipsoidal) geodetic point on the specified datum.

           @keyword datum: Optional datum to use (L{Datum}).
           @keyword LatLon: Optional LatLon class for the point (L{LatLon}).

           @return: The ellipsoidal geodetic point (L{LatLon}).
        '''
        a, b, h = self.to3llh(datum)
        return LatLon(a, b, height=h, datum=datum)


# **) MIT License
#
# Copyright (C) 2016-2017 -- mrJean1 at Gmail dot com
#
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