import numpy as np
from scipy import sparse as sp
from matutils import mkvc, ndgrid, sub2ind
from sputils import sdiag

def exampleLomGird(nC, exType):
    assert type(nC) == list, "nC must be a list containing the number of nodes"
    assert len(nC) == 2 or len(nC) == 3, "nC must either two or three dimensions"
    exType = exType.lower()

    possibleTypes = ['rect', 'rotate']
    assert exType in possibleTypes, "Not a possible example type."

    if exType == 'rect':
        return ndgrid([np.cumsum(np.r_[0, np.ones(nx)/nx]) for nx in nC], vector=False)
    elif exType == 'rotate':
        if len(nC) == 2:
            X, Y = ndgrid([np.cumsum(np.r_[0, np.ones(nx)/nx]) for nx in nC], vector=False)
            amt = 0.5-np.sqrt((X - 0.5)**2 + (Y - 0.5)**2)
            amt[amt < 0] = 0
            return X + (-(Y - 0.5))*amt, Y + (+(X - 0.5))*amt
        elif len(nC) == 3:
            X, Y, Z = ndgrid([np.cumsum(np.r_[0, np.ones(nx)/nx]) for nx in nC], vector=False)
            amt = 0.5-np.sqrt((X - 0.5)**2 + (Y - 0.5)**2 + (Z - 0.5)**2)
            amt[amt < 0] = 0
            return X + (-(Y - 0.5))*amt, Y + (-(Z - 0.5))*amt, Z + (-(X - 0.5))*amt


def meshTensors(*args):
    """
        **meshTensors** takes any number of tuples that have the form::

            h1 = ( (numPad, sizeStart [, increaseFactor]), (numCore, sizeCode), (numPad, sizeStart [, increaseFactor]) )

        .. plot::

            from SimPEG import mesh, utils
            M = mesh.TensorMesh(utils.meshTensors(((10,10),(40,10),(10,10)), ((10,10),(20,10),(0,0))))
            M.plotGrid()

    """
    def padding(num, start, factor=1.3, reverse=False):
        pad = ((np.ones(num)*factor)**np.arange(num))*start
        if reverse: pad = pad[::-1]
        return pad
    tensors = tuple()
    for i, arg in enumerate(args):
        tensors += (np.r_[padding(*arg[0],reverse=True),np.ones(arg[1][0])*arg[1][1],padding(*arg[2])],)

    return list(tensors) if len(tensors) > 1 else tensors[0]

if __name__ == '__main__':
    from SimPEG import mesh
    import matplotlib.pyplot as plt
    M = mesh.TensorMesh(meshTensors(((10,10),(40,10),(10,10)), ((10,10),(20,10),(0,0))))
    M.plotGrid()
    plt.gca().axis('tight')
    plt.show()