#!/usr/bin/env python
"""
Convert a mesh file from one SfePy-supported format to another.

Examples::

  $ ./script/convert_mesh.py meshes/3d/cylinder.mesh new.vtk
  $ ./script/convert_mesh.py meshes/3d/cylinder.mesh new.vtk -s2.5
  $ ./script/convert_mesh.py meshes/3d/cylinder.mesh new.vtk -s0.5,2,1
  $ ./script/convert_mesh.py meshes/3d/cylinder.mesh new.vtk -s0.5,2,1 -c 0
  $ ./script/convert_mesh.py meshes/3d/cylinder.mesh new.mesh --remesh='q2/0 a1e-8 O9/7 V'
  $ ./script/convert_mesh.py meshes/3d/cylinder.mesh new2.mesh --remesh='rq2/0 a1e-8 O9/7 V'
"""
from __future__ import absolute_import
import sys
import os.path as op
from six.moves import range
sys.path.append('.')

from argparse import ArgumentParser, RawDescriptionHelpFormatter
from sfepy.base.base import nm, output
from sfepy.base.ioutils import remove_files
from sfepy.discrete.fem import Mesh, FEDomain
from sfepy.discrete.fem.meshio import (output_mesh_formats, MeshIO,
                                       supported_cell_types)
from sfepy.discrete.fem.mesh import fix_double_nodes
from sfepy.mesh.mesh_tools import elems_q2t

helps = {
    'scale' : 'scale factor (float or comma-separated list for each axis)'
    ' [default: %(default)s]',
    'center' : 'center of the output mesh (0 for origin or'
    ' comma-separated list for each axis) applied after scaling'
    ' [default: %(default)s]',
    'refine' : 'uniform refinement level [default: %(default)s]',
    'format' : 'output mesh format (overrides filename_out extension)',
    'list' : 'list supported readable/writable output mesh formats',
    'merge' : 'remove duplicate vertices',
    'tri-tetra' : 'convert elements: quad->tri, hexa->tetra',
    '2d' : 'force a 2D mesh by removing the z coordinates - assumes a 3D mesh'
    ' in the xy plane',
    'save-per-mat': 'extract cells by material id and save them into'
    ' separate mesh files with a name based on filename_out and the id'
    ' numbers (preserves original mesh vertices)',

    'remesh' : """when given, remesh the given mesh using tetgen.
      The options can be the following, separated by spaces, in this order: 1.
      "r" causes remeshing of the mesh volume - if not present the mesh surface
      is extracted and used for the volume mesh generation. 2.
      "q[<float>/<float>]" (required) - the two numbers after "q" are a maximum
      radius-edge ratio bound and a minimum dihedral angle bound. 3. "a<float>"
      (optional) - the number imposes a maximum volume constraint on all
      tetrahedra. 4. O[<0-9>/<0-7>] - the two numbers correspond to a mesh
      optimization level and a choice of optimizing operations. 5. "V"
      (optional) - if present, mesh statistics are printed. Consult the tetgen
      documentation for details.""",
}

def _parse_val_or_vec(option, name, parser):
    if option is not None:
        try:
            try:
                option = float(option)
            except ValueError:
                option = [float(ii) for ii in option.split(',')]
            option = nm.array(option, dtype=nm.float64, ndmin=1)
        except:
            output('bad %s! (%s)' % (name, option))
            parser.print_help()
            sys.exit(1)

    return option

def main():
    parser = ArgumentParser(description=__doc__,
                            formatter_class=RawDescriptionHelpFormatter)
    parser.add_argument('-s', '--scale', metavar='scale',
                        action='store', dest='scale',
                        default=None, help=helps['scale'])
    parser.add_argument('-c', '--center', metavar='center',
                        action='store', dest='center',
                        default=None, help=helps['center'])
    parser.add_argument('-r', '--refine', metavar='level',
                        action='store', type=int, dest='refine',
                        default=0, help=helps['refine'])
    parser.add_argument('-f', '--format', metavar='format',
                        action='store', type=str, dest='format',
                        default=None, help=helps['format'])
    parser.add_argument('-l', '--list', action='store_true',
                        dest='list', help=helps['list'])
    parser.add_argument('-m', '--merge', action='store_true',
                        dest='merge', help=helps['merge'])
    parser.add_argument('-t', '--tri-tetra', action='store_true',
                        dest='tri_tetra', help=helps['tri-tetra'])
    parser.add_argument('-2', '--2d', action='store_true',
                        dest='force_2d', help=helps['2d'])
    parser.add_argument('--save-per-mat', action='store_true',
                        dest='save_per_mat', help=helps['save-per-mat'])
    parser.add_argument('--remesh', metavar='options',
                        action='store', dest='remesh',
                        default=None, help=helps['remesh'])
    parser.add_argument('filename_in')
    parser.add_argument('filename_out')
    options = parser.parse_args()

    if options.list:
        output('Supported readable mesh formats:')
        output('--------------------------------')
        output_mesh_formats('r')
        output('')
        output('Supported writable mesh formats:')
        output('--------------------------------')
        output_mesh_formats('w')
        sys.exit(0)

    scale = _parse_val_or_vec(options.scale, 'scale', parser)
    center = _parse_val_or_vec(options.center, 'center', parser)

    filename_in = options.filename_in
    filename_out = options.filename_out

    if options.remesh:
        import tempfile
        import shlex
        import subprocess

        dirname = tempfile.mkdtemp()

        is_surface = options.remesh.startswith('q')
        if is_surface:
            mesh = Mesh.from_file(filename_in)
            domain = FEDomain(mesh.name, mesh)
            region = domain.create_region('surf', 'vertices of surface',
                                          'facet')
            surf_mesh = Mesh.from_region(region, mesh,
                                         localize=True, is_surface=True)

            filename = op.join(dirname, 'surf.mesh')
            surf_mesh.write(filename, io='auto')

        else:
            import shutil

            shutil.copy(filename_in, dirname)
            filename = op.join(dirname, op.basename(filename_in))

        qopts = ''.join(options.remesh.split()) # Remove spaces.
        command = 'tetgen -BFENkACp%s %s' % (qopts, filename)
        args = shlex.split(command)
        subprocess.call(args)

        root, ext = op.splitext(filename)
        mesh = Mesh.from_file(root + '.1.vtk')

        remove_files(dirname)

    else:
        mesh = Mesh.from_file(filename_in)

    if options.force_2d:
        data = list(mesh._get_io_data())
        data[0] = data[0][:, :2]
        mesh = Mesh.from_data(mesh.name, *data)

    if scale is not None:
        if len(scale) == 1:
            tr = nm.eye(mesh.dim, dtype=nm.float64) * scale
        elif len(scale) == mesh.dim:
            tr = nm.diag(scale)
        else:
            raise ValueError('bad scale! (%s)' % scale)
        mesh.transform_coors(tr)

    if center is not None:
        cc = 0.5 * mesh.get_bounding_box().sum(0)
        shift = center - cc
        tr = nm.c_[nm.eye(mesh.dim, dtype=nm.float64), shift[:, None]]
        mesh.transform_coors(tr)

    if options.refine > 0:
        domain = FEDomain(mesh.name, mesh)
        output('initial mesh: %d nodes %d elements'
               % (domain.shape.n_nod, domain.shape.n_el))

        for ii in range(options.refine):
            output('refine %d...' % ii)
            domain = domain.refine()
            output('... %d nodes %d elements'
                   % (domain.shape.n_nod, domain.shape.n_el))

        mesh = domain.mesh

    if options.tri_tetra > 0:
        conns = None
        for k, new_desc in [('3_8', '3_4'), ('2_4', '2_3')]:
            if k in mesh.descs:
                conns = mesh.get_conn(k)
                break

        if conns is not None:
            nelo = conns.shape[0]
            output('initial mesh: %d elements' % nelo)

            new_conns = 
elems_q2t(conns)