# ***************************************************************************
# *                                                                         *
# *   Copyright (c) 2016 - Bernd Hahnebach <bernd@bimstatik.org>            *
# *                                                                         *
# *   This program is free software; you can redistribute it and/or modify  *
# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
# *   as published by the Free Software Foundation; either version 2 of     *
# *   the License, or (at your option) any later version.                   *
# *   for detail see the LICENCE text file.                                 *
# *                                                                         *
# *   This program is distributed in the hope that it will be useful,       *
# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
# *   GNU Library General Public License for more details.                  *
# *                                                                         *
# *   You should have received a copy of the GNU Library General Public     *
# *   License along with this program; if not, write to the Free Software   *
# *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
# *   USA                                                                   *
# *                                                                         *
# ***************************************************************************

__title__ = "Tools for the work with GMSH mesher"
__author__ = "Bernd Hahnebach"
__url__ = "http://www.freecadweb.org"

## \addtogroup FEM
#  @{

import FreeCAD
import Fem
import FemMeshTools
import Units
import subprocess
import tempfile
import math
from platform import system


class CfdGmshTools():
    def __init__(self, gmsh_mesh_obj, analysis=None):
        self.mesh_obj = gmsh_mesh_obj
        if analysis:
            self.analysis = analysis
            # group meshing turned on
        else:
            self.analysis = None
            # group meshing turned off

        # part to mesh
        self.part_obj = self.mesh_obj.Part

        # Default characteristic length to 5/100 of bounding box length
        self.clmax = Units.Quantity(self.mesh_obj.CharacteristicLengthMax).Value
        if self.clmax == 0.0:
            # self.clmax = 1e+22
            shape = self.part_obj.Shape
            clBoundBox = math.sqrt(shape.BoundBox.XLength**2 + shape.BoundBox.YLength**2 + shape.BoundBox.ZLength**2)
            self.clmax = 0.05*clBoundBox

        # clmin, CharacteristicLengthMin: float
        self.clmin = Units.Quantity(self.mesh_obj.CharacteristicLengthMin).Value

        # order
        # known_element_orders = ['1st', '2nd']
        self.order = self.mesh_obj.ElementOrder
        if self.order == '1st':
            self.order = '1'
        elif self.order == '2nd':
            self.order = '2'
        else:
            print('Error in order')

        # dimension
        self.dimension = self.mesh_obj.ElementDimension

        # Algorithm2D
        # known_mesh_algorithm_2D = ['Automatic', 'MeshAdapt', 'Delaunay', 'Frontal', 'BAMG', 'DelQuad']
        algo2D = self.mesh_obj.Algorithm2D
        if algo2D == 'Automatic':
            self.algorithm2D = '2'
        elif algo2D == 'MeshAdapt':
            self.algorithm2D = '1'
        elif algo2D == 'Delaunay':
            self.algorithm2D = '5'
        elif algo2D == 'Frontal':
            self.algorithm2D = '6'
        elif algo2D == 'BAMG':
            self.algorithm2D = '7'
        elif algo2D == 'DelQuad':
            self.algorithm2D = '8'
        else:
            self.algorithm2D = '2'

        # Algorithm3D
        # known_mesh_algorithm_3D = ['Automatic', 'Delaunay', 'New Delaunay', 'Frontal', 'Frontal Delaunay', 'Frontal Hex', 'MMG3D', 'R-tree']
        algo3D = self.mesh_obj.Algorithm2D
        if algo3D == 'Automatic':
            self.algorithm3D = '1'
        elif algo3D == 'Delaunay':
            self.algorithm3D = '1'
        elif algo3D == 'New Delaunay':
            self.algorithm3D = '2'
        elif algo3D == 'Frontal':
            self.algorithm3D = '4'
        elif algo3D == 'Frontal Delaunay':
            self.algorithm3D = '5'
        elif algo3D == 'Frontal Hex':
            self.algorithm3D = '6'
        elif algo3D == 'MMG3D':
            self.algorithm3D = '7'
        elif algo3D == 'R-tree':
            self.algorithm3D = '9'
        else:
            self.algorithm3D = '1'

    def create_mesh(self):
        print("\nWe gone start GMSH FEM mesh run!")
        print('  Part to mesh: Name --> ' + self.part_obj.Name + ',  Label --> ' + self.part_obj.Label + ', ShapeType --> ' + self.part_obj.Shape.ShapeType)
        print('  CharacteristicLengthMax: ' + str(self.clmax))
        print('  CharacteristicLengthMin: ' + str(self.clmin))
        print('  ElementOrder: ' + self.order)
        self.get_dimension()
        self.get_tmp_file_paths()
        self.get_gmsh_command()
        self.get_group_data()
        self.write_part_file()
        self.write_geo()
        error = self.run_gmsh_with_geo()
        self.read_and_set_new_mesh()
        return error

    def get_dimension(self):
        # Dimension
        # known_element_dimensions = ['From Shape', '1D', '2D', '3D']
        # if not given, GMSH uses the hightest available.
        # A use case for not "From Shape" would be a surface (2D) mesh of a solid
        if self.dimension == 'From Shape':
            shty = self.part_obj.Shape.ShapeType
            if shty == 'Solid' or shty == 'CompSolid':
                # print('Found: ' + shty)
                self.dimension = '3'
            elif shty == 'Face' or shty == 'Shell':
                # print('Found: ' + shty)
                self.dimension = '2'
            elif shty == 'Edge' or shty == 'Wire':
                # print('Found: ' + shty)
                self.dimension = '1'
            elif shty == 'Vertex':
                # print('Found: ' + shty)
                FreeCAD.Console.PrintError("You can not mesh a Vertex.\n")
                self.dimension = '0'
            elif shty == 'Compound':
                print('  Found a ' + shty)
                err = "A Compound could contain anything. GMSH may not return the expected mesh. It is strongly recommended to extract the shape to mesh from the Compound and use this one."
                FreeCAD.Console.PrintError(err + "\n")
                self.dimension = '3'  # dimension 3 works for 2D and 1d shapes as well
            else:
                self.dimension = '0'
                FreeCAD.Console.PrintError('Could not retrive Dimension from shape type. Please choose dimension.')
        elif self.dimension == '3D':
            self.dimension = '3'
        elif self.dimension == '2D':
            self.dimension = '2'
        elif self.dimension == '1D':
            self.dimension = '1'
        else:
            print('Error in dimension')
        print('  ElementDimension: ' + self.dimension)

    def get_tmp_file_paths(self):
        if system() == "Linux":
            path_sep = "/"
        elif system() == "Windows":
            path_sep = "\\"
        else:
            path_sep = "/"
        tmpdir = tempfile.gettempdir()
        # geometry file
        self.temp_file_geometry = tmpdir + path_sep + self.part_obj.Name + '_Geometry.brep'
        print('  ' + self.temp_file_geometry)
        # mesh file
        self.mesh_name = self.part_obj.Name + '_Mesh_TmpGmsh'
        self.temp_file_mesh = tmpdir + path_sep + self.mesh_name + '.unv'
        print('  ' + self.temp_file_mesh)
        # GMSH input file
        self.temp_file_geo = tmpdir + path_sep + 'shape2mesh.geo'
        print('  ' + self.temp_file_geo)

    def get_gmsh_command(self):
        self.gmsh_bin = None
        gmsh_std_location = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem/Gmsh").GetBool("UseStandardGmshLocation")
        if gmsh_std_location:
            if system() == "Windows":
                gmsh_path = FreeCAD.getHomePath() + "bin/gmsh.exe"
                FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem/Gmsh").SetString("gmshBinaryPath", gmsh_path)
                self.gmsh_bin = gmsh_path
            elif system() == "Linux":
                p1 = subprocess.Popen(['which', 'gmsh'], stdout=subprocess.PIPE)
                if p1.wait() == 0:
                    gmsh_path = p1.stdout.read().split('\n')[0]
                elif p1.wait() == 1:
                    error_message = "GMSH binary gmsh not found in standard system binary path. Please install gmsh or set path to binary in FEM preferences tab GMSH.\n"
                    FreeCAD.Console.PrintError(error_message)
                    raise Exception(error_message)
                self.gmsh_bin = gmsh_path
            else:
                error_message = "No standard location implemented for your operating system. Set GMHS binary path in FEM preferences.\n"
                FreeCAD.Console.PrintError(error_message)
                raise Exception(error_message)
        else:
            if not self.gmsh_bin:
                self.gmsh_bin = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem/Gmsh").GetString("gmshBinaryPath", "")
            if not self.gmsh_bin:  # in prefs not set, we will try to use something reasonable
                if system() == "Linux":
                    self.gmsh_bin = "gmsh"
                elif system() == "Windows":
                    self.gmsh_bin = FreeCAD.getHomePath() + "bin/gmsh.exe"
                else:
                    self.gmsh_bin = "gmsh"
        print('  ' + self.gmsh_bin)

    def get_group_data(self):
        self.group_elements = {}
        # TODO solid, face, edge seam not work together, some print or make it work together
        # TODO handle groups for Edges and Vertexes

        # mesh groups and groups of analysis member
        if not self.mesh_obj.MeshGroupList:
            print ('  No mesh group objects.')
        else:
            print ('  Mesh group objects, we need to get the elements.')
            for mg in self.mesh_obj.MeshGroupList:
                new_group_elements = FemMeshTools.get_mesh_group_elements(mg, self.part_obj)
                for ge in new_group_elements:
                    if ge not in self.group_elements:
                        self.group_elements[ge] = new_group_elements[ge]
                    else:
                        FreeCAD.Console.PrintError("  A group with this name exists already.\n")
        if self.analysis:
            print('  Group meshing.')
            new_group_elements = FemMeshTools.get_analysis_group_elements(self.analysis, self.part_obj)
            for ge in new_group_elements:
                if ge not in self.group_elements:
                    self.group_elements[ge] = new_group_elements[ge]
                else:
                    FreeCAD.Console.PrintError("  A group with this name exists already.\n")
        else:
            print('  No anlysis members for group meshing.')
        print('  {}'.format(self.group_elements))

        # mesh regions
        self.ele_length_map = {}  # { 'ElementString' : element length }
        self.ele_node_map = {}  # { 'ElementString' : [element nodes] }
        if not self.mesh_obj.MeshRegionList:
            print ('  No mesh regions.')
        else:
            print ('  Mesh regions, we need to get the elements.')
            if self.part_obj.Shape.ShapeType == 'Compound':
                # see http://forum.freecadweb.org/viewtopic.php?f=18&t=18780&start=40#p149467 and http://forum.freecadweb.org/viewtopic.php?f=18&t=18780&p=149520#p149520
                err = "GMSH could return unexpected meshes for a boolean split tools Compound. It is strongly recommended to extract the shape to mesh from the Compound and use this one."
                FreeCAD.Console.PrintError(err + "\n")
            for mr_obj in self.mesh_obj.MeshRegionList:
                if mr_obj.RelativeLength:
                    if mr_obj.References:
                        for sub in mr_obj.References:
                            # print(sub[0])  # Part the elements belongs to
                            # check if the shape of the mesh region is an element of the Part to mesh, if not try to find the element in the shape to mesh
                            search_ele_in_shape_to_mesh = False
                            if not self.part_obj.Shape.isSame(sub[0].Shape):
                                # print("  One element of the meshregion " + mr_obj.Name + " is not an element of the Part to mesh.")
                                # print("  But we gone try to find it in the Shape to mesh :-)")
                                search_ele_in_shape_to_mesh = True
                            for elems in sub[1]:
                                # print(elems)  # elems --> element
                                if search_ele_in_shape_to_mesh:
                                    # we gone try to find the element it in the Shape to mesh and use the found element as elems
                                    ele_shape = FemMeshTools.get_element(sub[0], elems)  # the method getElement(element) does not return Solid elements
                                    found_element = FemMeshTools.find_element_in_shape(self.part_obj.Shape, ele_shape)
                                    if found_element:
                                        elems = found_element
                                    else:
                                        FreeCAD.Console.PrintError("One element of the meshregion " + mr_obj.Name + " could not be found in the Part to mesh. It will be ignored.\n")
                                # print(elems)  # element
                                if elems not in self.ele_length_map:
                                    # self.ele_length_map[elems] = Units.Quantity(mr_obj.CharacteristicLength).Value
                                    mr_rellen = mr_obj.RelativeLength
                                    if mr_rellen > 1.0:
                                        mr_rellen = 1.0
                                        FreeCAD.Console.PrintError("The meshregion: " + mr_obj.Name + " should not use a relative length greater than unity.\n")
                                    elif mr_rellen < 0.01:
                                        mr_rellen = 0.01  # Relative length should not be less than 1/100 of base length
                                        FreeCAD.Console.PrintError("The meshregion: " + mr_obj.Name + " should not use a relative length smaller than 0.01.\n")

                                    self.ele_length_map[elems] = mr_rellen*self.clmax
                                else:
                                    FreeCAD.Console.PrintError("The element " + elems + " of the meshregion " + mr_obj.Name + " has been added to another mesh region.\n")
                    else:
                        FreeCAD.Console.PrintError("The meshregion: " + mr_obj.Name + " is not used to create the mesh because the reference list is empty.\n")
                else:
                    FreeCAD.Console.PrintError("The meshregion: " + mr_obj.Name + " is not used to create the mesh because the CharacteristicLength is 0.0 mm.\n")
            for eleml in self.ele_length_map:
                ele_shape = FemMeshTools.get_element(self.part_obj, eleml)  # the method getElement(element) does not return Solid elements
                ele_vertexes = FemMeshTools.get_vertexes_by_element(self.part_obj.Shape, ele_shape)
                self.ele_node_map[eleml] = ele_vertexes
        print('  {}'.format(self.ele_length_map))
        print('  {}'.format(self.ele_node_map))

    def write_part_file(self):
        self.part_obj.Shape.exportBrep(self.temp_file_geometry)

    def write_geo(self):
        geo = open(self.temp_file_geo, "w")
        geo.write("// geo file for meshing with GMSH meshing software created by FreeCAD\n")
        geo.write("\n")
        geo.write("// open brep geometry\n")
        geo.write('Merge "' + self.temp_file_geometry + '";\n')
        geo.write("\n")
        if self.group_elements:
            # print('  We gone have found elements to make mesh groups for.')
            geo.write("// group data\n")
            # we use the element name of FreeCAD which starts with 1 (example: 'Face1'), same as GMSH
            for group in self.group_elements:
                gdata = self.group_elements[group]
                # print(gdata)
                # geo.write("// " + group + "\n")
                ele_nr = ''
                if gdata[0].startswith('Solid'):
                    physical_type = 'Volume'
                    for ele in gdata:
                        ele_nr += (ele.lstrip('Solid') + ', ')
                elif gdata[0].startswith('Face'):
                    physical_type = 'Surface'
                    for ele in gdata:
                        ele_nr += (ele.lstrip('Face') + ', ')
                elif gdata[0].startswith('Edge') or gdata[0].startswith('Vertex'):
                    geo.write("// " + group + " group data not written. Edges or Vertexes group data not supported.\n")
                    print('  Groups for Edges or Vertexes reference shapes not handeled yet.')
                if ele_nr:
                    ele_nr = ele_nr.rstrip(', ')
                    # print(ele_nr)
                    geo.write('Physical ' + physical_type + '("' + group + '") = {' + ele_nr + '};\n')
            geo.write("\n")
        geo.write("// Characteristic Length\n")
        if self.ele_length_map:
            # we use the index FreeCAD which starts with 0, we need to add 1 for the index in GMSH
            geo.write("// Characteristic Length according CharacteristicLengthMap\n")
            for e in self.ele_length_map:
                ele_nodes = (''.join((str(n + 1) + ', ') for n in self.ele_node_map[e])).rstrip(', ')
                geo.write("// " + e + "\n")
                geo.write("Characteristic Length { " + ele_nodes + " } = " + str(self.ele_length_map[e]) + ";\n")
            geo.write("\n")
        geo.write("// min, max Characteristic Length\n")
        geo.write("Mesh.CharacteristicLengthMax = " + str(self.clmax) + ";\n")
        geo.write("Mesh.CharacteristicLengthMin = " + str(self.clmin) + ";\n")
        geo.write("\n")
        if hasattr(self.mesh_obj, 'RecombineAll') and self.mesh_obj.RecombineAll is True:
            geo.write("// other mesh options\n")
            geo.write("Mesh.RecombineAll = 1;\n")
            geo.write("\n")
        geo.write("// optimize the mesh\n")
        # GMSH tetra optimizer
        if hasattr(self.mesh_obj, 'OptimizeStd') and self.mesh_obj.OptimizeStd is True:
            geo.write("Mesh.Optimize = 1;\n")
        else:
            geo.write("Mesh.Optimize = 0;\n")
        # Netgen optimizer in GMSH
        if hasattr(self.mesh_obj, 'OptimizeNetgen') and self.mesh_obj.OptimizeNetgen is True:
            geo.write("Mesh.OptimizeNetgen = 1;\n")
        else:
            geo.write("Mesh.OptimizeNetgen = 0;\n")
        # hight order mesh optimizing
        if hasattr(self.mesh_obj, 'OptimizeNetgen') and self.mesh_obj.OptimizeNetgen is True:
            geo.write("Mesh.HighOrderOptimize = 1;  //probably needs more lines off adjustment in geo file\n")
        else:
            geo.write("Mesh.HighOrderOptimize = 0;  //probably needs more lines off adjustment in geo file\n")
        geo.write("\n")
        geo.write("// mesh order\n")
        geo.write("Mesh.ElementOrder = " + self.order + ";\n")
        geo.write("\n")
        geo.write("// mesh algorithm\n")
        geo.write("// 2D mesh algorithm (1=MeshAdapt, 2=Automatic, 5=Delaunay, 6=Frontal, 7=BAMG, 8=DelQuad)\n")
        geo.write("Mesh.Algorithm = " + self.algorithm2D + ";\n")
        geo.write("// 3D mesh algorithm (1=Delaunay, 2=New Delaunay, 4=Frontal, 5=Frontal Delaunay, 6=Frontal Hex, 7=MMG3D, 9=R-tree)\n")
        geo.write("Mesh.Algorithm3D = " + self.algorithm3D + ";\n")
        geo.write("\n")
        geo.write("// meshing\n")
        geo.write("Mesh  " + self.dimension + ";\n")
        geo.write("\n")
        geo.write("// save\n")
        geo.write("Mesh.Format = 2;\n")  # unv
        if self.analysis and self.group_elements:
            geo.write("// For each group save not only the elements but the nodes too.;\n")
            geo.write("Mesh.SaveGroupsOfNodes = 1;\n")
            geo.write("// Needed for Group meshing too, because for one material there is no group defined;\n")  # belongs to Mesh.SaveAll but anly needed if there are groups
        geo.write("// Ignore Physical definitions and save all elements;\n")
        geo.write("Mesh.SaveAll = 1;\n")
        geo.write('Save "' + self.temp_file_mesh + '";\n')
        geo.write("\n\n")
        geo.write("//////////////////////////////////////////////////////////////////////\n")
        geo.write("// GMSH documentation:\n")
        geo.write("// http://gmsh.info/doc/texinfo/gmsh.html#Mesh\n")
        geo.write("//\n")
        geo.write("// We do not check if something went wrong, like negative jacobians etc. You can run GMSH manually yourself: \n")
        geo.write("//\n")
        geo.write("// to see full GMSH log, run in bash:\n")
        geo.write("// " + self.gmsh_bin + " - " + self.temp_file_geo + "\n")
        geo.write("//\n")
        geo.write("// to run GMSH and keep file in GMSH GUI (with log), run in bash:\n")
        geo.write("// " + self.gmsh_bin + " " + self.temp_file_geo + "\n")
        geo.close

    def run_gmsh_with_geo(self):
        self.error = False
        comandlist = [self.gmsh_bin, '-', self.temp_file_geo]
        # print(comandlist)
        try:
            p = subprocess.Popen(comandlist, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            output, error = p.communicate()
            # print(output)  # stdout is still cut at some point but the warnings are in stderr and thus printed :-)
            # print(error)
        except:
            error = 'Error executing: {}\n'.format(self.gmsh_command)
            FreeCAD.Console.PrintError(error)
            self.error = True
        return error

    def read_and_set_new_mesh(self):
        if not self.error:
            fem_mesh = Fem.read(self.temp_file_mesh)
            self.mesh_obj.FemMesh = fem_mesh
            print('  The Part should have a pretty new FEM mesh!')
        else:
            print('No mesh was created.')
        del self.temp_file_geometry
        del self.temp_file_mesh

##  @}
