# Copyright (C) 2020 Jørgen S. Dokken
#
# This file is part of DOLFINX_MPC
#
# SPDX-License-Identifier:    MIT
from __future__ import annotations

import resource
from argparse import ArgumentDefaultsHelpFormatter, ArgumentParser
from pathlib import Path

from mpi4py import MPI
from petsc4py import PETSc

import basix.ufl
import h5py
import numpy as np
from dolfinx import default_real_type, default_scalar_type
from dolfinx.common import Timer, list_timings
from dolfinx.fem import (
    Constant,
    Function,
    dirichletbc,
    form,
    functionspace,
    locate_dofs_topological,
)
from dolfinx.fem.petsc import set_bc
from dolfinx.io import XDMFFile
from dolfinx.mesh import CellType, create_unit_cube, locate_entities_boundary, meshtags
from ufl import (
    Identity,
    SpatialCoordinate,
    TestFunction,
    TrialFunction,
    as_vector,
    ds,
    dx,
    grad,
    inner,
    sym,
    tr,
)

from dolfinx_mpc import MultiPointConstraint, apply_lifting, assemble_matrix, assemble_vector
from dolfinx_mpc.utils import log_info, rigid_motions_nullspace


def bench_elasticity_edge(
    tetra: bool = True,
    r_lvl: int = 0,
    out_hdf5=None,
    xdmf: bool = False,
    boomeramg: bool = False,
    kspview: bool = False,
    degree: int = 1,
    info: bool = False,
):
    N = 3
    for i in range(r_lvl):
        N *= 2
    ct = CellType.tetrahedron if tetra else CellType.hexahedron
    mesh = create_unit_cube(MPI.COMM_WORLD, N, N, N, ct)

    el = basix.ufl.element(
        "Lagrange", mesh.topology.cell_name(), int(degree), shape=(mesh.geometry.dim,), dtype=default_real_type
    )
    V = functionspace(mesh, el)

    # Generate Dirichlet BC (Fixed)
    u_bc = Function(V)
    u_bc.x.array[:] = 0

    def boundaries(x):
        return np.isclose(x[0], 0, 500 * np.finfo(x.dtype).resolution)

    fdim = mesh.topology.dim - 1
    facets = locate_entities_boundary(mesh, fdim, boundaries)
    topological_dofs = locate_dofs_topological(V, fdim, facets)
    bc = dirichletbc(u_bc, topological_dofs)
    bcs = [bc]

    def PeriodicBoundary(x):
        return np.logical_and(np.isclose(x[0], 1), np.isclose(x[2], 0))

    def periodic_relation(x):
        out_x = np.zeros(x.shape)
        out_x[0] = x[0]
        out_x[1] = x[1]
        out_x[2] = x[2] + 1
        return out_x

    with Timer("~Elasticity: Initialize MPC"):
        edim = mesh.topology.dim - 2
        edges = locate_entities_boundary(mesh, edim, PeriodicBoundary)
        arg_sort = np.argsort(edges)
        periodic_mt = meshtags(mesh, edim, edges[arg_sort], np.full(len(edges), 2, dtype=np.int32))

        mpc = MultiPointConstraint(V)
        mpc.create_periodic_constraint_topological(
            V, periodic_mt, 2, periodic_relation, bcs, scale=default_scalar_type(0.5)
        )
        mpc.finalize()

    # Create traction meshtag

    def traction_boundary(x):
        return np.isclose(x[0], 1)

    t_facets = locate_entities_boundary(mesh, fdim, traction_boundary)
    facet_values = np.ones(len(t_facets), dtype=np.int32)
    arg_sort = np.argsort(t_facets)
    mt = meshtags(mesh, fdim, t_facets[arg_sort], facet_values)

    # Elasticity parameters
    E = 1.0e4
    nu = 0.1
    mu = Constant(mesh, default_scalar_type(E / (2.0 * (1.0 + nu))))
    lmbda = Constant(mesh, default_scalar_type(E * nu / ((1.0 + nu) * (1.0 - 2.0 * nu))))
    g = Constant(mesh, default_scalar_type((0, 0, -1e2)))
    x = SpatialCoordinate(mesh)
    f = Constant(mesh, default_scalar_type(1e3)) * as_vector((0, -((x[2] - 0.5) ** 2), (x[1] - 0.5) ** 2))

    # Stress computation
    def epsilon(v):
        return sym(grad(v))

    def sigma(v):
        return 2.0 * mu * epsilon(v) + lmbda * tr(epsilon(v)) * Identity(len(v))

    # Define variational problem
    u = TrialFunction(V)
    v = TestFunction(V)
    a = inner(sigma(u), grad(v)) * dx
    rhs = inner(g, v) * ds(domain=mesh, subdomain_data=mt, subdomain_id=1) + inner(f, v) * dx

    # Setup MPC system
    if info:
        log_info(f"Run {r_lvl}: Assembling matrix and vector")
    bilinear_form = form(a)
    linear_form = form(rhs)
    with Timer("~Elasticity: Assemble LHS and RHS"):
        A = assemble_matrix(bilinear_form, mpc, bcs=bcs)
        b = assemble_vector(linear_form, mpc)

    # Create nullspace for elasticity problem and assign to matrix
    null_space = rigid_motions_nullspace(mpc.function_space)
    A.setNearNullSpace(null_space)

    # Apply boundary conditions
    apply_lifting(b, [bilinear_form], [bcs], mpc)
    b.ghostUpdate(addv=PETSc.InsertMode.ADD_VALUES, mode=PETSc.ScatterMode.REVERSE)  # type: ignore
    set_bc(b, bcs)

    opts = PETSc.Options()  # type: ignore
    if boomeramg:
        opts["ksp_type"] = "cg"
        opts["ksp_rtol"] = 1.0e-5
        opts["pc_type"] = "hypre"
        opts["pc_hypre_type"] = "boomeramg"
        opts["pc_hypre_boomeramg_max_iter"] = 1
        opts["pc_hypre_boomeramg_cycle_type"] = "v"
        # opts["pc_hypre_boomeramg_print_statistics"] = 1
    else:
        opts["ksp_rtol"] = 1.0e-8
        opts["pc_type"] = "gamg"
        opts["pc_gamg_type"] = "agg"
        opts["pc_gamg_coarse_eq_limit"] = 1000
        opts["pc_gamg_sym_graph"] = True
        opts["mg_levels_ksp_type"] = "chebyshev"
        opts["mg_levels_pc_type"] = "jacobi"
        opts["mg_levels_esteig_ksp_type"] = "cg"
        opts["matptap_via"] = "scalable"
        opts["pc_gamg_square_graph"] = 2
        opts["pc_gamg_threshold"] = 0.02
    # opts["help"] = None # List all available options
    # opts["ksp_view"] = None # List progress of solver

    # Setup PETSc solver
    solver = PETSc.KSP().create(mesh.comm)  # type: ignore
    solver.setFromOptions()  # type: ignore

    if info:
        log_info(f"Run {r_lvl}: Solving")

    with Timer("~Elasticity: Solve problem") as timer:
        solver.setOperators(A)
        uh = Function(mpc.function_space)
        uh.x.array[:] = 0
        solver.solve(b, uh.x.petsc_vec)
        uh.x.scatter_forward()
        mpc.backsubstitution(uh)
        solver_time = timer.elapsed().total_seconds()
    if kspview:
        solver.view()

    mem = sum(MPI.COMM_WORLD.allgather(resource.getrusage(resource.RUSAGE_SELF).ru_maxrss))
    it = solver.getIterationNumber()

    num_dofs = V.dofmap.index_map.size_global * V.dofmap.index_map_bs
    if out_hdf5 is not None:
        d_set = out_hdf5.get("its")
        d_set[r_lvl] = it
        d_set = out_hdf5.get("num_dofs")
        d_set[r_lvl] = num_dofs
        d_set = out_hdf5.get("num_slaves")
        d_set[r_lvl, MPI.COMM_WORLD.rank] = mpc.num_local_slaves
        d_set = out_hdf5.get("solve_time")
        d_set[r_lvl, MPI.COMM_WORLD.rank] = solver_time
    if info:
        log_info(f"Lvl: {r_lvl}, Its: {it}, max Mem: {mem}, dim(V): {num_dofs}")

    if xdmf:
        # Write solution to file
        u_h = Function(mpc.function_space)
        u_h.x.petsc_vec.setArray(uh.array)
        u_h.name = "u_mpc"
        results = Path("results").absolute()
        results.mkdir(exist_ok=True)
        fname = results / f"bench_elasticity_edge_{r_lvl}.xdmf"
        with XDMFFile(mesh.comm, fname, "w") as outfile:
            outfile.write_mesh(mesh)
            outfile.write_function(u_h)


if __name__ == "__main__":
    parser = ArgumentParser(formatter_class=ArgumentDefaultsHelpFormatter)
    parser.add_argument("--nref", default=1, type=np.int8, dest="n_ref", help="Number of spatial refinements")
    parser.add_argument("--degree", default=1, type=np.int8, dest="degree", help="CG Function space degree")
    parser.add_argument("--xdmf", action="store_true", dest="xdmf", help="XDMF-output of function (Default false)")
    parser.add_argument("--timings", action="store_true", dest="timings", help="List timings (Default false)")
    parser.add_argument(
        "--info",
        action="store_true",
        dest="info",
        help="Set loglevel to info (Default false)",
        default=False,
    )
    parser.add_argument("--kspview", action="store_true", dest="kspview", help="View PETSc progress")
    ct_parser = parser.add_mutually_exclusive_group(required=False)
    ct_parser.add_argument("--tet", dest="tetra", action="store_true", help="Tetrahedron elements")
    ct_parser.add_argument("--hex", dest="tetra", action="store_false", help="Hexahedron elements")
    solver_parser = parser.add_mutually_exclusive_group(required=False)
    solver_parser.add_argument(
        "--boomeramg",
        dest="boomeramg",
        default=True,
        action="store_true",
        help="Use BoomerAMG preconditioner (Default)",
    )
    solver_parser.add_argument("--gamg", dest="boomeramg", action="store_false", help="Use PETSc GAMG preconditioner")
    args = parser.parse_args()
    N = args.n_ref + 1
    out_file = Path("output/ench_edge_output.hdf5").absolute()
    out_file.parent.mkdir(exist_ok=True)
    h5f = h5py.File(out_file, "w", driver="mpio", comm=MPI.COMM_WORLD)
    h5f.create_dataset("its", (N,), dtype=np.int32)
    h5f.create_dataset("num_dofs", (N,), dtype=np.int32)
    h5f.create_dataset("num_slaves", (N, MPI.COMM_WORLD.size), dtype=np.int32)
    sd = h5f.create_dataset("solve_time", (N, MPI.COMM_WORLD.size), dtype=np.float64)
    solver = "BoomerAMG" if args.boomeramg else "GAMG"
    ct = "Tet" if args.tetra else "Hex"
    sd.attrs["solver"] = np.bytes_(solver)
    sd.attrs["degree"] = np.bytes_(str(int(args.degree)))
    sd.attrs["ct"] = np.bytes_(ct)

    for i in range(N):
        log_info(f"Run {i} in progress")
        bench_elasticity_edge(
            tetra=args.tetra,
            r_lvl=i,
            out_hdf5=h5f,
            xdmf=args.xdmf,
            boomeramg=args.boomeramg,
            kspview=args.kspview,
            degree=args.degree,
            info=args.info,
        )

        if args.timings and i == N - 1:
            list_timings(MPI.COMM_WORLD)
    h5f.close()
