import os
import json
import time
import argparse
from functools import partial

import tqdm
import numpy as np
import scipy
import pandas as pd

import torch
from torch.utils.data import DataLoader, Subset

import cupy as cp
import pyscf
import pyscf.df

from gto import GTOBasis, element_to_atomic_number, GTOProductBasisHelper, build_irreps_from_mol, pyscf_to_standard_perm_D
from dataset import SCFBenchDataset
from nequip_model import nequip_simple_builder


def move_data_to_device(data, device):
    def move(x):
        if isinstance(x, torch.Tensor):
            return x.to(device)
        elif isinstance(x, dict):
            return {k: move(v) for k, v in x.items()}
        else:
            return x
    return move(data)


def run_scf_and_count_steps(mol, xc, dm0=None, verbose=False, with_df=False, with_df_basis='def2-svp-jkfit'):
    t_start = time.time()

    mf = mol.RKS(xc=xc)
    if with_df:
        mf = mf.density_fit(auxbasis=with_df_basis)
    mf = mf.to_gpu()
    if verbose:
        mf.verbose = 4
    else:
        mf.verbose = 0

    mf.scf(dm0=dm0)
    steps = mf.cycles if mf.converged else -1
    e_tot = mf.e_tot

    return e_tot, steps, time.time() - t_start


def transfer_fock(mol, transfer_mol, fock):
    S_cross = pyscf.gto.mole.intor_cross('int1e_ovlp', mol, transfer_mol)
    S1 = mol.intor('int1e_ovlp')
    C = scipy.linalg.solve(S1, S_cross)
    transfer_fock = C.T.dot(fock).dot(C)
    return transfer_fock


def dm_from_fock(mol, overlap, fock):
    # from QHNet
    overlap = torch.tensor(overlap)
    fock = torch.tensor(fock)
    eigvals, eigvecs = torch.linalg.eigh(overlap)
    eps = 1e-8 * torch.ones_like(eigvals)
    eigvals = torch.where(eigvals > 1e-8, eigvals, eps)
    frac_overlap = eigvecs / torch.sqrt(eigvals).unsqueeze(-2)

    Fs = torch.mm(torch.mm(frac_overlap.transpose(-1, -2), fock), frac_overlap)
    orbital_energies, orbital_coefficients = torch.linalg.eigh(Fs)
    orbital_coefficients = torch.mm(frac_overlap, orbital_coefficients)
    num_orb = mol.nelectron // 2
    orbital_coefficients = orbital_coefficients.squeeze()
    dm0 = orbital_coefficients[:, :num_orb].matmul(orbital_coefficients[:, :num_orb].T) * 2
    dm0 = dm0.cpu().numpy()
    return dm0


def dm_from_auxdensity(mol, auxmol, xc, aux_vec, normalize_nelec, transfer_mol=None):
    import numpy
    import cupy
    from pyscf import lib
    import gpu4pyscf.scf.jk
    from gpu4pyscf.df.int3c2e_bdiv import Int3c2eOpt
    from gpu4pyscf.lib.cupy_helper import contract
    from gpu4pyscf.dft.numint import NumInt, add_sparse, _tau_dot, _scale_ao, _GDFTOpt
    from gpu4pyscf.dft import Grids
    from gpu4pyscf.lib.cupy_helper import transpose_sum

    def nr_rks(xctype, mol, xc_code, auxmol, aux_vec):
        # xctype = ni._xc_type(xc_code)
        if xctype == 'LDA':
            ao_deriv = 0
        else:
            ao_deriv = 1
        comp = (ao_deriv+1)*(ao_deriv+2)*(ao_deriv+3)//6

        grids = Grids(mol).build()
        ngrids = grids.weights.size

        rho = cupy.zeros((comp, ngrids))
        aux_ni = NumInt().build(auxmol, grids)
        naux = aux_ni.gdftopt._sorted_mol.nao
        _sorted_aux_vec = aux_ni.gdftopt.sort_orbitals(aux_vec, axis=[0])

        p0 = p1 = 0
        for aux_ao_on_grids, idx, weight, _ in aux_ni.block_loop(aux_ni.gdftopt._sorted_mol, grids, naux, ao_deriv):
            p0, p1 = p1, p1 + weight.size
            rho[:,p0:p1] = (contract('xig,i->xg', aux_ao_on_grids, _sorted_aux_vec[idx]))

        del aux_ao_on_grids, _sorted_aux_vec

        grids = Grids(mol).build()
        ni = NumInt().build(mol, grids)
        if xctype == 'MGGA':
            rho = cupy.vstack([rho, (rho[1:4]**2).sum(axis=0)/rho[0]/8])
        weights = cupy.asarray(grids.weights)
        nelec = rho[0].dot(weights)
        exc, vxc = ni.eval_xc_eff(xc_code, rho, deriv=1, xctype=xctype)[:2]
        vxc = cupy.asarray(vxc, order='C')
        exc = cupy.asarray(exc, order='C')
        excsum = float(cupy.dot(rho[0]*weights, exc[:,0]))
        wv = vxc
        wv *= weights
        if xctype == 'GGA':
            wv[0] *= .5
        if xctype == 'MGGA':
            wv[[0,4]] *= .5

        opt = ni.gdftopt
        _sorted_mol = opt._sorted_mol
        nao = _sorted_mol.nao
        buf = None
        vtmp_buf = cupy.empty(nao*nao)
        vmat = cupy.zeros((nao, nao))
        p0 = p1 = 0
        for ao_mask, idx, weight, _ in ni.block_loop(
                _sorted_mol, grids, nao, ao_deriv, max_memory=None):
            p0, p1 = p1, p1 + weight.size
            nao_sub = len(idx)
            vtmp = cupy.ndarray((nao_sub, nao_sub), memptr=vtmp_buf.data)
            if xctype == 'LDA':
                aow = _scale_ao(ao_mask, wv[0,p0:p1], out=buf)
                add_sparse(vmat, ao_mask.dot(aow.T, out=vtmp), idx)
            elif xctype == 'GGA':
                aow = _scale_ao(ao_mask, wv[:,p0:p1], out=buf)
                add_sparse(vmat, ao_mask[0].dot(aow.T, out=vtmp), idx)
            elif xctype == 'MGGA':
                vtmp = _tau_dot(ao_mask, ao_mask, wv[4,p0:p1], buf=buf, out=vtmp)
                aow = _scale_ao(ao_mask, wv[:4,p0:p1], out=buf)
                vtmp = contract('ig,jg->ij', ao_mask[0], aow, beta=1., out=vtmp)
                add_sparse(vmat, vtmp, idx)
        vmat = opt.unsort_orbitals(vmat, axis=[0,1])
        if xctype != 'LDA':
            transpose_sum(vmat)
        return nelec, excsum, vmat

    def get_j(mol, auxmol, aux_vec):
        int3c2e_opt = Int3c2eOpt(mol, auxmol).build()
        aux_vec_sorted = cupy.asarray(int3c2e_opt.aux_coeff).dot(cupy.asarray(aux_vec))
        p1 = 0
        J_compressed = 0
        for eri3c in int3c2e_opt.int3c2e_bdiv_generator(batch_size=1200):
            p0, p1 = p1, p1 + eri3c.shape[1]
            J_compressed += eri3c.dot(aux_vec_sorted[p0:p1])
        nao = int3c2e_opt.sorted_mol.nao
        J = cupy.zeros((nao, nao))
        ao_pair_mapping = int3c2e_opt.create_ao_pair_mapping()
        rows, cols = divmod(cupy.asarray(ao_pair_mapping), nao)
        J[rows, cols] = J[cols, rows] = J_compressed
        c = cupy.asarray(int3c2e_opt.coeff)
        return c.T.dot(J).dot(c)

    def get_jk(mol, dm, auxmol, aux_vec):
        vj = get_j(mol, auxmol, aux_vec)
        _, vk = gpu4pyscf.scf.jk.get_jk(mol, dm, 1, with_j=False)
        return vj, vk

    def get_veff(ks, auxmol, aux_vec, dm, mol=None, hermi=1):
        time_stats = {}
        if mol is None: mol = ks.mol
        ni = ks._numint
        if hermi == 2:  # because rho = 0
            n, exc, vxc = 0, 0, 0
        else:
            # no memory check
            # max_memory = ks.max_memory - lib.current_memory()[0]
            t_start = time.time()
            n, exc, vxc = nr_rks(ni._xc_type(ks.xc), mol, ks.xc, auxmol, aux_vec)
            time_stats['grid_eval_time'] = time.time() - t_start
            if ks.do_nlc():
                raise NotImplementedError
        if not ni.libxc.is_hybrid_xc(ks.xc):
            t_start = time.time()
            vj = get_j(mol, auxmol, aux_vec)
            time_stats['get_j_time'] = time.time() - t_start
            vxc += vj
        else:
            omega, alpha, hyb = ni.rsh_and_hybrid_coeff(ks.xc, spin=mol.spin)
            if omega == 0:
                vj, vk = get_jk(mol, dm, auxmol, aux_vec)
                vk *= hyb
            else:
                raise NotImplementedError
            vxc += vj - vk * .5
        return vxc, time_stats

    def int1e1c_analytical(mol):
        """
        Calculate integral values
        .. math:: \int_{-\infty}^{\infty} phi(r) dr
        """
        integral_val = []
        for idx, aug_mom in enumerate(mol._bas[:, 1]):
            if aug_mom == 0:
                exponents = mol.bas_exp(idx)
                norm = (2 * exponents / numpy.pi)**0.75
                coeffs = mol.bas_ctr_coeff(idx)[:, 0]
                integral_val.append(
                    (coeffs * norm * (numpy.pi / exponents)**1.5).sum())
            else:
                integral_val += [0] * (2*aug_mom+1)
        integral_val = numpy.array(integral_val)
        return integral_val

    extra_stats = {}

    if normalize_nelec:
        aux_1c1e = cp.array(int1e1c_analytical(auxmol))
        aux_vec_nelec = aux_vec @ aux_1c1e
        aux_vec *= mol.nelectron / aux_vec_nelec
        extra_stats['aux_vec_nelec'] = aux_vec_nelec.get().item()

    mf = mol.RKS(xc=xc).to_gpu()

    dm_guess = 0
    if mf._numint.libxc.is_hybrid_xc(mf.xc):
        dm_guess = mf.get_init_guess()

    fock, veff_time_stats = get_veff(mf, auxmol, aux_vec, dm_guess)
    fock = fock + mf.get_hcore()
    extra_stats.update(veff_time_stats)

    if transfer_mol is not None:
        fock = cupy.array(transfer_fock(mol, transfer_mol, fock.get()))
        mol = transfer_mol

    t_start = time.time()
    s1e = mol.intor('int1e_ovlp')
    mo_energy, mo_coeff = gpu4pyscf.lib.cupy_helper.eigh(cupy.array(fock), cupy.array(s1e))
    extra_stats['eigh_time'] = time.time() - t_start
    nocc = mol.nelectron // 2
    mocc = mo_coeff[:,:nocc]
    dm0 = mocc.dot(mocc.conj().T) * 2
    dm0_numpy = dm0.get()
    return dm0_numpy, extra_stats


def build_mol_from_data(type_names, aobasis_name, data):
    nuclei = [element_to_atomic_number[type_names[z]] for z in data['z'].cpu().numpy()]
    coords = data['pos'].cpu().numpy()
    mol = pyscf.M(atom=list(zip(nuclei, coords)), basis=aobasis_name)
    return mol


def pred_auxdensity_postprocess(mol, outputs, auxbasis_name, auxbasis, xc, use_denfit_ovlp, normalize_nelec, transfer_mol=None):
    t0 = time.time()
    preds = outputs['output:auxdensity']
    if auxbasis_name.startswith('etb:'):
        beta = float(auxbasis_name.split(':')[-1])
        etb_basis = pyscf.df.aug_etb(mol, beta)
        auxmol = pyscf.df.make_auxmol(mol, auxbasis=etb_basis)
    else:
        auxmol = pyscf.df.make_auxmol(mol, auxbasis=auxbasis_name)
    atom_count_by_elements = {k: 0 for k in preds.keys()}
    atom_vecs = []
    for iatm in range(mol.natm):
        symbol = mol.atom_pure_symbol(iatm)
        atom_vecs.append(preds[symbol][atom_count_by_elements[symbol]])
        atom_count_by_elements[symbol] += 1
    aux_vec = torch.cat(atom_vecs)
    mol_irreps = build_irreps_from_mol(auxmol)
    aux_vec = pyscf_to_standard_perm_D(mol_irreps).T.to(aux_vec) @ aux_vec
    aux_vec = aux_vec.cpu().numpy()
    if use_denfit_ovlp:
        aux_vec = np.linalg.solve(auxmol.intor('int1e_ovlp'), aux_vec)
    t1 = time.time()
    # dm = dm_from_auxdensity(mol, auxmol, xc, aux_vec, normalize_nelec, transfer_mol)
    dm, time_stats = dm_from_auxdensity(mol, auxmol, xc, cp.array(aux_vec), normalize_nelec, transfer_mol)
    time_stats['model_to_auxvec_time'] = t1 - t0
    return dm, time_stats


def pred_fock_postprocess(mol, outputs, ao_prod_basis, normalize_nelec, transfer_mol=None):
    fock = ao_prod_basis.assemble_matrix_from_padded_blocks(mol.atom_charges(), outputs['output:fock_diag_blocks'].cpu().numpy(), outputs['output:fock_tril_blocks'].cpu().numpy())
    fock = ao_prod_basis.transform_from_std_to_pyscf(mol.atom_charges(), fock)

    if transfer_mol is None:
        overlap = mol.intor('int1e_ovlp').astype(np.float32)
        dm = dm_from_fock(mol, overlap, fock)
    else:
        overlap = transfer_mol.intor('int1e_ovlp')
        transfer_fock = transfer_fock(mol, transfer_mol, fock)
        dm = dm_from_fock(transfer_mol, overlap, transfer_fock)

    if normalize_nelec:
        dm *= mol.nelectron / (dm * overlap).sum()

    return dm, {}


def pred_dm_postprocess(mol, outputs, ao_prod_basis, normalize_nelec, transfer_mol=None):
    dm = ao_prod_basis.assemble_matrix_from_padded_blocks(mol.atom_charges(), outputs['output:dm_diag_blocks'].cpu().numpy(), outputs['output:dm_tril_blocks'].cpu().numpy())
    dm = ao_prod_basis.transform_from_std_to_pyscf(mol.atom_charges(), dm)

    if normalize_nelec:
        overlap = mol.intor('int1e_ovlp').astype(np.float32)
        dm *= mol.nelectron / (dm * overlap).sum()
    if transfer_mol is not None:
        raise NotImplementedError
    return dm, {}


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('--ckpt', type=str, help='Path to the checkpoint file')
    parser.add_argument('--gt-mode', action='store_true', help='Use ground truth as initial guess.')
    parser.add_argument('--data-root', default='./dataset/ood-test', type=str, help='Path to the data root directory')
    parser.add_argument('--model-type', default='auxdensity', type=str, choices=['auxdensity', 'dm', 'fock'], help='Prediction type of the model')
    parser.add_argument('--xc', default='PBE', type=str, help='XC functional')
    parser.add_argument('--transfer-basis', default=None, type=str, help='Basis set to which the model prediction is transferred to.')
    parser.add_argument('--with-df', action='store_true', help='Use density fitting for SCF.')
    parser.add_argument('--with-df-basis', default='def2-svp-jkfit', help='The basis set for density fitting in SCF.')
    parser.add_argument('--output', required=True, type=str, help='Path to the output CSV file')
    parser.add_argument('--num-shards', type=int, default=1, help='Number of shards')
    parser.add_argument('--shard-index', default=0, type=int, help='Shard index')
    parser.add_argument('--scf-verbose', action='store_true', help='Print SCF verbose information')
    parser.add_argument('--split', default='no', type=str, choices=['train', 'val', 'test', 'no'], help='Split of the dataset')
    parser.add_argument('--normalize-nelec', action='store_true', help='Normalize the model prediction by number of electrons.')
    args = parser.parse_args()

    if args.ckpt is not None:
        # if a ckpt is provided, use the data config in the ckpt
        ckpt = torch.load(args.ckpt, map_location='cpu', weights_only=True)
        config = ckpt['config']
        data_config = config['data']
        if not args.gt_mode:
            model = nequip_simple_builder(**config['model'])
            model.load_state_dict(ckpt['state_dict'])
            model = model.eval().cuda()
    else:
        assert args.gt_mode, 'Checkpoint path is required in non-gt mode.'
        gt_mode_part = 'auxdensity.denfit' if args.model_type == 'auxdensity' else args.model_type
        data_config = {
            'r_max': 5.0,
            'type_names': ['H', 'C', 'N', 'O', 'F', 'P', 'S'],
            'remove_self_loops': True,
            'parts_to_load': ['base', gt_mode_part],
            'aobasis': 'def2-svp',
            'auxbasis': 'def2-universal-jfit',
            'use_denfit_ovlp': False,
        }

    dataset = SCFBenchDataset(data_root=args.data_root, **data_config)
    if args.split != 'no':
        print(f'Assuming the dataset is SCFbench-main and using indices from scfbench_main_split.npz for split {args.split}...')
        split_file = np.load('./scfbench_main_split.npz')
        dataset_indices = split_file[args.split].tolist()
    else:
        dataset_indices = list(range(len(dataset)))

    dataset_subset_indices = [j for i, j in enumerate(dataset_indices) if i % args.num_shards == args.shard_index]
    dataloader = DataLoader(
        Subset(dataset, dataset_subset_indices),
        batch_size=1,
        shuffle=False,
        num_workers=2,
        collate_fn=dataset.collater,
    )

    aobasis_name, auxbasis_name = data_config['aobasis'], data_config['auxbasis']

    aobasis = GTOBasis.from_basis_name(aobasis_name, elements=data_config['type_names'])
    auxbasis = GTOBasis.from_basis_name(auxbasis_name, elements=data_config['type_names'])
    ao_prod_basis = GTOProductBasisHelper(aobasis)

    use_denfit_ovlp = data_config.get('use_denfit_ovlp', False)

    records = []
    for data in tqdm.tqdm(dataloader):
        data = move_data_to_device(data, 'cuda')

        mol = build_mol_from_data(data_config['type_names'], aobasis_name, data)
        transfer_mol = build_mol_from_data(data_config['type_names'], args.transfer_basis, data) if args.transfer_basis else None

        if not args.gt_mode:
            model_time = 1000.0
            while model_time > 1:
                t0 = time.time()
                with torch.no_grad():
                    outputs = model(data)
                t1 = time.time()
                model_time = t1 - t0
        else:
            if args.model_type == 'auxdensity':
                outputs = {'output:auxdensity': data['auxdensity']}
            elif args.model_type == 'fock':
                outputs = {'output:fock_diag_blocks': data['fock_diag_blocks'], 'output:fock_tril_blocks': data['fock_tril_blocks']}
            elif args.model_type == 'dm':
                outputs = {'output:dm_diag_blocks': data['dm_diag_blocks'], 'output:dm_tril_blocks': data['dm_tril_blocks']}
            model_time = 0.0

        t2 = time.time()

        if args.model_type == 'auxdensity':
            dm, extra_stats = pred_auxdensity_postprocess(mol, outputs, auxbasis_name, auxbasis, args.xc, use_denfit_ovlp, args.normalize_nelec, transfer_mol=transfer_mol)
        elif args.model_type == 'fock':
            dm, extra_stats = pred_fock_postprocess(mol, outputs, ao_prod_basis, args.normalize_nelec, transfer_mol=transfer_mol)
        elif args.model_type == 'dm':
            dm, extra_stats = pred_dm_postprocess(mol, outputs, ao_prod_basis, args.normalize_nelec, transfer_mol=transfer_mol)

        t3 = time.time()

        eval_scf = partial(run_scf_and_count_steps, xc=args.xc, verbose=args.scf_verbose, with_df=args.with_df, with_df_basis=args.with_df_basis)
        if transfer_mol is not None:
            original_energy, original_steps, original_time = eval_scf(transfer_mol, dm0=None)
            accelerated_energy, accelerated_steps, accelerated_time = eval_scf(transfer_mol, dm0=cp.array(dm.astype(np.float64)))  # the type conversion is important here
        else:
            original_energy, original_steps, original_time = eval_scf(mol, dm0=None)
            accelerated_energy, accelerated_steps, accelerated_time = eval_scf(mol, dm0=cp.array(dm.astype(np.float64)))  # the type conversion is important here

        record = {
            'natom': mol.natm,
            'nelec': mol.nelectron,
            'original_steps': original_steps,
            'accelerated_steps': accelerated_steps,
            'original_time': original_time,
            'accelerated_time': accelerated_time,
            'original_energy': original_energy,
            'accelerated_energy': accelerated_energy,
            'model_time': model_time,
            'conversion_time': t3 - t2,
        }
        record.update(extra_stats)
        print(record)
        records.append(record)

        del data, mol, dm, outputs

        if len(records) % 10 == 0:
            df = pd.DataFrame.from_records(records)
            df.to_csv(args.output, index=False)

    df = pd.DataFrame.from_records(records)
    df.to_csv(args.output, index=False)


if __name__ == '__main__':
    main()