###########################################################################################
# Data parsing utilities
# Authors: Ilyes Batatia, Gregor Simm and David Kovacs
# This program is distributed under the MIT License (see MIT.md)
###########################################################################################

import logging
from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional, Sequence, Tuple

import ase.data
import ase.io
import h5py
import numpy as np

from mace.tools import AtomicNumberTable, DefaultKeys

Positions = np.ndarray  # [..., 3]
Cell = np.ndarray  # [3,3]
Pbc = tuple  # (3,)

DEFAULT_CONFIG_TYPE = "Default"
DEFAULT_CONFIG_TYPE_WEIGHTS = {DEFAULT_CONFIG_TYPE: 1.0}


@dataclass
class KeySpecification:
    info_keys: Dict[str, str] = field(default_factory=dict)
    arrays_keys: Dict[str, str] = field(default_factory=dict)

    def update(
        self,
        info_keys: Optional[Dict[str, str]] = None,
        arrays_keys: Optional[Dict[str, str]] = None,
    ):
        if info_keys is not None:
            self.info_keys.update(info_keys)
        if arrays_keys is not None:
            self.arrays_keys.update(arrays_keys)
        return self

    @classmethod
    def from_defaults(cls):
        instance = cls()
        return update_keyspec_from_kwargs(instance, DefaultKeys.keydict())


def update_keyspec_from_kwargs(
    keyspec: KeySpecification, keydict: Dict[str, str]
) -> KeySpecification:
    # convert command line style property_key arguments into a keyspec
    infos = ["energy_key", "stress_key", "virials_key", "dipole_key", "head_key"]
    arrays = ["forces_key", "charges_key"]
    info_keys = {}
    arrays_keys = {}
    for key in infos:
        if key in keydict:
            info_keys[key[:-4]] = keydict[key]
    for key in arrays:
        if key in keydict:
            arrays_keys[key[:-4]] = keydict[key]
    keyspec.update(info_keys=info_keys, arrays_keys=arrays_keys)
    return keyspec


@dataclass
class Configuration:
    atomic_numbers: np.ndarray
    positions: Positions  # Angstrom
    properties: Dict[str, Any]
    property_weights: Dict[str, float]
    cell: Optional[Cell] = None
    pbc: Optional[Pbc] = None

    weight: float = 1.0  # weight of config in loss
    config_type: str = DEFAULT_CONFIG_TYPE  # config_type of config
    head: str = "Default"  # head used to compute the config


Configurations = List[Configuration]


def random_train_valid_split(
    items: Sequence, valid_fraction: float, seed: int, work_dir: str
) -> Tuple[List, List]:
    assert 0.0 < valid_fraction < 1.0

    size = len(items)
    train_size = size - int(valid_fraction * size)

    indices = list(range(size))
    rng = np.random.default_rng(seed)
    rng.shuffle(indices)
    if len(indices[train_size:]) < 10:
        logging.info(
            f"Using random {100 * valid_fraction:.0f}% of training set for validation with following indices: {indices[train_size:]}"
        )
    else:
        # Save indices to file
        with open(work_dir + f"/valid_indices_{seed}.txt", "w", encoding="utf-8") as f:
            for index in indices[train_size:]:
                f.write(f"{index}\n")

        logging.info(
            f"Using random {100 * valid_fraction:.0f}% of training set for validation with indices saved in: {work_dir}/valid_indices_{seed}.txt"
        )

    return (
        [items[i] for i in indices[:train_size]],
        [items[i] for i in indices[train_size:]],
    )


def config_from_atoms_list(
    atoms_list: List[ase.Atoms],
    key_specification: KeySpecification,
    config_type_weights: Optional[Dict[str, float]] = None,
    head_name: str = "Default",
) -> Configurations:
    """Convert list of ase.Atoms into Configurations"""
    if config_type_weights is None:
        config_type_weights = DEFAULT_CONFIG_TYPE_WEIGHTS

    all_configs = []
    for atoms in atoms_list:
        all_configs.append(
            config_from_atoms(
                atoms,
                key_specification=key_specification,
                config_type_weights=config_type_weights,
                head_name=head_name,
            )
        )
    return all_configs


def config_from_atoms(
    atoms: ase.Atoms,
    key_specification: KeySpecification = KeySpecification(),
    config_type_weights: Optional[Dict[str, float]] = None,
    head_name: str = "Default",
) -> Configuration:
    """Convert ase.Atoms to Configuration"""
    if config_type_weights is None:
        config_type_weights = DEFAULT_CONFIG_TYPE_WEIGHTS

    atomic_numbers = np.array(
        [ase.data.atomic_numbers[symbol] for symbol in atoms.symbols]
    )
    pbc = tuple(atoms.get_pbc())
    cell = np.array(atoms.get_cell())
    config_type = atoms.info.get("config_type", "Default")
    weight = atoms.info.get("config_weight", 1.0) * config_type_weights.get(
        config_type, 1.0
    )

    properties = {}
    property_weights = {}
    for name in list(key_specification.arrays_keys) + list(key_specification.info_keys):
        property_weights[name] = atoms.info.get(f"config_{name}_weight", 1.0)

    for name, atoms_key in key_specification.info_keys.items():
        properties[name] = atoms.info.get(atoms_key, None)
        if not atoms_key in atoms.info:
            property_weights[name] = 0.0

    for name, atoms_key in key_specification.arrays_keys.items():
        properties[name] = atoms.arrays.get(atoms_key, None)
        if not atoms_key in atoms.arrays:
            property_weights[name] = 0.0

    return Configuration(
        atomic_numbers=atomic_numbers,
        positions=atoms.get_positions(),
        properties=properties,
        weight=weight,
        property_weights=property_weights,
        head=head_name,
        config_type=config_type,
        pbc=pbc,
        cell=cell,
    )


def test_config_types(
    test_configs: Configurations,
) -> List[Tuple[str, List[Configuration]]]:
    """Split test set based on config_type-s"""
    test_by_ct = []
    all_cts = []
    for conf in test_configs:
        config_type_name = conf.config_type + "_" + conf.head
        if config_type_name not in all_cts:
            all_cts.append(config_type_name)
            test_by_ct.append((config_type_name, [conf]))
        else:
            ind = all_cts.index(config_type_name)
            test_by_ct[ind][1].append(conf)
    return test_by_ct


def load_from_xyz(
    file_path: str,
    key_specification: KeySpecification,
    head_name: str = "Default",
    config_type_weights: Optional[Dict] = None,
    extract_atomic_energies: bool = False,
    keep_isolated_atoms: bool = False,
) -> Tuple[Dict[int, float], Configurations]:
    atoms_list = ase.io.read(file_path, index=":")
    energy_key = key_specification.info_keys["energy"]
    forces_key = key_specification.arrays_keys["forces"]
    stress_key = key_specification.info_keys["stress"]
    head_key = key_specification.info_keys["head"]
    if energy_key == "energy":
        logging.warning(
            "Since ASE version 3.23.0b1, using energy_key 'energy' is no longer safe when communicating between MACE and ASE. We recommend using a different key, rewriting 'energy' to 'REF_energy'. You need to use --energy_key='REF_energy' to specify the chosen key name."
        )
        key_specification.info_keys["energy"] = "REF_energy"
        for atoms in atoms_list:
            try:
                atoms.info["REF_energy"] = atoms.get_potential_energy()
            except Exception as e:  # pylint: disable=W0703
                logging.error(f"Failed to extract energy: {e}")
                atoms.info["REF_energy"] = None
    if forces_key == "forces":
        logging.warning(
            "Since ASE version 3.23.0b1, using forces_key 'forces' is no longer safe when communicating between MACE and ASE. We recommend using a different key, rewriting 'forces' to 'REF_forces'. You need to use --forces_key='REF_forces' to specify the chosen key name."
        )
        key_specification.arrays_keys["forces"] = "REF_forces"
        for atoms in atoms_list:
            try:
                atoms.arrays["REF_forces"] = atoms.get_forces()
            except Exception as e:  # pylint: disable=W0703
                logging.error(f"Failed to extract forces: {e}")
                atoms.arrays["REF_forces"] = None
    if stress_key == "stress":
        logging.warning(
            "Since ASE version 3.23.0b1, using stress_key 'stress' is no longer safe when communicating between MACE and ASE. We recommend using a different key, rewriting 'stress' to 'REF_stress'. You need to use --stress_key='REF_stress' to specify the chosen key name."
        )
        key_specification.info_keys["stress"] = "REF_stress"
        for atoms in atoms_list:
            try:
                atoms.info["REF_stress"] = atoms.get_stress()
            except Exception as e:  # pylint: disable=W0703
                atoms.info["REF_stress"] = None
    if not isinstance(atoms_list, list):
        atoms_list = [atoms_list]

    atomic_energies_dict = {}
    if extract_atomic_energies:
        atoms_without_iso_atoms = []

        for idx, atoms in enumerate(atoms_list):
            atoms.info[head_key] = head_name
            isolated_atom_config = (
                len(atoms) == 1 and atoms.info.get("config_type") == "IsolatedAtom"
            )
            if isolated_atom_config:
                atomic_number = int(atoms.get_atomic_numbers()[0])
                if energy_key in atoms.info.keys():
                    atomic_energies_dict[atomic_number] = float(atoms.info[energy_key])
                else:
                    logging.warning(
                        f"Configuration '{idx}' is marked as 'IsolatedAtom' "
                        "but does not contain an energy. Zero energy will be used."
                    )
                    atomic_energies_dict[atomic_number] = 0.0
            else:
                atoms_without_iso_atoms.append(atoms)

        if len(atomic_energies_dict) > 0:
            logging.info("Using isolated atom energies from training file")
        if not keep_isolated_atoms:
            atoms_list = atoms_without_iso_atoms

    for atoms in atoms_list:
        atoms.info[head_key] = head_name

    configs = config_from_atoms_list(
        atoms_list,
        config_type_weights=config_type_weights,
        key_specification=key_specification,
        head_name=head_name,
    )
    return atomic_energies_dict, configs


def compute_average_E0s(
    collections_train: Configurations, z_table: AtomicNumberTable
) -> Dict[int, float]:
    """
    Function to compute the average interaction energy of each chemical element
    returns dictionary of E0s
    """
    len_train = len(collections_train)
    len_zs = len(z_table)
    A = np.zeros((len_train, len_zs))
    B = np.zeros(len_train)
    for i in range(len_train):
        B[i] = collections_train[i].properties["energy"]
        for j, z in enumerate(z_table.zs):
            A[i, j] = np.count_nonzero(collections_train[i].atomic_numbers == z)
    try:
        E0s = np.linalg.lstsq(A, B, rcond=None)[0]
        atomic_energies_dict = {}
        for i, z in enumerate(z_table.zs):
            atomic_energies_dict[z] = E0s[i]
    except np.linalg.LinAlgError:
        logging.error(
            "Failed to compute E0s using least squares regression, using the same for all atoms"
        )
        atomic_energies_dict = {}
        for i, z in enumerate(z_table.zs):
            atomic_energies_dict[z] = 0.0
    return atomic_energies_dict


def save_dataset_as_HDF5(dataset: List, out_name: str) -> None:
    with h5py.File(out_name, "w") as f:
        for i, data in enumerate(dataset):
            save_AtomicData_to_HDF5(data, i, f)


def save_AtomicData_to_HDF5(data, i, h5_file) -> None:
    grp = h5_file.create_group(f"config_{i}")
    grp["num_nodes"] = data.num_nodes
    grp["edge_index"] = data.edge_index
    grp["positions"] = data.positions
    grp["shifts"] = data.shifts
    grp["unit_shifts"] = data.unit_shifts
    grp["cell"] = data.cell
    grp["node_attrs"] = data.node_attrs
    grp["weight"] = data.weight
    grp["energy_weight"] = data.energy_weight
    grp["forces_weight"] = data.forces_weight
    grp["stress_weight"] = data.stress_weight
    grp["virials_weight"] = data.virials_weight
    grp["forces"] = data.forces
    grp["energy"] = data.energy
    grp["stress"] = data.stress
    grp["virials"] = data.virials
    grp["dipole"] = data.dipole
    grp["charges"] = data.charges
    grp["head"] = data.head


def save_configurations_as_HDF5(configurations: Configurations, _, h5_file) -> None:
    grp = h5_file.create_group("config_batch_0")
    for j, config in enumerate(configurations):
        subgroup_name = f"config_{j}"
        subgroup = grp.create_group(subgroup_name)
        subgroup["atomic_numbers"] = write_value(config.atomic_numbers)
        subgroup["positions"] = write_value(config.positions)
        properties_subgrp = subgroup.create_group("properties")
        for key, value in config.properties.items():
            properties_subgrp[key] = write_value(value)
        subgroup["cell"] = write_value(config.cell)
        subgroup["pbc"] = write_value(config.pbc)
        subgroup["weight"] = write_value(config.weight)
        weights_subgrp = subgroup.create_group("property_weights")
        for key, value in config.property_weights.items():
            weights_subgrp[key] = write_value(value)
        subgroup["config_type"] = write_value(config.config_type)


def write_value(value):
    return value if value is not None else "None"
