import string
import warnings
import collections
import numpy as np


__all__ = [
    'InputVariable',
]

_SPECIAL_DATASET_INDICES = (':', '+', '?')

_DATASET_INDICES = ''.join(list(string.digits) + list(_SPECIAL_DATASET_INDICES))

_INTERNAL_DATASET_INDICES = ('__s', '__i', '__a')

_SPECIAL_CONVERSION = zip(_INTERNAL_DATASET_INDICES, _SPECIAL_DATASET_INDICES)

_UNITS = {
    'bohr': 1.0,
    'angstrom': 1.8897261328856432,
    'hartree': 1.0,
    'Ha': 1.0,
    'eV': 0.03674932539796232,
}


class InputVariable(object):
    """
    An Abinit input variable.
    """
    def __init__(self, name, value, units='', valperline=3):

        self._name = name
        self.value = value
        self._units = units

        # Maximum number of values per line.
        self.valperline = valperline
        if name in ['bdgw']:
            self.valperline = 2

        if (is_iter(self.value) and isinstance(self.value[-1], str) and self.value[-1] in _UNITS):
            self.value = list(self.value)
            self._units = self.value.pop(-1)

    def get_value(self):
        """Return the value."""
        if self.units:
            return list(self.value) + [self.units]
        else:
            return self.value

    @property
    def name(self):
        return self._name

    @property
    def basename(self):
        """Return the name trimmed of any dataset index."""
        basename = self.name
        return basename.rstrip(_DATASET_INDICES)

    @property
    def dataset(self):
        """Return the dataset index in string form."""
        return self.name.split(self.basename)[-1]

    @property
    def units(self):
        """Return the units."""
        return self._units

    def __str__(self):
        """Declaration of the variable in the input file."""
        value = self.value
        if value is None or not str(value):
            return ''

        var = self.name
        line = ' ' + var

        # By default, do not impose a number of decimal points
        floatdecimal = 0

        # For some inputs, enforce number of decimal points...
        if any(inp in var for inp in ('xred', 'xcart', 'rprim', 'qpt', 'kpt')):
            floatdecimal = 16

        # ...but not for those
        if any(inp in var for inp in ('ngkpt', 'kptrlatt', 'ngqpt', 'ng2qpt')):
            floatdecimal = 0

        if isinstance(value, np.ndarray):
            n = 1
            for i in np.shape(value):
                n *= i
            value = np.reshape(value, n)
            value = list(value)

        # values in lists
        if isinstance(value, (list, tuple)):

            # Reshape a list of lists into a single list
            if all(isinstance(v, (list, tuple)) for v in value):
                line += self.format_list2d(value, floatdecimal)

            else:
                line += self.format_list(value, floatdecimal)

        # scalar values
        else:
            line += ' ' + str(value)

        # Add units
        if self.units:
            line += ' ' + self.units

        return line

    def format_scalar(self, val, floatdecimal=0):
        """
        Format a single numerical value into a string
        with the appropriate number of decimal.
        """
        sval = str(val)
        if sval.lstrip('-').lstrip('+').isdigit() and floatdecimal == 0:
            return sval

        try:
            fval = float(val)
        except Exception:
            return sval

        if fval == 0 or (abs(fval) > 1e-3 and abs(fval) < 1e4):
            form = 'f'
            addlen = 5
        else:
            form = 'e'
            addlen = 8

        ndec = max(len(str(fval-int(fval)))-2, floatdecimal)
        ndec = min(ndec, 10)

        sval = '{v:>{l}.{p}{f}}'.format(v=fval, l=ndec+addlen, p=ndec, f=form)

        sval = sval.replace('e', 'd')

        return sval

    def format_list2d(self, values, floatdecimal=0):
        """Format a list of lists."""
        lvals = flatten(values)

        # Determine the representation
        if all(isinstance(v, int) for v in lvals):
            type_all = int
        else:
            try:
                for v in lvals:
                    float(v)
                type_all = float
            except Exception:
                type_all = str

        # Determine the format
        width = max(len(str(s)) for s in lvals)
        if type_all == int:
            formatspec = '>{0}d'.format(width)
        elif type_all == str:
            formatspec = '>{0}'.format(width)
        else:

            # Number of decimal
            maxdec = max(len(str(f-int(f)))-2 for f in lvals)
            ndec = min(max(maxdec, floatdecimal), 10)

            if all(f == 0 or (abs(f) > 1e-3 and abs(f) < 1e4) for f in lvals):
                formatspec = '>{w}.{p}f'.format(w=ndec+5, p=ndec)
            else:
                formatspec = '>{w}.{p}e'.format(w=ndec+8, p=ndec)

        line = '\n'
        for L in values:
            for val in L:
                line += ' {v:{f}}'.format(v=val, f=formatspec)
            line += '\n'

        return line.rstrip('\n')

    def format_list(self, values, floatdecimal=0):
        """
        Format a list of values into a string.
        The result might be spread among several lines.
        """
        line = ''

        # Format the line declaring the value
        for i, val in enumerate(values):
            line += ' ' + self.format_scalar(val, floatdecimal)
            if self.valperline is not None and (i+1) % self.valperline == 0:
                line += '\n'

        # Add a carriage return in case of several lines
        if '\n' in line.rstrip('\n'):
            line = '\n' + line

        return line.rstrip('\n')


def is_iter(obj):
    """Return True if the argument is list-like."""
    return hasattr(obj, '__iter__')


def flatten(iterable):
    """Make an iterable flat, i.e. a 1d iterable object."""
    iterator = iter(iterable)
    array, stack = collections.deque(), collections.deque()
    while True:
        try:
            value = next(iterator)
        except StopIteration:
            if not stack:
                return tuple(array)
            iterator = stack.pop()
        else:
            if not isinstance(value, str) \
               and isinstance(value, collections.Iterable):
                stack.append(iterator)
                iterator = iter(value)
            else:
                array.append(value)
