import numpy as np

import hail as hl
from hail.typecheck import typecheck, oneof, nullable
from hail.expr.expressions import expr_locus, expr_float64, check_row_indexed
from hail.utils.java import Env


@typecheck(a=np.ndarray,
           radius=oneof(int, float))
def array_windows(a, radius):
    """Returns start and stop indices for window around each array value.

    Examples
    --------

    >>> hl.linalg.utils.array_windows(np.array([1, 2, 4, 4, 6, 8]), 2)
    (array([0, 0, 1, 1, 2, 4]), array([2, 4, 5, 5, 6, 6]))

    >>> hl.linalg.utils.array_windows(np.array([-10.0, -2.5, 0.0, 0.0, 1.2, 2.3, 3.0]), 2.5)
    (array([0, 1, 1, 1, 2, 2, 4]), array([1, 4, 6, 6, 7, 7, 7]))

    Notes
    -----
    For an array ``a`` in ascending order, the resulting ``starts`` and ``stops``
    arrays have the same length as ``a`` and the property that, for all indices
    ``i``, ``[starts[i], stops[i])`` is the maximal range of indices ``j`` such
    that ``a[i] - radius <= a[j] <= a[i] + radius``.

    Index ranges are start-inclusive and stop-exclusive. This function is
    especially useful in conjunction with
    :meth:`.BlockMatrix.sparsify_row_intervals`.

    Parameters
    ----------
    a: :obj:`numpy.ndarray` of signed integer or float values
        1-dimensional array of values, non-decreasing with respect to index.
    radius: :obj:`float`
        Non-negative radius of window for values.

    Returns
    -------
    (:class:`numpy.ndarray` of :obj:`int`, :class:`numpy.ndarray` of :obj:`int`)
        Tuple of start indices array and stop indices array.
    """
    if radius < 0:
        raise ValueError(f'array_windows: radius must be non-negative, found {radius}')
    if a.ndim != 1:
        raise ValueError("array_windows: 'a' must be 1-dimensional")
    if not (np.issubdtype(a.dtype, np.signedinteger) or np.issubdtype(a.dtype, np.floating)):
        raise ValueError(f"array_windows: 'a' must be an ndarray of signed integer or float values, "
                         f"found dtype {str(a.dtype)}")

    size = a.size
    if size == 0:
        return np.zeros(shape=0, dtype=np.int64), np.zeros(shape=0, dtype=np.int64)

    if (not np.all(a[:-1] <= a[1:])) or np.isnan(a[0]):
        raise ValueError("array_windows: 'a' must be in ascending order with no nan elements")
    if a[0] - radius > a[0]:
        raise ValueError('array_windows: underflow for a[0] - radius')
    if a[-1] + radius < a[-1]:
        raise ValueError('array_windows: overflow for a[-1] + radius')

    starts, stops = np.zeros(size, dtype=np.int64), np.zeros(size, dtype=np.int64)
    j, k = 0, 0
    for i in range(size):
        min_val = a[i] - radius
        while j < size and a[j] < min_val:
            j += 1
        starts[i] = j

        max_val = a[i] + radius
        while k < size and a[k] <= max_val:
            k += 1
        stops[i] = k

    return starts, stops


@typecheck(locus_expr=expr_locus(),
           radius=oneof(int, float),
           coord_expr=nullable(expr_float64),
           _localize=bool)
def locus_windows(locus_expr, radius, coord_expr=None, _localize=True):
    """Returns start and stop indices for window around each locus.

    Examples
    --------

    Windows with 2bp radius for one contig with positions 1, 2, 3, 4, 5:

    >>> starts, stops = hl.linalg.utils.locus_windows(
    ...     hl.balding_nichols_model(1, 5, 5).locus,
    ...     radius=2)
    >>> starts, stops
    (array([0, 0, 0, 1, 2]), array([3, 4, 5, 5, 5]))

    The following examples involve three contigs.

    >>> loci = [{'locus': hl.Locus('1', 1), 'cm': 1.0},
    ...         {'locus': hl.Locus('1', 2), 'cm': 3.0},
    ...         {'locus': hl.Locus('1', 4), 'cm': 4.0},
    ...         {'locus': hl.Locus('2', 1), 'cm': 2.0},
    ...         {'locus': hl.Locus('2', 1), 'cm': 2.0},
    ...         {'locus': hl.Locus('3', 3), 'cm': 5.0}]

    >>> ht = hl.Table.parallelize(
    ...         loci,
    ...         hl.tstruct(locus=hl.tlocus('GRCh37'), cm=hl.tfloat64),
    ...         key=['locus'])

    Windows with 1bp radius:

    >>> hl.linalg.utils.locus_windows(ht.locus, 1)
    (array([0, 0, 2, 3, 3, 5]), array([2, 2, 3, 5, 5, 6]))

    Windows with 1cm radius:

    >>> hl.linalg.utils.locus_windows(ht.locus, 1.0, coord_expr=ht.cm)
    (array([0, 1, 1, 3, 3, 5]), array([1, 3, 3, 5, 5, 6]))

    Notes
    -----
    This function returns two 1-dimensional ndarrays of integers,
    ``starts`` and ``stops``, each of size equal to the number of rows.

    By default, for all indices ``i``, ``[starts[i], stops[i])`` is the maximal
    range of row indices ``j`` such that ``contig[i] == contig[j]`` and
    ``position[i] - radius <= position[j] <= position[i] + radius``.

    If the :meth:`.global_position` on `locus_expr` is not in ascending order,
    this method will fail. Ascending order should hold for a matrix table keyed
    by locus or variant (and the associated row table), or for a table that has
    been ordered by `locus_expr`.

    Set `coord_expr` to use a value other than position to define the windows.
    This row-indexed numeric expression must be non-missing, non-``nan``, on the
    same source as `locus_expr`, and ascending with respect to locus
    position for each contig; otherwise the function will fail.

    The last example above uses centimorgan coordinates, so
    ``[starts[i], stops[i])`` is the maximal range of row indices ``j`` such
    that ``contig[i] == contig[j]`` and
    ``cm[i] - radius <= cm[j] <= cm[i] + radius``.

    Index ranges are start-inclusive and stop-exclusive. This function is
    especially useful in conjunction with
    :meth:`.BlockMatrix.sparsify_row_intervals`.

    Parameters
    ----------
    locus_expr : :class:`.LocusExpression`
        Row-indexed locus expression on a table or matrix table.
    radius: :obj:`int`
        Radius of window for row values.
    coord_expr: :class:`.Float64Expression`, optional
        Row-indexed numeric expression for the row value.
        Must be on the same table or matrix table as `locus_expr`.
        By default, the row value is given by the locus position.

    Returns
    -------
    (:class:`numpy.ndarray` of :obj:`int`, :class:`numpy.ndarray` of :obj:`int`)
        Tuple of start indices array and stop indices array.
    """
    if radius < 0:
        raise ValueError(f"locus_windows: 'radius' must be non-negative, found {radius}")
    check_row_indexed('locus_windows', locus_expr)
    if coord_expr is not None:
        check_row_indexed('locus_windows', coord_expr)

    src = locus_expr._indices.source
    if locus_expr not in src._fields_inverse:
        locus = Env.get_uid()
        annotate_fields = {locus: locus_expr}

        if coord_expr is not None:
            if coord_expr not in src._fields_inverse:
                coords = Env.get_uid()
                annotate_fields[coords] = coord_expr
            else:
                coords = src._fields_inverse[coord_expr]

        if isinstance(src, hl.MatrixTable):
            new_src = src.annotate_rows(**annotate_fields)
        else:
            new_src = src.annotate(**annotate_fields)

        locus_expr = new_src[locus]
        if coord_expr is not None:
            coord_expr = new_src[coords]

    if coord_expr is None:
        coord_expr = locus_expr.position

    rg = locus_expr.dtype.reference_genome
    contig_group_expr = hl.agg.group_by(hl.locus(locus_expr.contig, 1, reference_genome=rg), hl.agg.collect(coord_expr))

    # check loci are in sorted order
    last_pos = hl.fold(lambda a, elt: (hl.case()
                                         .when(a <= elt, elt)
                                         .or_error("locus_windows: 'locus_expr' global position must be in ascending order.")),
                       -1,
                       hl.agg.collect(hl.case()
                                        .when(hl.is_defined(locus_expr), locus_expr.global_position())
                                        .or_error("locus_windows: missing value for 'locus_expr'.")))
    checked_contig_groups = (hl.case()
                               .when(last_pos >= 0, contig_group_expr)
                               .or_error("locus_windows: 'locus_expr' has length 0"))

    contig_groups = locus_expr._aggregation_method()(checked_contig_groups, _localize=False)

    coords = hl.sorted(hl.array(contig_groups)).map(lambda t: t[1])
    starts_and_stops = hl._locus_windows_per_contig(coords, radius)

    if not _localize:
        return starts_and_stops

    starts, stops = hl.eval(starts_and_stops)
    return np.array(starts), np.array(stops)


def _check_dims(a, name, ndim, min_size=1):
    if len(a.shape) != ndim:
        raise ValueError(f'{name} must be {ndim}-dimensional, '
                         f'found {a.ndim}')
    for i in range(ndim):
        if a.shape[i] < min_size:
            raise ValueError(f'{name}.shape[{i}] must be at least '
                             f'{min_size}, found {a.shape[i]}')


def _ndarray_matmul_ndim(left, right):
    if left == 1 and right == 1:
        return 0
    elif left == 1:
        return right - 1
    elif right == 1:
        return left - 1
    else:
        assert left == right
        return left
