from __future__ import unicode_literals

from .dag import get_outgoing_edges, topo_sort
from functools import reduce
from ._utils import basestring
import copy
import operator
import subprocess as _subprocess

from ._ffmpeg import (
    input,
    output,
    overwrite_output,
)
from .nodes import (
    get_stream_spec_nodes,
    FilterNode,
    GlobalNode,
    InputNode,
    OutputNode,
    output_operator,
)


def _convert_kwargs_to_cmd_line_args(kwargs):
    args = []
    for k in sorted(kwargs.keys()):
        v = kwargs[k]
        args.append('-{}'.format(k))
        if v is not None:
            args.append('{}'.format(v))
    return args


def _get_input_args(input_node):
    if input_node.name == input.__name__:
        kwargs = copy.copy(input_node.kwargs)
        filename = kwargs.pop('filename')
        fmt = kwargs.pop('format', None)
        video_size = kwargs.pop('video_size', None)
        args = []
        if fmt:
            args += ['-f', fmt]
        if video_size:
            args += ['-video_size', '{}x{}'.format(video_size[0], video_size[1])]
        args += _convert_kwargs_to_cmd_line_args(kwargs)
        args += ['-i', filename]
    else:
        raise ValueError('Unsupported input node: {}'.format(input_node))
    return args


def _format_input_stream_name(stream_name_map, edge):
    prefix = stream_name_map[edge.upstream_node, edge.upstream_label]
    if not edge.upstream_selector:
        suffix = ''
    else:
        suffix = ':{}'.format(edge.upstream_selector)
    return '[{}{}]'.format(prefix, suffix)


def _format_output_stream_name(stream_name_map, edge):
    return '[{}]'.format(stream_name_map[edge.upstream_node, edge.upstream_label])


def _get_filter_spec(node, outgoing_edge_map, stream_name_map):
    incoming_edges = node.incoming_edges
    outgoing_edges = get_outgoing_edges(node, outgoing_edge_map)
    inputs = [_format_input_stream_name(stream_name_map, edge) for edge in incoming_edges]
    outputs = [_format_output_stream_name(stream_name_map, edge) for edge in outgoing_edges]
    filter_spec = '{}{}{}'.format(''.join(inputs), node._get_filter(outgoing_edges), ''.join(outputs))
    return filter_spec


def _allocate_filter_stream_names(filter_nodes, outgoing_edge_maps, stream_name_map):
    stream_count = 0
    for upstream_node in filter_nodes:
        outgoing_edge_map = outgoing_edge_maps[upstream_node]
        for upstream_label, downstreams in list(outgoing_edge_map.items()):
            if len(downstreams) > 1:
                # TODO: automatically insert `splits` ahead of time via graph transformation.
                raise ValueError('Encountered {} with multiple outgoing edges with same upstream label {!r}; a '
                                 '`split` filter is probably required'.format(upstream_node, upstream_label))
            stream_name_map[upstream_node, upstream_label] = 's{}'.format(stream_count)
            stream_count += 1


def _get_filter_arg(filter_nodes, outgoing_edge_maps, stream_name_map):
    _allocate_filter_stream_names(filter_nodes, outgoing_edge_maps, stream_name_map)
    filter_specs = [_get_filter_spec(node, outgoing_edge_maps[node], stream_name_map) for node in filter_nodes]
    return ';'.join(filter_specs)


def _get_global_args(node):
    if node.name == overwrite_output.__name__:
        return ['-y']
    else:
        raise ValueError('Unsupported global node: {}'.format(node))


def _get_output_args(node, stream_name_map):
    if node.name != output.__name__:
        raise ValueError('Unsupported output node: {}'.format(node))
    args = []

    if len(node.incoming_edges) == 0:
        raise ValueError('Output node {} has no mapped streams'.format(node))

    for edge in node.incoming_edges:
        # edge = node.incoming_edges[0]
        stream_name = _format_input_stream_name(stream_name_map, edge)
        if stream_name != '[0]' or len(node.incoming_edges) > 1:
            args += ['-map', stream_name]

    kwargs = copy.copy(node.kwargs)
    filename = kwargs.pop('filename')
    fmt = kwargs.pop('format', None)
    if fmt:
        args += ['-f', fmt]
    args += _convert_kwargs_to_cmd_line_args(kwargs)
    args += [filename]
    return args


@output_operator()
def get_args(stream_spec, overwrite_output=False):
    """Get command-line arguments for ffmpeg."""
    nodes = get_stream_spec_nodes(stream_spec)
    args = []
    # TODO: group nodes together, e.g. `-i somefile -r somerate`.
    sorted_nodes, outgoing_edge_maps = topo_sort(nodes)
    input_nodes = [node for node in sorted_nodes if isinstance(node, InputNode)]
    output_nodes = [node for node in sorted_nodes if isinstance(node, OutputNode)]
    global_nodes = [node for node in sorted_nodes if isinstance(node, GlobalNode)]
    filter_nodes = [node for node in sorted_nodes if isinstance(node, FilterNode)]
    stream_name_map = {(node, None): str(i) for i, node in enumerate(input_nodes)}
    filter_arg = _get_filter_arg(filter_nodes, outgoing_edge_maps, stream_name_map)
    args += reduce(operator.add, [_get_input_args(node) for node in input_nodes])
    if filter_arg:
        args += ['-filter_complex', filter_arg]
    args += reduce(operator.add, [_get_output_args(node, stream_name_map) for node in output_nodes])
    args += reduce(operator.add, [_get_global_args(node) for node in global_nodes], [])
    if overwrite_output:
        args += ['-y']
    return args


@output_operator()
def compile(stream_spec, cmd='ffmpeg', **kwargs):
    """Build command-line for ffmpeg."""
    if isinstance(cmd, basestring):
        cmd = [cmd]
    elif type(cmd) != list:
        cmd = list(cmd)
    return cmd + get_args(stream_spec, **kwargs)


@output_operator()
def run(stream_spec, cmd='ffmpeg', **kwargs):
    """Run ffmpeg on node graph.

    Args:
        **kwargs: keyword-arguments passed to ``get_args()`` (e.g. ``overwrite_output=True``).
    """
    _subprocess.check_call(compile(stream_spec, cmd, **kwargs))


__all__ = [
    'compile',
    'get_args',
    'run',
]