import networkx
from packaging.version import parse as parse_version


from ..inittask import validate_task_executable
from .analysis import required_predecessors
from .schema import (
    LATEST_VERSION,
    normalize_schema_version,
    update_graph_schema,
)


def validate_graph(graph: networkx.DiGraph) -> None:
    normalize_schema_version(graph)
    while parse_version(graph.graph["schema_version"]) != LATEST_VERSION:
        update_graph_schema(graph)
    _validate_nodes(graph)
    _validate_links(graph)


def _validate_nodes(graph: networkx.DiGraph) -> None:
    for node_id, node_attrs in graph.nodes.items():
        validate_task_executable(node_id, node_attrs)

        # Isolated nodes do no harm so comment this
        # if len(graph.nodes) > 1 and not node_has_links(graph, node_id):
        #    raise ValueError(f"Node {repr(node_id)} has no links")

        inputs_from_required = dict()
        for source_id in required_predecessors(graph, node_id):
            link_attrs = graph[source_id][node_id]
            arguments = link_attrs.get("data_mapping", list())
            for arg in arguments:
                try:
                    name = arg["target_input"]
                except KeyError:
                    raise KeyError(
                        f"Argument '{arg}' of link '{source_id}' -> '{node_id}' is missing a 'target_input' key"
                    ) from None
                other_source_id = inputs_from_required.get(name)
                if other_source_id:
                    raise ValueError(
                        f"Node {repr(source_id)} and {repr(other_source_id)} both connect to the input {repr(name)} of {repr(node_id)}"
                    )
                inputs_from_required[name] = source_id


def _validate_links(graph: networkx.DiGraph) -> None:
    for (source, target), linkattrs in graph.edges.items():
        err_msg = f"Link {source}->{target}: '{{}}' and '{{}}' cannot be used together"
        if linkattrs.get("map_all_data") and linkattrs.get("data_mapping"):
            raise ValueError(err_msg.format("map_all_data", "data_mapping"))
        if linkattrs.get("on_error") and linkattrs.get("conditions"):
            raise ValueError(err_msg.format("on_error", "conditions"))