from __future__ import annotations

from collections.abc import Mapping, Sequence
from typing import Any

from langgraph._internal._constants import RESERVED
from langgraph.channels.base import BaseChannel
from langgraph.managed.base import ManagedValueMapping
from langgraph.pregel._read import PregelNode
from langgraph.types import All


def validate_graph(
    nodes: Mapping[str, PregelNode],
    channels: dict[str, BaseChannel],
    managed: ManagedValueMapping,
    input_channels: str | Sequence[str],
    output_channels: str | Sequence[str],
    stream_channels: str | Sequence[str] | None,
    interrupt_after_nodes: All | Sequence[str],
    interrupt_before_nodes: All | Sequence[str],
) -> None:
    for chan in channels:
        if chan in RESERVED:
            raise ValueError(f"Channel name '{chan}' is reserved")
    for name in managed:
        if name in RESERVED:
            raise ValueError(f"Managed name '{name}' is reserved")

    subscribed_channels = set[str]()
    for name, node in nodes.items():
        if name in RESERVED:
            raise ValueError(f"Node name '{name}' is reserved")
        if isinstance(node, PregelNode):
            subscribed_channels.update(node.triggers)
            if isinstance(node.channels, str):
                if node.channels not in channels:
                    raise ValueError(
                        f"Node {name} reads channel '{node.channels}' "
                        f"not in known channels: '{repr(sorted(channels))[:100]}'"
                    )
            else:
                for chan in node.channels:
                    if chan not in channels and chan not in managed:
                        raise ValueError(
                            f"Node {name} reads channel '{chan}' "
                            f"not in known channels: '{repr(sorted(channels))[:100]}'"
                        )
        else:
            raise TypeError(
                f"Invalid node type {type(node)}, expected PregelNode or NodeBuilder"
            )

    for chan in subscribed_channels:
        if chan not in channels:
            raise ValueError(
                f"Subscribed channel '{chan}' not "
                f"in known channels: '{repr(sorted(channels))[:100]}'"
            )

    if isinstance(input_channels, str):
        if input_channels not in channels:
            raise ValueError(
                f"Input channel '{input_channels}' not "
                f"in known channels: '{repr(sorted(channels))[:100]}'"
            )
        if input_channels not in subscribed_channels:
            raise ValueError(
                f"Input channel {input_channels} is not subscribed to by any node"
            )
    else:
        for chan in input_channels:
            if chan not in channels:
                raise ValueError(
                    f"Input channel '{chan}' not in '{repr(sorted(channels))[:100]}'"
                )
        if all(chan not in subscribed_channels for chan in input_channels):
            raise ValueError(
                f"None of the input channels {input_channels} "
                f"are subscribed to by any node"
            )

    all_output_channels = set[str]()
    if isinstance(output_channels, str):
        all_output_channels.add(output_channels)
    else:
        all_output_channels.update(output_channels)
    if isinstance(stream_channels, str):
        all_output_channels.add(stream_channels)
    elif stream_channels is not None:
        all_output_channels.update(stream_channels)

    for chan in all_output_channels:
        if chan not in channels:
            raise ValueError(
                f"Output channel '{chan}' not "
                f"in known channels: '{repr(sorted(channels))[:100]}'"
            )

    if interrupt_after_nodes != "*":
        for n in interrupt_after_nodes:
            if n not in nodes:
                raise ValueError(f"Node {n} not in nodes")
    if interrupt_before_nodes != "*":
        for n in interrupt_before_nodes:
            if n not in nodes:
                raise ValueError(f"Node {n} not in nodes")


def validate_keys(
    keys: str | Sequence[str] | None,
    channels: Mapping[str, Any],
) -> None:
    if isinstance(keys, str):
        if keys not in channels:
            raise ValueError(f"Key {keys} not in channels")
    elif keys is not None:
        for chan in keys:
            if chan not in channels:
                raise ValueError(f"Key {chan} not in channels")