from __future__ import annotations
from typing import Type, Literal

import nodes
import asyncio
import inspect
from comfy_execution.graph_utils import is_link, ExecutionBlocker
from comfy.comfy_types.node_typing import ComfyNodeABC, InputTypeDict, InputTypeOptions

# NOTE: ExecutionBlocker code got moved to graph_utils.py to prevent torch being imported too soon during unit tests
ExecutionBlocker = ExecutionBlocker

class DependencyCycleError(Exception):
    pass

class NodeInputError(Exception):
    pass

class NodeNotFoundError(Exception):
    pass

class DynamicPrompt:
    def __init__(self, original_prompt):
        # The original prompt provided by the user
        self.original_prompt = original_prompt
        # Any extra pieces of the graph created during execution
        self.ephemeral_prompt = {}
        self.ephemeral_parents = {}
        self.ephemeral_display = {}

    def get_node(self, node_id):
        if node_id in self.ephemeral_prompt:
            return self.ephemeral_prompt[node_id]
        if node_id in self.original_prompt:
            return self.original_prompt[node_id]
        raise NodeNotFoundError(f"Node {node_id} not found")

    def has_node(self, node_id):
        return node_id in self.original_prompt or node_id in self.ephemeral_prompt

    def add_ephemeral_node(self, node_id, node_info, parent_id, display_id):
        self.ephemeral_prompt[node_id] = node_info
        self.ephemeral_parents[node_id] = parent_id
        self.ephemeral_display[node_id] = display_id

    def get_real_node_id(self, node_id):
        while node_id in self.ephemeral_parents:
            node_id = self.ephemeral_parents[node_id]
        return node_id

    def get_parent_node_id(self, node_id):
        return self.ephemeral_parents.get(node_id, None)

    def get_display_node_id(self, node_id):
        while node_id in self.ephemeral_display:
            node_id = self.ephemeral_display[node_id]
        return node_id

    def all_node_ids(self):
        return set(self.original_prompt.keys()).union(set(self.ephemeral_prompt.keys()))

    def get_original_prompt(self):
        return self.original_prompt

def get_input_info(
    class_def: Type[ComfyNodeABC],
    input_name: str,
    valid_inputs: InputTypeDict | None = None
) -> tuple[str, Literal["required", "optional", "hidden"], InputTypeOptions] | tuple[None, None, None]:
    """Get the input type, category, and extra info for a given input name.

    Arguments:
        class_def: The class definition of the node.
        input_name: The name of the input to get info for.
        valid_inputs: The valid inputs for the node, or None to use the class_def.INPUT_TYPES().

    Returns:
        tuple[str, str, dict] | tuple[None, None, None]: The input type, category, and extra info for the input name.
    """

    valid_inputs = valid_inputs or class_def.INPUT_TYPES()
    input_info = None
    input_category = None
    if "required" in valid_inputs and input_name in valid_inputs["required"]:
        input_category = "required"
        input_info = valid_inputs["required"][input_name]
    elif "optional" in valid_inputs and input_name in valid_inputs["optional"]:
        input_category = "optional"
        input_info = valid_inputs["optional"][input_name]
    elif "hidden" in valid_inputs and input_name in valid_inputs["hidden"]:
        input_category = "hidden"
        input_info = valid_inputs["hidden"][input_name]
    if input_info is None:
        return None, None, None
    input_type = input_info[0]
    if len(input_info) > 1:
        extra_info = input_info[1]
    else:
        extra_info = {}
    return input_type, input_category, extra_info

class TopologicalSort:
    def __init__(self, dynprompt):
        self.dynprompt = dynprompt
        self.pendingNodes = {}
        self.blockCount = {} # Number of nodes this node is directly blocked by
        self.blocking = {} # Which nodes are blocked by this node
        self.externalBlocks = 0
        self.unblockedEvent = asyncio.Event()

    def get_input_info(self, unique_id, input_name):
        class_type = self.dynprompt.get_node(unique_id)["class_type"]
        class_def = nodes.NODE_CLASS_MAPPINGS[class_type]
        return get_input_info(class_def, input_name)

    def make_input_strong_link(self, to_node_id, to_input):
        inputs = self.dynprompt.get_node(to_node_id)["inputs"]
        if to_input not in inputs:
            raise NodeInputError(f"Node {to_node_id} says it needs input {to_input}, but there is no input to that node at all")
        value = inputs[to_input]
        if not is_link(value):
            raise NodeInputError(f"Node {to_node_id} says it needs input {to_input}, but that value is a constant")
        from_node_id, from_socket = value
        self.add_strong_link(from_node_id, from_socket, to_node_id)

    def add_strong_link(self, from_node_id, from_socket, to_node_id):
        if not self.is_cached(from_node_id):
            self.add_node(from_node_id)
            if to_node_id not in self.blocking[from_node_id]:
                self.blocking[from_node_id][to_node_id] = {}
                self.blockCount[to_node_id] += 1
            self.blocking[from_node_id][to_node_id][from_socket] = True

    def add_node(self, node_unique_id, include_lazy=False, subgraph_nodes=None):
        node_ids = [node_unique_id]
        links = []

        while len(node_ids) > 0:
            unique_id = node_ids.pop()
            if unique_id in self.pendingNodes:
                continue

            self.pendingNodes[unique_id] = True
            self.blockCount[unique_id] = 0
            self.blocking[unique_id] = {}

            inputs = self.dynprompt.get_node(unique_id)["inputs"]
            for input_name in inputs:
                value = inputs[input_name]
                if is_link(value):
                    from_node_id, from_socket = value
                    if subgraph_nodes is not None and from_node_id not in subgraph_nodes:
                        continue
                    _, _, input_info = self.get_input_info(unique_id, input_name)
                    is_lazy = input_info is not None and "lazy" in input_info and input_info["lazy"]
                    if (include_lazy or not is_lazy) and not self.is_cached(from_node_id):
                        node_ids.append(from_node_id)
                        links.append((from_node_id, from_socket, unique_id))

        for link in links:
            self.add_strong_link(*link)

    def add_external_block(self, node_id):
        assert node_id in self.blockCount, "Can't add external block to a node that isn't pending"
        self.externalBlocks += 1
        self.blockCount[node_id] += 1
        def unblock():
            self.externalBlocks -= 1
            self.blockCount[node_id] -= 1
            self.unblockedEvent.set()
        return unblock

    def is_cached(self, node_id):
        return False

    def get_ready_nodes(self):
        return [node_id for node_id in self.pendingNodes if self.blockCount[node_id] == 0]

    def pop_node(self, unique_id):
        del self.pendingNodes[unique_id]
        for blocked_node_id in self.blocking[unique_id]:
            self.blockCount[blocked_node_id] -= 1
        del self.blocking[unique_id]

    def is_empty(self):
        return len(self.pendingNodes) == 0

class ExecutionList(TopologicalSort):
    """
    ExecutionList implements a topological dissolve of the graph. After a node is staged for execution,
    it can still be returned to the graph after having further dependencies added.
    """
    def __init__(self, dynprompt, output_cache):
        super().__init__(dynprompt)
        self.output_cache = output_cache
        self.staged_node_id = None

    def is_cached(self, node_id):
        return self.output_cache.get(node_id) is not None

    async def stage_node_execution(self):
        assert self.staged_node_id is None
        if self.is_empty():
            return None, None, None
        available = self.get_ready_nodes()
        while len(available) == 0 and self.externalBlocks > 0:
            # Wait for an external block to be released
            await self.unblockedEvent.wait()
            self.unblockedEvent.clear()
            available = self.get_ready_nodes()
        if len(available) == 0:
            cycled_nodes = self.get_nodes_in_cycle()
            # Because cycles composed entirely of static nodes are caught during initial validation,
            # we will 'blame' the first node in the cycle that is not a static node.
            blamed_node = cycled_nodes[0]
            for node_id in cycled_nodes:
                display_node_id = self.dynprompt.get_display_node_id(node_id)
                if display_node_id != node_id:
                    blamed_node = display_node_id
                    break
            ex = DependencyCycleError("Dependency cycle detected")
            error_details = {
                "node_id": blamed_node,
                "exception_message": str(ex),
                "exception_type": "graph.DependencyCycleError",
                "traceback": [],
                "current_inputs": []
            }
            return None, error_details, ex

        self.staged_node_id = self.ux_friendly_pick_node(available)
        return self.staged_node_id, None, None

    def ux_friendly_pick_node(self, node_list):
        # If an output node is available, do that first.
        # Technically this has no effect on the overall length of execution, but it feels better as a user
        # for a PreviewImage to display a result as soon as it can
        # Some other heuristics could probably be used here to improve the UX further.
        def is_output(node_id):
            class_type = self.dynprompt.get_node(node_id)["class_type"]
            class_def = nodes.NODE_CLASS_MAPPINGS[class_type]
            if hasattr(class_def, 'OUTPUT_NODE') and class_def.OUTPUT_NODE == True:
                return True
            return False

        # If an available node is async, do that first.
        # This will execute the asynchronous function earlier, reducing the overall time.
        def is_async(node_id):
            class_type = self.dynprompt.get_node(node_id)["class_type"]
            class_def = nodes.NODE_CLASS_MAPPINGS[class_type]
            return inspect.iscoroutinefunction(getattr(class_def, class_def.FUNCTION))

        for node_id in node_list:
            if is_output(node_id) or is_async(node_id):
                return node_id

        #This should handle the VAEDecode -> preview case
        for node_id in node_list:
            for blocked_node_id in self.blocking[node_id]:
                if is_output(blocked_node_id):
                    return node_id

        #This should handle the VAELoader -> VAEDecode -> preview case
        for node_id in node_list:
            for blocked_node_id in self.blocking[node_id]:
                for blocked_node_id1 in self.blocking[blocked_node_id]:
                    if is_output(blocked_node_id1):
                        return node_id

        #TODO: this function should be improved
        return node_list[0]

    def unstage_node_execution(self):
        assert self.staged_node_id is not None
        self.staged_node_id = None

    def complete_node_execution(self):
        node_id = self.staged_node_id
        self.pop_node(node_id)
        self.staged_node_id = None

    def get_nodes_in_cycle(self):
        # We'll dissolve the graph in reverse topological order to leave only the nodes in the cycle.
        # We're skipping some of the performance optimizations from the original TopologicalSort to keep
        # the code simple (and because having a cycle in the first place is a catastrophic error)
        blocked_by = { node_id: {} for node_id in self.pendingNodes }
        for from_node_id in self.blocking:
            for to_node_id in self.blocking[from_node_id]:
                if True in self.blocking[from_node_id][to_node_id].values():
                    blocked_by[to_node_id][from_node_id] = True
        to_remove = [node_id for node_id in blocked_by if len(blocked_by[node_id]) == 0]
        while len(to_remove) > 0:
            for node_id in to_remove:
                for to_node_id in blocked_by:
                    if node_id in blocked_by[to_node_id]:
                        del blocked_by[to_node_id][node_id]
                del blocked_by[node_id]
            to_remove = [node_id for node_id in blocked_by if len(blocked_by[node_id]) == 0]
        return list(blocked_by.keys())
