# Copyright (c) Microsoft. All rights reserved.

from typing import TYPE_CHECKING

from semantic_kernel.exceptions.process_exceptions import ProcessInvalidConfigurationException
from semantic_kernel.processes.kernel_process.kernel_process_edge import KernelProcessEdge
from semantic_kernel.processes.process_end_step import EndStep
from semantic_kernel.processes.process_function_target_builder import ProcessFunctionTargetBuilder
from semantic_kernel.utils.feature_stage_decorator import experimental

if TYPE_CHECKING:
    from semantic_kernel.processes.process_step_builder import ProcessStepBuilder


@experimental
class ProcessStepEdgeBuilder:
    """A builder for a process step edge."""

    source: "ProcessStepBuilder"
    target: ProcessFunctionTargetBuilder | None = None
    event_id: str

    def __init__(self, source: "ProcessStepBuilder", event_id: str):
        """Initializes a new instance of ProcessStepEdgeBuilder."""
        self.source = source
        self.event_id = event_id

    def send_event_to(
        self, target: "ProcessFunctionTargetBuilder | ProcessStepBuilder", **kwargs
    ) -> "ProcessStepEdgeBuilder":
        """Sends the event to the target.

        Args:
            target: The target to send the event to.
            **kwargs: Additional keyword arguments.

        Returns:
            ProcessStepEdgeBuilder: The ProcessStepEdgeBuilder instance.
        """
        from semantic_kernel.processes.process_step_builder import ProcessStepBuilder

        if self.target is not None:
            raise ProcessInvalidConfigurationException(
                "An output target has already been set part of the ProcessStepEdgeBuilder."
            )

        if isinstance(target, ProcessStepBuilder):
            target = ProcessFunctionTargetBuilder(
                step=target, parameter_name=kwargs.get("parameter_name"), function_name=kwargs.get("function_name")
            )

        self.target = target
        self.source.link_to(self.event_id, self)

        return ProcessStepEdgeBuilder(source=self.source, event_id=self.event_id)

    def stop_process(self):
        """Stops the process."""
        if self.target is not None:
            raise ProcessInvalidConfigurationException(
                "An output target has already been set part of the ProcessStepEdgeBuilder."
            )
        output_target = ProcessFunctionTargetBuilder(EndStep.get_instance())
        self.target = output_target
        self.source.link_to("END", self)

    def build(self) -> KernelProcessEdge:
        """Builds the KernelProcessEdge."""
        if not self.source.name:
            raise ValueError("Source step must have a valid name")
        if self.target is None:
            raise ValueError("Target must be provided")
        return KernelProcessEdge(source_step_id=self.source.id, output_target=self.target.build())