from __future__ import annotations

import pytest
from pydantic import ValidationError

from gap_pipeline.models import (
    DiffusedProof,
    MethodPlan,
    ProofDAG,
    ReplacementSpec,
)


def test_valid_dag_and_plan(dag_dict: dict, plan_dict: dict) -> None:
    dag = ProofDAG.model_validate(dag_dict)
    assert [node.node_id for node in dag.topological_nodes()] == ["n1", "n2"]
    assert dag.leaf_node_ids() == ["n1"]
    plan = MethodPlan.model_validate(plan_dict)
    plan.validate_against(dag)


def test_cycle_is_rejected(dag_dict: dict) -> None:
    dag_dict["nodes"][0]["dependencies"] = ["n2"]
    with pytest.raises(ValidationError, match="cycle"):
        ProofDAG.model_validate(dag_dict)


def test_node_disconnected_from_terminal_is_rejected(dag_dict: dict) -> None:
    dag_dict["nodes"].append(
        {
            "node_id": "orphan",
            "claim": "unused claim",
            "derivation": "unused derivation",
            "dependencies": [],
            "source_span": "",
            "mathematical_objects": [],
        }
    )
    with pytest.raises(ValidationError, match="disconnected"):
        ProofDAG.model_validate(dag_dict)


def test_method_reordering_is_rejected(dag_dict: dict, plan_dict: dict) -> None:
    dag = ProofDAG.model_validate(dag_dict)
    plan_dict["steps"].reverse()
    plan = MethodPlan.model_validate(plan_dict)
    with pytest.raises(ValueError, match="topological order"):
        plan.validate_against(dag)


def test_replacement_must_target_leaf(
    dag_dict: dict, replacement_dict: dict
) -> None:
    dag = ProofDAG.model_validate(dag_dict)
    replacement_dict["target_node_id"] = "n2"
    replacement = ReplacementSpec.model_validate(replacement_dict)
    with pytest.raises(ValueError, match="not a DAG leaf"):
        replacement.validate_against(dag)


def test_diffusion_cannot_change_dag_dependencies(
    dag_dict: dict,
    plan_dict: dict,
    diffused_dict: dict,
) -> None:
    dag = ProofDAG.model_validate(dag_dict)
    plan = MethodPlan.model_validate(plan_dict)
    diffused_dict["node_instantiations"][1]["dependencies"] = []
    diffused = DiffusedProof.model_validate(diffused_dict)
    with pytest.raises(ValueError, match="changes dependencies"):
        diffused.validate_against(dag, plan)