from __future__ import annotations

import shutil
import tempfile
import unittest
from pathlib import Path

from engine.artifact_manager import ArtifactManager
from engine.models import (
    ArtifactSpec,
    BudgetSpec,
    LoggingSpec,
    MutationSpec,
    MutatorSpec,
    ObjectiveSpec,
    PolicySpec,
    RunnerSpec,
    ScorerParseSpec,
    ScorerSpec,
    TaskSpec,
)
from engine.mutation_engine import MutationValidationError, validate_candidate_changes


def _make_task(task_root: Path, allowed_file_types: list[str], max_changed_lines: int) -> TaskSpec:
    return TaskSpec(
        id="mutation-test",
        description="Mutation validation fixture.",
        artifacts=ArtifactSpec(include=["fixtures/*"], exclude=[], max_files_per_iteration=10),
        mutation=MutationSpec(
            mode="direct_edit",
            allowed_file_types=allowed_file_types,
            max_changed_lines=max_changed_lines,
        ),
        mutator=MutatorSpec(type="command", command="python -c \"print('mutate')\"", cwd="tasks/demo", timeout_seconds=30),
        runner=RunnerSpec(command="python -c \"print('runner ok')\"", cwd="tasks/demo", timeout_seconds=30),
        scorer=ScorerSpec(
            type="command",
            command="python -c \"print('{\\\"score\\\": 1.0, \\\"metrics\\\": {}}')\"",
            timeout_seconds=30,
            parse=ScorerParseSpec(format="json", score_field="score", metrics_field="metrics"),
        ),
        objective=ObjectiveSpec(primary_metric="score", direction="maximize"),
        constraints=[],
        policy=PolicySpec(keep_if="better_primary", tie_breakers=[], on_failure="discard"),
        budget=BudgetSpec(max_iterations=1, max_failures=1),
        logging=LoggingSpec(results_file="work/results.jsonl", candidate_dir="work/candidates"),
        root_dir=task_root,
    )


class MutationEngineTest(unittest.TestCase):
    def test_rejects_too_many_changed_lines_in_candidate_root(self) -> None:
        with tempfile.TemporaryDirectory() as tmp:
            baseline_root = Path(tmp) / "baseline"
            candidate_root = Path(tmp) / "candidate"
            (baseline_root / "fixtures").mkdir(parents=True)
            (baseline_root / "fixtures" / "note.md").write_text("line 1\nline 2\n", encoding="utf-8")
            shutil.copytree(baseline_root, candidate_root)

            baseline_task = _make_task(baseline_root, allowed_file_types=[".md"], max_changed_lines=1)
            snapshot = ArtifactManager(baseline_task).snapshot()
            (candidate_root / "fixtures" / "note.md").write_text("line 1\nline 2\nline 3\n", encoding="utf-8")

            with self.assertRaises(MutationValidationError) as ctx:
                validate_candidate_changes(baseline_task, snapshot, candidate_root)

            self.assertIn("changed lines", str(ctx.exception))

    def test_rejects_new_file_with_disallowed_extension_in_candidate_root(self) -> None:
        with tempfile.TemporaryDirectory() as tmp:
            baseline_root = Path(tmp) / "baseline"
            candidate_root = Path(tmp) / "candidate"
            (baseline_root / "fixtures").mkdir(parents=True)
            (baseline_root / "fixtures" / "note.md").write_text("line 1\n", encoding="utf-8")
            shutil.copytree(baseline_root, candidate_root)

            baseline_task = _make_task(baseline_root, allowed_file_types=[".md"], max_changed_lines=10)
            snapshot = ArtifactManager(baseline_task).snapshot()
            (candidate_root / "fixtures" / "extra.txt").write_text("new file\n", encoding="utf-8")

            with self.assertRaises(MutationValidationError) as ctx:
                validate_candidate_changes(baseline_task, snapshot, candidate_root)

            self.assertIn("disallowed file type", str(ctx.exception))

    def test_rejects_renamed_file_with_disallowed_extension(self) -> None:
        with tempfile.TemporaryDirectory() as tmp:
            baseline_root = Path(tmp) / "baseline"
            candidate_root = Path(tmp) / "candidate"
            (baseline_root / "fixtures").mkdir(parents=True)
            (baseline_root / "fixtures" / "note.md").write_text("line 1\n", encoding="utf-8")
            shutil.copytree(baseline_root, candidate_root)

            baseline_task = _make_task(baseline_root, allowed_file_types=[".md"], max_changed_lines=10)
            snapshot = ArtifactManager(baseline_task).snapshot()
            (candidate_root / "fixtures" / "note.md").unlink()
            (candidate_root / "fixtures" / "note.txt").write_text("line 1\n", encoding="utf-8")

            with self.assertRaises(MutationValidationError) as ctx:
                validate_candidate_changes(baseline_task, snapshot, candidate_root)

            self.assertIn("disallowed file type", str(ctx.exception))


if __name__ == "__main__":
    unittest.main()