import os
from pathlib import Path
import subprocess
import unittest

import yaml


class PruningContract(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.action = yaml.safe_load((Path(__file__).resolve().parents[1] / "action.yaml").read_text())
        cls.steps = cls.action["runs"]["steps"]

    def test_default_preserves_existing_callers_and_only_prune_is_conditional(self):
        self.assertEqual(self.action["inputs"]["prune"]["default"], "true")
        gated = [step for step in self.steps if "if" in step]
        self.assertEqual(len(gated), 1)
        self.assertEqual(gated[0]["name"], "Prune old tags")
        self.assertEqual(gated[0]["if"], "${{ inputs.prune == 'true' }}")
        remote = [step for step in self.steps if "/packages/" in step.get("run", "")]
        self.assertEqual(remote, gated)
        self.assertIn("docker push", next(step for step in self.steps if step["name"] == "Push")["run"])
        self.assertNotIn("if", next(step for step in self.steps if step["name"] == "Untag local image"))

    def test_invalid_policy_stops_before_credential_step(self):
        validation = self.steps[0]
        self.assertEqual(validation["name"], "Validate pruning policy")
        self.assertEqual(validation["env"], {"PRUNE": "${{ inputs.prune }}"})
        self.assertNotIn("uses", validation)
        for value, success in (("true", True), ("false", True), ("False", False), ("", False), ("yes", False), ("false\ntrue", False)):
            with self.subTest(value=value):
                result = subprocess.run(["bash", "-c", validation["run"]], env={"PATH": os.defpath, "PRUNE": value}, capture_output=True)
                self.assertEqual(result.returncode == 0, success)


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