"""ORCH-071 — post-deploy merge verification + rollout conditionality.

Covers TC-01..04 (FR-2/G1/AC-1/AC-7: verify_merged_to_main), TC-11 (AC-4b: non-self
repo no-op) and TC-12 (AC-10: kill-switch). All deterministic: git/HTTP are mocked,
the verifier honours the never-raise contract.
"""

import pytest

from src import merge_gate


class _R:
    """Minimal stand-in for a completed subprocess result (returncode only)."""

    def __init__(self, rc):
        self.returncode = rc
        self.stdout = ""
        self.stderr = ""


@pytest.fixture(autouse=True)
def _enable(monkeypatch):
    # The conftest disables the under-gate by default; these tests target it, so
    # re-enable the feature and pin the scope to self-hosting only (empty CSV).
    monkeypatch.setattr(merge_gate.settings, "merge_verify_enabled", True)
    monkeypatch.setattr(merge_gate.settings, "merge_verify_repos", "")
    monkeypatch.setattr(merge_gate.settings, "merge_verify_timeout_s", 5)


# ---------------------------------------------------------------------------
# TC-01: validated SHA is an ancestor of origin/main (merge-base rc=0) -> True.
# ---------------------------------------------------------------------------
def test_tc01_verify_true_when_sha_is_ancestor(monkeypatch):
    monkeypatch.setattr(merge_gate, "pr_already_merged", lambda r, b: False)
    monkeypatch.setattr(merge_gate, "ensure_worktree", lambda r, b: "/wt")

    calls = []

    def fake_run(cmd, *a, **k):
        calls.append(cmd)
        # fetch -> rc 0; merge-base --is-ancestor -> rc 0 (is ancestor).
        return _R(0)

    monkeypatch.setattr(merge_gate.subprocess, "run", fake_run)
    assert merge_gate.verify_merged_to_main("orchestrator", "feature/ORCH-071-x", "abc123") is True
    # The verifier consulted git merge-base --is-ancestor on origin/main.
    assert any("merge-base" in c and "--is-ancestor" in c and "origin/main" in c for c in calls)


# ---------------------------------------------------------------------------
# TC-02 (ORCH-073 FR-1): PR.merged==true NO LONGER confirms a merge. The former
# OR-branch was the phantom-merge root cause (a merged docs-PR turned verify green).
# SHA-in-main is now the SINGLE criterion; an empty SHA -> inconclusive -> False.
# ---------------------------------------------------------------------------
def test_tc02_pr_merged_does_not_confirm_without_sha_in_main(monkeypatch):
    # Even if a (docs-)PR is reported merged, that must NOT short-circuit to True.
    monkeypatch.setattr(merge_gate, "pr_already_merged", lambda r, b: True)
    monkeypatch.setattr(merge_gate, "ensure_worktree", lambda r, b: "/wt")
    # SHA not an ancestor of origin/main (rc=1) -> not confirmed despite merged PR.
    monkeypatch.setattr(
        merge_gate.subprocess, "run",
        lambda cmd, *a, **k: _R(1) if "merge-base" in cmd else _R(0),
    )
    assert merge_gate.verify_merged_to_main("orchestrator", "feature/ORCH-071-x", "abc123") is False
    # And an empty SHA is inconclusive -> False (cannot prove SHA-in-main).
    assert merge_gate.verify_merged_to_main("orchestrator", "feature/ORCH-071-x", "") is False


# ---------------------------------------------------------------------------
# TC-03: not an ancestor (rc=1) AND PR not merged -> False (phantom merge).
# ---------------------------------------------------------------------------
def test_tc03_verify_false_when_phantom(monkeypatch):
    monkeypatch.setattr(merge_gate, "pr_already_merged", lambda r, b: False)
    monkeypatch.setattr(merge_gate, "ensure_worktree", lambda r, b: "/wt")

    def fake_run(cmd, *a, **k):
        if "merge-base" in cmd:
            return _R(1)  # NOT an ancestor.
        return _R(0)  # fetch ok.

    monkeypatch.setattr(merge_gate.subprocess, "run", fake_run)
    assert merge_gate.verify_merged_to_main("orchestrator", "feature/ORCH-071-x", "abc123") is False


# ---------------------------------------------------------------------------
# TC-04 (AC-7): never-raise — a git/OS error -> False, exception not propagated.
# ---------------------------------------------------------------------------
def test_tc04_verify_never_raises_on_git_error(monkeypatch):
    monkeypatch.setattr(merge_gate, "pr_already_merged", lambda r, b: False)
    monkeypatch.setattr(merge_gate, "ensure_worktree", lambda r, b: "/wt")

    def boom(*a, **k):
        raise OSError("git exploded")

    monkeypatch.setattr(merge_gate.subprocess, "run", boom)
    # No exception escapes; the conservative verdict is "not confirmed".
    assert merge_gate.verify_merged_to_main("orchestrator", "feature/ORCH-071-x", "abc123") is False


def test_tc04_verify_never_raises_on_worktree_error(monkeypatch):
    # ORCH-073: verify no longer consults pr_already_merged; a worktree/git error
    # on the SHA-in-main path is the failure to swallow -> conservative False.
    def boom(*a, **k):
        raise RuntimeError("worktree exploded")

    monkeypatch.setattr(merge_gate, "ensure_worktree", boom)
    assert merge_gate.verify_merged_to_main("orchestrator", "feature/ORCH-071-x", "abc123") is False


# ---------------------------------------------------------------------------
# TC-11 (AC-4b): non-self repo -> under-gate is a no-op (merge stays with deployer).
# ---------------------------------------------------------------------------
def test_tc11_non_self_repo_does_not_apply(monkeypatch):
    # Empty CSV -> only the self-hosting repo is in scope.
    assert merge_gate.merge_verify_applies("orchestrator") is True
    assert merge_gate.merge_verify_applies("enduro-trails") is False


def test_tc11_csv_scopes_to_listed_repos(monkeypatch):
    monkeypatch.setattr(merge_gate.settings, "merge_verify_repos", "enduro-trails")
    assert merge_gate.merge_verify_applies("enduro-trails") is True
    # When the CSV is set, the self repo is NOT auto-included.
    assert merge_gate.merge_verify_applies("orchestrator") is False


# ---------------------------------------------------------------------------
# TC-12 (AC-10): kill-switch off -> applies False for everyone (1:1 prior behaviour).
# ---------------------------------------------------------------------------
def test_tc12_kill_switch_disables_under_gate(monkeypatch):
    monkeypatch.setattr(merge_gate.settings, "merge_verify_enabled", False)
    assert merge_gate.merge_verify_applies("orchestrator") is False
    assert merge_gate.merge_verify_applies("enduro-trails") is False