import io
import subprocess
from pathlib import Path
from typing import Any

import pytest

from nisse_dev.execution import SSHHost
from nisse_dev.git import GitRepo
from nisse_dev.gitea import GiteaError, PullRequest
from nisse_dev.oplog import OpLog
from nisse_dev.publish import OPEN_PR_INTENT, MilestonePublisher
from nisse_dev.state import StateStore

# The build VM for every test here: the session's throwaway sshd.
HOST: SSHHost


@pytest.fixture(autouse=True)
def _build_host(ssh_host: SSHHost) -> None:
    global HOST
    HOST = ssh_host


class FakeGitea:
    def __init__(self, *, fail: bool = False) -> None:
        self.opened: list[dict[str, Any]] = []
        self.existing: list[str] = []
        self.closed: set[str] = set()
        self._fail = fail

    def open_pull_request(
        self, repo: str, *, head: str, base: str, title: str, body: str
    ) -> PullRequest:
        if self._fail:
            raise GiteaError("gitea is down")
        self.opened.append(
            {"repo": repo, "head": head, "base": base, "title": title, "body": body}
        )
        self.existing.append(head)
        return PullRequest(
            number=len(self.opened), state="open", head=head, url=f"u/{head}"
        )

    def find_pull_request(self, repo: str, head: str) -> PullRequest | None:
        if head in self.existing:
            state = "closed" if head in self.closed else "open"
            return PullRequest(number=1, state=state, head=head, url="u")
        return None


class FakeGit:
    """A real repository whose origin/main is a local ref; pushes are
    recorded, not sent."""

    def __init__(
        self, root: Path, *, changes: bool = True, committed: bool = False
    ) -> None:
        self.repo = GitRepo(HOST, root)
        self.repo.init()
        self.repo.configure_identity("bot", "bot@example.test")
        (root / "README.md").write_text("sandbox")
        self.repo.commit_all("Initial commit")
        git(root, "update-ref", "refs/remotes/origin/main", "HEAD")
        if changes:
            (root / "work.txt").write_text("done")
        if committed:
            # The executor committing its own work, as on the first live run.
            self.repo.commit_all("Add the work")
        self.pushed: list[str] = []
        self.remote: dict[str, str] = {}

    def head_sha(self) -> str:
        return self.repo.head_sha()

    def commits_since(self, ref: str) -> int:
        return self.repo.commits_since(ref)

    def remote_sha(
        self, remote_url: str, branch: str, *, key: str | None = None
    ) -> str | None:
        return self.remote.get(branch)

    def current_branch(self) -> str:
        return self.repo.current_branch()

    def checkout_new_branch(self, name: str) -> None:
        self.repo.checkout_new_branch(name)

    def commit_all(self, message: str) -> str | None:
        return self.repo.commit_all(message)

    def push(self, remote_url: str, branch: str, *, key: str | None = None) -> None:
        self.pushed.append(branch)
        self.remote[branch] = self.repo.head_sha()


def git(root: Path, *args: str) -> None:
    subprocess.run(["git", *args], cwd=root, check=True, capture_output=True)


@pytest.fixture
def store(tmp_path: Path) -> StateStore:
    return StateStore(tmp_path / "state.db", oplog=OpLog("nisse-dev", io.StringIO()))


def build(store: StateStore, git: Any, client: Any) -> MilestonePublisher:
    return MilestonePublisher(
        store,
        client,
        "o/sandbox",
        git,
        remote_url="ssh://git@gitea.test/o/sandbox.git",
        push_key="KEY",
    )


def test_publish_commits_pushes_and_opens_a_pr(
    store: StateStore, tmp_path: Path
) -> None:
    git = FakeGit(tmp_path / "work")
    client = FakeGitea()
    result = build(store, git, client).publish(
        task_id="demo-abc", milestone=2, project="demo", plan="the plan"
    )

    assert git.pushed == ["demo-abc/milestone-2"]
    assert client.opened[0]["head"] == "demo-abc/milestone-2"
    assert client.opened[0]["base"] == "main"
    assert "the plan" in client.opened[0]["body"]
    assert result.pull_request is not None
    assert "opened PR #1" in result.note


def test_intent_is_recorded_then_committed(store: StateStore, tmp_path: Path) -> None:
    build(store, FakeGit(tmp_path / "work"), FakeGitea()).publish(
        task_id="t", milestone=1, project="demo", plan="p"
    )
    # Nothing left pending: the intent opened before the push was settled
    # once the PR existed.
    assert store.pending_intents() == []


def test_failure_after_intent_leaves_it_pending_for_reconciliation(
    store: StateStore, tmp_path: Path
) -> None:
    publisher = build(store, FakeGit(tmp_path / "work"), FakeGitea(fail=True))
    with pytest.raises(GiteaError):
        publisher.publish(task_id="t", milestone=1, project="demo", plan="p")

    [pending] = store.pending_intents()
    assert pending.kind == OPEN_PR_INTENT
    assert pending.payload["branch"] == "t/milestone-1"
    assert pending.payload["sha"]


def test_nothing_to_commit_is_reported_not_raised(
    store: StateStore, tmp_path: Path
) -> None:
    git = FakeGit(tmp_path / "work", changes=False)
    client = FakeGitea()
    result = build(store, git, client).publish(
        task_id="t", milestone=1, project="demo", plan="p"
    )
    assert result.pull_request is None
    assert result.note == "no changes to publish"
    assert client.opened == []
    # No externally visible act was attempted, so no intent was opened.
    assert store.pending_intents() == []


def test_branch_is_namespaced_by_task(store: StateStore, tmp_path: Path) -> None:
    publisher = build(store, FakeGit(tmp_path / "work"), FakeGitea())
    assert publisher.branch_for("greet-9f2", 3) == "greet-9f2/milestone-3"


def test_reconciler_settles_an_intent_left_by_a_crash(
    store: StateStore, tmp_path: Path
) -> None:
    # Simulate the dangerous window: the PR was opened, but the process died
    # before the intent could be committed. On the next boot the reconciler
    # must say "already done" so the milestone is not published twice.
    client = FakeGitea()
    publisher = build(store, FakeGit(tmp_path / "work"), client)
    intent_id = store.begin_intent(
        OPEN_PR_INTENT, {"branch": "t/milestone-1"}, cause="crash simulation"
    )
    client.existing.append("t/milestone-1")

    reconcilers = publisher.reconcilers()
    assert set(reconcilers) == {OPEN_PR_INTENT}
    [pending] = store.pending_intents()
    assert reconcilers[OPEN_PR_INTENT](pending) is True

    store.commit_intent(intent_id, cause="verified")
    assert client.opened == []  # nothing re-published


def test_work_the_executor_committed_itself_is_published(
    store: StateStore, tmp_path: Path
) -> None:
    git = FakeGit(tmp_path / "work", committed=True)
    client = FakeGitea()
    result = build(store, git, client).publish(
        task_id="t", milestone=1, project="demo", plan="p"
    )
    assert result.pull_request is not None
    assert git.pushed == ["t/milestone-1"]
    assert git.remote["t/milestone-1"] == git.head_sha()


def test_a_followup_the_executor_committed_itself_is_pushed(
    store: StateStore, tmp_path: Path
) -> None:
    git = FakeGit(tmp_path / "work")
    publisher = build(store, git, FakeGitea())
    publisher.publish(task_id="t", milestone=1, project="demo", plan="p")
    (tmp_path / "work" / "work.txt").write_text("fixed")
    git.repo.commit_all("Address review")
    sha = publisher.push_followup(task_id="t", milestone=1, message="m")
    assert sha == git.head_sha()
    assert git.pushed == ["t/milestone-1", "t/milestone-1"]
    # Nothing new since that push: no second push, and it says so.
    assert publisher.push_followup(task_id="t", milestone=1, message="m") is None
    assert len(git.pushed) == 2


def test_publishing_again_adopts_the_open_pr_instead_of_opening_another(
    store: StateStore, tmp_path: Path
) -> None:
    # E.g. Gitea opened the PR but the response was lost, and the milestone
    # was published again: the PR is adopted and updated, never duplicated.
    git = FakeGit(tmp_path / "work")
    client = FakeGitea()
    publisher = build(store, git, client)
    publisher.publish(task_id="t", milestone=1, project="demo", plan="p")
    (tmp_path / "work" / "more.txt").write_text("more")
    result = publisher.publish(task_id="t", milestone=1, project="demo", plan="p")
    assert len(client.opened) == 1
    assert result.pull_request is not None and result.pull_request.number == 1
    assert "already open" in result.note
    assert git.pushed == ["t/milestone-1", "t/milestone-1"]  # updated it
    assert store.pending_intents() == []


def test_a_closed_pr_is_not_adopted(store: StateStore, tmp_path: Path) -> None:
    git = FakeGit(tmp_path / "work")
    client = FakeGitea()
    client.existing.append("t/milestone-1")
    client.closed.add("t/milestone-1")
    publisher = build(store, git, client)
    assert publisher.published_pull_request("t", 1) is None
    publisher.publish(task_id="t", milestone=1, project="demo", plan="p")
    assert len(client.opened) == 1  # the operator closed it; a new one opens