"""Supercharge tests for ``muse merge-base``.

Coverage tiers
--------------
- JSON envelope: exit_code and duration_ms present on found and not-found outcomes
- Error payload: errors go to stdout as JSON in --json mode, no dual stderr prose
- Data integrity: symmetry (A,B)==(B,A); merge-commit as input; deep DAG
- TypedDicts: _MergeBaseFoundJson and _MergeBaseErrorJson with required annotations
- Docstring: module docstring covers exit_code and duration_ms
- No-prose pollution: no emoji / prose leaks into JSON stdout
- Stress: 100-commit linear chain resolves correctly
"""
from __future__ import annotations
from collections.abc import Mapping

import argparse
import datetime
import json
import pathlib
from typing import get_type_hints

from muse.core.types import fake_id
from muse.core.ids import hash_commit as compute_commit_id, hash_snapshot as compute_snapshot_id
from muse.core.commits import (
    CommitRecord,
    write_commit,
)
from muse.core.snapshots import (
    SnapshotRecord,
    write_snapshot,
)
from muse.core.paths import head_path, muse_dir, ref_path
from tests.cli_test_helper import CliRunner, InvokeResult

runner = CliRunner()

_DT = datetime.datetime(2026, 1, 1, tzinfo=datetime.timezone.utc)


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _init_repo(tmp_path: pathlib.Path) -> pathlib.Path:
    muse = muse_dir(tmp_path)
    for sub in ("objects", "commits", "snapshots", "refs/heads"):
        (muse / sub).mkdir(parents=True)
    (muse / "HEAD").write_text("ref: refs/heads/main", encoding="utf-8")
    (muse / "repo.json").write_text(
        json.dumps({"repo_id": "supercharge-test", "domain": "code"}),
        encoding="utf-8",
    )
    return tmp_path


def _env(root: pathlib.Path) -> Mapping[str, str]:
    return {"MUSE_REPO_ROOT": str(root)}


def _snap(root: pathlib.Path) -> str:
    sid = compute_snapshot_id({})
    write_snapshot(root, SnapshotRecord(snapshot_id=sid, manifest={}, created_at=_DT))
    return sid


def _commit(
    root: pathlib.Path,
    msg: str,
    *,
    parent: str | None = None,
    parent2: str | None = None,
    branch: str = "main",
) -> str:
    sid = _snap(root)
    parent_ids = [p for p in [parent, parent2] if p is not None]
    cid = compute_commit_id(
        parent_ids=parent_ids,
        snapshot_id=sid,
        message=msg,
        committed_at_iso=_DT.isoformat(),
    )
    write_commit(root, CommitRecord(
        commit_id=cid,
        branch=branch,
        snapshot_id=sid,
        message=msg,
        committed_at=_DT,
        parent_commit_id=parent,
        parent2_commit_id=parent2,
    ))
    return cid


def _set_branch(root: pathlib.Path, branch: str, cid: str) -> None:
    ref = ref_path(root, branch)
    ref.parent.mkdir(parents=True, exist_ok=True)
    ref.write_text(cid, encoding="utf-8")
    (head_path(root)).write_text(f"ref: refs/heads/{branch}", encoding="utf-8")


def _mb(root: pathlib.Path, *args: str) -> InvokeResult:
    from muse.cli.app import main as cli
    return runner.invoke(cli, ["merge-base", *args], env=_env(root))


def _mbj(root: pathlib.Path, *args: str) -> InvokeResult:
    """Like _mb but always passes --json."""
    return _mb(root, "--json", *args)


def _diverged_repo(root: pathlib.Path) -> tuple[str, str, str]:
    """Create base → left and base → right. Returns (base, left, right)."""
    base = _commit(root, "base")
    left = _commit(root, "left", parent=base, branch="left")
    right = _commit(root, "right", parent=base, branch="right")
    _set_branch(root, "left", left)
    _set_branch(root, "right", right)
    return base, left, right


def _unrelated_repo(root: pathlib.Path) -> tuple[str, str]:
    """Two commits with no shared history."""
    c1 = _commit(root, "unrelated-c1")
    c2 = _commit(root, "unrelated-c2")
    return c1, c2


# ---------------------------------------------------------------------------
# JSON envelope — exit_code
# ---------------------------------------------------------------------------


class TestJsonEnvelopeExitCode:
    """exit_code is present and correct on all merge-base outcomes."""

    def test_found_has_exit_code(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        r = _mbj(root, left, right)
        assert r.exit_code == 0
        d = json.loads(r.output)
        assert "exit_code" in d, "exit_code missing when merge base is found"
        assert d["exit_code"] == 0

    def test_not_found_has_exit_code(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        c1, c2 = _unrelated_repo(root)
        r = _mbj(root, c1, c2)
        assert r.exit_code == 0
        d = json.loads(r.output)
        assert "exit_code" in d, "exit_code missing when no common ancestor"
        assert d["exit_code"] == 0

    def test_same_commit_has_exit_code(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        cid = _commit(root, "solo")
        r = _mbj(root, cid, cid)
        d = json.loads(r.output)
        assert "exit_code" in d
        assert d["exit_code"] == 0


# ---------------------------------------------------------------------------
# JSON envelope — duration_ms
# ---------------------------------------------------------------------------


class TestJsonEnvelopeDurationMs:
    """duration_ms is present and non-negative on all merge-base outcomes."""

    def test_found_has_duration_ms(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        r = _mbj(root, left, right)
        d = json.loads(r.output)
        assert "duration_ms" in d, "duration_ms missing when merge base is found"
        assert isinstance(d["duration_ms"], float)
        assert d["duration_ms"] >= 0.0

    def test_not_found_has_duration_ms(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        c1, c2 = _unrelated_repo(root)
        r = _mbj(root, c1, c2)
        d = json.loads(r.output)
        assert "duration_ms" in d, "duration_ms missing when no common ancestor"
        assert isinstance(d["duration_ms"], float)

    def test_same_commit_has_duration_ms(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        cid = _commit(root, "dur-solo")
        r = _mbj(root, cid, cid)
        d = json.loads(r.output)
        assert "duration_ms" in d
        assert isinstance(d["duration_ms"], float)


# ---------------------------------------------------------------------------
# Error payload — errors route to stdout as JSON in --json mode
# ---------------------------------------------------------------------------


class TestErrorPayload:
    """In --json mode, all errors appear on stdout as JSON — no stderr prose."""

    def test_bad_ref_error_is_json_on_stdout(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        r = _mbj(root, "no-such-branch", "also-missing")
        assert r.exit_code != 0
        # Error JSON must go to stdout: stderr should be empty.
        assert not r.stderr.strip(), f"unexpected stderr: {r.stderr!r}"
        d = json.loads(r.output)
        assert d["status"] == "error"

    def test_bad_ref_error_has_status_error(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        r = _mbj(root, "ghost", "phantom")
        d = json.loads(r.output)
        assert d["status"] == "error"

    def test_bad_ref_error_has_exit_code(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        r = _mbj(root, "ghost", "phantom")
        d = json.loads(r.output)
        assert "exit_code" in d
        assert d["exit_code"] != 0

    def test_bad_ref_error_has_error_field(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        r = _mbj(root, "ghost", "phantom")
        d = json.loads(r.output)
        assert "error" in d
        assert d["error"]  # non-empty message

    def test_no_duplicate_stderr_prose(self, tmp_path: pathlib.Path) -> None:
        """In --json mode, errors must not also print ❌ prose to stderr."""
        root = _init_repo(tmp_path)
        r = _mbj(root, "no-such", "branch")
        assert "❌" not in r.stderr

    def test_second_bad_ref_error_is_json_on_stdout(self, tmp_path: pathlib.Path) -> None:
        """Error on second ref (commit_b) also goes to stdout, not stderr."""
        root = _init_repo(tmp_path)
        cid = _commit(root, "real-commit")
        r = _mbj(root, cid, "nonexistent")
        assert r.exit_code != 0
        assert not r.stderr.strip(), f"unexpected stderr: {r.stderr!r}"
        d = json.loads(r.output)
        assert d["status"] == "error"


# ---------------------------------------------------------------------------
# Data integrity
# ---------------------------------------------------------------------------


class TestDataIntegrity:
    """Correctness properties that must hold across all inputs."""

    def test_symmetry(self, tmp_path: pathlib.Path) -> None:
        """merge-base(A, B) == merge-base(B, A)."""
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        r_ab = json.loads(_mbj(root, left, right).output)
        r_ba = json.loads(_mbj(root, right, left).output)
        assert r_ab["merge_base"] == r_ba["merge_base"]

    def test_merge_commit_as_input(self, tmp_path: pathlib.Path) -> None:
        """A merge commit (two parents) is handled correctly as input."""
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        # Simulate a merge commit that has both left and right as parents
        merge_commit = _commit(root, "merge", parent=left, parent2=right, branch="main")
        _set_branch(root, "main", merge_commit)
        # merge-base of the merge commit with right should be right (right is ancestor of merge)
        r = _mbj(root, merge_commit, right)
        assert r.exit_code == 0
        d = json.loads(r.output)
        assert d["merge_base"] == right

    def test_found_merge_base_is_correct(self, tmp_path: pathlib.Path) -> None:
        """merge_base field equals the actual LCA commit ID."""
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        d = json.loads(_mbj(root, left, right).output)
        assert d["merge_base"] == base

    def test_commit_a_and_b_echoed_correctly(self, tmp_path: pathlib.Path) -> None:
        """commit_a and commit_b in the response match what was requested."""
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        d = json.loads(_mbj(root, left, right).output)
        assert d["commit_a"] == left
        assert d["commit_b"] == right

    def test_not_found_merge_base_is_null(self, tmp_path: pathlib.Path) -> None:
        """merge_base is null (not absent) when no common ancestor."""
        root = _init_repo(tmp_path)
        c1, c2 = _unrelated_repo(root)
        d = json.loads(_mbj(root, c1, c2).output)
        assert "merge_base" in d
        assert d["merge_base"] is None


# ---------------------------------------------------------------------------
# No-prose pollution
# ---------------------------------------------------------------------------


class TestNoProsePollution:
    """JSON stdout must be valid, parseable JSON on all non-error paths."""

    def test_found_stdout_is_valid_json(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        r = _mbj(root, left, right)
        json.loads(r.output)  # must not raise

    def test_not_found_stdout_is_valid_json(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        c1, c2 = _unrelated_repo(root)
        json.loads(_mbj(root, c1, c2).output)  # must not raise

    def test_no_emoji_in_found_json(self, tmp_path: pathlib.Path) -> None:
        root = _init_repo(tmp_path)
        base, left, right = _diverged_repo(root)
        r = _mbj(root, left, right)
        assert "✅" not in r.output
        assert "❌" not in r.output


# ---------------------------------------------------------------------------
# TypedDicts
# ---------------------------------------------------------------------------


class TestTypedDicts:
    def test_merge_base_found_json_typeddict_exists(self) -> None:
        from muse.cli.commands.merge_base import _MergeBaseFoundJson
        assert _MergeBaseFoundJson is not None

    def test_merge_base_error_json_typeddict_exists(self) -> None:
        from muse.cli.commands.merge_base import _MergeBaseErrorJson
        assert _MergeBaseErrorJson is not None

    def test_merge_base_found_json_has_exit_code_annotation(self) -> None:
        from muse.cli.commands.merge_base import _MergeBaseFoundJson
        hints = get_type_hints(_MergeBaseFoundJson)
        assert "exit_code" in hints

    def test_merge_base_found_json_has_duration_ms_annotation(self) -> None:
        from muse.cli.commands.merge_base import _MergeBaseFoundJson
        hints = get_type_hints(_MergeBaseFoundJson)
        assert "duration_ms" in hints

    def test_merge_base_error_json_has_required_fields(self) -> None:
        from muse.cli.commands.merge_base import _MergeBaseErrorJson
        hints = get_type_hints(_MergeBaseErrorJson)
        for field in ("status", "error", "exit_code"):
            assert field in hints, f"Missing annotation: {field!r}"


# ---------------------------------------------------------------------------
# Docstring coverage
# ---------------------------------------------------------------------------


class TestDocstring:
    def _doc(self) -> str:
        import muse.cli.commands.merge_base as mod
        return mod.__doc__ or ""

    def test_docstring_documents_exit_code(self) -> None:
        assert "exit_code" in self._doc()

    def test_docstring_documents_duration_ms(self) -> None:
        assert "duration_ms" in self._doc()


# ---------------------------------------------------------------------------
# Stress
# ---------------------------------------------------------------------------


class TestStress:
    def test_100_commit_linear_chain(self, tmp_path: pathlib.Path) -> None:
        """100-commit chain: merge-base of tip and midpoint is the midpoint."""
        root = _init_repo(tmp_path)
        commits: list[str] = []
        for i in range(100):
            parent = commits[-1] if commits else None
            cid = _commit(root, f"chain-{i:03d}", parent=parent)
            commits.append(cid)
        mid = commits[49]
        tip = commits[-1]
        r = _mbj(root, tip, mid)
        assert r.exit_code == 0
        d = json.loads(r.output)
        assert d["merge_base"] == mid
        assert "duration_ms" in d
        assert "exit_code" in d


class TestRegisterFlags:
    def _parse(self, *args: str) -> "argparse.Namespace":
        import argparse
        from muse.cli.commands.merge_base import register
        p = argparse.ArgumentParser()
        subs = p.add_subparsers()
        register(subs)
        return p.parse_args(["merge-base", fake_id("a"), fake_id("b"), *args])

    def test_json_short_flag(self) -> None:
        args = self._parse("-j")
        assert args.json_out is True

    def test_json_long_flag(self) -> None:
        args = self._parse("--json")
        assert args.json_out is True

    def test_default_no_json(self) -> None:
        args = self._parse()
        assert args.json_out is False