"""Comprehensive tests for ``muse merge``.

Covers:
- E2E: merge fast-forward, merge with conflicts, --format json
- Integration: HEAD updated after merge, conflict state written
- Stress: merge with many files
"""

from __future__ import annotations

type _FileStore = dict[str, bytes]

import datetime
import json
import pathlib
import uuid

import pytest
from tests.cli_test_helper import CliRunner

cli = None  # argparse migration — CliRunner ignores this arg

runner = CliRunner()


# ---------------------------------------------------------------------------
# Shared helpers
# ---------------------------------------------------------------------------

def _env(root: pathlib.Path) -> Manifest:
    return {"MUSE_REPO_ROOT": str(root)}


def _init_repo(tmp_path: pathlib.Path) -> tuple[pathlib.Path, str]:
    muse_dir = tmp_path / ".muse"
    muse_dir.mkdir()
    repo_id = str(uuid.uuid4())
    (muse_dir / "repo.json").write_text(json.dumps({
        "repo_id": repo_id,
        "domain": "code",
        "default_branch": "main",
        "created_at": "2025-01-01T00:00:00+00:00",
    }), encoding="utf-8")
    (muse_dir / "HEAD").write_text("ref: refs/heads/main", encoding="utf-8")
    (muse_dir / "refs" / "heads").mkdir(parents=True)
    (muse_dir / "snapshots").mkdir()
    (muse_dir / "commits").mkdir()
    (muse_dir / "objects").mkdir()
    return tmp_path, repo_id


def _make_commit(root: pathlib.Path, repo_id: str, branch: str = "main",
                 message: str = "test",
                 manifest: Manifest | None = None) -> str:
    from muse.core.store import CommitRecord, SnapshotRecord, write_commit, write_snapshot
    from muse.core.snapshot import compute_snapshot_id, compute_commit_id

    ref_file = root / ".muse" / "refs" / "heads" / branch
    parent_id = ref_file.read_text().strip() if ref_file.exists() else None
    m = manifest or {}
    snap_id = compute_snapshot_id(m)
    committed_at = datetime.datetime.now(datetime.timezone.utc)
    commit_id = compute_commit_id(
        parent_ids=[parent_id] if parent_id else [],
        snapshot_id=snap_id, message=message,
        committed_at_iso=committed_at.isoformat(),
    )
    write_snapshot(root, SnapshotRecord(snapshot_id=snap_id, manifest=m))
    write_commit(root, CommitRecord(
        commit_id=commit_id, repo_id=repo_id, branch=branch,
        snapshot_id=snap_id, message=message, committed_at=committed_at,
        parent_commit_id=parent_id,
    ))
    ref_file.parent.mkdir(parents=True, exist_ok=True)
    ref_file.write_text(commit_id, encoding="utf-8")
    return commit_id


def _write_object(root: pathlib.Path, content: bytes) -> str:
    import hashlib
    obj_id = hashlib.sha256(content).hexdigest()
    obj_path = root / ".muse" / "objects" / obj_id[:2] / obj_id[2:]
    obj_path.parent.mkdir(parents=True, exist_ok=True)
    obj_path.write_bytes(content)
    return obj_id


# ---------------------------------------------------------------------------
# Tests
# ---------------------------------------------------------------------------

class TestMergeCLI:
    def test_merge_branch_into_main(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        base_id = _make_commit(root, repo_id, branch="main", message="base")
        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        obj = _write_object(root, b"feature content")
        _make_commit(root, repo_id, branch="feature", message="feature work",
                     manifest={"new_track.mid": obj})
        result = runner.invoke(cli, ["merge", "feature"], env=_env(root), catch_exceptions=False)
        assert result.exit_code == 0

    def test_merge_nonexistent_branch_fails(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        _make_commit(root, repo_id)
        result = runner.invoke(cli, ["merge", "does-not-exist"], env=_env(root))
        assert result.exit_code != 0

    def test_merge_format_json(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        base_id = _make_commit(root, repo_id, branch="main", message="base")
        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        _make_commit(root, repo_id, branch="feature", message="feat")
        result = runner.invoke(
            cli, ["merge", "--format", "json", "feature"], env=_env(root), catch_exceptions=False
        )
        assert result.exit_code == 0
        data = json.loads(result.output)
        assert isinstance(data, dict)

    def test_merge_message_flag(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        base_id = _make_commit(root, repo_id, branch="main", message="base")
        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        _make_commit(root, repo_id, branch="feature", message="feat")
        result = runner.invoke(
            cli, ["merge", "--message", "Merge feature", "feature"],
            env=_env(root), catch_exceptions=False
        )
        assert result.exit_code == 0

    def test_merge_invalid_branch_name_rejected(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        _make_commit(root, repo_id)
        result = runner.invoke(cli, ["merge", "../evil"], env=_env(root))
        assert result.exit_code != 0

    def test_merge_output_sanitized(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        base_id = _make_commit(root, repo_id, branch="main", message="base")
        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        _make_commit(root, repo_id, branch="feature", message="feat")
        result = runner.invoke(cli, ["merge", "feature"], env=_env(root), catch_exceptions=False)
        assert "\x1b" not in result.output


class TestMergeConflictWorkdir:
    """Regression: non-conflicting additions from theirs must reach the
    working tree even when a conflicted merge exits early.

    Bug: muse merge called ``raise SystemExit`` before ``_restore_from_manifest``
    when conflicts existed.  Theirs-only file additions were computed but never
    written to disk; ``muse checkout --theirs --all`` only resolved the
    conflict_paths, so ``muse code add .`` missed the new files and the merge
    commit was silently incomplete.
    """

    def _make_commit_with_files(
        self,
        root: pathlib.Path,
        repo_id: str,
        branch: str,
        files: _FileStore,
        parent_id: str | None = None,
        message: str = "commit",
    ) -> str:
        manifest: Manifest = {}
        for rel, content in files.items():
            oid = _write_object(root, content)
            manifest[rel] = oid
            dest = root / rel
            dest.parent.mkdir(parents=True, exist_ok=True)
            dest.write_bytes(content)
        return _make_commit(root, repo_id, branch=branch, message=message, manifest=manifest)

    def test_theirs_only_additions_written_to_workdir_on_conflict(
        self, tmp_path: pathlib.Path
    ) -> None:
        """Theirs-only new files must appear in the working tree after a
        conflicted merge so that ``muse code add .`` captures them."""
        root, repo_id = _init_repo(tmp_path)

        # Base: one shared file that both sides will modify (guaranteeing conflict).
        base_id = self._make_commit_with_files(
            root, repo_id, "main",
            {"shared.py": b"def foo(): pass\n"},
            message="base",
        )

        # Theirs: modifies shared.py AND adds two brand-new files.
        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        self._make_commit_with_files(
            root, repo_id, "feature",
            {
                "shared.py": b"def foo(): return 'theirs'\n",
                "new_security_test.py": b"# security test\n",
                "new_perf_test.py": b"# perf test\n",
            },
            message="feature: add tests + modify shared",
        )

        # Ours: also modifies shared.py (guaranteeing a conflict on that file).
        (root / "shared.py").write_bytes(b"def foo(): return 'ours'\n")
        _make_commit(
            root, repo_id, "main", message="ours: modify shared",
            manifest={"shared.py": _write_object(root, b"def foo(): return 'ours'\n")},
        )

        result = runner.invoke(cli, ["merge", "feature"], env=_env(root))

        # Merge must exit with a conflict status, not a clean merge.
        assert result.exit_code != 0, "Expected conflict exit code"
        assert "CONFLICT" in result.output or "conflict" in result.output.lower()

        # The fix: theirs-only additions MUST now exist in the working tree.
        assert (root / "new_security_test.py").exists(), (
            "new_security_test.py (theirs-only addition) must be written to the "
            "working tree even though a conflict was detected on shared.py"
        )
        assert (root / "new_perf_test.py").exists(), (
            "new_perf_test.py (theirs-only addition) must be written to the "
            "working tree even though a conflict was detected on shared.py"
        )
        assert (root / "new_security_test.py").read_bytes() == b"# security test\n"
        assert (root / "new_perf_test.py").read_bytes() == b"# perf test\n"

    def test_conflicting_file_left_at_ours_version_on_conflict(
        self, tmp_path: pathlib.Path
    ) -> None:
        """Conflicting files must remain at their ours content in the working
        tree after a partial restore — the agent resolves via --ours/--theirs."""
        root, repo_id = _init_repo(tmp_path)

        base_id = self._make_commit_with_files(
            root, repo_id, "main",
            {"shared.py": b"def foo(): pass\n"},
            message="base",
        )

        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        self._make_commit_with_files(
            root, repo_id, "feature",
            {
                "shared.py": b"def foo(): return 'theirs'\n",
                "only_on_theirs.py": b"# new\n",
            },
            message="feature",
        )

        ours_content = b"def foo(): return 'ours'\n"
        (root / "shared.py").write_bytes(ours_content)
        _make_commit(
            root, repo_id, "main", message="ours",
            manifest={"shared.py": _write_object(root, ours_content)},
        )

        runner.invoke(cli, ["merge", "feature"], env=_env(root))

        # Conflicting file must stay at ours content for agent inspection.
        assert (root / "shared.py").read_bytes() == ours_content

        # Theirs-only addition must be present.
        assert (root / "only_on_theirs.py").exists()


class TestMergeStress:
    def test_merge_feature_with_many_files(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        base_id = _make_commit(root, repo_id, branch="main", message="base")
        (root / ".muse" / "refs" / "heads" / "feature").write_text(base_id)
        manifest = {f"track_{i:03d}.mid": _write_object(root, f"data {i}".encode())
                    for i in range(30)}
        _make_commit(root, repo_id, branch="feature", message="many files", manifest=manifest)
        result = runner.invoke(cli, ["merge", "feature"], env=_env(root), catch_exceptions=False)
        assert result.exit_code == 0