"""muse#54 item 6 -- `muse reflog stat [--branch <name>] [--json]`.

Summary statistics over a branch's (or HEAD's) reflog: total entries, a
breakdown by operation category, the most active author, a reset count, and
first/last entry timestamps.
"""
from __future__ import annotations

import json
import pathlib

from tests.cli_test_helper import CliRunner
from muse.core.types import fake_id, Manifest
from muse.core.paths import muse_dir

cli = None
runner = CliRunner()


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


def _run(root: pathlib.Path, *args: str):
    return runner.invoke(cli, list(args), env=_env(root))


def _init_repo(tmp_path: pathlib.Path) -> tuple[pathlib.Path, str]:
    dot_muse = muse_dir(tmp_path)
    dot_muse.mkdir()
    repo_id = fake_id("repo")
    (dot_muse / "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")
    (dot_muse / "HEAD").write_text("ref: refs/heads/main\n", encoding="utf-8")
    (dot_muse / "refs" / "heads").mkdir(parents=True)
    (dot_muse / "snapshots").mkdir()
    (dot_muse / "commits").mkdir()
    (dot_muse / "objects").mkdir()
    return tmp_path, repo_id


def _commit_file(root: pathlib.Path, content: str, message: str) -> str:
    (root / "f.txt").write_text(content)
    add = _run(root, "code", "add", "f.txt")
    assert add.exit_code == 0, add.output
    commit = _run(root, "commit", "-m", message, "--json")
    assert commit.exit_code == 0, commit.output
    return json.loads(commit.output)["commit_id"]


class TestReflogStat:
    def test_empty_reflog_reports_zero(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        result = _run(root, "reflog", "stat", "--json")
        assert result.exit_code == 0, result.output
        data = json.loads(result.output)
        assert data["total_entries"] == 0
        assert data["operation_breakdown"] == {}
        assert data["most_active_author"] is None
        assert data["reset_count"] == 0
        assert data["first_timestamp"] is None
        assert data["last_timestamp"] is None

    def test_counts_commits_and_most_active_author(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        _commit_file(root, "v1\n", "c1")
        _commit_file(root, "v2\n", "c2")
        _commit_file(root, "v3\n", "c3")

        result = _run(root, "reflog", "stat", "--json")
        assert result.exit_code == 0, result.output
        data = json.loads(result.output)
        assert data["total_entries"] == 3
        assert data["operation_breakdown"]["commit"] == 3
        assert data["most_active_author"] is not None
        assert data["reset_count"] == 0
        assert data["first_timestamp"] is not None
        assert data["last_timestamp"] is not None
        assert data["first_timestamp"] <= data["last_timestamp"]

    def test_reset_count_tracks_reset_operations(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        _commit_file(root, "v1\n", "c1")
        _commit_file(root, "v2\n", "c2")

        reset_result = _run(root, "reset", "HEAD~1", "--hard", "--json")
        assert reset_result.exit_code == 0, reset_result.output

        result = _run(root, "reflog", "stat", "--json")
        assert result.exit_code == 0, result.output
        data = json.loads(result.output)
        assert data["reset_count"] == 1
        assert data["operation_breakdown"]["reset"] == 1

    def test_branch_flag_targets_named_branch(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        _commit_file(root, "v1\n", "c1")

        result = _run(root, "reflog", "stat", "--branch", "main", "--json")
        assert result.exit_code == 0, result.output
        data = json.loads(result.output)
        assert data["ref"] == "refs/heads/main"
        assert data["total_entries"] == 1

    def test_invalid_branch_name_errors(self, tmp_path: pathlib.Path) -> None:
        root, repo_id = _init_repo(tmp_path)
        _commit_file(root, "v1\n", "c1")

        result = _run(root, "reflog", "stat", "--branch", "../escape", "--json")
        assert result.exit_code == 1