"""Tests for synthetic database schema introspection utilities."""

from __future__ import annotations

import json
import sqlite3
from pathlib import Path

import pytest

from sql_env.server.synthetic.generate import (
    VariantResult,
    generate_variant,
    generate_variants_for_question,
)
from sql_env.server.synthetic.__main__ import main as synthetic_cli_main
from sql_env.server.synthetic.mutations import (
    MutationResult,
    TableSchema,
    detect_bridge_tables,
    duplicate_bridge_rows,
    get_table_schemas,
    inject_irrelevant_rows,
    remap_ids,
)
from sql_env.server.synthetic.validate import validate_gold_sql


def _sqlite_table_definitions(db_path: Path) -> list[tuple[str, str]]:
    with sqlite3.connect(db_path) as connection:
        cursor = connection.cursor()
        cursor.execute(
            "SELECT name, sql FROM sqlite_master "
            "WHERE type = 'table' AND name NOT LIKE 'sqlite_%' ORDER BY name"
        )
        return [(str(row[0]), str(row[1])) for row in cursor.fetchall()]


def _find_real_spider_case() -> tuple[Path, str, str] | None:
    repo_root = Path(__file__).resolve().parents[1]
    question_files = [
        repo_root / "data" / "questions" / "questions_train.json",
        repo_root / "data" / "questions" / "questions_eval.json",
    ]

    for question_file in question_files:
        if not question_file.exists():
            continue

        questions = json.loads(question_file.read_text(encoding="utf-8"))
        for question in questions:
            db_name = question.get("database_name")
            gold_sql = question.get("gold_sql")
            if not isinstance(db_name, str) or not isinstance(gold_sql, str):
                continue

            db_path = repo_root / "data" / "databases" / db_name / f"{db_name}.sqlite"
            if not db_path.exists():
                continue

            try:
                is_valid, _ = validate_gold_sql(str(db_path), gold_sql)
            except sqlite3.OperationalError:
                continue

            if is_valid:
                return db_path, gold_sql, db_name

    return None


@pytest.fixture
def sample_db_path(tmp_path):
    db_path = tmp_path / "sample.sqlite"
    with sqlite3.connect(db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("PRAGMA foreign_keys = ON")

        cursor.execute(
            "CREATE TABLE departments (id INTEGER PRIMARY KEY, name TEXT NOT NULL)"
        )
        cursor.execute(
            "CREATE TABLE employees ("
            "id INTEGER PRIMARY KEY,"
            "name TEXT NOT NULL,"
            "department_id INTEGER,"
            "FOREIGN KEY(department_id) REFERENCES departments(id)"
            ")"
        )
        cursor.execute(
            "CREATE TABLE students (id INTEGER PRIMARY KEY, name TEXT NOT NULL)"
        )
        cursor.execute(
            "CREATE TABLE courses (id INTEGER PRIMARY KEY, title TEXT NOT NULL)"
        )
        cursor.execute(
            "CREATE TABLE enrollments ("
            "student_id INTEGER,"
            "course_id INTEGER,"
            "PRIMARY KEY(student_id, course_id),"
            "FOREIGN KEY(student_id) REFERENCES students(id),"
            "FOREIGN KEY(course_id) REFERENCES courses(id)"
            ")"
        )
        cursor.execute("CREATE TABLE audit_log (event TEXT, created_at TEXT)")

        cursor.execute(
            "INSERT INTO departments (id, name) VALUES (1, 'Engineering'), (2, 'Sales')"
        )
        cursor.execute(
            "INSERT INTO employees (id, name, department_id) VALUES "
            "(1, 'Alice', 1), (2, 'Bob', 2)"
        )
        cursor.execute(
            "INSERT INTO students (id, name) VALUES (1, 'Sam'), (2, 'Riley')"
        )
        cursor.execute(
            "INSERT INTO courses (id, title) VALUES (1, 'Math'), (2, 'Science')"
        )
        cursor.execute(
            "INSERT INTO enrollments (student_id, course_id) VALUES (1, 1), (2, 2)"
        )
        cursor.execute(
            "INSERT INTO audit_log (event, created_at) "
            "VALUES ('seed', '2026-03-27T00:00:00Z')"
        )

        connection.commit()

    return str(db_path)


def test_table_schema_dataclass_fields():
    schema = TableSchema(
        name="enrollments",
        columns=["student_id", "course_id"],
        pk_columns=["student_id", "course_id"],
        fk_columns=[("student_id", "students", "id")],
    )

    assert schema.name == "enrollments"
    assert schema.columns == ["student_id", "course_id"]
    assert schema.pk_columns == ["student_id", "course_id"]
    assert schema.fk_columns == [("student_id", "students", "id")]


def test_mutation_result_dataclass_fields():
    result = MutationResult(
        mutation_name="inject_irrelevant_rows",
        tables_affected=["employees"],
        rows_added=5,
        success=True,
    )

    assert result.mutation_name == "inject_irrelevant_rows"
    assert result.tables_affected == ["employees"]
    assert result.rows_added == 5
    assert result.success is True


def test_get_table_schemas_multi_table_with_fk_and_composite_pk(sample_db_path):
    schemas = get_table_schemas(sample_db_path)
    by_name = {schema.name: schema for schema in schemas}

    assert set(by_name) == {
        "audit_log",
        "courses",
        "departments",
        "employees",
        "enrollments",
        "students",
    }
    assert by_name["departments"].pk_columns == ["id"]
    assert by_name["employees"].fk_columns == [("department_id", "departments", "id")]
    assert by_name["enrollments"].pk_columns == ["student_id", "course_id"]
    assert set(by_name["enrollments"].fk_columns) == {
        ("student_id", "students", "id"),
        ("course_id", "courses", "id"),
    }


def test_get_table_schemas_no_pk_table(sample_db_path):
    schemas = get_table_schemas(sample_db_path)
    by_name = {schema.name: schema for schema in schemas}

    assert by_name["audit_log"].pk_columns == []


def test_get_table_schemas_empty_db(tmp_path):
    db_path = tmp_path / "empty.sqlite"
    sqlite3.connect(db_path).close()

    assert get_table_schemas(str(db_path)) == []


def test_get_table_schemas_nonexistent_db_raises_operational_error(tmp_path):
    missing_path = tmp_path / "missing.sqlite"

    with pytest.raises(sqlite3.OperationalError):
        get_table_schemas(str(missing_path))


def test_detect_bridge_tables_identifies_tables_with_two_or_more_fks(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    assert detect_bridge_tables(schemas) == ["enrollments"]


def test_detect_bridge_tables_empty_when_no_bridge_tables():
    schemas = [
        TableSchema(
            name="employees",
            columns=["id", "department_id"],
            pk_columns=["id"],
            fk_columns=[("department_id", "departments", "id")],
        ),
        TableSchema(
            name="departments",
            columns=["id", "name"],
            pk_columns=["id"],
            fk_columns=[],
        ),
    ]

    assert detect_bridge_tables(schemas) == []


def test_inject_irrelevant_rows_adds_rows_with_new_primary_keys(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    result = inject_irrelevant_rows(sample_db_path, schemas, n_rows=2)

    assert result.mutation_name == "inject_irrelevant_rows"
    assert result.success is True
    assert result.rows_added == 8
    assert result.tables_affected == ["courses", "departments", "employees", "students"]

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*) FROM employees")
        assert cursor.fetchone()[0] == 4

        cursor.execute("SELECT MIN(id), MAX(id) FROM employees")
        assert cursor.fetchone() == (1, 4)


def test_inject_irrelevant_rows_preserves_existing_rows(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    inject_irrelevant_rows(sample_db_path, schemas, n_rows=1)

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT name FROM employees ORDER BY id")
        names = [row[0] for row in cursor.fetchall()]

    assert names[0:2] == ["Alice", "Bob"]


def test_inject_irrelevant_rows_zero_rows_no_change(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    result = inject_irrelevant_rows(sample_db_path, schemas, n_rows=0)

    assert result.rows_added == 0
    assert result.tables_affected == []
    assert result.success is True

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*) FROM employees")
        assert cursor.fetchone()[0] == 2


def test_remap_ids_basic_changes_integer_primary_keys(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT id FROM departments ORDER BY id")
        before_department_ids = [row[0] for row in cursor.fetchall()]

    result = remap_ids(sample_db_path, schemas)

    assert result.mutation_name == "remap_ids"
    assert result.success is True
    assert "departments" in result.tables_affected
    assert "employees" in result.tables_affected
    assert result.rows_added >= 2

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT id FROM departments ORDER BY id")
        after_department_ids = [row[0] for row in cursor.fetchall()]

    assert after_department_ids != before_department_ids
    assert len(after_department_ids) == len(before_department_ids)


def test_remap_ids_updates_foreign_keys_and_preserves_join(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    remap_ids(sample_db_path, schemas)

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()

        cursor.execute("PRAGMA foreign_key_check")
        assert cursor.fetchall() == []

        cursor.execute(
            "SELECT e.name, d.name FROM employees e "
            "JOIN departments d ON e.department_id = d.id "
            "ORDER BY e.name"
        )
        joined = cursor.fetchall()

    assert joined == [("Alice", "Engineering"), ("Bob", "Sales")]


def test_remap_ids_is_bijective_and_preserves_row_counts(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*), COUNT(DISTINCT id) FROM departments")
        before_counts = cursor.fetchone()

    remap_ids(sample_db_path, schemas)

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*), COUNT(DISTINCT id) FROM departments")
        after_counts = cursor.fetchone()

    assert after_counts == before_counts


def test_remap_ids_skips_tables_without_integer_primary_key(tmp_path):
    db_path = tmp_path / "text_pk.sqlite"
    with sqlite3.connect(db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("CREATE TABLE labels (name TEXT PRIMARY KEY, value TEXT)")
        cursor.execute("INSERT INTO labels (name, value) VALUES ('alpha', '1')")
        connection.commit()

    schemas = get_table_schemas(str(db_path))

    result = remap_ids(str(db_path), schemas)

    assert result.success is True
    assert result.rows_added == 0
    assert result.tables_affected == []


def test_duplicate_bridge_rows_adds_rows_for_bridge_tables(tmp_path):
    db_path = tmp_path / "bridge.sqlite"
    with sqlite3.connect(db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("PRAGMA foreign_keys = ON")
        cursor.execute("CREATE TABLE students (id INTEGER PRIMARY KEY, name TEXT)")
        cursor.execute("CREATE TABLE clubs (id INTEGER PRIMARY KEY, name TEXT)")
        cursor.execute(
            "CREATE TABLE club_memberships ("
            "student_id INTEGER,"
            "club_id INTEGER,"
            "FOREIGN KEY(student_id) REFERENCES students(id),"
            "FOREIGN KEY(club_id) REFERENCES clubs(id)"
            ")"
        )
        cursor.execute(
            "INSERT INTO students (id, name) VALUES (1, 'Sam'), (2, 'Riley')"
        )
        cursor.execute(
            "INSERT INTO clubs (id, name) VALUES (1, 'Chess'), (2, 'Robotics')"
        )
        cursor.execute(
            "INSERT INTO club_memberships (student_id, club_id) VALUES (1, 1), (2, 2)"
        )
        connection.commit()

    schemas = get_table_schemas(str(db_path))
    bridge_tables = detect_bridge_tables(schemas)

    result = duplicate_bridge_rows(str(db_path), schemas, bridge_tables)

    assert result.mutation_name == "duplicate_bridge_rows"
    assert result.success is True
    assert result.rows_added == 2
    assert result.tables_affected == ["club_memberships"]

    with sqlite3.connect(db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*) FROM club_memberships")
        assert cursor.fetchone()[0] == 4


def test_duplicate_bridge_rows_empty_bridge_tables_returns_noop(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    result = duplicate_bridge_rows(sample_db_path, schemas, [])

    assert result.success is True
    assert result.rows_added == 0
    assert result.tables_affected == []


def test_duplicate_bridge_rows_skips_rows_blocked_by_unique_constraints(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    result = duplicate_bridge_rows(sample_db_path, schemas, ["enrollments"])

    assert result.success is True
    assert result.rows_added == 0
    assert result.tables_affected == []

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*) FROM enrollments")
        assert cursor.fetchone()[0] == 2


def test_duplicate_bridge_rows_ignores_nonexistent_tables(sample_db_path):
    schemas = get_table_schemas(sample_db_path)

    result = duplicate_bridge_rows(sample_db_path, schemas, ["missing_bridge"])

    assert result.success is True
    assert result.rows_added == 0
    assert result.tables_affected == []


def test_validate_gold_sql_valid_returns_serialized_result(sample_db_path):
    is_valid, result = validate_gold_sql(
        sample_db_path,
        "SELECT name FROM employees ORDER BY id",
    )

    assert is_valid is True
    assert result == "[('Alice',), ('Bob',)]"


def test_validate_gold_sql_empty_result_returns_false(sample_db_path):
    is_valid, result = validate_gold_sql(
        sample_db_path,
        "SELECT name FROM employees WHERE id = -1",
    )

    assert is_valid is False
    assert result is None


def test_validate_gold_sql_invalid_query_raises_operational_error(sample_db_path):
    with pytest.raises(sqlite3.OperationalError):
        validate_gold_sql(sample_db_path, "SELECT * FROM definitely_missing_table")


def test_validate_gold_sql_honors_custom_timeout(sample_db_path):
    is_valid, result = validate_gold_sql(
        sample_db_path,
        "SELECT COUNT(*) FROM employees",
        timeout=0.001,
    )

    assert is_valid is True
    assert result == "[(2,)]"


def test_variant_result_dataclass_fields(sample_db_path):
    mutation = MutationResult(
        mutation_name="inject_irrelevant_rows",
        tables_affected=["employees"],
        rows_added=2,
        success=True,
    )
    result = VariantResult(
        variant_path="/tmp/sample_variant.sqlite",
        original_path=sample_db_path,
        mutations_applied=[mutation],
        gold_sql_valid=True,
        gold_answer="[(1,)]",
    )

    assert result.variant_path.endswith("sample_variant.sqlite")
    assert result.original_path == sample_db_path
    assert result.mutations_applied == [mutation]
    assert result.gold_sql_valid is True
    assert result.gold_answer == "[(1,)]"


def test_generate_variant_default_applies_all_mutations_and_creates_file(
    sample_db_path, tmp_path
):
    output_dir = tmp_path / "variants"

    result = generate_variant(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
    )

    assert result.gold_sql_valid is True
    assert len(result.mutations_applied) == 3
    assert [m.mutation_name for m in result.mutations_applied] == [
        "inject_irrelevant_rows",
        "remap_ids",
        "duplicate_bridge_rows",
    ]
    assert (output_dir / "sample_variant_0.sqlite").exists()


def test_generate_variant_single_mutation(sample_db_path, tmp_path):
    output_dir = tmp_path / "variants"

    result = generate_variant(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
        mutations=["inject_irrelevant_rows"],
    )

    assert result.gold_sql_valid is True
    assert [m.mutation_name for m in result.mutations_applied] == [
        "inject_irrelevant_rows"
    ]


def test_generate_variant_does_not_modify_original_db(sample_db_path, tmp_path):
    output_dir = tmp_path / "variants"

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*) FROM employees")
        before_count = cursor.fetchone()[0]

    generate_variant(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
    )

    with sqlite3.connect(sample_db_path) as connection:
        cursor = connection.cursor()
        cursor.execute("SELECT COUNT(*) FROM employees")
        after_count = cursor.fetchone()[0]

    assert before_count == after_count == 2


def test_generate_variant_raises_on_missing_db(tmp_path):
    with pytest.raises(FileNotFoundError):
        generate_variant(
            db_path=str(tmp_path / "missing.sqlite"),
            gold_sql="SELECT 1",
            output_dir=str(tmp_path / "variants"),
        )


def test_generate_variant_raises_on_unknown_mutation(sample_db_path, tmp_path):
    with pytest.raises(ValueError, match="Unknown mutation"):
        generate_variant(
            db_path=sample_db_path,
            gold_sql="SELECT name FROM employees",
            output_dir=str(tmp_path / "variants"),
            mutations=["unknown_mutation"],
        )


def test_generate_variant_invalid_gold_sql_discards_variant(sample_db_path, tmp_path):
    output_dir = tmp_path / "variants"

    result = generate_variant(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees WHERE id = 1",
        output_dir=str(output_dir),
    )

    assert result.gold_sql_valid is False
    assert result.gold_answer is None
    assert not (output_dir / "sample_variant_0.sqlite").exists()


def test_generate_variant_uses_variant_id_in_filename(sample_db_path, tmp_path):
    output_dir = tmp_path / "variants"

    result = generate_variant(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
        variant_id=7,
    )

    assert result.variant_path.endswith("sample_variant_7.sqlite")


def test_generate_variants_for_question_default_count(sample_db_path, tmp_path):
    output_dir = tmp_path / "variants"

    results = generate_variants_for_question(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
        n_variants=2,
    )

    assert len(results) == 2
    assert all(result.gold_sql_valid for result in results)


def test_generate_variants_for_question_zero_returns_empty_list(
    sample_db_path, tmp_path
):
    output_dir = tmp_path / "variants"

    results = generate_variants_for_question(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
        n_variants=0,
    )

    assert results == []


def test_generate_variants_for_question_returns_unique_paths(sample_db_path, tmp_path):
    output_dir = tmp_path / "variants"

    results = generate_variants_for_question(
        db_path=sample_db_path,
        gold_sql="SELECT name FROM employees",
        output_dir=str(output_dir),
        n_variants=3,
    )

    paths = [result.variant_path for result in results]
    assert len(paths) == len(set(paths))


def test_synthetic_cli_smoke_generates_variants(sample_db_path, tmp_path, capsys):
    output_dir = tmp_path / "variants_cli"

    exit_code = synthetic_cli_main(
        [
            "--db-path",
            sample_db_path,
            "--gold-sql",
            "SELECT name FROM employees",
            "--output-dir",
            str(output_dir),
            "--n-variants",
            "2",
        ]
    )

    captured = capsys.readouterr()
    assert exit_code == 0
    assert "Generated 2 valid variant(s)" in captured.out
    assert (output_dir / "sample_variant_0.sqlite").exists()
    assert (output_dir / "sample_variant_1.sqlite").exists()


@pytest.mark.slow
def test_generate_variants_integration_with_real_spider_database(tmp_path):
    case = _find_real_spider_case()
    if case is None:
        pytest.skip(
            "No local Spider DB + valid gold SQL pair found. "
            "Run: uv run python scripts/download_spider_databases.py"
        )

    db_path, gold_sql, db_name = case
    output_dir = tmp_path / "spider_variants" / db_name

    results = generate_variants_for_question(
        db_path=str(db_path),
        gold_sql=gold_sql,
        output_dir=str(output_dir),
        n_variants=2,
    )

    assert len(results) >= 1

    variant = results[0]
    variant_path = Path(variant.variant_path)
    assert variant_path.exists()
    assert variant.gold_sql_valid is True
    assert any(mutation.rows_added > 0 for mutation in variant.mutations_applied)

    original_schema = _sqlite_table_definitions(db_path)
    variant_schema = _sqlite_table_definitions(variant_path)
    assert variant_schema == original_schema