#!/usr/bin/env python3
"""Pre-commit hook: ensure DateTime columns in models and migrations use UtcDateTime.

Scans files under ``src/local_deep_research/database/models/`` and
``src/local_deep_research/database/migrations/versions/`` for
``Column(...)`` / ``sa.Column(...)`` calls whose type argument is a bare
``DateTime`` (with or without ``timezone=True``). Flags them and hints at
the ``UtcDateTime`` replacement from ``sqlalchemy_utc``.

Limitations (accepted gaps, not caught by this hook):
- Raw SQL inside ``op.execute("... DATETIME ...")`` — the hook cannot
  parse SQL strings.
- Type-alias indirection: ``dt = sa.DateTime(); sa.Column("x", dt)``.
- Fully-qualified imports without the ``sa`` alias
  (e.g. ``import sqlalchemy; sqlalchemy.Column(...)``).
- ``sa.TIMESTAMP`` columns.
- Walrus expressions: ``Column((dt := DateTime()))`` wraps the call in
  ``ast.NamedExpr``, which the helper does not traverse.
- Import-order variations beyond the two hardcoded substring forms.
"""

import ast
import re
import sys
from pathlib import Path
from typing import List, Tuple


def _callable_name(func_node):
    """Return the callable's short name regardless of ``X`` or ``sa.X`` form."""
    if isinstance(func_node, ast.Name):
        return func_node.id
    if isinstance(func_node, ast.Attribute):
        return func_node.attr
    return None


def _resolve_type_arg(arg):
    """Return list of ('call', Call) or ('name', str) entries for all
    type-like nodes in arg's subtree. Returns [] when arg is not a type
    reference.

    For ast.IfExp, BOTH branches are included — returning only the
    first-resolved branch would silently pass a violation that lives
    in the other branch.
    """
    if isinstance(arg, ast.Call):
        return [("call", arg)]
    if isinstance(arg, ast.Name) and arg.id in {"UtcDateTime", "DateTime"}:
        return [("name", arg.id)]
    if isinstance(arg, ast.IfExp):
        return _resolve_type_arg(arg.body) + _resolve_type_arg(arg.orelse)
    return []


def check_datetime_columns(file_path: Path) -> List[Tuple[int, str, str]]:
    """Check a Python file for DateTime columns that should use UtcDateTime.

    Returns a list of (line_number, line_content, error_message) tuples for violations.
    """
    violations = []

    try:
        with open(file_path, "r", encoding="utf-8") as f:
            content = f.read()
            lines = content.split("\n")
    except Exception as e:
        print(f"Error reading {file_path}: {e}", file=sys.stderr)
        return violations

    has_utc_datetime_import = (
        "from sqlalchemy_utc import UtcDateTime" in content
        or "from sqlalchemy_utc import utcnow, UtcDateTime" in content
    )

    try:
        tree = ast.parse(content)
    except SyntaxError:
        return violations

    fix_hint = (
        "Use UtcDateTime() instead of DateTime() — "
        "import: from sqlalchemy_utc import UtcDateTime"
    )

    for node in ast.walk(tree):
        if not isinstance(node, ast.Call):
            continue
        if _callable_name(node.func) != "Column":
            continue

        type_entries = []
        for arg in node.args:
            type_entries = _resolve_type_arg(arg)
            if type_entries:
                break

        for kind, payload in type_entries:
            if kind == "call":
                inner_name = _callable_name(payload.func)
                if inner_name == "DateTime":
                    line_num = node.lineno
                    if 0 <= line_num - 1 < len(lines):
                        violations.append(
                            (line_num, lines[line_num - 1].strip(), fix_hint)
                        )
                elif inner_name == "UtcDateTime":
                    if not has_utc_datetime_import:
                        line_num = node.lineno
                        if 0 <= line_num - 1 < len(lines):
                            violations.append(
                                (
                                    line_num,
                                    lines[line_num - 1].strip(),
                                    "Missing import: from sqlalchemy_utc import UtcDateTime",
                                )
                            )
            elif kind == "name":
                if payload == "DateTime":
                    line_num = node.lineno
                    if 0 <= line_num - 1 < len(lines):
                        violations.append(
                            (line_num, lines[line_num - 1].strip(), fix_hint)
                        )
                elif payload == "UtcDateTime" and not has_utc_datetime_import:
                    line_num = node.lineno
                    if 0 <= line_num - 1 < len(lines):
                        violations.append(
                            (
                                line_num,
                                lines[line_num - 1].strip(),
                                "Missing import: from sqlalchemy_utc import UtcDateTime",
                            )
                        )

    for i, line in enumerate(lines, 1):
        if "func.now()" in line and "Column" in line:
            violations.append(
                (
                    i,
                    line.strip(),
                    "Use utcnow() instead of func.now() for timezone-aware defaults",
                )
            )
        if re.search(
            r"default\s*=\s*(lambda:\s*)?datetime\.(utcnow|now)", line
        ):
            violations.append(
                (
                    i,
                    line.strip(),
                    "Use utcnow() from sqlalchemy_utc instead of datetime functions for defaults",
                )
            )

    return violations


def main():
    """Main entry point for the pre-commit hook."""
    files_to_check = sys.argv[1:]

    if not files_to_check:
        print("No files to check")
        return 0

    all_violations = []

    for file_path_str in files_to_check:
        file_path = Path(file_path_str)

        path_str = str(file_path)
        in_scope = file_path.suffix == ".py" and (
            "src/local_deep_research/database/models/" in path_str
            or "src/local_deep_research/database/migrations/versions/"
            in path_str
        )
        if not in_scope:
            continue

        violations = check_datetime_columns(file_path)
        if violations:
            all_violations.append((file_path, violations))

    if all_violations:
        print("\nDateTime column issues found:\n")
        for file_path, violations in all_violations:
            print(f"  {file_path}:")
            for line_num, line_content, error_msg in violations:
                print(f"    Line {line_num}: {error_msg}")
                print(f"      > {line_content}")
        print(
            "\n  Fix: use UtcDateTime from sqlalchemy_utc for all datetime columns"
        )
        print(
            "  (applies to both database/models/ and database/migrations/versions/)"
        )
        print("  Example: ")
        print("    from sqlalchemy_utc import UtcDateTime, utcnow")
        print("    Column(UtcDateTime, default=utcnow(), ...)\n")
        return 1

    return 0


if __name__ == "__main__":
    sys.exit(main())