"""Ansible --list inventory generation from DB records."""
from __future__ import annotations
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from steward.models.ansible_inventory import AnsibleTarget


def generate_inventory(targets: list) -> dict:
    """Build an Ansible --list JSON inventory from a list of AnsibleTarget objects.

    Accepts any objects with .name, .address, .ansible_vars (dict), .groups (list
    of objects with .name and .ansible_vars). Uses duck typing so unit tests can
    pass SimpleNamespace objects.

    Var precedence (lowest → highest, matching Ansible default):
      group vars (sorted alphabetically by group name) → target ansible_vars → ansible_host
    """
    inv: dict = {"all": {"hosts": []}, "_meta": {"hostvars": {}}}

    for target in targets:
        inv["all"]["hosts"].append(target.name)

        # Merge vars: group vars alphabetically, then host vars, then force ansible_host.
        merged: dict = {}
        for group in sorted(target.groups, key=lambda g: g.name):
            merged.update(group.ansible_vars or {})
        merged.update(target.ansible_vars or {})
        merged["ansible_host"] = target.address

        inv["_meta"]["hostvars"][target.name] = merged

        for group in target.groups:
            if group.name not in inv:
                inv[group.name] = {
                    "hosts": [],
                    "vars": dict(group.ansible_vars or {}),
                }
            inv[group.name]["hosts"].append(target.name)

    return inv


async def fetch_scope_targets(db, scope: str) -> list:
    """Query AnsibleTarget objects for a given inventory scope string.

    Scopes:
      steward:all              — every target
      steward:group:<uuid>     — targets in that group
      steward:target:<uuid>    — single target by ID

    Returns a list with groups pre-loaded (selectinload). Returns [] for
    repo:* scopes (caller handles those via legacy path).
    """
    from sqlalchemy import select
    from sqlalchemy.orm import selectinload
    from steward.models.ansible_inventory import AnsibleTarget, AnsibleGroup

    if scope == "steward:all":
        stmt = (
            select(AnsibleTarget)
            .options(selectinload(AnsibleTarget.groups))
            .order_by(AnsibleTarget.name)
        )
    elif scope.startswith("steward:group:"):
        group_id = scope[len("steward:group:"):]
        stmt = (
            select(AnsibleTarget)
            .join(AnsibleTarget.groups)
            .where(AnsibleGroup.id == group_id)
            .options(selectinload(AnsibleTarget.groups))
            .order_by(AnsibleTarget.name)
        )
    elif scope.startswith("steward:target:"):
        target_id = scope[len("steward:target:"):]
        stmt = (
            select(AnsibleTarget)
            .where(AnsibleTarget.id == target_id)
            .options(selectinload(AnsibleTarget.groups))
        )
    else:
        return []

    result = await db.execute(stmt)
    return list(result.scalars().all())