"""
Async I/O primitives for the s-expression resolver.

These wrap rose-ash's inter-service communication layer so that s-expressions
can fetch fragments, query data, call actions, and access request context.

Unlike pure primitives (primitives.py), these are **async** and are executed
by the resolver rather than the evaluator.  They are identified by name
during the tree-walk phase and dispatched via ``asyncio.gather()``.

Usage in s-expressions::

    (frag "blog" "link-card" :slug "apple")
    (query "market" "products-by-ids" :ids "1,2,3")
    (action "market" "create-marketplace" :name "Farm Shop" :slug "farm")
    (current-user)
    (htmx-request?)
"""

from __future__ import annotations

import contextvars
from typing import Any

# ---------------------------------------------------------------------------
# Registry of async primitives (name → metadata)
# ---------------------------------------------------------------------------

# Names that the resolver recognises as I/O nodes requiring async resolution.
# The resolver collects these during tree-walk, groups them, and dispatches
# them in parallel.
IO_PRIMITIVES: frozenset[str] = frozenset({
    "frag",
    "query",
    "action",
    "current-user",
    "htmx-request?",
    "service",
    "request-arg",
    "request-path",
    "nav-tree",
    "get-children",
    "g",
})


# ---------------------------------------------------------------------------
# Request context  (set per-request by the resolver)
# ---------------------------------------------------------------------------

# ContextVar for the handler's domain service object.
# Set by the handler blueprint before executing a defhandler.
_handler_service: contextvars.ContextVar[Any] = contextvars.ContextVar(
    "_handler_service", default=None
)


def set_handler_service(service_obj: Any) -> None:
    """Bind the local domain service for ``(service ...)`` primitive calls."""
    _handler_service.set(service_obj)


def get_handler_service() -> Any:
    """Get the currently bound handler service, or None."""
    return _handler_service.get(None)


class RequestContext:
    """Per-request context provided to I/O primitives.

    Populated by the resolver from the Quart request before resolution begins.
    """
    __slots__ = ("user", "is_htmx", "extras")

    def __init__(
        self,
        user: dict[str, Any] | None = None,
        is_htmx: bool = False,
        extras: dict[str, Any] | None = None,
    ):
        self.user = user
        self.is_htmx = is_htmx
        self.extras = extras or {}


# ---------------------------------------------------------------------------
# I/O dispatch
# ---------------------------------------------------------------------------

async def execute_io(
    name: str,
    args: list[Any],
    kwargs: dict[str, Any],
    ctx: RequestContext,
) -> Any:
    """Execute an I/O primitive by name.

    Called by the resolver after collecting and grouping I/O nodes.
    Returns the result to be substituted back into the tree.
    """
    handler = _IO_HANDLERS.get(name)
    if handler is None:
        raise RuntimeError(f"Unknown I/O primitive: {name}")
    return await handler(args, kwargs, ctx)


# ---------------------------------------------------------------------------
# Individual handlers
# ---------------------------------------------------------------------------

def _clean_kwargs(kwargs: dict[str, Any]) -> dict[str, Any]:
    """Strip None and NIL values from kwargs for Python interop."""
    from .types import NIL
    return {k: v for k, v in kwargs.items() if v is not None and v is not NIL}


async def _io_frag(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> str:
    """``(frag "service" "type" :key val ...)`` → fetch_fragment."""
    if len(args) < 2:
        raise ValueError("frag requires service and fragment type")
    service = str(args[0])
    frag_type = str(args[1])
    params = _clean_kwargs(kwargs)

    from shared.infrastructure.fragments import fetch_fragment
    return await fetch_fragment(service, frag_type, params=params or None)


async def _io_query(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> Any:
    """``(query "service" "query-name" :key val ...)`` → fetch_data."""
    if len(args) < 2:
        raise ValueError("query requires service and query name")
    service = str(args[0])
    query_name = str(args[1])
    params = _clean_kwargs(kwargs)

    from shared.infrastructure.data_client import fetch_data
    return await fetch_data(service, query_name, params=params or None)


async def _io_action(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> Any:
    """``(action "service" "action-name" :key val ...)`` → call_action."""
    if len(args) < 2:
        raise ValueError("action requires service and action name")
    service = str(args[0])
    action_name = str(args[1])
    payload = _clean_kwargs(kwargs)

    from shared.infrastructure.actions import call_action
    return await call_action(service, action_name, payload=payload or None)


async def _io_current_user(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> dict[str, Any] | None:
    """``(current-user)`` → user dict from request context."""
    return ctx.user


async def _io_htmx_request(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> bool:
    """``(htmx-request?)`` → True if HX-Request header present."""
    return ctx.is_htmx


async def _io_service(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> Any:
    """``(service "svc-name" "method-name" :key val ...)`` → call domain service.

    Looks up the service from the shared registry by name, then calls the
    named method with ``g.s`` (async session) + keyword args.  Falls back
    to the bound handler service if only one positional arg is given.
    """
    if not args:
        raise ValueError("service requires at least a method name")

    if len(args) >= 2:
        # (service "calendar" "associated-entries" :key val ...)
        from shared.services.registry import services as svc_registry
        svc_name = str(args[0]).replace("-", "_")
        svc = getattr(svc_registry, svc_name, None)
        if svc is None:
            raise RuntimeError(f"No service registered as: {svc_name}")
        method_name = str(args[1]).replace("-", "_")
    else:
        # (service "method-name" :key val ...) — legacy / bound service
        svc = get_handler_service()
        if svc is None:
            raise RuntimeError(
                "No handler service bound — cannot call (service ...)")
        method_name = str(args[0]).replace("-", "_")

    method = getattr(svc, method_name, None)
    if method is None:
        raise RuntimeError(f"Service has no method: {method_name}")

    # Convert kwarg keys from kebab-case to snake_case, NIL → None
    from .types import NIL
    clean_kwargs = {
        k.replace("-", "_"): (None if v is NIL else v)
        for k, v in kwargs.items()
    }
    from quart import g
    result = await method(g.s, **clean_kwargs)

    return _convert_result(result)


def _dto_to_dict(obj: Any) -> dict[str, Any]:
    """Convert a DTO/dataclass/namedtuple to a plain dict.

    Adds ``{field}_year``, ``{field}_month``, ``{field}_day`` convenience
    keys for any datetime-valued field so sx handlers can build URL paths
    without parsing date strings.
    """
    if hasattr(obj, "_asdict"):
        d = dict(obj._asdict())
    elif hasattr(obj, "__dict__"):
        d = {k: v for k, v in obj.__dict__.items() if not k.startswith("_")}
    else:
        return {"value": obj}
    # Expand datetime fields into year/month/day convenience keys
    for key, val in list(d.items()):
        if hasattr(val, "year") and hasattr(val, "strftime"):
            d[f"{key}_year"] = val.year
            d[f"{key}_month"] = val.month
            d[f"{key}_day"] = val.day
    return d


def _convert_result(result: Any) -> Any:
    """Convert a service method result for sx consumption."""
    if result is None:
        from .types import NIL
        return NIL
    if isinstance(result, tuple):
        # Tuple returns (e.g. (entries, has_more)) → list for sx access
        return [_convert_result(item) for item in result]
    if hasattr(result, "__dataclass_fields__") or hasattr(result, "_asdict"):
        return _dto_to_dict(result)
    if isinstance(result, list):
        return [
            _dto_to_dict(item)
            if hasattr(item, "__dataclass_fields__") or hasattr(item, "_asdict")
            else item
            for item in result
        ]
    return result


async def _io_request_arg(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> Any:
    """``(request-arg "name" default?)`` → request.args.get(name, default)."""
    if not args:
        raise ValueError("request-arg requires a name")
    from quart import request
    name = str(args[0])
    default = args[1] if len(args) > 1 else None
    return request.args.get(name, default)


async def _io_request_path(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> str:
    """``(request-path)`` → request.path."""
    from quart import request
    return request.path


async def _io_nav_tree(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> list[dict[str, Any]]:
    """``(nav-tree)`` → list of navigation menu node dicts."""
    from quart import g
    from shared.services.navigation import get_navigation_tree
    nodes = await get_navigation_tree(g.s)
    return [_dto_to_dict(node) for node in nodes]


async def _io_get_children(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> list[dict[str, Any]]:
    """``(get-children :parent-type "page" :parent-id 1 ...)``"""
    from quart import g
    from shared.services.relationships import get_children
    clean = {k.replace("-", "_"): v for k, v in kwargs.items()}
    children = await get_children(g.s, **clean)
    return [_dto_to_dict(child) for child in children]


# ---------------------------------------------------------------------------
# Handler registry
# ---------------------------------------------------------------------------

async def _io_g(
    args: list[Any], kwargs: dict[str, Any], ctx: RequestContext
) -> Any:
    """``(g "key")`` → getattr(g, key, None).

    Reads a value from the Quart request-local ``g`` object.
    Kebab-case keys are converted to snake_case automatically.
    """
    from quart import g
    key = str(args[0]).replace("-", "_") if args else ""
    return getattr(g, key, None)


_IO_HANDLERS: dict[str, Any] = {
    "frag": _io_frag,
    "query": _io_query,
    "action": _io_action,
    "current-user": _io_current_user,
    "htmx-request?": _io_htmx_request,
    "service": _io_service,
    "request-arg": _io_request_arg,
    "request-path": _io_request_path,
    "nav-tree": _io_nav_tree,
    "get-children": _io_get_children,
    "g": _io_g,
}
