"""
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

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?",
})


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

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
# ---------------------------------------------------------------------------

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 = {k: v for k, v in kwargs.items() if v is not None}

    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 = {k: v for k, v in kwargs.items() if v is not None}

    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 = {k: v for k, v in kwargs.items() if v is not None}

    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


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

_IO_HANDLERS: dict[str, Any] = {
    "frag": _io_frag,
    "query": _io_query,
    "action": _io_action,
    "current-user": _io_current_user,
    "htmx-request?": _io_htmx_request,
}