# scopes.core.core

"""A concurrent cybernetic communication system"""

from __future__ import annotations  # no check of type annotations at runtime
import asyncio
from collections.abc import Awaitable, Callable, Coroutine
from dataclasses import dataclass, field
from typing import Any, Self

from scopes.core import actor
from scopes.core.message import Message
from scopes import util
from scopes.util import keywords as k, Symbol

type Mailbox = asyncio.Queue
type Categ = tuple[Symbol, Symbol]
type Proc = Callable[[Message, Scope], Awaitable[Scope | None]]
type Program = Callable[[Scope], Proc]
type ProgramSpec = dict[tuple[Symbol, Symbol], Proc]
type Syn = Callable[[Message], Awaitable[None]]
type SynOp = Callable[[Message], Message | None]

type Handler = Callable[[Message, Scope], 
     Awaitable[Message | None | tuple[Message | None, Scope | None]]]
type Handlers = Handler | None | list[Handlers]
type Actions = dict[Symbol, Handlers]

env_dummy: Mailbox = asyncio.Queue()

def notify() -> Handler:
    async def handle(msg, scope) -> None:
        await scope.environ.put(msg)
    return handle

def gen_proc(actions: Actions, default: Handlers = notify(),
             prepare: Handlers = None, finalize: Handlers = None) -> Proc:
    async def proc(msg: Message, scope: Scope) -> Scope:
        acts = actions.get(msg.head['action'], actions.get(k.default, default))
        acts = util.flatten(prepare, acts, finalize, ignore_none=True)
        for act in acts:
            msg = await act(msg, scope)
            if isinstance(msg, tuple):
                msg, new_scope = msg
                if new_scope is not None:
                    scope = new_scope
            if msg is None:
                break
        return scope
    return proc

def gen_program(spec: ProgramSpec, default: Proc = gen_proc({})) -> Program:
    def program(scope: Scope) -> Proc:
        key = (scope.categ[1], scope.stage)
        proc = spec.get(key, spec.get((key[0], k.default)))
        if proc is None:
            proc = spec.get((k.default, key[1]), default)
        return proc
    return program

@dataclass
class Scope:

    value: Any = 0
    categ: Categ = (k.csys, k.c00)
    stage: Symbol = k.initial
    proc: Proc = field(init=False)
    program: Program = gen_program({})
    syns: list[Syn] = field(default_factory=list)
    environ: Mailbox = env_dummy

    def __post_init__(self):
        self.set_proc()

    def set_proc(self) -> Self:
        self.proc = self.program(self)
        return self

def create_scope(env: Mailbox, cat: Categ = (k.csys, k.c00), **kw) -> Scope:
    return Scope(environ=env, categ=cat, **kw)

def neuron(scope: Scope) -> Mailbox:
    async def process(msg: Message) -> actor.Behavior | None:
        nonlocal scope
        scope = await scope.proc(msg, scope) or scope
        return process
    return actor.create(process)

def create_zero(env: Mailbox) -> Mailbox:
    scope = create_scope(env)
    zero = neuron(scope)
    return zero

def synapse(rcvr: Mailbox, op: SynOp = lambda x: x) -> Syn:
    async def syn(msg: Message) -> None:
        # op = update_op(msg) (=> return?)
        # rv = check_return(msg) => return rv
        msg_new = op(msg)
        if msg_new is not None:
            await rcvr.put(msg_new)
    return syn

def std_proc(actions: Actions) -> Proc:
    return gen_proc(actions, finalize=forward())

def basic_actions() -> Actions:
    acts: Actions = {
        k.value: value_add(),
        k.create: create()
    }
    return acts

# predefined action handlers

def forward() -> Handler:
    async def handle(msg, scope) -> None:
        for syn in scope.syns:
            await syn(msg)
    return handle

def value_add() -> Handler:
    async def handle(msg, scope) -> tuple[Message, Scope]:
        return msg, scope
    return handle

def create() -> Handler:
    async def handle(msg, scope) -> None:
        return None
    return handle