"""Deterministic autopilot for social (non-survival) worlds.

The autopilot fills gaps: it produces one safe, goal-consistent primitive when
an NPC has no usable directive (LLM error, unknown action, omitted NPC). It is
a fallback, never a filter — it does not constrain what a planner may choose.
"""

from __future__ import annotations

from world_simulator.domain import CitizenGoal, Npc, WorldState
from world_simulator.simulation.connectors.base import NpcDirective
from world_simulator.simulation.mechanics import (
    ATTACK_RADIUS,
    distance_between,
    is_alive,
    walk_away_target,
)
from world_simulator.simulation.perception import CitizenPerception, nearby_threat_npc


def autopilot_directive(
    world: WorldState,
    npc: Npc,
    directive: NpcDirective,
    perception: CitizenPerception,
    goal: CitizenGoal | None,
) -> NpcDirective:
    target = target_from_directive_or_goal(world, npc, directive, goal, perception)

    if (
        goal is not None
        and goal.goal_type in ("pursue_and_attack_target", "retaliate")
        and target is not None
    ):
        return strike_or_approach_target(
            npc,
            directive,
            target,
            memory="Autopilot pursued the hostile target.",
        )

    if goal is not None and goal.goal_type in ("survive", "call_for_help", "help_or_defend"):
        if goal.goal_type == "call_for_help":
            return NpcDirective(
                npc_id=npc.id,
                action="speak",
                message="Help! I am in danger!",
                memory="Autopilot called for help.",
                communication_intent="help_request",
                intent="call_for_help",
            )
        if target is not None:
            return flee_directive(world, npc, target, directive)
        return idle_directive(
            directive,
            memory="Autopilot held a defensive stance.",
            intent="defend",
        )

    if (
        goal is not None
        and goal.goal_type in ("respond_to_event", "investigate")
        and target is not None
    ):
        return move_toward_target_directive(npc, directive, target, intent="investigate")

    return idle_directive(directive, memory=None, intent="observe")


def target_from_directive_or_goal(
    world: WorldState,
    npc: Npc,
    directive: NpcDirective,
    goal: CitizenGoal | None,
    perception: CitizenPerception,
) -> Npc | None:
    if directive.target_npc_id:
        target = _npc_by_id(world, directive.target_npc_id)
        if target is not None and target.id != npc.id and is_alive(target):
            return target

    if goal is not None and goal.target_npc_id:
        target = _npc_by_id(world, goal.target_npc_id)
        if target is not None and target.id != npc.id and is_alive(target):
            return target

    threat = nearby_threat_npc(world, perception)
    if threat is not None and threat.id != npc.id and is_alive(threat):
        return threat

    return None


def strike_or_approach_target(
    npc: Npc,
    directive: NpcDirective,
    target: Npc,
    *,
    memory: str,
) -> NpcDirective:
    if distance_between(npc, target) <= ATTACK_RADIUS:
        return NpcDirective(
            npc_id=npc.id,
            action="attack",
            target_npc_id=target.id,
            message=directive.message,
            memory=memory,
            intent="hostile_attack",
            confidence=directive.confidence,
        )
    return move_toward_target_directive(
        npc,
        directive,
        target,
        intent="approach_target_for_attack",
        memory=memory,
    )


def move_toward_target_directive(
    npc: Npc,
    directive: NpcDirective,
    target: Npc,
    *,
    intent: str,
    memory: str | None = None,
) -> NpcDirective:
    return NpcDirective(
        npc_id=npc.id,
        action="move",
        target=target.position,
        target_npc_id=target.id,
        message=directive.message,
        memory=memory or f"You moved toward {target.name}.",
        intent=intent,
        confidence=directive.confidence,
    )


def flee_directive(
    world: WorldState,
    npc: Npc,
    threat: Npc,
    directive: NpcDirective,
) -> NpcDirective:
    half_width = world.terrain.width / 2
    half_depth = world.terrain.depth / 2
    return NpcDirective(
        npc_id=npc.id,
        action="move",
        target=walk_away_target(npc, threat, half_width=half_width, half_depth=half_depth),
        target_npc_id=threat.id,
        message=directive.message,
        memory=f"You backed away from {threat.name}.",
        intent="flee_from_threat",
        confidence=directive.confidence,
    )


def idle_directive(
    directive: NpcDirective,
    *,
    memory: str | None,
    intent: str,
) -> NpcDirective:
    return NpcDirective(
        npc_id=directive.npc_id,
        action="idle",
        target=None,
        target_npc_id=directive.target_npc_id,
        message=directive.message,
        memory=memory,
        intent=intent,
        confidence=directive.confidence,
    )


def _npc_by_id(world: WorldState, npc_id: str) -> Npc | None:
    return next((candidate for candidate in world.living_npcs() if candidate.id == npc_id), None)