import type { PartyNavigationGraph } from "./partyNavigation";
import { distanceSquared, moveMobToward, type MobAiPhase, type MobAiPosition, type MutableMobAiPosition } from "./mobAi";
import { emptyPartyRouteState, nextPartyRouteRecoveryWaypoint, nextPartyRouteWaypoint, partyRouteNeedsPlanning, planPartyRoute } from "./partyPathing";
import { createPartyStuckRecoveryState, markPartyStuckRecovered, updatePartyStuckRecovery, type PartyStuckRecoveryState } from "./partyStuckRecovery";

export const MOB_NEAR_RECOVERY_DISTANCE = 10;
const SAME_FLOOR_TOLERANCE = 1.25;

export interface MobPursuitSample {
  readonly id: string;
  readonly targetId: string | null;
  readonly position: MutableMobAiPosition;
  readonly target: MobAiPosition;
  readonly home: MobAiPosition;
  readonly phase: MobAiPhase;
  readonly health: number;
  readonly engaged: boolean;
  readonly active: boolean;
  readonly casting: boolean;
  readonly controlled: boolean;
  readonly attackRange: number;
  readonly leashRange: number;
  readonly maximumStep: number;
  readonly nowMs: number;
}

export interface MobPursuitSpatial {
  readonly graph: () => PartyNavigationGraph | null;
  readonly hasLineOfSight: (from: MobAiPosition, to: MobAiPosition) => boolean;
  readonly directAllowed: (from: MobAiPosition, to: MobAiPosition) => boolean;
  readonly routeAllowed: (from: MobAiPosition, to: MobAiPosition) => boolean;
  readonly validateLanding: (point: MobAiPosition, anchor: MobAiPosition) => MobAiPosition | null;
}

/** Never blindly land inside the target, a wall, or an overlapping dungeon floor. */
export function chooseMobPursuitLanding(sample: MobPursuitSample, spatial: MobPursuitSpatial): MobAiPosition | null {
  const { position, target, home } = sample;
  if (distanceSquared(position, target) > MOB_NEAR_RECOVERY_DISTANCE ** 2
    || Math.abs(position[1] - target[1]) > SAME_FLOOR_TOLERANCE
    || distanceSquared(home, target) > sample.leashRange ** 2) return null;
  const bearing = Math.atan2(position[0] - target[0], position[2] - target[2]);
  const radius = Math.max(0.85, Math.min(2, sample.attackRange * 0.6));
  for (let offset = 0; offset < 16; offset += 1) {
    const angle = bearing + offset * Math.PI / 8;
    const candidate: MobAiPosition = [target[0] + Math.sin(angle) * radius, target[1], target[2] + Math.cos(angle) * radius];
    const landing = spatial.validateLanding(candidate, target);
    if (landing?.every(Number.isFinite) && distanceSquared(landing, candidate) <= 0.85 ** 2
      && distanceSquared(landing, target) <= sample.attackRange ** 2
      && distanceSquared(landing, home) <= sample.leashRange ** 2
      && Math.abs(landing[1] - target[1]) <= SAME_FLOOR_TOLERANCE
      && spatial.hasLineOfSight(landing, target)) return [...landing];
  }
  return null;
}

/** Shared imperative adapter for static spawns, roaming packs, and summoned enemies. */
export function createMobPursuit(spatial: MobPursuitSpatial) {
  const states = new Map<string, {
    route: ReturnType<typeof emptyPartyRouteState>;
    watchdog: PartyStuckRecoveryState;
    graph: PartyNavigationGraph | null;
  }>();
  const desired: MutableMobAiPosition = [0, 0, 0];
  const next: MutableMobAiPosition = [0, 0, 0];
  return {
    clear: () => states.clear(),
    step(sample: MobPursuitSample): "none" | "teleported" | "reset" | "home" {
      const { position, target, home, nowMs } = sample;
      if (![...position, ...target, ...home, nowMs, sample.attackRange, sample.leashRange, sample.maximumStep].every(Number.isFinite)) return "none";
      let state = states.get(sample.id);
      if (!state) {
        state = { route: emptyPartyRouteState(), watchdog: createPartyStuckRecoveryState(position, nowMs), graph: spatial.graph() };
        states.set(sample.id, state);
      }
      const returning = sample.phase === "returning";
      const goal = returning ? home : target;
      const visible = spatial.hasLineOfSight(position, target);
      const inRange = visible && distanceSquared(position, target) <= sample.attackRange ** 2;
      const movementExpected = returning ? distanceSquared(position, home) > 0.2 ** 2 : sample.engaged && !inRange;
      const excluded = !sample.active || sample.health <= 0 || sample.controlled || sample.casting;
      const goalKey = returning ? "return-home" : `target:${sample.targetId}`;
      const graph = spatial.graph();
      if (state.graph !== graph) {
        state.graph = graph;
        state.route = emptyPartyRouteState();
      }
      let waypoint: MobAiPosition | null = null;
      let approvedRouteStep = false;
      if (movementExpected && !excluded) {
        if (spatial.directAllowed(position, goal)) waypoint = goal;
        else {
          if (partyRouteNeedsPlanning(state.route, goalKey, position, goal, nowMs, { replanIntervalMs: 350, blockedRetryMs: 800 })) {
            state.route = planPartyRoute(graph, goalKey, position, goal, nowMs, {
              maxOriginSnapDistance: 3, maxDestinationSnapDistance: 3,
              directSegmentAllowed: spatial.directAllowed,
              routeSegmentAllowed: graph?.triangles?.length || graph?.detourSurface
                ? spatial.routeAllowed
                : undefined,
              destinationReached: (surface, destination) => distanceSquared(surface, destination)
                <= (returning ? 0.2 : sample.attackRange) ** 2
                && (returning || spatial.hasLineOfSight(surface, destination)),
            });
          }
          if (nextPartyRouteWaypoint(state.route, position, desired)) {
            waypoint = desired;
            approvedRouteStep = true;
          } else if (nextPartyRouteRecoveryWaypoint(state.route, position, desired, spatial.directAllowed)) waypoint = desired;
        }
        if (waypoint) {
          moveMobToward(position, waypoint, sample.maximumStep, next);
          // Recast edges are already agent-radius eroded. A second full-radius
          // sweep at boundary vertices can reject a valid stair corridor;
          // use the same center/wall check as companions on approved edges.
          // Off-surface connectors and direct shortcuts still need body sweeps.
          if (spatial.directAllowed(position, next) || (approvedRouteStep && spatial.routeAllowed(position, next))) {
            position[0] = next[0]; position[1] = next[1]; position[2] = next[2];
          }
        }
      }
      const recovery = updatePartyStuckRecovery(state.watchdog, {
        position, waypoint, goalKey, movementExpected, nowMs, health: sample.health,
        paused: !sample.active, stopped: false, casting: sample.casting, controlled: sample.controlled,
      });
      if (returning && !excluded && !movementExpected) return "home";
      if (recovery !== "none") state.route = emptyPartyRouteState();
      if (recovery !== "recover") return "none";
      const landing = returning ? spatial.validateLanding(home, home) : chooseMobPursuitLanding(sample, spatial);
      if (landing && (!returning || distanceSquared(landing, home) <= 0.85 ** 2)) {
        position[0] = landing[0]; position[1] = landing[1]; position[2] = landing[2];
        markPartyStuckRecovered(state.watchdog, position, nowMs);
        return returning ? "home" : "teleported";
      }
      if (!returning) {
        const homeLanding = spatial.validateLanding(home, home);
        if (homeLanding?.every(Number.isFinite) && distanceSquared(homeLanding, home) <= 0.85 ** 2) {
          position[0] = homeLanding[0]; position[1] = homeLanding[1]; position[2] = homeLanding[2];
        }
        markPartyStuckRecovered(state.watchdog, position, nowMs);
        return "reset";
      }
      return "none";
    },
  };
}