import { ordinaryLeaderSkillModeSupported } from './leader-skill-profile';
import type { Action, Game, GameView } from './engine';
import { GRAPH, location, mobileRouteDistance, splitLocation, MOBILE_LOCATION, validGameLocation } from './board';
import { isAdvisor } from './advisors';
import { strongholdPathBlocked } from './occupancy';
import { botMovementRange } from './bot-mobility';
import { planetologistFlightSelection as movementFlightSelection } from './planetologist-flight';
import { validateCohortSelection, type MovementMarker, type OrnithopterMode } from './ornithopter';
import { isBoardNoFieldLocation } from './richese-no-field';

export class SandmasterMovementError extends Error {}
export type SandmasterChoice = {
  routes: Record<string, string[]>;
  collect: string[];
};
export type SandmasterOrder = {
  group: [string, number][];
  eliteGroup: Record<string, number>;
  elite: number;
  origin: string;
  to: string;
  sector: number;
  range: number;
  noField?: MovementMarker;
  flight?: SandmasterFlight;
};
export type SandmasterFlight =
  | { kind: 'physical'; card: string; mode: OrnithopterMode; completed: number; event?: string }
  | { kind: 'discovery'; token: string; acquiredTurn: number };

/** A marker and physical counters in the same sector share one declared route. */
export function sandmasterOrderSources(order: SandmasterOrder): string[] {
  return [...new Set([...order.group.map(([key]) => key), ...(order.noField ? [order.noField.from] : [])])];
}
export type SandmasterMovement = SandmasterChoice & {
  leader: string;
  turn: number;
  move: number;
  order: string;
  piles: { key: string; before: number }[];
};
function requireMove(ok: unknown, message: string): asserts ok {
  if (!ok) throw new SandmasterMovementError(message);
}
const record = (value: unknown): value is Record<string, unknown> =>
  !!value && typeof value === 'object' && !Array.isArray(value);

export function sandmasterModeSupported(g: Game | GameView): boolean {
  return ordinaryLeaderSkillModeSupported(g);
}
export function sandmasterLeader(
  g: Game | GameView,
  player: string,
): string | null {
  const skill = g.leaderSkills?.assignments.find(
    (a) => a.owner === player && a.skill === 'sandmaster',
  );
  if (
    !skill ||
    ('controller' in skill && skill.controller !== player) ||
    ('faceUp' in skill && !skill.faceUp)
  )
    return null;
  const leader = g.players
    .find((p) => p.id === player)
    ?.leaders.find((l) => l.id === skill.leader);
  return leader && !leader.dead && !leader.capturedBy && !leader.gholaBy
    ? leader.id
    : null;
}

export type SandmasterDestinationCollection = {
  leader: string;
  key: string | null;
  before: number;
  piles: { key: string; before: number }[];
  blocked: string | null;
};

/** Direct relocation enters only its destination, never an invented route. */
export function sandmasterDestinationCollection(
  game: Game | GameView,
  player: string,
  origin: string,
  destination: string,
  sector: number,
  selectedPile?: string,
): SandmasterDestinationCollection | null {
  const leader = sandmasterLeader(game, player);
  if (!leader) return null;
  const blocked = (reason: string): SandmasterDestinationCollection =>
    ({ leader, key: null, before: 0, piles: [], blocked: reason });
  if (!sandmasterModeSupported(game))
    return blocked('Sandmaster collection with this configuration is still being integrated.');
  if (origin === destination || !validGameLocation(game, destination, sector) ||
      sector === game.storm)
    return blocked('Choose a different legal destination territory for Sandmaster collection.');
  const piles: { key: string; before: number }[] = [];
  for (const pile in game.spice) {
    const at = splitLocation(pile);
    if (at.territory !== destination) continue;
    const amount = game.spice[pile];
    if (!validGameLocation(game, at.territory, at.sector) ||
        pile !== location(at.territory, at.sector) ||
        !Number.isSafeInteger(amount) || amount < 0)
      return blocked('Sandmaster needs a valid destination spice pile.');
    if (!amount) continue;
    piles.push({ key: pile, before: amount });
  }
  if (!piles.length) return blocked('There is no spice to collect at this destination.');
  piles.sort((a, b) => a.key.localeCompare(b.key));
  const chosen = selectedPile === undefined ? piles[0] : piles.find(pile => pile.key === selectedPile);
  if (!chosen) return blocked('Choose an existing positive spice pile at this destination.');
  const spice = game.players.find(p => p.id === player)?.spice;
  if (!Number.isSafeInteger(spice) || !Number.isSafeInteger(spice! + 1))
    return blocked('Sandmaster collection needs a valid spice balance.');
  return { leader, key: chosen.key, before: chosen.before, piles, blocked: null };
}

export function sandmasterPathBlocked(
  g: Game | GameView,
  player: string,
  from: string,
  key: string,
): boolean {
  const p = g.players.find((p) => p.id === player);
  const pointer = g.mobileStronghold?.location;
  if (!p || (!Object.hasOwn(GRAPH, key) && key !== MOBILE_LOCATION)) return true;
  if (key === MOBILE_LOCATION && (!pointer || !Object.hasOwn(GRAPH, pointer) ||
    (!!splitLocation(pointer).sector && splitLocation(pointer).sector === g.storm))) return true;
  const at = splitLocation(key);
  return (
    (!!at.sector && at.sector === g.storm) ||
    strongholdPathBlocked(
      g.players,
      player,
      at.territory,
      isAdvisor(p, splitLocation(from).territory),
    )
  );
}

/** The HMS interior is a room-local dead end connected only through its pointer. */
export function sandmasterAdjacent(g: Game | GameView, key: string): string[] {
  const pointer = g.mobileStronghold?.location;
  if (key === MOBILE_LOCATION) return pointer && Object.hasOwn(GRAPH, pointer) ? [pointer] : [];
  return [...(GRAPH[key] ?? []), ...(pointer === key ? [MOBILE_LOCATION] : [])];
}

/** Ordinary forces may enter or leave HMS; this never relocates its pointer. */
export function sandmasterRouteDistance(g: Game | GameView, route: string[]): number {
  if (!route.includes(MOBILE_LOCATION)) return mobileRouteDistance(route);
  if (!route.length || route.length > Object.keys(GRAPH).length + 1 ||
    new Set(route).size !== route.length || route.slice(1, -1).includes(MOBILE_LOCATION)) return Infinity;
  let steps = 0;
  for (let index = 0; index < route.length; index++) {
    const key = route[index];
    if (key !== MOBILE_LOCATION && !Object.hasOwn(GRAPH, key)) return Infinity;
    if (key === MOBILE_LOCATION && !sandmasterAdjacent(g, key).length) return Infinity;
    if (!index) continue;
    if (!sandmasterAdjacent(g, route[index - 1]).includes(key)) return Infinity;
    steps += Number(splitLocation(route[index - 1]).territory !== splitLocation(key).territory);
  }
  return steps;
}
/** Only crossing a territory boundary enters a new collection opportunity. */
export function sandmasterEnteredTerritories(
  routes: Record<string, string[]>,
): string[] {
  return [
    ...new Set(
      Object.values(routes).flatMap((route) =>
        route.slice(1).flatMap((key, i) => {
          const id = splitLocation(key).territory;
          return id !== splitLocation(route[i]).territory ? [id] : [];
        }),
      ),
    ),
  ];
}
/** Optional collection chooses at most one existing pile in each entered territory. */
export function sandmasterCollectionPiles(
  g: Game | GameView,
  routes: Record<string, string[]>,
): Record<string, string[]> {
  const choices: Record<string, string[]> = {};
  const keys = Object.keys(g.spice);
  for (const id of sandmasterEnteredTerritories(routes)) {
    const piles = keys.filter(key => splitLocation(key).territory === id && g.spice[key] > 0).sort();
    if (piles.length) choices[id] = piles;
  }
  return choices;
}

export function quoteSandmasterStronghold(game: Game | GameView, player: string, route: string[]) {
  const seat = game.players.find(p => p.id === player);
  const leader = sandmasterLeader(game, player);
  if (!leader || !sandmasterModeSupported(game) || seat?.faction !== 'ixians' ||
      !(seat.forces[MOBILE_LOCATION] > 0)) return null;
  const piles = sandmasterCollectionPiles(game, { interior: route });
  return { leader, piles, collect: Object.values(piles).map(keys => keys[0]) };
}

/** Native collection remains separate; this selects only the skill's one spice per territory. */
export function validateSandmasterStronghold(
  game: Game | GameView, player: string, route: string[], selection: unknown, enabled = true,
): string[] {
  if (!enabled) {
    requireMove(selection === undefined || (Array.isArray(selection) && selection.length === 0),
      'Declining stronghold collection cannot take Sandmaster spice.');
    return [];
  }
  const quote = quoteSandmasterStronghold(game, player, route);
  if (selection === undefined) {
    requireMove(!quote || Object.values(quote.piles).every(keys => keys.length === 1),
      'Choose the Sandmaster debit pile for each entered territory, or decline its collection.');
    return quote?.collect ?? [];
  }
  requireMove(Array.isArray(selection) && selection.every(key => typeof key === 'string'),
    'Choose Sandmaster pile keys for this stronghold route.');
  requireMove(selection.length === 0 || !!quote,
    'Stronghold Sandmaster collection needs its living native trainer and passengers.');
  requireMove(selection.every(key => quote?.piles[splitLocation(key).territory]?.includes(key) &&
      Number.isSafeInteger(game.spice[key]) && game.spice[key] > 0) &&
    new Set(selection.map(key => splitLocation(key).territory)).size === selection.length,
    'Collect from at most one positive pile per entered territory.');
  return [...selection];
}
export function quoteSandmasterMovement(
  g: Game | GameView,
  player: string,
  move: SandmasterOrder,
  value: unknown,
): SandmasterMovement {
  const p = g.players.find((p) => p.id === player),
    leader = sandmasterLeader(g, player);
  requireMove(
    sandmasterModeSupported(g) &&
      leader &&
      p &&
      g.phase === 5 &&
      g.active === player,
    'Sandmaster collection needs its living native trainer and an ordinary supported movement.',
  );
  requireMove(
    record(value) &&
      Object.keys(value).sort().join(',') === 'collect,routes' &&
      record(value.routes) &&
      Array.isArray(value.collect),
    'Choose Sandmaster routes and optional collection territories.',
  );
  const physical = move.group.map(([key]) => key);
  const sources = sandmasterOrderSources(move);
  requireMove(
    sources.length > 0 &&
      new Set(physical).size === physical.length &&
      JSON.stringify(Object.keys(value.routes).sort()) ===
        JSON.stringify([...sources].sort()),
    'Every moving source sector needs its own Sandmaster route.',
  );
  const routes: Record<string, string[]> = {};
  for (const from of sources) {
    const route = value.routes[from];
    requireMove(
      Array.isArray(route) &&
        route.every((k) => typeof k === 'string') &&
        route[0] === from &&
        route.at(-1) === location(move.to, move.sector) &&
        sandmasterRouteDistance(g, route) <= move.range &&
        route.every((key) => !sandmasterPathBlocked(g, player, from, key)),
      'Sandmaster needs a connected route within movement range, outside blocked sectors.',
    );
    routes[from] = [...route];
  }
  const collect = value.collect;
  const offered = sandmasterCollectionPiles(g, routes);
  requireMove(
    collect.every(key => typeof key === 'string' &&
      offered[splitLocation(key).territory]?.includes(key)) &&
      new Set(collect.map(key => splitLocation(key).territory)).size === collect.length,
    'Choose at most one positive pile per entered territory, or decline its collection.',
  );
  return {
    leader,
    turn: g.turn,
    move: p.moved ?? 0,
    order: JSON.stringify(move),
    routes,
    collect: [...collect],
    piles: collect.map((key) => ({ key, before: g.spice[key] })),
  };
}
export function validateSandmasterMovement(
  g: Game,
  player: string,
  move: SandmasterOrder,
  saved: SandmasterMovement,
): void {
  requireMove(record(saved), 'The saved Sandmaster movement is missing.');
  const current = quoteSandmasterMovement(g, player, move, {
    routes: saved.routes,
    collect: saved.collect,
  });
  requireMove(
    JSON.stringify(saved) === JSON.stringify(current),
    'The saved Sandmaster movement or board spice has changed.',
  );
}

/** A deterministic shortest route is a default; humans can choose a different legal route. */
export function sandmasterShortestRoute(
  g: Game | GameView,
  player: string,
  from: string,
  to: string,
  range: number,
): string[] | null {
  if (sandmasterPathBlocked(g, player, from, from)) return null;
  const queue = [{ route: [from], cost: 0 }],
    best = new Map([[from, 0]]);
  while (queue.length) {
    queue.sort((a, b) => a.cost - b.cost || a.route.length - b.route.length);
    const { route, cost } = queue.shift()!,
      last = route.at(-1)!;
    if (cost !== best.get(last)) continue;
    if (last === to) return route;
    for (const key of sandmasterAdjacent(g, last)) {
      if (sandmasterPathBlocked(g, player, from, key)) continue;
      const next =
        cost +
        Number(splitLocation(last).territory !== splitLocation(key).territory);
      if (next <= range && next < (best.get(key) ?? Infinity)) {
        best.set(key, next);
        queue.push({ route: [...route, key], cost: next });
      }
    }
  }
  return null;
}
export function sandmasterActionOrder(
  g: GameView,
  player: string,
  action: Action,
): SandmasterOrder | null {
  const p = g.players.find((p) => p.id === player);
  if (
    !p || player !== g.me ||
    action.type !== 'move' ||
    action.planetologist !== undefined
  )
    return null;
  const kind = action.discoveryOrnithopter !== undefined ? 'discovery'
    : action.movementCard !== undefined ? action.ornithopter : 'ordinary';
  if (kind !== 'ordinary' && kind !== 'discovery' && kind !== 'range3' && kind !== 'twoGroups') return null;
  const transport = movementFlightSelection(g, kind);
  if (transport.blocked || ['movementCard', 'ornithopter', 'ornithopterEvent', 'discoveryOrnithopter']
    .some(key => action[key] !== transport.fields[key])) return null;
  const entries = action.forces !== undefined
    ? record(action.forces) ? Object.entries(action.forces) : null
    : typeof action.from === 'string' ? [[action.from, action.amount] as const] : null;
  if (!entries || typeof action.territory !== 'string' || !Number.isSafeInteger(action.sector) ||
    !validGameLocation(g, action.territory, action.sector as number)) return null;
  const group: [string, number][] = [], eliteGroup: Record<string, number> = {};
  for (const [key, count] of entries) {
    const at = splitLocation(key), owned = p.forces[key] ?? 0, ownedElite = p.elites?.forces[key] ?? 0;
    if (!Number.isSafeInteger(count) || (count as number) < 0 || (count as number) > owned ||
      key !== location(at.territory, at.sector) || !validGameLocation(g, at.territory, at.sector)) return null;
    if (!count) continue;
    const minimum = Math.max(0, (count as number) - (owned - ownedElite));
    const elite = (action.forces !== undefined
      ? record(action.eliteForces) ? action.eliteForces[key] : undefined : action.elite) ?? minimum;
    if (!Number.isSafeInteger(elite) || (elite as number) < minimum ||
      (elite as number) > Math.min(count as number, ownedElite)) return null;
    group.push([key, count as number]); eliteGroup[key] = elite as number;
  }
  const info = g.richeseNoField?.owner === player ? g.richeseNoField : null;
  const marker = info?.private?.deployed;
  const noField: MovementMarker | undefined = action.noField === undefined ? undefined
    : info && marker?.controller === player && isBoardNoFieldLocation(marker.location) && marker.tokenId === action.noField && info.event === action.event
      ? { tokenId: marker.tokenId, event: info.event,
        from: location(marker.location.territory, marker.location.sector) } : undefined;
  if (action.noField !== undefined && (!noField || g.homeworldMobility?.noFieldMovementBlocked)) return null;
  const origins = new Set([...group.map(([key]) => splitLocation(key).territory),
    ...(noField ? [splitLocation(noField.from).territory] : [])]);
  if (origins.size !== 1) return null;
  if (transport.cohort) {
    try { validateCohortSelection(transport.cohort, p.forces, p.elites?.forces ?? {},
      Object.fromEntries(group), eliteGroup, noField); }
    catch { return null; }
  }
  const elite = Object.values(eliteGroup).reduce((a, b) => a + b, 0);
  const frame = g.ornithopter;
  const flight: SandmasterFlight | undefined = typeof transport.fields.discoveryOrnithopter === 'string'
    ? { kind: 'discovery', token: transport.fields.discoveryOrnithopter,
      acquiredTurn: g.discoveryOrnithopter!.acquiredTurn }
    : typeof transport.fields.movementCard === 'string' || typeof transport.fields.ornithopterEvent === 'string'
      ? { kind: 'physical', card: frame!.card.id,
        mode: frame!.active?.mode ?? kind as OrnithopterMode,
        completed: frame!.active?.completed ?? 0,
        ...(frame!.active ? { event: frame!.active.event } : {}) } : undefined;
  return {
    group,
    eliteGroup,
    elite,
    origin: [...origins][0],
    to: action.territory,
    sector: action.sector as number,
    range: transport.rangeOverride ?? botMovementRange(g, p, elite),
    ...(noField ? { noField } : {}),
    ...(flight ? { flight } : {}),
  };
}
export function sandmasterDefaultChoice(
  g: GameView,
  player: string,
  action: Action,
): SandmasterChoice | null {
  if (!sandmasterModeSupported(g) || !sandmasterLeader(g, player)) return null;
  const move = sandmasterActionOrder(g, player, action);
  if (!move) return null;
  const routes: Record<string, string[]> = {};
  for (const from of sandmasterOrderSources(move)) {
    const route = sandmasterShortestRoute(
      g,
      player,
      from,
      location(move.to, move.sector),
      move.range,
    );
    if (!route) return null;
    routes[from] = route;
  }
  return { routes, collect: Object.values(sandmasterCollectionPiles(g, routes)).map(piles => piles[0]) };
}