import { TERRITORIES } from './board';
import {
  parseMixedActionExpression,
  type CompiledMixedAction,
  type MixedActionExpression,
} from './mixed-action-question';
import { MovementClaimError, parseMovementClaim } from './movement-promises';
import { parseShipmentClaim, ShipmentClaimError } from './shipment-promises';
import type { TruthFact } from './truthtrance';

export const TRAVEL_MAX_DEPTH = 4;
export const TRAVEL_MAX_LEAVES = 16;

/** Shipment leaves all describe one original future reserve-shipment event. */
export type TravelActionClaim = { kind: 'ship' | 'move'; territory: string; minimum: number };
export type TravelClaim = { turn: number; mixed: MixedActionExpression<TravelActionClaim> };
export type TravelEvent = { territory: string; amount: number };
export type TravelBranchLeaf = TravelActionClaim & { answer: boolean };
export type TravelPromise = TravelClaim & {
  event: string;
  player: string;
  asker: string;
  answer: boolean;
  /** Private residual: facts are frozen at this answer, never reevaluated. */
  compiled: CompiledMixedAction<TravelActionClaim>;
  shipment: { pending: boolean; event: TravelEvent | null };
  /** Largest actual physical ground group per destination after this answer. */
  progress: { territory: string; maximum: number }[];
  movementClosed: boolean;
  fulfilled: boolean;
  released: boolean;
};

export class TravelPromiseError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'TravelPromiseError';
  }
}

function check(value: unknown, message: string): asserts value {
  if (!value) throw new TravelPromiseError(message);
}
function object(value: unknown): value is Record<string, unknown> {
  return !!value && typeof value === 'object' && !Array.isArray(value);
}
const keys = (value: Record<string, unknown>, expected: string): boolean =>
  Object.keys(value).sort().join(',') === expected;
const identifier = (value: unknown): value is string =>
  typeof value === 'string' && value.length > 0 && value === value.trim();
const turnNumber = (value: unknown): value is number =>
  typeof value === 'number' && Number.isSafeInteger(value) && value >= 1;
const physical = (value: unknown): value is number =>
  typeof value === 'number' && Number.isSafeInteger(value) && value >= 0 && value <= 20;
const printedTerritory = (value: unknown): value is string =>
  typeof value === 'string' && TERRITORIES.some(destination => destination.id === value);

/** Only original kind/minimum/destination fields cross the question boundary. */
export function parseTravelActionClaim(value: unknown): TravelActionClaim {
  check(object(value) && keys(value, 'kind,minimum,territory') &&
    (value.kind === 'ship' || value.kind === 'move'),
  'Choose one reserve shipment or physical ground movement, with only its minimum and printed destination.');
  try {
    const claim = value.kind === 'ship' ? parseShipmentClaim(value) : parseMovementClaim(value);
    // parseShipmentClaim receives a flat leaf above, never its expression form.
    return { kind: value.kind, territory: claim.territory!, minimum: claim.minimum! };
  } catch (error) {
    if (error instanceof ShipmentClaimError || error instanceof MovementClaimError)
      throw new TravelPromiseError(error.message);
    throw error;
  }
}

/** Fact source authority remains with Truthtrance's game-aware fact decoder.
 * Here the raw tree is retained and bounded, without reading private answers. */
function storedFact(value: unknown, depth = 0): TruthFact {
  check(object(value) && identifier(value.kind) && depth <= TRAVEL_MAX_DEPTH &&
    value.kind !== 'constant' && value.kind !== 'action' && value.kind !== 'fact',
  'Retain the original current-fact statement.');
  if (value.kind === 'and' || value.kind === 'or') {
    check(keys(value, 'kind,terms') && Array.isArray(value.terms) &&
      value.terms.length >= 2 && value.terms.length <= TRAVEL_MAX_LEAVES,
    'Retain a bounded original current-fact group.');
    return { kind: value.kind, terms: value.terms.map(term => storedFact(term, depth + 1)) };
  }
  return value as unknown as TruthFact;
}

function actionKey(action: TravelActionClaim): string {
  return `${action.kind}:${action.territory}:${action.minimum}`;
}

function readCompiled(value: unknown, originals: ReadonlySet<string>): CompiledMixedAction<TravelActionClaim> {
  let leaves = 0;
  const read = (input: unknown, depth: number): CompiledMixedAction<TravelActionClaim> => {
    check(object(input) && depth <= TRAVEL_MAX_DEPTH,
      'Retain the bounded private answer-time travel expression.');
    if (input.kind === 'and' || input.kind === 'or') {
      check(keys(input, 'kind,terms') && Array.isArray(input.terms) && input.terms.length >= 2 &&
        input.terms.length <= TRAVEL_MAX_LEAVES,
      'Retain the private answer-time AND/OR travel groups.');
      return { kind: input.kind, terms: input.terms.map(term => read(term, depth + 1)) };
    }
    check(++leaves <= TRAVEL_MAX_LEAVES, 'Retain at most sixteen private travel clauses.');
    if (input.kind === 'constant') {
      check(keys(input, 'kind,value') && typeof input.value === 'boolean',
        'Retain a definite private frozen fact answer.');
      return { kind: 'constant', value: input.value };
    }
    check(input.kind === 'action' && keys(input, 'action,kind'),
      'Retain a private frozen fact or original travel action.');
    const action = parseTravelActionClaim(input.action);
    check(originals.has(actionKey(action)), 'A private travel clause must come from the original question.');
    return { kind: 'action', action };
  };
  return read(value, 0);
}

function validateEvent(event: unknown): asserts event is TravelEvent {
  check(object(event) && keys(event, 'amount,territory') && printedTerritory(event.territory) && physical(event.amount),
    'Retain the printed destination and zero to twenty actual physical forces.');
}

function readPromise(promise: TravelPromise): CompiledMixedAction<TravelActionClaim> {
  check(object(promise) && turnNumber(promise.turn), 'Retain the travel commitment and its current turn.');
  const mixed = parseMixedActionExpression(promise.mixed, storedFact, parseTravelActionClaim, { requireFact: false });
  const originals = new Set<string>();
  const destinations = new Set<string>();
  const visit = (node: MixedActionExpression<TravelActionClaim>): void => {
    if (node.kind === 'action') {
      originals.add(actionKey(node.action));
      if (node.action.kind === 'move') destinations.add(node.action.territory);
    } else if (node.kind !== 'fact') node.terms.forEach(visit);
  };
  visit(mixed);
  const compiled = readCompiled(promise.compiled, originals);
  check(typeof promise.answer === 'boolean' && typeof promise.fulfilled === 'boolean' &&
    typeof promise.released === 'boolean' && typeof promise.movementClosed === 'boolean' &&
    !(promise.fulfilled && promise.released),
  'Retain a definite whole travel answer and lifecycle.');
  check(object(promise.shipment) && keys(promise.shipment, 'event,pending') &&
    typeof promise.shipment.pending === 'boolean' &&
    (!promise.shipment.pending || promise.shipment.event === null) &&
    (!promise.movementClosed || !promise.shipment.pending),
  'Retain this answer’s single pending or received reserve shipment.');
  if (promise.shipment.event !== null) validateEvent(promise.shipment.event);
  check(Array.isArray(promise.progress), 'Retain this answer’s physical ground-movement maxima.');
  const seen = new Set<string>();
  for (const entry of promise.progress) {
    check(object(entry) && keys(entry, 'maximum,territory') && printedTerritory(entry.territory) &&
      destinations.has(entry.territory) && physical(entry.maximum) && !seen.has(entry.territory),
    'Retain unique named movement destinations and actual physical group maxima.');
    seen.add(entry.territory);
  }
  return compiled;
}

function actionValue(action: TravelActionClaim, promise: TravelPromise): boolean {
  if (action.kind === 'ship') return promise.shipment.event !== null &&
    promise.shipment.event.territory === action.territory && promise.shipment.event.amount >= action.minimum;
  return (promise.progress.find(entry => entry.territory === action.territory)?.maximum ?? 0) >= action.minimum;
}

function evaluate(node: CompiledMixedAction<TravelActionClaim>, promise: TravelPromise): boolean {
  if (node.kind === 'constant') return node.value;
  if (node.kind === 'action') return actionValue(node.action, promise);
  return node.kind === 'and' ? node.terms.every(term => evaluate(term, promise)) :
    node.terms.some(term => evaluate(term, promise));
}

/** Current value uses this record's actual future events, never projected sums. */
export function travelPromiseValue(promise: TravelPromise): boolean {
  return evaluate(readPromise(promise), promise);
}

export function liveTravelPromises<T extends TravelPromise>(promises: readonly T[], player: string, turn: number): T[] {
  check(Array.isArray(promises) && promises.every((promise): boolean => object(promise)) && identifier(player) && turnNumber(turn),
    'Choose the travel respondent and turn.');
  return promises.filter(promise => promise.player === player && promise.turn === turn &&
    !promise.fulfilled && !promise.released);
}

function mergeBranches(left: TravelBranchLeaf[], right: TravelBranchLeaf[]): TravelBranchLeaf[] | null {
  const merged = left.map(leaf => ({ ...leaf }));
  for (const leaf of right) {
    const same = merged.find(other => other.kind === leaf.kind && other.territory === leaf.territory &&
      other.answer === leaf.answer);
    if (same) same.minimum = leaf.answer ? Math.max(same.minimum, leaf.minimum) : Math.min(same.minimum, leaf.minimum);
    else merged.push({ ...leaf });
    const yes = merged.find(other => other.kind === leaf.kind && other.territory === leaf.territory && other.answer);
    const no = merged.find(other => other.kind === leaf.kind && other.territory === leaf.territory && !other.answer);
    if (yes && no && yes.minimum >= no.minimum) return null;
    // One reserve shipment cannot have two different printed destinations.
    if (leaf.kind === 'ship' && leaf.answer && merged.some(other =>
      other.kind === 'ship' && other.answer && other.territory !== leaf.territory)) return null;
  }
  return merged;
}

/** Lazy signed DNF. A whole No negates the whole tree; no branch is selected
 * at answer time. Native quotes still decide physical feasibility and routes. */
export function* travelBranches(promise: TravelPromise): Generator<TravelBranchLeaf[]> {
  const compiled = readPromise(promise);
  if (promise.fulfilled || promise.released) { yield []; return; }
  function* alternatives(node: CompiledMixedAction<TravelActionClaim>, answer: boolean): Generator<TravelBranchLeaf[]> {
    if (node.kind === 'constant') { if (node.value === answer) yield []; return; }
    if (node.kind === 'action') {
      const achieved = actionValue(node.action, promise);
      const closed = node.action.kind === 'ship' ? !promise.shipment.pending : promise.movementClosed;
      if (achieved || closed) { if (achieved === answer) yield []; return; }
      yield [{ ...node.action, answer }];
      return;
    }
    const conjunction = node.kind === 'and' ? answer : !answer;
    if (!conjunction) {
      for (const term of node.terms) yield* alternatives(term, answer);
      return;
    }
    const terms = node.terms;
    function* combine(index: number, prefix: TravelBranchLeaf[]): Generator<TravelBranchLeaf[]> {
      if (index === terms.length) { yield prefix; return; }
      for (const suffix of alternatives(terms[index], answer)) {
        const merged = mergeBranches(prefix, suffix);
        if (merged) yield* combine(index + 1, merged);
      }
    }
    yield* combine(0, []);
  }
  yield* alternatives(compiled, promise.answer);
}

function settle<T extends TravelPromise>(promise: T, update: T): T {
  const satisfied = travelPromiseValue(update);
  check(promise.answer || !satisfied, 'This travel action conflicts with your whole Truthtrance travel No answer.');
  return promise.answer && satisfied ? { ...update, fulfilled: true } : update;
}

/** Call once for the completed ordinary reserve shipment, or its actual skip.
 * A later answer starts with pending=false and never receives an older event. */
export function recordTravelShipment<T extends TravelPromise>(promises: readonly T[], player: string, turn: number,
  event: TravelEvent | null): T[] {
  if (event !== null) validateEvent(event);
  const live = liveTravelPromises(promises, player, turn);
  const updates = new Map<T, T>();
  for (const promise of live) {
    readPromise(promise);
    if (!promise.shipment.pending) continue;
    updates.set(promise, settle(promise, { ...promise,
      shipment: { pending: false, event: event === null ? null : { ...event } } }));
  }
  return promises.map(promise => updates.get(promise) ?? promise);
}

/** Call only for an actual ordinary physical ground group. Several smaller
 * groups never combine into one minimum; markers and shipments do not count. */
export function recordTravelMovement<T extends TravelPromise>(promises: readonly T[], player: string, turn: number,
  event: TravelEvent): T[] {
  validateEvent(event);
  const updates = new Map<T, T>();
  for (const promise of liveTravelPromises(promises, player, turn)) {
    readPromise(promise);
    if (promise.movementClosed || event.amount === 0) continue;
    let named = false;
    const visit = (node: MixedActionExpression<TravelActionClaim>): void => {
      if (node.kind === 'action') named ||= node.action.kind === 'move' && node.action.territory === event.territory;
      else if (node.kind !== 'fact') node.terms.forEach(visit);
    };
    visit(promise.mixed);
    if (!named) continue;
    const old = promise.progress.find(entry => entry.territory === event.territory)?.maximum ?? 0;
    if (event.amount <= old) continue;
    const progress = promise.progress.map(entry => ({ ...entry }));
    const entry = progress.find(candidate => candidate.territory === event.territory);
    if (entry) entry.maximum = event.amount;
    else progress.push({ territory: event.territory, maximum: event.amount });
    updates.set(promise, settle(promise, { ...promise, progress }));
  }
  return promises.map(promise => updates.get(promise) ?? promise);
}

/** Close this actual respondent's travel turn. Ending cannot evade a Yes. */
export function finishTravelTurn<T extends TravelPromise>(promises: readonly T[], player: string, turn: number): T[] {
  liveTravelPromises(promises, player, turn);
  return promises.map(promise => {
    if (promise.player !== player || promise.turn !== turn) return promise;
    readPromise(promise);
    const closed = { ...promise, movementClosed: true, shipment: { ...promise.shipment, pending: false } };
    check(promise.released || travelPromiseValue(closed) === promise.answer,
      'Complete your whole Truthtrance travel Yes answer before ending movement.');
    return { ...closed, fulfilled: !promise.released };
  });
}

/** Validate stored structure/progress; game-aware raw fact authority and native
 * movement/shipment legality remain the integrating engine's responsibility. */
export function validateTravelPromises(promises: readonly TravelPromise[], players: readonly string[]): void {
  check(Array.isArray(promises) && Array.isArray(players), 'Retain the travel commitment records and participants.');
  const events = new Set<string>();
  for (const promise of promises) {
    const compiled = readPromise(promise);
    const satisfied = evaluate(compiled, promise);
    check(identifier(promise.event) && !events.has(promise.event) && identifier(promise.player) && identifier(promise.asker) &&
      players.includes(promise.player) && players.includes(promise.asker) && promise.player !== promise.asker &&
      (promise.released || (promise.answer || !satisfied) &&
        (!promise.answer || promise.fulfilled === satisfied) &&
        (!promise.fulfilled || satisfied === promise.answer) &&
        (!promise.movementClosed || promise.fulfilled)),
    'The travel commitment lost its event, participants or whole-answer progress.');
    events.add(promise.event);
  }
}