import type { ClassId } from "../app/characterCatalog";
import { clampPlayerLevel, MAX_PLAYER_LEVEL } from "./progression";
import {
  allocateTalentPoint,
  talentDescriptionForRank,
  talentNodeById,
  talentNodesForTree,
  talentPointsForLevel,
  talentTreeById,
  talentTreesForClass,
  type TalentRanks,
} from "./talentCatalog";

export interface PartyTalentSpecializationDefinition {
  readonly classId: ClassId;
  readonly specialization: string;
  readonly primaryTreeId: string;
}

/**
 * The exact class/spec combinations used by the deterministic dungeon-party
 * roster. Keep the tree id explicit: display names are not stable identifiers
 * and Feral (Cat) deliberately maps to the Feral Combat tree.
 */
export const PARTY_TALENT_SPECIALIZATIONS = Object.freeze([
  { classId: "warrior", specialization: "Protection", primaryTreeId: "warrior-protection" },
  { classId: "death-knight", specialization: "Blood", primaryTreeId: "death-knight-blood" },
  { classId: "paladin", specialization: "Protection", primaryTreeId: "paladin-protection" },
  { classId: "priest", specialization: "Holy", primaryTreeId: "priest-holy" },
  { classId: "paladin", specialization: "Holy", primaryTreeId: "paladin-holy" },
  { classId: "druid", specialization: "Restoration", primaryTreeId: "druid-restoration" },
  { classId: "shaman", specialization: "Restoration", primaryTreeId: "shaman-restoration" },
  { classId: "warrior", specialization: "Arms", primaryTreeId: "warrior-arms" },
  { classId: "warrior", specialization: "Fury", primaryTreeId: "warrior-fury" },
  { classId: "paladin", specialization: "Retribution", primaryTreeId: "paladin-retribution" },
  { classId: "hunter", specialization: "Marksmanship", primaryTreeId: "hunter-marksmanship" },
  { classId: "hunter", specialization: "Survival", primaryTreeId: "hunter-survival" },
  { classId: "rogue", specialization: "Combat", primaryTreeId: "rogue-combat" },
  { classId: "rogue", specialization: "Assassination", primaryTreeId: "rogue-assassination" },
  { classId: "priest", specialization: "Shadow", primaryTreeId: "priest-shadow" },
  { classId: "death-knight", specialization: "Frost", primaryTreeId: "death-knight-frost" },
  { classId: "death-knight", specialization: "Unholy", primaryTreeId: "death-knight-unholy" },
  { classId: "shaman", specialization: "Enhancement", primaryTreeId: "shaman-enhancement" },
  { classId: "shaman", specialization: "Elemental", primaryTreeId: "shaman-elemental" },
  { classId: "mage", specialization: "Arcane", primaryTreeId: "mage-arcane" },
  { classId: "mage", specialization: "Fire", primaryTreeId: "mage-fire" },
  { classId: "mage", specialization: "Frost", primaryTreeId: "mage-frost" },
  { classId: "warlock", specialization: "Affliction", primaryTreeId: "warlock-affliction" },
  { classId: "warlock", specialization: "Demonology", primaryTreeId: "warlock-demonology" },
  { classId: "druid", specialization: "Balance", primaryTreeId: "druid-balance" },
  { classId: "druid", specialization: "Feral (Cat)", primaryTreeId: "druid-feral-combat" },
] as const satisfies readonly PartyTalentSpecializationDefinition[]);

export interface PartyTalentSelection {
  /** One-based talent-point number, from 1 at level 10 through 71 at level 80. */
  readonly point: number;
  readonly level: number;
  readonly nodeId: string;
  readonly treeId: string;
  readonly treeName: string;
  readonly name: string;
  readonly rank: number;
  readonly maxRank: number;
  readonly icon: string;
  readonly description: string;
  readonly inPrimaryTree: boolean;
}

const SPEC_BY_KEY = new Map<string, PartyTalentSpecializationDefinition>(
  PARTY_TALENT_SPECIALIZATIONS.map((definition) => [
    specializationKey(definition.classId, definition.specialization),
    definition,
  ]),
);
const PLAN_BY_KEY = new Map<string, readonly PartyTalentSelection[]>();

function specializationKey(classId: ClassId, specialization: string): string {
  return `${classId}:${specialization}`;
}

export function partyTalentSpecialization(
  classId: ClassId,
  specialization: string,
): PartyTalentSpecializationDefinition | null {
  return SPEC_BY_KEY.get(specializationKey(classId, specialization)) ?? null;
}

export function partyTalentPrimaryTreeId(classId: ClassId, specialization: string): string | null {
  return partyTalentSpecialization(classId, specialization)?.primaryTreeId ?? null;
}

function requireSpecialization(
  classId: ClassId,
  specialization: string,
): PartyTalentSpecializationDefinition {
  const definition = partyTalentSpecialization(classId, specialization);
  if (!definition) throw new Error(`Unsupported party specialization: ${classId}:${specialization}`);
  return definition;
}

function orderedCandidateNodeIds(definition: PartyTalentSpecializationDefinition): readonly string[] {
  const trees = talentTreesForClass(definition.classId);
  const primary = trees.find((tree) => tree.id === definition.primaryTreeId);
  if (!primary) {
    throw new Error(`Unknown primary talent tree ${definition.primaryTreeId} for ${definition.classId}`);
  }
  return [primary, ...trees.filter((tree) => tree.id !== primary.id)]
    .flatMap((tree) => talentNodesForTree(tree.id))
    .map((node) => node.id);
}

/**
 * Produces a stable legal build without duplicating talent rules here. The
 * primary tree is exhausted in catalog row/index order before secondary trees;
 * every individual rank is accepted by the shared allocator at its real level.
 */
function buildAllocationPlan(
  definition: PartyTalentSpecializationDefinition,
): readonly PartyTalentSelection[] {
  const candidates = orderedCandidateNodeIds(definition);
  let ranks: TalentRanks = {};
  const selections: PartyTalentSelection[] = [];

  for (let level = 10; level <= MAX_PLAYER_LEVEL; level += 1) {
    let selected: PartyTalentSelection | null = null;
    for (const nodeId of candidates) {
      const node = talentNodeById(nodeId);
      if (!node || (ranks[nodeId] ?? 0) >= node.maxRank) continue;
      const allocation = allocateTalentPoint(ranks, definition.classId, nodeId, level);
      if (!allocation.ok) continue;
      ranks = allocation.ranks;
      const rank = ranks[nodeId] ?? 0;
      const tree = talentTreeById(node.treeId);
      if (!tree || rank <= 0) throw new Error(`Talent allocation lost catalog data for ${nodeId}`);
      selected = Object.freeze({
        point: selections.length + 1,
        level,
        nodeId,
        treeId: tree.id,
        treeName: tree.name,
        name: node.name,
        rank,
        maxRank: node.maxRank,
        icon: node.icon,
        description: talentDescriptionForRank(node, rank),
        inPrimaryTree: tree.id === definition.primaryTreeId,
      });
      break;
    }
    if (!selected) {
      throw new Error(`Could not allocate party talent point for ${definition.classId}:${definition.specialization} at level ${level}`);
    }
    selections.push(selected);
  }

  return Object.freeze(selections);
}

/** Returns the complete, catalog-validated 71-point level 10-80 plan. */
export function partyTalentAllocationPlan(
  classId: ClassId,
  specialization: string,
): readonly PartyTalentSelection[] {
  const definition = requireSpecialization(classId, specialization);
  const key = specializationKey(classId, specialization);
  const cached = PLAN_BY_KEY.get(key);
  if (cached) return cached;
  const plan = buildAllocationPlan(definition);
  PLAN_BY_KEY.set(key, plan);
  return plan;
}

/** Returns current node ranks for a party member at the supplied player level. */
export function partyTalentRanksForLevel(
  classId: ClassId,
  specialization: string,
  level: number,
): TalentRanks {
  const points = talentPointsForLevel(clampPlayerLevel(level));
  const ranks: Record<string, number> = {};
  for (const selection of partyTalentAllocationPlan(classId, specialization).slice(0, points)) {
    ranks[selection.nodeId] = selection.rank;
  }
  return Object.freeze(ranks);
}

/** Returns every rank learned so far, in the exact level-by-level order learned. */
export function learnedPartyTalentSelections(
  classId: ClassId,
  specialization: string,
  level: number,
): readonly PartyTalentSelection[] {
  const points = talentPointsForLevel(clampPlayerLevel(level));
  return partyTalentAllocationPlan(classId, specialization).slice(0, points);
}

/**
 * Returns the next planned ranks after `level`. Before level 10 this starts at
 * the level-10 choice; at level 80 it is empty.
 */
export function upcomingPartyTalentSelections(
  classId: ClassId,
  specialization: string,
  level: number,
  limit = 5,
): readonly PartyTalentSelection[] {
  const start = talentPointsForLevel(clampPlayerLevel(level));
  const safeLimit = Number.isFinite(limit) ? Math.max(0, Math.trunc(limit)) : 0;
  return partyTalentAllocationPlan(classId, specialization).slice(start, start + safeLimit);
}