import { MAP_H, MAP_W, indexOf, inside } from "./grid.js";
import { hash2 } from "./random.js";

export const NAME_KANJI_POOLS = {
  modifiers: [],
  inlandTerrain: [],
  waterTerrain: [],
  coastalTerrain: [],
  plants: [],
  postfixes: [],
  archaicPrefixes: [],
  archaicSuffixes: [],
  settlementWords: [],
};

export const NAME_PROBABILITIES = {
  customName: 0.20,
  forcedName: 1.0,
  retryCount: 24,

  categoryFallback: {
    modifiers: 1.0,
    inlandTerrain: 1.0,
    waterTerrain: 1.0,
    coastalTerrain: 1.0,
    plants: 1.0,
    postfixes: 1.0,
    archaicPrefixes: 1.0,
    archaicSuffixes: 1.0,
    settlementWords: 1.0,
  },

  contextCategoryWeights: {
    generic: {
      inlandTerrain: 1.0,
      waterTerrain: 0.6,
      coastalTerrain: 0.2,
      plants: 0.8,
      postfixes: 0.7,
      archaic: 0.25,
      settlementWords: 0.6,
    },
    coastal: {
      inlandTerrain: 0.25,
      waterTerrain: 0.8,
      coastalTerrain: 1.0,
      plants: 0.5,
      postfixes: 0.7,
      archaic: 0.2,
      settlementWords: 0.6,
    },
    river: {
      inlandTerrain: 0.5,
      waterTerrain: 1.0,
      coastalTerrain: 0.1,
      plants: 0.6,
      postfixes: 0.7,
      archaic: 0.25,
      settlementWords: 0.6,
    },
    plain: {
      inlandTerrain: 1.0,
      waterTerrain: 0.35,
      coastalTerrain: 0.05,
      plants: 0.9,
      postfixes: 0.8,
      archaic: 0.25,
      settlementWords: 0.7,
    },
    mountain: {
      inlandTerrain: 1.0,
      waterTerrain: 0.45,
      coastalTerrain: 0.02,
      plants: 0.85,
      postfixes: 0.55,
      archaic: 0.35,
      settlementWords: 0.45,
    },
    historic: {
      inlandTerrain: 0.65,
      waterTerrain: 0.45,
      coastalTerrain: 0.25,
      plants: 0.6,
      postfixes: 0.9,
      archaic: 0.75,
      settlementWords: 0.9,
    },
    suburban: {
      inlandTerrain: 0.85,
      waterTerrain: 0.25,
      coastalTerrain: 0.15,
      plants: 0.55,
      postfixes: 0.85,
      archaic: 0.10,
      settlementWords: 1.0,
    },
  },
};

export const NAME_TEMPLATES = {
  modifierTerrain: {
    slots: ["modifier", "terrain"],
    baseWeight: 1.0,
  },
  plantTerrain: {
    slots: ["plant", "terrain"],
    baseWeight: 0.85,
  },
  terrainPostfix: {
    slots: ["terrain", "postfix"],
    baseWeight: 0.75,
  },
  archaicPair: {
    slots: ["archaicPrefix", "archaicSuffix"],
    baseWeight: 0.35,
  },
  archaicTerrain: {
    slots: ["archaicPrefix", "terrain"],
    baseWeight: 0.30,
  },
  modifierSettlement: {
    slots: ["modifier", "settlement"],
    baseWeight: 0.65,
  },
};

export const NAME_TEMPLATE_WEIGHTS = {
  generic: {
    modifierTerrain: 1.0,
    plantTerrain: 0.8,
    terrainPostfix: 0.7,
    archaicPair: 0.25,
    archaicTerrain: 0.25,
    modifierSettlement: 0.55,
  },
  coastal: {
    modifierTerrain: 0.8,
    plantTerrain: 0.55,
    terrainPostfix: 0.9,
    archaicPair: 0.2,
    archaicTerrain: 0.25,
    modifierSettlement: 0.55,
  },
  river: {
    modifierTerrain: 0.9,
    plantTerrain: 0.85,
    terrainPostfix: 0.85,
    archaicPair: 0.25,
    archaicTerrain: 0.25,
    modifierSettlement: 0.55,
  },
  plain: {
    modifierTerrain: 1.0,
    plantTerrain: 0.95,
    terrainPostfix: 0.8,
    archaicPair: 0.25,
    archaicTerrain: 0.25,
    modifierSettlement: 0.7,
  },
  mountain: {
    modifierTerrain: 1.0,
    plantTerrain: 0.9,
    terrainPostfix: 0.5,
    archaicPair: 0.35,
    archaicTerrain: 0.45,
    modifierSettlement: 0.35,
  },
  historic: {
    modifierTerrain: 0.6,
    plantTerrain: 0.45,
    terrainPostfix: 0.75,
    archaicPair: 0.8,
    archaicTerrain: 0.55,
    modifierSettlement: 0.95,
  },
  suburban: {
    modifierTerrain: 0.85,
    plantTerrain: 0.45,
    terrainPostfix: 0.65,
    archaicPair: 0.1,
    archaicTerrain: 0.1,
    modifierSettlement: 1.0,
  },
};

export const CUSTOM_NAMES = {};
export const FORCED_NAMES = {};

// Legacy export kept only so older imports do not fail.
export const NAME_PARTS = {};

const POOL_KEYS = Object.keys(NAME_KANJI_POOLS);
const TERRAIN_POOL_KEYS = ["inlandTerrain", "waterTerrain", "coastalTerrain"];
const ASCII_DIAGNOSTIC_PREFIX = "N";

function stableHash(value) {
  const text = String(value || "");
  let h = 2166136261;
  for (let i = 0; i < text.length; i++) {
    h ^= text.charCodeAt(i);
    h = Math.imul(h, 16777619) >>> 0;
  }
  return h >>> 0;
}

function roll(seed, id, attempt, salt) {
  const h = stableHash(id);
  return hash2(h + attempt * 1009 + salt * 9173, seed + salt * 1013, (h ^ seed ^ salt) >>> 0);
}

function pick(pool, seed, id, attempt, salt) {
  if (!pool?.length) return null;
  const index = Math.floor(roll(seed, id, attempt, salt) * pool.length) % pool.length;
  return pool[index] || null;
}

function countChars(value) {
  return Array.from(String(value || "")).length;
}

function incrementCounter(counter, key, amount = 1) {
  counter[key] = (counter[key] || 0) + amount;
}

function boundedIndex(entity) {
  const x = Math.max(0, Math.min(MAP_W - 1, Math.round(entity?.x || 0)));
  const y = Math.max(0, Math.min(MAP_H - 1, Math.round(entity?.y || 0)));
  return indexOf(x, y);
}

function isNearSea(x, y, sea, radius = 3) {
  if (!sea) return false;
  for (let dy = -radius; dy <= radius; dy++) {
    for (let dx = -radius; dx <= radius; dx++) {
      const nx = x + dx;
      const ny = y + dy;
      if (inside(nx, ny) && sea[indexOf(nx, ny)]) return true;
    }
  }
  return false;
}

function contextWeightsFor(context, probabilities = NAME_PROBABILITIES) {
  return probabilities.contextCategoryWeights?.[context] || probabilities.contextCategoryWeights?.generic || {};
}

function poolWeight(poolKey, context, probabilities = NAME_PROBABILITIES) {
  const weights = contextWeightsFor(context, probabilities);
  const fallback = probabilities.categoryFallback?.[poolKey] ?? 1.0;
  if (poolKey === "archaicPrefixes" || poolKey === "archaicSuffixes") return (weights.archaic ?? 1.0) * fallback;
  return (weights[poolKey] ?? 1.0) * fallback;
}

function slotPoolKeys(slot, context, probabilities = NAME_PROBABILITIES) {
  if (slot === "terrain") {
    return weightedKeyOrder(TERRAIN_POOL_KEYS, context, probabilities, 113);
  }
  const map = {
    modifier: "modifiers",
    plant: "plants",
    postfix: "postfixes",
    archaicPrefix: "archaicPrefixes",
    archaicSuffix: "archaicSuffixes",
    settlement: "settlementWords",
  };
  return map[slot] ? [map[slot]] : [];
}

function weightedKeyOrder(keys, context, probabilities, salt) {
  return [...keys].sort((a, b) => {
    const wa = poolWeight(a, context, probabilities);
    const wb = poolWeight(b, context, probabilities);
    if (wb !== wa) return wb - wa;
    return stableHash(`${a}:${salt}`) - stableHash(`${b}:${salt}`);
  });
}

function weightedChoice(entries, seed, id, attempt, salt) {
  const active = entries.filter((entry) => entry.weight > 0);
  const total = active.reduce((sum, entry) => sum + entry.weight, 0);
  if (total <= 0) return null;
  let target = roll(seed, id, attempt, salt) * total;
  for (const entry of active) {
    target -= entry.weight;
    if (target <= 0) return entry.key;
  }
  return active[active.length - 1]?.key || null;
}

function pickWeightedPoolKey(keys, context, pools, probabilities, seed, id, attempt, salt) {
  const entries = keys.map((key) => ({
    key,
    weight: poolWeight(key, context, probabilities) * (pools[key]?.length ? 1 : 0),
  }));
  return weightedChoice(entries, seed, id, attempt, salt);
}

export function createNameDebug(probabilities = NAME_PROBABILITIES, pools = NAME_KANJI_POOLS) {
  const emptyPools = POOL_KEYS.filter((key) => !pools[key]?.length);
  const poolsPresent = Object.fromEntries(POOL_KEYS.map((key) => [key, Boolean(pools[key]?.length)]));
  return {
    effectiveCustomNameProbability: probabilities.customName,
    poolsPresent,
    emptyPools,
    selectedTemplateCounts: {},
    selectedContextCounts: {},
    customNamesUsed: 0,
    forcedNamesUsed: 0,
    generatedNamesUsed: 0,
    invalidNamesRejected: 0,
    oneCharacterNamesPrevented: 0,
    duplicateRetries: 0,
    fallbackAttempts: 0,
    legacyFallbackUsed: 0,
  };
}

export function chooseNameContext(entity, fields) {
  const kind = String(entity?.kind || "").toLowerCase();
  const i = boundedIndex(entity);
  const coastal = (fields?.coastalLowland?.[i] || 0) > 0.35 || isNearSea(entity?.x || 0, entity?.y || 0, fields?.sea);
  const river = (fields?.river?.[i] || 0) > 0.35 || (fields?.flowAccum?.[i] || 0) > 0.55 || (fields?.valleyField?.[i] || 0) > 0.42;
  const plain = (fields?.plain?.[i] || 0) > 0.48 || (fields?.agriculture?.[i] || 0) > 0.46;
  const mountain = (fields?.elevation?.[i] || 0) > 0.52 || (fields?.slope?.[i] || 0) > 0.35 || (fields?.ridgeField?.[i] || 0) > 0.42;
  const urban = (fields?.populationDensity?.[i] || 0) > 0.35 || [2, 3, 4, 7, 8].includes(fields?.landuse?.[i]);

  if (kind.includes("port") || kind.includes("harbor") || entity?.portClass) return "coastal";
  if (kind.includes("crossing") || kind.includes("bridge")) return "river";
  if (kind.includes("pass") || kind.includes("mountain")) return "mountain";
  if (kind.includes("castle") || kind.includes("market")) return "historic";
  if (kind.includes("newtown") || kind.includes("new town") || kind.includes("satellite") || kind.includes("station") || urban) return "suburban";
  if (coastal && !mountain) return "coastal";
  if (river) return "river";
  if (mountain && !plain) return "mountain";
  if (plain) return "plain";
  return "generic";
}

export function resolveSlotPool(slot, context, pools = NAME_KANJI_POOLS, probabilities = NAME_PROBABILITIES, seed = 0, id = "", attempt = 0) {
  const keys = slotPoolKeys(slot, context, probabilities);
  if (!keys.length) return null;
  const selectedKey = pickWeightedPoolKey(keys, context, pools, probabilities, seed, id, attempt, 1501 + stableHash(slot));
  if (selectedKey) return { key: selectedKey, pool: pools[selectedKey] };
  for (const key of weightedKeyOrder(keys, context, probabilities, 1559)) {
    if (pools[key]?.length) return { key, pool: pools[key] };
  }
  return null;
}

export function validateGeneratedName(name, options = {}) {
  const value = String(name || "");
  const length = countChars(value);
  if (!value) return { valid: false, reason: "empty" };
  if (value.includes("\uFFFD")) return { valid: false, reason: "replacement" };
  if (!options.allowAsciiDiagnostic && value.startsWith(ASCII_DIAGNOSTIC_PREFIX) && /^N[0-9A-Z]+$/.test(value)) {
    return { valid: false, reason: "asciiDiagnostic" };
  }
  if (!options.allowOneCharacter && length < 2) return { valid: false, reason: "oneCharacter" };
  if (!options.allowLong && length > 4) return { valid: false, reason: "tooLong" };
  return { valid: true, reason: "valid" };
}

function chooseTemplate(context, seed, id, attempt) {
  const contextWeights = NAME_TEMPLATE_WEIGHTS[context] || NAME_TEMPLATE_WEIGHTS.generic;
  const entries = Object.entries(NAME_TEMPLATES).map(([key, template]) => ({
    key,
    weight: (template.baseWeight ?? 1.0) * (contextWeights?.[key] ?? 0),
  }));
  return weightedChoice(entries, seed, id, attempt, 2003);
}

function generateTemplateNameDetails(seed, id, entity, fields, attempt, usedNames, pools = NAME_KANJI_POOLS, probabilities = NAME_PROBABILITIES) {
  const context = chooseNameContext(entity, fields);
  const templateKey = chooseTemplate(context, seed, id, attempt);
  const template = NAME_TEMPLATES[templateKey];
  if (!template) return { name: null, context, templateKey: null };

  const parts = [];
  for (let slotIndex = 0; slotIndex < template.slots.length; slotIndex++) {
    const slot = template.slots[slotIndex];
    const slotPool = resolveSlotPool(slot, context, pools, probabilities, seed, id, attempt + slotIndex);
    if (!slotPool?.pool?.length) return { name: null, context, templateKey };
    const part = pick(slotPool.pool, seed, id, attempt, 2503 + slotIndex * 127 + stableHash(slotPool.key));
    if (!part) return { name: null, context, templateKey };
    parts.push(part);
  }

  const name = parts.join("");
  const validation = validateGeneratedName(name);
  if (!validation.valid) return { name: null, context, templateKey, invalidReason: validation.reason };
  if (usedNames?.has(name)) return { name: null, context, templateKey, duplicate: true };
  return { name, context, templateKey };
}

export function generateTemplateName(seed, id, entity, fields, attempt = 0, usedNames = null) {
  return generateTemplateNameDetails(seed, id, entity, fields, attempt, usedNames).name;
}

function deterministicDiagnosticName(seed, id, attempt = 0) {
  const h = Math.floor(roll(seed, id, attempt, 3001) * 0xb640).toString(36).toUpperCase();
  return `${ASCII_DIAGNOSTIC_PREFIX}${h.padStart(3, "0")}`;
}

function uniqueDiagnosticName(seed, id, usedNames, debug, startAttempt = 0) {
  for (let offset = 0; offset < 128; offset++) {
    const name = deterministicDiagnosticName(seed, id, startAttempt + offset);
    if (!usedNames?.has(name)) return name;
    debug.duplicateRetries++;
  }
  return `${ASCII_DIAGNOSTIC_PREFIX}${stableHash(`${seed}:${id}`).toString(36).toUpperCase()}`;
}

function tryCustomName(seed, id, usedNames, debug) {
  const customName = CUSTOM_NAMES[id];
  if (!customName) return null;
  if (roll(seed, id, 0, 3501) >= NAME_PROBABILITIES.customName) return null;
  const validation = validateGeneratedName(customName, { allowAsciiDiagnostic: true });
  if (!validation.valid) {
    if (validation.reason === "oneCharacter") debug.oneCharacterNamesPrevented++;
    else debug.invalidNamesRejected++;
    return null;
  }
  if (usedNames?.has(customName)) {
    debug.duplicateRetries++;
    return null;
  }
  debug.customNamesUsed++;
  return customName;
}

export function generateEntityName(seed, id, entity, fields, usedNames = null, debug = createNameDebug()) {
  debug ||= createNameDebug();
  const forcedName = FORCED_NAMES[id];
  if (forcedName) {
    debug.forcedNamesUsed++;
    return forcedName;
  }

  const customName = tryCustomName(seed, id, usedNames, debug);
  if (customName) return customName;

  const retryCount = Math.max(1, NAME_PROBABILITIES.retryCount || 1);
  for (let attempt = 0; attempt < retryCount; attempt++) {
    const result = generateTemplateNameDetails(seed, id, entity, fields, attempt, usedNames);
    if (result.context) incrementCounter(debug.selectedContextCounts, result.context);
    if (result.templateKey) incrementCounter(debug.selectedTemplateCounts, result.templateKey);
    if (result.duplicate) {
      debug.duplicateRetries++;
      continue;
    }
    if (result.invalidReason) {
      if (result.invalidReason === "oneCharacter") debug.oneCharacterNamesPrevented++;
      else debug.invalidNamesRejected++;
      continue;
    }
    if (result.name) {
      debug.generatedNamesUsed++;
      return result.name;
    }
  }

  debug.fallbackAttempts++;
  return uniqueDiagnosticName(seed, id, usedNames, debug, retryCount);
}

export function contextualDefaultName(seed, id, entity, nameParts = NAME_PARTS, fields, attempt = 0) {
  const name = generateTemplateName(seed, id, entity, fields, attempt, null);
  return name || deterministicDiagnosticName(seed, id, attempt);
}

export function chooseNameSuffixPool() {
  return NAME_KANJI_POOLS.postfixes;
}