/* =============================================================================
 * spreadsheet_functions_lookup.ts  (주인 B · misc 700 줄 넘어 2026-09-27 쪼갬)
 * 찾기 · 조건부 세기·합·평균·최대·최소 함수. `spreadsheet_functions_misc.ts` 에서
 * VLOOKUP · HLOOKUP · INDEX · MATCH · CHOOSE · COUNT · COUNTA · COUNTIF · SUMIF ·
 * SUMIFS · COUNTIFS · AVERAGEIF(S) · MAXIFS · MINIFS · IFS · SWITCH · XLOOKUP 를 옮겨 옴.
 * 형 바꾸기 도우미는 `spreadsheet_functions_math.ts` 공용 것을 씀.
 * ========================================================================== */

import {
  ZERO,
  add,
  cmp,
  div,
  frac,
  parseDecimal,
  type Frac,
} from "@ui/sheet/ui_template_sheet_frac";
import type { ErrorValue, LazyArg, RangeValue, Scalar, SheetFunction } from "./spreadsheet_types";
import {
  bool,
  collectNumbers,
  fracToDouble,
  isErr,
  isFrac,
  isRange,
  mkErr,
  num,
  toNumber,
  toScalar,
} from "./spreadsheet_functions_math";

const ONE = frac(1n);

// ── 값 견줌(찾기 · 세기 함수 공용) ───────────────────────────────────────────

function typeRank(v: Scalar): number {
  if (v === null) return -1;
  if (isFrac(v)) return 0;
  if (typeof v === "string") return 1;
  if (typeof v === "boolean") return 2;
  return 3;
}

function compareScalars(a: Scalar, b: Scalar): number {
  if (isFrac(a) && isFrac(b)) return cmp(a, b);
  if (typeof a === "string" && typeof b === "string") {
    const la = a.toUpperCase();
    const lb = b.toUpperCase();
    return la < lb ? -1 : la > lb ? 1 : 0;
  }
  if (typeof a === "boolean" && typeof b === "boolean") return a === b ? 0 : a ? 1 : -1;
  return 0;
}

function equalScalars(a: Scalar, b: Scalar): boolean {
  return typeRank(a) === typeRank(b) && compareScalars(a, b) === 0;
}

function wrapScalar(v: Scalar): RangeValue {
  return { kind: "range", rows: 1, cols: 1, at: () => v };
}

// ── 조건 글(`>10` · `<=5` · `사과*`) ─────────────────────────────────────────

function wildcardToRegex(text: string): RegExp {
  const escaped = text
    .replace(/[.+^${}()|[\]\\]/g, "\\$&")
    .replace(/\*/g, ".*")
    .replace(/\?/g, ".");
  return new RegExp(`^${escaped}$`, "i");
}

function parseCriteria(crit: Scalar): (cell: Scalar) => boolean {
  if (crit === null) return (cell) => cell === null;
  if (typeof crit === "boolean") return (cell) => typeof cell === "boolean" && cell === crit;
  if (isFrac(crit)) return (cell) => isFrac(cell) && cmp(cell, crit) === 0;
  if (isErr(crit)) return () => false;
  const m = /^(<=|>=|<>|<|>|=)?(.*)$/.exec(crit);
  const op = m?.[1] ?? "";
  const rest = m?.[2] ?? crit;
  let numRest: Frac | null = null;
  try {
    numRest = rest.trim() === "" ? null : parseDecimal(rest);
  } catch {
    numRest = null;
  }
  if (numRest !== null) {
    const nr = numRest;
    return (cell) => {
      if (!isFrac(cell)) return false;
      const c = cmp(cell, nr);
      if (op === "<=") return c <= 0;
      if (op === ">=") return c >= 0;
      if (op === "<>") return c !== 0;
      if (op === "<") return c < 0;
      if (op === ">") return c > 0;
      return c === 0;
    };
  }
  const pat = wildcardToRegex(rest);
  if (op === "<>") return (cell) => !(typeof cell === "string" && pat.test(cell));
  return (cell) => typeof cell === "string" && pat.test(cell);
}

/** `args[from]` 부터 (범위,조건) 짝을 이어가며 모두 맞는 자리만 참 — *IFS 함수 공용.
 * `shape` 범위와 크기가 다른 조건 범위가 있으면 `#VALUE!`. */
function criteriaMask(args: LazyArg[], from: number, shape: RangeValue): boolean[] | ErrorValue {
  const mask = new Array<boolean>(shape.rows * shape.cols).fill(true);
  for (let i = from; i + 1 < args.length; i += 2) {
    const rangeArg = args[i]();
    if (!isRange(rangeArg)) return mkErr("#VALUE!");
    if (rangeArg.rows !== shape.rows || rangeArg.cols !== shape.cols) {
      return mkErr("#VALUE!", "조건 범위 크기가 다름");
    }
    const crit = toScalar(args[i + 1]());
    if (isErr(crit)) return crit;
    const pred = parseCriteria(crit);
    let k = 0;
    for (let r = 0; r < shape.rows; r++) {
      for (let c = 0; c < shape.cols; c++) {
        if (mask[k] && !pred(rangeArg.at(r, c))) mask[k] = false;
        k++;
      }
    }
  }
  return mask;
}

// ── 함수 표 ──────────────────────────────────────────────────────────────

export const LOOKUP_FUNCTIONS: Record<string, SheetFunction> = {
  VLOOKUP: {
    min: 3,
    max: 4,
    call: (args) => {
      const lookup = toScalar(args[0]());
      if (isErr(lookup)) return lookup;
      const table = args[1]();
      if (!isRange(table)) return mkErr("#VALUE!");
      const colN = num(args[2]());
      if (isErr(colN)) return colN;
      const col = Math.trunc(fracToDouble(colN)) - 1;
      if (col < 0 || col >= table.cols) return mkErr("#REF!");
      const approxRaw = args.length > 3 ? bool(args[3]()) : true;
      if (isErr(approxRaw)) return approxRaw;
      if (approxRaw) {
        let best = -1;
        for (let r = 0; r < table.rows; r++) {
          const key = table.at(r, 0);
          if (typeRank(key) !== typeRank(lookup)) {
            if (best >= 0) break;
            continue;
          }
          if (compareScalars(key, lookup) <= 0) best = r;
          else break;
        }
        if (best < 0) return mkErr("#N/A");
        return table.at(best, col);
      }
      for (let r = 0; r < table.rows; r++) {
        if (equalScalars(table.at(r, 0), lookup)) return table.at(r, col);
      }
      return mkErr("#N/A");
    },
  },
  HLOOKUP: {
    min: 3,
    max: 4,
    call: (args) => {
      const lookup = toScalar(args[0]());
      if (isErr(lookup)) return lookup;
      const table = args[1]();
      if (!isRange(table)) return mkErr("#VALUE!");
      const rowN = num(args[2]());
      if (isErr(rowN)) return rowN;
      const row = Math.trunc(fracToDouble(rowN)) - 1;
      if (row < 0 || row >= table.rows) return mkErr("#REF!");
      const approxRaw = args.length > 3 ? bool(args[3]()) : true;
      if (isErr(approxRaw)) return approxRaw;
      if (approxRaw) {
        let best = -1;
        for (let c = 0; c < table.cols; c++) {
          const key = table.at(0, c);
          if (typeRank(key) !== typeRank(lookup)) {
            if (best >= 0) break;
            continue;
          }
          if (compareScalars(key, lookup) <= 0) best = c;
          else break;
        }
        if (best < 0) return mkErr("#N/A");
        return table.at(row, best);
      }
      for (let c = 0; c < table.cols; c++) {
        if (equalScalars(table.at(0, c), lookup)) return table.at(row, c);
      }
      return mkErr("#N/A");
    },
  },
  INDEX: {
    min: 2,
    max: 3,
    call: (args) => {
      const rangeArg = args[0]();
      if (isErr(rangeArg)) return rangeArg;
      const range = isRange(rangeArg) ? rangeArg : wrapScalar(rangeArg);
      const rowN = num(args[1]());
      if (isErr(rowN)) return rowN;
      const row = Math.trunc(fracToDouble(rowN));
      const colN = args.length > 2 ? num(args[2]()) : frac(range.cols === 1 ? 1n : 0n);
      if (isErr(colN)) return colN;
      const col = Math.trunc(fracToDouble(colN));
      if (row === 0 && col === 0) return mkErr("#VALUE!");
      if (row === 0) {
        if (col < 1 || col > range.cols) return mkErr("#REF!");
        const c = col - 1;
        return { kind: "range", rows: range.rows, cols: 1, at: (r: number) => range.at(r, c) };
      }
      if (col === 0) {
        if (row < 1 || row > range.rows) return mkErr("#REF!");
        const r = row - 1;
        return {
          kind: "range",
          rows: 1,
          cols: range.cols,
          at: (_r: number, c: number) => range.at(r, c),
        };
      }
      if (row < 1 || row > range.rows || col < 1 || col > range.cols) return mkErr("#REF!");
      return range.at(row - 1, col - 1);
    },
  },
  MATCH: {
    min: 2,
    max: 3,
    call: (args) => {
      const lookup = toScalar(args[0]());
      if (isErr(lookup)) return lookup;
      const rangeArg = args[1]();
      if (!isRange(rangeArg)) return mkErr("#VALUE!");
      if (rangeArg.rows !== 1 && rangeArg.cols !== 1) {
        return mkErr("#VALUE!", "한 줄 · 한 칸짜리 범위만");
      }
      const n = rangeArg.rows === 1 ? rangeArg.cols : rangeArg.rows;
      const at = (i: number): Scalar =>
        rangeArg.rows === 1 ? rangeArg.at(0, i) : rangeArg.at(i, 0);
      const modeN = args.length > 2 ? num(args[2]()) : ONE;
      if (isErr(modeN)) return modeN;
      const mode = Math.trunc(fracToDouble(modeN));
      if (mode === 0) {
        for (let i = 0; i < n; i++) if (equalScalars(at(i), lookup)) return frac(BigInt(i + 1));
        return mkErr("#N/A");
      }
      let best = -1;
      for (let i = 0; i < n; i++) {
        const key = at(i);
        if (typeRank(key) !== typeRank(lookup)) {
          if (best >= 0) break;
          continue;
        }
        const c = compareScalars(key, lookup);
        if (mode > 0 ? c <= 0 : c >= 0) best = i;
        else break;
      }
      if (best < 0) return mkErr("#N/A");
      return frac(BigInt(best + 1));
    },
  },
  CHOOSE: {
    min: 2,
    call: (args) => {
      const idxN = num(args[0]());
      if (isErr(idxN)) return idxN;
      const idx = Math.trunc(fracToDouble(idxN));
      if (idx < 1 || idx > args.length - 1) return mkErr("#VALUE!");
      return args[idx]();
    },
  },
  COUNT: {
    min: 0,
    call: (args) => {
      const values = collectNumbers(args, false, false);
      return isErr(values) ? values : frac(BigInt(values.length));
    },
  },
  COUNTA: {
    min: 0,
    call: (args) => {
      let count = 0;
      for (const a of args) {
        const v = a();
        if (isRange(v)) {
          for (let r = 0; r < v.rows; r++) {
            for (let c = 0; c < v.cols; c++) if (v.at(r, c) !== null) count++;
          }
        } else if (v !== null) {
          count++;
        }
      }
      return frac(BigInt(count));
    },
  },
  COUNTIF: {
    min: 2,
    max: 2,
    call: (args) => {
      const range = args[0]();
      if (!isRange(range)) return mkErr("#VALUE!");
      const crit = toScalar(args[1]());
      if (isErr(crit)) return crit;
      const pred = parseCriteria(crit);
      let count = 0;
      for (let r = 0; r < range.rows; r++) {
        for (let c = 0; c < range.cols; c++) if (pred(range.at(r, c))) count++;
      }
      return frac(BigInt(count));
    },
  },
  SUMIF: {
    min: 2,
    max: 3,
    call: (args) => {
      const range = args[0]();
      if (!isRange(range)) return mkErr("#VALUE!");
      const crit = toScalar(args[1]());
      if (isErr(crit)) return crit;
      const pred = parseCriteria(crit);
      const sumRange = args.length > 2 ? args[2]() : range;
      if (!isRange(sumRange)) return mkErr("#VALUE!");
      if (sumRange.rows !== range.rows || sumRange.cols !== range.cols) {
        return mkErr("#VALUE!", "합 범위 크기가 다름");
      }
      let total = ZERO;
      for (let r = 0; r < range.rows; r++) {
        for (let c = 0; c < range.cols; c++) {
          if (!pred(range.at(r, c))) continue;
          const n = toNumber(sumRange.at(r, c));
          if (isErr(n)) return n;
          total = add(total, n);
        }
      }
      return total;
    },
  },
  SUMIFS: {
    min: 3,
    call: (args) => {
      const sumRange = args[0]();
      if (!isRange(sumRange)) return mkErr("#VALUE!");
      const mask = criteriaMask(args, 1, sumRange);
      if (isErr(mask)) return mask;
      let total = ZERO;
      let k = 0;
      for (let r = 0; r < sumRange.rows; r++) {
        for (let c = 0; c < sumRange.cols; c++) {
          if (mask[k]) {
            const n = toNumber(sumRange.at(r, c));
            if (isErr(n)) return n;
            total = add(total, n);
          }
          k++;
        }
      }
      return total;
    },
  },
  COUNTIFS: {
    min: 2,
    call: (args) => {
      const first = args[0]();
      if (!isRange(first)) return mkErr("#VALUE!");
      const mask = criteriaMask(args, 0, first);
      if (isErr(mask)) return mask;
      return frac(BigInt(mask.filter(Boolean).length));
    },
  },
  AVERAGEIF: {
    min: 2,
    max: 3,
    call: (args) => {
      const range = args[0]();
      if (!isRange(range)) return mkErr("#VALUE!");
      const crit = toScalar(args[1]());
      if (isErr(crit)) return crit;
      const pred = parseCriteria(crit);
      const avgRange = args.length > 2 ? args[2]() : range;
      if (!isRange(avgRange)) return mkErr("#VALUE!");
      if (avgRange.rows !== range.rows || avgRange.cols !== range.cols) {
        return mkErr("#VALUE!", "평균 범위 크기가 다름");
      }
      let total = ZERO;
      let count = 0;
      for (let r = 0; r < range.rows; r++) {
        for (let c = 0; c < range.cols; c++) {
          if (!pred(range.at(r, c))) continue;
          const n = toNumber(avgRange.at(r, c));
          if (isErr(n)) return n;
          total = add(total, n);
          count++;
        }
      }
      return count === 0 ? mkErr("#DIV/0!") : div(total, frac(BigInt(count)));
    },
  },
  AVERAGEIFS: {
    min: 3,
    call: (args) => {
      const avgRange = args[0]();
      if (!isRange(avgRange)) return mkErr("#VALUE!");
      const mask = criteriaMask(args, 1, avgRange);
      if (isErr(mask)) return mask;
      let total = ZERO;
      let count = 0;
      let k = 0;
      for (let r = 0; r < avgRange.rows; r++) {
        for (let c = 0; c < avgRange.cols; c++) {
          if (mask[k]) {
            const n = toNumber(avgRange.at(r, c));
            if (isErr(n)) return n;
            total = add(total, n);
            count++;
          }
          k++;
        }
      }
      return count === 0 ? mkErr("#DIV/0!") : div(total, frac(BigInt(count)));
    },
  },
  MAXIFS: {
    min: 3,
    call: (args) => {
      const targetRange = args[0]();
      if (!isRange(targetRange)) return mkErr("#VALUE!");
      const mask = criteriaMask(args, 1, targetRange);
      if (isErr(mask)) return mask;
      let best: Frac | null = null;
      let k = 0;
      for (let r = 0; r < targetRange.rows; r++) {
        for (let c = 0; c < targetRange.cols; c++) {
          if (mask[k]) {
            const cell = targetRange.at(r, c);
            if (isFrac(cell) && (best === null || cmp(cell, best) > 0)) best = cell;
          }
          k++;
        }
      }
      return best ?? ZERO;
    },
  },
  MINIFS: {
    min: 3,
    call: (args) => {
      const targetRange = args[0]();
      if (!isRange(targetRange)) return mkErr("#VALUE!");
      const mask = criteriaMask(args, 1, targetRange);
      if (isErr(mask)) return mask;
      let best: Frac | null = null;
      let k = 0;
      for (let r = 0; r < targetRange.rows; r++) {
        for (let c = 0; c < targetRange.cols; c++) {
          if (mask[k]) {
            const cell = targetRange.at(r, c);
            if (isFrac(cell) && (best === null || cmp(cell, best) < 0)) best = cell;
          }
          k++;
        }
      }
      return best ?? ZERO;
    },
  },
  IFS: {
    min: 2,
    call: (args) => {
      for (let i = 0; i + 1 < args.length; i += 2) {
        const c = bool(args[i]());
        if (isErr(c)) return c;
        if (c) return args[i + 1]();
      }
      return mkErr("#N/A");
    },
  },
  SWITCH: {
    min: 3,
    call: (args) => {
      const target = toScalar(args[0]());
      if (isErr(target)) return target;
      let i = 1;
      for (; i + 1 < args.length; i += 2) {
        const cand = toScalar(args[i]());
        if (isErr(cand)) return cand;
        if (equalScalars(target, cand)) return args[i + 1]();
      }
      return i < args.length ? args[i]() : mkErr("#N/A");
    },
  },
  XLOOKUP: {
    min: 3,
    max: 6,
    call: (args) => {
      const lookup = toScalar(args[0]());
      if (isErr(lookup)) return lookup;
      const lookupRange = args[1]();
      const returnRange = args[2]();
      if (!isRange(lookupRange) || !isRange(returnRange)) return mkErr("#VALUE!");
      const n = lookupRange.rows * lookupRange.cols;
      if (n !== returnRange.rows * returnRange.cols) {
        return mkErr("#VALUE!", "찾을 범위 · 돌려줄 범위 크기가 다름");
      }
      const at = (rv: RangeValue, i: number): Scalar => (rv.rows === 1 ? rv.at(0, i) : rv.at(i, 0));
      const modeN = args.length > 4 ? num(args[4]()) : ZERO;
      if (isErr(modeN)) return modeN;
      const mode = Math.trunc(fracToDouble(modeN));
      const searchN = args.length > 5 ? num(args[5]()) : ONE;
      if (isErr(searchN)) return searchN;
      const reverse = Math.trunc(fracToDouble(searchN)) < 0;
      let best = -1;
      for (let step = 0; step < n; step++) {
        const i = reverse ? n - 1 - step : step;
        const key = at(lookupRange, i);
        if (typeRank(key) !== typeRank(lookup)) continue;
        const c = compareScalars(key, lookup);
        if (c === 0) {
          best = i;
          break;
        }
        if (mode === 1 && c > 0) {
          if (best < 0 || compareScalars(key, at(lookupRange, best)) < 0) best = i;
        } else if (mode === -1 && c < 0) {
          if (best < 0 || compareScalars(key, at(lookupRange, best)) > 0) best = i;
        }
      }
      if (best < 0) return args.length > 3 ? args[3]() : mkErr("#N/A");
      return at(returnRange, best);
    },
  },
};