import { BadRequestException } from '@nestjs/common';
import ExcelJS from 'exceljs';

export function cellStr(value: ExcelJS.CellValue | undefined): string {
  try {
    if (value == null) return '';
    if (typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean') {
      return String(value).trim();
    }
    if (value instanceof Date) {
      return Number.isNaN(value.getTime()) ? '' : value.toISOString();
    }
    if (typeof value === 'object' && 'richText' in value && Array.isArray(value.richText)) {
      return value.richText.map((part) => part?.text ?? '').join('').trim();
    }
    if (typeof value === 'object' && 'text' in value && typeof value.text === 'string') {
      return value.text.trim();
    }
    if (typeof value === 'object' && 'result' in value && value.result != null) {
      const result = value.result;
      if (typeof result === 'string' || typeof result === 'number' || typeof result === 'boolean') {
        return String(result).trim();
      }
      if (result instanceof Date) {
        return Number.isNaN(result.getTime()) ? '' : result.toISOString();
      }
      return '';
    }
    if (typeof value === 'object' && 'error' in value && value.error != null) {
      return String(value.error).trim();
    }
    return '';
  } catch {
    return '';
  }
}

export function normalizeHeader(raw: string) {
  return raw
    .trim()
    .toLowerCase()
    .replace(/[_-]+/g, '')
    .replace(/‌/g, '')
    .replace(/\s+/g, '')
    .replace(/[()]/g, '');
}

export function stripHtml(raw: string) {
  return raw
    .replace(/<br\s*\/?>/gi, '\n')
    .replace(/&nbsp;/gi, ' ')
    .replace(/<[^>]+>/g, ' ')
    .replace(/\s+/g, ' ')
    .trim();
}

export function toAsciiDigits(value: string) {
  return value
    .replace(/[۰-۹]/g, (d) => String('۰۱۲۳۴۵۶۷۸۹'.indexOf(d)))
    .replace(/[٠-٩]/g, (d) => String('٠١٢٣٤٥٦٧٨٩'.indexOf(d)));
}

function div(a: number, b: number) {
  return Math.trunc(a / b);
}

function mod(a: number, b: number) {
  return a - Math.trunc(a / b) * b;
}

export function toJalali(gy: number, gm: number, gd: number) {
  const gdm = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
  const gy2 = gm > 2 ? gy + 1 : gy;
  let days =
    355666 +
    365 * gy +
    div(gy2 + 3, 4) -
    div(gy2 + 99, 100) +
    div(gy2 + 399, 400) +
    gd +
    gdm[gm - 1];
  let jy = -1595 + 33 * div(days, 12053);
  days %= 12053;
  jy += 4 * div(days, 1461);
  days %= 1461;
  if (days > 365) {
    jy += div(days - 1, 365);
    days = (days - 1) % 365;
  }
  const jm = days < 186 ? 1 + div(days, 31) : 7 + div(days - 186, 30);
  const jd = 1 + (days < 186 ? days % 31 : (days - 186) % 30);
  return { jy, jm, jd };
}

export function toGregorian(jy: number, jm: number, jd: number) {
  const jy2 = jy + 1595;
  let days =
    -355668 +
    365 * jy2 +
    div(jy2, 33) * 8 +
    div(mod(jy2, 33) + 3, 4) +
    jd +
    (jm < 7 ? (jm - 1) * 31 : (jm - 7) * 30 + 186);
  let gy = 400 * div(days, 146097);
  days %= 146097;
  if (days > 36524) {
    gy += 100 * div(--days, 36524);
    days %= 36524;
    if (days >= 365) days += 1;
  }
  gy += 4 * div(days, 1461);
  days %= 1461;
  if (days > 365) {
    gy += div(days - 1, 365);
    days = (days - 1) % 365;
  }
  const gd = days + 1;
  const salA = [
    0,
    31,
    (gy % 4 === 0 && gy % 100 !== 0) || gy % 400 === 0 ? 29 : 28,
    31,
    30,
    31,
    30,
    31,
    31,
    30,
    31,
    30,
    31,
  ];
  let gm = 0;
  let gDay = gd;
  for (let i = 1; i <= 12; i += 1) {
    const v = salA[i]!;
    if (gDay <= v) {
      gm = i;
      break;
    }
    gDay -= v;
  }
  return { gy, gm, gd: gDay };
}

export function formatJalaliDate(d: Date | string | null | undefined) {
  if (!d) return '';
  const date = typeof d === 'string' ? new Date(d) : d;
  if (Number.isNaN(date.getTime())) return '';
  const { jy, jm, jd } = toJalali(date.getFullYear(), date.getMonth() + 1, date.getDate());
  return `${jy}/${String(jm).padStart(2, '0')}/${String(jd).padStart(2, '0')}`;
}

export function formatClock(d: Date | string | null | undefined) {
  if (!d) return '';
  const date = typeof d === 'string' ? new Date(d) : d;
  if (Number.isNaN(date.getTime())) return '';
  return `${String(date.getHours()).padStart(2, '0')}:${String(date.getMinutes()).padStart(2, '0')}`;
}

export function parseAmount(raw?: string): number | null {
  const text = toAsciiDigits(raw ?? '')
    .replace(/[,،]/g, '')
    .replace(/\s+/g, '')
    .trim();
  if (!text) return null;
  const n = Number(text.replace(/[^\d.-]/g, ''));
  return Number.isFinite(n) ? n : null;
}

export function parseJalaliDateTime(dateRaw?: string, timeRaw?: string): Date | null {
  const dateText = toAsciiDigits(dateRaw ?? '').trim();
  if (!dateText) return null;
  const match = /^(\d{3,4})[\/\-](\d{1,2})[\/\-](\d{1,2})$/.exec(dateText);
  if (!match) {
    const fallback = new Date(dateText);
    return Number.isNaN(fallback.getTime()) ? null : fallback;
  }
  const jy = Number(match[1]);
  const jm = Number(match[2]);
  const jd = Number(match[3]);
  const { gy, gm, gd } = toGregorian(jy, jm, jd);
  let hh = 0;
  let mm = 0;
  const timeText = toAsciiDigits(timeRaw ?? '').trim();
  const tm = /^(\d{1,2}):(\d{2})/.exec(timeText);
  if (tm) {
    hh = Number(tm[1]);
    mm = Number(tm[2]);
  }
  return new Date(gy, gm - 1, gd, hh, mm, 0, 0);
}

export async function workbookFromUpload(file: Express.Multer.File | undefined) {
  if (!file?.buffer?.length) {
    throw new BadRequestException('فایل اکسل انتخاب نشده است');
  }
  const wb = new ExcelJS.Workbook();
  try {
    // Pass Node Buffer directly — Uint8Array copies can break ExcelJS on some runtimes.
    await wb.xlsx.load(file.buffer as unknown as ExcelJS.Buffer);
  } catch (err) {
    const detail = err instanceof Error ? err.message : '';
    throw new BadRequestException(
      detail.includes('central directory') || detail.includes('zip')
        ? 'فایل اکسل نامعتبر است. فقط فرمت .xlsx پشتیبانی می‌شود (نه .xls یا csv).'
        : 'خواندن فایل اکسل ناموفق بود. فایل را با فرمت .xlsx ذخیره کنید و دوباره تلاش کنید.',
    );
  }
  const sheet = wb.worksheets[0];
  if (!sheet) throw new BadRequestException('شیت اکسل پیدا نشد');
  return sheet;
}

export type ExcelFieldOption = {
  key: string;
  label: string;
  required?: boolean;
};

export type ExcelColumnPreview = {
  header: string;
  index: number;
  samples: string[];
};

export type ExcelPreviewResult = {
  columns: ExcelColumnPreview[];
  fields: ExcelFieldOption[];
  suggested: Record<string, string>;
  needsMapping: boolean;
};

export function excelFieldsFromColumns(
  columns: Array<{ header: string; key: string }>,
  requiredKeys: string[] = [],
): ExcelFieldOption[] {
  const seen = new Set<string>();
  const fields: ExcelFieldOption[] = [];
  for (const col of columns) {
    if (!col.key || col.key === '_type' || seen.has(col.key)) continue;
    seen.add(col.key);
    fields.push({
      key: col.key,
      label: col.header,
      required: requiredKeys.includes(col.key),
    });
  }
  return fields;
}

export function parseExcelMapping(raw?: string): Record<string, string> | undefined {
  if (raw == null || !String(raw).trim()) return undefined;
  try {
    const parsed = JSON.parse(String(raw)) as unknown;
    if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) {
      throw new Error('invalid');
    }
    const mapping: Record<string, string> = {};
    for (const [header, field] of Object.entries(parsed as Record<string, unknown>)) {
      if (typeof field === 'string' && field.trim()) mapping[header] = field.trim();
    }
    return mapping;
  } catch {
    throw new BadRequestException('نگاشت ستون‌ها نامعتبر است');
  }
}

function resolveFieldKey(
  raw: string,
  aliases: Record<string, string>,
  mapping?: Record<string, string>,
) {
  if (mapping) {
    return mapping[raw] || mapping[normalizeHeader(raw)] || '';
  }
  const compact = normalizeHeader(raw);
  return aliases[compact] ?? aliases[raw.trim()] ?? aliases[normalizeHeader(raw)] ?? '';
}

export async function previewExcel(
  file: Express.Multer.File,
  aliases: Record<string, string>,
  fields: ExcelFieldOption[],
): Promise<ExcelPreviewResult> {
  const sheet = await workbookFromUpload(file);
  const headerRow = sheet.getRow(1);
  const columns: ExcelColumnPreview[] = [];
  const suggested: Record<string, string> = {};
  const used = new Set<string>();

  headerRow.eachCell((cell, col) => {
    const header = cellStr(cell.value);
    if (!header) return;
    const samples: string[] = [];
    const last = Math.min(sheet.rowCount, 6);
    for (let r = 2; r <= last; r += 1) {
      const value = cellStr(sheet.getRow(r).getCell(col).value);
      if (value) samples.push(value);
      if (samples.length >= 3) break;
    }
    columns.push({ header, index: col, samples });
    const key = resolveFieldKey(header, aliases);
    if (key && !used.has(key)) {
      suggested[header] = key;
      used.add(key);
    }
  });

  if (!columns.length) {
    throw new BadRequestException('ستون عنوان در ردیف اول فایل پیدا نشد');
  }

  const required = fields.filter((f) => f.required).map((f) => f.key);
  const mapped = new Set(Object.values(suggested));
  const missingRequired = required.some((key) => !mapped.has(key));
  const unrecognized = columns.some((col) => !suggested[col.header]);
  return {
    columns,
    fields,
    suggested,
    needsMapping: unrecognized || missingRequired || !mapped.size,
  };
}

export async function readMappedRows(
  file: Express.Multer.File,
  aliases: Record<string, string>,
  mapping?: Record<string, string>,
): Promise<Record<string, string>[]> {
  const sheet = await workbookFromUpload(file);
  const headerRow = sheet.getRow(1);
  const map = new Map<number, string>();
  headerRow.eachCell((cell, col) => {
    const raw = cellStr(cell.value);
    if (!raw) return;
    const key = resolveFieldKey(raw, aliases, mapping);
    if (key) map.set(col, key);
  });
  if (!map.size) {
    throw new BadRequestException(
      'ستون‌های فایل شناسایی نشد. ستون‌های فایل را با فیلدهای سیستم تطبیق دهید.',
    );
  }

  const rows: Record<string, string>[] = [];
  sheet.eachRow((row, rowNumber) => {
    if (rowNumber === 1) return;
    const item: Record<string, string> = {};
    let any = false;
    for (const [col, key] of map) {
      const value = cellStr(row.getCell(col).value);
      if (value) any = true;
      if (value || item[key] == null) item[key] = value;
    }
    if (any) rows.push(item);
  });
  if (!rows.length) {
    throw new BadRequestException('هیچ ردیف داده‌ای در فایل نیست');
  }
  return rows;
}

export async function writeXlsx(
  sheetName: string,
  columns: Array<{ header: string; key: string; width?: number }>,
  rows: Array<Record<string, string | number | null | undefined>>,
): Promise<Buffer> {
  const wb = new ExcelJS.Workbook();
  const sheet = wb.addWorksheet(sheetName);
  sheet.columns = columns;
  for (const row of rows) sheet.addRow(row);
  const buf = await wb.xlsx.writeBuffer();
  return Buffer.from(buf);
}