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

export const CUSTOMERS_SHEET_NAME = 'Customers';

export const CUSTOMER_EXCEL_HEADERS = {
  phone: 'phone',
  firstName: 'first_name',
  lastName: 'last_name',
} as const;

type HeaderKey = keyof typeof CUSTOMER_EXCEL_HEADERS;

const HEADER_ALIASES: Record<string, HeaderKey> = {
  phone: 'phone',
  cell: 'phone',
  cell_number: 'phone',
  cellnumber: 'phone',
  mobile: 'phone',
  'mobile number': 'phone',
  'phone number': 'phone',
  شماره: 'phone',
  'شماره موبایل': 'phone',
  موبایل: 'phone',
  first_name: 'firstName',
  firstname: 'firstName',
  'first name': 'firstName',
  name: 'firstName',
  نام: 'firstName',
  last_name: 'lastName',
  lastname: 'lastName',
  'last name': 'lastName',
  'نام خانوادگی': 'lastName',
};

const PERSIAN_DIGITS = '۰۱۲۳۴۵۶۷۸۹';
const ARABIC_DIGITS = '٠١٢٣٤٥٦٧٨٩';
const E164_RE = /^\+[1-9]\d{6,14}$/;

export interface CustomerExcelRow {
  phone: string;
  firstName: string;
  lastName: string;
}

export interface ParsedCustomerExcelRow {
  rowNumber: number;
  phone: string;
  firstName: string | null;
  lastName: string | null;
}

export async function buildCustomersExcel(rows: CustomerExcelRow[]): Promise<Buffer> {
  const workbook = new ExcelJS.Workbook();
  workbook.creator = 'Meshkee';
  workbook.created = new Date();

  const sheet = workbook.addWorksheet(CUSTOMERS_SHEET_NAME);
  sheet.columns = [
    { header: CUSTOMER_EXCEL_HEADERS.phone, key: 'phone', width: 16 },
    { header: CUSTOMER_EXCEL_HEADERS.firstName, key: 'firstName', width: 18 },
    { header: CUSTOMER_EXCEL_HEADERS.lastName, key: 'lastName', width: 20 },
    { width: 3 },
    { header: 'دستورالعمل', width: 48 },
    { header: 'Instructions', width: 48 },
  ];

  const header = sheet.getRow(1);
  header.height = 22;
  header.font = { bold: true, size: 11 };
  header.alignment = { vertical: 'middle' };
  for (let col = 1; col <= 3; col += 1) {
    const cell = header.getCell(col);
    cell.fill = {
      type: 'pattern',
      pattern: 'solid',
      fgColor: { argb: 'FFE8EEF7' },
    };
    cell.font = { bold: true, size: 11 };
    cell.alignment = { vertical: 'middle' };
  }
  for (let col = 5; col <= 6; col += 1) {
    const cell = header.getCell(col);
    cell.font = { bold: true, size: 11 };
    cell.alignment = { vertical: 'middle' };
  }

  for (const row of rows) {
    const added = sheet.addRow({
      phone: formatPhoneForExcel(row.phone),
      firstName: row.firstName,
      lastName: row.lastName,
    });
    added.height = 20;
    added.font = { size: 11 };

    const phoneCell = added.getCell('phone');
    phoneCell.numFmt = '@';
    phoneCell.alignment = { vertical: 'middle', readingOrder: 'ltr', horizontal: 'left' };

    const firstNameCell = added.getCell('firstName');
    firstNameCell.alignment = {
      vertical: 'middle',
      readingOrder: looksPersian(row.firstName) ? 'rtl' : 'ltr',
    };

    const lastNameCell = added.getCell('lastName');
    lastNameCell.alignment = {
      vertical: 'middle',
      readingOrder: looksPersian(row.lastName) ? 'rtl' : 'ltr',
    };
  }

  writeInstructionColumns(sheet);
  sheet.views = [{ state: 'frozen', ySplit: 1, rightToLeft: false }];

  const buffer = await workbook.xlsx.writeBuffer();
  return Buffer.from(buffer);
}

export async function parseCustomersExcel(buffer: Buffer): Promise<ParsedCustomerExcelRow[]> {
  const workbook = new ExcelJS.Workbook();
  await workbook.xlsx.load(buffer as unknown as Parameters<ExcelJS.Xlsx['load']>[0]);

  const sheet =
    workbook.getWorksheet(CUSTOMERS_SHEET_NAME) ?? workbook.worksheets[0];

  if (!sheet) {
    throw new BadRequestException('Excel file has no worksheet.');
  }

  const headerMap = readHeaderMap(sheet);
  const phoneCol = headerMap.phone;
  if (!phoneCol) {
    throw new BadRequestException(
      'Excel is missing required column: phone (or cell / mobile / شماره).',
    );
  }

  const firstNameCol = headerMap.firstName;
  const lastNameCol = headerMap.lastName;
  const rows: ParsedCustomerExcelRow[] = [];
  const seenPhones = new Set<string>();

  sheet.eachRow((row, rowNumber) => {
    if (rowNumber === 1) return;

    const rawPhone = cellText(row.getCell(phoneCol).value);
    const firstName = firstNameCol
      ? optionalName(cellText(row.getCell(firstNameCol).value))
      : null;
    const lastName = lastNameCol
      ? optionalName(cellText(row.getCell(lastNameCol).value))
      : null;

    if (!rawPhone && !firstName && !lastName) return;

    if (!rawPhone) {
      throw new BadRequestException(`Row ${rowNumber}: phone is required.`);
    }

    const phone = normalizeCellToE164(rawPhone);
    if (!phone) {
      throw new BadRequestException(
        `Row ${rowNumber}: phone "${rawPhone}" is not a valid mobile number.`,
      );
    }

    if (seenPhones.has(phone)) {
      throw new BadRequestException(
        `Row ${rowNumber}: duplicate phone "${phone}".`,
      );
    }
    seenPhones.add(phone);

    rows.push({ rowNumber, phone, firstName, lastName });
  });

  if (rows.length === 0) {
    throw new BadRequestException('Excel has no customer rows to import.');
  }

  if (rows.length > 10_000) {
    throw new BadRequestException('Excel has too many rows (max 10,000).');
  }

  return rows;
}

export function customersExcelFilename(now = new Date()) {
  const parts = new Intl.DateTimeFormat('en-GB', {
    timeZone: 'Asia/Tehran',
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit',
    hourCycle: 'h23',
  }).formatToParts(now);

  const pick = (type: Intl.DateTimeFormatPartTypes) =>
    parts.find((part) => part.type === type)?.value ?? '';

  const date = `${pick('year')}-${pick('month')}-${pick('day')}`;
  const time = `${pick('hour')}-${pick('minute')}`;
  return `customers - ${date} - ${time}.xlsx`;
}

/** Normalize Iranian/local input to E.164 (e.g. +989121111111). */
export function normalizeCellToE164(input: string): string | null {
  const trimmed = input.trim();
  if (!trimmed) return null;
  if (E164_RE.test(trimmed)) return trimmed;

  const digits = toLatinDigits(trimmed).replace(/\D/g, '');
  if (!digits) return null;

  if (digits.startsWith('98') && digits.length >= 12) {
    const value = `+${digits}`;
    return E164_RE.test(value) ? value : null;
  }

  if (digits.startsWith('0') && digits.length >= 11) {
    const value = `+98${digits.slice(1)}`;
    return E164_RE.test(value) ? value : null;
  }

  if (digits.length === 10 && digits.startsWith('9')) {
    const value = `+98${digits}`;
    return E164_RE.test(value) ? value : null;
  }

  if (/^[1-9]\d{6,14}$/.test(digits)) {
    const value = `+${digits}`;
    return E164_RE.test(value) ? value : null;
  }

  return null;
}

function writeInstructionColumns(sheet: ExcelJS.Worksheet) {
  const faLines = [
    'فقط ستون phone الزامی است.',
    'نام و نام خانوادگی اختیاری‌اند (برای شخصی‌سازی پیامک).',
    'رمز عبور لازم نیست — حساب‌های جدید با رمز تصادفی ساخته می‌شوند.',
    'فرمت شماره: 0912… یا +98912…',
    'شماره‌های تکراری در فایل یا مشتری‌های موجود نادیده گرفته می‌شوند.',
    'این فایل برای افزودن مشتری جهت ارسال پیامک است.',
  ];
  const enLines = [
    'Only the phone column is required.',
    'first_name / last_name are optional (for SMS personalization).',
    'No password column — new accounts get a random unusable password.',
    'Phone format: 0912… or +98912…',
    'Duplicates in the file or already-linked customers are skipped.',
    'Use this file to add customers for SMS sending.',
  ];

  faLines.forEach((line, index) => {
    const row = sheet.getRow(index + 2);
    if (!row.height || row.height < 20) {
      row.height = 20;
    }

    const faCell = row.getCell(5);
    faCell.value = line;
    faCell.font = { size: 11 };
    faCell.alignment = { wrapText: true, vertical: 'top', readingOrder: 'rtl' };

    const enCell = row.getCell(6);
    enCell.value = enLines[index] ?? '';
    enCell.font = { size: 11 };
    enCell.alignment = { wrapText: true, vertical: 'top', readingOrder: 'ltr' };
  });
}

/** Prefer local 09… display for Iranian numbers in the spreadsheet. */
function formatPhoneForExcel(phone: string) {
  if (phone.startsWith('+98') && phone.length === 13) {
    return `0${phone.slice(3)}`;
  }
  return phone;
}

function looksPersian(value: string) {
  return /[\u0600-\u06FF]/.test(value);
}

function readHeaderMap(sheet: ExcelJS.Worksheet): Partial<Record<HeaderKey, number>> {
  const headerRow = sheet.getRow(1);
  const map: Partial<Record<HeaderKey, number>> = {};

  headerRow.eachCell((cell, colNumber) => {
    const key = HEADER_ALIASES[normalizeHeader(cellText(cell.value))];
    if (key && !map[key]) {
      map[key] = colNumber;
    }
  });

  return map;
}

function normalizeHeader(value: string) {
  return value.trim().toLowerCase().replace(/\s+/g, ' ');
}

function optionalName(value: string): string | null {
  const trimmed = value.trim();
  return trimmed ? trimmed.slice(0, 100) : null;
}

function cellText(value: ExcelJS.CellValue): string {
  if (value == null || value === '') return '';
  if (typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean') {
    return String(value).trim();
  }
  if (value instanceof Date) return '';
  if (typeof value === 'object' && 'text' in value && typeof value.text === 'string') {
    return value.text.trim();
  }
  if (typeof value === 'object' && 'richText' in value && Array.isArray(value.richText)) {
    return value.richText.map((part) => part.text).join('').trim();
  }
  if (typeof value === 'object' && 'result' in value) {
    return cellText(value.result as ExcelJS.CellValue);
  }
  return String(value).trim();
}

function toLatinDigits(value: string) {
  return [...value]
    .map((char) => {
      const persian = PERSIAN_DIGITS.indexOf(char);
      if (persian >= 0) return String(persian);
      const arabic = ARABIC_DIGITS.indexOf(char);
      if (arabic >= 0) return String(arabic);
      return char;
    })
    .join('');
}