import * as XLSX from 'xlsx';
import { type IFileParser, type ParsedSheet } from '@/application/ports/output/IFileParser';

export class SheetJSFileParser implements IFileParser {
  async parse(file: File): Promise<ParsedSheet[]> {
    const extension = file.name.substring(file.name.lastIndexOf('.')).toLowerCase();

    if (extension === '.json') {
      return this.parseJSON(file);
    }

    const buffer = await file.arrayBuffer();
    const workbook = XLSX.read(buffer, { type: 'array' });
    const sheets: ParsedSheet[] = [];

    for (const sheetName of workbook.SheetNames) {
      const worksheet = workbook.Sheets[sheetName];
      const jsonData = XLSX.utils.sheet_to_json<Record<string, any>>(worksheet, {
        defval: '',
      });

      const range = XLSX.utils.decode_range(worksheet['!ref'] ?? 'A1');
      const columns: string[] = [];
      for (let col = range.s.c; col <= range.e.c; col++) {
        const cellAddress = XLSX.utils.encode_cell({ r: range.s.r, c: col });
        const cell = worksheet[cellAddress];
        columns.push(cell ? String(cell.v) : `Column${col + 1}`);
      }

      sheets.push({
        sheetName,
        columns,
        rows: jsonData,
      });
    }

    return sheets;
  }

  getSupportedFormats(): string[] {
    return ['.xlsx', '.xls', '.csv', '.json'];
  }

  private async parseJSON(file: File): Promise<ParsedSheet[]> {
    const text = await file.text();
    const parsed = JSON.parse(text);
    const dataArray: Record<string, any>[] = Array.isArray(parsed) ? parsed : [parsed];
    const columns = dataArray.length > 0 ? Object.keys(dataArray[0]) : [];

    return [
      {
        sheetName: file.name.replace(/\.json$/i, ''),
        columns,
        rows: dataArray,
      },
    ];
  }
}