"""ساخت XLSX به‌صورت جریانی در حافظه با stdlib، بدون openpyxl و پردازش پس‌زمینه."""
from io import BytesIO
from zipfile import ZipFile,ZIP_DEFLATED
from xml.sax.saxutils import escape
from django.http import HttpResponse

def _col(n):
    s=''
    while n:
        n,r=divmod(n-1,26);s=chr(65+r)+s
    return s

def make_xlsx(title,headings,rows,filename='samshaf.xlsx'):
    output=BytesIO()
    with ZipFile(output,'w',compression=ZIP_DEFLATED,compresslevel=6) as z:
        z.writestr('[Content_Types].xml','''<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types"><Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/><Default Extension="xml" ContentType="application/xml"/><Override PartName="/xl/workbook.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml"/><Override PartName="/xl/worksheets/sheet1.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml"/><Override PartName="/xl/styles.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml"/></Types>''')
        z.writestr('_rels/.rels','''<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/></Relationships>''')
        z.writestr('xl/_rels/workbook.xml.rels','''<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/><Relationship Id="rId2" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/></Relationships>''')
        z.writestr('xl/workbook.xml','''<?xml version="1.0" encoding="UTF-8" standalone="yes"?><workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="سمشف" sheetId="1" r:id="rId1"/></sheets></workbook>''')
        z.writestr('xl/styles.xml','''<?xml version="1.0" encoding="UTF-8" standalone="yes"?><styleSheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"><fonts count="2"><font><sz val="11"/><name val="Tahoma"/></font><font><b/><sz val="11"/><color rgb="FFFFFFFF"/><name val="Tahoma"/></font></fonts><fills count="3"><fill><patternFill patternType="none"/></fill><fill><patternFill patternType="gray125"/></fill><fill><patternFill patternType="solid"><fgColor rgb="FF7B3D4D"/><bgColor indexed="64"/></patternFill></fill></fills><borders count="1"><border><left/><right/><top/><bottom/><diagonal/></border></borders><cellStyleXfs count="1"><xf numFmtId="0" fontId="0" fillId="0" borderId="0"/></cellStyleXfs><cellXfs count="2"><xf numFmtId="0" fontId="0" fillId="0" borderId="0" xfId="0"/><xf numFmtId="0" fontId="1" fillId="2" borderId="0" xfId="0" applyFont="1" applyFill="1"/></cellXfs></styleSheet>''')
        all_rows=[[title],list(headings),*map(list,rows)]
        parts=['<?xml version="1.0" encoding="UTF-8" standalone="yes"?><worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"><sheetViews><sheetView rightToLeft="1" workbookViewId="0"><pane ySplit="2" topLeftCell="A3" activePane="bottomLeft" state="frozen"/></sheetView></sheetViews><cols>']
        for i in range(1,len(headings)+1):parts.append(f'<col min="{i}" max="{i}" width="{33 if i==1 else 21}" customWidth="1"/>')
        parts.append('</cols><sheetData>')
        for ri,row in enumerate(all_rows,1):
            parts.append(f'<row r="{ri}">')
            for ci,value in enumerate(row,1):
                ref=f'{_col(ci)}{ri}';style=' s="1"' if ri<=2 else ''
                if isinstance(value,(int,float)) and not isinstance(value,bool):
                    parts.append(f'<c r="{ref}"{style}><v>{value}</v></c>')
                else:
                    # inlineStr prevents spreadsheet-formula injection from user-entered strings
                    txt=escape(str(value if value is not None else ''))
                    parts.append(f'<c r="{ref}" t="inlineStr"{style}><is><t xml:space="preserve">{txt}</t></is></c>')
            parts.append('</row>')
        parts.append('</sheetData></worksheet>')
        z.writestr('xl/worksheets/sheet1.xml',''.join(parts))
    response=HttpResponse(output.getvalue(),content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet')
    response['Content-Disposition']=f'attachment; filename="{filename}"'
    response['Cache-Control']='no-store'
    return response