from io import BytesIO

from openpyxl import Workbook
from openpyxl.utils import get_column_letter
from openpyxl.styles import Font, PatternFill


def build_report_workbook(title, columns, rows):
    workbook = Workbook()
    worksheet = workbook.active
    worksheet.title = "Report"

    headers = [column["label"] for column in columns]
    worksheet.append([title])
    worksheet.merge_cells(
        start_row=1,
        start_column=1,
        end_row=1,
        end_column=max(len(columns), 1),
    )
    worksheet["A1"].font = Font(bold=True, size=14)

    if columns:
        worksheet.append(headers)
        for cell in worksheet[2]:
            cell.font = Font(bold=True)
            cell.fill = PatternFill("solid", fgColor="D9EAF7")

        for row in rows:
            worksheet.append([row.get(column["key"], "") for column in columns])
    else:
        worksheet.append(["No data"])

    for column_index, column_cells in enumerate(worksheet.columns, start=1):
        max_length = max(len(str(cell.value or "")) for cell in column_cells)
        worksheet.column_dimensions[get_column_letter(column_index)].width = min(
            max(max_length + 2, 12),
            60,
        )

    output = BytesIO()
    workbook.save(output)
    return output.getvalue()