feat: add write_styled_excel utility for styled Excel exports #83

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/utils/table.py

@@ -2,6 +2,7 @@ import os
 import uuid
 
 import polars as pl
+import xlsxwriter
 from dash import no_update
 from polars import selectors as cs
 from unidecode import unidecode
@@ -557,3 +558,32 @@ def invert_columns(columns):
 
 
 COLUMNS = schema.names()
+
+_EXCEL_MIN_COLUMN_WIDTH = 132  # ≈ 3.5 cm à 96 DPI
+_EXCEL_HEADER_FORMAT = {
+    "bold": True,
+    "bg_color": "#b33821",
+    "font_color": "white",
+}
+_EXCEL_COLUMN_WIDTHS = {
+    "objet": 350,
+    "acheteur_nom": 250,
+    "titulaire_nom": 250,
+    "acheteur_id": 160,
+}
+
+
+def write_styled_excel(df: pl.DataFrame, buffer, worksheet: str = "DECP") -> None:
+    col_widths = {
+        col: max(_EXCEL_MIN_COLUMN_WIDTH, _EXCEL_COLUMN_WIDTHS.get(col, 0))
+        for col in df.columns
+    }
+    wb = xlsxwriter.Workbook(buffer, {"default_format_properties": {"text_wrap": True}})
+    ws = wb.add_worksheet(worksheet)
+    df.write_excel(
+        workbook=wb,
+        worksheet=ws,
+        header_format=_EXCEL_HEADER_FORMAT,
+        column_widths=col_widths,
+    )
+    wb.close()

tests/test_excel.py

@@ -0,0 +1,54 @@
+import io
+
+import openpyxl
+import polars as pl
+
+from src.utils.table import write_styled_excel
+
+
+def test_write_styled_excel_header_bold_and_color():
+    df = pl.DataFrame({"objet": ["marché A"], "montant": [1000.0]})
+    buf = io.BytesIO()
+    write_styled_excel(df, buf)
+    buf.seek(0)
+    wb = openpyxl.load_workbook(buf)
+    ws = wb.active
+    cell = ws.cell(row=1, column=1)
+    assert cell.font.bold is True
+    assert cell.fill.fgColor.rgb == "FFB33821"
+    assert cell.font.color.rgb == "FFFFFFFF"
+
+
+def test_write_styled_excel_data_cell_text_wrap():
+    df = pl.DataFrame({"objet": ["marché A"]})
+    buf = io.BytesIO()
+    write_styled_excel(df, buf)
+    buf.seek(0)
+    wb = openpyxl.load_workbook(buf)
+    ws = wb.active
+    cell = ws.cell(row=2, column=1)
+    assert cell.alignment.wrap_text is True
+
+
+def test_write_styled_excel_known_column_wider_than_minimum():
+    # "objet" a une largeur explicite (350px) > minimum (132px)
+    # "autre" n'a pas de largeur explicite → reçoit le minimum
+    df = pl.DataFrame({"autre": ["x"], "objet": ["y"]})
+    buf = io.BytesIO()
+    write_styled_excel(df, buf)
+    buf.seek(0)
+    wb = openpyxl.load_workbook(buf)
+    ws = wb.active
+    width_autre = ws.column_dimensions["A"].width  # colonne 1 = "autre"
+    width_objet = ws.column_dimensions["B"].width  # colonne 2 = "objet"
+    assert width_autre > 0
+    assert width_objet > width_autre
+
+
+def test_write_styled_excel_custom_worksheet_name():
+    df = pl.DataFrame({"col": ["val"]})
+    buf = io.BytesIO()
+    write_styled_excel(df, buf, worksheet="2025")
+    buf.seek(0)
+    wb = openpyxl.load_workbook(buf)
+    assert "2025" in wb.sheetnames