ex4.py

months = [
        {"days": 31, "name": "janvier"},
        {"days": 29, "name": "fevrier"},
        {"days": 31, "name": "mars"},
        {"days": 30, "name": "avril"},
        {"days": 31, "name": "mai"},
        {"days": 30, "name": "juin"},
        {"days": 31, "name": "juillet"},
        {"days": 31, "name": "aout"},
        {"days": 30, "name": "septembre"},
        {"days": 31, "name": "octobre"},
        {"days": 30, "name": "novembre"},
        {"days": 31, "name": "decembre"}
        ]

days = [
        "lundi",
        "mardi",
        "mercredi",
        "jeudi",
        "vendredi",
        "samedi",
        "dimanche"
        ]

def french_date(day, month):
    days_in_year = 0
    for imonth, data in enumerate(months):
        if imonth+1 < month:
            days_in_year += data["days"]
        else:
            break

    days_in_year += day
    weekday = days[(days_in_year + 2 - 1) % 7]
    return f"{weekday} {day} {months[month-1]['name']} 2020"

def date_format(date, dformat = "dd/mm"):
    if dformat == "dd/mm":
        day = int(date[:2])
        month = int(date[3:])
    elif dformat == "mm/dd":
        day = int(date[3:])
        month = int(date[:2])
    else:
        print(f"Format non supporte {dformat}")
        return ""

    if month > 12 or month < 1:
        print(f"Mois non valide: {month}")
        return ""
    if day > months[month-1]["days"]:
        print(f"Jour non valide: {day} pour le mois de {months[month-1]['name']}")
        return ""

    return french_date(day, month)