app.py

import streamlit as st

# CSS inchangé
st.markdown("""
    <style>
    .block-container {padding-top: 1.2rem; padding-bottom: 1rem;}
    h1, h2, h3 {margin: 0.4rem 0;}
    .stExpander {margin-bottom: 0.6rem;}
    div.row-widget.stHorizontal {gap: 0.6rem;}
    .stNumberInput > div > div > input {text-align: center;}
    section.main > div {padding: 1rem 1.2rem;}
    </style>
""", unsafe_allow_html=True)

st.set_page_config(page_title="Bayes – Calcul rapide", layout="wide")

st.title("🧠 Bayes – Calcul interactif")
st.caption("P(A|B) = [P(B|A) × P(A)] / P(B)")

with st.expander("Rappel formule", expanded=False):
    st.markdown("P(B) = P(B|A)×P(A) + P(B|¬A)×P(¬A)")

# ─── Mode + select ────────────────────────────────────────────────────────
col_mode, col_ex = st.columns([40, 60])
with col_mode:
    mode_ds = st.toggle("Mode Data Science (Recall/Precision)", value=False)

if mode_ds:
    lbl = {
        "prev": "Prévalence (Classe +)",
        "recall": "Recall (Sensibilité)",
        "spe": "Spécificité (TNR)",
        "post": "Précision (VPP)",
    }
else:
    lbl = {
        "prev": "Prior P(A)",
        "recall": "Sensibilité P(+|A)",
        "spe": "Spécificité P(-|¬A)",
        "post": "Postérieur P(A|+)",
    }

with col_ex:
    exemples = [
        "Manuel",
        "Cancer dépistage ~0.8%",
        "Fraude CB ~0.1%",
        "Grossesse ~4–5%",
        "ADN culpabilité ~0.001%"
    ]
    choix = st.selectbox("Exemple", exemples, index=0, key="exemple_select")

# Détection changement + suffix pour clés dynamiques
if "prev_choix" not in st.session_state:
    st.session_state.prev_choix = "INIT"

exemple_changed = choix != st.session_state.prev_choix
key_suffix = f"_{choix.replace(' ', '_')}" if exemple_changed else ""

# Mise à jour
st.session_state.prev_choix = choix

# Defaults
defaults = {
    "Cancer dépistage ~0.8%":     (0.8,   85.0,  92.0),
    "Fraude CB ~0.1%":            (0.1,   92.0,  99.85),
    "Grossesse ~4–5%":            (4.5,   99.0,  99.5),
    "ADN culpabilité ~0.001%":    (0.001, 99.9,  99.99),
}.get(choix, (5.0, 90.0, 95.0))

# ─── Inputs avec clés dynamiques quand changement ─────────────────────────
c1, c2, c3, c4 = st.columns(4, gap="small")

with c1:
    st.caption(f"{lbl['prev']} (%)")
    prev = st.number_input(
        label            = lbl['prev'],
        min_value        = 0.0,
        max_value        = 100.0,
        value            = float(defaults[0]),
        step             = 0.01,
        key              = f"prev{key_suffix}",
        label_visibility = "collapsed"
    )

with c2:
    st.caption(f"{lbl['recall']} (%)")
    recall = st.number_input(
        label            = lbl['recall'],
        min_value        = 0.0,
        max_value        = 100.0,
        value            = float(defaults[1]),
        step             = 0.1,
        key              = f"rec{key_suffix}",
        label_visibility = "collapsed"
    )

with c3:
    st.caption(f"{lbl['spe']} (%)")
    speci = st.number_input(
        label            = lbl['spe'],
        min_value        = 0.0,
        max_value        = 100.0,
        value            = float(defaults[2]),
        step             = 0.1,
        key              = f"spe{key_suffix}",
        label_visibility = "collapsed"
    )

with c4:
    st.caption(f"{lbl['post']} (%)")
    post = st.number_input(
        label            = lbl['post'],
        min_value        = 0.0,
        max_value        = 100.0,
        value            = 50.0,
        step             = 0.1,
        key              = f"post{key_suffix}",
        label_visibility = "collapsed"
    )

# ─── Checkboxes (inchangées, mais on peut les reset si tu veux) ───────────
st.write("")  
st.subheader("Calculer :", divider=False)

cols = st.columns(4, gap="small")
calc_prev   = cols[0].checkbox(lbl["prev"],   key="c_prev")
calc_recall = cols[1].checkbox(lbl["recall"], key="c_rec")
calc_speci  = cols[2].checkbox(lbl["spe"],    key="c_spe")
calc_post   = cols[3].checkbox(lbl["post"],   value=True, key="c_post")

# Bouton Calculer (inchangé)
if st.button("Calculer", type="primary", use_container_width=True):
    p   = prev   / 100
    se  = recall / 100
    sp  = speci  / 100
    po  = post   / 100

    checked = sum([calc_prev, calc_recall, calc_speci, calc_post])

    if checked != 1:
        st.error("Cocher **exactement une** grandeur à calculer")
    else:
        try:
            res = None
            label = ""

            if calc_post:
                res = (se * p) / (se * p + (1 - sp) * (1 - p))
                label = lbl["post"]
            elif calc_prev:
                res = (po * (1 - sp)) / (se - po * (se - (1 - sp)))
                label = lbl["prev"]
            elif calc_recall:
                res = (po * (1 - sp) * (1 - p)) / (p * (1 - po))
                label = lbl["recall"]
            elif calc_speci:
                res = 1 - (se * p * (1 - po)) / (po * (1 - p))
                label = lbl["spe"]

            res_pct = res * 100
            if 0 <= res <= 1:
                st.success(f"**{label} = {res_pct:,.3f} %**")
            else:
                st.warning(f"Résultat : {res_pct:,.2f} %  → paramètres incohérents")

        except ZeroDivisionError:
            st.error("Division par zéro – vérifiez les valeurs extrêmes")
        except Exception as e:
            st.error(f"Erreur : {str(e)}")

# Sources et astuce (inchangés)
with st.expander("Sources et références des exemples", expanded=False):
    st.markdown("... ton contenu ...")

with st.expander("Astuce rapide", expanded=False):
    st.caption("Plus la prévalence est faible → plus la précision chute...")