app.py

"""
Roommate Allocation System — Streamlit UI
Uses the Gale-Shapley algorithm (Python implementation).
For the original C + MySQL version, see:
https://github.com/Harshwardhan-Deshmukh03/Roommate-allocation-using-Gale-Shapley-Algorithm.git
"""

import streamlit as st
import pandas as pd
import os, json

from db import (
    get_all_students, get_all_rooms, get_all_allocations,
    save_all_students, save_all_rooms, save_allocations,
    clear_all_students, clear_all_rooms, clear_allocations,
    add_student, delete_student, add_room, delete_room,
    import_students_from_csv, import_rooms_from_csv,
    get_student_count, get_room_count,
)
from gale_shapley import run_full_allocation

# ── Page Config ───────────────────────────────────────────────────────────────
st.set_page_config(
    page_title="Roommate Allocation · Gale-Shapley",
    page_icon="🏠",
    layout="wide",
    initial_sidebar_state="expanded",
)

# ── Custom CSS ────────────────────────────────────────────────────────────────
st.markdown("""
<style>
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');
:root {
    --accent: #6C63FF; --accent2: #00D2FF; --bg: #0E1117;
    --card: #161B22; --card2: #1A1D29; --text: #E0E0E0;
    --success: #00E676; --warn: #FFD600; --danger: #FF5252;
}
html, body, [class*="css"] { font-family: 'Inter', sans-serif; }

/* Hero banner */
.hero {
    background: linear-gradient(135deg, #6C63FF 0%, #00D2FF 100%);
    border-radius: 16px; padding: 2.5rem 2rem; margin-bottom: 1.5rem;
    text-align: center; position: relative; overflow: hidden;
}
.hero::before {
    content: ''; position: absolute; inset: 0;
    background: radial-gradient(circle at 30% 50%, rgba(255,255,255,.12) 0%, transparent 60%);
}
.hero h1 { color: #fff; font-size: 2.2rem; font-weight: 800; margin: 0; position: relative; }
.hero p  { color: rgba(255,255,255,.85); font-size: 1rem; margin: .5rem 0 0; position: relative; }

/* Stat cards */
.stat-row { display: flex; gap: 1rem; margin-bottom: 1.5rem; flex-wrap: wrap; }
.stat-card {
    flex: 1; min-width: 160px; background: var(--card); border-radius: 14px;
    padding: 1.4rem; text-align: center; border: 1px solid rgba(108,99,255,.25);
    transition: transform .2s, box-shadow .2s;
}
.stat-card:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(108,99,255,.2); }
.stat-card .num { font-size: 2rem; font-weight: 700; background: linear-gradient(135deg,#6C63FF,#00D2FF);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.stat-card .lbl { color: #9CA3AF; font-size: .85rem; margin-top: .3rem; }

/* Section headers */
.sec-hdr { font-size: 1.35rem; font-weight: 700; margin: 1.5rem 0 .8rem;
    padding-left: .6rem; border-left: 4px solid var(--accent); }

/* Info banner */
.info-banner {
    background: linear-gradient(135deg, rgba(108,99,255,.12), rgba(0,210,255,.08));
    border: 1px solid rgba(108,99,255,.3); border-radius: 12px;
    padding: 1rem 1.2rem; margin: 1rem 0; font-size: .9rem; color: var(--text);
}

/* Footer */
.footer { text-align: center; padding: 2rem 0 1rem; color: #6B7280; font-size: .82rem; }
.footer a { color: var(--accent); text-decoration: none; }
.footer a:hover { text-decoration: underline; }

/* Table tweaks */
.stDataFrame { border-radius: 12px; overflow: hidden; }
</style>
""", unsafe_allow_html=True)

# ── Sidebar ───────────────────────────────────────────────────────────────────
with st.sidebar:
    st.markdown("## 🧭 Navigation")
    page = st.radio(
        "Go to",
        ["🏠 Dashboard", "👥 Manage Students", "🚪 Manage Rooms",
         "📂 CSV Import", "⚙️ Run Allocation", "📊 Results"],
        label_visibility="collapsed",
    )
    st.markdown("---")
    st.markdown(
        '<div class="info-banner">'
        '<b>🐍 Python + Streamlit Edition</b><br>'
        'File-system storage (no MySQL needed).<br><br>'
        'For the <b>C + MySQL</b> version:<br>'
        '<a href="https://github.com/Harshwardhan-Deshmukh03/Roommate-allocation-using-Gale-Shapley-Algorithm.git" '
        'target="_blank">View on GitHub ↗</a></div>',
        unsafe_allow_html=True,
    )

# ── Helper ────────────────────────────────────────────────────────────────────
def stat_cards(items):
    cols = st.columns(len(items))
    for col, (num, lbl) in zip(cols, items):
        col.markdown(
            f'<div class="stat-card"><div class="num">{num}</div>'
            f'<div class="lbl">{lbl}</div></div>',
            unsafe_allow_html=True,
        )

# ══════════════════════════════════════════════════════════════════════════════
#  PAGES
# ══════════════════════════════════════════════════════════════════════════════

# ── Dashboard ─────────────────────────────────────────────────────────────────
if page == "🏠 Dashboard":
    st.markdown(
        '<div class="hero"><h1>🏠 Roommate Allocation System</h1>'
        '<p>Gale-Shapley Stable-Matching Algorithm · Python &amp; Streamlit</p></div>',
        unsafe_allow_html=True,
    )
    n_stu = get_student_count()
    n_rm  = get_room_count()
    allocs = get_all_allocations()
    stat_cards([
        (n_stu, "Students"), (n_rm, "Rooms"),
        (n_stu // 2 if n_stu else 0, "Possible Pairs"),
        (len(allocs), "Allocations"),
    ])

    st.markdown('<div class="sec-hdr">How It Works</div>', unsafe_allow_html=True)
    c1, c2 = st.columns(2)
    with c1:
        st.markdown("""
**Stage 1 — Roommate Matching**
1. Each student submits an ordered preference list of roommates.
2. The Gale-Shapley algorithm pairs students into **stable matches**
   (no two students would rather swap partners).
""")
    with c2:
        st.markdown("""
**Stage 2 — Room Allocation**
1. Pairs are ranked by the **higher CGPA** in each pair.
2. Ranked pairs select rooms via Gale-Shapley, so top performers
   get priority for their preferred rooms.
""")

    st.markdown('<div class="sec-hdr">Quick Start</div>', unsafe_allow_html=True)
    st.markdown("""
1. **Add Students** — manually or via CSV upload.
2. **Add Rooms** — manually or via CSV upload.
3. **Run Allocation** — click one button to get stable assignments.
4. **View Results** — see the final roommate + room table & charts.
""")

    st.markdown(
        '<div class="footer">Built with Python &amp; Streamlit · '
        'Algorithm by Gale &amp; Shapley (1962) · '
        '<a href="https://github.com/Harshwardhan-Deshmukh03/Roommate-allocation-using-Gale-Shapley-Algorithm.git" '
        'target="_blank">Original C + MySQL version</a></div>',
        unsafe_allow_html=True,
    )

# ── Manage Students ──────────────────────────────────────────────────────────
elif page == "👥 Manage Students":
    st.markdown('<div class="sec-hdr">👥 Manage Students</div>', unsafe_allow_html=True)

    students = get_all_students()
    stat_cards([(len(students), "Total Students")])

    # Show current students
    if students:
        df = pd.DataFrame(students)
        df["pref_roommate"] = df["pref_roommate"].apply(lambda x: " ".join(map(str, x)))
        df["pref_room"]     = df["pref_room"].apply(lambda x: " ".join(map(str, x)))
        st.dataframe(df, use_container_width=True, hide_index=True)
    else:
        st.info("No students yet. Add below or import via CSV.")

    st.markdown("---")
    st.markdown("#### ➕ Add a Student")
    with st.form("add_student", clear_on_submit=True):
        ac1, ac2, ac3 = st.columns(3)
        sid  = ac1.number_input("Student ID", min_value=0, step=1)
        name = ac2.text_input("Name")
        cgpa = ac3.number_input("CGPA", min_value=0.0, max_value=10.0, step=0.1)
        pref_r = st.text_input("Roommate Preferences (space-separated IDs)", placeholder="5 6 7 8 9 ...")
        pref_rm = st.text_input("Room Preferences (space-separated room IDs)", placeholder="0 1 2 3 4 ...")
        submitted = st.form_submit_button("Add Student", type="primary")
        if submitted:
            if not name.strip():
                st.error("Name cannot be empty.")
            else:
                try:
                    pr = [int(x) for x in pref_r.strip().split()] if pref_r.strip() else []
                    pm = [int(x) for x in pref_rm.strip().split()] if pref_rm.strip() else []
                    ok = add_student({"id": int(sid), "name": name.strip(), "cgpa": float(cgpa),
                                      "pref_roommate": pr, "pref_room": pm})
                    if ok:
                        st.success(f"✅ Added **{name}** (ID {sid})")
                        st.rerun()
                    else:
                        st.error(f"Student ID {sid} already exists.")
                except ValueError:
                    st.error("Preferences must be space-separated integers.")

    # Delete
    if students:
        st.markdown("#### 🗑️ Remove a Student")
        dc1, dc2 = st.columns([3, 1])
        del_id = dc1.selectbox("Select student to remove",
                               [(s["id"], s["name"]) for s in students],
                               format_func=lambda x: f"ID {x[0]} — {x[1]}")
        if dc2.button("Delete", type="secondary"):
            delete_student(del_id[0])
            st.success(f"Removed student ID {del_id[0]}")
            st.rerun()

        if st.button("🗑️ Clear ALL Students", type="secondary"):
            clear_all_students()
            st.warning("All students cleared.")
            st.rerun()

# ── Manage Rooms ──────────────────────────────────────────────────────────────
elif page == "🚪 Manage Rooms":
    st.markdown('<div class="sec-hdr">🚪 Manage Rooms</div>', unsafe_allow_html=True)

    rooms = get_all_rooms()
    stat_cards([(len(rooms), "Total Rooms")])

    if rooms:
        st.dataframe(pd.DataFrame(rooms), use_container_width=True, hide_index=True)
    else:
        st.info("No rooms yet. Add below or import via CSV.")

    st.markdown("---")
    st.markdown("#### ➕ Add a Room")
    with st.form("add_room", clear_on_submit=True):
        rc1, rc2 = st.columns(2)
        rid  = rc1.number_input("Room ID", min_value=0, step=1)
        rnum = rc2.text_input("Room Number", placeholder="e.g. A101")
        if st.form_submit_button("Add Room", type="primary"):
            if not rnum.strip():
                st.error("Room number cannot be empty.")
            else:
                ok = add_room({"room_id": int(rid), "room_number": rnum.strip()})
                if ok:
                    st.success(f"✅ Added room **{rnum}** (ID {rid})")
                    st.rerun()
                else:
                    st.error(f"Room ID {rid} already exists.")

    if rooms:
        st.markdown("#### 🗑️ Remove a Room")
        drc1, drc2 = st.columns([3, 1])
        del_rid = drc1.selectbox("Select room to remove",
                                 [(r["room_id"], r["room_number"]) for r in rooms],
                                 format_func=lambda x: f"ID {x[0]} — {x[1]}")
        if drc2.button("Delete", type="secondary"):
            delete_room(del_rid[0])
            st.success(f"Removed room ID {del_rid[0]}")
            st.rerun()

        if st.button("🗑️ Clear ALL Rooms", type="secondary"):
            clear_all_rooms()
            st.warning("All rooms cleared.")
            st.rerun()

# ── CSV Import ────────────────────────────────────────────────────────────────
elif page == "📂 CSV Import":
    st.markdown('<div class="sec-hdr">📂 CSV Import</div>', unsafe_allow_html=True)
    st.markdown(
        '<div class="info-banner">Upload CSV files to bulk-import students and rooms. '
        'This is useful when manual entry is tedious or when the allocation is complex.</div>',
        unsafe_allow_html=True,
    )

    tab1, tab2, tab3 = st.tabs(["📥 Import Students", "📥 Import Rooms", "📄 Sample CSVs"])

    with tab1:
        st.markdown("**Expected columns:** `id, name, cgpa, pref_roommate, pref_room`")
        st.caption("Preferences are space-separated integer IDs.")
        f = st.file_uploader("Upload Students CSV", type=["csv"], key="stu_csv")
        if f:
            content = f.getvalue().decode("utf-8")
            st.markdown("**Preview:**")
            st.dataframe(pd.read_csv(f), use_container_width=True, hide_index=True)
            f.seek(0)
            if st.button("✅ Import Students", type="primary"):
                cnt, errs = import_students_from_csv(content)
                if errs:
                    for e in errs:
                        st.error(e)
                st.success(f"Imported **{cnt}** students.")
                st.rerun()

    with tab2:
        st.markdown("**Expected columns:** `room_id, room_number`")
        f2 = st.file_uploader("Upload Rooms CSV", type=["csv"], key="room_csv")
        if f2:
            content2 = f2.getvalue().decode("utf-8")
            st.markdown("**Preview:**")
            st.dataframe(pd.read_csv(f2), use_container_width=True, hide_index=True)
            f2.seek(0)
            if st.button("✅ Import Rooms", type="primary"):
                cnt2, errs2 = import_rooms_from_csv(content2)
                if errs2:
                    for e in errs2:
                        st.error(e)
                st.success(f"Imported **{cnt2}** rooms.")
                st.rerun()

    with tab3:
        st.markdown("#### Sample CSV Files")
        st.markdown("Download these to understand the expected format, then modify and re-upload.")
        sample_dir = os.path.join(os.path.dirname(__file__), "sample_csv")
        for fname in sorted(os.listdir(sample_dir)):
            fpath = os.path.join(sample_dir, fname)
            with open(fpath, "r") as sf:
                st.download_button(f"⬇️  {fname}", sf.read(), file_name=fname, mime="text/csv")
            with open(fpath, "r") as sf:
                st.markdown(f"**`{fname}` preview:**")
                st.code(sf.read(), language="csv")

# ── Run Allocation ────────────────────────────────────────────────────────────
elif page == "⚙️ Run Allocation":
    st.markdown('<div class="sec-hdr">⚙️ Run Allocation</div>', unsafe_allow_html=True)

    students = get_all_students()
    rooms    = get_all_rooms()
    n_stu = len(students)
    n_rm  = len(rooms)

    stat_cards([(n_stu, "Students"), (n_rm, "Rooms"), (n_stu // 2, "Pairs Needed")])

    # Validation
    issues = []
    if n_stu < 2:
        issues.append("Need at least 2 students.")
    if n_stu % 2 != 0:
        issues.append("Number of students must be even.")
    if n_rm < n_stu // 2:
        issues.append(f"Need at least {n_stu // 2} rooms (have {n_rm}).")

    if issues:
        for iss in issues:
            st.error(f"❌ {iss}")
        st.info("Fix the above issues before running the algorithm.")
    else:
        st.success("✅ All checks passed — ready to allocate!")
        st.markdown(
            '<div class="info-banner">'
            '<b>Stage 1:</b> Gale-Shapley matches students into roommate pairs.<br>'
            '<b>Stage 2:</b> Pairs ranked by CGPA select rooms via Gale-Shapley.</div>',
            unsafe_allow_html=True,
        )

        if st.button("🚀  Run Gale-Shapley Allocation", type="primary", use_container_width=True):
            with st.spinner("Running Gale-Shapley algorithm..."):
                try:
                    allocs = run_full_allocation(students, rooms)
                    save_allocations(allocs)
                    st.success(f"🎉 Allocation complete — **{len(allocs)} pairs** assigned!")
                    st.balloons()

                    df = pd.DataFrame(allocs)
                    display_cols = ["roommate1_name", "roommate1_cgpa",
                                    "roommate2_name", "roommate2_cgpa",
                                    "room_number", "pair_max_cgpa"]
                    st.dataframe(df[display_cols], use_container_width=True, hide_index=True)
                except Exception as e:
                    st.error(f"Allocation failed: {e}")
                    st.info("Try importing data via CSV if manual entry is causing issues.")

# ── Results ───────────────────────────────────────────────────────────────────
elif page == "📊 Results":
    st.markdown('<div class="sec-hdr">📊 Allocation Results</div>', unsafe_allow_html=True)

    allocs = get_all_allocations()
    if not allocs:
        st.info("No allocation results yet. Go to **⚙️ Run Allocation** first.")
    else:
        df = pd.DataFrame(allocs)

        stat_cards([
            (len(df), "Pairs Allocated"),
            (f"{df['pair_max_cgpa'].mean():.2f}", "Avg Pair CGPA"),
            (df["room_number"].nunique(), "Rooms Used"),
        ])

        # Main table
        st.markdown("#### 📋 Final Allocation Table")
        display = df[["roommate1_name", "roommate1_cgpa",
                       "roommate2_name", "roommate2_cgpa",
                       "room_number", "pair_max_cgpa"]].copy()
        display.columns = ["Roommate 1", "CGPA 1", "Roommate 2", "CGPA 2", "Room", "Pair CGPA"]
        st.dataframe(display, use_container_width=True, hide_index=True)

        # Download
        csv_out = display.to_csv(index=False)
        st.download_button("⬇️  Download Results CSV", csv_out,
                           file_name="allocation_results.csv", mime="text/csv")

        # Charts
        st.markdown("#### 📈 CGPA Distribution")
        import plotly.express as px

        fig = px.bar(
            display, x="Room", y="Pair CGPA",
            color="Pair CGPA",
            color_continuous_scale=["#6C63FF", "#00D2FF"],
            title="Pair CGPA by Room Assignment",
        )
        fig.update_layout(
            plot_bgcolor="rgba(0,0,0,0)", paper_bgcolor="rgba(0,0,0,0)",
            font_color="#E0E0E0", title_font_size=16,
        )
        st.plotly_chart(fig, use_container_width=True)

        # Roommate comparison
        st.markdown("#### 🤝 Roommate CGPA Comparison")
        comp = pd.DataFrame({
            "Room": display["Room"],
            "Roommate 1": display["CGPA 1"],
            "Roommate 2": display["CGPA 2"],
        })
        fig2 = px.bar(
            comp.melt(id_vars="Room", var_name="Roommate", value_name="CGPA"),
            x="Room", y="CGPA", color="Roommate", barmode="group",
            color_discrete_sequence=["#6C63FF", "#00D2FF"],
            title="CGPA Comparison per Room",
        )
        fig2.update_layout(
            plot_bgcolor="rgba(0,0,0,0)", paper_bgcolor="rgba(0,0,0,0)",
            font_color="#E0E0E0", title_font_size=16,
        )
        st.plotly_chart(fig2, use_container_width=True)

        if st.button("🗑️ Clear Results", type="secondary"):
            clear_allocations()
            st.warning("Results cleared.")
            st.rerun()

    st.markdown(
        '<div class="footer">Built with <b>Python &amp; Streamlit</b> · '
        'For the <b>C + MySQL</b> version, visit '
        '<a href="https://github.com/Harshwardhan-Deshmukh03/Roommate-allocation-using-Gale-Shapley-Algorithm.git" '
        'target="_blank">GitHub ↗</a></div>',
        unsafe_allow_html=True,
    )