# phase/Teacher_view/classmanage.py
import os
import streamlit as st

from utils import db as dbapi
import utils.api as api  # backend Space client

# When DISABLE_DB=1 (default), skip direct MySQL and use backend APIs
USE_LOCAL_DB = os.getenv("DISABLE_DB", "1") != "1"


def _metric_card(label: str, value: str, caption: str = ""):
    st.markdown(
        f"""
        <div class="metric-card">
          <div class="metric-value">{value}</div>
          <div class="metric-label">{label}</div>
          <div class="metric-caption">{caption}</div>
        </div>
        """,
        unsafe_allow_html=True,
    )


def _prefer_db(db_name: str, api_func, default, *args, **kwargs):
    """
    Try local DB function if enabled & present; else call backend API; else return default.
    """
    if USE_LOCAL_DB and hasattr(dbapi, db_name):
        try:
            return getattr(dbapi, db_name)(*args, **kwargs)
        except Exception as e:
            st.warning(f"DB call {db_name} failed; falling back to backend. ({e})")
    try:
        return api_func(*args, **kwargs)
    except Exception as e:
        st.error(f"Backend call failed: {e}")
        return default


def show_page():
    user = st.session_state.user
    teacher_id = user["user_id"]

    st.title("📚 Classroom Management")
    st.caption("Manage all your classrooms and students")

    # -------- Create Classroom --------
    with st.expander("➕ Create Classroom", expanded=False):
        new_name = st.text_input("Classroom Name", key="new_classroom_name")
        if st.button("Create Classroom"):
            name = new_name.strip()
            if not name:
                st.error("Enter a real name, not whitespace.")
            else:
                out = _prefer_db(
                    "create_class",
                    lambda tid, n: api.create_class(tid, n),
                    None,
                    teacher_id,  # positional arg
                    name,        # positional arg
                )
                if out:
                    st.session_state.selected_class_id = out.get("class_id") or out.get("id")
                    st.success(f'Classroom "{name}" created with code: {out.get("code","—")}')
                    st.rerun()
                else:
                    st.error("Could not create classroom (no response).")

    # -------- Load classes for this teacher --------
    classes = _prefer_db(
        "list_classes_by_teacher",
        lambda tid: api.list_classes_by_teacher(tid),
        [],
        teacher_id,  # positional
    )

    if not classes:
        st.info("No classrooms yet. Create one above, then share the code.")
        return

    # Picker
    st.subheader("Your Classrooms")
    options = {f"{c.get('name','(unnamed)')} (Code: {c.get('code','')})": c for c in classes}
    selected_label = st.selectbox("Select a classroom", list(options.keys()))
    selected = options[selected_label]
    class_id = selected.get("class_id") or selected.get("id")

    st.markdown("---")
    st.header(selected.get("name", "Classroom"))

    # -------- Code stripe --------
    st.subheader("Class Code")
    c1, c2, c3 = st.columns([3, 1, 1])
    with c1:
        st.markdown(f"**`{selected.get('code', 'UNKNOWN')}`**")
    with c2:
        if st.button("📋 Copy Code"):
            st.toast("Code is shown above. Copy it.")
    with c3:
        st.button("🗑️ Delete Class", disabled=True, help="Soft-delete coming later")

    # -------- Tabs --------
    tab_students, tab_content, tab_analytics = st.tabs(["👥 Students", "📘 Content", "📊 Analytics"])

    # ============== Students tab ==============
    with tab_students:
        q = st.text_input("Search students by name or email", "")
        roster = _prefer_db(
            "list_students_in_class",
            lambda cid: api.list_students_in_class(cid),
            [],
            class_id,  # positional
        )

        # simple filter
        if q.strip():
            ql = q.lower()
            roster = [r for r in roster if ql in (r.get("name","").lower()) or ql in (r.get("email","").lower())]

        st.caption(f"{len(roster)} Students Found")

        if not roster:
            st.info("No students in this class yet.")
        else:
            for s in roster:
                st.subheader(f"👤 {s.get('name','(unknown)')}")
                st.caption(s.get("email","—"))
                joined = s.get("joined_at") or s.get("created_at")
                st.caption(f"📅 Joined: {str(joined)[:10] if joined else '—'}")
                st.progress(0.0)  # placeholder bar
                cols = st.columns(3)
                level_slug = (s.get("level_slug") or s.get("level") or "beginner")
                try:
                    level_label = level_slug.capitalize() if isinstance(level_slug, str) else str(level_slug)
                except Exception:
                    level_label = "—"
                cols[0].metric("⭐ Level", level_label)
                cols[1].metric("📊 Avg Score", "—")
                cols[2].metric("🔥 Streak", "—")
                st.markdown("---")

    # ============== Content tab ==============
    with tab_content:
        counts = _prefer_db(
            "class_content_counts",
            lambda cid: api.class_content_counts(cid),
            {"lessons": 0, "quizzes": 0},
            class_id,  # positional
        )
        left, right = st.columns(2)
        with left:
            _metric_card("📖 Custom Lessons", str(counts.get("lessons", 0)), "Lessons created for this classroom")
        with right:
            _metric_card("🏆 Custom Quizzes", str(counts.get("quizzes", 0)), "Quizzes created for this classroom")

        assigs = _prefer_db(
            "list_class_assignments",
            lambda cid: api.list_class_assignments(cid),
            [],
            class_id,  # positional
        )
        if assigs:
            st.markdown("#### Assigned items")
            for a in assigs:
                has_quiz = " + Quiz" if a.get("quiz_id") else ""
                st.markdown(f"- **{a.get('title','Untitled')}** · {a.get('subject','—')} · {a.get('level','—')}{has_quiz}")

    # ============== Analytics tab ==============
    with tab_analytics:
        stats = _prefer_db(
            "class_analytics",
            lambda cid: api.class_analytics(cid),
            {"class_avg": 0.0, "total_xp": 0, "lessons_completed": 0},
            class_id,  # positional
        )

        class_avg_pct = round(float(stats.get("class_avg", 0)) * 100) if stats.get("class_avg") is not None else 0
        total_xp = stats.get("total_xp", 0)
        lessons_completed = stats.get("lessons_completed", 0)

        g1, g2, g3 = st.columns(3)
        with g1:
            _metric_card("📊 Class Average", f"{class_avg_pct}%", "Average quiz performance")
        with g2:
            _metric_card("🪙 Total XP", f"{total_xp}", "Combined XP earned")
        with g3:
            _metric_card("📘 Lessons Completed", f"{lessons_completed}", "Total lessons completed")