# phase/Teacher_view/studentlist.py
import os
import streamlit as st
from utils import db as dbapi
import utils.api as api  # backend Space client

# Use local DB only when DISABLE_DB != "1"
USE_LOCAL_DB = os.getenv("DISABLE_DB", "1") != "1"

# ---------- tiny helpers ----------
def _avatar(name: str) -> str:
    return "🧑‍🎓" if hash(name) % 2 else "👩‍🎓"

def _avg_pct_from_row(r) -> int:
    """
    Accepts either:
      - r['avg_pct'] in [0, 100]
      - r['avg_score'] in [0, 1] or [0, 100]
    Returns an int 0..100.
    """
    v = r.get("avg_pct", r.get("avg_score", 0)) or 0
    try:
        f = float(v)
        if f <= 1.0:  # treat as 0..1
            f *= 100.0
        return max(0, min(100, int(round(f))))
    except Exception:
        return 0

def _level_from_xp(total_xp: int) -> int:
    try:
        xp = int(total_xp or 0)
    except Exception:
        xp = 0
    return 1 + xp // 500

def _report_text(r, level, avg_pct):
    return (
        "STUDENT PROGRESS REPORT\n"
        "======================\n"
        f"Student: {r.get('name','')}\n"
        f"Email: {r.get('email','')}\n"
        f"Joined: {str(r.get('joined_at',''))[:10]}\n\n"
        "PROGRESS OVERVIEW\n"
        "-----------------\n"
        f"Lessons Completed: {int(r.get('lessons_completed') or 0)}/{int(r.get('total_assigned_lessons') or 0)}\n"
        f"Average Quiz Score: {avg_pct}%\n"
        f"Total XP: {int(r.get('total_xp') or 0)}\n"
        f"Current Level: {level}\n"
        f"Study Streak: {int(r.get('streak_days') or 0)} days\n"
    )

ROW_CSS = """
<style>
.sm-chip{display:inline-block;padding:4px 10px;border-radius:999px;background:#eef7f1;color:#0b8f5d;font-weight:600;font-size:.80rem;margin-left:8px}
.sm-pill{display:inline-flex;align-items:center;gap:6px;padding:6px 12px;border:1px solid #e6e6e6;border-radius:8px;background:#fff}
.sm-row{border:1px solid #eee;border-radius:12px;padding:16px 16px;margin:10px 0;background:#fff}
.sm-row:hover{box-shadow:0 2px 10px rgba(0,0,0,.04)}
.sm-right{display:flex;gap:16px;align-items:center;justify-content:flex-end}
.sm-metric{min-width:90px;text-align:right}
.sm-metric .label{color:#777;font-size:.75rem}
.sm-metric .value{font-weight:700;font-size:1.1rem}
.sm-name{font-size:1.05rem;font-weight:700}
.sm-sub{color:#6c6c6c;font-size:.85rem}
</style>
"""

# ---------- data access (DB or Backend) ----------
@st.cache_data(show_spinner=False, ttl=30)
def _list_classes_by_teacher(teacher_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "list_classes_by_teacher"):
        return dbapi.list_classes_by_teacher(teacher_id) or []
    try:
        return api.list_classes_by_teacher(teacher_id) or []
    except Exception:
        return []

@st.cache_data(show_spinner=False, ttl=30)
def _get_class(class_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "get_class"):
        return dbapi.get_class(class_id) or {}
    try:
        return api.get_class(class_id) or {}
    except Exception:
        return {}

@st.cache_data(show_spinner=False, ttl=30)
def _class_student_metrics(class_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "class_student_metrics"):
        return dbapi.class_student_metrics(class_id) or []
    try:
        return api.class_student_metrics(class_id) or []
    except Exception:
        return []

@st.cache_data(show_spinner=False, ttl=30)
def _list_assignments_for_student(student_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "list_assignments_for_student"):
        return dbapi.list_assignments_for_student(student_id) or []
    try:
        return api.list_assignments_for_student(student_id) or []
    except Exception:
        return []

# ---------- page ----------
def show_page():
    st.title("🎓 Student Management")
    st.caption("Monitor and manage your students' progress")
    st.markdown(ROW_CSS, unsafe_allow_html=True)

    teacher = st.session_state.get("user")
    if not teacher:
        st.error("Please log in.")
        return
    teacher_id = teacher["user_id"]

    classes = _list_classes_by_teacher(teacher_id)
    if not classes:
        st.info("No classes yet. Create one in Classroom Management.")
        return

    # class selector
    idx = st.selectbox(
        "Choose a class",
        list(range(len(classes))),
        index=0,
        format_func=lambda i: f"{classes[i].get('name','(unnamed)')}"
    )
    selected = classes[idx]
    class_id = selected.get("class_id") or selected.get("id")  # be tolerant to backend naming
    if class_id is None:
        st.error("Selected class is missing an ID.")
        return

    code_row = _get_class(class_id)

    # get students before drawing chips
    rows = _class_student_metrics(class_id)

    # code + student chip row
    chip1, chip2 = st.columns([1, 1])
    with chip1:
        st.markdown(
            f'<div class="sm-chip">Code: {code_row.get("code","")}</div>',
            unsafe_allow_html=True
        )
    with chip2:
        st.markdown(
            f'<div class="sm-chip">👥 {len(rows)} Students</div>',
            unsafe_allow_html=True
        )

    st.markdown("---")

    # search line
    query = st.text_input(
        "Search students by name or email",
        placeholder="Type a name or email..."
    ).strip().lower()

    if query:
        rows = [
            r for r in rows
            if query in (r.get("name","").lower()) or query in (r.get("email","").lower())
        ]

    # student rows
    for r in rows:
        name = r.get("name", "Unknown")
        email = r.get("email", "")
        joined = str(r.get("joined_at", ""))[:10]
        total_xp = int(r.get("total_xp") or 0)
        level = _level_from_xp(total_xp)
        lessons_completed = int(r.get("lessons_completed") or 0)
        total_assigned = int(r.get("total_assigned_lessons") or 0)
        avg_pct = _avg_pct_from_row(r)
        streak = int(r.get("streak_days") or 0)
        student_id = r.get("student_id") or r.get("id")

        with st.container():
            st.markdown('<div class="sm-row">', unsafe_allow_html=True)

            # top bar: avatar + name/email + right metrics
            a, b, c = st.columns([0.7, 4, 3])
            with a:
                st.markdown(f"### {_avatar(name)}")
            with b:
                st.markdown(f'<div class="sm-name">{name}</div>', unsafe_allow_html=True)
                st.markdown(f'<div class="sm-sub">{email}  ·  Joined {joined}</div>', unsafe_allow_html=True)
            with c:
                st.markdown(
                    '<div class="sm-right">'
                    f'<div class="sm-metric"><div class="value">{level}</div><div class="label">Level</div></div>'
                    f'<div class="sm-metric"><div class="value">{avg_pct}%</div><div class="label">Avg Score</div></div>'
                    f'<div class="sm-metric"><div class="value">{streak}</div><div class="label">Streak</div></div>'
                    "</div>",
                    unsafe_allow_html=True
                )

            # progress bar
            st.caption("Overall Progress")
            frac = (lessons_completed / total_assigned) if total_assigned > 0 else 0.0
            st.progress(min(1.0, frac))
            st.caption(f"{lessons_completed}/{total_assigned} lessons")

            # actions row
            d1, d2, spacer = st.columns([2, 1.3, 5])
            with d1:
                with st.popover("👁️ View Details"):
                    if student_id is not None:
                        items = _list_assignments_for_student(int(student_id))
                    else:
                        items = []
                    if items:
                        for it in items[:25]:
                            tag = " + Quiz" if it.get("quiz_id") else ""
                            st.markdown(
                                f"- **{it.get('title','Untitled')}** · {it.get('subject','General')} · "
                                f"{it.get('level','')} {tag} · Status: {it.get('status','unknown')}"
                            )
                    else:
                        st.info("No assignments yet.")
            with d2:
                rep = _report_text(r, level, avg_pct)
                st.download_button(
                    "⬇️ Export",
                    data=rep,
                    file_name=f"{str(name).replace(' ','_')}_report.txt",
                    mime="text/plain",
                    key=f"dl_{student_id or name}"
                )

            st.markdown('</div>', unsafe_allow_html=True)