# phase/Student_view/teacherlink.py
import os
import streamlit as st
from utils import db as dbapi
import utils.api as api  # <-- backend Space client

USE_LOCAL_DB = os.getenv("DISABLE_DB", "1") != "1"  # DB only when DISABLE_DB=0

def load_css(file_name: str):
    try:
        with open(file_name, "r", encoding="utf-8") as f:
            st.markdown(f"<style>{f.read()}</style>", unsafe_allow_html=True)
    except FileNotFoundError:
        pass

def _progress_0_1(v):
    try:
        f = float(v)
    except Exception:
        return 0.0
    # accept 0..1 or 0..100
    return max(0.0, min(1.0, f if f <= 1.0 else f / 100.0))

# --- Small wrappers to switch between DB and Backend ---

def _join_class_by_code(student_id: int, code: str):
    if USE_LOCAL_DB and hasattr(dbapi, "join_class_by_code"):
        return dbapi.join_class_by_code(student_id, code)
    return api.join_class_by_code(student_id, code)

def _list_classes_for_student(student_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "list_classes_for_student"):
        return dbapi.list_classes_for_student(student_id)
    try:
        return api.list_classes_for_student(student_id)
    except Exception:
        return []

def _class_content_counts(class_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "class_content_counts"):
        return dbapi.class_content_counts(class_id)
    try:
        return api.class_content_counts(class_id)
    except Exception:
        return {"lessons": 0, "quizzes": 0}

def _student_class_progress(student_id: int, class_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "student_class_progress"):
        return dbapi.student_class_progress(student_id, class_id)
    try:
        return api.student_class_progress(student_id, class_id)
    except Exception:
        return {
            "overall_progress": 0,
            "lessons_completed": 0,
            "total_assigned_lessons": 0,
            "avg_score": 0,
        }

def _leave_class(student_id: int, class_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "leave_class"):
        return dbapi.leave_class(student_id, class_id)
    return api.leave_class(student_id, class_id)

def _student_assignments_for_class(student_id: int, class_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "student_assignments_for_class"):
        return dbapi.student_assignments_for_class(student_id, class_id)
    try:
        return api.student_assignments_for_class(student_id, class_id)
    except Exception:
        return []

def _mark_assignment_started(student_id: int, assignment_id: int):
    if USE_LOCAL_DB and hasattr(dbapi, "mark_assignment_started"):
        return dbapi.mark_assignment_started(student_id, assignment_id)
    return api.mark_assignment_started(student_id, assignment_id)

def _set_assignment_progress(student_id: int, assignment_id: int, current_pos: int = 1, progress: float = 0.05):
    # optional nudge so the bar is not 0
    if USE_LOCAL_DB and hasattr(dbapi, "set_assignment_progress"):
        return dbapi.set_assignment_progress(student_id, assignment_id, current_pos, progress)
    return api.set_assignment_progress(student_id, assignment_id, current_pos, progress)


# --- UI ---

def show_code():
    load_css(os.path.join("assets", "styles.css"))

    if "user" not in st.session_state or not st.session_state.user:
        st.error("Please log in as a student.")
        return
    if st.session_state.user["role"] != "Student":
        st.error("This page is for students.")
        return

    student_id = st.session_state.user["user_id"]
    st.markdown("## 👥 Join a Class")
    st.caption("Enter class code from your teacher")

    raw = st.text_input(
        label="Class Code",
        placeholder="e.g. FIN5A2024",
        key="class_code_input",
        label_visibility="collapsed"
    )

    # custom button style
    st.markdown(
        """
        <style>
        .stButton>button#join_class_btn {
            background-color: #28a745; /* Bootstrap green */
            color: white;
            border-radius: 5px;
            padding: 10px 16px;
            font-weight: 600;
        }
        .stButton>button#join_class_btn:hover {
            background-color: #218838;
            color: white;
        }
        </style>
        """,
        unsafe_allow_html=True,
    )

    if st.button("Join Class", key="join_class_btn"):
        code = (raw or "").strip().upper()
        if not code:
            st.error("Enter a class code.")
        else:
            try:
                _join_class_by_code(student_id, code)
                st.success("🎉 Joined the class!")
                st.rerun()
            except ValueError as e:
                st.error(str(e))
            except Exception as e:
                st.error(f"Could not join class: {e}")

    st.markdown("---")
    st.markdown("## Your Classes")

    classes = _list_classes_for_student(student_id)
    if not classes:
        st.info("You haven’t joined any classes yet. Ask your teacher for a class code.")
        return

    # one card per class
    for c in classes:
        class_id = c["class_id"]
        counts   = _class_content_counts(class_id)             # lessons/quizzes count
        prog     = _student_class_progress(student_id, class_id)

        st.markdown(f"### {c.get('name', 'Untitled Class')}")
        st.caption(
            f"Teacher: {c.get('teacher_name','—')} • "
            f"Code: {c.get('code','—')} • "
            f"Joined: {str(c.get('joined_at',''))[:10] if c.get('joined_at') else '—'}"
        )

        st.progress(_progress_0_1(prog.get("overall_progress", 0)))
        avg_pct = int(round(100 * _progress_0_1(prog.get("avg_score", 0))))
        st.caption(
            f"{prog.get('lessons_completed', 0)}/{prog.get('total_assigned_lessons', 0)} lessons completed • "
            f"Avg quiz: {avg_pct}%"
        )

        # top metrics
        m1, m2, m3, m4 = st.columns(4)
        m1.metric("Lessons", counts.get("lessons", 0))
        m2.metric("Quizzes", counts.get("quizzes", 0))
        m3.metric("Overall", f"{int(round(100 * _progress_0_1(prog.get('overall_progress', 0))))}%")
        m4.metric("Avg Quiz", f"{avg_pct}%")

        # Leave class
        leave_col, _ = st.columns([1, 3])
        with leave_col:
            if st.button("🚪 Leave Class", key=f"leave_{class_id}"):
                try:
                    _leave_class(student_id, class_id)
                    st.toast("Left class.", icon="👋")
                    st.rerun()
                except Exception as e:
                    st.error(f"Could not leave class: {e}")

        # Assignments for THIS class with THIS student's progress
        st.markdown("#### Teacher Lessons & Quizzes")
        rows = _student_assignments_for_class(student_id, class_id)
        if not rows:
            st.info("No assignments yet.")
        else:
            lessons_tab, quizzes_tab = st.tabs(["📘 Lessons", "🏆 Quizzes"])

            with lessons_tab:
                for r in rows:
                    if r.get("lesson_id") is None:
                        continue

                    status = r.get("status") or "not_started"
                    pos = r.get("current_pos") or 0
                    # if backend returns explicit progress % or 0..1, keep it sane:
                    pct = r.get("progress")
                    if pct is None:
                        # fallback: estimate from position
                        pct = 1.0 if status == "completed" else min(0.95, float(pos or 0) * 0.1)

                    st.subheader(r.get("title", "Untitled"))
                    due = r.get("due_at")
                    due_txt = f"Due: {str(due)[:10]}" if due else "—"
                    st.caption(f"{r.get('subject','General')} • {r.get('level','Beginner')} • {due_txt}")
                    st.progress(_progress_0_1(pct))

                    c1, c2 = st.columns(2)
                    with c1:
                        if st.button("▶️ Start Lesson", key=f"start_lesson_{r.get('assignment_id')}"):
                            lesson_id = int(r.get("lesson_id"))
                            assignment_id = int(r.get("assignment_id"))

                            try:
                                _mark_assignment_started(student_id, assignment_id)
                                _set_assignment_progress(student_id, assignment_id, current_pos=1, progress=0.05)
                            except Exception as e:
                                st.warning(f"Could not mark as started yet. Continuing anyway. {e}")

                            st.session_state.selected_lesson = lesson_id
                            st.session_state.selected_assignment = assignment_id
                            st.session_state.lesson_route = {
                                "source": "teacher",
                                "lesson_id": lesson_id,
                                "assignment_id": assignment_id,
                            }
                            st.session_state.current_page = "Lessons"
                            st.rerun()
                    with c2:
                        st.write(f"Status: **{status}**")

            with quizzes_tab:
                any_quiz = False
                for r in rows:
                    quiz_id = r.get("quiz_id")
                    if not quiz_id:
                        continue
                    any_quiz = True

                    st.subheader(r.get("title", "Untitled"))
                    score, total = r.get("score"), r.get("total")
                    if score is not None and total:
                        try:
                            pct = int(round(100 * float(score) / float(total)))
                            st.caption(f"Last score: {pct}%")
                        except Exception:
                            st.caption("Last score: —")
                    else:
                        st.caption("No submission yet")

                    # pass quiz & assignment to the Quiz page
                    if st.button("📝 Start Quiz", key=f"start_quiz_{class_id}_{quiz_id}"):
                        st.session_state.selected_quiz = quiz_id
                        st.session_state.current_assignment = r.get("assignment_id")
                        st.session_state.current_page = "Quiz"
                        st.rerun()

                if not any_quiz:
                    st.info("No quizzes yet for this class.")

        st.markdown("---")