import os
import sqlite3
import pathlib
from functools import wraps
from flask import Flask, render_template, request, jsonify, redirect, url_for, session

APP = Flask(__name__)
# Use environment variable for secret key (required for Spaces)
APP.secret_key = os.environ.get("SECRET_KEY", "dev-minerva-lite")
ROOT = pathlib.Path(__file__).parent
# Use /tmp for DB on Hugging Face Spaces
if "SPACE_ID" in os.environ:
    DB_PATH = pathlib.Path("/tmp/minerva.sqlite3")
    APP.config["SESSION_COOKIE_SAMESITE"] = "None"
    APP.config["SESSION_COOKIE_SECURE"] = True
else:
    DB_PATH = ROOT / "db" / "minerva.sqlite3"

STEP_DESTINATIONS = {
    "home": {"endpoint": "registration_menu", "label": "Registration Menu"},
    "search": {"endpoint": "search", "label": "Search Class Schedule"},
    "add_drop": {"endpoint": "add_drop", "label": "Add or Drop Course Sections"},
    "schedule": {"endpoint": "schedule", "label": "Student Schedule"},
    "schedule_week": {"endpoint": "schedule_week", "label": "Weekly Schedule View"},
    "accounts": {"endpoint": "accounts", "label": "Tuition Fee and Legal Status"},
}

STEP_KEYS_BY_ENDPOINT = {
    "registration_menu": "home",
    "search": "search",
    "add_drop": "add_drop",
    "schedule": "schedule",
    "schedule_week": "schedule_week",
    "accounts": "accounts",
}


def require_term(step_key):
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            if not session.get("term_confirmed"):
                return redirect(url_for("select_term", next=step_key))
            return func(*args, **kwargs)
        return wrapper
    return decorator


# Always ensure DB is seeded: if DB file is missing or 'courses' table is missing, run seed
def ensure_db_seeded():
    need_seed = False
    if not DB_PATH.exists():
        need_seed = True
    else:
        try:
            con = sqlite3.connect(DB_PATH)
            cur = con.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='courses'")
            if not cur.fetchone():
                need_seed = True
            con.close()
        except Exception:
            need_seed = True
    if need_seed:
        import seed  # side effect: creates DB

ensure_db_seeded()

def q(sql, *params):
    con = sqlite3.connect(DB_PATH)
    con.row_factory = sqlite3.Row
    cur = con.execute(sql, params)
    rows = [dict(r) for r in cur.fetchall()]
    con.close()
    return rows


def execute(sql, *params):
    with sqlite3.connect(DB_PATH) as con:
        con.execute(sql, params)
        con.commit()


@APP.get("/status")
def status():
    return jsonify({"service": "minerva-lite", "ok": True})


@APP.get("/")
def registration_menu():
    msg = request.args.get("msg", "")
    return render_template("registration_menu.html", msg=msg)


@APP.get("/search")
@require_term("search")
def search():
    subject = request.args.get("subject", "").strip().upper()
    number = request.args.get("number", "").strip()
    title = request.args.get("title", "").strip()
    campus = request.args.get("campus", "").strip()
    term = session.get("term", "Fall 2025")

    sql = "SELECT * FROM courses WHERE 1=1"
    args = []
    if term:
        sql += " AND term = ?"
        args.append(term)
    if subject:
        sql += " AND subject = ?"
        args.append(subject)
    if number:
        sql += " AND number LIKE ?"
        args.append(f"%{number}%")
    if title:
        sql += " AND lower(title) LIKE ?"
        args.append(f"%{title.lower()}%")
    if campus:
        sql += " AND campus = ?"
        args.append(campus)
    sql += " ORDER BY subject, number"
    results = q(sql, *args)
    return render_template("search.html", results=results)


@APP.post("/add")
def add_course():
    crn = request.form.get("crn", "").strip()
    if not crn:
        return redirect(url_for("add_drop", msg="Enter a CRN."))
    # Check if exists and open
    rows = q("SELECT * FROM courses WHERE crn=?", crn)
    if not rows:
        return redirect(url_for("add_drop", msg="Invalid CRN."))
    course = rows[0]
    # Ensure CRN belongs to the currently selected term
    current_term = session.get("term", "Fall 2025")
    if course.get("term") != current_term:
        return redirect(url_for("add_drop", msg=f"CRN not in {current_term} term."))
    reg = q("SELECT * FROM registrations WHERE student_id=1 AND crn=?", crn)
    if reg:
        return redirect(url_for("add_drop", msg="Already registered."))
    if course["seats_taken"] >= course["seats_total"]:
        return redirect(url_for("add_drop", msg="Section full."))
    execute("INSERT INTO registrations(student_id,crn) VALUES(1,?)", crn)
    execute(
        "UPDATE courses SET seats_taken = seats_taken + 1 WHERE crn=?",
        crn,
    )
    return redirect(url_for("schedule", msg="Added CRN %s" % crn))


@APP.post("/drop")
def drop_course():
    crn = request.form.get("crn", "").strip()
    reg = q("SELECT * FROM registrations WHERE student_id=1 AND crn=?", crn)
    if not reg:
        return redirect(url_for("schedule", msg="Not registered."))
    execute("DELETE FROM registrations WHERE student_id=1 AND crn=?", crn)
    execute(
        "UPDATE courses SET seats_taken = CASE WHEN seats_taken>0 THEN seats_taken-1 ELSE 0 END WHERE crn=?",
        crn,
    )
    return redirect(url_for("schedule", msg="Dropped CRN %s" % crn))


@APP.get("/add-drop")
@require_term("add_drop")
def add_drop():
    msg = request.args.get("msg", "")
    current_term = session.get("term", "Fall 2025")
    regs = q(
        "SELECT c.* FROM registrations r JOIN courses c ON r.crn=c.crn WHERE r.student_id=1 AND c.term=? ORDER BY c.subject, c.number",
        current_term,
    )
    return render_template("add_drop.html", regs=regs, msg=msg)


@APP.get("/schedule")
@require_term("schedule")
def schedule():
    msg = request.args.get("msg", "")
    current_term = session.get("term", "Fall 2025")
    regs = q(
        "SELECT c.* FROM registrations r JOIN courses c ON r.crn=c.crn WHERE r.student_id=1 AND c.term=? ORDER BY c.subject, c.number",
        current_term,
    )
    return render_template("schedule.html", regs=regs, msg=msg)


def _parse_time_range(range_str):
    try:
        s, e = [t.strip() for t in range_str.split("-")]
        sh, sm = [int(x) for x in s.split(":")]
        eh, em = [int(x) for x in e.split(":")]
        return sh * 60 + sm, eh * 60 + em
    except Exception:
        return None, None


@APP.get("/schedule-week")
@require_term("schedule_week")
def schedule_week():
    # Build weekly event blocks for registered sections
    current_term = session.get("term", "Fall")
    regs = q(
        "SELECT c.* FROM registrations r JOIN courses c ON r.crn=c.crn WHERE r.student_id=1 AND c.term=?",
        current_term,
    )
    start_day_min = 8 * 60  # 08:00 grid start
    end_day_min = 18 * 60   # 18:00 grid end
    span = end_day_min - start_day_min
    grid_px = 800  # matches CSS .grid-body height
    day_map = {"M": 1, "T": 2, "W": 3, "R": 4, "F": 5}

    events = []
    for c in regs:
        smin, emin = _parse_time_range(c.get("time") or "")
        if smin is None:
            continue
        duration = max(emin - smin, 30)
        # pixel-perfect placement using the same 800px grid height
        top_px = max(int(round((smin - start_day_min) / span * grid_px)), 0)
        height_px = max(int(round(duration / span * grid_px)), 2)
        for ch in (c.get("days") or ""):  # e.g., "MWF" or "TR"
            if ch in day_map:
                events.append({
                    "day_col": day_map[ch],
                    "title": f"{c['subject']} {c['number']}",
                    "subtitle": c["title"],
                    "time": c["time"],
                    "top_px": top_px,
                    "height_px": height_px,
                    "crn": c["crn"],
                })

    # Time labels every hour for the left rail
    time_labels = []
    for h in range(8, 18):
        time_labels.append(f"{h:02d}:00")

    return render_template(
        "schedule_week.html",
        events=events,
        time_labels=time_labels,
    )


@APP.get("/accounts")
@require_term("accounts")
def accounts():
    return render_template("accounts.html")


@APP.post("/set-term")
def set_term():
    term = request.form.get("term", "").strip().title()
    if term not in ("Fall 2025", "Winter 2026", "Summer 2026"):
        return redirect(url_for("registration_menu", msg="Invalid term."))
    session["term"] = term
    session["term_confirmed"] = True
    next_key = request.form.get("next", "").strip()
    if next_key in STEP_DESTINATIONS:
        endpoint = STEP_DESTINATIONS[next_key]["endpoint"]
        return redirect(url_for(endpoint))
    # Redirect back to the referrer if possible
    ref = request.headers.get("Referer")
    return redirect(ref or url_for("registration_menu", msg=f"Term set to {term}"))


@APP.get("/select-term")
def select_term():
    next_key = request.args.get("next", "search").strip()
    destination = STEP_DESTINATIONS.get(next_key, STEP_DESTINATIONS["search"])
    if request.args.get("reset"):
        session["term_confirmed"] = False
    return render_template(
        "select_term.html",
        next_key=next_key,
        destination_label=destination["label"],
    )


@APP.context_processor
def inject_term():
    current_step_key = STEP_KEYS_BY_ENDPOINT.get(request.endpoint, "")
    if request.endpoint == "select_term":
        current_step_key = request.args.get("next", current_step_key or "search")
    return {
        "current_term": session.get("term", "Fall 2025"),
        "terms": ["Fall 2025", "Winter 2026", "Summer 2026"],
        "term_confirmed": session.get("term_confirmed", False),
        "current_step_key": current_step_key,
    }


@APP.get("/reset")
def reset():
    if DB_PATH.exists():
        DB_PATH.unlink()
    import seed  # re-seed
    return jsonify({"reset": True})


import os
if __name__ == "__main__":
    port = int(os.environ.get("PORT", 8000))
    APP.run(host="0.0.0.0", port=port)