"""
Medications API - medication scheduling, logging, and adherence tracking
"""

import os
import uuid
import flask
import jwt
import core.auth as auth
import core.postgres as postgres


def _get_user_uuid(token):
    try:
        payload = jwt.decode(token, os.getenv("JWT_SECRET"), algorithms=["HS256"])
        return payload.get("sub")
    except (jwt.ExpiredSignatureError, jwt.InvalidTokenError):
        return None


def _auth(request):
    """Extract and verify token. Returns user_uuid or None."""
    header = request.headers.get("Authorization", "")
    if not header.startswith("Bearer "):
        return None
    token = header[7:]
    user_uuid = _get_user_uuid(token)
    if not user_uuid or not auth.verifyLoginToken(token, userUUID=user_uuid):
        return None
    return user_uuid


def register(app):

    # ── Medications CRUD ──────────────────────────────────────────

    @app.route("/api/medications", methods=["GET"])
    def api_listMedications():
        """List all medications for the logged-in user."""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        meds = postgres.select("medications", where={"user_uuid": user_uuid}, order_by="name")
        return flask.jsonify(meds), 200

    @app.route("/api/medications", methods=["POST"])
    def api_addMedication():
        """Add a medication. Body: {name, dosage, unit, frequency, times: ["08:00","20:00"], notes?}"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        data = flask.request.get_json()
        if not data:
            return flask.jsonify({"error": "missing body"}), 400
        required = ["name", "dosage", "unit", "frequency"]
        missing = [f for f in required if not data.get(f)]
        if missing:
            return flask.jsonify({"error": f"missing required fields: {', '.join(missing)}"}), 400
        data["id"] = str(uuid.uuid4())
        data["user_uuid"] = user_uuid
        data["times"] = data.get("times", [])
        data["active"] = True
        med = postgres.insert("medications", data)
        return flask.jsonify(med), 201

    @app.route("/api/medications/<med_id>", methods=["GET"])
    def api_getMedication(med_id):
        """Get a single medication with its schedule."""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        return flask.jsonify(med), 200

    @app.route("/api/medications/<med_id>", methods=["PUT"])
    def api_updateMedication(med_id):
        """Update medication details. Body: {name?, dosage?, unit?, frequency?, times?, notes?, active?}"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        data = flask.request.get_json()
        if not data:
            return flask.jsonify({"error": "missing body"}), 400
        existing = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not existing:
            return flask.jsonify({"error": "not found"}), 404
        allowed = ["name", "dosage", "unit", "frequency", "times", "notes", "active"]
        updates = {k: v for k, v in data.items() if k in allowed}
        if not updates:
            return flask.jsonify({"error": "no valid fields to update"}), 400
        result = postgres.update("medications", updates, {"id": med_id, "user_uuid": user_uuid})
        return flask.jsonify(result[0] if result else {}), 200

    @app.route("/api/medications/<med_id>", methods=["DELETE"])
    def api_deleteMedication(med_id):
        """Delete a medication and its logs."""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        existing = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not existing:
            return flask.jsonify({"error": "not found"}), 404
        postgres.delete("med_logs", {"medication_id": med_id})
        postgres.delete("medications", {"id": med_id, "user_uuid": user_uuid})
        return flask.jsonify({"deleted": True}), 200

    # ── Medication Logging (take / skip / snooze) ─────────────────

    @app.route("/api/medications/<med_id>/take", methods=["POST"])
    def api_takeMedication(med_id):
        """Log that a dose was taken. Body: {scheduled_time?, notes?}"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        data = flask.request.get_json() or {}
        log_entry = {
            "id": str(uuid.uuid4()),
            "medication_id": med_id,
            "user_uuid": user_uuid,
            "action": "taken",
            "scheduled_time": data.get("scheduled_time"),
            "notes": data.get("notes"),
        }
        log = postgres.insert("med_logs", log_entry)
        return flask.jsonify(log), 201

    @app.route("/api/medications/<med_id>/skip", methods=["POST"])
    def api_skipMedication(med_id):
        """Log a skipped dose. Body: {scheduled_time?, reason?}"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        data = flask.request.get_json() or {}
        log_entry = {
            "id": str(uuid.uuid4()),
            "medication_id": med_id,
            "user_uuid": user_uuid,
            "action": "skipped",
            "scheduled_time": data.get("scheduled_time"),
            "notes": data.get("reason"),
        }
        log = postgres.insert("med_logs", log_entry)
        return flask.jsonify(log), 201

    @app.route("/api/medications/<med_id>/snooze", methods=["POST"])
    def api_snoozeMedication(med_id):
        """Snooze a reminder. Body: {minutes: 15}"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        data = flask.request.get_json() or {}
        minutes = data.get("minutes", 15)
        return flask.jsonify({"snoozed_until_minutes": minutes}), 200

    # ── Medication Log / History ──────────────────────────────────

    @app.route("/api/medications/<med_id>/log", methods=["GET"])
    def api_getMedLog(med_id):
        """Get dose log for a medication. Query: ?days=30"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        days = flask.request.args.get("days", 30, type=int)
        logs = postgres.select(
            "med_logs",
            where={"medication_id": med_id},
            order_by="created_at DESC",
            limit=days * 10,
        )
        return flask.jsonify(logs), 200

    @app.route("/api/medications/today", methods=["GET"])
    def api_todaysMeds():
        """Get today's medication schedule with taken/pending status."""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        meds = postgres.select("medications", where={"user_uuid": user_uuid, "active": True})
        from datetime import datetime
        today = datetime.now().strftime("%Y-%m-%d")
        result = []
        for med in meds:
            times = med.get("times", [])
            taken_times = [
                log["scheduled_time"]
                for log in postgres.select(
                    "med_logs",
                    where={"medication_id": med["id"], "action": "taken"},
                )
                if log.get("scheduled_time", "").startswith(today)
            ]
            result.append({
                "medication": med,
                "scheduled_times": times,
                "taken_times": taken_times,
            })
        return flask.jsonify(result), 200

    # ── Adherence Stats ───────────────────────────────────────────

    @app.route("/api/medications/adherence", methods=["GET"])
    def api_adherenceStats():
        """Get adherence stats across all meds. Query: ?days=30"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        days = flask.request.args.get("days", 30, type=int)
        meds = postgres.select("medications", where={"user_uuid": user_uuid, "active": True})
        result = []
        for med in meds:
            logs = postgres.select(
                "med_logs",
                where={"medication_id": med["id"]},
                limit=days * 10,
            )
            taken = sum(1 for log in logs if log.get("action") == "taken")
            skipped = sum(1 for log in logs if log.get("action") == "skipped")
            total = taken + skipped
            adherence = (taken / total * 100) if total > 0 else 0
            result.append({
                "medication_id": med["id"],
                "name": med["name"],
                "taken": taken,
                "skipped": skipped,
                "adherence_percent": round(adherence, 1),
            })
        return flask.jsonify(result), 200

    @app.route("/api/medications/<med_id>/adherence", methods=["GET"])
    def api_medAdherence(med_id):
        """Get adherence stats for a single medication. Query: ?days=30"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        days = flask.request.args.get("days", 30, type=int)
        logs = postgres.select(
            "med_logs",
            where={"medication_id": med_id},
            limit=days * 10,
        )
        taken = sum(1 for log in logs if log.get("action") == "taken")
        skipped = sum(1 for log in logs if log.get("action") == "skipped")
        total = taken + skipped
        adherence = (taken / total * 100) if total > 0 else 0
        return flask.jsonify({
            "medication_id": med_id,
            "name": med["name"],
            "taken": taken,
            "skipped": skipped,
            "adherence_percent": round(adherence, 1),
        }), 200

    # ── Refills ───────────────────────────────────────────────────

    @app.route("/api/medications/<med_id>/refill", methods=["PUT"])
    def api_setRefill(med_id):
        """Set refill info. Body: {quantity_remaining, refill_date?, pharmacy_notes?}"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        med = postgres.select_one("medications", {"id": med_id, "user_uuid": user_uuid})
        if not med:
            return flask.jsonify({"error": "not found"}), 404
        data = flask.request.get_json()
        if not data:
            return flask.jsonify({"error": "missing body"}), 400
        allowed = ["quantity_remaining", "refill_date", "pharmacy_notes"]
        updates = {k: v for k, v in data.items() if k in allowed}
        if not updates:
            return flask.jsonify({"error": "no valid fields to update"}), 400
        result = postgres.update("medications", updates, {"id": med_id, "user_uuid": user_uuid})
        return flask.jsonify(result[0] if result else {}), 200

    @app.route("/api/medications/refills-due", methods=["GET"])
    def api_refillsDue():
        """Get medications that need refills soon. Query: ?days_ahead=7"""
        user_uuid = _auth(flask.request)
        if not user_uuid:
            return flask.jsonify({"error": "unauthorized"}), 401
        days_ahead = flask.request.args.get("days_ahead", 7, type=int)
        from datetime import datetime, timedelta
        cutoff = (datetime.now() + timedelta(days=days_ahead)).strftime("%Y-%m-%d")
        meds = postgres.select(
            "medications",
            where={"user_uuid": user_uuid},
        )
        due = []
        for med in meds:
            qty = med.get("quantity_remaining")
            refill_date = med.get("refill_date")
            if qty is not None and qty <= 7:
                due.append(med)
            elif refill_date and refill_date <= cutoff:
                due.append(med)
        return flask.jsonify(due), 200