import math
from flask import Blueprint, render_template, request, redirect, url_for, flash
from app.auth import login_required, get_current_user
from app.db import query, query_one, execute, execute_returning

bp = Blueprint("checkin", __name__)


def calculate_bmi(weight_kg, height_cm):
    """Calculate BMI from weight (kg) and height (cm)."""
    if not weight_kg or not height_cm or float(height_cm) == 0:
        return None
    h_m = float(height_cm) / 100.0
    return round(float(weight_kg) / (h_m * h_m), 1)


def check_milestones(user_id, user):
    """Check and award any new milestones after a check-in."""
    checkins = query(
        "SELECT weight_kg, checked_in_at FROM checkins WHERE user_id = %s ORDER BY checked_in_at ASC",
        (user_id,),
    )
    if not checkins:
        return

    starting = float(user.get("starting_weight_kg") or checkins[0]["weight_kg"])
    current = float(checkins[-1]["weight_kg"])
    total_lost = starting - current
    count = len(checkins)

    milestone_checks = [
        ("first_checkin", count >= 1),
        ("5_checkins", count >= 5),
        ("10_checkins", count >= 10),
        ("25_checkins", count >= 25),
        ("lost_1kg", total_lost >= 1),
        ("lost_2kg", total_lost >= 2),
        ("lost_5kg", total_lost >= 5),
        ("lost_10kg", total_lost >= 10),
        ("lost_15kg", total_lost >= 15),
        ("lost_20kg", total_lost >= 20),
    ]

    for key, achieved in milestone_checks:
        if achieved:
            try:
                execute(
                    "INSERT INTO milestones (user_id, milestone_key) VALUES (%s, %s) ON CONFLICT DO NOTHING",
                    (user_id, key),
                )
            except Exception:
                pass


@bp.route("/checkin", methods=["GET"])
@login_required
def index():
    user = get_current_user()
    checkins = query(
        "SELECT * FROM checkins WHERE user_id = %s ORDER BY checked_in_at DESC",
        (user["id"],),
    )
    return render_template("checkin.html", user=user, checkins=checkins)


@bp.route("/checkin", methods=["POST"])
@login_required
def create():
    user = get_current_user()
    weight_kg = request.form.get("weight_kg")
    notes = request.form.get("notes", "").strip()

    if not weight_kg:
        flash("Weight is required.", "error")
        return redirect(url_for("checkin.index"))

    try:
        weight_kg = float(weight_kg)
    except ValueError:
        flash("Invalid weight value.", "error")
        return redirect(url_for("checkin.index"))

    bmi = calculate_bmi(weight_kg, user.get("height_cm"))

    checkin = execute_returning(
        """INSERT INTO checkins (user_id, weight_kg, bmi, notes)
           VALUES (%s, %s, %s, %s) RETURNING *""",
        (user["id"], weight_kg, bmi, notes or None),
    )

    # Check milestones
    check_milestones(user["id"], user)

    # If HTMX request, return just the new row
    if request.headers.get("HX-Request"):
        return render_template("partials/checkin_row.html", c=checkin, user=user)

    flash("Check-in recorded!", "success")
    return redirect(url_for("checkin.index"))


@bp.route("/checkin/<int:checkin_id>", methods=["DELETE"])
@login_required
def delete(checkin_id):
    user = get_current_user()
    execute(
        "DELETE FROM checkins WHERE id = %s AND user_id = %s",
        (checkin_id, user["id"]),
    )

    if request.headers.get("HX-Request"):
        return ""

    flash("Check-in deleted.", "info")
    return redirect(url_for("checkin.index"))