"""Subscription billing for Nexus POS SaaS."""

from tenant_db import get_master_conn

PLANS = {
    'free':       {'name': 'Gratis',     'price_mxn': 0,    'max_products': 100,   'max_employees': 2,    'max_branches': 1},
    'basic':      {'name': 'Basico',     'price_mxn': 499,  'max_products': 5000,  'max_employees': 5,    'max_branches': 2},
    'pro':        {'name': 'Pro',        'price_mxn': 1499, 'max_products': 50000, 'max_employees': 15,   'max_branches': 5},
    'enterprise': {'name': 'Enterprise', 'price_mxn': 3999, 'max_products': None,  'max_employees': None, 'max_branches': None},
}

PLAN_ORDER = ['free', 'basic', 'pro', 'enterprise']


def get_plan(tenant_id):
    """Get current plan for a tenant."""
    conn = get_master_conn()
    cur = conn.cursor()
    cur.execute("SELECT plan FROM tenants WHERE id = %s", (tenant_id,))
    row = cur.fetchone()
    cur.close()
    conn.close()
    if not row:
        return 'free'
    plan_key = row[0] or 'free'
    if plan_key not in PLANS:
        plan_key = 'free'
    return plan_key


def get_plan_details(tenant_id):
    """Get plan key + full details for a tenant."""
    plan_key = get_plan(tenant_id)
    return {**PLANS[plan_key], 'key': plan_key}


def next_plan(current_plan):
    """Return the next upgrade plan key, or None if already enterprise."""
    idx = PLAN_ORDER.index(current_plan) if current_plan in PLAN_ORDER else 0
    if idx < len(PLAN_ORDER) - 1:
        return PLAN_ORDER[idx + 1]
    return None


def check_limit(tenant_id, resource, current_count):
    """Check if tenant is within plan limits.

    Args:
        tenant_id: Tenant ID
        resource: One of 'max_products', 'max_employees', 'max_branches'
        current_count: Current count of that resource

    Returns:
        (allowed: bool, limit: int|None, current: int)
    """
    plan_key = get_plan(tenant_id)
    plan = PLANS[plan_key]
    limit = plan.get(resource)
    if limit is None:
        return (True, None, current_count)
    return (current_count < limit, limit, current_count)


def upgrade_plan(tenant_id, new_plan):
    """Change tenant's plan."""
    if new_plan not in PLANS:
        return {'error': f'Invalid plan: {new_plan}'}
    conn = get_master_conn()
    cur = conn.cursor()
    cur.execute("UPDATE tenants SET plan = %s WHERE id = %s", (new_plan, tenant_id))
    conn.commit()
    cur.close()
    conn.close()
    return {'success': True, 'plan': new_plan, 'details': PLANS[new_plan]}