"""Customer account statements.

Generates printable, one-customer-per-page account statements for customers with
overdue invoices, formatted for a standard double-window envelope. Statement
generation also books a late-payment fee to the ledger (see the late-fee helpers
added alongside the generator).
"""

import frappe
from frappe import _
from frappe.utils import getdate, nowdate

# Roles allowed to run collections/statement actions.
ALLOWED_ROLES = [
    "System Manager",
    "Sales User",
    "Sales Manager",
    "Accounts User",
    "Accounts Manager",
]


@frappe.whitelist()
def get_customers_with_overdue_invoices():
    """Return one row per customer that has at least one overdue Sales Invoice.

    A Sales Invoice is overdue when it is submitted, still has an outstanding
    balance, and its due date is in the past.
    """
    frappe.only_for(ALLOWED_ROLES)

    today = nowdate()
    rows = frappe.get_all(
        "Sales Invoice",
        filters={
            "docstatus": 1,
            "outstanding_amount": [">", 0],
            "due_date": ["<", today],
        },
        fields=[
            "customer",
            "customer_name",
            "count(name) as overdue_count",
            "sum(outstanding_amount) as total_outstanding",
            "min(due_date) as oldest_due_date",
        ],
        group_by="customer, customer_name",
        order_by="total_outstanding desc",
    )

    for row in rows:
        row["max_days_overdue"] = (
            (getdate(today) - getdate(row.oldest_due_date)).days
            if row.oldest_due_date
            else 0
        )

    return rows


def _aging_bucket(days_overdue):
    """Map days-overdue to a standard aging bucket label."""
    if days_overdue <= 0:
        return "Current"
    if days_overdue <= 30:
        return "1-30"
    if days_overdue <= 60:
        return "31-60"
    if days_overdue <= 90:
        return "61-90"
    return "90+"


def _get_outstanding_invoices(customer):
    """Return all open (submitted, unpaid) Sales Invoices for a customer.

    The statement lists the full open balance, so this includes not-yet-due
    invoices; each row is annotated with days overdue, an overdue flag, and its
    aging bucket.
    """
    today = getdate(nowdate())
    invoices = frappe.get_all(
        "Sales Invoice",
        filters={
            "customer": customer,
            "docstatus": 1,
            "outstanding_amount": [">", 0],
        },
        fields=[
            "name",
            "posting_date",
            "due_date",
            "outstanding_amount",
            "grand_total",
            "company",
        ],
        order_by="due_date asc",
    )

    for inv in invoices:
        due = getdate(inv.due_date) if inv.due_date else None
        days = (today - due).days if due else 0
        inv["days_overdue"] = days if days > 0 else 0
        inv["is_overdue"] = days > 0
        inv["aging_bucket"] = _aging_bucket(inv["days_overdue"])

    return invoices