"""Долги: кто и сколько должен за взятые булки."""

from __future__ import annotations

from decimal import Decimal

from PySide6.QtCore import Qt
from PySide6.QtGui import QColor
from PySide6.QtWidgets import (
    QDialog,
    QFormLayout,
    QHeaderView,
    QLineEdit,
    QMessageBox,
    QTreeWidget,
    QTreeWidgetItem,
    QVBoxLayout,
    QWidget,
)

from .. import journal
from .. import money as m
from ..models import SALE_KIND_LABELS
from . import theme
from . import widgets as w

ROLE_SALE_ID = Qt.UserRole + 2


class PaymentDialog(QDialog):
    def __init__(self, suggested: Decimal, currency: str, parent=None):
        super().__init__(parent)
        self.setWindowTitle("Принять оплату")
        self.setMinimumWidth(340)

        layout = QVBoxLayout(self)
        layout.setContentsMargins(20, 16, 20, 16)
        layout.setSpacing(10)

        form = QFormLayout()
        form.setSpacing(8)

        self.date = w.DateInput()
        form.addRow("Дата", self.date)

        self.amount = w.MoneySpin(currency)
        self.amount.set_decimal(suggested)
        self.amount.selectAll()
        form.addRow("Сумма", self.amount)

        self.note = QLineEdit()
        form.addRow("Заметка", self.note)
        layout.addLayout(form)

        layout.addWidget(w.label(f"Долг по этой продаже: {m.fmt_money(suggested, currency)}", "dim"))
        layout.addWidget(
            w.row(None, w.button("Отмена", on_click=self.reject), w.button("Принять", "primary", self.accept))
        )
        self.amount.setFocus()


def ask_payment(parent, suggested: Decimal, currency: str) -> Decimal | None:
    """Спросить сумму оплаты. Возвращает None, если отменили."""
    dialog = PaymentDialog(suggested, currency, parent)
    if dialog.exec() != QDialog.Accepted:
        return None
    return dialog.amount.value_decimal()


class DebtsPage(QWidget):
    """Дерево: человек → его неоплаченные продажи."""

    def __init__(self, ctx, parent=None):
        super().__init__(parent)
        self.ctx = ctx

        layout = QVBoxLayout(self)
        layout.setContentsMargins(20, 18, 20, 18)
        layout.setSpacing(12)

        layout.addWidget(w.heading("Долги"))
        self.total_label = w.label("", "h2")
        layout.addWidget(
            w.row(
                w.button("Принять оплату", "primary", self.take_payment),
                w.button("Погасить целиком", on_click=self.settle_full),
                None,
                self.total_label,
            )
        )

        self.tree = QTreeWidget()
        self.tree.setHeaderLabels(["Кто / что", "Дата", "Сумма", "Оплачено", "Долг"])
        self.tree.setAlternatingRowColors(True)
        self.tree.setRootIsDecorated(True)
        self.tree.header().setStretchLastSection(False)
        self.tree.header().setSectionResizeMode(0, QHeaderView.Stretch)
        self.tree.itemDoubleClicked.connect(self.take_payment)
        layout.addWidget(self.tree, 1)

        self.empty = w.label("Никто ничего не должен.", "dim")
        layout.addWidget(self.empty)

    # --- отрисовка ---

    def refresh(self) -> None:
        doc = self.ctx.vault.doc
        currency = self.ctx.currency
        debtors = self.ctx.report.debtors

        self.tree.clear()
        for debtor in debtors:
            parent = QTreeWidgetItem(
                [debtor.name, "", "", "", m.fmt_money(debtor.debt, currency)]
            )
            font = parent.font(0)
            font.setBold(True)
            parent.setFont(0, font)
            parent.setFont(4, font)
            parent.setForeground(4, QColor(theme.WARN))
            parent.setTextAlignment(4, Qt.AlignRight | Qt.AlignVCenter)

            for sale in sorted(debtor.sales, key=lambda s: s.date):
                what = ", ".join(
                    f"{doc.product_name(line.product_id)} × {m.fmt_qty(line.qty)}"
                    for line in sale.lines
                )
                child = QTreeWidgetItem(
                    [
                        f"{SALE_KIND_LABELS.get(sale.kind, sale.kind)}: {what}",
                        sale.date.strftime("%d.%m.%Y"),
                        m.fmt_money(sale.total, currency),
                        m.fmt_money(sale.paid, currency),
                        m.fmt_money(sale.debt, currency),
                    ]
                )
                child.setData(0, ROLE_SALE_ID, sale.id)
                for column in (2, 3, 4):
                    child.setTextAlignment(column, Qt.AlignRight | Qt.AlignVCenter)
                parent.addChild(child)

            self.tree.addTopLevelItem(parent)
            parent.setExpanded(True)

        for column in range(1, 5):
            self.tree.resizeColumnToContents(column)

        total = self.ctx.report.summary.receivable
        self.total_label.setText(f"Мне должны: {m.fmt_money(total, currency)}")
        self.empty.setVisible(not debtors)
        self.tree.setVisible(bool(debtors))

    # --- действия ---

    def _selected_sale(self):
        item = self.tree.currentItem()
        if item is None:
            QMessageBox.information(self, "Не выбрано", "Выбери конкретную продажу.")
            return None

        sale_id = item.data(0, ROLE_SALE_ID)
        if sale_id is None:
            QMessageBox.information(
                self, "Выбери продажу", "Раскрой человека и выбери, за что он платит."
            )
            return None
        return self.ctx.vault.doc.sale(sale_id)

    def take_payment(self) -> None:
        sale = self._selected_sale()
        if sale is None:
            return

        amount = ask_payment(self, sale.debt, self.ctx.currency)
        if amount is None:
            return
        try:
            journal.add_sale_payment(self.ctx.vault, sale.id, amount)
        except journal.ValidationError as exc:
            QMessageBox.warning(self, "Не получилось", str(exc))
            return
        self.ctx.changed()

    def settle_full(self) -> None:
        sale = self._selected_sale()
        if sale is None:
            return
        if sale.debt <= 0:
            return
        journal.add_sale_payment(self.ctx.vault, sale.id, sale.debt)
        self.ctx.changed()