from __future__ import annotations

from decimal import Decimal

from mousehold_domain import (
    FinancialEventStatus,
    PaymentLineStatus,
    PaymentStatus,
    PlanningStatus,
    ReconciliationStatus,
    SettlementStatus,
)
from sqlalchemy import select
from sqlalchemy.orm import Session

from .. import models
from ..schemas import ProjectSummary


def _money(value: Decimal | int | str = "0.00") -> Decimal:
    return Decimal(value).quantize(Decimal("0.01"))


def calculate_project_summary(session: Session, project_id: str) -> ProjectSummary:
    project = session.get(models.Project, project_id)
    if not project:
        raise ValueError("Project not found")

    budget_lines = list(
        session.scalars(
            select(models.ProjectBudgetLine).where(
                models.ProjectBudgetLine.project_id == project_id
            )
        ).all()
    )
    planned_items = list(
        session.scalars(
            select(models.ProjectPlannedItem).where(
                models.ProjectPlannedItem.project_id == project_id
            )
        ).all()
    )
    payment_lines = list(
        session.scalars(
            select(models.PaymentLine)
            .join(
                models.ProjectPlannedItem,
                models.PaymentLine.planned_item_id == models.ProjectPlannedItem.id,
            )
            .where(models.ProjectPlannedItem.project_id == project_id)
        ).all()
    )
    linked_events = list(
        session.scalars(
            select(models.FinancialEvent).where(models.FinancialEvent.project_id == project_id)
        ).all()
    )

    budgeted_total = _money(sum((line.budgeted_amount for line in budget_lines), Decimal("0.00")))
    committed_total = _money(
        sum(
            (
                item.committed_amount
                if item.committed_amount is not None
                else item.estimated_amount
                if item.planning_status == PlanningStatus.COMMITTED
                else Decimal("0.00")
            )
            for item in planned_items
        )
    )
    paid_total = _money(
        sum(
            (
                line.amount
                for line in payment_lines
                if line.status in {PaymentLineStatus.PAID, PaymentLineStatus.RECONCILED}
            ),
            Decimal("0.00"),
        )
        + sum(
            (
                event.amount
                for event in linked_events
                if event.status
                in {
                    FinancialEventStatus.CONFIRMED,
                    FinancialEventStatus.BOOKED,
                    FinancialEventStatus.SETTLED,
                }
            ),
            Decimal("0.00"),
        )
    )
    reconciled_total = _money(
        sum(
            (line.amount for line in payment_lines if line.status == PaymentLineStatus.RECONCILED),
            Decimal("0.00"),
        )
    )
    settled_total = _money(
        sum(
            (
                item.committed_amount or item.estimated_amount
                for item in planned_items
                if item.settlement_status == SettlementStatus.SETTLED
            ),
            Decimal("0.00"),
        )
    )
    due_later_total = _money(max(Decimal("0.00"), committed_total - paid_total))
    remaining_uncommitted_budget = _money(budgeted_total - committed_total)

    open_actions: list[str] = []
    for item in planned_items:
        expected = item.committed_amount or item.estimated_amount
        if item.planning_status == PlanningStatus.COMMITTED and item.payment_status in {
            PaymentStatus.UNPAID,
            PaymentStatus.PARTIALLY_PAID,
        }:
            open_actions.append(f"{item.description} still has payment due.")
        if item.reconciliation_status == ReconciliationStatus.NO_EVIDENCE and expected > 0:
            open_actions.append(f"{item.description} needs evidence.")

    return ProjectSummary(
        project_id=project.id,
        currency=project.currency,
        budgeted_total=budgeted_total,
        committed_total=committed_total,
        paid_total=paid_total,
        reconciled_total=reconciled_total,
        settled_total=settled_total,
        due_later_total=due_later_total,
        remaining_uncommitted_budget=remaining_uncommitted_budget,
        open_actions=open_actions,
    )