"""Groups a year's lines by category with computed figures; shared by the API and every report."""
from dataclasses import dataclass, field

from sqlalchemy import select
from sqlalchemy.orm import Session, selectinload

from .calc import LineFigures, Totals, line_figures
from .models import BudgetYear, Category, CostLine


@dataclass
class LineView:
    line: CostLine
    figures: LineFigures


@dataclass
class CategoryView:
    category: Category
    lines: list[LineView] = field(default_factory=list)
    totals: Totals = field(default_factory=Totals)

    def name(self, lang: str) -> str:
        return (self.category.name_pt if lang == "pt" else "") or self.category.name_en


@dataclass
class YearView:
    year: BudgetYear
    categories: list[CategoryView]
    revenue: Totals
    costs: Totals

    def with_lines(self, section: str | None = None) -> list[CategoryView]:
        return [c for c in self.categories if c.lines and (section is None or c.category.section == section)]


def build_year_view(db: Session, year: BudgetYear, site_id: int | None = None) -> YearView:
    categories = db.scalars(select(Category).where(Category.department_id == year.department_id)
                            .order_by(Category.sort_order, Category.id)).all()
    lines = db.scalars(
        select(CostLine)
        .where(CostLine.year_id == year.id)
        .options(selectinload(CostLine.site), selectinload(CostLine.category))
        .order_by(CostLine.sort_order, CostLine.id)
    ).all()
    views = {c.id: CategoryView(c) for c in categories}
    for line in lines:
        if site_id is not None and line.site_id != site_id:
            continue
        lv = LineView(line, line_figures(line, year.default_rate))
        cv = views.get(line.category_id)
        if cv is None:  # a line whose category was moved to another department
            cv = views[line.category_id] = CategoryView(line.category)
        cv.lines.append(lv)
        cv.totals.add(lv.figures)
    revenue, costs = Totals(), Totals()
    shown = []
    for cv in views.values():
        if not cv.lines and not (cv.category.active and cv.category.show_when_empty):
            continue
        shown.append(cv)
        target = revenue if cv.category.section == "revenue" else costs
        for lv in cv.lines:
            target.add(lv.figures)
    return YearView(year, shown, revenue, costs)