from collections import defaultdict
from django.utils import timezone

from commerce.models import ExternalProject, ProjectPayment
from finance.analytics.models import ReportingEntry
from finance.analytics.sales import ZERO, bounds, bucket, finish, months


def payment_queryset(start, end, currency, source=None, project=None):
    lower, upper = bounds(start, end)
    qs = ProjectPayment.objects.filter(
        currency=currency,
        occurred_at__gte=lower,
        occurred_at__lt=upper,
        applicable=True,
        missing_from_source=False,
    ).select_related("project", "source")
    if source:
        qs = qs.filter(source=source)
    if project is not None:
        qs = qs.filter(project_id=None if project == "unassigned" else project.pk)
    return qs


def journal_queryset(start, end, currency, source, project):
    entries = ReportingEntry.objects.filter(
        date__range=(start, end),
        currency=currency,
        voided_at__isnull=True,
        kind__in=["cash_out", "overhead", "purchase"],
    ).select_related("project")
    if source:
        entries = entries.filter(project__source=source)
    if project is not None:
        entries = entries.filter(
            project_id=None if project == "unassigned" else project.pk
        )
    return entries


def projects_report(start, end, currency, sales, source=None, project=None):
    rows = {}

    def row_for(key, name):
        if key not in rows:
            rows[key] = {
                **finish(bucket()),
                "id": key,
                "name": name,
                "paid": ZERO,
                "payment_count": 0,
                "manual_paid": ZERO,
                "overhead": ZERO,
                "purchases": ZERO,
                "archived": False,
            }
        return rows[key]

    catalog = ExternalProject.objects.all()
    if source:
        catalog = catalog.filter(source=source)
    if project is not None:
        catalog = (
            catalog.none() if project == "unassigned" else catalog.filter(pk=project.pk)
        )
    for p in catalog:
        row_for(f"project:{p.pk}", p.name)["archived"] = p.archived
    for sale_row in sales["projects"]:
        row_for(sale_row["id"], sale_row["name"]).update(sale_row)
    monthly = {
        m: {"id": m, "name": m, "paid": ZERO, "manual_paid": ZERO}
        for m in months(start, end)
    }
    categories = defaultdict(lambda: {"paid": ZERO, "payment_count": 0})
    for p in payment_queryset(start, end, currency, source, project).iterator(
        chunk_size=500
    ):
        row = row_for(
            f"project:{p.project_id}" if p.project_id else "unassigned",
            p.project.name if p.project else "Без проекта",
        )
        row["paid"] += p.amount
        row["payment_count"] += 1
        monthly[timezone.localtime(p.occurred_at).strftime("%Y-%m")]["paid"] += p.amount
        category = categories[p.expense_category or "Статья не указана"]
        category["paid"] += p.amount
        category["payment_count"] += 1
    for entry in journal_queryset(start, end, currency, source, project):
        row = row_for(
            f"project:{entry.project_id}" if entry.project_id else "unassigned",
            entry.project.name if entry.project else "Без проекта",
        )
        field = {
            "cash_out": "manual_paid",
            "overhead": "overhead",
            "purchase": "purchases",
        }[entry.kind]
        row[field] += entry.amount
        if entry.kind == "cash_out":
            monthly[entry.date.strftime("%Y-%m")]["manual_paid"] += entry.amount
    summary = {
        field: sum((r[field] for r in rows.values()), ZERO)
        for field in ["paid", "manual_paid", "overhead", "purchases", "payment_count"]
    }
    summary["unassigned_paid"] = rows.get("unassigned", {}).get("paid", ZERO)
    summary["project_count"] = catalog.count()
    return {
        "summary": summary,
        "rows": sorted(rows.values(), key=lambda r: (-r["paid"], r["name"])),
        "monthly": list(monthly.values()),
        "categories": [
            {"id": k, "name": k, **v} for k, v in sorted(categories.items())
        ],
    }