from __future__ import annotations

import logging
import time
from typing import List, Tuple

from models import AnomalyFlag, NormalisedInvoice, DeliveryCountMap, AgentTraceEntry
from tracer import make_trace_entry

logger = logging.getLogger(__name__)

AGENT_NAME = "Reconciliation_Agent"
AGENT_VERSION = "1.0.0"


class ReconciliationAgent:
    def run(
        self,
        invoice: NormalisedInvoice,
        delivery_count_map: DeliveryCountMap,
        audit_run_id: str,
    ) -> Tuple[List[AnomalyFlag], List[str], AgentTraceEntry]:
        t_start = time.monotonic()
        flags: List[AnomalyFlag] = []
        invoiced_product_ids: set[str] = set()

        for item in invoice.items:
            if item.product_id is None:
                continue

            invoiced_product_ids.add(item.product_id)
            delivered = delivery_count_map.get(item.product_id, 0)

            if item.quantity > delivered:
                shortage = item.quantity - delivered
                flags.append(AnomalyFlag(
                    flag_type="delivery_shortage",
                    product_id=item.product_id,
                    product_name=item.product_normalized or item.product_raw,
                    amount_inr=shortage * item.unit_price,
                    description=(
                        f"{item.product_normalized or item.product_raw}: "
                        f"invoiced {item.quantity}, delivered {delivered}, short {shortage}"
                    ),
                    action_item=(
                        f"Request delivery of {shortage:.0f} missing "
                        f"{item.product_normalized or item.product_raw} "
                        f"or credit note for ₹{shortage * item.unit_price:.2f}"
                    ),
                    metadata={
                        "invoice_quantity": item.quantity,
                        "delivered_quantity": delivered,
                        "shortage_quantity": shortage,
                        "unit_price": item.unit_price,
                    },
                ))

        # Products in delivery photos but NOT on invoice
        unexpected = [
            pid for pid in delivery_count_map
            if pid not in invoiced_product_ids
        ]

        t_end = time.monotonic()
        n_flags = len(flags)
        n_unexpected = len(unexpected)

        trace = make_trace_entry(
            agent_name=AGENT_NAME,
            agent_version=AGENT_VERSION,
            audit_run_id=audit_run_id,
            t_start=t_start,
            t_end=t_end,
            input_summary=(
                f"{len(invoice.items)} invoice items; "
                f"{len(delivery_count_map)} delivery entries"
            ),
            output_summary=f"{n_flags} shortage flags; {n_unexpected} unexpected deliveries",
        )
        return flags, unexpected, trace