from fastapi import APIRouter, Depends

from app.core.config import settings
from app.repositories.pricing import find_effective_price_rule
from app.repositories.scheme_seats import get_scheme_version_seat_by_seat_id, list_scheme_version_seats
from app.repositories.scheme_versions import get_current_scheme_version
from app.repositories.schemes import get_scheme_record_by_scheme_id
from app.schemas.pricing_diagnostics import (
    PricingCoverageSummaryResponse,
    PricingExplainMatchedRule,
    PricingExplainResponse,
    UnpricedSeatItem,
    UnpricedSeatsResponse,
)
from app.security.auth import require_api_key

router = APIRouter()


def _build_unpriced_reason(*, seat_id: str | None) -> tuple[str, str]:
    if not seat_id:
        return (
            "missing_seat_id",
            "Seat has no seat_id, so price resolution is impossible.",
        )
    return (
        "no_price_rule",
        "No effective price rule was found for this seat.",
    )


@router.get(
    f"{settings.api_v1_prefix}/schemes/{{scheme_id}}/pricing/coverage",
    response_model=PricingCoverageSummaryResponse,
)
async def get_pricing_coverage_summary(
    scheme_id: str,
    role: str = Depends(require_api_key),
):
    scheme = await get_scheme_record_by_scheme_id(scheme_id)
    version = await get_current_scheme_version(
        scheme_id=scheme.scheme_id,
        current_version_number=scheme.current_version_number,
    )
    seats = await list_scheme_version_seats(version.scheme_version_id)

    priced_seats = 0
    unpriced_seats = 0

    for seat in seats:
        if not seat.seat_id:
            unpriced_seats += 1
            continue

        try:
            await find_effective_price_rule(
                scheme_id=scheme.scheme_id,
                seat_id=seat.seat_id,
                group_id=seat.group_id,
                sector_id=seat.sector_id,
            )
            priced_seats += 1
        except Exception:
            unpriced_seats += 1

    total_seats = len(seats)
    coverage_percent = round((priced_seats / total_seats) * 100, 2) if total_seats else 0.0

    return PricingCoverageSummaryResponse(
        scheme_id=scheme.scheme_id,
        scheme_version_id=version.scheme_version_id,
        total_seats=total_seats,
        priced_seats=priced_seats,
        unpriced_seats=unpriced_seats,
        coverage_percent=coverage_percent,
    )


@router.get(
    f"{settings.api_v1_prefix}/schemes/{{scheme_id}}/pricing/unpriced-seats",
    response_model=UnpricedSeatsResponse,
)
async def get_unpriced_seats(
    scheme_id: str,
    role: str = Depends(require_api_key),
):
    scheme = await get_scheme_record_by_scheme_id(scheme_id)
    version = await get_current_scheme_version(
        scheme_id=scheme.scheme_id,
        current_version_number=scheme.current_version_number,
    )
    seats = await list_scheme_version_seats(version.scheme_version_id)

    items: list[UnpricedSeatItem] = []

    for seat in seats:
        if seat.seat_id:
            try:
                await find_effective_price_rule(
                    scheme_id=scheme.scheme_id,
                    seat_id=seat.seat_id,
                    group_id=seat.group_id,
                    sector_id=seat.sector_id,
                )
                continue
            except Exception:
                pass

        reason_code, reason_message = _build_unpriced_reason(seat_id=seat.seat_id)
        items.append(
            UnpricedSeatItem(
                seat_record_id=seat.seat_record_id,
                seat_id=seat.seat_id,
                element_id=seat.element_id,
                sector_id=seat.sector_id,
                group_id=seat.group_id,
                row_label=seat.row_label,
                seat_number=seat.seat_number,
                reason_code=reason_code,
                reason_message=reason_message,
            )
        )

    return UnpricedSeatsResponse(
        scheme_id=scheme.scheme_id,
        scheme_version_id=version.scheme_version_id,
        total=len(items),
        items=items,
    )


@router.get(
    f"{settings.api_v1_prefix}/schemes/{{scheme_id}}/pricing/explain/{{seat_id}}",
    response_model=PricingExplainResponse,
)
async def explain_pricing_for_seat(
    scheme_id: str,
    seat_id: str,
    role: str = Depends(require_api_key),
):
    scheme = await get_scheme_record_by_scheme_id(scheme_id)
    version = await get_current_scheme_version(
        scheme_id=scheme.scheme_id,
        current_version_number=scheme.current_version_number,
    )
    seat = await get_scheme_version_seat_by_seat_id(
        scheme_version_id=version.scheme_version_id,
        seat_id=seat_id,
    )

    if not seat.seat_id:
        reason_code, reason_message = _build_unpriced_reason(seat_id=seat.seat_id)
        return PricingExplainResponse(
            scheme_id=scheme.scheme_id,
            scheme_version_id=version.scheme_version_id,
            seat_id=seat.seat_id,
            element_id=seat.element_id,
            sector_id=seat.sector_id,
            group_id=seat.group_id,
            row_label=seat.row_label,
            seat_number=seat.seat_number,
            has_price=False,
            reason_code=reason_code,
            reason_message=reason_message,
            matched_rule=None,
        )

    try:
        matched_rule_level, rule = await find_effective_price_rule(
            scheme_id=scheme.scheme_id,
            seat_id=seat.seat_id,
            group_id=seat.group_id,
            sector_id=seat.sector_id,
        )
        return PricingExplainResponse(
            scheme_id=scheme.scheme_id,
            scheme_version_id=version.scheme_version_id,
            seat_id=seat.seat_id,
            element_id=seat.element_id,
            sector_id=seat.sector_id,
            group_id=seat.group_id,
            row_label=seat.row_label,
            seat_number=seat.seat_number,
            has_price=True,
            reason_code="ok",
            reason_message="Effective price rule resolved successfully.",
            matched_rule=PricingExplainMatchedRule(
                matched_rule_level=matched_rule_level,
                matched_target_ref=rule["target_ref"],
                pricing_category_id=rule["pricing_category_id"],
                amount=str(rule["amount"]),
                currency=rule["currency"],
            ),
        )
    except Exception:
        reason_code, reason_message = _build_unpriced_reason(seat_id=seat.seat_id)
        return PricingExplainResponse(
            scheme_id=scheme.scheme_id,
            scheme_version_id=version.scheme_version_id,
            seat_id=seat.seat_id,
            element_id=seat.element_id,
            sector_id=seat.sector_id,
            group_id=seat.group_id,
            row_label=seat.row_label,
            seat_number=seat.seat_number,
            has_price=False,
            reason_code=reason_code,
            reason_message=reason_message,
            matched_rule=None,
        )