from __future__ import annotations

from decimal import Decimal
from pathlib import Path

from adaptive_pricing_core.boundary_engine import (
    BoundaryPolicy,
    CommitmentTerms,
    PricingConfiguration,
    validate_pricing_configuration,
)
from observatory.load import load_pricing_models

DATA_DIR = Path(__file__).resolve().parent.parent / "data"


def _model(model_id: str):
    return next(item for item in load_pricing_models(DATA_DIR) if item.id == model_id)


def test_commitment_backed_discount_is_accepted_when_economics_stay_strong() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("membership-plus-overage"),
            segment="coulomb-social-members",
            expected_usage_units=Decimal("100200"),
            expected_usage_variance_pct=Decimal("25"),
            allocated_fixed_cost=Decimal("2.00"),
            unit_cost=Decimal("0.00000125"),
            payment_fee_rate_pct=Decimal("5"),
            usage_unit_price=Decimal("0.0015"),
            commitment_terms=CommitmentTerms(
                contract_duration_months=6,
                minimum_monthly_turnover=Decimal("9.30"),
            ),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "accepted"
    assert result.valid is True
    assert result.requires_approval is False
    commitment_result = next(
        item for item in result.constraints if item.id == "commitment-backed-concession"
    )
    assert commitment_result.status == "pass"
    assert "minimum_monthly_turnover" in commitment_result.details["signals"]


def test_discount_without_commitment_is_rejected() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("membership-plus-overage"),
            segment="coulomb-social-members",
            expected_usage_units=Decimal("100200"),
            expected_usage_variance_pct=Decimal("25"),
            allocated_fixed_cost=Decimal("2.00"),
            unit_cost=Decimal("0.00000125"),
            payment_fee_rate_pct=Decimal("5"),
            usage_unit_price=Decimal("0.0015"),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "rejected"
    assert result.valid is False
    failing_ids = {
        item.id for item in result.constraints if item.status == "fail" and item.severity == "hard"
    }
    assert "commitment-backed-concession" in failing_ids


def test_weak_commitment_trade_is_rejected() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("membership-plus-overage"),
            segment="coulomb-social-members",
            expected_usage_units=Decimal("100200"),
            expected_usage_variance_pct=Decimal("25"),
            allocated_fixed_cost=Decimal("2.00"),
            unit_cost=Decimal("0.00000125"),
            payment_fee_rate_pct=Decimal("5"),
            usage_unit_price=Decimal("0.0015"),
            commitment_terms=CommitmentTerms(
                contract_duration_months=2,
                minimum_monthly_turnover=Decimal("9.00"),
            ),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "rejected"
    commitment_result = next(
        item for item in result.constraints if item.id == "commitment-backed-concession"
    )
    assert commitment_result.status == "fail"


def test_large_but_supported_concession_requires_approval() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("flat-899-eur-monthly"),
            segment="coulomb-social-members",
            allocated_fixed_cost=Decimal("1.00"),
            payment_fee_rate_pct=Decimal("5"),
            access_fee_amount=Decimal("7.50"),
            commitment_terms=CommitmentTerms(
                contract_duration_months=6,
                minimum_monthly_turnover=Decimal("8.00"),
            ),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "requires_approval"
    assert result.valid is True
    assert result.requires_approval is True
    review_ids = {item.id for item in result.constraints if item.status == "review"}
    assert "discount-approval-threshold" in review_ids


def test_zero_usage_flat_configuration_can_pass() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("flat-899-eur-monthly"),
            segment="coulomb-social-members",
            expected_usage_units=Decimal("0"),
            expected_usage_variance_pct=Decimal("0"),
            allocated_fixed_cost=Decimal("3.00"),
            payment_fee_rate_pct=Decimal("5"),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "accepted"
    assert result.metrics.billable_usage_units == Decimal("0")


def test_high_fee_configuration_is_rejected() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("flat-899-eur-monthly"),
            segment="coulomb-social-members",
            allocated_fixed_cost=Decimal("1.00"),
            payment_fee_rate_pct=Decimal("30"),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "rejected"
    payment_fee_result = next(item for item in result.constraints if item.id == "payment-fee-limit")
    assert payment_fee_result.status == "fail"


def test_unprofitable_configuration_is_rejected() -> None:
    result = validate_pricing_configuration(
        PricingConfiguration(
            model=_model("flat-899-eur-monthly"),
            segment="coulomb-social-members",
            allocated_fixed_cost=Decimal("10.00"),
            payment_fee_rate_pct=Decimal("5"),
        ),
        BoundaryPolicy(),
    )

    assert result.decision == "rejected"
    assert result.metrics.monthly_margin < Decimal("0")
    assert any(item.id == "cost-floor-coverage" and item.status == "fail" for item in result.constraints)