from __future__ import annotations

from decimal import Decimal
from typing import Any

from .models import EconomicsSnapshot, PricingModel

from ._repo_root import ensure_repo_root_on_syspath

ensure_repo_root_on_syspath()

from adaptive_pricing_core.boundary_engine import (  # noqa: E402
    BoundaryPolicy,
    PricingConfiguration,
    validate_pricing_configuration,
)


def _usage_unit_cost(records: list[dict[str, Any]], period: str) -> Decimal:
    period_rows = [row for row in records if row.get("period") == period]
    total_tokens = sum(Decimal(str(row.get("tokens", "0"))) for row in period_rows)
    total_cost = sum(Decimal(str(row.get("cost_eur", "0"))) for row in period_rows)
    if total_tokens <= Decimal("0"):
        return Decimal("0")
    return total_cost / total_tokens


def _total_usage_units(records: list[dict[str, Any]], period: str) -> Decimal:
    return sum(Decimal(str(row.get("tokens", "0"))) for row in records if row.get("period") == period)


def build_boundary_policy(snapshot: EconomicsSnapshot) -> BoundaryPolicy:
    return BoundaryPolicy(
        minimum_margin_pct=Decimal("0"),
        target_margin_pct=Decimal("15"),
        max_payment_fee_pct=Decimal("10"),
        max_expected_usage_variance_pct=Decimal("50"),
        approval_discount_pct=Decimal("10"),
        max_discount_pct=Decimal("25"),
        minimum_contract_duration_for_discount_months=3,
        minimum_turnover_multiple_for_discount=Decimal("1"),
        minimum_prepayment_months_for_discount=Decimal("1"),
    )


def build_boundary_validation(
    snapshot: EconomicsSnapshot,
    models: list[PricingModel],
    usage_records: list[dict[str, Any]],
    segment: str | None = None,
) -> dict[str, Any]:
    fee_rate_pct = Decimal("0")
    if snapshot.monthly_revenue > Decimal("0"):
        fee_rate_pct = (
            snapshot.monthly_payment_processing_cost / snapshot.monthly_revenue
        ) * Decimal("100")

    unit_cost = _usage_unit_cost(usage_records, snapshot.period)
    usage_units = _total_usage_units(usage_records, snapshot.period)
    direct_usage_cost = sum(
        Decimal(str(row.get("cost_eur", "0")))
        for row in usage_records
        if row.get("period") == snapshot.period
    )
    allocated_fixed_cost = (
        snapshot.monthly_infrastructure_cost / snapshot.active_members
        if snapshot.active_members
        else snapshot.monthly_infrastructure_cost
    )

    policy = build_boundary_policy(snapshot)
    model_results = []
    for model in models:
        has_usage_component = any(component.kind == "usage" for component in model.charge_components)
        configuration = PricingConfiguration(
            model=model,
            segment=segment or (model.eligibility[0] if model.eligibility else None),
            expected_usage_units=usage_units if has_usage_component else Decimal("0"),
            expected_usage_variance_pct=Decimal("25"),
            allocated_fixed_cost=allocated_fixed_cost,
            direct_cost_amount=Decimal("0") if has_usage_component else direct_usage_cost,
            unit_cost=unit_cost if has_usage_component else Decimal("0"),
            payment_fee_rate_pct=fee_rate_pct,
        )
        model_results.append(validate_pricing_configuration(configuration, policy))

    return {
        "period": snapshot.period,
        "policy": policy,
        "assumptions": {
            "segment": segment or "model-default-eligibility",
            "observed_usage_units": usage_units,
            "observed_usage_unit_cost": unit_cost,
            "direct_usage_cost_for_flat_models": direct_usage_cost,
            "allocated_fixed_cost_per_member": allocated_fixed_cost,
            "payment_fee_rate_pct": fee_rate_pct,
            "expected_usage_variance_pct": Decimal("25"),
        },
        "model_results": model_results,
        "notes": [
            "This MVP policy uses current observatory economics and conservative defaults rather than a seller-specific governance file.",
            "Self-serve discounts above 10% require approval; discounts above 25% are rejected.",
            "Term-only concessions require at least a 3-month contract to count as meaningful commitment support.",
        ],
    }