from __future__ import annotations

from datetime import time as time_
from typing import Literal

from fastapi import APIRouter
from pydantic import BaseModel

from app.costing.tariff_models import (
    ALL_DAYS,
    ConditionalDiscount,
    FeedInComponent,
    TariffPlan,
    TieredFeedIn,
    TimeWindow,
    UsageComponent,
)
from app.db.repositories import get_current_plan, get_household_config, set_current_plan
from app.db.session import get_session

router = APIRouter(prefix="/api/settings", tags=["settings"])


class TouPeriodIn(BaseModel):
    label: str
    rate_c_per_kwh: float
    start_time: time_
    end_time: time_
    days: list[str] | None = None  # None = every day


class CurrentPlanIn(BaseModel):
    retailer_name: str
    plan_name: str
    supply_charge_dollars_per_day: float
    tariff_type: Literal["flat", "time_of_use"]
    flat_rate_c_per_kwh: float | None = None
    tou_periods: list[TouPeriodIn] | None = None
    feed_in_type: Literal["flat", "tiered"] = "flat"
    feed_in_tariff_c_per_kwh: float = 0.0
    tiered_daily_threshold_kwh: float | None = None
    tiered_rate_below_c_per_kwh: float | None = None
    tiered_rate_above_c_per_kwh: float | None = None
    discount_percent: float | None = None  # a discount already baked into the plan you signed up for


class HouseholdIn(BaseModel):
    distributor: str
    postcode: str
    isolarcloud_ps_id: str | None = None


def _plan_from_form(form: CurrentPlanIn) -> TariffPlan:
    if form.tariff_type == "flat":
        if form.flat_rate_c_per_kwh is None:
            raise ValueError("flat_rate_c_per_kwh is required for a flat tariff")
        usage_components = [UsageComponent(label="Usage", rate_c_per_kwh=form.flat_rate_c_per_kwh)]
    else:
        if not form.tou_periods:
            raise ValueError("tou_periods is required for a time_of_use tariff")
        usage_components = [
            UsageComponent(
                label=p.label,
                rate_c_per_kwh=p.rate_c_per_kwh,
                time_windows=[TimeWindow(days=p.days or list(ALL_DAYS), start_time=p.start_time, end_time=p.end_time)],
            )
            for p in form.tou_periods
        ]

    discounts = []
    if form.discount_percent:
        discounts.append(
            ConditionalDiscount(description="Plan discount", percent=form.discount_percent, applies_to="usage", auto_apply=True)
        )

    feed_in_tariffs: list[FeedInComponent] = []
    tiered_feed_in: TieredFeedIn | None = None
    if form.feed_in_type == "tiered":
        if form.tiered_daily_threshold_kwh is None or form.tiered_rate_below_c_per_kwh is None or form.tiered_rate_above_c_per_kwh is None:
            raise ValueError("tiered_daily_threshold_kwh, tiered_rate_below_c_per_kwh and tiered_rate_above_c_per_kwh are required for a tiered feed-in tariff")
        tiered_feed_in = TieredFeedIn(
            daily_threshold_kwh=form.tiered_daily_threshold_kwh,
            rate_below_c_per_kwh=form.tiered_rate_below_c_per_kwh,
            rate_above_c_per_kwh=form.tiered_rate_above_c_per_kwh,
        )
    else:
        feed_in_tariffs = [FeedInComponent(label="Feed-in tariff", rate_c_per_kwh=form.feed_in_tariff_c_per_kwh)]

    return TariffPlan(
        plan_id="current-plan",
        retailer=form.retailer_name,
        plan_name=form.plan_name,
        supply_charge_c_per_day=form.supply_charge_dollars_per_day * 100,
        usage_components=usage_components,
        feed_in_tariffs=feed_in_tariffs,
        tiered_feed_in=tiered_feed_in,
        discounts=discounts,
        source="manual",
    )


@router.get("/current-plan")
def get_current_plan_route() -> dict | None:
    with get_session() as session:
        plan = get_current_plan(session)
    if plan is None:
        return None
    return plan.model_dump(mode="json")


@router.post("/current-plan")
def save_current_plan(form: CurrentPlanIn) -> dict:
    plan = _plan_from_form(form)
    with get_session() as session:
        set_current_plan(session, form.retailer_name, form.plan_name, plan)
    return plan.model_dump(mode="json")


@router.get("/household")
def get_household() -> dict:
    with get_session() as session:
        cfg = get_household_config(session)
        return {"distributor": cfg.distributor, "postcode": cfg.postcode, "isolarcloud_ps_id": cfg.isolarcloud_ps_id}


@router.post("/household")
def save_household(form: HouseholdIn) -> dict:
    with get_session() as session:
        cfg = get_household_config(session)
        cfg.distributor = form.distributor
        cfg.postcode = form.postcode
        if form.isolarcloud_ps_id is not None:
            cfg.isolarcloud_ps_id = form.isolarcloud_ps_id
        session.flush()
        return {"distributor": cfg.distributor, "postcode": cfg.postcode, "isolarcloud_ps_id": cfg.isolarcloud_ps_id}