import type { DeviceConfig, DeviceStatus } from "../types.js";
import type { HomeAssistantClient } from "./client.js";

function normalizeHaValue(kind: DeviceConfig["kind"], state: string): number | null {
  if (kind === "switch") {
    if (state === "on") return 1;
    if (state === "off") return 0;
    return null;
  }
  const n = Number(state);
  return Number.isFinite(n) ? n : null;
}

/** True when both directions are driven by custom endpoints rather than Home Assistant. */
function isExternallyControlled(device: DeviceConfig): boolean {
  return device.enableUrl !== null && device.disableUrl !== null;
}

async function callEndpoint(url: string): Promise<void> {
  const res = await fetch(url, { method: "POST" });
  if (!res.ok) {
    throw new Error(`custom endpoint request failed: POST ${url} -> ${res.status} ${await res.text()}`);
  }
}

export async function getDeviceStatus(
  ha: HomeAssistantClient,
  device: DeviceConfig,
  shed: boolean,
  lastChangedAt: string | null,
): Promise<DeviceStatus> {
  // Externally controlled devices have no Home Assistant entity to poll; state is
  // whatever we last commanded via the custom endpoints.
  if (isExternallyControlled(device)) {
    return {
      ...device,
      currentValue: shed ? (device.kind === "switch" ? 0 : device.minValue) : device.kind === "switch" ? 1 : device.maxValue,
      shed,
      lastChangedAt,
      available: true,
    };
  }
  try {
    const haState = await ha.getState(device.entityId);
    return {
      ...device,
      currentValue: normalizeHaValue(device.kind, haState.state),
      shed,
      lastChangedAt,
      available: haState.state !== "unavailable" && haState.state !== "unknown",
    };
  } catch {
    return {
      ...device,
      currentValue: null,
      shed,
      lastChangedAt,
      available: false,
    };
  }
}

/** Sheds (reduces load of) a device: turns a switch off, or lowers a number to its floor. */
export async function shedDevice(ha: HomeAssistantClient, device: DeviceConfig): Promise<void> {
  if (device.disableUrl) {
    await callEndpoint(device.disableUrl);
    return;
  }
  if (device.kind === "switch") {
    await ha.setSwitch(device.entityId, false);
  } else {
    await ha.setNumber(device.entityId, device.minValue);
  }
}

/** Restores a device to its normal operating value. */
export async function restoreDevice(ha: HomeAssistantClient, device: DeviceConfig): Promise<void> {
  if (device.enableUrl) {
    await callEndpoint(device.enableUrl);
    return;
  }
  if (device.kind === "switch") {
    await ha.setSwitch(device.entityId, true);
  } else {
    await ha.setNumber(device.entityId, device.maxValue);
  }
}