"use server";

import config from "@payload-config";
import { getPayload } from "payload";
import type { AssignmentTransfer } from "@/payload-types";
import { isPayloadUser } from "@/utils/access-control/isPayloadUser";
import {
  appealTransfer as appealTransferCore,
  cancelTransfer as cancelTransferCore,
  createTransferRequest,
  recordTransferDecision,
  resolveAppeal as resolveAppealCore,
} from "@/lib/transfers";

export interface ActionResult<T = undefined> {
  readonly success: boolean;
  readonly error?: string;
  readonly data?: T;
}

/**
 * Web action mapping: requestTransfer → createTransferRequest, approveTransfer and
 * rejectTransfer → recordTransferDecision, appealTransfer → appealTransfer,
 * resolveAppeal → resolveAppeal, and cancelTransfer → cancelTransfer. The authenticated
 * user supplies each core function's actorUserId/requesterId.
 */

async function authenticate() {
  const payloadConfig = await config;
  const payload = await getPayload({ config: payloadConfig });
  const { headers } = await import("next/headers");
  const hdrs = await headers();
  const { user } = await payload.auth({ headers: hdrs, canSetHeaders: false });

  if (!isPayloadUser(user)) {
    throw new Error("Unauthorized");
  }

  return { payload, user };
}

function actionFailure<T>(caughtError: unknown): ActionResult<T> {
  const message = caughtError instanceof Error ? caughtError.message : "Unknown error";
  return {
    success: false,
    error: message === "Unauthorized" ? "You must be logged in." : message,
  };
}

export async function requestTransfer(input: {
  readonly fromAssignmentId: number;
  readonly toAssignmentId: number;
  readonly note?: string;
}): Promise<ActionResult<AssignmentTransfer>> {
  try {
    const { payload, user } = await authenticate();
    const transfer = await createTransferRequest(payload, {
      requesterId: user.id,
      fromAssignmentId: input.fromAssignmentId,
      toAssignmentId: input.toAssignmentId,
      ...(input.note !== undefined ? { note: input.note } : {}),
    });
    return { success: true, data: transfer };
  } catch (caughtError) {
    return actionFailure<AssignmentTransfer>(caughtError);
  }
}

export async function approveTransfer(
  requestId: number,
  side: "from" | "to",
): Promise<ActionResult<AssignmentTransfer>> {
  try {
    const { payload, user } = await authenticate();
    const transfer = await recordTransferDecision(payload, {
      requestId,
      side,
      decision: "approved",
      actorUserId: user.id,
    });
    return { success: true, data: transfer };
  } catch (caughtError) {
    return actionFailure<AssignmentTransfer>(caughtError);
  }
}

export async function rejectTransfer(
  requestId: number,
  side: "from" | "to",
  reason: string,
): Promise<ActionResult<AssignmentTransfer>> {
  try {
    const { payload, user } = await authenticate();
    const transfer = await recordTransferDecision(payload, {
      requestId,
      side,
      decision: "rejected",
      reason,
      actorUserId: user.id,
    });
    return { success: true, data: transfer };
  } catch (caughtError) {
    return actionFailure<AssignmentTransfer>(caughtError);
  }
}

export async function appealTransfer(
  requestId: number,
  note?: string,
): Promise<ActionResult<AssignmentTransfer>> {
  try {
    const { payload, user } = await authenticate();
    const transfer = await appealTransferCore(payload, {
      requestId,
      actorUserId: user.id,
      ...(note !== undefined ? { note } : {}),
    });
    return { success: true, data: transfer };
  } catch (caughtError) {
    return actionFailure<AssignmentTransfer>(caughtError);
  }
}

export async function resolveAppeal(
  requestId: number,
  approve: boolean,
  note?: string,
): Promise<ActionResult<AssignmentTransfer>> {
  try {
    const { payload, user } = await authenticate();
    const transfer = await resolveAppealCore(payload, {
      requestId,
      approve,
      actorUserId: user.id,
      ...(note !== undefined ? { note } : {}),
    });
    return { success: true, data: transfer };
  } catch (caughtError) {
    return actionFailure<AssignmentTransfer>(caughtError);
  }
}

export async function cancelTransfer(
  requestId: number,
): Promise<ActionResult<AssignmentTransfer>> {
  try {
    const { payload, user } = await authenticate();
    const transfer = await cancelTransferCore(payload, {
      requestId,
      actorUserId: user.id,
    });
    return { success: true, data: transfer };
  } catch (caughtError) {
    return actionFailure<AssignmentTransfer>(caughtError);
  }
}