import { randomUUID } from "node:crypto";
import { isRequestTimestampFresh, verifyHashedToken } from "@minecraft-account-manager/auth";
import { problemDetails, velocityConnectionRequestSchema } from "@minecraft-account-manager/contracts";
import { events, minecraftAccounts, pluginCredentials, pluginRequests } from "@minecraft-account-manager/database";
import { and, eq, isNull, lt } from "drizzle-orm";
import { NextResponse } from "next/server";
import { db } from "@/lib/database";
import { isUniqueConstraintViolation } from "@/lib/database-errors";
import { logger } from "@/lib/logger";
import { problemInstance, problemResponse } from "@/lib/problem-response";

const MAX_CLOCK_SKEW_MS = 45_000;

function methodNotAllowed(request: Request) {
  const response = problemResponse(problemDetails(
    "urn:error:method-not-allowed",
    "Method not allowed",
    405,
    "This endpoint only accepts POST requests.",
    problemInstance(request),
  ));
  response.headers.set("allow", "POST");
  return response;
}

export const GET = methodNotAllowed;
export const PUT = methodNotAllowed;
export const PATCH = methodNotAllowed;
export const DELETE = methodNotAllowed;

export async function POST(request: Request) {
  const instance = problemInstance(request);
  const authorization = request.headers.get("authorization") ?? "";
  const token = authorization.startsWith("Bearer ") ? authorization.slice(7).trim() : "";
  if (!token) return problemResponse(problemDetails(
    "urn:error:unauthorized",
    "Unauthorized",
    401,
    "A valid Velocity server credential is required.",
    instance,
  ));

  const mediaType = request.headers.get("content-type")?.split(";", 1)[0]?.trim().toLowerCase();
  if (mediaType !== "application/json") return problemResponse(problemDetails(
    "urn:error:unsupported-media-type",
    "Unsupported media type",
    415,
    "Velocity connection reports must use application/json.",
    instance,
  ));

  const parsed = velocityConnectionRequestSchema.safeParse(await request.json().catch(() => null));
  if (!parsed.success) return problemResponse(problemDetails(
    "urn:error:invalid-velocity-connection-request",
    "Invalid Velocity connection report",
    400,
    "The request body does not match the required Velocity connection contract.",
    instance,
    { issues: parsed.error.issues.map((issue) => ({ path: issue.path.join("."), message: issue.message, code: issue.code })) },
  ));

  const input = parsed.data;
  const occurredAt = new Date(input.occurredAt);
  if (!isRequestTimestampFresh(occurredAt, new Date(), MAX_CLOCK_SKEW_MS)) return problemResponse(problemDetails(
    "urn:error:expired-velocity-connection-request",
    "Expired Velocity connection report",
    401,
    "The request timestamp is outside the allowed clock-skew window.",
    instance,
  ));

  const [credential] = await db
    .select({ secretHash: pluginCredentials.secretHash })
    .from(pluginCredentials)
    .where(and(eq(pluginCredentials.serverId, input.serverId), isNull(pluginCredentials.revokedAt)))
    .limit(1);
  if (!credential || !verifyHashedToken(token, credential.secretHash)) return problemResponse(problemDetails(
    "urn:error:unauthorized",
    "Unauthorized",
    401,
    "The Velocity server credential is invalid or revoked.",
    instance,
  ));

  try {
    const recorded = await db.transaction(async (tx) => {
      await tx.delete(pluginRequests).where(lt(pluginRequests.expiresAt, new Date()));
      await tx.insert(pluginRequests).values({
        requestId: input.requestId,
        serverId: input.serverId,
        receivedAt: new Date(),
        expiresAt: new Date(Date.now() + 5 * 60_000),
      });
      const [account] = await tx
        .select({ id: minecraftAccounts.id, userId: minecraftAccounts.userId })
        .from(minecraftAccounts)
        .where(and(eq(minecraftAccounts.minecraftUuid, input.minecraftUuid), isNull(minecraftAccounts.deletedAt)))
        .limit(1);
      if (!account) return false;

      await tx.insert(events).values({
        id: randomUUID(),
        source: `/velocity/${input.serverId}`,
        type: "games.minecraft.account-manager.game.player.connected",
        subject: `minecraft-account/${account.id}`,
        time: occurredAt,
        actorUserId: account.userId,
        correlationId: input.requestId,
        data: {
          username: input.username,
          minecraftUuid: input.minecraftUuid,
          serverId: input.serverId,
        },
      });
      return true;
    });
    if (!recorded) return problemResponse(problemDetails(
      "urn:error:unknown-minecraft-account",
      "Unknown Minecraft account",
      404,
      "The connected Minecraft account is no longer registered.",
      instance,
    ));
    return new NextResponse(null, { status: 204 });
  } catch (error) {
    if (isUniqueConstraintViolation(error, "plugin_requests_pkey")) return problemResponse(problemDetails(
      "urn:error:replayed-velocity-connection-request",
      "Velocity request replayed",
      409,
      "This Velocity request ID has already been processed.",
      instance,
    ));
    logger.error({ err: error, event: "velocity.connection_report_failed" }, "Failed to record a confirmed Velocity connection");
    return problemResponse(problemDetails(
      "urn:error:service-unavailable",
      "Service unavailable",
      503,
      "The connection report could not be recorded.",
      instance,
    ));
  }
}