import { sql } from "drizzle-orm";
import { NextResponse } from "next/server";
import { z } from "zod";
import { auth } from "@/app/(auth)/auth";
import { db } from "@/lib/db";
import { clientPerformanceEvent } from "@/lib/db/schema";

export const runtime = "nodejs";
export const maxDuration = 10;

const SLOW_EVENT_MIN_DURATION_MS = 120;
const RATE_LIMIT_WINDOW_MS = 60_000;
const RATE_LIMIT_MAX_EVENTS = 20;
const TEXT_MAX_LENGTH = 256;

const allowedSections = [
  "brand",
  "style",
  "mode",
  "materials",
  "generate",
  "references",
  "results",
  "unknown",
] as const;

const eventSchema = z.object({
  eventType: z.string().trim().min(1).max(64),
  durationMs: z.coerce.number().finite().min(0).max(120_000),
  blockingDurationMs: z.coerce.number().finite().min(0).max(120_000).optional(),
  section: z.enum(allowedSections).optional(),
  action: z.string().trim().max(64).optional(),
  domNodeCount: z.coerce.number().int().min(0).max(1_000_000).optional(),
  visibleImageCount: z.coerce.number().int().min(0).max(100_000).optional(),
  loadedImageCount: z.coerce.number().int().min(0).max(100_000).optional(),
  viewport: z
    .object({
      width: z.coerce.number().finite().min(0).max(20_000).optional(),
      height: z.coerce.number().finite().min(0).max(20_000).optional(),
      dpr: z.coerce.number().finite().min(0).max(8).optional(),
    })
    .optional(),
  browser: z.string().trim().max(128).optional(),
  path: z.string().trim().max(TEXT_MAX_LENGTH).optional(),
  projectId: z.string().trim().max(64).optional().nullable(),
  chatId: z.string().trim().uuid().optional().nullable(),
  timestamp: z.union([z.string(), z.number(), z.date()]).optional(),
});

type RateWindow = {
  windowStart: number;
  count: number;
};

const rateWindows = new Map<string, RateWindow>();

function clampText(value: unknown, maxLength = TEXT_MAX_LENGTH) {
  const normalized = String(value || "").trim();
  if (!normalized) return null;
  return normalized.slice(0, maxLength);
}

function stripPath(value: unknown) {
  const normalized = clampText(value);
  if (!normalized) return null;
  if (/https?:\/\//i.test(normalized)) {
    try {
      return new URL(normalized).pathname.slice(0, TEXT_MAX_LENGTH) || "/";
    } catch {
      return "/";
    }
  }
  return normalized.split("?")[0].split("#")[0].slice(0, TEXT_MAX_LENGTH) || "/";
}

function getRequesterIp(request: Request) {
  const forwarded = request.headers.get("x-forwarded-for");
  const firstForwarded = forwarded?.split(",")[0]?.trim();
  return (
    firstForwarded ||
    request.headers.get("x-real-ip") ||
    request.headers.get("cf-connecting-ip") ||
    "unknown"
  ).slice(0, 64);
}

function isRateLimited(key: string) {
  const now = Date.now();
  const current = rateWindows.get(key);
  if (!current || now - current.windowStart >= RATE_LIMIT_WINDOW_MS) {
    rateWindows.set(key, { windowStart: now, count: 1 });
    return false;
  }
  current.count += 1;
  return current.count > RATE_LIMIT_MAX_EVENTS;
}

function normalizeOccurredAt(value: unknown) {
  if (!value) return new Date();
  const date =
    value instanceof Date
      ? value
      : typeof value === "number"
        ? new Date(value)
        : new Date(String(value));
  return Number.isNaN(date.getTime()) ? new Date() : date;
}

function includesDisallowedPayloadKeys(value: unknown) {
  if (!value || typeof value !== "object") return false;
  const keys = Object.keys(value as Record<string, unknown>).map((key) => key.toLowerCase());
  return keys.some((key) =>
    [
      "prompt",
      "image",
      "imageurl",
      "imageurls",
      "thumbnailurl",
      "originalurl",
      "url",
      "urls",
      "input",
      "text",
      "content",
    ].includes(key)
  );
}

async function maybePruneOldEvents() {
  if (Math.random() > 0.01) return;
  await db.execute(sql`
    DELETE FROM "ClientPerformanceEvent"
    WHERE "createdAt" < NOW() - INTERVAL '14 days'
  `);
}

export async function POST(request: Request) {
  try {
    const contentType = request.headers.get("content-type") || "";
    if (!contentType.toLowerCase().includes("application/json")) {
      return NextResponse.json({ ok: true });
    }

    const raw = await request.json().catch(() => null);
    if (!raw || typeof raw !== "object" || includesDisallowedPayloadKeys(raw)) {
      return NextResponse.json({ ok: true });
    }

    const parsed = eventSchema.safeParse(raw);
    if (!parsed.success) {
      return NextResponse.json({ ok: true });
    }

    const event = parsed.data;
    if (event.durationMs < SLOW_EVENT_MIN_DURATION_MS) {
      return NextResponse.json({ ok: true });
    }

    const session = await auth().catch(() => null);
    const requesterIp = getRequesterIp(request);
    const rateKey = `${session?.user?.id || "anon"}:${requesterIp}`;
    if (isRateLimited(rateKey)) {
      return NextResponse.json({ ok: true });
    }

    await maybePruneOldEvents().catch((error) => {
      console.warn("[ClientPerformance] prune failed", error);
    });

    await db.insert(clientPerformanceEvent).values({
      userId: session?.user?.id || null,
      chatId: event.chatId || null,
      projectId: clampText(event.projectId, 64),
      eventType: clampText(event.eventType, 64) || "unknown",
      section: event.section || "unknown",
      action: clampText(event.action, 64),
      path: stripPath(event.path),
      durationMs: Math.round(event.durationMs),
      blockingDurationMs: Math.round(event.blockingDurationMs || 0),
      domNodeCount: event.domNodeCount || 0,
      visibleImageCount: event.visibleImageCount || 0,
      loadedImageCount: event.loadedImageCount || 0,
      viewport: event.viewport || null,
      browser: clampText(event.browser, 128),
      metadata: {
        source: "agent-style-client",
      },
      requesterIp,
      requesterUserAgent: clampText(request.headers.get("user-agent"), 512),
      occurredAt: normalizeOccurredAt(event.timestamp),
    });

    return NextResponse.json({ ok: true });
  } catch (error) {
    console.error("[ClientPerformance] failed to record agent style event:", error);
    return NextResponse.json({ ok: true });
  }
}