import { z } from "zod";

export const MAX_MCP_HEADERS = 8;
const reserved = new Set([
  "host",
  "content-length",
  "content-type",
  "accept",
  "connection",
  "transfer-encoding",
  "upgrade",
  "origin",
  "referer",
]);
export const mcpHeaderName = z
  .string()
  .trim()
  .toLowerCase()
  .min(1)
  .max(100)
  .regex(/^[!#$%&'*+.^_`|~0-9a-z-]+$/)
  .refine(
    (name) =>
      !reserved.has(name) &&
      !name.startsWith("sec-") &&
      !name.startsWith("mcp-"),
  );
export const mcpHeaders = z
  .array(
    z.strictObject({
      name: mcpHeaderName,
      value: z
        .string()
        .trim()
        .min(1)
        .max(4096)
        .regex(/^[\x20-\x7e]+$/),
    }),
  )
  .max(MAX_MCP_HEADERS)
  .refine(
    (headers) =>
      new Set(headers.map((header) => header.name)).size === headers.length,
  )
  .refine(
    (headers) =>
      headers.reduce(
        (bytes, header) => bytes + header.name.length + header.value.length,
        0,
      ) <= 16384,
  );
export type McpHeader = z.infer<typeof mcpHeaders>[number];