import {z} from 'zod'

export type McpJsonRpcRequest = {jsonrpc: '2.0', id?: (string | null | number) | undefined, method: string, params?: {[key: string]: unknown} | undefined};

export type CreateApiMcpArgs = {Accept: string, 'MCP-Protocol-Version'?: string | undefined, Origin?: string | undefined, body: McpJsonRpcRequest};

export type CreateApiMcpOptions = {baseUrl?: string | undefined, McpOAuth?: string | undefined, fetch?: typeof fetch | undefined};

export const mcpJsonRpcResponse = z.object({jsonrpc: z.literal("2.0"), id: z.union([z.string().nullable(), z.number()]).optional(), result: z.record(z.string(), z.unknown()).optional(), error: z.record(z.string(), z.unknown()).optional()});

export const validateResponse = async <Output>(
  schema: {
    readonly '~standard': {
      readonly validate: (value: unknown) => ({ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }) | Promise<{ readonly value: Output; readonly issues?: undefined } | { readonly issues: ReadonlyArray<{ readonly message: string; readonly path?: ReadonlyArray<PropertyKey | { readonly key: PropertyKey }> | undefined }> }>
    }
  },
  value: unknown
): Promise<Output> => {
  const result = await schema['~standard'].validate(value)

  if (result.issues !== undefined) {
    const detail = result.issues
      .map(({ message, path }) =>
        path?.length
          ? `${path.map((segment) => String(typeof segment === 'object' ? segment.key : segment)).join('.')}: ${message}`
          : message
      )
      .join('; ')

    throw new Error(`Response does not match the schema: ${detail}`, { cause: { issues: result.issues } })
  }

  return result.value
};

/**
 * Streamable HTTP JSON-RPC endpoint for remote MCP clients.
 * 
 * POST /mcp
 */
export const createApiMcp = async (args: CreateApiMcpArgs, options?: CreateApiMcpOptions) => {
const {baseUrl = "https://api.traxy.ai/api/v1", fetch: fetchFn = fetch, McpOAuth} = options ?? {}

const query = new URLSearchParams()
const headers = new Headers()
headers.set('content-type', "application/json")
headers.set('accept', "application/json")

if (args.Accept != null) headers.set("Accept", String(args.Accept))
if (args['MCP-Protocol-Version'] != null) headers.set("MCP-Protocol-Version", String(args['MCP-Protocol-Version']))
if (args.Origin != null) headers.set("Origin", String(args.Origin))
if (McpOAuth !== undefined) headers.set('authorization', `Bearer ${McpOAuth}`)

const url = `${baseUrl.replace(/\/+$/, '')}/mcp${query.size > 0 ? `?${query}` : ''}`

const res = await fetchFn(url, {method: "POST", headers, body: JSON.stringify(args.body)})

if (!res.ok) throw new Error(`Request failed with status ${res.status}`, {cause: {status: res.status, body: await res.text()}})

return validateResponse(mcpJsonRpcResponse, await res.json())
};