import {z} from 'zod'

export type GetApiBuyValidateArgs = {url: string, schema: string, pointer?: string | undefined};

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

export const getApiBuyValidateResponse = z.object({ok: z.boolean(), url: z.string(), status: z.number().int().optional(), text: z.string().optional(), fetchedAt: z.string().optional(), data: z.object({valid: z.boolean().optional(), errorCount: z.number().int().optional(), errors: z.array(z.object({path: z.string().optional(), keyword: z.string().optional(), message: z.string().optional()})).optional(), truncated: z.boolean().optional(), documentHash: z.string().optional(), schemaHash: z.string().optional(), schemaForm: z.string().optional(), pointer: z.string().optional(), validatedType: z.string().optional()}).optional(), attestation: z.object({keyId: z.string().optional(), alg: z.string().optional(), address: z.string().optional(), contentHash: z.string().optional(), nonce: z.string().optional(), signedAt: z.string().optional(), signature: z.string().optional(), verify: z.object({message: z.string().optional(), howTo: z.string().optional()}).optional()}).optional(), error: z.string().optional()}).and(z.record(z.string(), z.unknown()));

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
};

/**
 * Cited Validate — JSON API response vs JSON Schema, signed pass/fail + per-field errors (keyless x402)
 * 
 * GET /buy/validate
 */
export const getApiBuyValidate = async (args: GetApiBuyValidateArgs, options?: GetApiBuyValidateOptions) => {
const {baseUrl = "https://network.mercury-hq.com", fetch: fetchFn = fetch} = options ?? {}

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

if (args.url != null) query.append("url", String(args.url))
if (args.schema != null) query.append("schema", String(args.schema))
if (args.pointer != null) query.append("pointer", String(args.pointer))

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

const res = await fetchFn(url, {method: "GET", headers})

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

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