import {z} from 'zod'

export type GetApiBuyDiffArgs = {url: string, prevHash?: string | undefined, prevText?: string | undefined, format?: ('text' | 'markdown') | undefined};

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

export const getApiBuyDiffResponse = z.object({ok: z.boolean(), url: z.string(), status: z.number().int().optional(), changed: z.boolean().optional(), fromHash: z.string().optional(), toHash: z.string().optional(), comparedBy: z.enum(["hash", "text"]).optional(), diff: z.object({added: z.number().int().optional(), removed: z.number().int().optional(), hunks: z.array(z.string()).optional(), truncated: z.boolean().optional()}).optional(), text: z.string().optional(), bytes: z.number().int().optional(), contentType: z.string().optional(), fetchedAt: z.string().optional(), error: z.string().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()});

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
};

/**
 * MERCURY Cited Diff — signed web-change proof (refetch + verifiable fromHash->toHash receipt)
 * 
 * GET /buy/diff
 */
export const getApiBuyDiff = async (args: GetApiBuyDiffArgs, options?: GetApiBuyDiffOptions) => {
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.prevHash != null) query.append("prevHash", String(args.prevHash))
if (args.prevText != null) query.append("prevText", String(args.prevText))
if (args.format != null) query.append("format", String(args.format))

const url = `${baseUrl.replace(/\/+$/, '')}/buy/diff${query.size > 0 ? `?${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(getApiBuyDiffResponse, await res.json())
};