/**
 * Browser half of the model probe: the settings card's connectivity check.
 * Posts the card's unsaved connection drafts to the host /describe-image/models
 * route; the host resolves the key through the credential seam (the key never
 * crosses into the browser), lists the endpoint's models, and returns only the
 * id list — a success doubles as the connectivity and credential check.
 * @module @linxin666/dsh-tool-describe-image/client/model-probe
 */

/** The host model-probe endpoint, same-origin with the web shell. */
export const MODELS_ENDPOINT = '/describe-image/models'

/** The host model-test endpoint: one minimal completion ping of the selected model. */
export const MODEL_TEST_ENDPOINT = '/describe-image/models/test'

/** The connection drafts one probe sends; empty strings fall back to the stored settings. */
export interface ModelProbeDraft {
  baseURL: string
  apiStyle: string
  apiKey: string
}

/**
 * Ask the host to list the configured endpoint's models. The drafts ride the
 * body so an unsaved endpoint can be verified before saving; the host owns
 * validation, key resolution, and the upstream call.
 * @param draft - the card's current connection drafts.
 * @returns the served model ids, or a structured rejection.
 */
export async function fetchEndpointModels(
  draft: ModelProbeDraft,
): Promise<{ ok: true; models: string[] } | { ok: false; message: string }> {
  let response: Response
  try {
    response = await fetch(MODELS_ENDPOINT, {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(draft),
    })
  } catch {
    return { ok: false, message: 'network-failed' }
  }
  let envelope: unknown
  try {
    envelope = await response.json()
  } catch {
    return { ok: false, message: 'bad-response' }
  }
  const record = envelope as { ok?: unknown; value?: unknown; error?: unknown } | null
  if (typeof record !== 'object' || record === null) return { ok: false, message: 'bad-response' }
  if (record.ok === true && typeof record.value === 'object' && record.value !== null) {
    const value = record.value as { models?: unknown }
    if (Array.isArray(value.models) && value.models.every(id => typeof id === 'string')) {
      return { ok: true, models: value.models as string[] }
    }
    return { ok: false, message: 'bad-response' }
  }
  const message = (record.error as { message?: unknown } | null)?.message
  return { ok: false, message: typeof message === 'string' && message !== '' ? message : 'server-failed' }
}

/**
 * Ping the selected model through the host test route: one minimal
 * completion call (`max_tokens` 1) whose round-trip latency is the model's
 * own first-response time — not the models listing's. The host owns key
 * resolution and the upstream call; the browser receives only the latency.
 * @param draft - the card's connection drafts plus the selected model id.
 * @returns the round-trip milliseconds, or a structured rejection.
 */
export async function testEndpointModel(
  draft: ModelProbeDraft & { model: string },
): Promise<{ ok: true; latencyMs: number } | { ok: false; message: string }> {
  let response: Response
  try {
    response = await fetch(MODEL_TEST_ENDPOINT, {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(draft),
    })
  } catch {
    return { ok: false, message: 'network-failed' }
  }
  let envelope: unknown
  try {
    envelope = await response.json()
  } catch {
    return { ok: false, message: 'bad-response' }
  }
  const record = envelope as { ok?: unknown; value?: unknown; error?: unknown } | null
  if (typeof record !== 'object' || record === null) return { ok: false, message: 'bad-response' }
  if (record.ok === true && typeof record.value === 'object' && record.value !== null) {
    const value = record.value as { latencyMs?: unknown }
    if (typeof value.latencyMs === 'number' && Number.isFinite(value.latencyMs) && value.latencyMs >= 0) {
      return { ok: true, latencyMs: value.latencyMs }
    }
    return { ok: false, message: 'bad-response' }
  }
  const message = (record.error as { message?: unknown } | null)?.message
  return { ok: false, message: typeof message === 'string' && message !== '' ? message : 'server-failed' }
}