import { APP_ID, WORKFLOW } from './config'

const TOKEN_KEY = 'zk_lead_desk_token'
const USER_KEY = 'zk_lead_desk_user'

/**
 * HTTP client for the Zino gateway.
 *
 * Most routes are app-scoped (`/app/536/...`); login is not. The JWT persists
 * in localStorage so a refresh does not bounce the operator back to the login
 * screen mid-review.
 */
export class ZinoClient {
  constructor(baseUrl, onAuthError) {
    this.baseUrl = String(baseUrl).replace(/\/+$/, '')
    this.token = null
    this.onAuthError = onAuthError
    if (typeof window !== 'undefined') this.token = localStorage.getItem(TOKEN_KEY)
  }

  setAuthErrorHandler(fn) { this.onAuthError = fn }

  setToken(token) {
    this.token = token
    if (typeof window === 'undefined') return
    if (token) localStorage.setItem(TOKEN_KEY, token)
    else localStorage.removeItem(TOKEN_KEY)
  }

  getToken() { return this.token }

  setStoredUser(user) {
    if (typeof window === 'undefined') return
    if (user) localStorage.setItem(USER_KEY, JSON.stringify(user))
    else localStorage.removeItem(USER_KEY)
  }

  getStoredUser() {
    if (typeof window === 'undefined') return null
    try { return JSON.parse(localStorage.getItem(USER_KEY) || 'null') } catch { return null }
  }

  async request(method, path, body) {
    const headers = { 'Content-Type': 'application/json' }
    if (this.token) headers['Authorization'] = `Bearer ${this.token}`

    const res = await fetch(`${this.baseUrl}${path}`, {
      method,
      headers,
      body: body !== undefined ? JSON.stringify(body) : undefined,
    })

    if (res.status === 401) {
      this.setToken(null)
      this.setStoredUser(null)
      this.onAuthError?.()
      throw { status: 401, message: 'Session expired — sign in again' }
    }
    if (!res.ok) {
      let message = res.statusText
      try {
        const j = await res.json()
        message = j.error || j.message || message
      } catch { /* non-JSON body */ }
      throw { status: res.status, message }
    }
    if (res.status === 204) return undefined
    return res.json()
  }

  /* ── The support desk ────────────────────────────────────────────────────
     Not app-scoped: these are the platform's own agent routes, and the token
     this console already holds is accepted on them as-is. A conversation is a
     session; a question is a message on it. */

  /** This operator's conversations with the desk, newest first. */
  deskSessions(agentId) {
    return this.request('GET', `/api/agent-sessions?agent_id=${agentId}`)
  }

  /** Open a new conversation. */
  deskStartSession(agentId) {
    return this.request('POST', '/api/agent-sessions', { agent_id: agentId })
  }

  /** The transcript of one conversation. */
  deskMessages(sessionId) {
    return this.request('GET', `/api/agent-sessions/${sessionId}/messages`)
  }

  /**
   * Ask. Answers with the rows the backend persisted for the turn —
   * { user_message, call_api_message, agent_message } — not a bare string.
   *
   * These take twenty to forty seconds: the desk runs real queries against the
   * book before it answers. The caller has to say so, or the panel looks hung.
   */
  deskAsk(sessionId, content) {
    return this.request('POST', `/api/agent-sessions/${sessionId}/messages`, { content })
  }

  /**
   * org_id must be a STRING. The gateway rejects a number with
   * "cannot unmarshal number into Go struct field LoginRequest.org_id".
   */
  async login(email, password, orgId) {
    const res = await this.request('POST', '/usr/login', {
      email,
      password,
      org_id: String(orgId),
    })
    if (res?.token) {
      this.setToken(res.token)
      this.setStoredUser(res.user || null)
    }
    return res
  }

  logout() {
    this.setToken(null)
    this.setStoredUser(null)
  }

  /**
   * Paginated records for a record view, filtered server-side.
   *
   * The POST body is NOT the same shape as the GET query params: the view is
   * named by `rv_template_uid` (not `rv_id`, which is the GET spelling), and
   * paging/sort/filters all live INSIDE `search_query`. Sending them at the top
   * level returns `400 Missing param: rv_template_uid (body)`.
   */
  recordView(rvUid, params = {}) {
    return this.request('POST', `/app/${APP_ID}/view/recordview`, {
      rv_template_uid: rvUid,
      search_query: {
        page: params.page ?? 1,
        limit: params.limit ?? 50,
        sort_by: params.sort_by ?? '',
        sort_dir: params.sort_dir ?? 'desc',
        search: params.search ?? '',
        filters: (params.filters ?? []).map((f) => ({
          field_key: f.field_key,
          value: f.value,
          value2: '',
          data_type: f.data_type ?? 'string',
        })),
      },
    })
  }

  /**
   * Rows only. The response key differs by source type — workflow views return
   * `data`, rdbms views have been seen returning `records`.
   */
  async rows(rvUid, params = {}) {
    const r = await this.recordView(rvUid, params)
    return r?.data ?? r?.records ?? r?.rows ?? []
  }

  detailView(dvUid, instanceId) {
    return this.request(
      'GET',
      `/app/${APP_ID}/view/detailview/${dvUid}?instance_id=${encodeURIComponent(String(instanceId))}`,
    )
  }

  /**
   * The LIVE definition of an activity's form: fields, types, select options,
   * which are mandatory. Read rather than hardcoded so that adding a field in
   * Studio and redeploying surfaces it here with no frontend change — the
   * workflow stays the source of truth.
   */
  formSchema(activityUid, instanceId) {
    return this.request('POST', `/app/${APP_ID}/view/form-screens`, {
      activity_id: activityUid,
      device_type: 'desktop',
      ...(instanceId ? { instance_id: instanceId } : {}),
    })
  }

  /** Start a new instance via one of the three INIT activities. */
  start(activityUid, data) {
    return this.request('POST', `/app/${APP_ID}/start`, {
      workflow_uuid: WORKFLOW,
      activity_id: activityUid,
      data,
    })
  }

  /**
   * Perform an activity on an existing instance. The workflow refuses what the
   * signed-in user may not do — a permission denial arrives as 403 here and as
   * 400 on /start, both carrying "permission denied".
   */
  activity(instanceId, activityUid, data) {
    return this.request('POST', `/app/${APP_ID}/activity`, {
      workflow_uuid: WORKFLOW,
      instance_id: instanceId,
      activity_id: activityUid,
      data,
    })
  }

  /**
   * Upload a file and get back a reference — {uuid, blob_path, original_name,
   * mime_type}. The field context matters: the backend resolves the field's
   * own config (allowed types, size limit, ocr_config) server-side from it and
   * ignores anything the client claims.
   */
  async uploadFile(file, ctx) {
    const form = new FormData()
    form.append('file', file)
    // workflow_uuid is REQUIRED and is fixed for this app, so it is taken from
    // config rather than from ctx. Passing it optionally is how the first
    // version shipped: the upload sent activity_id, field_id and instance_id
    // and got back `Missing required params: workflow_uuid`.
    form.append('workflow_uuid', WORKFLOW)
    if (ctx.activityId) form.append('activity_id', ctx.activityId)
    if (ctx.fieldId)    form.append('field_id', ctx.fieldId)
    if (ctx.instanceId) form.append('instance_id', String(ctx.instanceId))
    const headers = {}
    if (this.token) headers['Authorization'] = `Bearer ${this.token}`
    const res = await fetch(`${this.baseUrl}/app/${APP_ID}/upload`, { method: 'POST', headers, body: form })
    if (!res.ok) {
      let message = res.statusText
      try { const j = await res.json(); message = j.error || j.message || message } catch { /* non-JSON */ }
      throw { status: res.status, message }
    }
    return res.json()
  }

  /**
   * Extract from an ALREADY-UPLOADED file. Sends a reference, not the bytes —
   * the document crosses the wire once, survives a reload, and re-extracting
   * costs no re-upload. The ocr_config (which fields to pull, where they map)
   * is resolved server-side from the deployed workflow; anything the client
   * sends is ignored.
   */
  ocrExtract(fileRef, ctx) {
    return this.request('POST', `/app/${APP_ID}/ocr-extract`, {
      workflow_uuid: WORKFLOW,
      activity_id: ctx.activityId,
      field_id: ctx.fieldId,
      instance_id: ctx.instanceId || undefined,
      files: [fileRef],
    })
  }

  instance(instanceId) {
    return this.request('POST', `/app/${APP_ID}/instance`, {
      workflow_uuid: WORKFLOW,
      instance_id: instanceId,
    })
  }

  /**
   * The instance's audit trail: one entry per activity performed, with WHO
   * performed it and the data they wrote.
   *
   * Must be the APP-SCOPED path. The bare `/view/audit` is not an API route at
   * all — it falls through to the SPA and returns HTML with a 200, which
   * parses as a JSON error rather than an HTTP one.
   */
  audit(instanceId) {
    return this.request('GET', `/app/${APP_ID}/view/audit?instance_id=${encodeURIComponent(String(instanceId))}`)
  }
}