// ── Token storage ──────────────────────────────────────────────────────────────
const TOKEN_KEY = 'julia_token'
export const getToken = (): string | null => localStorage.getItem(TOKEN_KEY)
export const setToken = (t: string): void => { localStorage.setItem(TOKEN_KEY, t) }
export const clearToken = (): void => { localStorage.removeItem(TOKEN_KEY) }

// ── Base fetch with auth ───────────────────────────────────────────────────────
async function request<T>(url: string, init: RequestInit = {}): Promise<T> {
  const token = getToken()
  const headers: Record<string, string> = {
    ...(init.headers as Record<string, string> ?? {}),
  }
  if (token) headers['Authorization'] = `Bearer ${token}`
  const r = await fetch(url, { ...init, headers })
  if (r.status === 401) {
    clearToken()
    window.location.reload()
    throw new Error('Unauthorized')
  }
  if (!r.ok) {
    const text = await r.text()
    throw new Error(text || `HTTP ${r.status}`)
  }
  return r.json() as Promise<T>
}

// ── Auth ───────────────────────────────────────────────────────────────────────
export function login(email: string, password: string): Promise<{ token: string; email: string }> {
  return request('/auth/login', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, password }),
  })
}

export function getMe(): Promise<{ email: string }> {
  return request('/auth/me')
}

// ── Conversations ─────────────────────────────────────────────────────────────
export interface Conversation {
  id: string
  title: string
  created_at: string
  updated_at: string
}

export interface ConversationDetail extends Conversation {
  messages: Array<{ role: string; text: string; meta?: unknown }>
}

export function listConversations(): Promise<Conversation[]> {
  return request('/conversations')
}

export function getConversation(id: string): Promise<ConversationDetail> {
  return request(`/conversations/${id}`)
}

export function createConversation(title: string, messages: unknown[]): Promise<Conversation> {
  return request('/conversations', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ title, messages }),
  })
}

export function updateConversation(id: string, title: string, messages: unknown[]): Promise<Conversation> {
  return request(`/conversations/${id}`, {
    method: 'PUT',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ title, messages }),
  })
}

export function deleteConversation(id: string): Promise<{ status: string }> {
  return request(`/conversations/${id}`, { method: 'DELETE' })
}

// ── Ingestion ─────────────────────────────────────────────────────────────────
export interface UploadResponse { job_id: string; doc_id: string; status: string }

export interface JobStatus {
  job_id: string; doc_id: string; filename: string
  status: 'queued' | 'processing' | 'done' | 'failed'
  chunks_stored: number; error: string | null
  created_at: string; updated_at: string
}

export interface Document { doc_id: string; filename: string }

export function uploadDocument(file: File, category: string): Promise<UploadResponse> {
  const form = new FormData()
  form.append('file', file)
  form.append('category', category)
  return request('/ingest/upload', { method: 'POST', body: form })
}

export function getJobStatus(jobId: string): Promise<JobStatus> {
  return request(`/ingest/status/${jobId}`)
}

export function listDocuments(): Promise<{ total: number; documents: Document[] }> {
  return request('/ingest/documents')
}

export function deleteDocument(docId: string): Promise<{ status: string; doc_id: string }> {
  return request(`/ingest/documents/${docId}`, { method: 'DELETE' })
}

export function clearDocuments(): Promise<{ status: string }> {
  return request('/ingest/documents', { method: 'DELETE' })
}

// ── Query ─────────────────────────────────────────────────────────────────────
export interface Citation { filename: string; page: number | string; snippet?: string }

export interface AskResponse {
  answer: string
  citations: Citation[]
  source_map: Citation[]
  chunks_used: number
  path: 'vector' | 'sql'
  sql: string | null
}

export interface HistoryMessage { role: 'user' | 'assistant'; content: string }

export async function askQuestionStream(
  question: string,
  history: HistoryMessage[],
  topK = 6,
  category = '',
  onToken: (token: string) => void,
  onDone: (meta: AskResponse) => void,
  onError: (msg: string) => void,
  onStatus?: (status: string) => void,
  uiLanguage = '',
): Promise<void> {
  const token = getToken()
  const res = await fetch('/query/ask/stream', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      ...(token ? { Authorization: `Bearer ${token}` } : {}),
    },
    body: JSON.stringify({ question, history, top_k: topK, category, ui_language: uiLanguage }),
  })
  if (!res.ok || !res.body) { onError(`HTTP ${res.status}`); return }
  const reader = res.body.getReader()
  const dec = new TextDecoder()
  let buf = ''
  while (true) {
    const { done, value } = await reader.read()
    if (done) break
    buf += dec.decode(value, { stream: true })
    const lines = buf.split('\n')
    buf = lines.pop() ?? ''
    for (const line of lines) {
      if (!line.startsWith('data: ')) continue
      const event = JSON.parse(line.slice(6))
      if (event.type === 'token') onToken(event.content)
      else if (event.type === 'status') onStatus?.(event.status)
      else if (event.type === 'done') onDone({
        answer: event.answer ?? '',
        citations: event.citations ?? [],
        source_map: event.source_map ?? [],
        chunks_used: event.chunks_used ?? 0,
        path: event.path,
        sql: event.sql ?? null,
      })
      else if (event.type === 'error') onError(event.message)
    }
  }
}