import type {
  UploadResponse, BuildGraphResponse, CausalTriple,
  GraphData, ChatResponse, AppSettings,
} from './types'

const BASE = '/api'

async function req<T>(path: string, options?: RequestInit): Promise<T> {
  const res = await fetch(BASE + path, options)
  if (!res.ok) {
    const text = await res.text()
    throw new Error(text || `HTTP ${res.status}`)
  }
  return res.json() as Promise<T>
}

export const api = {
  health: () => req<{ status: string; neo4j: string }>('/health'),

  upload: (file: File): Promise<UploadResponse> => {
    const fd = new FormData()
    fd.append('file', file)
    return req<UploadResponse>('/upload', { method: 'POST', body: fd })
  },

  loadSample: (): Promise<UploadResponse> =>
    req<UploadResponse>('/sample'),

  buildGraph: (documentId: string, settings: Partial<AppSettings>): Promise<BuildGraphResponse> =>
    req<BuildGraphResponse>('/build-graph', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        document_id: documentId,
        confidence_threshold: settings.confidenceThreshold ?? 0.5,
        max_chunks: 50,
      }),
    }),

  getTriples: (documentId: string): Promise<{ triples: CausalTriple[] }> =>
    req<{ triples: CausalTriple[] }>(`/triples?document_id=${documentId}`),

  getGraph: (documentId: string): Promise<GraphData> =>
    req<GraphData>(`/graph?document_id=${documentId}`),

  chat: (documentId: string, message: string, settings: Partial<AppSettings>): Promise<ChatResponse> =>
    req<ChatResponse>('/chat', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        document_id: documentId,
        message,
        max_depth: settings.maxDepth ?? 5,
        top_k_chains: settings.topKChains ?? 5,
        theme: settings.theme || null,
      }),
    }),

  reset: () => req<{ status: string }>('/reset', { method: 'POST' }),
}