/**
 * MemoryOS — Frontend API Client
 *
 * Typed fetch wrapper for all backend endpoints.
 */

const API_BASE = import.meta.env.VITE_API_URL || '/api/v1';

// ── Types ────────────────────────────────────────────────────────────────

export interface User {
  id: string;
  external_id: string;
  created_at: string;
}

export interface Session {
  id: string;
  user_id: string;
  started_at: string;
  ended_at: string | null;
  metadata: Record<string, unknown>;
}

export interface MemoryItem {
  id: string;
  user_id: string;
  session_id: string | null;
  memory_type: 'episodic' | 'semantic' | 'procedural';
  content: string;
  summary: string | null;
  metadata: Record<string, unknown>;
  importance: number;
  recency_score: number;
  access_count: number;
  created_at: string;
  last_accessed: string | null;
}

export interface ScoredMemory {
  memory: MemoryItem;
  score: number;
  cosine_similarity: number;
}

export interface IngestResponse {
  memory_id: string;
  message: string;
}

export interface ChatResponse {
  assistant_message: string;
  retrieved_memories: {
    id: string;
    type: string;
    content: string;
    score: number;
  }[];
}

export interface ContradictionItem {
  id: string;
  memory_a: string;
  memory_b: string;
  detected_at: string;
  resolved: boolean;
  memory_a_content: string | null;
  memory_b_content: string | null;
}

export interface StatsOverview {
  total_memories: number;
  type_counts: {
    episodic: number;
    semantic: number;
    procedural: number;
  };
  avg_importance: number;
  avg_recency_score: number;
  total_users: number;
  total_sessions: number;
  recent_contradictions: ContradictionItem[];
}

export interface GraphNode {
  id: string;
  memory_type: 'episodic' | 'semantic' | 'procedural';
  content: string;
  importance: number;
  created_at: string;
}

export interface GraphEdge {
  source: string;
  target: string;
  similarity: number;
}

export interface GraphData {
  nodes: GraphNode[];
  edges: GraphEdge[];
}

export interface SessionWithMemories extends Session {
  memories: MemoryItem[];
}

// ── Fetch helper ─────────────────────────────────────────────────────────

async function apiFetch<T>(
  path: string,
  options: RequestInit = {}
): Promise<T> {
  const url = `${API_BASE}${path}`;
  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    ...(options.headers as Record<string, string> || {}),
  };

  const response = await fetch(url, { ...options, headers });

  if (!response.ok) {
    const body = await response.json().catch(() => ({ detail: response.statusText }));
    throw new Error(body.detail || `API error: ${response.status}`);
  }

  return response.json();
}

// ── API functions ────────────────────────────────────────────────────────

export async function createUser(externalId: string): Promise<User> {
  return apiFetch<User>('/users', {
    method: 'POST',
    body: JSON.stringify({ external_id: externalId }),
  });
}

export async function getUser(userId: string): Promise<User> {
  return apiFetch<User>(`/users/${userId}`);
}

export async function getUserContext(
  userId: string,
  query: string,
  topK: number = 10
): Promise<ScoredMemory[]> {
  const params = new URLSearchParams({ query, top_k: String(topK) });
  return apiFetch<ScoredMemory[]>(`/users/${userId}/context?${params}`);
}

export async function createSession(
  userId: string,
  metadata: Record<string, unknown> = {}
): Promise<Session> {
  return apiFetch<Session>('/sessions', {
    method: 'POST',
    body: JSON.stringify({ user_id: userId, metadata }),
  });
}

export async function getSession(sessionId: string): Promise<SessionWithMemories> {
  return apiFetch<SessionWithMemories>(`/sessions/${sessionId}`);
}

export async function endSession(sessionId: string): Promise<Session> {
  return apiFetch<Session>(`/sessions/${sessionId}`, { method: 'DELETE' });
}

export async function sendChatMessage(
  sessionId: string,
  userMessage: string
): Promise<ChatResponse> {
  return apiFetch<ChatResponse>(`/sessions/${sessionId}/chat`, {
    method: 'POST',
    body: JSON.stringify({ user_message: userMessage }),
  });
}

export async function ingestMemory(
  userId: string,
  sessionId: string,
  userMessage: string,
  assistantMessage: string
): Promise<IngestResponse> {
  return apiFetch<IngestResponse>('/memories/ingest', {
    method: 'POST',
    body: JSON.stringify({
      user_id: userId,
      session_id: sessionId,
      user_message: userMessage,
      assistant_message: assistantMessage,
    }),
  });
}

export async function searchMemories(
  userId: string,
  query: string,
  memoryType?: string,
  topK: number = 10
): Promise<ScoredMemory[]> {
  const params = new URLSearchParams({
    user_id: userId,
    query,
    top_k: String(topK),
  });
  if (memoryType) params.append('memory_type', memoryType);
  return apiFetch<ScoredMemory[]>(`/memories/search?${params}`);
}

export async function getMemory(memoryId: string): Promise<MemoryItem> {
  return apiFetch<MemoryItem>(`/memories/${memoryId}`);
}

export async function deleteMemory(memoryId: string): Promise<MemoryItem> {
  return apiFetch<MemoryItem>(`/memories/${memoryId}`, { method: 'DELETE' });
}

export async function getContradictions(memoryId: string): Promise<ContradictionItem[]> {
  return apiFetch<ContradictionItem[]>(`/memories/${memoryId}/contradictions`);
}

export async function getStatsOverview(): Promise<StatsOverview> {
  return apiFetch<StatsOverview>('/stats/overview');
}

export async function getGraphData(userId?: string): Promise<GraphData> {
  const params = userId ? `?user_id=${userId}` : '';
  return apiFetch<GraphData>(`/stats/graph${params}`);
}