/**
 * api.ts
 *
 * Cliente HTTP tipado para a API Helpdesk.
 * Centraliza toda comunicação com o backend — nenhum componente
 * deve chamar fetch() diretamente.
 */

// ─── Configuração ─────────────────────────────────────────────────────────────

const BASE_URL = import.meta.env['VITE_API_URL'] ?? '/api/v1';
const TOKEN_KEY = 'helpdesk:token';

function getToken(): string | null {
  return localStorage.getItem(TOKEN_KEY);
}


// ─── Tipos (espelham o schema do backend) ─────────────────────────────────────

export type TicketStatus   = 'open' | 'in_progress' | 'waiting' | 'resolved' | 'closed';
export type TicketPriority = 'low' | 'medium' | 'high' | 'critical';

export interface Category {
  id:          number;
  name:        string;
  slug:        string;
  description: string | null;
  createdAt:   string;
  updatedAt:   string;
}

export interface Ticket {
  id:          number;
  title:       string;
  description: string;
  status:      TicketStatus;
  priority:    TicketPriority;
  creatorId:   number;
  assigneeId:  number | null;
  categoryId:  number | null;
  dueAt:       string | null;
  resolvedAt:  string | null;
  createdAt:   string;
  updatedAt:   string;
  creatorName?: string;
  assigneeName?: string | null;
  categoryName?: string | null;
}

export interface Comment {
  id:         number;
  content:    string;
  isInternal: boolean;
  ticketId:   number;
  authorId:   number;
  createdAt:  string;
  updatedAt:  string;
}

export interface PaginatedResponse<T> {
  data: T[];
  meta: {
    page:       number;
    limit:      number;
    total:      number;
    totalPages: number;
  };
}

export interface SystemSettings {
  allowRequesterChat: boolean;
}

// ─── Filtros para listagem ────────────────────────────────────────────────────

export interface ListTicketsParams {
  status?:     TicketStatus;
  priority?:   TicketPriority;
  assigneeId?: number;
  creatorId?:  number;
  categoryId?: number;
  page?:       number;
  limit?:      number;
}

// ─── Erro padronizado da API ──────────────────────────────────────────────────

export class ApiError extends Error {
  constructor(
    public readonly status: number,
    message: string,
  ) {
    super(message);
    this.name = 'ApiError';
  }
}

// ─── Função base de fetch ─────────────────────────────────────────────────────

async function request<T>(
  path: string,
  options?: RequestInit,
): Promise<T> {
  const token = getToken();
  const headers: Record<string, string> = { ...options?.headers as Record<string, string> };

  if (options?.body && !headers['Content-Type']) {
    headers['Content-Type'] = 'application/json';
  }
  if (token && !headers['Authorization']) {
    headers['Authorization'] = `Bearer ${token}`;
  }

  const response = await fetch(`${BASE_URL}${path}`, {
    cache: 'no-store',
    ...options,
    headers,
  });

  if (!response.ok) {
    const body = await response.json().catch(() => ({ message: response.statusText }));
    throw new ApiError(
      response.status,
      (body as { message?: string }).message ?? 'Erro desconhecido',
    );
  }

  if (response.status === 204) return null as T;

  return response.json() as Promise<T>;
}

// ─── Tipos adicionais para Auth ───────────────────────────────────────────────

export interface UserResponse {
  id:        number;
  name:      string;
  email:     string;
  role:      'requester' | 'agent' | 'admin';
  isActive:  boolean;
  createdAt: string;
}

export interface AuthResponse {
  token: string;
  user:  UserResponse;
}

export interface StatsResponse {
  totalOpen:       number;
  totalInProgress: number;
  totalWaiting:    number;
  totalResolved:   number;
  totalClosed:     number;
  totalPending:    number;
}

// ─── Endpoints: Tickets ───────────────────────────────────────────────────────

export const api = {
  settings: {
    get(): Promise<SystemSettings> {
      return request('/settings');
    },
    update(data: { allowRequesterChat: boolean }): Promise<SystemSettings> {
      return request('/settings', { method: 'PATCH', body: JSON.stringify(data) });
    }
  },

  stats: {
    get(): Promise<StatsResponse> {
      return request('/stats');
    },
  },

  auth: {
    login(data: { email: string; password: string }): Promise<AuthResponse> {
      return request('/auth/login', { method: 'POST', body: JSON.stringify(data) });
    },
    register(data: { name: string; email: string; password: string; role?: string }): Promise<AuthResponse> {
      return request('/auth/register', { method: 'POST', body: JSON.stringify(data) });
    },
    me(): Promise<UserResponse> {
      return request('/auth/me');
    },
  },

  categories: {
    list(): Promise<Category[]> {
      return request('/categories');
    },
    get(id: number): Promise<Category> {
      return request(`/categories/${id}`);
    },
    create(data: { name: string; slug?: string; description?: string }): Promise<Category> {
      return request('/categories', { method: 'POST', body: JSON.stringify(data) });
    },
    update(id: number, data: { name?: string; slug?: string; description?: string }): Promise<Category> {
      return request(`/categories/${id}`, { method: 'PATCH', body: JSON.stringify(data) });
    },
    delete(id: number): Promise<void> {
      return request(`/categories/${id}`, { method: 'DELETE' });
    }
  },

  tickets: {
    list(params: ListTicketsParams = {}): Promise<PaginatedResponse<Ticket>> {
      const query = new URLSearchParams();
      Object.entries(params).forEach(([key, value]) => {
        if (value !== undefined) query.set(key, String(value));
      });
      const qs = query.toString();
      return request(`/tickets${qs ? `?${qs}` : ''}`);
    },

    get(id: number): Promise<Ticket> {
      return request(`/tickets/${id}`);
    },

    create(data: {
      title:       string;
      description: string;
      priority?:   TicketPriority;
      categoryId?: number;
      creatorId:   number;
    }): Promise<Ticket> {
      return request('/tickets', {
        method: 'POST',
        body:   JSON.stringify(data),
      });
    },

    updateStatus(ticketId: number, status: TicketStatus, reason?: string): Promise<Ticket> {
      return request(`/tickets/${ticketId}/status`, {
        method: 'PATCH',
        body:   JSON.stringify({ status, reason }),
      });
    },

    assign(ticketId: number, assigneeId: number): Promise<Ticket> {
      return request(`/tickets/${ticketId}/assign`, {
        method: 'PATCH',
        body:   JSON.stringify({ assigneeId }),
      });
    },

    updatePriority(ticketId: number, priority: TicketPriority): Promise<Ticket> {
      return request(`/tickets/${ticketId}/priority`, {
        method: 'PATCH',
        body:   JSON.stringify({ priority }),
      });
    },

    delete(id: number): Promise<void> {
      return request(`/tickets/${id}`, { method: 'DELETE' });
    },
  },

  comments: {
    list(ticketId: number): Promise<Comment[]> {
      return request(`/tickets/${ticketId}/comments`);
    },

    add(ticketId: number, data: {
      content:    string;
      isInternal: boolean;
      authorId:   number;
    }): Promise<Comment> {
      return request(`/tickets/${ticketId}/comments`, {
        method: 'POST',
        body:   JSON.stringify(data),
      });
    },
  },

  users: {
    list(): Promise<UserResponse[]> {
      return request('/users');
    },
    create(data: { name: string; email: string; password: string; role: 'admin' | 'agent' | 'requester' }): Promise<UserResponse> {
      return request('/users', {
        method: 'POST',
        body: JSON.stringify(data),
      });
    },
    update(id: number, data: { name?: string; email?: string; password?: string; role?: 'admin' | 'agent' | 'requester'; isActive?: boolean }): Promise<UserResponse> {
      return request(`/users/${id}`, {
        method: 'PATCH',
        body: JSON.stringify(data),
      });
    },
    delete(id: number): Promise<void> {
      return request(`/users/${id}`, { method: 'DELETE' });
    }
  },
};