class ApiService {
  constructor() {
    this.baseUrl = '/api';
    this.token = localStorage.getItem('dashy_token');
    this.subscribers = new Set();
    this.connectSSE();
  }

  connectSSE() {
    const url = `${this.baseUrl}/stream`;
    this.sse = new EventSource(url);

    this.sse.onmessage = (event) => {
      try {
        const data = JSON.parse(event.data);
        if (data.type === 'refresh') {
          this.notify();
        }
      } catch (e) {
        // Fallback for non-JSON messages or just generic refresh
        this.notify();
      }
    };

    this.sse.onerror = (err) => {
      console.error('SSE connection error. EventSource will auto-reconnect.', err);
    };
  }

  subscribe(fn) {
    this.subscribers.add(fn);
    return () => this.subscribers.delete(fn);
  }

  notify() {
    for (const fn of this.subscribers) fn();
  }

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

    const response = await fetch(`${this.baseUrl}${endpoint}`, {
      ...options,
      headers,
    });

    if (!response.ok) {
      if (response.status === 401) {
        this.logout();
      }
      let errorMsg = response.statusText;
      try {
        const data = await response.json();
        if (data && data.detail) errorMsg = data.detail;
      } catch (e) {}
      throw new Error(`API Error: ${errorMsg}`);
    }

    return response.json();
  }

  async login(id, password) {
    const response = await fetch(`${this.baseUrl}/token`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ id, password }),
    });

    if (!response.ok) {
      throw new Error('Login failed');
    }

    const data = await response.json();
    this.token = data.access_token;
    localStorage.setItem('dashy_token', this.token);
    this.notify();
    return data;
  }

  logout() {
    this.token = null;
    localStorage.removeItem('dashy_token');
    this.notify();
  }

  async getUsers() {
    return this.request('/users');
  }

  async getWorkspace() {
    return this.request('/workspace');
  }

  async updateWorkspace(updates) {
    const data = await this.request('/workspace', {
      method: 'PATCH',
      body: JSON.stringify(updates),
    });
    this.notify();
    return data;
  }

  async createUser(userData) {
    const data = await this.request('/users', {
      method: 'POST',
      body: JSON.stringify(userData),
    });
    this.notify();
    return data;
  }

  async updateUser(id, updates) {
    const data = await this.request(`/users/${id}`, {
      method: 'PATCH',
      body: JSON.stringify(updates),
    });
    this.notify();
    return data;
  }

  async deleteUser(id) {
    const data = await this.request(`/users/${id}`, {
      method: 'DELETE',
    });
    this.notify();
    return data;
  }

  async changePassword(id, oldPassword, newPassword) {
    const response = await fetch(`${this.baseUrl}/users/${id}/password`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        ...(this.token ? { Authorization: `Bearer ${this.token}` } : {}),
      },
      body: JSON.stringify({ old_password: oldPassword, new_password: newPassword }),
    });
    if (!response.ok) {
      let detail = response.statusText;
      try { const j = await response.json(); if (j.detail) detail = j.detail; } catch {}
      throw new Error(detail);
    }
    return response.json();
  }

  async getTasks() {
    return this.request('/tasks');
  }

  async getDeletedTasks() {
    return this.request('/tasks/deleted');
  }

  async getAudit() {
    return this.request('/audit');
  }

  async createTask(taskData) {
    const data = await this.request('/tasks', {
      method: 'POST',
      body: JSON.stringify(taskData),
    });
    this.notify();
    return data;
  }

  async updateTask(id, updates) {
    const data = await this.request(`/tasks/${id}`, {
      method: 'PATCH',
      body: JSON.stringify(updates),
    });
    this.notify();
    return data;
  }

  async restoreTask(id) {
    const data = await this.request(`/tasks/${id}/restore`, {
      method: 'POST',
    });
    this.notify();
    return data;
  }

  async deleteTask(id) {
    const data = await this.request(`/tasks/${id}`, {
      method: 'DELETE',
    });
    this.notify();
    return data;
  }

  async getTaskNotes(taskId) {
    return this.request(`/tasks/${taskId}/notes`);
  }

  async createTaskNote(taskId, body) {
    const data = await this.request(`/tasks/${taskId}/notes`, {
      method: 'POST',
      body: JSON.stringify({ body }),
    });
    this.notify();
    return data;
  }

  async getSchedule(startDate, endDate) {
    return this.request(`/calendar/schedule?start_date=${startDate}&end_date=${endDate}`);
  }

  async triggerSync() {
    const data = await this.request('/calendar/sync', { method: 'POST' });
    this.notify();
    return data;
  }

  async addAudit(auditData) {
    const data = await this.request('/audit', {
      method: 'POST',
      body: JSON.stringify(auditData),
    });
    this.notify();
    return data;
  }
}

window.api = new ApiService();