import axios from 'axios';
import { getAuthHeaders } from '../utils/auth';

const API_BASE_URL = process.env.REACT_APP_API_URL || 'http://localhost:8080';

export interface Policy {
  name: string;
  policy: string;
  type?: 'built-in' | 'custom';
  createdAt?: string;
}

export interface CreatePolicyRequest {
  name: string;
  policy: string;
}

export interface AttachPolicyRequest {
  policyName: string;
  userName: string;
}

export interface PolicyListResponse {
  policies: Policy[];
}

export interface PolicyTemplate {
  name: string;
  description: string;
  generatePolicy: (bucketName: string) => object;
}

export const policyTemplates: Record<string, PolicyTemplate> = {
  bucketFullAccess: {
    name: 'Bucket Full Access',
    description: 'Grants full access to a specific bucket',
    generatePolicy: (bucketName: string) => ({
      Version: '2012-10-17',
      Statement: [
        {
          Effect: 'Allow',
          Action: ['s3:*'],
          Resource: [
            `arn:aws:s3:::${bucketName}`,
            `arn:aws:s3:::${bucketName}/*`
          ],
        },
      ],
    }),
  },
  bucketReadOnly: {
    name: 'Bucket Read Only',
    description: 'Grants read-only access to a specific bucket',
    generatePolicy: (bucketName: string) => ({
      Version: '2012-10-17',
      Statement: [
        {
          Effect: 'Allow',
          Action: [
            's3:GetObject',
            's3:ListBucket',
            's3:GetBucketLocation',
          ],
          Resource: [
            `arn:aws:s3:::${bucketName}`,
            `arn:aws:s3:::${bucketName}/*`
          ],
        },
      ],
    }),
  },
  bucketWriteOnly: {
    name: 'Bucket Write Only',
    description: 'Grants write-only access to a specific bucket',
    generatePolicy: (bucketName: string) => ({
      Version: '2012-10-17',
      Statement: [
        {
          Effect: 'Allow',
          Action: [
            's3:PutObject',
            's3:DeleteObject',
            's3:ListBucket',
          ],
          Resource: [
            `arn:aws:s3:::${bucketName}`,
            `arn:aws:s3:::${bucketName}/*`
          ],
        },
      ],
    }),
  },
};

class PolicyService {
  private baseURL = `${API_BASE_URL}/api`;

  async listPolicies(): Promise<Policy[]> {
    try {
      const response = await axios.get<PolicyListResponse>(`${this.baseURL}/policies`, {
        headers: getAuthHeaders(),
      });
      return response.data.policies || [];
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(error.response?.data?.error || 'Failed to fetch policies');
      }
      throw error;
    }
  }

  async createPolicy(policyData: CreatePolicyRequest): Promise<void> {
    try {
      await axios.post(`${this.baseURL}/policies`, policyData, {
        headers: getAuthHeaders(),
      });
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(error.response?.data?.error || 'Failed to create policy');
      }
      throw error;
    }
  }

  async deletePolicy(policyName: string): Promise<void> {
    try {
      await axios.delete(`${this.baseURL}/policies/${policyName}`, {
        headers: getAuthHeaders(),
      });
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(error.response?.data?.error || 'Failed to delete policy');
      }
      throw error;
    }
  }

  async getPolicy(policyName: string): Promise<Policy> {
    try {
      const response = await axios.get<Policy>(`${this.baseURL}/policies/${policyName}`, {
        headers: getAuthHeaders(),
      });
      return response.data;
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(error.response?.data?.error || 'Failed to fetch policy');
      }
      throw error;
    }
  }

  async attachPolicy(data: AttachPolicyRequest): Promise<void> {
    try {
      await axios.post(`${this.baseURL}/policies/attach`, data, {
        headers: getAuthHeaders(),
      });
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(error.response?.data?.error || 'Failed to attach policy');
      }
      throw error;
    }
  }

  async detachPolicy(policyName: string, userName: string): Promise<void> {
    try {
      await axios.post(`${this.baseURL}/policies/detach`, 
        { policyName, userName }, 
        {
          headers: getAuthHeaders(),
        }
      );
    } catch (error) {
      if (axios.isAxiosError(error)) {
        throw new Error(error.response?.data?.error || 'Failed to detach policy');
      }
      throw error;
    }
  }

  // Policy validation helper
  validatePolicyJSON(policyString: string): { valid: boolean; error?: string } {
    try {
      const policy = JSON.parse(policyString);
      
      // Basic validation
      if (!policy.Version) {
        return { valid: false, error: 'Policy must have a Version field' };
      }
      if (!policy.Statement || !Array.isArray(policy.Statement)) {
        return { valid: false, error: 'Policy must have a Statement array' };
      }
      if (policy.Statement.length === 0) {
        return { valid: false, error: 'Policy must have at least one statement' };
      }

      // Validate each statement
      for (let i = 0; i < policy.Statement.length; i++) {
        const stmt = policy.Statement[i];
        if (!stmt.Effect || !['Allow', 'Deny'].includes(stmt.Effect)) {
          return { valid: false, error: `Statement ${i + 1}: Effect must be 'Allow' or 'Deny'` };
        }
        if (!stmt.Action) {
          return { valid: false, error: `Statement ${i + 1}: Action is required` };
        }
        if (!stmt.Resource) {
          return { valid: false, error: `Statement ${i + 1}: Resource is required` };
        }
      }

      return { valid: true };
    } catch (e) {
      return { valid: false, error: 'Invalid JSON format' };
    }
  }

  // Generate policy from template
  generatePolicyFromTemplate(templateKey: string, bucketName: string): string {
    const template = policyTemplates[templateKey];
    if (!template) {
      throw new Error('Invalid template');
    }
    const policy = template.generatePolicy(bucketName);
    return JSON.stringify(policy, null, 2);
  }
}

const policyService = new PolicyService();
export default policyService;