/**
 * Google Cloud Monitoring resources for MCP
 */
import { McpServer, ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js';
import { getProjectId } from '../../utils/auth.js';
import { GcpMcpError } from '../../utils/error.js';
import { formatTimeSeriesData, getMonitoringClient, TimeSeriesData } from './types.js';

/**
 * Registers Google Cloud Monitoring resources with the MCP server
 * 
 * @param server The MCP server instance
 */
export function registerMonitoringResources(server: McpServer): void {
  // Register a resource for recent metrics
  server.resource(
    'recent-metrics',
    new ResourceTemplate('gcp-monitoring://{projectId}/recent', { list: undefined }),
    async (uri, { projectId }, context) => {
      try {
        const actualProjectId = projectId || await getProjectId();
        const client = getMonitoringClient();
        
        // Default filter from environment variable or use a common metric
        const defaultFilter = process.env.MONITORING_FILTER || 'metric.type="compute.googleapis.com/instance/cpu/utilization"';
        
        // Create time range for the last hour
        const now = new Date();
        const oneHourAgo = new Date(now.getTime() - 60 * 60 * 1000);
        
        const [timeSeries] = await client.listTimeSeries({
          name: `projects/${actualProjectId}`,
          filter: defaultFilter,
          interval: {
            startTime: {
              seconds: Math.floor(oneHourAgo.getTime() / 1000),
              nanos: 0
            },
            endTime: {
              seconds: Math.floor(now.getTime() / 1000),
              nanos: 0
            }
          }
        });
        
        if (!timeSeries || timeSeries.length === 0) {
          return {
            contents: [{
              uri: uri.href,
              text: `# Recent Metrics for Project: ${actualProjectId}\n\nNo metrics found matching filter: ${defaultFilter}`
            }]
          };
        }
        
        const formattedData = formatTimeSeriesData(timeSeries as unknown as TimeSeriesData[]);
        
        return {
          contents: [{
            uri: uri.href,
            text: `# Recent Metrics for Project: ${actualProjectId}\n\nFilter: ${defaultFilter}\nTime Range: ${oneHourAgo.toISOString()} to ${now.toISOString()}\n\n${formattedData}`
          }]
        };
      } catch (error: any) {
        throw new GcpMcpError(
          `Failed to retrieve recent metrics: ${error.message}`,
          error.code || 'UNKNOWN',
          error.statusCode || 500
        );
      }
    }
  );

  // Register a resource for metrics with a custom filter
  server.resource(
    'filtered-metrics',
    new ResourceTemplate('gcp-monitoring://{projectId}/filter/{filter}', { list: undefined }),
    async (uri, { projectId, filter }, context) => {
      try {
        const actualProjectId = projectId || await getProjectId();
        const client = getMonitoringClient();
        
        if (!filter) {
          throw new GcpMcpError('Metric filter is required', 'INVALID_ARGUMENT', 400);
        }
        
        const decodedFilter = Array.isArray(filter) ? decodeURIComponent(filter[0]) : decodeURIComponent(filter);
        
        // Create time range for the last hour
        const now = new Date();
        const oneHourAgo = new Date(now.getTime() - 60 * 60 * 1000);
        
        const [timeSeries] = await client.listTimeSeries({
          name: `projects/${actualProjectId}`,
          filter: decodedFilter,
          interval: {
            startTime: {
              seconds: Math.floor(oneHourAgo.getTime() / 1000),
              nanos: 0
            },
            endTime: {
              seconds: Math.floor(now.getTime() / 1000),
              nanos: 0
            }
          }
        });
        
        if (!timeSeries || timeSeries.length === 0) {
          return {
            contents: [{
              uri: uri.href,
              text: `# Filtered Metrics for Project: ${actualProjectId}\n\nNo metrics found matching filter: ${decodedFilter}`
            }]
          };
        }
        
        const formattedData = formatTimeSeriesData(timeSeries as unknown as TimeSeriesData[]);
        
        return {
          contents: [{
            uri: uri.href,
            text: `# Filtered Metrics for Project: ${actualProjectId}\n\nFilter: ${decodedFilter}\nTime Range: ${oneHourAgo.toISOString()} to ${now.toISOString()}\n\n${formattedData}`
          }]
        };
      } catch (error: any) {
        throw new GcpMcpError(
          `Failed to retrieve filtered metrics: ${error.message}`,
          error.code || 'UNKNOWN',
          error.statusCode || 500
        );
      }
    }
  );
}