import { NextResponse } from 'next/server';
import { getSession } from '@/lib/auth';
import { createMCPClient } from '@/lib/control-center/mcp-client';

export interface Recommendation {
  id: string;
  type: 'follow_up' | 'stale_lead' | 'pipeline_stuck' | 'campaign_response' | 'no_response';
  priority: 'high' | 'medium' | 'low';
  title: string;
  description: string;
  actionLabel: string;
  actionUrl: string;
  contactId?: string;
  contactName?: string;
  daysOverdue?: number;
  pipelineStage?: string;
}

interface RecommendationsResponse {
  recommendations: Recommendation[];
  generatedAt: string;
}

// Fallback recommendations shown when MCP isn't available or returns no data
function getFallbackRecommendations(): Recommendation[] {
  return [
    {
      id: 'fallback-import-contacts',
      type: 'follow_up',
      priority: 'high',
      title: 'Import your contacts',
      description: 'Get started by importing your existing contacts from a CSV or CRM',
      actionLabel: 'Import Now',
      actionUrl: '/contacts',
    },
    {
      id: 'fallback-configure-sms',
      type: 'follow_up',
      priority: 'medium',
      title: 'Set up SMS messaging',
      description: 'Configure two-way SMS to reach contacts via text',
      actionLabel: 'Configure',
      actionUrl: '/settings/sms',
    },
    {
      id: 'fallback-create-pipeline',
      type: 'pipeline_stuck',
      priority: 'medium',
      title: 'Create your first pipeline',
      description: 'Track deals from lead to close with custom stages',
      actionLabel: 'Create Pipeline',
      actionUrl: '/opportunities',
    },
    {
      id: 'fallback-explore-control-center',
      type: 'campaign_response',
      priority: 'low',
      title: 'Explore AI Control Center',
      description: 'Use AI to analyze your CRM data and get insights',
      actionLabel: 'Explore',
      actionUrl: '/control-center',
    },
  ];
}

export async function GET() {
  const session = await getSession();
  if (!session) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  try {
    const mcpClient = await createMCPClient();

    if (!mcpClient) {
      // Return fallback recommendations if MCP not configured
      return NextResponse.json({
        recommendations: getFallbackRecommendations(),
        generatedAt: new Date().toISOString(),
      });
    }

    const isHealthy = await mcpClient.healthCheck();
    if (!isHealthy) {
      return NextResponse.json({
        recommendations: getFallbackRecommendations(),
        generatedAt: new Date().toISOString(),
      });
    }

    // Ensure connected for tool execution
    await mcpClient.connect();

    const recommendations: Recommendation[] = [];

    // 1. Get conversations and check for ones needing follow-up
    try {
      const conversationsResult = await mcpClient.executeTool('search_conversations', {
        limit: 50,
      });

      if (conversationsResult.success && conversationsResult.result) {
        const data = conversationsResult.result as any;
        const conversations = data?.conversations || data || [];

        for (const conv of (Array.isArray(conversations) ? conversations : []).slice(0, 15)) {
          // Check if last message was from us and no response
          const lastMessageAt = conv.lastMessageDate || conv.dateUpdated || conv.updatedAt;
          const lastDate = lastMessageAt ? new Date(lastMessageAt) : null;
          const daysSinceMessage = lastDate
            ? Math.floor((Date.now() - lastDate.getTime()) / (1000 * 60 * 60 * 24))
            : null;

          const lastMessageDirection = conv.lastMessageDirection || conv.lastMessageType || '';
          const isOutbound = lastMessageDirection === 'outbound' || lastMessageDirection === 'out';

          if (daysSinceMessage && daysSinceMessage >= 7 && isOutbound) {
            const contactName = conv.contactName || conv.fullName || conv.name || 'contact';
            recommendations.push({
              id: `no-response-${conv.id}`,
              type: 'no_response',
              priority: daysSinceMessage >= 14 ? 'high' : 'medium',
              title: `Follow up with ${contactName}`,
              description: `No response in ${daysSinceMessage} days since your last message`,
              actionLabel: 'Send Follow-up',
              actionUrl: `/conversations/${conv.id}`,
              contactId: conv.contactId,
              contactName: contactName,
              daysOverdue: daysSinceMessage,
            });
          }
        }
      }
    } catch (e) {
      console.warn('[Recommendations] Failed to fetch conversations:', e);
    }

    // 2. Get opportunities stuck in pipeline stages
    try {
      const oppsResult = await mcpClient.executeTool('search_opportunities', {
        status: 'open',
        limit: 30,
      });

      if (oppsResult.success && oppsResult.result) {
        const data = oppsResult.result as any;
        const opportunities = data?.opportunities || data || [];

        for (const opp of (Array.isArray(opportunities) ? opportunities : []).slice(0, 20)) {
          const stageEnteredAt = opp.lastStageChangeAt || opp.stageEnteredAt || opp.updatedAt || opp.dateUpdated;
          const stageDate = stageEnteredAt ? new Date(stageEnteredAt) : null;
          const daysInStage = stageDate
            ? Math.floor((Date.now() - stageDate.getTime()) / (1000 * 60 * 60 * 24))
            : null;

          // Flag opportunities stuck in same stage for 14+ days
          if (daysInStage && daysInStage >= 14) {
            const oppName = opp.name || opp.title || 'Opportunity';
            const stageName = opp.pipelineStage || opp.stageName || opp.stage || 'current stage';
            recommendations.push({
              id: `pipeline-stuck-${opp.id}`,
              type: 'pipeline_stuck',
              priority: daysInStage >= 30 ? 'high' : 'medium',
              title: `Move "${oppName}" forward`,
              description: `Stuck in "${stageName}" for ${daysInStage} days`,
              actionLabel: 'Review Deal',
              actionUrl: `/opportunities/${opp.id}`,
              contactId: opp.contactId,
              contactName: opp.contactName || opp.contact?.name,
              daysOverdue: daysInStage,
              pipelineStage: stageName,
            });
          }
        }
      }
    } catch (e) {
      console.warn('[Recommendations] Failed to fetch opportunities:', e);
    }

    // 3. Get email campaigns (optional - may not have data)
    try {
      const campaignsResult = await mcpClient.executeTool('get_email_campaigns', {
        limit: 10,
      });

      if (campaignsResult.success && campaignsResult.result) {
        const data = campaignsResult.result as any;
        const campaigns = data?.campaigns || data || [];

        for (const campaign of (Array.isArray(campaigns) ? campaigns : []).slice(0, 5)) {
          // Check for campaigns with good open/click rates that might need follow-up
          const opens = campaign.opens || campaign.openCount || 0;
          const clicks = campaign.clicks || campaign.clickCount || 0;

          if (opens > 0 || clicks > 0) {
            recommendations.push({
              id: `campaign-engagement-${campaign.id}`,
              type: 'campaign_response',
              priority: clicks > 5 ? 'high' : 'medium',
              title: `"${campaign.name || 'Campaign'}" has engagement`,
              description: `${opens} opens, ${clicks} clicks - follow up with engaged leads`,
              actionLabel: 'View Campaign',
              actionUrl: `/campaigns/${campaign.id}`,
            });
          }
        }
      }
    } catch (e) {
      console.warn('[Recommendations] Failed to fetch campaigns:', e);
    }

    // 4. Get contacts and find ones needing outreach
    try {
      const contactsResult = await mcpClient.executeTool('search_contacts', {
        limit: 30,
      });

      if (contactsResult.success && contactsResult.result) {
        const data = contactsResult.result as any;
        const contacts = data?.contacts || data || [];

        for (const contact of (Array.isArray(contacts) ? contacts : []).slice(0, 20)) {
          const dateAdded = contact.dateAdded || contact.createdAt || contact.dateCreated;
          const addedDate = dateAdded ? new Date(dateAdded) : null;
          const daysSinceAdded = addedDate
            ? Math.floor((Date.now() - addedDate.getTime()) / (1000 * 60 * 60 * 24))
            : null;

          // Check if contact was added in last 14 days and has no conversation
          const hasConversation = contact.lastMessageDate || contact.lastConversationDate;

          if (daysSinceAdded !== null && daysSinceAdded <= 14 && !hasConversation) {
            const firstName = contact.firstName || contact.name?.split(' ')[0] || '';
            const lastName = contact.lastName || '';
            const displayName = firstName || contact.email || 'new contact';

            recommendations.push({
              id: `new-contact-${contact.id}`,
              type: 'follow_up',
              priority: daysSinceAdded <= 3 ? 'high' : 'medium',
              title: `Reach out to ${displayName}`,
              description: `Added ${getRelativeTime(dateAdded)} - no outreach yet`,
              actionLabel: 'Start Conversation',
              actionUrl: `/contacts/${contact.id}`,
              contactId: contact.id,
              contactName: firstName ? `${firstName} ${lastName}`.trim() : contact.email,
            });
          }
        }
      }
    } catch (e) {
      console.warn('[Recommendations] Failed to fetch contacts:', e);
    }

    // Sort by priority and limit to top 4
    const priorityOrder = { high: 0, medium: 1, low: 2 };
    recommendations.sort((a, b) => priorityOrder[a.priority] - priorityOrder[b.priority]);
    const topRecommendations = recommendations.slice(0, 4);

    // If no recommendations from MCP data, return fallback recommendations
    const finalRecommendations = topRecommendations.length > 0
      ? topRecommendations
      : getFallbackRecommendations();

    const response: RecommendationsResponse = {
      recommendations: finalRecommendations,
      generatedAt: new Date().toISOString(),
    };

    return NextResponse.json(response);
  } catch (error) {
    console.error('[Recommendations] Error:', error);
    // Return fallback recommendations on error instead of failing
    return NextResponse.json({
      recommendations: getFallbackRecommendations(),
      generatedAt: new Date().toISOString(),
    });
  }
}

function getRelativeTime(dateString: string | number | undefined): string {
  if (!dateString) return 'recently';

  const date = typeof dateString === 'number'
    ? new Date(dateString * 1000)
    : new Date(dateString);

  const now = new Date();
  const diffMs = now.getTime() - date.getTime();
  const diffDays = Math.floor(diffMs / (1000 * 60 * 60 * 24));

  if (diffDays === 0) return 'today';
  if (diffDays === 1) return 'yesterday';
  if (diffDays < 7) return `${diffDays} days ago`;
  if (diffDays < 14) return 'last week';
  return `${Math.floor(diffDays / 7)} weeks ago`;
}