import { NextRequest, NextResponse } from 'next/server';
import admin from '@/lib/firebase/admin';
import { getApiUrl } from '@/lib/utils/api-url';

/**
 * Timeline View Data
 * Structures MVP checklist pages with their development sessions on a timeline
 */
export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ projectId: string }> }
) {
  try {
    const { projectId } = await params;

    // Load project data, MVP checklist, git history, and activity in parallel
    const db = admin.firestore();
    const projectRef = db.collection('projects').doc(projectId);
    
    const [projectDoc, checklistResponse, gitResponse, activityResponse] = await Promise.all([
      projectRef.get(),
      fetch(getApiUrl(`/api/projects/${projectId}/mvp-checklist`, request)),
      fetch(getApiUrl(`/api/projects/${projectId}/git-history`, request)),
      fetch(getApiUrl(`/api/projects/${projectId}/activity`, request))
    ]);

    const projectData = projectDoc.exists ? projectDoc.data() : null;
    const checklist = await checklistResponse.json();
    const git = await gitResponse.json();
    const activity = await activityResponse.json();

    // Check if checklist exists and has the expected structure
    if (!checklist || checklist.error || !checklist.mvpChecklist || !Array.isArray(checklist.mvpChecklist)) {
      return NextResponse.json({
        workItems: [],
        timeline: {
          start: new Date().toISOString(),
          end: new Date().toISOString(),
          totalDays: 0
        },
        summary: {
          totalWorkItems: 0,
          withActivity: 0,
          noActivity: 0,
          built: 0,
          missing: 0
        },
        projectCreator: projectData?.createdBy || projectData?.owner || 'You',
        message: 'No MVP checklist generated yet. Click "Regenerate Plan" to create one.'
      });
    }

    // Build lightweight history object with just what we need
    const history = {
      chronologicalEvents: [
        // Add git commits
        ...(git.commits || []).map((commit: any) => ({
          type: 'git_commit',
          timestamp: new Date(commit.date).toISOString(),
          data: {
            hash: commit.hash,
            message: commit.message,
            filesChanged: commit.filesChanged,
            insertions: commit.insertions,
            deletions: commit.deletions
          }
        })),
        // Add extension sessions
        ...(activity.sessions || []).map((session: any) => ({
          type: 'extension_session',
          timestamp: session.startTime,
          data: {
            duration: session.duration,
            filesModified: session.filesModified
          }
        }))
      ]
    };

    // Map pages to work items with session data
    const workItems = [];

    for (const category of checklist.mvpChecklist) {
      for (const item of category.pages) {
        const relatedSessions = findRelatedSessions(item, history);
        const relatedCommits = findRelatedCommits(item, history);

        const hasActivity = relatedSessions.length > 0 || relatedCommits.length > 0;
        const startDate = hasActivity 
          ? getEarliestDate([...relatedSessions, ...relatedCommits])
          : null;
        const endDate = hasActivity
          ? getLatestDate([...relatedSessions, ...relatedCommits])
          : null;

        workItems.push({
          id: `${category.category.toLowerCase().replace(/\s+/g, '-')}-${item.title.toLowerCase().replace(/\s+/g, '-')}`,
          title: item.title,
          category: category.category,
          path: item.path,
          status: item.status,
          priority: item.priority,
          
          startDate,
          endDate,
          duration: calculateDuration(startDate, endDate),
          
          sessionsCount: relatedSessions.length,
          commitsCount: relatedCommits.length,
          totalActivity: relatedSessions.length + relatedCommits.length,
          
          sessions: relatedSessions,
          commits: relatedCommits,
          
          requirements: generateRequirements(item, { name: category.category }),
          
          evidence: item.evidence || [],
          note: item.note
        });
      }
    }

    // Sort by category order and status
    // Priority: Core Features -> Marketing -> Social -> Content -> Settings
    const categoryOrder = [
      'Core Features',
      'Marketing',
      'Social',
      'Content',
      'Settings'
    ];

    workItems.sort((a, b) => {
      // First by category
      const catCompare = categoryOrder.indexOf(a.category) - categoryOrder.indexOf(b.category);
      if (catCompare !== 0) return catCompare;
      
      // Then by status (built first, then in_progress, then missing)
      const statusOrder = { 'built': 0, 'in_progress': 1, 'missing': 2 };
      return (statusOrder[a.status as keyof typeof statusOrder] || 3) - 
             (statusOrder[b.status as keyof typeof statusOrder] || 3);
    });

    // Calculate timeline range
    const allDates = workItems
      .filter(w => w.startDate)
      .flatMap(w => [w.startDate, w.endDate].filter(Boolean))
      .map(d => new Date(d!));

    const timelineStart = allDates.length > 0 
      ? new Date(Math.min(...allDates.map(d => d.getTime())))
      : new Date();
    const timelineEnd = new Date(); // Today

    return NextResponse.json({
      workItems,
      timeline: {
        start: timelineStart.toISOString(),
        end: timelineEnd.toISOString(),
        totalDays: Math.ceil((timelineEnd.getTime() - timelineStart.getTime()) / (1000 * 60 * 60 * 24))
      },
      summary: {
        totalWorkItems: workItems.length,
        withActivity: workItems.filter(w => w.totalActivity > 0).length,
        noActivity: workItems.filter(w => w.totalActivity === 0).length,
        built: workItems.filter(w => w.status === 'built').length,
        missing: workItems.filter(w => w.status === 'missing').length
      },
      projectCreator: projectData?.createdBy || projectData?.owner || 'You'
    });

  } catch (error) {
    console.error('Error generating timeline view:', error);
    return NextResponse.json(
      { 
        error: 'Failed to generate timeline view',
        details: error instanceof Error ? error.message : String(error)
      },
      { status: 500 }
    );
  }
}

function findRelatedSessions(page: any, history: any) {
  const pagePath = page.path.toLowerCase();
  const pageTitle = page.title.toLowerCase();
  
  return history.chronologicalEvents
    .filter((e: any) => e.type === 'extension_session')
    .filter((e: any) => {
      const filesModified = e.data.filesModified || [];
      return filesModified.some((f: string) => {
        const lowerFile = f.toLowerCase();
        return lowerFile.includes(pagePath) || 
               lowerFile.includes(pageTitle.replace(/\s+/g, '-')) ||
               (page.evidence && page.evidence.some((ev: string) => lowerFile.includes(ev.toLowerCase())));
      });
    })
    .map((e: any) => ({
      timestamp: e.timestamp,
      duration: e.data.duration,
      filesModified: e.data.filesModified
    }));
}

function findRelatedCommits(page: any, history: any) {
  const pagePath = page.path.toLowerCase();
  const pageTitle = page.title.toLowerCase();
  
  return history.chronologicalEvents
    .filter((e: any) => e.type === 'git_commit')
    .filter((e: any) => {
      const message = e.data.message.toLowerCase();
      return message.includes(pagePath) || 
             message.includes(pageTitle.replace(/\s+/g, ' ')) ||
             (page.evidence && page.evidence.some((ev: string) => message.includes(ev.toLowerCase())));
    })
    .map((e: any) => ({
      timestamp: e.timestamp,
      hash: e.data.hash,
      message: e.data.message,
      insertions: e.data.insertions,
      deletions: e.data.deletions
    }));
}

function getEarliestDate(events: any[]) {
  if (events.length === 0) return null;
  const dates = events.map(e => new Date(e.timestamp).getTime());
  return new Date(Math.min(...dates)).toISOString();
}

function getLatestDate(events: any[]) {
  if (events.length === 0) return null;
  const dates = events.map(e => new Date(e.timestamp).getTime());
  return new Date(Math.max(...dates)).toISOString();
}

function calculateDuration(startDate: string | null, endDate: string | null): number {
  if (!startDate || !endDate) return 0;
  const diff = new Date(endDate).getTime() - new Date(startDate).getTime();
  return Math.ceil(diff / (1000 * 60 * 60 * 24));
}

function generateRequirements(page: any, category: any): any[] {
  const requirements = [];

  // Generate specific requirements based on page type
  if (page.title.includes('Sign In') || page.title.includes('Sign Up')) {
    requirements.push(
      { id: 1, text: 'Email/password authentication', status: 'built' },
      { id: 2, text: 'GitHub OAuth integration', status: 'built' },
      { id: 3, text: 'Password reset flow', status: 'missing' },
      { id: 4, text: 'Session management', status: 'built' }
    );
  } else if (page.title.includes('Checklist')) {
    requirements.push(
      { id: 1, text: 'Display generated tasks from API', status: 'missing' },
      { id: 2, text: 'Mark tasks as complete', status: 'missing' },
      { id: 3, text: 'Drag-and-drop reordering', status: 'missing' },
      { id: 4, text: 'Save checklist state', status: 'missing' },
      { id: 5, text: 'Export to markdown/PDF', status: 'missing' }
    );
  } else if (page.title.includes('Vision') || page.title.includes('Mission')) {
    requirements.push(
      { id: 1, text: 'Capture product vision text', status: 'missing' },
      { id: 2, text: 'AI-assisted vision refinement', status: 'missing' },
      { id: 3, text: 'Upload supporting documents', status: 'missing' },
      { id: 4, text: 'Save vision to project metadata', status: 'built' }
    );
  } else if (page.title.includes('Marketing Automation')) {
    requirements.push(
      { id: 1, text: 'Connect to /plan/marketing API', status: 'missing' },
      { id: 2, text: 'Generate landing page copy', status: 'missing' },
      { id: 3, text: 'Generate email sequences', status: 'missing' },
      { id: 4, text: 'Export marketing materials', status: 'missing' }
    );
  } else if (page.title.includes('Communication Automation')) {
    requirements.push(
      { id: 1, text: 'Email template builder', status: 'missing' },
      { id: 2, text: 'Slack integration', status: 'missing' },
      { id: 3, text: 'Automated project updates', status: 'missing' },
      { id: 4, text: 'Team notifications', status: 'missing' }
    );
  } else if (page.title.includes('Import') && page.title.includes('Modal')) {
    requirements.push(
      { id: 1, text: 'Start from scratch option', status: 'built' },
      { id: 2, text: 'Import from GitHub', status: 'built' },
      { id: 3, text: 'Import from local folder', status: 'missing' },
      { id: 4, text: 'Auto-detect project type', status: 'missing' },
      { id: 5, text: 'Trigger Cursor import', status: 'built' },
      { id: 6, text: 'Create .vibn file', status: 'built' }
    );
  } else if (page.status === 'built') {
    requirements.push(
      { id: 1, text: 'Page built and accessible', status: 'built' },
      { id: 2, text: 'Connected to backend API', status: 'built' }
    );
  } else {
    requirements.push(
      { id: 1, text: 'Design page layout', status: 'missing' },
      { id: 2, text: 'Implement core functionality', status: 'missing' },
      { id: 3, text: 'Connect to backend API', status: 'missing' },
      { id: 4, text: 'Add error handling', status: 'missing' }
    );
  }

  return requirements;
}