import { type NextRequest, NextResponse } from "next/server"

// Utility function to generate UUID with fallback
const generateUUID = (): string => {
  // Check if crypto.randomUUID is available
  if (typeof crypto !== 'undefined' && crypto.randomUUID) {
    try {
      return crypto.randomUUID();
    } catch (error) {
      console.warn('crypto.randomUUID failed, using fallback:', error);
    }
  }
  
  // Fallback UUID generation
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    const r = Math.random() * 16 | 0;
    const v = c == 'x' ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
};

// Create a more persistent storage mechanism (still in-memory but more reliable)
// This will be a global variable that persists between API calls
// In a production environment, you would use a database instead
const graphDataStore = new Map<string, { triples: any[]; documentName: string }>()

// Sample graph data for when no ID is provided
const sampleGraphData = {
  nodes: [
    { id: "1", name: "Document 1", group: "document" },
    { id: "2", name: "Machine Learning", group: "concept" },
    { id: "3", name: "Neural Networks", group: "concept" },
    { id: "4", name: "Deep Learning", group: "concept" },
    { id: "5", name: "Computer Vision", group: "concept" },
    { id: "6", name: "Natural Language Processing", group: "concept" },
    { id: "7", name: "Reinforcement Learning", group: "concept" },
    { id: "8", name: "Supervised Learning", group: "concept" },
    { id: "9", name: "Unsupervised Learning", group: "concept" },
    { id: "10", name: "Semi-supervised Learning", group: "concept" },
    { id: "11", name: "Transfer Learning", group: "concept" },
    { id: "12", name: "GPT-4", group: "important" },
    { id: "13", name: "BERT", group: "concept" },
    { id: "14", name: "Transformers", group: "concept" },
    { id: "15", name: "CNN", group: "concept" },
    { id: "16", name: "RNN", group: "concept" },
    { id: "17", name: "LSTM", group: "concept" },
    { id: "18", name: "GAN", group: "concept" },
    { id: "19", name: "Diffusion Models", group: "important" },
    { id: "20", name: "Document 2", group: "document" },
  ],
  links: [
    { source: "1", target: "2", name: "mentions" },
    { source: "1", target: "3", name: "discusses" },
    { source: "1", target: "4", name: "explains" },
    { source: "2", target: "3", name: "includes" },
    { source: "2", target: "4", name: "includes" },
    { source: "2", target: "5", name: "related_to" },
    { source: "2", target: "6", name: "related_to" },
    { source: "2", target: "7", name: "includes" },
    { source: "2", target: "8", name: "includes" },
    { source: "2", target: "9", name: "includes" },
    { source: "2", target: "10", name: "includes" },
    { source: "2", target: "11", name: "includes" },
    { source: "3", target: "15", name: "includes" },
    { source: "3", target: "16", name: "includes" },
    { source: "3", target: "17", name: "includes" },
    { source: "4", target: "12", name: "uses" },
    { source: "4", target: "13", name: "uses" },
    { source: "4", target: "14", name: "uses" },
    { source: "6", target: "12", name: "uses" },
    { source: "6", target: "13", name: "uses" },
    { source: "6", target: "14", name: "uses" },
    { source: "5", target: "15", name: "uses" },
    { source: "5", target: "18", name: "uses" },
    { source: "5", target: "19", name: "uses" },
    { source: "20", target: "6", name: "mentions" },
    { source: "20", target: "12", name: "discusses" },
    { source: "20", target: "19", name: "explains" },
  ]
};

export async function POST(request: NextRequest) {
  try {
    const { triples, documentName } = await request.json()

    if (!triples || !Array.isArray(triples)) {
      return NextResponse.json({ error: "Invalid triples data" }, { status: 400 })
    }

    // Generate a unique ID for this graph data
    const graphId = generateUUID()

    // Store the data
    graphDataStore.set(graphId, { triples, documentName: documentName || "Unnamed Document" })

    console.log(`Stored graph data with ID: ${graphId}, triples count: ${triples.length}`)

    // Return the ID
    return NextResponse.json({ graphId })
  } catch (error) {
    console.error("Error storing graph data:", error)
    return NextResponse.json({ error: "Failed to store graph data" }, { status: 500 })
  }
}

export async function GET(request: NextRequest) {
  try {
    const url = new URL(request.url)
    const graphId = url.searchParams.get("id")

    // If no ID provided, return sample graph data
    if (!graphId) {
      console.log("No graph ID provided, returning sample data")
      return NextResponse.json(sampleGraphData)
    }

    console.log(`Retrieving graph data for ID: ${graphId}`)
    console.log(`Available graph IDs: ${Array.from(graphDataStore.keys()).join(", ")}`)

    const graphData = graphDataStore.get(graphId)

    if (!graphData) {
      console.log(`Graph data not found for ID: ${graphId}. Informing client to use localStorage.`)
      // Instead of a redirect, return a special response that tells the client to use localStorage
      return NextResponse.json({ 
        redirect: true, 
        useLocalStorage: true,
        error: "Graph data not found or has expired"
      }, { status: 404 })
    }

    console.log(`Found graph data with ${graphData.triples.length} triples`)
    return NextResponse.json(graphData)
  } catch (error) {
    console.error("Error retrieving graph data:", error)
    return NextResponse.json({ error: "Failed to retrieve graph data" }, { status: 500 })
  }
}