Use bigint for handling token price

src/app/api/flux/route.ts

@@ -3,7 +3,8 @@ import { fal } from "@fal-ai/client"
 import { FLUX_MODELS } from '../../../services/fluxService'
 import { initializeDataSource } from '../../../data-source'
 
-import { verifyPayment, isSignatureUsed, markSignatureAsUsed } from '../../../utils/verifyPayment'
+import { verifyPayment, markSignatureAsUsed } from '../../../utils/verifyPayment'
+import { getUSDCToMTMQuote } from '../../../services/paymentService'
 
 if (!process.env.FAL_AI_KEY) {
   throw new Error('FAL_AI_KEY is not configured in environment variables')
@@ -46,7 +47,13 @@ export async function POST(req: NextRequest): Promise<NextResponse> {
       )
     }
 
-    const expectedAmount = model.cost;
+    const MTMFor1USDC = await getUSDCToMTMQuote();
+
+    // TODO: Use bn.js for better precision
+    const scale = BigInt(100);
+    const scaledCost = BigInt(Math.round(model.cost * Number(scale)));
+
+    const expectedAmount = (scaledCost * MTMFor1USDC) / scale;
     const isPaymentVerified = await verifyPayment(transactionSignature, expectedAmount)
 
     if (!isPaymentVerified) {

src/app/page.tsx

@@ -15,14 +15,13 @@ const Page: React.FC = (): React.ReactElement => {
     type: null
   })
 
-  const [usdcPrice, setUsdcPrice] = useState<number>(0);
+  const [MTMFor1USDC, setMTMFor1USDC] = useState<bigint>(BigInt(0));
 
   useEffect(() => {
-
     const fetchPrice = async () => {
       try {
         const price = await getUSDCToMTMQuote();
-        setUsdcPrice(price);
+        setMTMFor1USDC(price);
       } catch (error) {
         console.error('Failed to fetch price:', error);
       }
@@ -55,24 +54,26 @@ const Page: React.FC = (): React.ReactElement => {
         connected: false,
         publicKey: null,
         type: null
-      })
+      });
-    }
     }
+  };
 
-  const handleFluxGeneration = (modelId: string, cost: number) => {
+  const handleFluxGeneration = (modelId: string, cost: bigint) => {
     return async (prompt: string): Promise<FluxGenerationResult> => {
-      const type = walletState.type;
+      const { connected, publicKey, type } = walletState;
-      if (!walletState.connected || !walletState.publicKey || !walletState.type ||
+
+      if (!connected || !publicKey || !type ||
         (type === 'phantom' && !window.phantom) ||
         (type === 'solflare' && !window.solflare)) {
         return { error: 'Wallet not connected' }
       }
 
-      // Process payment first
+      try {
+        // Convert cost in USDC to MTM tokens using the price ratio
         const paymentResult = await processMTMPayment(
-        walletState.publicKey,
+          publicKey,
           cost,
-	      walletState.type
+          type
         )
 
         if (!paymentResult.success) {
@@ -85,8 +86,12 @@ const Page: React.FC = (): React.ReactElement => {
           return { error: 'Transaction signature not found' }
         }
 
-      // Then generate image with specified model
+        // Generate image with specified model and transaction reference
         return generateWithFlux(prompt, modelId, transactionSignature)
+      } catch (error) {
+        console.error('Error in handleFluxGeneration:', error)
+        return { error: error instanceof Error ? error.message : 'Unknown error' }
+      }
     }
   }
 
@@ -116,10 +121,23 @@ const Page: React.FC = (): React.ReactElement => {
               key={model.modelId}
               title={model.name}
               description={model.description}
-              tokenCost={model.cost}
               isWalletConnected={walletState.connected}
-              onGenerate={handleFluxGeneration(model.modelId, model.cost)}
+              // TODO: Use bn.js for better precision
-              mtmPrice={model.cost * usdcPrice}
+              onGenerate={handleFluxGeneration(
+                model.modelId,
+                (() => {
+                  const scale = BigInt(100); // Scaling factor
+                  const scaledCost = BigInt(Math.round(model.cost * Number(scale)));
+                  const scaledResult = (scaledCost * MTMFor1USDC) / scale;
+                  return scaledResult;
+                })()
+              )}
+              // TODO: Use bn.js for better precision
+              mtmPrice={(() => {
+                const scale = BigInt(100);
+                const scaledCost = BigInt(Math.round(model.cost * Number(scale)));
+                return (scaledCost * MTMFor1USDC) / scale;
+              })()}
           />
           ))}
 

src/components/AIServiceCard.tsx

@@ -5,10 +5,9 @@ import React, { useState } from 'react'
 interface AIServiceCardProps {
   title: string
   description: string
-  tokenCost: number
   isWalletConnected: boolean
   onGenerate: (prompt: string) => Promise<{ imageUrl?: string, error?: string }>
-  mtmPrice: number | null
+  mtmPrice: bigint
 }
 
 interface GenerationState {
@@ -21,7 +20,6 @@ interface GenerationState {
 const AIServiceCard: React.FC<AIServiceCardProps> = ({
   title,
   description,
-  tokenCost,
   isWalletConnected,
   onGenerate,
   mtmPrice
@@ -83,7 +81,7 @@ const AIServiceCard: React.FC<AIServiceCardProps> = ({
           </h2>
           <p className="text-gray-400 mt-2">{description}</p>
           <div className="mt-2 inline-block px-3 py-1 bg-green-500/20 rounded-full text-green-300 text-sm">
-            Cost: {mtmPrice ?  mtmPrice.toFixed(2) : '...'} MTM
+            Cost: {mtmPrice ? (mtmPrice / BigInt(10 ** 6)).toString() : '...'} MTM
           </div>
         </div>
 
@@ -107,7 +105,7 @@ const AIServiceCard: React.FC<AIServiceCardProps> = ({
                      transition-all duration-200 shadow-lg hover:shadow-green-500/25
                      disabled:opacity-50 disabled:cursor-not-allowed disabled:hover:shadow-none"
           >
-            {generationState.loading ? 'Processing...' : `Pay ${mtmPrice ?  mtmPrice.toFixed(2) : '...'} MTM & Generate`}
+            {generationState.loading ? 'Processing...' : `Pay ${mtmPrice ? (mtmPrice / BigInt(10 ** 6)).toString() : '...'} MTM & Generate`}
           </button>
         </div>
 

src/services/fluxService.ts

@@ -16,19 +16,19 @@ export const FLUX_MODELS: FluxModelConfig[] = [
     modelId: "fal-ai/flux/schnell",
     name: "Schnell",
     description: "Fast meme generator",
-    cost: 0.1
+    cost: 0.05
   },
   {
     modelId: "fal-ai/recraft-v3",
     name: "Recraft",
     description: "Advanced meme generator",
-    cost: 0.15
+    cost: 0.10
   },
   {
     modelId: "fal-ai/stable-diffusion-v35-large",
     name: "Marquee",
     description: "Best meme generator",
-    cost: 0.2
+    cost: 0.15
   }
 ]
 

src/services/paymentService.ts

@@ -60,8 +60,10 @@ export async function getUSDCToMTMQuote() {
   }
 
   const quoteResponse = await response.json();
-  const price = quoteResponse['data'][USDC_MINT]['price']
 
+  // TODO: Use bn.js for better precision
+  const priceFromAPI = Number(quoteResponse['data'][USDC_MINT]['price'])* (10 ** 6);
+  const price = BigInt(Number(priceFromAPI.toFixed(0)));
   return price;
 }
 
@@ -71,7 +73,7 @@ interface WalletAdapter {
 
 export async function processMTMPayment(
   walletPublicKey: string,
-  tokenAmount: number,
+  tokenAmount: bigint,
   walletType: WalletType
 ): Promise<PaymentResult> {
   try {
@@ -143,12 +145,14 @@ export async function processMTMPayment(
       )
     }
 
+    const tokens = tokenAmount / BigInt(10 ** 6);
+
     transaction.add(
       createTransferInstruction(
         senderATA,
         receiverATA,
         senderPublicKey,
-        BigInt(tokenAmount * (10 ** 6))
+        tokens * BigInt(10 ** 6)
       )
     )
 
@@ -157,7 +161,7 @@ export async function processMTMPayment(
     transaction.feePayer = senderPublicKey
 
     console.log('Sending transaction...')
-    const { signature } = await wallet.signAndSendTransaction(transaction)
+    const { signature } = await wallet.signAndSendTransaction(transaction);
     console.log('Transaction sent:', signature)
 
     const confirmation = await connection.confirmTransaction({

src/utils/verifyPayment.ts

@@ -1,9 +1,13 @@
+import assert from 'assert';
+
 import { Connection } from '@solana/web3.js';
 import { TOKEN_PROGRAM_ID } from '@solana/spl-token';
 
 import { AppDataSource } from '../data-source';
 import { Payment } from '../entity/Payment';
 
+assert(process.env.NEXT_PUBLIC_SOLANA_RPC_URL, 'SOLANA_RPC_URL is required');
+
 const SOLANA_RPC_URL = process.env.NEXT_PUBLIC_SOLANA_RPC_URL;
 const SOLANA_WEBSOCKET_URL = process.env.NEXT_PUBLIC_SOLANA_WEBSOCKET_URL;
 
@@ -42,7 +46,7 @@ export async function markSignatureAsUsed(transactionSignature: string): Promise
 
 export async function verifyPayment(
   transactionSignature: string,
-  expectedAmount: number,
+  expectedAmount: bigint,
 ): Promise<boolean> {
   try {
     // Check if the signature is already used
@@ -67,7 +71,14 @@ export async function verifyPayment(
     const { info } = parsed;
     const { amount } = info;
 
-    if (BigInt(amount) === BigInt(expectedAmount * (10 ** 6))) {
+    const transactionAmount = BigInt(amount);
+    const expectedAmountInMicroTokens = expectedAmount;
+
+    const lowerBound = expectedAmountInMicroTokens * BigInt(9) / BigInt(10);
+    const upperBound = expectedAmountInMicroTokens * BigInt(11) / BigInt(10);
+
+    // transaction within the appropriate range
+    if (transactionAmount >= lowerBound && transactionAmount <= upperBound) {
       return true;
     }