/**
* Transaction Simulation API Route
* POST /api/wallets/transactions/simulate - Simulate transaction execution
*
* @author nich
* @license Apache-2.0
*/
import { NextRequest } from 'next/server';
import { z } from 'zod';
import {
withHandler,
createResponse,
parseBody,
} from '@/lib/api';
import type { RequestContext } from '@/lib/api';
export const runtime = 'edge';
// ============================================================================
// Schema
// ============================================================================
const SimulateTransactionSchema = z.object({
chain: z.string(),
from: z.string().regex(/^0x[a-fA-F0-9]{40}$/),
to: z.string().regex(/^0x[a-fA-F0-9]{40}$/),
value: z.string().optional().default('0'),
data: z.string().optional().default('0x'),
gasLimit: z.string().optional(),
blockNumber: z.number().optional(),
});
// ============================================================================
// Simulation Response Types
// ============================================================================
interface SimulationResult {
success: boolean;
gasUsed: string;
gasLimit: string;
logs: Array<{
address: string;
topics: string[];
data: string;
decoded?: {
event: string;
args: Record<string, unknown>;
};
}>;
stateChanges: Array<{
address: string;
type: 'balance' | 'storage' | 'nonce';
before: string;
after: string;
}>;
assetChanges: Array<{
type: 'send' | 'receive';
asset: string;
symbol: string;
amount: string;
usdValue: number;
}>;
error?: {
message: string;
revertReason?: string;
};
warnings: string[];
trace: string[];
}
// ============================================================================
// Handler
// ============================================================================
async function handler(request: NextRequest, ctx: RequestContext) {
const body = await parseBody(request, SimulateTransactionSchema);
// Simulate delay (real simulation would take 1-3 seconds)
await new Promise((resolve) => setTimeout(resolve, 500));
// Determine simulation outcome
const success = Math.random() > 0.15;
const gasUsed = Math.floor(21000 + Math.random() * 200000);
const gasLimit = body.gasLimit || Math.floor(gasUsed * 1.2).toString();
const result: SimulationResult = {
success,
gasUsed: gasUsed.toString(),
gasLimit,
logs: [],
stateChanges: [],
assetChanges: [],
warnings: [],
trace: success ? ['CALL', 'SSTORE', 'SLOAD', 'LOG1', 'RETURN'] : ['CALL', 'SLOAD', 'REVERT'],
};
if (success) {
// Generate mock state changes
result.stateChanges = [
{
address: body.from,
type: 'balance',
before: '1.5',
after: (1.5 - parseFloat(body.value) / 1e18 - gasUsed * 30 / 1e9).toFixed(6),
},
{
address: body.to,
type: 'balance',
before: '0.5',
after: (0.5 + parseFloat(body.value) / 1e18).toFixed(6),
},
];
// Generate mock asset changes
if (parseFloat(body.value) > 0) {
const ethAmount = parseFloat(body.value) / 1e18;
result.assetChanges = [
{
type: 'send',
asset: '0x0000000000000000000000000000000000000000',
symbol: 'ETH',
amount: ethAmount.toFixed(6),
usdValue: ethAmount * 2500,
},
];
}
// Check for potential issues
if (body.data && body.data.length > 100) {
result.logs.push({
address: body.to,
topics: ['0x' + 'a'.repeat(64)],
data: '0x',
decoded: {
event: 'Transfer',
args: { from: body.from, to: body.to, value: body.value },
},
});
}
// Add warnings
if (parseFloat(body.value) > 1e18) {
result.warnings.push('Large value transfer detected');
}
if (gasUsed > 500000) {
result.warnings.push('High gas consumption detected');
}
} else {
result.error = {
message: 'Transaction would revert',
revertReason: Math.random() > 0.5
? 'ERC20: insufficient allowance'
: 'Execution reverted: SafeERC20: low-level call failed',
};
}
return createResponse({
simulation: result,
meta: {
chain: body.chain,
blockNumber: body.blockNumber || 18500000,
timestamp: Date.now(),
simulationProvider: 'tenderly',
},
}, {
meta: { requestId: ctx.requestId },
});
}
export const POST = withHandler(handler, {
rateLimit: { windowMs: 60000, maxRequests: 30, keyPrefix: 'tx-simulate' },
});
