// test/MyContract.t.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {Test, console} from "forge-std/Test.sol";
import {MyToken} from "../src/MyToken.sol";

contract MyTokenTest is Test {
    MyToken public token;
    address public alice = makeAddr("alice");
    address public bob = makeAddr("bob");

    function setUp() public {
        token = new MyToken("Test", "TST", 1_000_000e18);
        // Give alice some tokens for testing
        token.transfer(alice, 10_000e18);
    }

    function test_TransferUpdatesBalances() public {
        vm.prank(alice);
        token.transfer(bob, 1_000e18);

        assertEq(token.balanceOf(alice), 9_000e18);
        assertEq(token.balanceOf(bob), 1_000e18);
    }

    function test_TransferEmitsEvent() public {
        vm.expectEmit(true, true, false, true);
        emit Transfer(alice, bob, 500e18);

        vm.prank(alice);
        token.transfer(bob, 500e18);
    }

    function test_RevertWhen_TransferExceedsBalance() public {
        vm.prank(alice);
        vm.expectRevert();
        token.transfer(bob, 999_999e18); // More than alice has
    }

    function test_RevertWhen_TransferToZeroAddress() public {
        vm.prank(alice);
        vm.expectRevert();
        token.transfer(address(0), 100e18);
    }
}

// Equality
assertEq(actual, expected);
assertEq(actual, expected, "descriptive error message");

// Comparisons
assertGt(a, b);   // a > b
assertGe(a, b);   // a >= b
assertLt(a, b);   // a < b
assertLe(a, b);   // a <= b

// Approximate equality (for math with rounding)
assertApproxEqAbs(actual, expected, maxDelta);
assertApproxEqRel(actual, expected, maxPercentDelta); // in WAD (1e18 = 100%)

// Revert expectations
vm.expectRevert();                           // Any revert
vm.expectRevert("Insufficient balance");     // Specific message
vm.expectRevert(MyContract.CustomError.selector); // Custom error

// Event expectations
vm.expectEmit(true, true, false, true);      // (topic1, topic2, topic3, data)
emit MyEvent(expectedArg1, expectedArg2);

// ✅ TEST: Edge cases that lose money
function test_TransferZeroAmount() public { /* ... */ }
function test_TransferEntireBalance() public { /* ... */ }
function test_TransferToSelf() public { /* ... */ }
function test_ApproveOverwrite() public { /* ... */ }
function test_TransferFromWithExactAllowance() public { /* ... */ }

// ✅ TEST: Access control
function test_RevertWhen_NonOwnerCallsAdminFunction() public { /* ... */ }
function test_OwnerCanPause() public { /* ... */ }

// ✅ TEST: Failure modes
function test_RevertWhen_DepositZero() public { /* ... */ }
function test_RevertWhen_WithdrawMoreThanDeposited() public { /* ... */ }
function test_RevertWhen_ContractPaused() public { /* ... */ }

// ❌ DON'T TEST: OpenZeppelin internals
// function test_NameReturnsName() — they already tested this
// function test_SymbolReturnsSymbol() — waste of time
// function test_DecimalsReturns18() — it does, trust it

// Foundry calls this with random amounts
function testFuzz_DepositWithdrawRoundtrip(uint256 amount) public {
    // Bound input to valid range
    amount = bound(amount, 1, token.balanceOf(alice));

    uint256 balanceBefore = token.balanceOf(alice);

    vm.startPrank(alice);
    token.approve(address(vault), amount);
    vault.deposit(amount, alice);
    vault.withdraw(vault.balanceOf(alice), alice, alice);
    vm.stopPrank();

    // Property: user gets back what they deposited (minus any fees)
    assertGe(token.balanceOf(alice), balanceBefore - 1); // Allow 1 wei rounding
}

// bound() is preferred over vm.assume() — bound reshapes, assume discards
function testFuzz_Fee(uint256 amount, uint256 feeBps) public {
    amount = bound(amount, 1e6, 1e30);       // Reasonable token amounts
    feeBps = bound(feeBps, 1, 10_000);       // 0.01% to 100%

    uint256 fee = (amount * feeBps) / 10_000;
    uint256 afterFee = amount - fee;

    // Property: fee + remainder always equals original
    assertEq(fee + afterFee, amount);
}

// vm.assume() discards inputs — use sparingly
function testFuzz_Division(uint256 a, uint256 b) public {
    vm.assume(b > 0); // Skip zero (would revert)
    // ...
}

undefined

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contract SwapTest is Test {
    // Real mainnet addresses
    address constant UNISWAP_ROUTER = 0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45;
    address constant WETH = 0xC02aaA39b223FE8D0A0e5d4F533d69895b411153;
    address constant USDC = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;

    function setUp() public {
        // Fork mainnet at a specific block for reproducibility
        vm.createSelectFork("mainnet", 19_000_000);
    }

    function test_SwapETHForUSDC() public {
        address user = makeAddr("user");
        vm.deal(user, 1 ether);

        vm.startPrank(user);

        // Build swap path
        ISwapRouter.ExactInputSingleParams memory params = ISwapRouter
            .ExactInputSingleParams({
                tokenIn: WETH,
                tokenOut: USDC,
                fee: 3000,
                recipient: user,
                amountIn: 0.1 ether,
                amountOutMinimum: 0, // In production, NEVER set to 0
                sqrtPriceLimitX96: 0
            });

        // Execute swap
        uint256 amountOut = ISwapRouter(UNISWAP_ROUTER).exactInputSingle{value: 0.1 ether}(params);

        vm.stopPrank();

        // Verify we got USDC back
        assertGt(amountOut, 0, "Should receive USDC");
        assertGt(IERC20(USDC).balanceOf(user), 0);
    }
}

undefined

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contract VaultInvariantTest is Test {
    MyVault public vault;
    IERC20 public token;
    VaultHandler public handler;

    function setUp() public {
        token = new MockERC20("Test", "TST", 18);
        vault = new MyVault(token);
        handler = new VaultHandler(vault, token);

        // Tell Foundry which contract to call randomly
        targetContract(address(handler));
    }

    // This runs after every random sequence
    function invariant_TotalAssetsMatchesBalance() public view {
        assertEq(
            vault.totalAssets(),
            token.balanceOf(address(vault)),
            "Total assets must equal actual balance"
        );
    }

    function invariant_SharePriceNeverZero() public view {
        if (vault.totalSupply() > 0) {
            assertGt(vault.convertToAssets(1e18), 0, "Share price must never be zero");
        }
    }
}

// Handler: guided random actions
contract VaultHandler is Test {
    MyVault public vault;
    IERC20 public token;

    constructor(MyVault _vault, IERC20 _token) {
        vault = _vault;
        token = _token;
    }

    function deposit(uint256 amount) public {
        amount = bound(amount, 1, 1e24);
        deal(address(token), msg.sender, amount);

        vm.startPrank(msg.sender);
        token.approve(address(vault), amount);
        vault.deposit(amount, msg.sender);
        vm.stopPrank();
    }

    function withdraw(uint256 shares) public {
        uint256 maxShares = vault.balanceOf(msg.sender);
        if (maxShares == 0) return;
        shares = bound(shares, 1, maxShares);

        vm.prank(msg.sender);
        vault.redeem(shares, msg.sender, msg.sender);
    }
}

undefined

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