Modernize the PSM and add negative fees

.gitignore

@@ -1 +1,2 @@
-/out
+cache/
+out/

.gitmodules

@@ -1,9 +1,6 @@
-[submodule "lib/ds-test"]
-	path = lib/ds-test
-	url = https://github.com/dapphub/ds-test
-[submodule "lib/dss-interfaces"]
-	path = lib/dss-interfaces
-	url = https://github.com/makerdao/dss-interfaces
-[submodule "lib/dss"]
-	path = lib/dss
-	url = https://github.com/makerdao/dss
+[submodule "lib/dss-test"]
+	path = lib/dss-test
+	url = https://github.com/makerdao/dss-test
+[submodule "lib/ds-value"]
+	path = lib/ds-value
+	url = https://github.com/dapphub/ds-value

Makefile

@@ -1,3 +1,3 @@
-all    :; dapp --use solc:0.6.12 build
-clean  :; dapp clean
+all    :; forge build --use solc:0.8.14
+clean  :; forge clean
 test   :; ./test.sh $(match)

README.md

@@ -1,38 +1,28 @@
-# DssPsm
+# dss-psm
 
-The official implementation of the [Peg Stability Module](https://forum.makerdao.com/t/mip29-peg-stability-module/5071). There are two main components to the PSM:
+The official implementation of the [Peg Stability Module](https://forum.makerdao.com/t/mip29-peg-stability-module/5071).
 
-### AuthGemJoinX
+### Psm
 
-This is an exact duplicate of the `GemJoinX` adapter for the given collateral type with two modifications.
+`Psm` allows you to either call `sellGem()` or `buyGem()` to trade ERC20 DAI for the gem or vice versa. Upon calling one of these functions the PSM vault will either lock gems in the join adapter, take out a dai loan and issue ERC20 DAI to the specified user or do that process in reverse.
 
-First the method signature of `join()` is changed to include the original message sender at the end as well as adding the `auth` modifier. This should look like:
-
-`function join(address urn, uint256 wad) external note` -> `function join(address urn, uint256 wad, address _msgSender) external note auth`
-
-Second, all instances of `msg.sender` are replaced with `_msgSender` in the `join()` function.
-
-In this repository I have added [join-5-auth.sol](https://github.com/BellwoodStudios/dss-psm/blob/master/src/join-5-auth.sol) for the PSM-friendly version of [join-5.sol](https://github.com/makerdao/dss-gem-joins/blob/master/src/join-5.sol) which is used for USDC. This can be applied to any other gem join adapter.
-
-### DssPsm
-
-This is the actual PSM module which acts as a authed special vault sitting behind the `AuthGemJoinX` contract. `DssPsm` allows you to either call `sellGem()` or `buyGem()` to trade ERC20 DAI for the gem or vice versa. Upon calling one of these functions the PSM vault will either lock gems in the join adapter, take out a dai loan and issue ERC20 DAI to the specified user or do that process in reverse.
+`Psm` can charge either a positive or negative fee in both directions. Positive fees correspond to the user paying the protocol for using the PSM. Negative fees correspond to the protocol paying the user for using the PSM.
 
 #### Approvals
 
 The PSM requires ERC20 approvals to pull in the tokens.
 
-To use `sellGem(usr, amt)` you must first call `gem.approve(<gemJoinAddress>, amt)`. Example:
+To use `sellGem(usr, amt)` you must first call `gem.approve(<psmAddress>, amt)`. Example:
 
     // Trade 100 USDC for 100 DAI - fee
-    usdc.approve(0x0A59649758aa4d66E25f08Dd01271e891fe52199, 100 * (10 ** 6));
+    usdc.approve(<psmAddress>, 100 * (10 ** 6));
     psm.sellGem(address(this), 100 * (10 ** 6));
 
 To use `buyGem(usr, amt)` you must first call `dai.approve(<psmAddress>, amt + fee)`. Example:
 
     // Trade DAI + fee for 100 USDC
     uint256 WAD = 10 ** 18;
-    dai.approve(0x89B78CfA322F6C5dE0aBcEecab66Aee45393cC5A, 100 * (psm.tout() + WAD));
+    dai.approve(<psmAddress>, 100 * (psm.tout() + WAD));
     psm.buyGem(address(this), 100 * (10 ** 6));
 
 #### Notes on Fees
@@ -45,7 +35,7 @@ When calling `buyGem()`, you specify the amount of the gem you want to recieve.
 
 Please note this was a conscious decision to avoid dealing with decimal division and rounding leftovers. 
 
-## Contracts
+## Old Contracts [V1]
 
 ### Mainnet
 
@@ -57,4 +47,4 @@ USDP PSM: [0x961Ae24a1Ceba861D1FDf723794f6024Dc5485Cf](https://etherscan.io/addr
 ### Kovan
 
 USDC GemJoin: [0x4BA159Ad37FD80D235b4a948A8682747c74fDc0E](https://kovan.etherscan.io/address/0x4BA159Ad37FD80D235b4a948A8682747c74fDc0E#code)  
-USDC PSM: [0xe4dC42e438879987e287A6d9519379936d7b065A](https://kovan.etherscan.io/address/0xe4dC42e438879987e287A6d9519379936d7b065A#code)  
+USDC PSM: [0xe4dC42e438879987e287A6d9519379936d7b065A](https://kovan.etherscan.io/address/0xe4dC42e438879987e287A6d9519379936d7b065A#code)  

foundry.toml

@@ -0,0 +1,7 @@
+[profile.default]
+src = 'src'
+out = 'out'
+libs = ['lib']
+remappings = ['dss-test/=lib/dss-test/src/']
+
+# See more config options https://github.com/gakonst/foundry/tree/master/config