Decentralized Exchanges (DEX)

near view v2.ref-finance.near get_deposits '{"account_id": "bob.near"}'

// Validator interface, for cross-contract calls
#[ext_contract(ext_amm_contract)]
trait ExternalAmmContract {
fn get_deposits(&self, account_id: AccountId) -> Promise;
}

// Implement the contract structure
#[near]
impl Contract {
#[private] // Public - but only callable by env::current_account_id()
pub fn external_get_deposits_callback(&self, #[callback_result] call_result: Result<HashMap<AccountId, U128>, PromiseError>) -> Option<HashMap<AccountId, U128>> {
// Check if the promise succeeded
if call_result.is_err() {
  log!("There was an error contacting external contract");
  return None;
}

// Return the pools data
let deposits_data = call_result.unwrap();
return Some(deposits_data);
}

pub fn get_contract_deposits(&self) -> Promise {
let promise = ext_amm_contract::ext(self.amm_contract.clone())
  .get_deposits(env::current_account_id());

return promise.then( // Create a promise to callback query_greeting_callback
  Self::ext(env::current_account_id())
  .external_get_deposits_callback()
)
}
}

near view v2.ref-finance.near get_pools '{"from_index": 0, "limit": 1000}'

#[near(serializers = [json])]
pub struct PoolInfo {
  /// Pool kind.
  pub pool_kind: String,
  /// List of tokens in the pool.
  pub token_account_ids: Vec<AccountId>,
  /// How much NEAR this contract has.
  pub amounts: Vec<U128>,
  /// Fee charged for swap.
  pub total_fee: u32,
  /// Total number of shares.
  pub shares_total_supply: U128,
  pub amp: u64,
}

// Validator interface, for cross-contract calls
#[ext_contract(ext_amm_contract)]
trait ExternalAmmContract {
  fn get_pools(&self, from_index: u64, limit: u64) -> Promise;
}

// Implement the contract structure
#[near]
impl Contract {
  #[private] // Public - but only callable by env::current_account_id()
  pub fn external_get_pools_callback(&self, #[callback_result] call_result: Result<Vec<PoolInfo>, PromiseError>) -> Option<Vec<PoolInfo>> {
    // Check if the promise succeeded
    if call_result.is_err() {
      log!("There was an error contacting external contract");
      return None;
    }

    // Return the pools data
    let pools_data = call_result.unwrap();
    return Some(pools_data);
  }

  pub fn get_amm_pools(&self, from_index: u64, limit: u64) -> Promise {
    let promise = ext_amm_contract::ext(self.amm_contract.clone())
      .get_pools(from_index, limit);

    return promise.then( // Create a promise to callback query_greeting_callback
      Self::ext(env::current_account_id())
      .external_get_pools_callback()
    )
  }
}

near call v2.ref-finance.near swap "{\"actions\": [{\"pool_id\": 79, \"token_in\": \"token.v2.ref-finance.near\", \"amount_in\": \"100000000000000000\", \"token_out\": \"wrap.near\", \"min_amount_out\": \"1\"}]}" --gas 300000000000000 --depositYocto 1
--useAccount bob.near

#[near(serializers = [json])]
pub struct SwapAction {
    /// Pool which should be used for swapping.
    pub pool_id: u64,
    /// Token to swap from.
    pub token_in: AccountId,
    /// Amount to exchange.
    /// If amount_in is None, it will take amount_out from previous step.
    /// Will fail if amount_in is None on the first step.
    pub amount_in: Option<U128>,
    /// Token to swap into.
    pub token_out: AccountId,
    /// Required minimum amount of token_out.
    pub min_amount_out: U128,
}

// Validator interface, for cross-contract calls
#[ext_contract(ext_amm_contract)]
trait ExternalAmmContract {
  fn swap(&self, actions: Vec<SwapAction>) -> Promise;
}

// Implement the contract structure
#[near]
impl Contract {
  #[private] // Public - but only callable by env::current_account_id()
  pub fn external_call_callback(&self, #[callback_result] call_result: Result<String, PromiseError>) {
    // Check if the promise succeeded
    if call_result.is_err() {
      log!("There was an error contacting external contract");
    }
  }

  #[payable]
  pub fn swap_tokens(&mut self, pool_id: u64, token_in: AccountId, token_out: AccountId, amount_in: U128, min_amount_out: U128) -> Promise {
    assert_eq!(env::attached_deposit(), 1, "Requires attached deposit of exactly 1 yoctoNEAR");

    let swap_action = SwapAction {
      pool_id,
      token_in,
      token_out,
      amount_in: Some(amount_in),
      min_amount_out
    };

    let mut actions = Vec::new();
    actions.push(swap_action);

    let promise = ext_amm_contract::ext(self.amm_contract.clone())
      .with_static_gas(Gas(150*TGAS))
      .with_attached_deposit(YOCTO_NEAR)
      .swap(actions);

    return promise.then( // Create a promise to callback query_greeting_callback
      Self::ext(env::current_account_id())
      .with_static_gas(Gas(100*TGAS))
      .external_call_callback()
    )
  }
}