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use account::Account;
use memo::Memo;
use operation::Operation;
use transaction::{Transaction, Fee};
use time_bounds::{TimeBounds, UnixTimestamp};
use error::Result;

const BASE_FEE: u32 = 100;

pub struct TransactionBuilder<'a> {
    source: &'a mut Account,
    base_fee: Fee,
    memo: Memo,
    lower_time_bound: Option<UnixTimestamp>,
    upper_time_bound: Option<UnixTimestamp>,
    operations: Vec<Operation>,
}

impl<'a> TransactionBuilder<'a> {
    pub fn new(source: &'a mut Account) -> TransactionBuilder<'a> {
        TransactionBuilder {
            source: source,
            base_fee: BASE_FEE,
            memo: Memo::None,
            lower_time_bound: None,
            upper_time_bound: None,
            operations: Vec::new(),
        }
    }

    pub fn add_operation(mut self, op: Operation) -> TransactionBuilder<'a> {
        self.operations.push(op);
        self
    }

    pub fn with_memo(mut self, memo: Memo) -> TransactionBuilder<'a> {
        self.memo = memo;
        self
    }

    pub fn with_fee(mut self, fee: Fee) -> TransactionBuilder<'a> {
        self.base_fee = fee;
        self
    }

    pub fn with_lower_time_bound(mut self, t: UnixTimestamp) -> TransactionBuilder<'a> {
        self.lower_time_bound = Some(t);
        self
    }

    pub fn with_upper_time_bound(mut self, t: UnixTimestamp) -> TransactionBuilder<'a> {
        self.upper_time_bound = Some(t);
        self
    }

    pub fn build(self) -> Result<Transaction> {
        let seqnum = self.source.seqnum() + 1;
        let time_bounds = match (self.lower_time_bound, self.upper_time_bound) {
            (None, None) => None,
            (l, u) => Some(TimeBounds::new(l, u)),
        };
        let public_key = self.source.public_key().clone();
        let fee = self.base_fee * (self.operations.len() as u32);
        let tx = Transaction::new(public_key,
                                  fee,
                                  self.memo,
                                  seqnum,
                                  time_bounds,
                                  self.operations);
        self.source.inc_seqnum();
        Ok(tx)
    }
}

#[cfg(test)]
mod tests {
    use TransactionBuilder;
    use account::Account;

    #[test]
    fn increment_account_seqnum_on_build() {
        let mut account =
            Account::from_account_id("GBBM6BKZPEHWYO3E3YKREDPQXMS4VK35YLNU7NFBRI26RAN7GI5POFBB",
                                     100)
                .unwrap();
        let _tx = TransactionBuilder::new(&mut account).build();
        assert_eq!(account.seqnum(), 101);
    }
}