//! budget program
use bincode::{self, deserialize, serialize_into, serialized_size};
use budget_expr::BudgetExpr;
use budget_instruction::Instruction;
use chrono::prelude::{DateTime, Utc};
use payment_plan::Witness;
use solana_sdk::account::Account;
use solana_sdk::pubkey::Pubkey;
use std::io;
use transaction::Transaction;

#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
pub enum BudgetError {
    InsufficientFunds,
    ContractAlreadyExists,
    ContractNotPending,
    SourceIsPendingContract,
    UninitializedContract,
    NegativeTokens,
    DestinationMissing,
    FailedWitness,
    UserdataTooSmall,
    UserdataDeserializeFailure,
    UnsignedKey,
}

#[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq)]
pub struct BudgetState {
    pub initialized: bool,
    pub pending_budget: Option<BudgetExpr>,
}

const BUDGET_PROGRAM_ID: [u8; 32] = [
    129, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,
];

impl BudgetState {
    fn is_pending(&self) -> bool {
        self.pending_budget != None
    }
    pub fn id() -> Pubkey {
        Pubkey::new(&BUDGET_PROGRAM_ID)
    }
    pub fn check_id(program_id: &Pubkey) -> bool {
        program_id.as_ref() == BUDGET_PROGRAM_ID
    }

    /// Process a Witness Signature. Any payment plans waiting on this signature
    /// will progress one step.
    fn apply_signature(
        &mut self,
        tx: &Transaction,
        instruction_index: usize,
        accounts: &mut [&mut Account],
    ) -> Result<(), BudgetError> {
        let mut final_payment = None;
        if let Some(ref mut expr) = self.pending_budget {
            let key = match tx.signed_key(instruction_index, 0) {
                None => return Err(BudgetError::UnsignedKey),
                Some(key) => key,
            };
            expr.apply_witness(&Witness::Signature, key);
            final_payment = expr.final_payment();
        }

        if let Some(payment) = final_payment {
            if Some(&payment.to) != tx.key(instruction_index, 2) {
                trace!("destination missing");
                return Err(BudgetError::DestinationMissing);
            }
            self.pending_budget = None;
            accounts[1].tokens -= payment.tokens;
            accounts[2].tokens += payment.tokens;
        }
        Ok(())
    }

    /// Process a Witness Timestamp. Any payment plans waiting on this timestamp
    /// will progress one step.
    fn apply_timestamp(
        &mut self,
        tx: &Transaction,
        instruction_index: usize,
        accounts: &mut [&mut Account],
        dt: DateTime<Utc>,
    ) -> Result<(), BudgetError> {
        // Check to see if any timelocked transactions can be completed.
        let mut final_payment = None;

        if let Some(ref mut expr) = self.pending_budget {
            let key = match tx.signed_key(instruction_index, 0) {
                None => return Err(BudgetError::UnsignedKey),
                Some(key) => key,
            };
            expr.apply_witness(&Witness::Timestamp(dt), key);
            final_payment = expr.final_payment();
        }

        if let Some(payment) = final_payment {
            if Some(&payment.to) != tx.key(instruction_index, 2) {
                trace!("destination missing");
                return Err(BudgetError::DestinationMissing);
            }
            self.pending_budget = None;
            accounts[1].tokens -= payment.tokens;
            accounts[2].tokens += payment.tokens;
        }
        Ok(())
    }

    fn apply_debits_to_budget_state(
        tx: &Transaction,
        instruction_index: usize,
        accounts: &mut [&mut Account],
        instruction: &Instruction,
    ) -> Result<(), BudgetError> {
        if !accounts[0].userdata.is_empty() {
            trace!("source is pending");
            return Err(BudgetError::SourceIsPendingContract);
        }
        match instruction {
            Instruction::NewBudget(expr) => {
                let expr = expr.clone();
                if let Some(payment) = expr.final_payment() {
                    accounts[1].tokens += payment.tokens;
                    Ok(())
                } else {
                    let existing = Self::deserialize(&accounts[1].userdata).ok();
                    if Some(true) == existing.map(|x| x.initialized) {
                        trace!("contract already exists");
                        Err(BudgetError::ContractAlreadyExists)
                    } else {
                        let mut state = BudgetState::default();
                        state.pending_budget = Some(expr);
                        accounts[1].tokens += accounts[0].tokens;
                        accounts[0].tokens = 0;
                        state.initialized = true;
                        state.serialize(&mut accounts[1].userdata)
                    }
                }
            }
            Instruction::ApplyTimestamp(dt) => {
                if let Ok(mut state) = Self::deserialize(&accounts[1].userdata) {
                    if !state.is_pending() {
                        Err(BudgetError::ContractNotPending)
                    } else if !state.initialized {
                        trace!("contract is uninitialized");
                        Err(BudgetError::UninitializedContract)
                    } else {
                        trace!("apply timestamp");
                        state.apply_timestamp(tx, instruction_index, accounts, *dt)?;
                        trace!("apply timestamp committed");
                        state.serialize(&mut accounts[1].userdata)
                    }
                } else {
                    Err(BudgetError::UninitializedContract)
                }
            }
            Instruction::ApplySignature => {
                if let Ok(mut state) = Self::deserialize(&accounts[1].userdata) {
                    if !state.is_pending() {
                        Err(BudgetError::ContractNotPending)
                    } else if !state.initialized {
                        trace!("contract is uninitialized");
                        Err(BudgetError::UninitializedContract)
                    } else {
                        trace!("apply signature");
                        state.apply_signature(tx, instruction_index, accounts)?;
                        trace!("apply signature committed");
                        state.serialize(&mut accounts[1].userdata)
                    }
                } else {
                    Err(BudgetError::UninitializedContract)
                }
            }
        }
    }
    fn serialize(&self, output: &mut [u8]) -> Result<(), BudgetError> {
        let len = serialized_size(self).unwrap() as u64;
        if output.len() < len as usize {
            warn!(
                "{} bytes required to serialize, only have {} bytes",
                len,
                output.len()
            );
            return Err(BudgetError::UserdataTooSmall);
        }
        {
            let writer = io::BufWriter::new(&mut output[..8]);
            serialize_into(writer, &len).unwrap();
        }

        {
            let writer = io::BufWriter::new(&mut output[8..8 + len as usize]);
            serialize_into(writer, self).unwrap();
        }
        Ok(())
    }

    pub fn deserialize(input: &[u8]) -> bincode::Result<Self> {
        if input.len() < 8 {
            return Err(Box::new(bincode::ErrorKind::SizeLimit));
        }
        let len: u64 = deserialize(&input[..8]).unwrap();
        if len < 2 {
            return Err(Box::new(bincode::ErrorKind::SizeLimit));
        }
        if input.len() < 8 + len as usize {
            return Err(Box::new(bincode::ErrorKind::SizeLimit));
        }
        deserialize(&input[8..8 + len as usize])
    }

    /// Budget DSL contract interface
    /// * tx - the transaction
    /// * accounts[0] - The source of the tokens
    /// * accounts[1] - The contract context.  Once the contract has been completed, the tokens can
    /// be spent from this account .
    pub fn process_transaction(
        tx: &Transaction,
        instruction_index: usize,
        accounts: &mut [&mut Account],
    ) -> Result<(), BudgetError> {
        if let Ok(instruction) = deserialize(tx.userdata(instruction_index)) {
            trace!("process_transaction: {:?}", instruction);
            Self::apply_debits_to_budget_state(tx, instruction_index, accounts, &instruction)
        } else {
            info!(
                "Invalid transaction userdata: {:?}",
                tx.userdata(instruction_index)
            );
            Err(BudgetError::UserdataDeserializeFailure)
        }
    }

    //TODO the contract needs to provide a "get_balance" introspection call of the userdata
    pub fn get_balance(account: &Account) -> u64 {
        if let Ok(state) = deserialize(&account.userdata) {
            let state: BudgetState = state;
            if state.is_pending() {
                0
            } else {
                account.tokens
            }
        } else {
            account.tokens
        }
    }
}
#[cfg(test)]
mod test {
    use bincode::serialize;
    use budget_program::{BudgetError, BudgetState};
    use budget_transaction::BudgetTransaction;
    use chrono::prelude::{DateTime, NaiveDate, Utc};
    use hash::Hash;
    use signature::{GenKeys, Keypair, KeypairUtil};
    use solana_sdk::account::Account;
    use solana_sdk::pubkey::Pubkey;
    use transaction::Transaction;

    fn process_transaction(tx: &Transaction, accounts: &mut [Account]) -> Result<(), BudgetError> {
        let mut refs: Vec<&mut Account> = accounts.iter_mut().collect();
        BudgetState::process_transaction(&tx, 0, &mut refs[..])
    }
    #[test]
    fn test_serializer() {
        let mut a = Account::new(0, 512, BudgetState::id());
        let b = BudgetState::default();
        b.serialize(&mut a.userdata).unwrap();
        let buf = serialize(&b).unwrap();
        assert_eq!(a.userdata[8..8 + buf.len()], buf[0..]);
        let c = BudgetState::deserialize(&a.userdata).unwrap();
        assert_eq!(b, c);
    }

    #[test]
    fn test_serializer_userdata_too_small() {
        let mut a = Account::new(0, 1, BudgetState::id());
        let b = BudgetState::default();
        assert_eq!(
            b.serialize(&mut a.userdata),
            Err(BudgetError::UserdataTooSmall)
        );
    }
    #[test]
    fn test_invalid_instruction() {
        let mut accounts = vec![
            Account::new(1, 0, BudgetState::id()),
            Account::new(0, 512, BudgetState::id()),
        ];
        let from = Keypair::new();
        let contract = Keypair::new();
        let userdata = (1u8, 2u8, 3u8);
        let tx = Transaction::new(
            &from,
            &[contract.pubkey()],
            BudgetState::id(),
            &userdata,
            Hash::default(),
            0,
        );
        assert!(process_transaction(&tx, &mut accounts).is_err());
    }

    #[test]
    fn test_unsigned_witness_key() {
        let mut accounts = vec![
            Account::new(1, 0, BudgetState::id()),
            Account::new(0, 512, BudgetState::id()),
            Account::new(0, 0, BudgetState::id()),
        ];

        // Initialize BudgetState
        let from = Keypair::new();
        let contract = Keypair::new().pubkey();
        let to = Keypair::new().pubkey();
        let witness = Keypair::new().pubkey();
        let tx = Transaction::budget_new_when_signed(
            &from,
            to,
            contract,
            witness,
            None,
            1,
            Hash::default(),
        );
        process_transaction(&tx, &mut accounts).unwrap();

        // Attack! Part 1: Sign a witness transaction with a random key.
        let rando = Keypair::new();
        let mut tx = Transaction::budget_new_signature(&rando, contract, to, Hash::default());

        // Attack! Part 2: Point the instruction to the expected, but unsigned, key.
        tx.account_keys.push(from.pubkey());
        tx.instructions[0].accounts[0] = 3;

        // Ensure the transaction fails because of the unsigned key.
        assert_eq!(
            process_transaction(&tx, &mut accounts),
            Err(BudgetError::UnsignedKey)
        );
    }

    #[test]
    fn test_unsigned_timestamp() {
        let mut accounts = vec![
            Account::new(1, 0, BudgetState::id()),
            Account::new(0, 512, BudgetState::id()),
            Account::new(0, 0, BudgetState::id()),
        ];

        // Initialize BudgetState
        let from = Keypair::new();
        let contract = Keypair::new().pubkey();
        let to = Keypair::new().pubkey();
        let dt = Utc::now();
        let tx = Transaction::budget_new_on_date(
            &from,
            to,
            contract,
            dt,
            from.pubkey(),
            None,
            1,
            Hash::default(),
        );
        process_transaction(&tx, &mut accounts).unwrap();

        // Attack! Part 1: Sign a timestamp transaction with a random key.
        let rando = Keypair::new();
        let mut tx = Transaction::budget_new_timestamp(&rando, contract, to, dt, Hash::default());

        // Attack! Part 2: Point the instruction to the expected, but unsigned, key.
        tx.account_keys.push(from.pubkey());
        tx.instructions[0].accounts[0] = 3;

        // Ensure the transaction fails because of the unsigned key.
        assert_eq!(
            process_transaction(&tx, &mut accounts),
            Err(BudgetError::UnsignedKey)
        );
    }

    #[test]
    fn test_transfer_on_date() {
        let mut accounts = vec![
            Account::new(1, 0, BudgetState::id()),
            Account::new(0, 512, BudgetState::id()),
            Account::new(0, 0, BudgetState::id()),
        ];
        let from_account = 0;
        let contract_account = 1;
        let to_account = 2;
        let from = Keypair::new();
        let contract = Keypair::new();
        let to = Keypair::new();
        let rando = Keypair::new();
        let dt = Utc::now();
        let tx = Transaction::budget_new_on_date(
            &from,
            to.pubkey(),
            contract.pubkey(),
            dt,
            from.pubkey(),
            None,
            1,
            Hash::default(),
        );
        process_transaction(&tx, &mut accounts).unwrap();
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 1);
        let state = BudgetState::deserialize(&accounts[contract_account].userdata).unwrap();
        assert!(state.is_pending());

        // Attack! Try to payout to a rando key
        let tx = Transaction::budget_new_timestamp(
            &from,
            contract.pubkey(),
            rando.pubkey(),
            dt,
            Hash::default(),
        );
        assert_eq!(
            process_transaction(&tx, &mut accounts),
            Err(BudgetError::DestinationMissing)
        );
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 1);
        assert_eq!(accounts[to_account].tokens, 0);

        let state = BudgetState::deserialize(&accounts[contract_account].userdata).unwrap();
        assert!(state.is_pending());

        // Now, acknowledge the time in the condition occurred and
        // that pubkey's funds are now available.
        let tx = Transaction::budget_new_timestamp(
            &from,
            contract.pubkey(),
            to.pubkey(),
            dt,
            Hash::default(),
        );
        process_transaction(&tx, &mut accounts).unwrap();
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 0);
        assert_eq!(accounts[to_account].tokens, 1);

        let state = BudgetState::deserialize(&accounts[contract_account].userdata).unwrap();
        assert!(!state.is_pending());

        // try to replay the timestamp contract
        assert_eq!(
            process_transaction(&tx, &mut accounts),
            Err(BudgetError::ContractNotPending)
        );
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 0);
        assert_eq!(accounts[to_account].tokens, 1);
    }
    #[test]
    fn test_cancel_transfer() {
        let mut accounts = vec![
            Account::new(1, 0, BudgetState::id()),
            Account::new(0, 512, BudgetState::id()),
            Account::new(0, 0, BudgetState::id()),
        ];
        let from_account = 0;
        let contract_account = 1;
        let pay_account = 2;
        let from = Keypair::new();
        let contract = Keypair::new();
        let to = Keypair::new();
        let dt = Utc::now();
        let tx = Transaction::budget_new_on_date(
            &from,
            to.pubkey(),
            contract.pubkey(),
            dt,
            from.pubkey(),
            Some(from.pubkey()),
            1,
            Hash::default(),
        );
        process_transaction(&tx, &mut accounts).unwrap();
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 1);
        let state = BudgetState::deserialize(&accounts[contract_account].userdata).unwrap();
        assert!(state.is_pending());

        // Attack! try to put the tokens into the wrong account with cancel
        let tx =
            Transaction::budget_new_signature(&to, contract.pubkey(), to.pubkey(), Hash::default());
        // unit test hack, the `from account` is passed instead of the `to` account to avoid
        // creating more account vectors
        process_transaction(&tx, &mut accounts).unwrap();
        // nothing should be changed because apply witness didn't finalize a payment
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 1);
        // this would be the `to.pubkey()` account
        assert_eq!(accounts[pay_account].tokens, 0);

        // Now, cancel the transaction. from gets her funds back
        let tx = Transaction::budget_new_signature(
            &from,
            contract.pubkey(),
            from.pubkey(),
            Hash::default(),
        );
        process_transaction(&tx, &mut accounts).unwrap();
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 0);
        assert_eq!(accounts[pay_account].tokens, 1);

        // try to replay the signature contract
        let tx = Transaction::budget_new_signature(
            &from,
            contract.pubkey(),
            from.pubkey(),
            Hash::default(),
        );
        assert_eq!(
            process_transaction(&tx, &mut accounts),
            Err(BudgetError::ContractNotPending)
        );
        assert_eq!(accounts[from_account].tokens, 0);
        assert_eq!(accounts[contract_account].tokens, 0);
        assert_eq!(accounts[pay_account].tokens, 1);
    }

    #[test]
    fn test_userdata_too_small() {
        let mut accounts = vec![
            Account::new(1, 0, BudgetState::id()),
            Account::new(1, 0, BudgetState::id()), // <== userdata is 0, which is not enough
            Account::new(1, 0, BudgetState::id()),
        ];
        let from = Keypair::new();
        let contract = Keypair::new();
        let to = Keypair::new();
        let tx = Transaction::budget_new_on_date(
            &from,
            to.pubkey(),
            contract.pubkey(),
            Utc::now(),
            from.pubkey(),
            None,
            1,
            Hash::default(),
        );

        assert!(process_transaction(&tx, &mut accounts).is_err());
        assert!(BudgetState::deserialize(&accounts[1].userdata).is_err());

        let tx = Transaction::budget_new_timestamp(
            &from,
            contract.pubkey(),
            to.pubkey(),
            Utc::now(),
            Hash::default(),
        );
        assert!(process_transaction(&tx, &mut accounts).is_err());
        assert!(BudgetState::deserialize(&accounts[1].userdata).is_err());

        // Success if there was no panic...
    }

    /// Detect binary changes in the serialized contract userdata, which could have a downstream
    /// affect on SDKs and DApps
    #[test]
    fn test_sdk_serialize() {
        let keypair = &GenKeys::new([0u8; 32]).gen_n_keypairs(1)[0];
        let to = Pubkey::new(&[
            1, 1, 1, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 8, 7, 6, 5, 4,
            1, 1, 1,
        ]);
        let contract = Pubkey::new(&[
            2, 2, 2, 4, 5, 6, 7, 8, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 8, 7, 6, 5, 4,
            2, 2, 2,
        ]);
        let date =
            DateTime::<Utc>::from_utc(NaiveDate::from_ymd(2016, 7, 8).and_hms(9, 10, 11), Utc);
        let date_iso8601 = "2016-07-08T09:10:11Z";

        let tx = Transaction::budget_new(&keypair, to, 192, Hash::default());
        assert_eq!(
            tx.userdata(0).to_vec(),
            vec![2, 0, 0, 0, 192, 0, 0, 0, 0, 0, 0, 0]
        );
        assert_eq!(
            tx.userdata(1).to_vec(),
            vec![
                0, 0, 0, 0, 0, 0, 0, 0, 192, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 4, 5, 6, 7, 8, 9, 0, 0,
                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 8, 7, 6, 5, 4, 1, 1, 1
            ]
        );

        let tx = Transaction::budget_new_on_date(
            &keypair,
            to,
            contract,
            date,
            keypair.pubkey(),
            Some(keypair.pubkey()),
            192,
            Hash::default(),
        );
        assert_eq!(
            tx.userdata(0).to_vec(),
            vec![
                0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 20, 0, 0, 0, 0, 0, 0, 0, 50, 48, 49, 54, 45,
                48, 55, 45, 48, 56, 84, 48, 57, 58, 49, 48, 58, 49, 49, 90, 32, 253, 186, 201, 177,
                11, 117, 135, 187, 167, 181, 188, 22, 59, 206, 105, 231, 150, 215, 30, 78, 212, 76,
                16, 252, 180, 72, 134, 137, 247, 161, 68, 192, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 4, 5,
                6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 8, 7, 6, 5, 4, 1, 1, 1, 1,
                0, 0, 0, 32, 253, 186, 201, 177, 11, 117, 135, 187, 167, 181, 188, 22, 59, 206,
                105, 231, 150, 215, 30, 78, 212, 76, 16, 252, 180, 72, 134, 137, 247, 161, 68, 192,
                0, 0, 0, 0, 0, 0, 0, 32, 253, 186, 201, 177, 11, 117, 135, 187, 167, 181, 188, 22,
                59, 206, 105, 231, 150, 215, 30, 78, 212, 76, 16, 252, 180, 72, 134, 137, 247, 161,
                68
            ]
        );

        // ApplyTimestamp(date)
        let tx = Transaction::budget_new_timestamp(
            &keypair,
            keypair.pubkey(),
            to,
            date,
            Hash::default(),
        );
        let mut expected_userdata = vec![1, 0, 0, 0, 20, 0, 0, 0, 0, 0, 0, 0];
        expected_userdata.extend(date_iso8601.as_bytes());
        assert_eq!(tx.userdata(0).to_vec(), expected_userdata);

        // ApplySignature
        let tx = Transaction::budget_new_signature(&keypair, keypair.pubkey(), to, Hash::default());
        assert_eq!(tx.userdata(0).to_vec(), vec![2, 0, 0, 0]);
    }
}