//! Instruction types

#![allow(clippy::too_many_arguments)]

use crate::error::SwapError;
use crate::fees::Fees;
use solana_program::{
    instruction::{AccountMeta, Instruction},
    program_error::ProgramError,
    program_pack::Pack,
    pubkey::Pubkey,
};
use std::mem::size_of;

/// Initialize instruction data
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub struct InitializeData {
    /// Nonce used to create valid program address
    pub nonce: u8,
    /// Amplification coefficient (A)
    pub amp_factor: u64,
    /// Fees
    pub fees: Fees,
}

/// Swap instruction data
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub struct SwapData {
    /// SOURCE amount to transfer, output to DESTINATION is based on the exchange rate
    pub amount_in: u64,
    /// Minimum amount of DESTINATION token to output, prevents excessive slippage
    pub minimum_amount_out: u64,
}

/// Deposit instruction data
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub struct DepositData {
    /// Token A amount to deposit
    pub token_a_amount: u64,
    /// Token B amount to deposit
    pub token_b_amount: u64,
    /// Minimum LP tokens to mint, prevents excessive slippage
    pub min_mint_amount: u64,
}

/// Withdraw instruction data
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub struct WithdrawData {
    /// Amount of pool tokens to burn. User receives an output of token a
    /// and b based on the percentage of the pool tokens that are returned.
    pub pool_token_amount: u64,
    /// Minimum amount of token A to receive, prevents excessive slippage
    pub minimum_token_a_amount: u64,
    /// Minimum amount of token B to receive, prevents excessive slippage
    pub minimum_token_b_amount: u64,
}

/// Withdraw instruction data
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub struct WithdrawOneData {
    /// Amount of pool tokens to burn. User receives an output of token a
    /// or b based on the percentage of the pool tokens that are returned.
    pub pool_token_amount: u64,
    /// Minimum amount of token A or B to receive, prevents excessive slippage
    pub minimum_token_amount: u64,
}

/// RampA instruction data
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub struct RampAData {
    /// Amp. Coefficient to ramp to
    pub target_amp: u64,
    /// Unix timestamp to stop ramp
    pub stop_ramp_ts: i64,
}

/// Admin only instructions.
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum AdminInstruction {
    /// Starts a ramp of A to the next value.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    RampA(RampAData),

    /// Cancels the pending ramp of A.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    StopRampA,

    /// Pauses swap, deposit, and withdraw_one.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    Pause,

    /// Unpauses the swap.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    Unpause,

    /// Sets the account that receives admin fees.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    /// 2. `[]` Token account to receive fees. Must have mint of Token A or Token B.
    SetFeeAccount,

    /// Finalizes the admin transfer. This is run after CommitNewAdmin.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    ApplyNewAdmin,

    /// Commits a new admin. The admin must accept ownership within 3 days.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    /// 2. `[]` New admin account
    CommitNewAdmin,

    /// Updates the swap fees.
    ///
    /// 0. `[writable]` StableSwap
    /// 1. `[signer]` Admin account
    SetNewFees(Fees),
}

impl AdminInstruction {
    /// Unpacks a byte buffer into a [AdminInstruction](enum.AdminInstruction.html).
    pub fn unpack(input: &[u8]) -> Result<Option<Self>, ProgramError> {
        let (&tag, rest) = input.split_first().ok_or(SwapError::InvalidInstruction)?;
        Ok(match tag {
            100 => {
                let (target_amp, rest) = unpack_u64(rest)?;
                let (stop_ramp_ts, _rest) = unpack_i64(rest)?;
                Some(Self::RampA(RampAData {
                    target_amp,
                    stop_ramp_ts,
                }))
            }
            101 => Some(Self::StopRampA),
            102 => Some(Self::Pause),
            103 => Some(Self::Unpause),
            104 => Some(Self::SetFeeAccount),
            105 => Some(Self::ApplyNewAdmin),
            106 => Some(Self::CommitNewAdmin),
            107 => {
                let fees = Fees::unpack_unchecked(rest)?;
                Some(Self::SetNewFees(fees))
            }
            _ => None,
        })
    }

    /// Packs a [AdminInstruction](enum.AdminInstruction.html) into a byte buffer.
    pub fn pack(&self) -> Vec<u8> {
        let mut buf = Vec::with_capacity(size_of::<Self>());
        match *self {
            Self::RampA(RampAData {
                target_amp,
                stop_ramp_ts,
            }) => {
                buf.push(100);
                buf.extend_from_slice(&target_amp.to_le_bytes());
                buf.extend_from_slice(&stop_ramp_ts.to_le_bytes());
            }
            Self::StopRampA => buf.push(101),
            Self::Pause => buf.push(102),
            Self::Unpause => buf.push(103),
            Self::SetFeeAccount => buf.push(104),
            Self::ApplyNewAdmin => buf.push(105),
            Self::CommitNewAdmin => buf.push(106),
            Self::SetNewFees(fees) => {
                buf.push(107);
                let mut fees_slice = [0u8; Fees::LEN];
                Pack::pack_into_slice(&fees, &mut fees_slice[..]);
                buf.extend_from_slice(&fees_slice);
            }
        }
        buf
    }
}

/// Creates a 'ramp_a' instruction
pub fn ramp_a(
    swap_pubkey: &Pubkey,
    admin_pubkey: &Pubkey,
    target_amp: u64,
    stop_ramp_ts: i64,
) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::RampA(RampAData {
        target_amp,
        stop_ramp_ts,
    })
    .pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'stop_ramp_a' instruction
pub fn stop_ramp_a(
    swap_pubkey: &Pubkey,
    admin_pubkey: &Pubkey,
) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::StopRampA.pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'pause' instruction
pub fn pause(swap_pubkey: &Pubkey, admin_pubkey: &Pubkey) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::Pause.pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'unpause' instruction
pub fn unpause(swap_pubkey: &Pubkey, admin_pubkey: &Pubkey) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::Unpause.pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'apply_new_admin' instruction
pub fn apply_new_admin(
    swap_pubkey: &Pubkey,
    admin_pubkey: &Pubkey,
) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::ApplyNewAdmin.pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'commit_new_admin' instruction
pub fn commit_new_admin(
    swap_pubkey: &Pubkey,
    admin_pubkey: &Pubkey,
    new_admin_pubkey: &Pubkey,
) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::CommitNewAdmin.pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
        AccountMeta::new_readonly(*new_admin_pubkey, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'set_fee_account' instruction
pub fn set_fee_account(
    swap_pubkey: &Pubkey,
    admin_pubkey: &Pubkey,
    new_fee_account_pubkey: &Pubkey,
) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::SetFeeAccount.pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
        AccountMeta::new_readonly(*new_fee_account_pubkey, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'set_new_fees' instruction
pub fn set_new_fees(
    swap_pubkey: &Pubkey,
    admin_pubkey: &Pubkey,
    new_fees: Fees,
) -> Result<Instruction, ProgramError> {
    let data = AdminInstruction::SetNewFees(new_fees).pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, false),
        AccountMeta::new_readonly(*admin_pubkey, true),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Instructions supported by the SwapInfo program.
#[repr(C)]
#[derive(Copy, Clone, Debug, PartialEq)]
#[cfg_attr(feature = "fuzz", derive(arbitrary::Arbitrary))]
pub enum SwapInstruction {
    /// Initializes a new SwapInfo.
    ///
    /// 0. `[writable, signer]` New StableSwap to create.
    /// 1. `[]` $authority derived from `create_program_address(&[StableSwap account])`
    /// 2. `[]` admin Account.
    /// 3. `[]` admin_fee_a admin fee Account for token_a.
    /// 4. `[]` admin_fee_b admin fee Account for token_b.
    /// 5. `[]` token_a Account. Must be non zero, owned by $authority.
    /// 6. `[]` token_b Account. Must be non zero, owned by $authority.
    /// 7. `[writable]` Pool Token Mint. Must be empty, owned by $authority.
    Initialize(InitializeData),

    /// Swap the tokens in the pool.
    ///
    /// 0. `[]`StableSwap
    /// 1. `[]` $authority
    /// 2. `[signer]` User authority.
    /// 3. `[writable]` token_(A|B) SOURCE Account, amount is transferable by $authority,
    /// 4. `[writable]` token_(A|B) Base Account to swap INTO.  Must be the SOURCE token.
    /// 5. `[writable]` token_(A|B) Base Account to swap FROM.  Must be the DESTINATION token.
    /// 6. `[writable]` token_(A|B) DESTINATION Account assigned to USER as the owner.
    /// 7. `[writable]` token_(A|B) admin fee Account. Must have same mint as DESTINATION token.
    /// 8. `[]` Token program id
    Swap(SwapData),

    /// Deposit some tokens into the pool.  The output is a "pool" token representing ownership
    /// into the pool. Inputs are converted to the current ratio.
    ///
    /// 0. `[]`StableSwap
    /// 1. `[]` $authority
    /// 2. `[signer]` User authority.
    /// 3. `[writable]` token_a $authority can transfer amount,
    /// 4. `[writable]` token_b $authority can transfer amount,
    /// 5. `[writable]` token_a Base Account to deposit into.
    /// 6. `[writable]` token_b Base Account to deposit into.
    /// 7. `[writable]` Pool MINT account, $authority is the owner.
    /// 8. `[writable]` Pool Account to deposit the generated tokens, user is the owner.
    /// 9. `[]` Token program id
    Deposit(DepositData),

    /// Withdraw tokens from the pool at the current ratio.
    ///
    /// 0. `[]`StableSwap
    /// 1. `[]` $authority
    /// 2. `[signer]` User authority.
    /// 3. `[writable]` Pool mint account, $authority is the owner
    /// 4. `[writable]` SOURCE Pool account, amount is transferable by $authority.
    /// 5. `[writable]` token_a Swap Account to withdraw FROM.
    /// 6. `[writable]` token_b Swap Account to withdraw FROM.
    /// 7. `[writable]` token_a user Account to credit.
    /// 8. `[writable]` token_b user Account to credit.
    /// 9. `[writable]` admin_fee_a admin fee Account for token_a.
    /// 10. `[writable]` admin_fee_b admin fee Account for token_b.
    /// 11. `[]` Token program id
    Withdraw(WithdrawData),

    /// Withdraw one token from the pool at the current ratio.
    ///
    /// 0. `[]`StableSwap
    /// 1. `[]` $authority
    /// 2. `[signer]` User authority.
    /// 3. `[writable]` Pool mint account, $authority is the owner
    /// 4. `[writable]` SOURCE Pool account, amount is transferable by $authority.
    /// 5. `[writable]` token_(A|B) BASE token Swap Account to withdraw FROM.
    /// 6. `[writable]` token_(A|B) QUOTE token Swap Account to exchange to base token.
    /// 7. `[writable]` token_(A|B) BASE token user Account to credit.
    /// 8. `[writable]` token_(A|B) admin fee Account. Must have same mint as BASE token.
    /// 9. `[]` Token program id
    WithdrawOne(WithdrawOneData),
}

impl SwapInstruction {
    /// Unpacks a byte buffer into a [SwapInstruction](enum.SwapInstruction.html).
    pub fn unpack(input: &[u8]) -> Result<Self, ProgramError> {
        let (&tag, rest) = input.split_first().ok_or(SwapError::InvalidInstruction)?;
        Ok(match tag {
            0 => {
                let (&nonce, rest) = rest.split_first().ok_or(SwapError::InvalidInstruction)?;
                let (amp_factor, rest) = unpack_u64(rest)?;
                let fees = Fees::unpack_unchecked(rest)?;
                Self::Initialize(InitializeData {
                    nonce,
                    amp_factor,
                    fees,
                })
            }
            1 => {
                let (amount_in, rest) = unpack_u64(rest)?;
                let (minimum_amount_out, _rest) = unpack_u64(rest)?;
                Self::Swap(SwapData {
                    amount_in,
                    minimum_amount_out,
                })
            }
            2 => {
                let (token_a_amount, rest) = unpack_u64(rest)?;
                let (token_b_amount, rest) = unpack_u64(rest)?;
                let (min_mint_amount, _rest) = unpack_u64(rest)?;
                Self::Deposit(DepositData {
                    token_a_amount,
                    token_b_amount,
                    min_mint_amount,
                })
            }
            3 => {
                let (pool_token_amount, rest) = unpack_u64(rest)?;
                let (minimum_token_a_amount, rest) = unpack_u64(rest)?;
                let (minimum_token_b_amount, _rest) = unpack_u64(rest)?;
                Self::Withdraw(WithdrawData {
                    pool_token_amount,
                    minimum_token_a_amount,
                    minimum_token_b_amount,
                })
            }
            4 => {
                let (pool_token_amount, rest) = unpack_u64(rest)?;
                let (minimum_token_amount, _rest) = unpack_u64(rest)?;
                Self::WithdrawOne(WithdrawOneData {
                    pool_token_amount,
                    minimum_token_amount,
                })
            }
            _ => return Err(SwapError::InvalidInstruction.into()),
        })
    }

    /// Packs a [SwapInstruction](enum.SwapInstruction.html) into a byte buffer.
    pub fn pack(&self) -> Vec<u8> {
        let mut buf = Vec::with_capacity(size_of::<Self>());
        match *self {
            Self::Initialize(InitializeData {
                nonce,
                amp_factor,
                fees,
            }) => {
                buf.push(0);
                buf.push(nonce);
                buf.extend_from_slice(&amp_factor.to_le_bytes());
                let mut fees_slice = [0u8; Fees::LEN];
                Pack::pack_into_slice(&fees, &mut fees_slice[..]);
                buf.extend_from_slice(&fees_slice);
            }
            Self::Swap(SwapData {
                amount_in,
                minimum_amount_out,
            }) => {
                buf.push(1);
                buf.extend_from_slice(&amount_in.to_le_bytes());
                buf.extend_from_slice(&minimum_amount_out.to_le_bytes());
            }
            Self::Deposit(DepositData {
                token_a_amount,
                token_b_amount,
                min_mint_amount,
            }) => {
                buf.push(2);
                buf.extend_from_slice(&token_a_amount.to_le_bytes());
                buf.extend_from_slice(&token_b_amount.to_le_bytes());
                buf.extend_from_slice(&min_mint_amount.to_le_bytes());
            }
            Self::Withdraw(WithdrawData {
                pool_token_amount,
                minimum_token_a_amount,
                minimum_token_b_amount,
            }) => {
                buf.push(3);
                buf.extend_from_slice(&pool_token_amount.to_le_bytes());
                buf.extend_from_slice(&minimum_token_a_amount.to_le_bytes());
                buf.extend_from_slice(&minimum_token_b_amount.to_le_bytes());
            }
            Self::WithdrawOne(WithdrawOneData {
                pool_token_amount,
                minimum_token_amount,
            }) => {
                buf.push(4);
                buf.extend_from_slice(&pool_token_amount.to_le_bytes());
                buf.extend_from_slice(&minimum_token_amount.to_le_bytes());
            }
        }
        buf
    }
}

/// Creates an 'initialize' instruction.
pub fn initialize(
    pool_token_program_id: &Pubkey, // Token program used for the pool token
    swap_pubkey: &Pubkey,
    swap_authority_key: &Pubkey,
    admin_pubkey: &Pubkey,
    admin_fee_a_pubkey: &Pubkey,
    admin_fee_b_pubkey: &Pubkey,
    token_a_mint_pubkey: &Pubkey,
    token_a_pubkey: &Pubkey,
    token_b_mint_pubkey: &Pubkey,
    token_b_pubkey: &Pubkey,
    pool_mint_pubkey: &Pubkey,
    destination_pubkey: &Pubkey, // Destination to mint pool tokens for bootstrapper
    nonce: u8,
    amp_factor: u64,
    fees: Fees,
) -> Result<Instruction, ProgramError> {
    let data = SwapInstruction::Initialize(InitializeData {
        nonce,
        amp_factor,
        fees,
    })
    .pack();

    let accounts = vec![
        AccountMeta::new(*swap_pubkey, true),
        AccountMeta::new_readonly(*swap_authority_key, false),
        AccountMeta::new_readonly(*admin_pubkey, false),
        AccountMeta::new_readonly(*admin_fee_a_pubkey, false),
        AccountMeta::new_readonly(*admin_fee_b_pubkey, false),
        AccountMeta::new_readonly(*token_a_mint_pubkey, false),
        AccountMeta::new_readonly(*token_a_pubkey, false),
        AccountMeta::new_readonly(*token_b_mint_pubkey, false),
        AccountMeta::new_readonly(*token_b_pubkey, false),
        AccountMeta::new(*pool_mint_pubkey, false),
        AccountMeta::new(*destination_pubkey, false),
        AccountMeta::new_readonly(*pool_token_program_id, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'deposit' instruction.
#[inline(always)]
pub fn deposit(
    token_program_id: &Pubkey,
    swap_pubkey: &Pubkey,
    swap_authority_key: &Pubkey,
    user_authority_key: &Pubkey,
    deposit_token_a_pubkey: &Pubkey,
    deposit_token_b_pubkey: &Pubkey,
    swap_token_a_pubkey: &Pubkey,
    swap_token_b_pubkey: &Pubkey,
    pool_mint_pubkey: &Pubkey,
    destination_pubkey: &Pubkey,
    token_a_amount: u64,
    token_b_amount: u64,
    min_mint_amount: u64,
) -> Result<Instruction, ProgramError> {
    let data = SwapInstruction::Deposit(DepositData {
        token_a_amount,
        token_b_amount,
        min_mint_amount,
    })
    .pack();

    let accounts = vec![
        AccountMeta::new_readonly(*swap_pubkey, false),
        AccountMeta::new_readonly(*swap_authority_key, false),
        AccountMeta::new_readonly(*user_authority_key, true),
        AccountMeta::new(*deposit_token_a_pubkey, false),
        AccountMeta::new(*deposit_token_b_pubkey, false),
        AccountMeta::new(*swap_token_a_pubkey, false),
        AccountMeta::new(*swap_token_b_pubkey, false),
        AccountMeta::new(*pool_mint_pubkey, false),
        AccountMeta::new(*destination_pubkey, false),
        AccountMeta::new_readonly(*token_program_id, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'withdraw' instruction.
#[inline(always)]
pub fn withdraw(
    token_program_id: &Pubkey,
    swap_pubkey: &Pubkey,
    swap_authority_key: &Pubkey,
    user_authority_key: &Pubkey,
    pool_mint_pubkey: &Pubkey,
    source_pubkey: &Pubkey,
    swap_token_a_pubkey: &Pubkey,
    swap_token_b_pubkey: &Pubkey,
    destination_token_a_pubkey: &Pubkey,
    destination_token_b_pubkey: &Pubkey,
    admin_fee_a_pubkey: &Pubkey,
    admin_fee_b_pubkey: &Pubkey,
    pool_token_amount: u64,
    minimum_token_a_amount: u64,
    minimum_token_b_amount: u64,
) -> Result<Instruction, ProgramError> {
    let data = SwapInstruction::Withdraw(WithdrawData {
        pool_token_amount,
        minimum_token_a_amount,
        minimum_token_b_amount,
    })
    .pack();

    let accounts = vec![
        AccountMeta::new_readonly(*swap_pubkey, false),
        AccountMeta::new_readonly(*swap_authority_key, false),
        AccountMeta::new_readonly(*user_authority_key, true),
        AccountMeta::new(*pool_mint_pubkey, false),
        AccountMeta::new(*source_pubkey, false),
        AccountMeta::new(*swap_token_a_pubkey, false),
        AccountMeta::new(*swap_token_b_pubkey, false),
        AccountMeta::new(*destination_token_a_pubkey, false),
        AccountMeta::new(*destination_token_b_pubkey, false),
        AccountMeta::new(*admin_fee_a_pubkey, false),
        AccountMeta::new(*admin_fee_b_pubkey, false),
        AccountMeta::new_readonly(*token_program_id, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'swap' instruction.
#[inline(always)]
pub fn swap(
    token_program_id: &Pubkey,
    swap_pubkey: &Pubkey,
    swap_authority_key: &Pubkey,
    user_authority_key: &Pubkey,
    source_pubkey: &Pubkey,
    swap_source_pubkey: &Pubkey,
    swap_destination_pubkey: &Pubkey,
    destination_pubkey: &Pubkey,
    admin_fee_destination_pubkey: &Pubkey,
    amount_in: u64,
    minimum_amount_out: u64,
) -> Result<Instruction, ProgramError> {
    let data = SwapInstruction::Swap(SwapData {
        amount_in,
        minimum_amount_out,
    })
    .pack();

    let accounts = vec![
        AccountMeta::new_readonly(*swap_pubkey, false),
        AccountMeta::new_readonly(*swap_authority_key, false),
        AccountMeta::new_readonly(*user_authority_key, true),
        AccountMeta::new(*source_pubkey, false),
        AccountMeta::new(*swap_source_pubkey, false),
        AccountMeta::new(*swap_destination_pubkey, false),
        AccountMeta::new(*destination_pubkey, false),
        AccountMeta::new(*admin_fee_destination_pubkey, false),
        AccountMeta::new_readonly(*token_program_id, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

/// Creates a 'withdraw_one' instruction.
#[inline(always)]
pub fn withdraw_one(
    token_program_id: &Pubkey,
    swap_pubkey: &Pubkey,
    swap_authority_key: &Pubkey,
    user_authority_key: &Pubkey,
    pool_mint_pubkey: &Pubkey,
    source_pubkey: &Pubkey,
    swap_base_token_pubkey: &Pubkey,
    swap_quote_token_pubkey: &Pubkey,
    base_destination_pubkey: &Pubkey,
    admin_fee_destination_pubkey: &Pubkey,
    pool_token_amount: u64,
    minimum_token_amount: u64,
) -> Result<Instruction, ProgramError> {
    let data = SwapInstruction::WithdrawOne(WithdrawOneData {
        pool_token_amount,
        minimum_token_amount,
    })
    .pack();

    let accounts = vec![
        AccountMeta::new_readonly(*swap_pubkey, false),
        AccountMeta::new_readonly(*swap_authority_key, false),
        AccountMeta::new_readonly(*user_authority_key, true),
        AccountMeta::new(*pool_mint_pubkey, false),
        AccountMeta::new(*source_pubkey, false),
        AccountMeta::new(*swap_base_token_pubkey, false),
        AccountMeta::new(*swap_quote_token_pubkey, false),
        AccountMeta::new(*base_destination_pubkey, false),
        AccountMeta::new(*admin_fee_destination_pubkey, false),
        AccountMeta::new_readonly(*token_program_id, false),
    ];

    Ok(Instruction {
        program_id: crate::ID,
        accounts,
        data,
    })
}

fn unpack_i64(input: &[u8]) -> Result<(i64, &[u8]), ProgramError> {
    if input.len() >= 8 {
        let (amount, rest) = input.split_at(8);
        let amount = amount
            .get(..8)
            .and_then(|slice| slice.try_into().ok())
            .map(i64::from_le_bytes)
            .ok_or(SwapError::InvalidInstruction)?;
        Ok((amount, rest))
    } else {
        Err(SwapError::InvalidInstruction.into())
    }
}

fn unpack_u64(input: &[u8]) -> Result<(u64, &[u8]), ProgramError> {
    if input.len() >= 8 {
        let (amount, rest) = input.split_at(8);
        let amount = amount
            .get(..8)
            .and_then(|slice| slice.try_into().ok())
            .map(u64::from_le_bytes)
            .ok_or(SwapError::InvalidInstruction)?;
        Ok((amount, rest))
    } else {
        Err(SwapError::InvalidInstruction.into())
    }
}

#[cfg(test)]
#[allow(clippy::unwrap_used)]
mod tests {
    use super::*;

    #[test]
    fn test_admin_instruction_packing() {
        let target_amp = 100;
        let stop_ramp_ts = i64::MAX;
        let check = AdminInstruction::RampA(RampAData {
            target_amp,
            stop_ramp_ts,
        });
        let packed = check.pack();
        let mut expect = vec![100_u8];
        expect.extend_from_slice(&target_amp.to_le_bytes());
        expect.extend_from_slice(&stop_ramp_ts.to_le_bytes());
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let check = AdminInstruction::StopRampA;
        let packed = check.pack();
        let expect = vec![101_u8];
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let check = AdminInstruction::Pause;
        let packed = check.pack();
        let expect = vec![102_u8];
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let check = AdminInstruction::Unpause;
        let packed = check.pack();
        let expect = vec![103_u8];
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let check = AdminInstruction::SetFeeAccount;
        let packed = check.pack();
        let expect = vec![104_u8];
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let check = AdminInstruction::ApplyNewAdmin;
        let packed = check.pack();
        let expect = vec![105_u8];
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let check = AdminInstruction::CommitNewAdmin;
        let packed = check.pack();
        let expect = vec![106_u8];
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));

        let new_fees = Fees {
            admin_trade_fee_numerator: 1,
            admin_trade_fee_denominator: 2,
            admin_withdraw_fee_numerator: 3,
            admin_withdraw_fee_denominator: 4,
            trade_fee_numerator: 5,
            trade_fee_denominator: 6,
            withdraw_fee_numerator: 7,
            withdraw_fee_denominator: 8,
        };
        let check = AdminInstruction::SetNewFees(new_fees);
        let packed = check.pack();
        let mut expect = vec![107_u8];
        let mut new_fees_slice = [0u8; Fees::LEN];
        new_fees.pack_into_slice(&mut new_fees_slice[..]);
        expect.extend_from_slice(&new_fees_slice);
        assert_eq!(packed, expect);
        let unpacked = AdminInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, Some(check));
    }

    #[test]
    fn test_swap_instruction_packing() {
        let nonce: u8 = 255;
        let amp_factor: u64 = 0;
        let fees = Fees {
            admin_trade_fee_numerator: 1,
            admin_trade_fee_denominator: 2,
            admin_withdraw_fee_numerator: 3,
            admin_withdraw_fee_denominator: 4,
            trade_fee_numerator: 5,
            trade_fee_denominator: 6,
            withdraw_fee_numerator: 7,
            withdraw_fee_denominator: 8,
        };
        let check = SwapInstruction::Initialize(InitializeData {
            nonce,
            amp_factor,
            fees,
        });
        let packed = check.pack();
        let mut expect = vec![0_u8, nonce];
        expect.extend_from_slice(&amp_factor.to_le_bytes());
        let mut fees_slice = [0u8; Fees::LEN];
        fees.pack_into_slice(&mut fees_slice[..]);
        expect.extend_from_slice(&fees_slice);
        assert_eq!(packed, expect);
        let unpacked = SwapInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, check);

        let amount_in: u64 = 2;
        let minimum_amount_out: u64 = 10;
        let check = SwapInstruction::Swap(SwapData {
            amount_in,
            minimum_amount_out,
        });
        let packed = check.pack();
        let mut expect = vec![1];
        expect.extend_from_slice(&amount_in.to_le_bytes());
        expect.extend_from_slice(&minimum_amount_out.to_le_bytes());
        assert_eq!(packed, expect);
        let unpacked = SwapInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, check);

        let token_a_amount: u64 = 10;
        let token_b_amount: u64 = 20;
        let min_mint_amount: u64 = 5;
        let check = SwapInstruction::Deposit(DepositData {
            token_a_amount,
            token_b_amount,
            min_mint_amount,
        });
        let packed = check.pack();
        let mut expect = vec![2];
        expect.extend_from_slice(&token_a_amount.to_le_bytes());
        expect.extend_from_slice(&token_b_amount.to_le_bytes());
        expect.extend_from_slice(&min_mint_amount.to_le_bytes());
        assert_eq!(packed, expect);
        let unpacked = SwapInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, check);

        let pool_token_amount: u64 = 1212438012089;
        let minimum_token_a_amount: u64 = 102198761982612;
        let minimum_token_b_amount: u64 = 2011239855213;
        let check = SwapInstruction::Withdraw(WithdrawData {
            pool_token_amount,
            minimum_token_a_amount,
            minimum_token_b_amount,
        });
        let packed = check.pack();
        let mut expect = vec![3];
        expect.extend_from_slice(&pool_token_amount.to_le_bytes());
        expect.extend_from_slice(&minimum_token_a_amount.to_le_bytes());
        expect.extend_from_slice(&minimum_token_b_amount.to_le_bytes());
        assert_eq!(packed, expect);
        let unpacked = SwapInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, check);

        let pool_token_amount: u64 = 1212438012089;
        let minimum_token_amount: u64 = 102198761982612;
        let check = SwapInstruction::WithdrawOne(WithdrawOneData {
            pool_token_amount,
            minimum_token_amount,
        });
        let packed = check.pack();
        let mut expect = vec![4];
        expect.extend_from_slice(&pool_token_amount.to_le_bytes());
        expect.extend_from_slice(&minimum_token_amount.to_le_bytes());
        assert_eq!(packed, expect);
        let unpacked = SwapInstruction::unpack(&expect).unwrap();
        assert_eq!(unpacked, check);
    }
}