//! @brief An Upgradeable Solana BPF loader.
//!
//! The upgradeable BPF loader is responsible for deploying, upgrading, and
//! executing BPF programs.  The upgradeable loader allows a program's authority
//! to update the program at any time.  This ability break's the "code is law"
//! contract the usually enforces the policy that once a program is on-chain it
//! becomes immutable.  Because of this, care should be taken before executing
//! upgradeable programs which still have a functioning authority.  For more
//! information refer to `loader_upgradeable_instruction.rs`

use crate::{
    instruction::{AccountMeta, Instruction, InstructionError},
    loader_upgradeable_instruction::UpgradeableLoaderInstruction,
    pubkey::Pubkey,
    system_instruction, sysvar,
};
use bincode::serialized_size;

crate::declare_id!("BPFLoaderUpgradeab1e11111111111111111111111");

/// Upgradeable loader account states
#[derive(Debug, Serialize, Deserialize, PartialEq, Clone, Copy, AbiExample)]
pub enum UpgradeableLoaderState {
    /// Account is not initialized.
    Uninitialized,
    /// A Buffer account.
    Buffer {
        /// Authority address
        authority_address: Option<Pubkey>,
        // The raw program data follows this serialized structure in the
        // account's data.
    },
    /// An Program account.
    Program {
        /// Address of the ProgramData account.
        programdata_address: Pubkey,
    },
    // A ProgramData account.
    ProgramData {
        /// Slot that the program was last modified.
        slot: u64,
        /// Address of the Program's upgrade authority.
        upgrade_authority_address: Option<Pubkey>,
        // The raw program data follows this serialized structure in the
        // account's data.
    },
}
impl UpgradeableLoaderState {
    /// Length of an buffer account's data.
    pub fn buffer_len(program_len: usize) -> Result<usize, InstructionError> {
        Ok(serialized_size(&Self::Buffer {
            authority_address: Some(Pubkey::default()),
        })
        .map(|len| len as usize)
        .map_err(|_| InstructionError::InvalidInstructionData)?
        .saturating_add(program_len))
    }
    /// Offset into the ProgramData account's data of the program bits.
    pub fn buffer_data_offset() -> Result<usize, InstructionError> {
        Self::buffer_len(0)
    }
    /// Length of an executable account's data.
    pub fn program_len() -> Result<usize, InstructionError> {
        serialized_size(&Self::Program {
            programdata_address: Pubkey::default(),
        })
        .map(|len| len as usize)
        .map_err(|_| InstructionError::InvalidInstructionData)
    }
    /// Length of a ProgramData account's data.
    pub fn programdata_len(program_len: usize) -> Result<usize, InstructionError> {
        Ok(serialized_size(&Self::ProgramData {
            slot: 0,
            upgrade_authority_address: Some(Pubkey::default()),
        })
        .map(|len| len as usize)
        .map_err(|_| InstructionError::InvalidInstructionData)?
        .saturating_add(program_len))
    }
    /// Offset into the ProgramData account's data of the program bits.
    pub fn programdata_data_offset() -> Result<usize, InstructionError> {
        Self::programdata_len(0)
    }
}

/// Returns the instructions required to initialize a Buffer account.
pub fn create_buffer(
    payer_address: &Pubkey,
    buffer_address: &Pubkey,
    authority_address: &Pubkey,
    lamports: u64,
    program_len: usize,
) -> Result<Vec<Instruction>, InstructionError> {
    Ok(vec![
        system_instruction::create_account(
            payer_address,
            buffer_address,
            lamports,
            UpgradeableLoaderState::buffer_len(program_len)? as u64,
            &id(),
        ),
        Instruction::new(
            id(),
            &UpgradeableLoaderInstruction::InitializeBuffer,
            vec![
                AccountMeta::new(*buffer_address, false),
                AccountMeta::new_readonly(*authority_address, false),
            ],
        ),
    ])
}

/// Returns the instructions required to write a chunk of program data to a
/// buffer account.
pub fn write(
    buffer_address: &Pubkey,
    authority_address: &Pubkey,
    offset: u32,
    bytes: Vec<u8>,
) -> Instruction {
    Instruction::new(
        id(),
        &UpgradeableLoaderInstruction::Write { offset, bytes },
        vec![
            AccountMeta::new(*buffer_address, false),
            AccountMeta::new_readonly(*authority_address, true),
        ],
    )
}

/// Returns the instructions required to deploy a program with a specified
/// maximum program length.  The maximum length must be large enough to
/// accommodate any future upgrades.
pub fn deploy_with_max_program_len(
    payer_address: &Pubkey,
    program_address: &Pubkey,
    buffer_address: &Pubkey,
    upgrade_authority_address: &Pubkey,
    program_lamports: u64,
    max_data_len: usize,
) -> Result<Vec<Instruction>, InstructionError> {
    let (programdata_address, _) = Pubkey::find_program_address(&[program_address.as_ref()], &id());
    Ok(vec![
        system_instruction::create_account(
            payer_address,
            program_address,
            program_lamports,
            UpgradeableLoaderState::program_len()? as u64,
            &id(),
        ),
        Instruction::new(
            id(),
            &UpgradeableLoaderInstruction::DeployWithMaxDataLen { max_data_len },
            vec![
                AccountMeta::new(*payer_address, true),
                AccountMeta::new(programdata_address, false),
                AccountMeta::new(*program_address, false),
                AccountMeta::new(*buffer_address, false),
                AccountMeta::new_readonly(sysvar::rent::id(), false),
                AccountMeta::new_readonly(sysvar::clock::id(), false),
                AccountMeta::new_readonly(crate::system_program::id(), false),
                AccountMeta::new_readonly(*upgrade_authority_address, true),
            ],
        ),
    ])
}

/// Returns the instructions required to upgrade a program.
pub fn upgrade(
    program_address: &Pubkey,
    buffer_address: &Pubkey,
    authority_address: &Pubkey,
    spill_address: &Pubkey,
) -> Instruction {
    let (programdata_address, _) = Pubkey::find_program_address(&[program_address.as_ref()], &id());
    Instruction::new(
        id(),
        &UpgradeableLoaderInstruction::Upgrade,
        vec![
            AccountMeta::new(programdata_address, false),
            AccountMeta::new(*program_address, false),
            AccountMeta::new(*buffer_address, false),
            AccountMeta::new(*spill_address, false),
            AccountMeta::new_readonly(sysvar::rent::id(), false),
            AccountMeta::new_readonly(sysvar::clock::id(), false),
            AccountMeta::new_readonly(*authority_address, true),
        ],
    )
}

pub fn is_upgrade_instruction(instruction_data: &[u8]) -> bool {
    3 == instruction_data[0]
}

/// Returns the instructions required to set a buffers's authority.
pub fn set_buffer_authority(
    buffer_address: &Pubkey,
    current_authority_address: &Pubkey,
    new_authority_address: &Pubkey,
) -> Instruction {
    Instruction::new(
        id(),
        &UpgradeableLoaderInstruction::SetAuthority,
        vec![
            AccountMeta::new(*buffer_address, false),
            AccountMeta::new_readonly(*current_authority_address, true),
            AccountMeta::new_readonly(*new_authority_address, false),
        ],
    )
}

/// Returns the instructions required to set a program's authority.
pub fn set_upgrade_authority(
    program_address: &Pubkey,
    current_authority_address: &Pubkey,
    new_authority_address: Option<&Pubkey>,
) -> Instruction {
    let (programdata_address, _) = Pubkey::find_program_address(&[program_address.as_ref()], &id());

    let mut metas = vec![
        AccountMeta::new(programdata_address, false),
        AccountMeta::new_readonly(*current_authority_address, true),
    ];
    if let Some(address) = new_authority_address {
        metas.push(AccountMeta::new_readonly(*address, false));
    }
    Instruction::new(id(), &UpgradeableLoaderInstruction::SetAuthority, metas)
}

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

    #[test]
    fn test_account_lengths() {
        assert_eq!(
            4,
            serialized_size(&UpgradeableLoaderState::Uninitialized).unwrap()
        );
        assert_eq!(36, UpgradeableLoaderState::program_len().unwrap());
        assert_eq!(
            45,
            UpgradeableLoaderState::programdata_data_offset().unwrap()
        );
        assert_eq!(
            45 + 42,
            UpgradeableLoaderState::programdata_len(42).unwrap()
        );
    }

    #[test]
    fn test_is_upgrade_instruction() {
        assert_eq!(
            false,
            is_upgrade_instruction(
                &bincode::serialize(&UpgradeableLoaderInstruction::InitializeBuffer).unwrap()
            )
        );
        assert_eq!(
            false,
            is_upgrade_instruction(
                &bincode::serialize(&UpgradeableLoaderInstruction::Write {
                    offset: 0,
                    bytes: vec![],
                })
                .unwrap()
            )
        );
        assert_eq!(
            false,
            is_upgrade_instruction(
                &bincode::serialize(&UpgradeableLoaderInstruction::DeployWithMaxDataLen {
                    max_data_len: 0,
                })
                .unwrap()
            )
        );
        assert_eq!(
            true,
            is_upgrade_instruction(
                &bincode::serialize(&UpgradeableLoaderInstruction::Upgrade).unwrap()
            )
        );
        assert_eq!(
            false,
            is_upgrade_instruction(
                &bincode::serialize(&UpgradeableLoaderInstruction::SetAuthority).unwrap()
            )
        );
    }
}