use crate::accounts_db::{
    get_paths_vec, AccountInfo, AccountStorage, AccountsDB, ErrorCounters, InstructionAccounts,
    InstructionLoaders,
};
use crate::accounts_index::{AccountsIndex, Fork};
use crate::append_vec::StoredAccount;
use crate::message_processor::has_duplicates;
use bincode::serialize;
use hashbrown::{HashMap, HashSet};
use log::*;
use solana_metrics::inc_new_counter_error;
use solana_sdk::account::Account;
use solana_sdk::fee_calculator::FeeCalculator;
use solana_sdk::hash::{Hash, Hasher};
use solana_sdk::native_loader;
use solana_sdk::pubkey::Pubkey;
use solana_sdk::signature::{Keypair, KeypairUtil};
use solana_sdk::system_program;
use solana_sdk::transaction::Result;
use solana_sdk::transaction::{Transaction, TransactionError};
use std::borrow::Borrow;
use std::env;
use std::fs::remove_dir_all;
use std::iter::once;
use std::ops::Neg;
use std::path::Path;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::{Arc, Mutex};
use std::thread::sleep;
use std::time::Duration;

const ACCOUNTSDB_DIR: &str = "accountsdb";
const NUM_ACCOUNT_DIRS: usize = 4;
const WAIT_FOR_PARENT_MS: u64 = 5;

#[derive(Clone, PartialEq, Eq, Debug)]
pub enum AccountLockType {
    AccountLock,
    RecordLock,
}

type AccountLocks = Mutex<HashSet<Pubkey>>;

// Locks for accounts that are currently being recorded + committed
type RecordLocks = (
    // Record Locks for the current bank
    Arc<AccountLocks>,
    // Any unreleased record locks from all parent/grandparent banks. We use Arc<Mutex> to
    // avoid copies when calling new_from_parent().
    Vec<Arc<AccountLocks>>,
);

/// This structure handles synchronization for db
#[derive(Default)]
pub struct Accounts {
    /// Single global AccountsDB
    pub accounts_db: Arc<AccountsDB>,

    /// set of accounts which are currently in the pipeline
    account_locks: AccountLocks,

    /// set of accounts which are about to record + commit
    record_locks: Mutex<RecordLocks>,

    /// List of persistent stores
    paths: String,

    /// set to true if object created the directories in paths
    /// when true, delete parents of 'paths' on drop
    own_paths: bool,
}

impl Drop for Accounts {
    fn drop(&mut self) {
        let paths = get_paths_vec(&self.paths);
        paths.iter().for_each(|p| {
            let _ignored = remove_dir_all(p);

            // it is safe to delete the parent
            if self.own_paths {
                let path = Path::new(p);
                let _ignored = remove_dir_all(path.parent().unwrap());
            }
        });
    }
}

impl Accounts {
    fn make_new_dir() -> String {
        static ACCOUNT_DIR: AtomicUsize = AtomicUsize::new(0);
        let dir = ACCOUNT_DIR.fetch_add(1, Ordering::Relaxed);
        let out_dir = env::var("OUT_DIR").unwrap_or_else(|_| "target".to_string());
        let keypair = Keypair::new();
        format!(
            "{}/{}/{}/{}",
            out_dir,
            ACCOUNTSDB_DIR,
            keypair.pubkey(),
            dir.to_string()
        )
    }

    fn make_default_paths() -> String {
        let mut paths = "".to_string();
        for index in 0..NUM_ACCOUNT_DIRS {
            if index > 0 {
                paths.push_str(",");
            }
            paths.push_str(&Self::make_new_dir());
        }
        paths
    }

    pub fn new(in_paths: Option<String>) -> Self {
        let (paths, own_paths) = if in_paths.is_none() {
            (Self::make_default_paths(), true)
        } else {
            (in_paths.unwrap(), false)
        };
        let accounts_db = Arc::new(AccountsDB::new(&paths));
        Accounts {
            accounts_db,
            account_locks: Mutex::new(HashSet::new()),
            record_locks: Mutex::new((Arc::new(Mutex::new(HashSet::new())), vec![])),
            paths,
            own_paths,
        }
    }

    pub fn new_from_parent(parent: &Accounts) -> Self {
        let accounts_db = parent.accounts_db.clone();
        let parent_record_locks: Vec<_> = {
            let (ref record_locks, ref mut grandparent_record_locks) =
                *parent.record_locks.lock().unwrap();

            // Note that when creating a child bank, we only care about the locks that are held for
            // accounts that are in txs that are currently recording + committing, because other
            // incoming txs on this bank that are not yet recording will not make it to bank commit.
            //
            // Thus:
            // 1) The child doesn't need to care about potential "future" account locks on its parent
            // bank that the parent does not currently hold.
            // 2) The child only needs the currently held "record locks" from the parent.
            // 3) The parent doesn't need to retain any of the locks other than the ones it owns so
            // that unlock() can be called later (the grandparent locks can be given to the child).
            once(record_locks.clone())
                .chain(grandparent_record_locks.drain(..))
                .filter(|a| !a.lock().unwrap().is_empty())
                .collect()
        };

        Accounts {
            accounts_db,
            account_locks: Mutex::new(HashSet::new()),
            record_locks: Mutex::new((Arc::new(Mutex::new(HashSet::new())), parent_record_locks)),
            paths: parent.paths.clone(),
            own_paths: parent.own_paths,
        }
    }

    fn load_tx_accounts(
        storage: &AccountStorage,
        ancestors: &HashMap<Fork, usize>,
        accounts_index: &AccountsIndex<AccountInfo>,
        tx: &Transaction,
        fee: u64,
        error_counters: &mut ErrorCounters,
    ) -> Result<Vec<Account>> {
        // Copy all the accounts
        let message = tx.message();
        if tx.signatures.is_empty() && fee != 0 {
            Err(TransactionError::MissingSignatureForFee)
        } else {
            // Check for unique account keys
            if has_duplicates(&message.account_keys) {
                error_counters.account_loaded_twice += 1;
                return Err(TransactionError::AccountLoadedTwice);
            }

            // There is no way to predict what program will execute without an error
            // If a fee can pay for execution then the program will be scheduled
            let mut called_accounts: Vec<Account> = vec![];
            for key in &message.account_keys {
                if !message.program_ids().contains(&key) {
                    called_accounts.push(
                        AccountsDB::load(storage, ancestors, accounts_index, key)
                            .map(|(account, _)| account)
                            .unwrap_or_default(),
                    );
                }
            }
            if called_accounts.is_empty() || called_accounts[0].lamports == 0 {
                error_counters.account_not_found += 1;
                Err(TransactionError::AccountNotFound)
            } else if called_accounts[0].owner != system_program::id() {
                error_counters.invalid_account_for_fee += 1;
                Err(TransactionError::InvalidAccountForFee)
            } else if called_accounts[0].lamports < fee {
                error_counters.insufficient_funds += 1;
                Err(TransactionError::InsufficientFundsForFee)
            } else {
                called_accounts[0].lamports -= fee;
                Ok(called_accounts)
            }
        }
    }

    fn load_executable_accounts(
        storage: &AccountStorage,
        ancestors: &HashMap<Fork, usize>,
        accounts_index: &AccountsIndex<AccountInfo>,
        program_id: &Pubkey,
        error_counters: &mut ErrorCounters,
    ) -> Result<Vec<(Pubkey, Account)>> {
        let mut accounts = Vec::new();
        let mut depth = 0;
        let mut program_id = *program_id;
        loop {
            if native_loader::check_id(&program_id) {
                // at the root of the chain, ready to dispatch
                break;
            }

            if depth >= 5 {
                error_counters.call_chain_too_deep += 1;
                return Err(TransactionError::CallChainTooDeep);
            }
            depth += 1;

            let program = match AccountsDB::load(storage, ancestors, accounts_index, &program_id)
                .map(|(account, _)| account)
            {
                Some(program) => program,
                None => {
                    error_counters.account_not_found += 1;
                    return Err(TransactionError::ProgramAccountNotFound);
                }
            };
            if !program.executable || program.owner == Pubkey::default() {
                error_counters.account_not_found += 1;
                return Err(TransactionError::AccountNotFound);
            }

            // add loader to chain
            program_id = program.owner;
            accounts.insert(0, (program_id, program));
        }
        Ok(accounts)
    }

    /// For each program_id in the transaction, load its loaders.
    fn load_loaders(
        storage: &AccountStorage,
        ancestors: &HashMap<Fork, usize>,
        accounts_index: &AccountsIndex<AccountInfo>,
        tx: &Transaction,
        error_counters: &mut ErrorCounters,
    ) -> Result<Vec<Vec<(Pubkey, Account)>>> {
        let message = tx.message();
        message
            .instructions
            .iter()
            .map(|ix| {
                if message.account_keys.len() <= ix.program_ids_index as usize {
                    error_counters.account_not_found += 1;
                    return Err(TransactionError::AccountNotFound);
                }
                let program_id = message.account_keys[ix.program_ids_index as usize];
                Self::load_executable_accounts(
                    storage,
                    ancestors,
                    accounts_index,
                    &program_id,
                    error_counters,
                )
            })
            .collect()
    }

    fn load_accounts_internal(
        &self,
        ancestors: &HashMap<Fork, usize>,
        txs: &[Transaction],
        lock_results: Vec<Result<()>>,
        fee_calculator: &FeeCalculator,
        error_counters: &mut ErrorCounters,
    ) -> Vec<Result<(InstructionAccounts, InstructionLoaders)>> {
        //PERF: hold the lock to scan for the references, but not to clone the accounts
        //TODO: two locks usually leads to deadlocks, should this be one structure?
        let accounts_index = self.accounts_db.accounts_index.read().unwrap();
        let storage = self.accounts_db.storage.read().unwrap();
        txs.iter()
            .zip(lock_results.into_iter())
            .map(|etx| match etx {
                (tx, Ok(())) => {
                    let fee = fee_calculator.calculate_fee(tx.message());
                    let accounts = Self::load_tx_accounts(
                        &storage,
                        ancestors,
                        &accounts_index,
                        tx,
                        fee,
                        error_counters,
                    )?;
                    let loaders = Self::load_loaders(
                        &storage,
                        ancestors,
                        &accounts_index,
                        tx,
                        error_counters,
                    )?;
                    Ok((accounts, loaders))
                }
                (_, Err(e)) => Err(e),
            })
            .collect()
    }

    /// Slow because lock is held for 1 operation instead of many
    pub fn load_slow(
        &self,
        ancestors: &HashMap<Fork, usize>,
        pubkey: &Pubkey,
    ) -> Option<(Account, Fork)> {
        self.accounts_db
            .load_slow(ancestors, pubkey)
            .filter(|(acc, _)| acc.lamports != 0)
    }

    pub fn load_by_program(&self, fork: Fork, program_id: &Pubkey) -> Vec<(Pubkey, Account)> {
        let accumulator: Vec<Vec<(Pubkey, u64, Account)>> = self.accounts_db.scan_account_storage(
            fork,
            |stored_account: &StoredAccount, accum: &mut Vec<(Pubkey, u64, Account)>| {
                if stored_account.balance.owner == *program_id {
                    let val = (
                        stored_account.meta.pubkey,
                        stored_account.meta.write_version,
                        stored_account.clone_account(),
                    );
                    accum.push(val)
                }
            },
        );
        let mut versions: Vec<(Pubkey, u64, Account)> =
            accumulator.into_iter().flat_map(|x| x).collect();
        versions.sort_by_key(|s| (s.0, (s.1 as i64).neg()));
        versions.dedup_by_key(|s| s.0);
        versions.into_iter().map(|s| (s.0, s.2)).collect()
    }

    /// Slow because lock is held for 1 operation instead of many
    pub fn store_slow(&self, fork: Fork, pubkey: &Pubkey, account: &Account) {
        self.accounts_db.store(fork, &[(pubkey, account)]);
    }

    fn lock_account(
        (fork_locks, parent_locks): (&mut HashSet<Pubkey>, &mut Vec<Arc<AccountLocks>>),
        keys: &[Pubkey],
        error_counters: &mut ErrorCounters,
    ) -> Result<()> {
        // Copy all the accounts
        for k in keys {
            let is_locked = {
                if fork_locks.contains(k) {
                    true
                } else {
                    // Check parent locks. As soon as a set of parent locks is empty,
                    // we can remove it from the list b/c that means the parent has
                    // released the locks.
                    parent_locks.retain(|p| {
                        loop {
                            {
                                // If a parent bank holds a record lock for this account, then loop
                                // until that lock is released
                                let p = p.lock().unwrap();
                                if !p.contains(k) {
                                    break;
                                }
                            }

                            // If a parent is currently recording for this key, then drop lock and wait
                            sleep(Duration::from_millis(WAIT_FOR_PARENT_MS));
                        }

                        let p = p.lock().unwrap();
                        !p.is_empty()
                    });
                    false
                }
            };
            if is_locked {
                error_counters.account_in_use += 1;
                debug!("Account in use: {:?}", k);
                return Err(TransactionError::AccountInUse);
            }
        }
        for k in keys {
            fork_locks.insert(*k);
        }
        Ok(())
    }

    fn lock_record_account(record_locks: &AccountLocks, keys: &[Pubkey]) {
        let mut fork_locks = record_locks.lock().unwrap();
        for k in keys {
            // The fork locks should always be a subset of the account locks, so
            // the account locks should prevent record locks from ever touching the
            // same accounts
            assert!(!fork_locks.contains(k));
            fork_locks.insert(*k);
        }
    }

    fn unlock_account(tx: &Transaction, result: &Result<()>, locks: &mut HashSet<Pubkey>) {
        match result {
            Err(TransactionError::AccountInUse) => (),
            _ => {
                for k in &tx.message().account_keys {
                    locks.remove(k);
                }
            }
        }
    }

    fn unlock_record_account<I>(tx: &I, locks: &mut HashSet<Pubkey>)
    where
        I: Borrow<Transaction>,
    {
        for k in &tx.borrow().message().account_keys {
            locks.remove(k);
        }
    }

    fn hash_account(stored_account: &StoredAccount) -> Hash {
        let mut hasher = Hasher::default();
        hasher.hash(&serialize(&stored_account.balance).unwrap());
        hasher.hash(stored_account.data);
        hasher.result()
    }

    pub fn hash_internal_state(&self, fork_id: Fork) -> Option<Hash> {
        let accumulator: Vec<Vec<(Pubkey, u64, Hash)>> = self.accounts_db.scan_account_storage(
            fork_id,
            |stored_account: &StoredAccount, accum: &mut Vec<(Pubkey, u64, Hash)>| {
                accum.push((
                    stored_account.meta.pubkey,
                    stored_account.meta.write_version,
                    Self::hash_account(stored_account),
                ));
            },
        );
        let mut account_hashes: Vec<_> = accumulator.into_iter().flat_map(|x| x).collect();
        account_hashes.sort_by_key(|s| (s.0, (s.1 as i64).neg()));
        account_hashes.dedup_by_key(|s| s.0);
        if account_hashes.is_empty() {
            None
        } else {
            let mut hasher = Hasher::default();
            for (_, _, hash) in account_hashes {
                hasher.hash(hash.as_ref());
            }
            Some(hasher.result())
        }
    }

    /// This function will prevent multiple threads from modifying the same account state at the
    /// same time
    #[must_use]
    pub fn lock_accounts<I>(&self, txs: &[I]) -> Vec<Result<()>>
    where
        I: Borrow<Transaction>,
    {
        let (_, ref mut parent_record_locks) = *self.record_locks.lock().unwrap();
        let mut error_counters = ErrorCounters::default();
        let rv = txs
            .iter()
            .map(|tx| {
                let message = tx.borrow().message();
                Self::lock_account(
                    (&mut self.account_locks.lock().unwrap(), parent_record_locks),
                    &message.account_keys[..(message.account_keys.len()
                        - message.header.num_credit_only_unsigned_accounts as usize)],
                    &mut error_counters,
                )
            })
            .collect();
        if error_counters.account_in_use != 0 {
            inc_new_counter_error!(
                "bank-process_transactions-account_in_use",
                error_counters.account_in_use,
                0,
                100
            );
        }
        rv
    }

    pub fn lock_record_accounts<I>(&self, txs: &[I])
    where
        I: Borrow<Transaction>,
    {
        let record_locks = self.record_locks.lock().unwrap();
        for tx in txs {
            let message = tx.borrow().message();
            Self::lock_record_account(
                &record_locks.0,
                &message.account_keys[..(message.account_keys.len()
                    - message.header.num_credit_only_unsigned_accounts as usize)],
            );
        }
    }

    /// Once accounts are unlocked, new transactions that modify that state can enter the pipeline
    pub fn unlock_accounts<I>(&self, txs: &[I], results: &[Result<()>])
    where
        I: Borrow<Transaction>,
    {
        let my_locks = &mut self.account_locks.lock().unwrap();
        debug!("bank unlock accounts");
        txs.iter()
            .zip(results.iter())
            .for_each(|(tx, result)| Self::unlock_account(tx.borrow(), result, my_locks));
    }

    pub fn unlock_record_accounts<I>(&self, txs: &[I])
    where
        I: Borrow<Transaction>,
    {
        let (ref my_record_locks, _) = *self.record_locks.lock().unwrap();
        for tx in txs {
            Self::unlock_record_account(tx, &mut my_record_locks.lock().unwrap())
        }
    }

    pub fn has_accounts(&self, fork: Fork) -> bool {
        self.accounts_db.has_accounts(fork)
    }

    pub fn load_accounts(
        &self,
        ancestors: &HashMap<Fork, usize>,
        txs: &[Transaction],
        results: Vec<Result<()>>,
        fee_calculator: &FeeCalculator,
        error_counters: &mut ErrorCounters,
    ) -> Vec<Result<(InstructionAccounts, InstructionLoaders)>> {
        self.load_accounts_internal(ancestors, txs, results, fee_calculator, error_counters)
    }

    /// Store the accounts into the DB
    pub fn store_accounts(
        &self,
        fork: Fork,
        txs: &[Transaction],
        res: &[Result<()>],
        loaded: &[Result<(InstructionAccounts, InstructionLoaders)>],
    ) {
        let mut accounts: Vec<(&Pubkey, &Account)> = vec![];
        for (i, raccs) in loaded.iter().enumerate() {
            if res[i].is_err() || raccs.is_err() {
                continue;
            }

            let message = &txs[i].message();
            let acc = raccs.as_ref().unwrap();
            for (key, account) in message.account_keys.iter().zip(acc.0.iter()) {
                accounts.push((key, account));
            }
        }
        self.accounts_db.store(fork, &accounts);
    }

    /// Purge a fork if it is not a root
    /// Root forks cannot be purged
    pub fn purge_fork(&self, fork: Fork) {
        self.accounts_db.purge_fork(fork);
    }
    /// Add a fork to root.  Root forks cannot be purged
    pub fn add_root(&self, fork: Fork) {
        self.accounts_db.add_root(fork)
    }
}

#[cfg(test)]
mod tests {
    // TODO: all the bank tests are bank specific, issue: 2194

    use super::*;
    use solana_sdk::account::Account;
    use solana_sdk::hash::Hash;
    use solana_sdk::instruction::CompiledInstruction;
    use solana_sdk::signature::{Keypair, KeypairUtil};
    use solana_sdk::transaction::Transaction;
    use std::thread::{sleep, Builder};
    use std::time::Duration;

    fn load_accounts_with_fee(
        tx: Transaction,
        ka: &Vec<(Pubkey, Account)>,
        fee_calculator: &FeeCalculator,
        error_counters: &mut ErrorCounters,
    ) -> Vec<Result<(InstructionAccounts, InstructionLoaders)>> {
        let accounts = Accounts::new(None);
        for ka in ka.iter() {
            accounts.store_slow(0, &ka.0, &ka.1);
        }

        let ancestors = vec![(0, 0)].into_iter().collect();
        let res = accounts.load_accounts(
            &ancestors,
            &[tx],
            vec![Ok(())],
            &fee_calculator,
            error_counters,
        );
        res
    }

    fn load_accounts(
        tx: Transaction,
        ka: &Vec<(Pubkey, Account)>,
        error_counters: &mut ErrorCounters,
    ) -> Vec<Result<(InstructionAccounts, InstructionLoaders)>> {
        let fee_calculator = FeeCalculator::default();
        load_accounts_with_fee(tx, ka, &fee_calculator, error_counters)
    }

    #[test]
    fn test_load_accounts_no_key() {
        let accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let instructions = vec![CompiledInstruction::new(0, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions::<Keypair>(
            &[],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(loaded_accounts[0], Err(TransactionError::AccountNotFound));
    }

    #[test]
    fn test_load_accounts_no_account_0_exists() {
        let accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(loaded_accounts[0], Err(TransactionError::AccountNotFound));
    }

    #[test]
    fn test_load_accounts_unknown_program_id() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let account = Account::new(2, 1, &Pubkey::default());
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![Pubkey::default()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            Err(TransactionError::ProgramAccountNotFound)
        );
    }

    #[test]
    fn test_load_accounts_insufficient_funds() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let fee_calculator = FeeCalculator::new(10);
        assert_eq!(fee_calculator.calculate_fee(tx.message()), 10);

        let loaded_accounts =
            load_accounts_with_fee(tx, &accounts, &fee_calculator, &mut error_counters);

        assert_eq!(error_counters.insufficient_funds, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            Err(TransactionError::InsufficientFundsForFee)
        );
    }

    #[test]
    fn test_load_accounts_invalid_account_for_fee() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();

        let account = Account::new(1, 1, &Pubkey::new_rand()); // <-- owner is not the system program
        accounts.push((key0, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_account_for_fee, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            Err(TransactionError::InvalidAccountForFee)
        );
    }

    #[test]
    fn test_load_accounts_no_loaders() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let account = Account::new(2, 1, &Pubkey::default());
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[key1],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 0);
        assert_eq!(loaded_accounts.len(), 1);
        match &loaded_accounts[0] {
            Ok((a, l)) => {
                assert_eq!(a.len(), 2);
                assert_eq!(a[0], accounts[0].1);
                assert_eq!(l.len(), 1);
                assert_eq!(l[0].len(), 0);
            }
            Err(e) => Err(e).unwrap(),
        }
    }

    #[test]
    fn test_load_accounts_max_call_depth() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);
        let key3 = Pubkey::new(&[7u8; 32]);
        let key4 = Pubkey::new(&[8u8; 32]);
        let key5 = Pubkey::new(&[9u8; 32]);
        let key6 = Pubkey::new(&[10u8; 32]);

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let mut account = Account::new(40, 1, &Pubkey::default());
        account.executable = true;
        account.owner = native_loader::id();
        accounts.push((key1, account));

        let mut account = Account::new(41, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key1;
        accounts.push((key2, account));

        let mut account = Account::new(42, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key2;
        accounts.push((key3, account));

        let mut account = Account::new(43, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key3;
        accounts.push((key4, account));

        let mut account = Account::new(44, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key4;
        accounts.push((key5, account));

        let mut account = Account::new(45, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key5;
        accounts.push((key6, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key6],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.call_chain_too_deep, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(loaded_accounts[0], Err(TransactionError::CallChainTooDeep));
    }

    #[test]
    fn test_load_accounts_bad_program_id() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let mut account = Account::new(40, 1, &Pubkey::default());
        account.executable = true;
        account.owner = Pubkey::default();
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(0, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key1],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(loaded_accounts[0], Err(TransactionError::AccountNotFound));
    }

    #[test]
    fn test_load_accounts_not_executable() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let mut account = Account::new(40, 1, &Pubkey::default());
        account.owner = native_loader::id();
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key1],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(loaded_accounts[0], Err(TransactionError::AccountNotFound));
    }

    #[test]
    fn test_load_accounts_multiple_loaders() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);
        let key3 = Pubkey::new(&[7u8; 32]);

        let account = Account::new(1, 1, &Pubkey::default());
        accounts.push((key0, account));

        let mut account = Account::new(40, 1, &Pubkey::default());
        account.executable = true;
        account.owner = native_loader::id();
        accounts.push((key1, account));

        let mut account = Account::new(41, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key1;
        accounts.push((key2, account));

        let mut account = Account::new(42, 1, &Pubkey::default());
        account.executable = true;
        account.owner = key2;
        accounts.push((key3, account));

        let instructions = vec![
            CompiledInstruction::new(1, &(), vec![0]),
            CompiledInstruction::new(2, &(), vec![0]),
        ];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key1, key2],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 0);
        assert_eq!(loaded_accounts.len(), 1);
        match &loaded_accounts[0] {
            Ok((a, l)) => {
                assert_eq!(a.len(), 1);
                assert_eq!(a[0], accounts[0].1);
                assert_eq!(l.len(), 2);
                assert_eq!(l[0].len(), 1);
                assert_eq!(l[1].len(), 2);
                for instruction_loaders in l.iter() {
                    for (i, a) in instruction_loaders.iter().enumerate() {
                        // +1 to skip first not loader account
                        assert_eq![a.1, accounts[i + 1].1];
                    }
                }
            }
            Err(e) => Err(e).unwrap(),
        }
    }

    #[test]
    fn test_load_account_pay_to_self() {
        let mut accounts: Vec<(Pubkey, Account)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let pubkey = keypair.pubkey();

        let account = Account::new(10, 1, &Pubkey::default());
        accounts.push((pubkey, account));

        let instructions = vec![CompiledInstruction::new(0, &(), vec![0, 1])];
        // Simulate pay-to-self transaction, which loads the same account twice
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[pubkey],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_loaded_twice, 1);
        assert_eq!(loaded_accounts.len(), 1);
        loaded_accounts[0].clone().unwrap_err();
        assert_eq!(
            loaded_accounts[0],
            Err(TransactionError::AccountLoadedTwice)
        );
    }

    #[test]
    fn test_load_by_program() {
        let accounts = Accounts::new(None);

        // Load accounts owned by various programs into AccountsDB
        let pubkey0 = Pubkey::new_rand();
        let account0 = Account::new(1, 0, &Pubkey::new(&[2; 32]));
        accounts.store_slow(0, &pubkey0, &account0);
        let pubkey1 = Pubkey::new_rand();
        let account1 = Account::new(1, 0, &Pubkey::new(&[2; 32]));
        accounts.store_slow(0, &pubkey1, &account1);
        let pubkey2 = Pubkey::new_rand();
        let account2 = Account::new(1, 0, &Pubkey::new(&[3; 32]));
        accounts.store_slow(0, &pubkey2, &account2);

        let loaded = accounts.load_by_program(0, &Pubkey::new(&[2; 32]));
        assert_eq!(loaded.len(), 2);
        let loaded = accounts.load_by_program(0, &Pubkey::new(&[3; 32]));
        assert_eq!(loaded, vec![(pubkey2, account2)]);
        let loaded = accounts.load_by_program(0, &Pubkey::new(&[4; 32]));
        assert_eq!(loaded, vec![]);
    }

    #[test]
    fn test_accounts_account_not_found() {
        let accounts = Accounts::new(None);
        let mut error_counters = ErrorCounters::default();
        let ancestors = vec![(0, 0)].into_iter().collect();

        let accounts_index = accounts.accounts_db.accounts_index.read().unwrap();
        let storage = accounts.accounts_db.storage.read().unwrap();
        assert_eq!(
            Accounts::load_executable_accounts(
                &storage,
                &ancestors,
                &accounts_index,
                &Pubkey::new_rand(),
                &mut error_counters
            ),
            Err(TransactionError::ProgramAccountNotFound)
        );
        assert_eq!(error_counters.account_not_found, 1);
    }

    #[test]
    fn test_accounts_empty_hash_internal_state() {
        let accounts = Accounts::new(None);
        assert_eq!(accounts.hash_internal_state(0), None);
    }

    #[test]
    fn test_parent_locked_record_accounts() {
        let mut parent = Accounts::new(None);
        let locked_pubkey = Keypair::new().pubkey();
        let mut locked_accounts = HashSet::new();
        locked_accounts.insert(locked_pubkey);
        parent.record_locks = Mutex::new((Arc::new(Mutex::new(locked_accounts.clone())), vec![]));
        let parent = Arc::new(parent);
        let child = Accounts::new_from_parent(&parent);

        // Make sure child record locks contains the parent's locked record accounts
        {
            let (_, ref parent_record_locks) = *child.record_locks.lock().unwrap();
            assert_eq!(parent_record_locks.len(), 1);
            assert_eq!(locked_accounts, *parent_record_locks[0].lock().unwrap());
        }

        let parent_ = parent.clone();
        let parent_thread = Builder::new()
            .name("exit".to_string())
            .spawn(move || {
                sleep(Duration::from_secs(2));
                // Unlock the accounts in the parent
                {
                    let (ref parent_record_locks, _) = *parent_.record_locks.lock().unwrap();
                    parent_record_locks.lock().unwrap().clear();
                }
            })
            .unwrap();

        // Function will block until the parent_thread unlocks the parent's record lock
        assert_eq!(
            Accounts::lock_account(
                (
                    &mut child.account_locks.lock().unwrap(),
                    &mut child.record_locks.lock().unwrap().1
                ),
                &vec![locked_pubkey],
                &mut ErrorCounters::default()
            ),
            Ok(())
        );
        // Make sure that the function blocked
        parent_thread.join().unwrap();

        {
            // Check the lock was successfully obtained
            let child_account_locks = &mut child.account_locks.lock().unwrap();
            let parent_record_locks = child.record_locks.lock().unwrap();
            assert_eq!(child_account_locks.len(), 1);

            // Make sure child removed the parent's record locks after the parent had
            // released all its locks
            assert!(parent_record_locks.1.is_empty());

            // After all the checks pass, clear the account we just locked from the
            // set of locks
            child_account_locks.clear();
        }

        // Make sure calling new_from_parent() on the child bank also cleans up the copy of old locked
        // parent accounts, in case the child doesn't call lock_account() after a parent has
        // released their account locks
        {
            // Mock an empty set of parent record accounts in the child bank
            let (_, ref mut parent_record_locks) = *child.record_locks.lock().unwrap();
            parent_record_locks.push(Arc::new(Mutex::new(HashSet::new())));
        }

        // Call new_from_parent, make sure the empty parent locked_accounts is purged
        let child2 = Accounts::new_from_parent(&child);
        {
            let (_, ref mut parent_record_locks) = *child.record_locks.lock().unwrap();
            assert!(parent_record_locks.is_empty());
            let (_, ref mut parent_record_locks2) = *child2.record_locks.lock().unwrap();
            assert!(parent_record_locks2.is_empty());
        }
    }
}