use {
    crate::{
        accounts::Accounts,
        accounts_db::AccountStorageEntry,
        accounts_hash::{AccountsHash, AccountsHashEnum},
        bank::Bank,
        epoch_accounts_hash::EpochAccountsHash,
        rent_collector::RentCollector,
        snapshot_archive_info::{SnapshotArchiveInfo, SnapshotArchiveInfoGetter},
        snapshot_hash::SnapshotHash,
        snapshot_utils::{
            self, ArchiveFormat, BankSnapshotInfo, Result, SnapshotVersion,
            SNAPSHOT_STATUS_CACHE_FILENAME, TMP_BANK_SNAPSHOT_PREFIX,
        },
    },
    log::*,
    solana_sdk::{clock::Slot, feature_set, sysvar::epoch_schedule::EpochSchedule},
    std::{
        fs,
        path::{Path, PathBuf},
        sync::Arc,
        time::Instant,
    },
    tempfile::TempDir,
};

mod compare;
pub use compare::*;

/// This struct packages up fields to send from AccountsBackgroundService to AccountsHashVerifier
pub struct AccountsPackage {
    pub package_type: AccountsPackageType,
    pub slot: Slot,
    pub block_height: Slot,
    pub snapshot_storages: Vec<Arc<AccountStorageEntry>>,
    pub expected_capitalization: u64,
    pub accounts_hash_for_testing: Option<AccountsHash>,
    pub accounts: Arc<Accounts>,
    pub epoch_schedule: EpochSchedule,
    pub rent_collector: RentCollector,
    pub is_incremental_accounts_hash_feature_enabled: bool,

    /// Supplemental information needed for snapshots
    pub snapshot_info: Option<SupplementalSnapshotInfo>,

    /// The instant this accounts package was send to the queue.
    /// Used to track how long accounts packages wait before processing.
    pub enqueued: Instant,
}

impl AccountsPackage {
    /// Package up bank files, storages, and slot deltas for a snapshot
    #[allow(clippy::too_many_arguments)]
    pub fn new_for_snapshot(
        package_type: AccountsPackageType,
        bank: &Bank,
        bank_snapshot_info: &BankSnapshotInfo,
        bank_snapshots_dir: impl AsRef<Path>,
        full_snapshot_archives_dir: impl AsRef<Path>,
        incremental_snapshot_archives_dir: impl AsRef<Path>,
        snapshot_storages: Vec<Arc<AccountStorageEntry>>,
        archive_format: ArchiveFormat,
        snapshot_version: SnapshotVersion,
        accounts_hash_for_testing: Option<AccountsHash>,
    ) -> Result<Self> {
        if let AccountsPackageType::Snapshot(snapshot_type) = package_type {
            info!(
                "Package snapshot for bank {} has {} account storage entries (snapshot type: {:?})",
                bank.slot(),
                snapshot_storages.len(),
                snapshot_type,
            );
            if let SnapshotType::IncrementalSnapshot(incremental_snapshot_base_slot) = snapshot_type
            {
                assert!(
                    bank.slot() > incremental_snapshot_base_slot,
                    "Incremental snapshot base slot must be less than the bank being snapshotted!"
                );
            }
        }

        // Hard link the snapshot into a tmpdir, to ensure its not removed prior to packaging.
        let snapshot_links = tempfile::Builder::new()
            .prefix(&format!("{}{}-", TMP_BANK_SNAPSHOT_PREFIX, bank.slot()))
            .tempdir_in(bank_snapshots_dir)?;
        {
            let snapshot_hardlink_dir = snapshot_links
                .path()
                .join(bank_snapshot_info.slot.to_string());
            fs::create_dir_all(&snapshot_hardlink_dir)?;
            let snapshot_path = bank_snapshot_info.snapshot_path();
            let file_name = snapshot_utils::path_to_file_name_str(&snapshot_path)?;
            fs::hard_link(&snapshot_path, snapshot_hardlink_dir.join(file_name))?;
            let status_cache_path = bank_snapshot_info
                .snapshot_dir
                .join(SNAPSHOT_STATUS_CACHE_FILENAME);
            let status_cache_file_name = snapshot_utils::path_to_file_name_str(&status_cache_path)?;
            fs::hard_link(
                &status_cache_path,
                snapshot_links.path().join(status_cache_file_name),
            )?;
        }

        let snapshot_info = SupplementalSnapshotInfo {
            snapshot_links,
            archive_format,
            snapshot_version,
            full_snapshot_archives_dir: full_snapshot_archives_dir.as_ref().to_path_buf(),
            incremental_snapshot_archives_dir: incremental_snapshot_archives_dir
                .as_ref()
                .to_path_buf(),
            epoch_accounts_hash: bank.get_epoch_accounts_hash_to_serialize(),
        };
        Ok(Self::_new(
            package_type,
            bank,
            snapshot_storages,
            accounts_hash_for_testing,
            Some(snapshot_info),
        ))
    }

    /// Package up fields needed to compute an EpochAccountsHash
    #[must_use]
    pub fn new_for_epoch_accounts_hash(
        package_type: AccountsPackageType,
        bank: &Bank,
        snapshot_storages: Vec<Arc<AccountStorageEntry>>,
        accounts_hash_for_testing: Option<AccountsHash>,
    ) -> Self {
        assert_eq!(package_type, AccountsPackageType::EpochAccountsHash);
        Self::_new(
            package_type,
            bank,
            snapshot_storages,
            accounts_hash_for_testing,
            None,
        )
    }

    fn _new(
        package_type: AccountsPackageType,
        bank: &Bank,
        snapshot_storages: Vec<Arc<AccountStorageEntry>>,
        accounts_hash_for_testing: Option<AccountsHash>,
        snapshot_info: Option<SupplementalSnapshotInfo>,
    ) -> Self {
        let is_incremental_accounts_hash_feature_enabled = bank
            .feature_set
            .is_active(&feature_set::incremental_snapshot_only_incremental_hash_calculation::id());
        Self {
            package_type,
            slot: bank.slot(),
            block_height: bank.block_height(),
            snapshot_storages,
            expected_capitalization: bank.capitalization(),
            accounts_hash_for_testing,
            accounts: bank.accounts(),
            epoch_schedule: *bank.epoch_schedule(),
            rent_collector: bank.rent_collector().clone(),
            is_incremental_accounts_hash_feature_enabled,
            snapshot_info,
            enqueued: Instant::now(),
        }
    }

    /// Create a new Accounts Package where basically every field is defaulted.
    /// Only use for tests; many of the fields are invalid!
    pub fn default_for_tests() -> Self {
        Self {
            package_type: AccountsPackageType::AccountsHashVerifier,
            slot: Slot::default(),
            block_height: Slot::default(),
            snapshot_storages: Vec::default(),
            expected_capitalization: u64::default(),
            accounts_hash_for_testing: Option::default(),
            accounts: Arc::new(Accounts::default_for_tests()),
            epoch_schedule: EpochSchedule::default(),
            rent_collector: RentCollector::default(),
            is_incremental_accounts_hash_feature_enabled: bool::default(),
            snapshot_info: Some(SupplementalSnapshotInfo {
                snapshot_links: TempDir::new().unwrap(),
                archive_format: ArchiveFormat::Tar,
                snapshot_version: SnapshotVersion::default(),
                full_snapshot_archives_dir: PathBuf::default(),
                incremental_snapshot_archives_dir: PathBuf::default(),
                epoch_accounts_hash: Option::default(),
            }),
            enqueued: Instant::now(),
        }
    }

    /// Returns the path to the snapshot links directory
    ///
    /// NOTE 1: This path is within the TempDir created for the AccountsPackage, *not* the bank
    ///         snapshots dir passed into `new_for_snapshot()` when creating the AccountsPackage.
    /// NOTE 2: This fn will panic if the AccountsPackage is of type EpochAccountsHash.
    pub fn snapshot_links_dir(&self) -> &Path {
        match self.package_type {
            AccountsPackageType::AccountsHashVerifier | AccountsPackageType::Snapshot(..) => {
                self.snapshot_info.as_ref().unwrap().snapshot_links.path()
            }
            AccountsPackageType::EpochAccountsHash => {
                panic!("EAH accounts packages do not contain snapshot information")
            }
        }
    }
}

impl std::fmt::Debug for AccountsPackage {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("AccountsPackage")
            .field("type", &self.package_type)
            .field("slot", &self.slot)
            .field("block_height", &self.block_height)
            .finish_non_exhaustive()
    }
}

/// Supplemental information needed for snapshots
pub struct SupplementalSnapshotInfo {
    pub snapshot_links: TempDir,
    pub archive_format: ArchiveFormat,
    pub snapshot_version: SnapshotVersion,
    pub full_snapshot_archives_dir: PathBuf,
    pub incremental_snapshot_archives_dir: PathBuf,
    pub epoch_accounts_hash: Option<EpochAccountsHash>,
}

/// Accounts packages are sent to the Accounts Hash Verifier for processing.  There are multiple
/// types of accounts packages, which are specified as variants in this enum.  All accounts
/// packages do share some processing: such as calculating the accounts hash.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum AccountsPackageType {
    AccountsHashVerifier,
    Snapshot(SnapshotType),
    EpochAccountsHash,
}

/// This struct packages up fields to send from AccountsHashVerifier to SnapshotPackagerService
pub struct SnapshotPackage {
    pub snapshot_archive_info: SnapshotArchiveInfo,
    pub block_height: Slot,
    pub snapshot_links: TempDir,
    pub snapshot_storages: Vec<Arc<AccountStorageEntry>>,
    pub snapshot_version: SnapshotVersion,
    pub snapshot_type: SnapshotType,

    /// The instant this snapshot package was sent to the queue.
    /// Used to track how long snapshot packages wait before handling.
    pub enqueued: Instant,
}

impl SnapshotPackage {
    pub fn new(accounts_package: AccountsPackage, accounts_hash: AccountsHashEnum) -> Self {
        let AccountsPackageType::Snapshot(snapshot_type) = accounts_package.package_type else {
            panic!("The AccountsPackage must be of type Snapshot in order to make a SnapshotPackage!");
        };
        let Some(snapshot_info) = accounts_package.snapshot_info else {
            panic!("The AccountsPackage must have snapshot info in order to make a SnapshotPackage!");
        };
        let snapshot_hash =
            SnapshotHash::new(&accounts_hash, snapshot_info.epoch_accounts_hash.as_ref());
        let mut snapshot_storages = accounts_package.snapshot_storages;
        let snapshot_archive_path = match snapshot_type {
            SnapshotType::FullSnapshot => snapshot_utils::build_full_snapshot_archive_path(
                snapshot_info.full_snapshot_archives_dir,
                accounts_package.slot,
                &snapshot_hash,
                snapshot_info.archive_format,
            ),
            SnapshotType::IncrementalSnapshot(incremental_snapshot_base_slot) => {
                snapshot_storages.retain(|storage| storage.slot() > incremental_snapshot_base_slot);
                assert!(
                    snapshot_storages.iter().all(|storage| storage.slot() > incremental_snapshot_base_slot),
                    "Incremental snapshot package must only contain storage entries where slot > incremental snapshot base slot (i.e. full snapshot slot)!"
                );
                snapshot_utils::build_incremental_snapshot_archive_path(
                    snapshot_info.incremental_snapshot_archives_dir,
                    incremental_snapshot_base_slot,
                    accounts_package.slot,
                    &snapshot_hash,
                    snapshot_info.archive_format,
                )
            }
        };

        Self {
            snapshot_archive_info: SnapshotArchiveInfo {
                path: snapshot_archive_path,
                slot: accounts_package.slot,
                hash: snapshot_hash,
                archive_format: snapshot_info.archive_format,
            },
            block_height: accounts_package.block_height,
            snapshot_links: snapshot_info.snapshot_links,
            snapshot_storages,
            snapshot_version: snapshot_info.snapshot_version,
            snapshot_type,
            enqueued: Instant::now(),
        }
    }
}

impl std::fmt::Debug for SnapshotPackage {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("SnapshotPackage")
            .field("type", &self.snapshot_type)
            .field("slot", &self.slot())
            .field("block_height", &self.block_height)
            .finish_non_exhaustive()
    }
}

impl SnapshotArchiveInfoGetter for SnapshotPackage {
    fn snapshot_archive_info(&self) -> &SnapshotArchiveInfo {
        &self.snapshot_archive_info
    }
}

/// Snapshots come in two flavors, Full and Incremental.  The IncrementalSnapshot has a Slot field,
/// which is the incremental snapshot base slot.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum SnapshotType {
    FullSnapshot,
    IncrementalSnapshot(Slot),
}

impl SnapshotType {
    pub fn is_full_snapshot(&self) -> bool {
        matches!(self, SnapshotType::FullSnapshot)
    }
    pub fn is_incremental_snapshot(&self) -> bool {
        matches!(self, SnapshotType::IncrementalSnapshot(_))
    }
}

/// Helper function to retain only max n of elements to the right of a vector,
/// viz. remove v.len() - n elements from the left of the vector.
#[inline(always)]
pub fn retain_max_n_elements<T>(v: &mut Vec<T>, n: usize) {
    if v.len() > n {
        let to_truncate = v.len() - n;
        v.rotate_left(to_truncate);
        v.truncate(n);
    }
}