use crate::bank_forks::SnapshotConfig;
use crate::result::{Error, Result};
use crate::snapshot_package::SnapshotPackage;
use crate::snapshot_package::{TAR_ACCOUNTS_DIR, TAR_SNAPSHOTS_DIR};
use bincode::{deserialize_from, serialize_into};
use bzip2::bufread::BzDecoder;
use fs_extra::dir::CopyOptions;
use solana_measure::measure::Measure;
use solana_runtime::bank::Bank;
use solana_runtime::status_cache::SlotDelta;
use solana_sdk::transaction;
use std::cmp::Ordering;
use std::fs;
use std::fs::File;
use std::io::{BufReader, BufWriter, Error as IOError, ErrorKind};
use std::path::{Path, PathBuf};
use tar::Archive;

const SNAPSHOT_STATUS_CACHE_FILE_NAME: &str = "status_cache";

#[derive(PartialEq, Ord, Eq, Debug)]
pub struct SlotSnapshotPaths {
    pub slot: u64,
    pub snapshot_file_path: PathBuf,
    pub snapshot_status_cache_path: PathBuf,
}

impl PartialOrd for SlotSnapshotPaths {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.slot.cmp(&other.slot))
    }
}

impl SlotSnapshotPaths {
    fn hardlink_snapshot_directory<P: AsRef<Path>>(&self, snapshot_hardlink_dir: P) -> Result<()> {
        // Create a new directory in snapshot_hardlink_dir
        let new_slot_hardlink_dir = snapshot_hardlink_dir.as_ref().join(self.slot.to_string());
        let _ = fs::remove_dir_all(&new_slot_hardlink_dir);
        fs::create_dir_all(&new_slot_hardlink_dir)?;

        // Hardlink the snapshot
        fs::hard_link(
            &self.snapshot_file_path,
            &new_slot_hardlink_dir.join(self.slot.to_string()),
        )?;
        // Hardlink the status cache
        fs::hard_link(
            &self.snapshot_status_cache_path,
            &new_slot_hardlink_dir.join(SNAPSHOT_STATUS_CACHE_FILE_NAME),
        )?;
        Ok(())
    }
}

pub fn package_snapshot<P: AsRef<Path>, Q: AsRef<Path>>(
    bank: &Bank,
    snapshot_files: &[SlotSnapshotPaths],
    snapshot_package_output_file: P,
    snapshot_path: Q,
) -> Result<SnapshotPackage> {
    // Hard link all the snapshots we need for this package
    let snapshot_hard_links_dir = tempfile::tempdir_in(snapshot_path)?;

    // Get a reference to all the relevant AccountStorageEntries
    let account_storage_entries: Vec<_> = bank
        .rc
        .get_storage_entries()
        .into_iter()
        .filter(|x| x.fork_id() <= bank.slot())
        .collect();

    // Create a snapshot package
    info!(
        "Snapshot for bank: {} has {} account storage entries",
        bank.slot(),
        account_storage_entries.len()
    );

    // Any errors from this point on will cause the above SnapshotPackage to drop, clearing
    // any temporary state created for the SnapshotPackage (like the snapshot_hard_links_dir)
    for files in snapshot_files {
        files.hardlink_snapshot_directory(snapshot_hard_links_dir.path())?;
    }

    let package = SnapshotPackage::new(
        bank.slot(),
        snapshot_hard_links_dir,
        account_storage_entries,
        snapshot_package_output_file.as_ref().to_path_buf(),
    );

    Ok(package)
}

pub fn get_snapshot_paths<P: AsRef<Path>>(snapshot_path: P) -> Vec<SlotSnapshotPaths>
where
    P: std::fmt::Debug,
{
    match fs::read_dir(&snapshot_path) {
        Ok(paths) => {
            let mut names = paths
                .filter_map(|entry| {
                    entry.ok().and_then(|e| {
                        e.path()
                            .file_name()
                            .and_then(|n| n.to_str().map(|s| s.parse::<u64>().ok()))
                            .unwrap_or(None)
                    })
                })
                .map(|slot| {
                    let snapshot_path = snapshot_path.as_ref().join(slot.to_string());
                    SlotSnapshotPaths {
                        slot,
                        snapshot_file_path: snapshot_path.join(get_snapshot_file_name(slot)),
                        snapshot_status_cache_path: snapshot_path
                            .join(SNAPSHOT_STATUS_CACHE_FILE_NAME),
                    }
                })
                .collect::<Vec<SlotSnapshotPaths>>();

            names.sort();
            names
        }
        Err(err) => {
            info!(
                "Unable to read snapshot directory {:?}: {}",
                snapshot_path, err
            );
            vec![]
        }
    }
}

pub fn add_snapshot<P: AsRef<Path>>(
    snapshot_path: P,
    bank: &Bank,
    slots_since_snapshot: &[u64],
) -> Result<()> {
    let slot = bank.slot();
    // snapshot_path/slot
    let slot_snapshot_dir = get_bank_snapshot_dir(snapshot_path, slot);
    fs::create_dir_all(slot_snapshot_dir.clone()).map_err(Error::from)?;

    // the snapshot is stored as snapshot_path/slot/slot
    let snapshot_file_path = slot_snapshot_dir.join(get_snapshot_file_name(slot));
    // the status cache is stored as snapshot_path/slot/slot_satus_cache
    let snapshot_status_cache_file_path = slot_snapshot_dir.join(SNAPSHOT_STATUS_CACHE_FILE_NAME);
    info!(
        "creating snapshot {}, path: {:?} status_cache: {:?}",
        bank.slot(),
        snapshot_file_path,
        snapshot_status_cache_file_path
    );
    let snapshot_file = File::create(&snapshot_file_path)?;
    // snapshot writer
    let mut snapshot_stream = BufWriter::new(snapshot_file);
    let status_cache = File::create(&snapshot_status_cache_file_path)?;
    // status cache writer
    let mut status_cache_stream = BufWriter::new(status_cache);

    // Create the snapshot
    serialize_into(&mut snapshot_stream, &*bank).map_err(|e| get_io_error(&e.to_string()))?;
    serialize_into(&mut snapshot_stream, &bank.rc).map_err(|e| get_io_error(&e.to_string()))?;

    let mut status_cache_serialize = Measure::start("status_cache_serialize-ms");
    // write the status cache
    serialize_into(
        &mut status_cache_stream,
        &bank.src.slot_deltas(slots_since_snapshot),
    )
    .map_err(|_| get_io_error("serialize bank status cache error"))?;
    status_cache_serialize.stop();
    inc_new_counter_info!(
        "serialize-status-cache-ms",
        status_cache_serialize.as_ms() as usize
    );

    info!(
        "successfully created snapshot {}, path: {:?} status_cache: {:?}",
        bank.slot(),
        snapshot_file_path,
        snapshot_status_cache_file_path
    );

    Ok(())
}

pub fn remove_snapshot<P: AsRef<Path>>(slot: u64, snapshot_path: P) -> Result<()> {
    let slot_snapshot_dir = get_bank_snapshot_dir(&snapshot_path, slot);
    // Remove the snapshot directory for this slot
    fs::remove_dir_all(slot_snapshot_dir)?;
    Ok(())
}

pub fn bank_slot_from_archive<P: AsRef<Path>>(snapshot_tar: P) -> Result<u64> {
    let tempdir = tempfile::TempDir::new()?;
    untar_snapshot_in(&snapshot_tar, &tempdir)?;
    let unpacked_snapshots_dir = tempdir.path().join(TAR_SNAPSHOTS_DIR);
    let snapshot_paths = get_snapshot_paths(&unpacked_snapshots_dir);
    let last_root_paths = snapshot_paths
        .last()
        .ok_or_else(|| get_io_error("No snapshots found in snapshots directory"))?;
    let file = File::open(&last_root_paths.snapshot_file_path)?;
    let mut stream = BufReader::new(file);
    let bank: Bank = deserialize_from(&mut stream).map_err(|e| get_io_error(&e.to_string()))?;
    Ok(bank.slot())
}

pub fn bank_from_archive<P: AsRef<Path>>(
    account_paths: String,
    snapshot_config: &SnapshotConfig,
    snapshot_tar: P,
) -> Result<Bank> {
    // Untar the snapshot into a temp directory under `snapshot_config.snapshot_path()`
    let unpack_dir = tempfile::tempdir_in(&snapshot_config.snapshot_path)?;
    untar_snapshot_in(&snapshot_tar, &unpack_dir)?;

    let unpacked_accounts_dir = unpack_dir.as_ref().join(TAR_ACCOUNTS_DIR);
    let unpacked_snapshots_dir = unpack_dir.as_ref().join(TAR_SNAPSHOTS_DIR);
    let snapshot_paths = get_snapshot_paths(&unpacked_snapshots_dir);
    let bank = rebuild_bank_from_snapshots(account_paths, &snapshot_paths, unpacked_accounts_dir)?;

    // Move the unpacked snapshots into `snapshot_config.snapshot_path`
    let dir_files = fs::read_dir(&unpacked_snapshots_dir).unwrap_or_else(|err| {
        panic!(
            "Invalid snapshot path {:?}: {}",
            unpacked_snapshots_dir, err
        )
    });
    let paths: Vec<PathBuf> = dir_files
        .filter_map(|entry| entry.ok().map(|e| e.path()))
        .collect();
    let mut copy_options = CopyOptions::new();
    copy_options.overwrite = true;
    fs_extra::move_items(&paths, &snapshot_config.snapshot_path, &copy_options)?;

    Ok(bank)
}

pub fn get_snapshot_tar_path<P: AsRef<Path>>(snapshot_output_dir: P) -> PathBuf {
    snapshot_output_dir.as_ref().join("snapshot.tar.bz2")
}

pub fn untar_snapshot_in<P: AsRef<Path>, Q: AsRef<Path>>(
    snapshot_tar: P,
    unpack_dir: Q,
) -> Result<()> {
    let tar_bz2 = File::open(snapshot_tar)?;
    let tar = BzDecoder::new(BufReader::new(tar_bz2));
    let mut archive = Archive::new(tar);
    archive.unpack(&unpack_dir)?;
    Ok(())
}

fn rebuild_bank_from_snapshots<P>(
    local_account_paths: String,
    snapshot_paths: &[SlotSnapshotPaths],
    append_vecs_path: P,
) -> Result<Bank>
where
    P: AsRef<Path>,
{
    // Rebuild the last root bank
    let last_root_paths = snapshot_paths
        .last()
        .ok_or_else(|| get_io_error("No snapshots found in snapshots directory"))?;
    info!("Loading from {:?}", &last_root_paths.snapshot_file_path);
    let file = File::open(&last_root_paths.snapshot_file_path)?;
    let mut stream = BufReader::new(file);
    let bank: Bank = deserialize_from(&mut stream).map_err(|e| get_io_error(&e.to_string()))?;

    // Rebuild accounts
    bank.rc
        .accounts_from_stream(&mut stream, local_account_paths, append_vecs_path)?;

    // merge the status caches from all previous banks
    for slot_paths in snapshot_paths.iter().rev() {
        let status_cache = File::open(&slot_paths.snapshot_status_cache_path)?;
        let mut stream = BufReader::new(status_cache);
        let slot_deltas: Vec<SlotDelta<transaction::Result<()>>> = deserialize_from(&mut stream)
            .map_err(|_| get_io_error("deserialize root error"))
            .unwrap_or_default();

        bank.src.append(&slot_deltas);
    }

    Ok(bank)
}

fn get_snapshot_file_name(slot: u64) -> String {
    slot.to_string()
}

fn get_bank_snapshot_dir<P: AsRef<Path>>(path: P, slot: u64) -> PathBuf {
    path.as_ref().join(slot.to_string())
}

fn get_io_error(error: &str) -> Error {
    warn!("Snapshot Error: {:?}", error);
    Error::IO(IOError::new(ErrorKind::Other, error))
}

#[cfg(test)]
pub mod tests {
    use super::*;
    use crate::snapshot_package::{TAR_ACCOUNTS_DIR, TAR_SNAPSHOTS_DIR};
    use tempfile::TempDir;

    pub fn verify_snapshot_tar<P, Q, R>(
        snapshot_tar: P,
        snapshots_to_verify: Q,
        storages_to_verify: R,
    ) where
        P: AsRef<Path>,
        Q: AsRef<Path>,
        R: AsRef<Path>,
    {
        let temp_dir = TempDir::new().unwrap();
        let unpack_dir = temp_dir.path();
        untar_snapshot_in(snapshot_tar, &unpack_dir).unwrap();

        // Check snapshots are the same
        let unpacked_snapshots = unpack_dir.join(&TAR_SNAPSHOTS_DIR);
        assert!(!dir_diff::is_different(&snapshots_to_verify, unpacked_snapshots).unwrap());

        // Check the account entries are the same
        let unpacked_accounts = unpack_dir.join(&TAR_ACCOUNTS_DIR);
        assert!(!dir_diff::is_different(&storages_to_verify, unpacked_accounts).unwrap());
    }
}