use beacon_chain::{
    builder::Witness, eth1_chain::CachingEth1Backend, schema_change::migrate_schema,
    slot_clock::SystemTimeSlotClock,
};
use beacon_node::{get_data_dir, get_slots_per_restore_point, ClientConfig};
use clap::{App, Arg, ArgMatches};
use environment::{Environment, RuntimeContext};
use slog::{info, Logger};
use store::{
    errors::Error,
    metadata::{SchemaVersion, CURRENT_SCHEMA_VERSION},
    DBColumn, HotColdDB, KeyValueStore, LevelDB,
};
use strum::{EnumString, EnumVariantNames, VariantNames};
use types::EthSpec;

pub const CMD: &str = "database_manager";

pub fn version_cli_app<'a, 'b>() -> App<'a, 'b> {
    App::new("version")
        .visible_aliases(&["v"])
        .setting(clap::AppSettings::ColoredHelp)
        .about("Display database schema version")
}

pub fn migrate_cli_app<'a, 'b>() -> App<'a, 'b> {
    App::new("migrate")
        .setting(clap::AppSettings::ColoredHelp)
        .about("Migrate the database to a specific schema version")
        .arg(
            Arg::with_name("to")
                .long("to")
                .value_name("VERSION")
                .help("Schema version to migrate to")
                .takes_value(true)
                .required(true),
        )
}

pub fn inspect_cli_app<'a, 'b>() -> App<'a, 'b> {
    App::new("inspect")
        .setting(clap::AppSettings::ColoredHelp)
        .about("Inspect raw database values")
        .arg(
            Arg::with_name("column")
                .long("column")
                .value_name("TAG")
                .help("3-byte column ID (see `DBColumn`)")
                .takes_value(true)
                .required(true),
        )
        .arg(
            Arg::with_name("output")
                .long("output")
                .value_name("TARGET")
                .help("Select the type of output to show")
                .default_value("sizes")
                .possible_values(InspectTarget::VARIANTS),
        )
}

pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
    App::new(CMD)
        .visible_aliases(&["db"])
        .setting(clap::AppSettings::ColoredHelp)
        .about("Manage a beacon node database")
        .arg(
            Arg::with_name("slots-per-restore-point")
                .long("slots-per-restore-point")
                .value_name("SLOT_COUNT")
                .help(
                    "Specifies how often a freezer DB restore point should be stored. \
                       Cannot be changed after initialization. \
                       [default: 2048 (mainnet) or 64 (minimal)]",
                )
                .takes_value(true),
        )
        .arg(
            Arg::with_name("freezer-dir")
                .long("freezer-dir")
                .value_name("DIR")
                .help("Data directory for the freezer database.")
                .takes_value(true),
        )
        .subcommand(migrate_cli_app())
        .subcommand(version_cli_app())
        .subcommand(inspect_cli_app())
}

fn parse_client_config<E: EthSpec>(
    cli_args: &ArgMatches,
    _env: &Environment<E>,
) -> Result<ClientConfig, String> {
    let mut client_config = ClientConfig {
        data_dir: get_data_dir(cli_args),
        ..Default::default()
    };

    if let Some(freezer_dir) = clap_utils::parse_optional(cli_args, "freezer-dir")? {
        client_config.freezer_db_path = Some(freezer_dir);
    }

    let (sprp, sprp_explicit) = get_slots_per_restore_point::<E>(cli_args)?;
    client_config.store.slots_per_restore_point = sprp;
    client_config.store.slots_per_restore_point_set_explicitly = sprp_explicit;

    Ok(client_config)
}

pub fn display_db_version<E: EthSpec>(
    client_config: ClientConfig,
    runtime_context: &RuntimeContext<E>,
    log: Logger,
) -> Result<(), Error> {
    let spec = runtime_context.eth2_config.spec.clone();
    let hot_path = client_config.get_db_path();
    let cold_path = client_config.get_freezer_db_path();

    let mut version = CURRENT_SCHEMA_VERSION;
    HotColdDB::<E, LevelDB<E>, LevelDB<E>>::open(
        &hot_path,
        &cold_path,
        |_, from, _| {
            version = from;
            Ok(())
        },
        client_config.store,
        spec,
        log.clone(),
    )?;

    info!(log, "Database version: {}", version.as_u64());

    if version != CURRENT_SCHEMA_VERSION {
        info!(
            log,
            "Latest schema version: {}",
            CURRENT_SCHEMA_VERSION.as_u64(),
        );
    }

    Ok(())
}

#[derive(Debug, EnumString, EnumVariantNames)]
pub enum InspectTarget {
    #[strum(serialize = "sizes")]
    ValueSizes,
    #[strum(serialize = "total")]
    ValueTotal,
}

pub struct InspectConfig {
    column: DBColumn,
    target: InspectTarget,
}

fn parse_inspect_config(cli_args: &ArgMatches) -> Result<InspectConfig, String> {
    let column = clap_utils::parse_required(cli_args, "column")?;
    let target = clap_utils::parse_required(cli_args, "output")?;

    Ok(InspectConfig { column, target })
}

pub fn inspect_db<E: EthSpec>(
    inspect_config: InspectConfig,
    client_config: ClientConfig,
    runtime_context: &RuntimeContext<E>,
    log: Logger,
) -> Result<(), Error> {
    let spec = runtime_context.eth2_config.spec.clone();
    let hot_path = client_config.get_db_path();
    let cold_path = client_config.get_freezer_db_path();

    let db = HotColdDB::<E, LevelDB<E>, LevelDB<E>>::open(
        &hot_path,
        &cold_path,
        |_, _, _| Ok(()),
        client_config.store,
        spec,
        log,
    )?;

    let mut total = 0;

    for res in db.hot_db.iter_column(inspect_config.column) {
        let (key, value) = res?;

        match inspect_config.target {
            InspectTarget::ValueSizes => {
                println!("{:?}: {} bytes", key, value.len());
                total += value.len();
            }
            InspectTarget::ValueTotal => {
                total += value.len();
            }
        }
    }

    match inspect_config.target {
        InspectTarget::ValueSizes | InspectTarget::ValueTotal => {
            println!("Total: {} bytes", total);
        }
    }

    Ok(())
}

pub struct MigrateConfig {
    to: SchemaVersion,
}

fn parse_migrate_config(cli_args: &ArgMatches) -> Result<MigrateConfig, String> {
    let to = SchemaVersion(clap_utils::parse_required(cli_args, "to")?);

    Ok(MigrateConfig { to })
}

pub fn migrate_db<E: EthSpec>(
    migrate_config: MigrateConfig,
    client_config: ClientConfig,
    runtime_context: &RuntimeContext<E>,
    log: Logger,
) -> Result<(), Error> {
    let spec = runtime_context.eth2_config.spec.clone();
    let hot_path = client_config.get_db_path();
    let cold_path = client_config.get_freezer_db_path();

    let mut from = CURRENT_SCHEMA_VERSION;
    let to = migrate_config.to;
    let db = HotColdDB::<E, LevelDB<E>, LevelDB<E>>::open(
        &hot_path,
        &cold_path,
        |_, db_initial_version, _| {
            from = db_initial_version;
            Ok(())
        },
        client_config.store.clone(),
        spec,
        log.clone(),
    )?;

    info!(
        log,
        "Migrating database schema";
        "from" => from.as_u64(),
        "to" => to.as_u64(),
    );

    migrate_schema::<Witness<SystemTimeSlotClock, CachingEth1Backend<E>, _, _, _>>(
        db,
        &client_config.get_data_dir(),
        from,
        to,
        log,
    )
}

/// Run the database manager, returning an error string if the operation did not succeed.
pub fn run<T: EthSpec>(cli_args: &ArgMatches<'_>, mut env: Environment<T>) -> Result<(), String> {
    let client_config = parse_client_config(cli_args, &env)?;
    let context = env.core_context();
    let log = context.log().clone();

    match cli_args.subcommand() {
        ("version", Some(_)) => display_db_version(client_config, &context, log),
        ("migrate", Some(cli_args)) => {
            let migrate_config = parse_migrate_config(cli_args)?;
            migrate_db(migrate_config, client_config, &context, log)
        }
        ("inspect", Some(cli_args)) => {
            let inspect_config = parse_inspect_config(cli_args)?;
            inspect_db(inspect_config, client_config, &context, log)
        }
        _ => {
            return Err("Unknown subcommand, for help `lighthouse database_manager --help`".into())
        }
    }
    .map_err(|e| format!("Fatal error: {:?}", e))
}