// Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0

// Copyright 2021 Conflux Foundation. All rights reserved.
// Conflux is free software and distributed under GNU General Public License.
// See http://www.gnu.org/licenses/

use crate::account_config::constants::CORE_CODE_ADDRESS;
use anyhow::{bail, Result};
use move_core_types::{
    identifier::Identifier,
    language_storage::{ModuleId, StructTag, TypeTag},
};
use once_cell::sync::Lazy;

pub const DIEM_MODULE_NAME: &str = "Diem";
static COIN_MODULE_NAME: Lazy<Identifier> =
    Lazy::new(|| Identifier::new("Diem").unwrap());
pub static COIN_MODULE: Lazy<ModuleId> =
    Lazy::new(|| ModuleId::new(CORE_CODE_ADDRESS, COIN_MODULE_NAME.clone()));

// TODO: This imposes a few implied restrictions:
//   1) The currency module must be published under the core code address.
//   2) The module name must be the same as the gas specifier.
//   3) The struct name must be the same as the module name
// We need to consider whether we want to switch to a more or fully qualified
// name.
pub fn type_tag_for_currency_code(currency_code: Identifier) -> TypeTag {
    TypeTag::Struct(StructTag {
        address: CORE_CODE_ADDRESS,
        module: currency_code.clone(),
        name: currency_code,
        type_params: vec![],
    })
}

/// In addition to the constraints for valid Move identifiers, currency codes
/// should consist entirely of uppercase alphanumeric characters (e.g., no
/// underscores).
pub fn allowed_currency_code_string(
    possible_currency_code_string: &str,
) -> bool {
    possible_currency_code_string
        .chars()
        .all(|chr| matches!(chr, 'A'..='Z' | '0'..='9'))
        && Identifier::is_valid(possible_currency_code_string)
}

pub fn from_currency_code_string(
    currency_code_string: &str,
) -> Result<Identifier> {
    if !allowed_currency_code_string(currency_code_string) {
        bail!("Invalid currency code '{}'", currency_code_string)
    }
    Identifier::new(currency_code_string)
}