use near_contract_standards::fungible_token::metadata::{
    FungibleTokenMetadata, FungibleTokenMetadataProvider, FT_METADATA_SPEC,
};
use near_contract_standards::fungible_token::{
    FungibleToken, FungibleTokenCore, FungibleTokenResolver,
};
use near_contract_standards::storage_management::{
    StorageBalance, StorageBalanceBounds, StorageManagement,
};
use near_sdk::borsh::BorshSerialize;
use near_sdk::collections::LazyOption;
use near_sdk::json_types::U128;
use near_sdk::{
    env, log, near, require, AccountId, BorshStorageKey, NearToken, PanicOnDefault, PromiseOrValue,
};

#[derive(PanicOnDefault)]
#[near(contract_state)]
pub struct Contract {
    token: FungibleToken,
    metadata: LazyOption<FungibleTokenMetadata>,
}

#[derive(BorshSerialize, BorshStorageKey)]
#[borsh(crate = "near_sdk::borsh")]
enum StorageKey {
    FungibleToken,
    Metadata,
}

#[near]
impl Contract {
    /// Initializes the contract with the given total supply owned by the given `owner_id` with
    /// default metadata (for example purposes only).
    #[init]
    pub fn new_default_meta(
        owner_id: AccountId,
        total_supply: U128,
        symbol: String,
        decimals: u8,
    ) -> Self {
        Self::new(
            owner_id,
            total_supply,
            FungibleTokenMetadata {
                spec: FT_METADATA_SPEC.to_string(),
                name: symbol.clone(),
                symbol,
                icon: None,
                reference: None,
                reference_hash: None,
                decimals,
            },
        )
    }

    /// Initializes the contract with the given total supply owned by the given `owner_id` with
    /// the given fungible token metadata.
    #[init]
    pub fn new(owner_id: AccountId, total_supply: U128, metadata: FungibleTokenMetadata) -> Self {
        require!(!env::state_exists(), "Already initialized");
        metadata.assert_valid();
        let mut this = Self {
            token: FungibleToken::new(StorageKey::FungibleToken),
            metadata: LazyOption::new(StorageKey::Metadata, Some(&metadata)),
        };
        this.token.internal_register_account(&owner_id);
        this.token.internal_deposit(&owner_id, total_supply.into());

        near_contract_standards::fungible_token::events::FtMint {
            owner_id: &owner_id,
            amount: total_supply,
            memo: Some("new tokens are minted"),
        }
        .emit();

        this
    }
}

#[near]
impl FungibleTokenCore for Contract {
    #[payable]
    fn ft_transfer(&mut self, receiver_id: AccountId, amount: U128, memo: Option<String>) {
        self.token.ft_transfer(receiver_id, amount, memo)
    }

    #[payable]
    fn ft_transfer_call(
        &mut self,
        receiver_id: AccountId,
        amount: U128,
        memo: Option<String>,
        msg: String,
    ) -> PromiseOrValue<U128> {
        self.token.ft_transfer_call(receiver_id, amount, memo, msg)
    }

    fn ft_total_supply(&self) -> U128 {
        self.token.ft_total_supply()
    }

    fn ft_balance_of(&self, account_id: AccountId) -> U128 {
        self.token.ft_balance_of(account_id)
    }
}

#[near]
impl FungibleTokenResolver for Contract {
    #[private]
    fn ft_resolve_transfer(
        &mut self,
        sender_id: AccountId,
        receiver_id: AccountId,
        amount: U128,
    ) -> U128 {
        let (used_amount, burned_amount) =
            self.token
                .internal_ft_resolve_transfer(&sender_id, receiver_id, amount);
        if burned_amount > 0 {
            log!("Account @{} burned {}", sender_id, burned_amount);
        }
        used_amount.into()
    }
}

#[near]
impl StorageManagement for Contract {
    #[payable]
    fn storage_deposit(
        &mut self,
        account_id: Option<AccountId>,
        registration_only: Option<bool>,
    ) -> StorageBalance {
        self.token.storage_deposit(account_id, registration_only)
    }

    #[payable]
    fn storage_withdraw(&mut self, amount: Option<NearToken>) -> StorageBalance {
        self.token.storage_withdraw(amount)
    }

    #[payable]
    fn storage_unregister(&mut self, force: Option<bool>) -> bool {
        #[allow(unused_variables)]
        if let Some((account_id, balance)) = self.token.internal_storage_unregister(force) {
            log!("Closed @{} with {}", account_id, balance);
            true
        } else {
            false
        }
    }

    fn storage_balance_bounds(&self) -> StorageBalanceBounds {
        self.token.storage_balance_bounds()
    }

    fn storage_balance_of(&self, account_id: AccountId) -> Option<StorageBalance> {
        self.token.storage_balance_of(account_id)
    }
}

#[near]
impl FungibleTokenMetadataProvider for Contract {
    fn ft_metadata(&self) -> FungibleTokenMetadata {
        self.metadata.get().unwrap()
    }
}