NFTs

use near_contract_standards::non_fungible_token::metadata::{
    NFTContractMetadata, NonFungibleTokenMetadataProvider, TokenMetadata, NFT_METADATA_SPEC,
};
use near_contract_standards::non_fungible_token::{Token, TokenId};
use near_contract_standards::non_fungible_token::NonFungibleToken;
use near_sdk::borsh::{self, BorshDeserialize, BorshSerialize};
use near_sdk::collections::LazyOption;
use near_sdk::json_types::ValidAccountId;
use near_sdk::{
    env, near_bindgen, AccountId, BorshStorageKey, PanicOnDefault, Promise, PromiseOrValue,
};

near_sdk::setup_alloc!();

#[near_bindgen]
#[derive(BorshDeserialize, BorshSerialize, PanicOnDefault)]
pub struct Contract {
    tokens: NonFungibleToken,
    metadata: LazyOption<NFTContractMetadata>,
}

const DATA_IMAGE_SVG_NEAR_ICON: &str = "data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 288 288'%3E%3Cg id='l' data-name='l'%3E%3Cpath d='M187.58,79.81l-30.1,44.69a3.2,3.2,0,0,0,4.75,4.2L191.86,103a1.2,1.2,0,0,1,2,.91v80.46a1.2,1.2,0,0,1-2.12.77L102.18,77.93A15.35,15.35,0,0,0,90.47,72.5H87.34A15.34,15.34,0,0,0,72,87.84V201.16A15.34,15.34,0,0,0,87.34,216.5h0a15.35,15.35,0,0,0,13.08-7.31l30.1-44.69a3.2,3.2,0,0,0-4.75-4.2L96.14,186a1.2,1.2,0,0,1-2-.91V104.61a1.2,1.2,0,0,1,2.12-.77l89.55,107.23a15.35,15.35,0,0,0,11.71,5.43h3.13A15.34,15.34,0,0,0,216,201.16V87.84A15.34,15.34,0,0,0,200.66,72.5h0A15.35,15.35,0,0,0,187.58,79.81Z'/%3E%3C/g%3E%3C/svg%3E";

#[derive(BorshSerialize, BorshStorageKey)]
enum StorageKey {
    NonFungibleToken,
    Metadata,
    TokenMetadata,
    Enumeration,
    Approval,
}

#[near_bindgen]
impl Contract {
    /// Initializes the contract owned by `owner_id` with
    /// default metadata (for example purposes only).
    #[init]
    pub fn new_default_meta(owner_id: ValidAccountId) -> Self {
        Self::new(
            owner_id,
            NFTContractMetadata {
                spec: NFT_METADATA_SPEC.to_string(),
                name: "Example NEAR non-fungible token".to_string(),
                symbol: "EXAMPLE".to_string(),
                icon: Some(DATA_IMAGE_SVG_NEAR_ICON.to_string()),
                base_uri: None,
                reference: None,
                reference_hash: None,
            },
        )
    }

    #[init]
    pub fn new(owner_id: ValidAccountId, metadata: NFTContractMetadata) -> Self {
        assert!(!env::state_exists(), "Already initialized");
        metadata.assert_valid();
        Self {
            tokens: NonFungibleToken::new(
                StorageKey::NonFungibleToken,
                owner_id,
                Some(StorageKey::TokenMetadata),
                Some(StorageKey::Enumeration),
                Some(StorageKey::Approval),
            ),
            metadata: LazyOption::new(StorageKey::Metadata, Some(&metadata)),
        }
    }

    #[payable]
    pub fn nft_mint(
        &mut self,
        token_id: TokenId,
        receiver_id: ValidAccountId,
        token_metadata: TokenMetadata,
    ) -> Token {
        self.tokens.mint(token_id, receiver_id, Some(token_metadata))
    }
}

near_contract_standards::impl_non_fungible_token_core!(Contract, tokens);
near_contract_standards::impl_non_fungible_token_approval!(Contract, tokens);
near_contract_standards::impl_non_fungible_token_enumeration!(Contract, tokens);

#[near_bindgen]
impl NonFungibleTokenMetadataProvider for Contract {
    fn nft_metadata(&self) -> NFTContractMetadata {
        self.metadata.get().unwrap()
    }
}

pub struct TokenMetadata {
    pub title: Option<String>, // ex. "Arch Nemesis: Mail Carrier" or "Parcel #5055"
    pub description: Option<String>, // free-form description
    pub media: Option<String>, // URL to associated media, preferably to decentralized, content-addressed storage
    pub media_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of content referenced by the `media` field. Required if `media` is included.
    pub copies: Option<u64>, // number of copies of this set of metadata in existence when token was minted.
    pub issued_at: Option<String>, // ISO 8601 datetime when token was issued or minted
    pub expires_at: Option<String>, // ISO 8601 datetime when token expires
    pub starts_at: Option<String>, // ISO 8601 datetime when token starts being valid
    pub updated_at: Option<String>, // ISO 8601 datetime when token was last updated
    pub extra: Option<String>, // anything extra the NFT wants to store on-chain. Can be stringified JSON.
    pub reference: Option<String>, // URL to an off-chain JSON file with more info.
    pub reference_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
}