Add metadata to nft-simple (#137)

* nft-simple: add metadata for token and contract, for init and minting fns, and nft_metadata fn

* update nft_simple WASM file

nft-simple/src/lib.rs

@@ -2,17 +2,19 @@ use std::collections::HashSet;
 
 use near_sdk::borsh::{self, BorshDeserialize, BorshSerialize};
 use near_sdk::collections::{LookupMap, UnorderedMap, UnorderedSet};
-use near_sdk::json_types::ValidAccountId;
+use near_sdk::json_types::{ValidAccountId, Base64VecU8, U64};
 use near_sdk::serde::{Deserialize, Serialize};
 use near_sdk::{env, near_bindgen, AccountId, Balance, PanicOnDefault, Promise, StorageUsage};
 
 use crate::internal::*;
 pub use crate::mint::*;
 pub use crate::nft_core::*;
+use crate::nft_metadata::{TokenMetadata, NFTMetadata};
 
 mod internal;
 mod mint;
 mod nft_core;
+mod nft_metadata;
 
 #[global_allocator]
 static ALLOC: near_sdk::wee_alloc::WeeAlloc<'_> = near_sdk::wee_alloc::WeeAlloc::INIT;
@@ -23,7 +25,7 @@ pub type TokenId = String;
 #[serde(crate = "near_sdk::serde")]
 pub struct Token {
     pub owner_id: AccountId,
-    pub metadata: String,
+    pub metadata: TokenMetadata,
     pub approved_account_ids: HashSet<AccountId>,
 }
 
@@ -38,18 +40,21 @@ pub struct Contract {
 
     /// The storage size in bytes for one account.
     pub extra_storage_in_bytes_per_token: StorageUsage,
+
+    pub metadata: NFTMetadata
 }
 
 #[near_bindgen]
 impl Contract {
     #[init]
-    pub fn new(owner_id: ValidAccountId) -> Self {
+    pub fn new(owner_id: ValidAccountId, metadata: NFTMetadata) -> Self {
         assert!(!env::state_exists(), "Already initialized");
         let mut this = Self {
             tokens_per_owner: LookupMap::new(b"a".to_vec()),
             tokens_by_id: UnorderedMap::new(b"t".to_vec()),
             owner_id: owner_id.into(),
             extra_storage_in_bytes_per_token: 0,
+            metadata
         };
 
         this.measure_min_token_storage_cost();

nft-simple/src/mint.rs

@@ -3,7 +3,7 @@ use crate::*;
 #[near_bindgen]
 impl Contract {
     #[payable]
-    pub fn nft_mint(&mut self, token_id: TokenId, metadata: String) {
+    pub fn nft_mint(&mut self, token_id: TokenId, metadata: TokenMetadata) {
         let initial_storage_usage = env::storage_usage();
         self.assert_owner();
         let token = Token {

nft-simple/src/nft_metadata.rs

@@ -0,0 +1,41 @@
+use crate::*;
+
+#[derive(BorshDeserialize, BorshSerialize, Serialize, Deserialize, Clone)]
+#[serde(crate = "near_sdk::serde")]
+pub struct NFTMetadata {
+    spec: String, // required, essentially a version like "nft-1.0.0"
+    name: String, // required, ex. "Mosaics"
+    symbol: String, // required, ex. "MOSIAC"
+    icon: Option<String>, // Data URL
+    base_uri: Option<String>, // Centralized gateway known to have reliable access to decentralized storage assets referenced by `reference` or `media` URLs
+    reference: Option<String>, // URL to a JSON file with more info
+    reference_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
+}
+
+#[derive(BorshDeserialize, BorshSerialize, Serialize, Deserialize)]
+#[serde(crate = "near_sdk::serde")]
+pub struct TokenMetadata {
+    title: Option<String>, // ex. "Arch Nemesis: Mail Carrier" or "Parcel #5055"
+    description: Option<String>, // free-form description
+    media: Option<String>, // URL to associated media, preferably to decentralized, content-addressed storage
+    media_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of content referenced by the `media` field. Required if `media` is included.
+    copies: Option<U64>, // number of copies of this set of metadata in existence when token was minted.
+    issued_at: Option<String>, // ISO 8601 datetime when token was issued or minted
+    expires_at: Option<String>, // ISO 8601 datetime when token expires
+    starts_at: Option<String>, // ISO 8601 datetime when token starts being valid
+    updated_at: Option<String>, // ISO 8601 datetime when token was last updated
+    extra: Option<String>, // anything extra the NFT wants to store on-chain. Can be stringified JSON.
+    reference: Option<String>, // URL to an off-chain JSON file with more info.
+    reference_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
+}
+
+pub trait NonFungibleTokenMetadata {
+    fn nft_metadata(&self) -> NFTMetadata;
+}
+
+#[near_bindgen]
+impl NonFungibleTokenMetadata for Contract {
+    fn nft_metadata(&self) -> NFTMetadata {
+        self.metadata.clone()
+    }
+}