Metadata & Metadata Pointer Extensions

use anyhow::Result;
use solana_client::nonblocking::rpc_client::RpcClient;
use solana_commitment_config::CommitmentConfig;
use solana_sdk::{
    signature::{Keypair, Signer},
    transaction::Transaction,
};
use solana_system_interface::instruction::create_account;
use spl_token_2022_interface::{
    extension::{
        metadata_pointer::{
            instruction::initialize as initialize_metadata_pointer, MetadataPointer,
        },
        BaseStateWithExtensions, ExtensionType, StateWithExtensions,
    },
    instruction::initialize_mint,
    state::Mint,
    ID as TOKEN_2022_PROGRAM_ID,
};
use spl_token_metadata_interface::{
    instruction::{initialize as initialize_token_metadata, update_field},
    state::{Field, TokenMetadata},
};

#[tokio::main]
async fn main() -> Result<()> {
    // Create connection to local validator
    let client = RpcClient::new_with_commitment(
        String::from("http://localhost:8899"),
        CommitmentConfig::confirmed(),
    );
    let latest_blockhash = client.get_latest_blockhash().await?;

    // Generate a new keypair for the fee payer
    let fee_payer = Keypair::new();

    // Airdrop 5 SOL to fee payer
    let airdrop_signature = client
        .request_airdrop(&fee_payer.pubkey(), 5_000_000_000)
        .await?;

    loop {
        let confirmed = client.confirm_transaction(&airdrop_signature).await?;
        if confirmed {
            break;
        }
    }

    // Generate keypair for the mint
    let mint = Keypair::new();

    // Define Token metadata
    let token_metadata  = TokenMetadata {
        update_authority: Some(fee_payer.pubkey()).try_into()?,
        mint: mint.pubkey(),
        name: "OPOS".to_string(),
        symbol : "OPS".to_string(),
        uri : "https://raw.githubusercontent.com/solana-developers/opos-asset/main/assets/DeveloperPortal/metadata.json".to_string(),
        additional_metadata: vec![("description".to_string(),"only possible on Solana".to_string())]
    };

    // Calculate space for mint with metadata pointer and token metadata extensions
    let mint_space =
        ExtensionType::try_calculate_account_len::<Mint>(&[ExtensionType::MetadataPointer])?;

    let metadata_len = token_metadata.tlv_size_of()?;

    let mint_rent = client
        .get_minimum_balance_for_rent_exemption(mint_space + metadata_len)
        .await?;

    // Instruction to create new account for mint (token22)
    let create_mint_account_instruction = create_account(
        &fee_payer.pubkey(),    // payer
        &mint.pubkey(),         // new account (mint)
        mint_rent,              // lamports
        mint_space as u64,      // space
        &TOKEN_2022_PROGRAM_ID, // program id
    );

    // Instruction to initialize metadata pointer (pointing to itself for self-managed metadata)
    let initialize_metadata_pointer_instruction = initialize_metadata_pointer(
        &TOKEN_2022_PROGRAM_ID,
        &mint.pubkey(),
        Some(fee_payer.pubkey()), // authority
        Some(mint.pubkey()),      // metadata address (pointing to self)
    )?;

    // Instruction to initialize mint account data
    let initialize_mint_instruction = initialize_mint(
        &TOKEN_2022_PROGRAM_ID,    // program id
        &mint.pubkey(),            // mint
        &fee_payer.pubkey(),       // mint authority
        Some(&fee_payer.pubkey()), // freeze authority
        9,                         // decimals
    )?;

    // Instruction to initialize token metadata
    let initialize_metadata_instruction = initialize_token_metadata(
        &TOKEN_2022_PROGRAM_ID,            // program id
        &mint.pubkey(),                    //metadata
        &fee_payer.pubkey(),               // update authority
        &mint.pubkey(),                    // mint
        &fee_payer.pubkey(),               // mint authority
        token_metadata.name.to_string(),   // name
        token_metadata.symbol.to_string(), // symbol
        token_metadata.uri.to_string(),    // uri
    );

    // Create update field instructions from token_metadata.additional_metadata
    // Additional metadata must be initialized separately using the update_field instruction
    // If the field already exists, it will be updated instead of creating a new field
    let update_field_instructions: Vec<_> = token_metadata
        .additional_metadata
        .iter()
        .map(|(key, value)| {
            update_field(
                &TOKEN_2022_PROGRAM_ID,
                &mint.pubkey(),
                &fee_payer.pubkey(),
                Field::Key(key.clone()),
                value.clone(),
            )
        })
        .collect();

    // Construct transaction with all instructions
    let mut instructions = vec![
        create_mint_account_instruction,
        initialize_metadata_pointer_instruction,
        initialize_mint_instruction,
        initialize_metadata_instruction,
    ];
    instructions.extend(update_field_instructions);

    let transaction = Transaction::new_signed_with_payer(
        &instructions,
        Some(&fee_payer.pubkey()),
        &[&fee_payer, &mint],
        latest_blockhash,
    );

    let transaction_signature = client.send_and_confirm_transaction(&transaction).await?;

    println!("Mint Address: {}", mint.pubkey());
    println!("Transaction Signature: {}", transaction_signature);

    // Fetch mint account
    let mint_account = client.get_account(&mint.pubkey()).await?;
    // Deserialize the mint account with extensions
    let mint_state = StateWithExtensions::<Mint>::unpack(&mint_account.data)?;

    // Get all extension types enabled on this mint
    let extension_types = mint_state.get_extension_types()?;
    println!("\nExtensions enabled: {:?}", extension_types);

    // Deserialize the MetadataPointer extension data
    let metadata_pointer = mint_state.get_extension::<MetadataPointer>()?;
    println!("\n{:#?}", metadata_pointer);

    // Deserialize the TokenMetadata extension data (variable-length)
    let token_metadata = mint_state.get_variable_len_extension::<TokenMetadata>()?;
    println!("\n{:#?}", token_metadata);

    Ok(())
}