import { PublicKey } from "@solana/web3.js";
import { PROGRAM_ID } from "../constants.js";

/**
 * User profile state structure
 */
export interface UserProfile {
  owner: PublicKey;
  nickname: string;
  bump: number;
}

/**
 * Derive the user profile PDA for a wallet
 *
 * @param wallet - User's wallet public key
 * @returns User profile PDA public key
 *
 * @example
 * ```typescript
 * const profilePda = getUserProfileAddress(wallet.publicKey);
 * const accountInfo = await connection.getAccountInfo(profilePda);
 * ```
 */
export function getUserProfileAddress(wallet: PublicKey): PublicKey {
  const [pda] = PublicKey.findProgramAddressSync(
    [Buffer.from("user_profile"), wallet.toBuffer()],
    PROGRAM_ID
  );
  return pda;
}

/**
 * Derive the user profile PDA with bump
 *
 * @param wallet - User's wallet public key
 * @returns Tuple of [PDA, bump]
 */
export function getUserProfileAddressWithBump(wallet: PublicKey): [PublicKey, number] {
  return PublicKey.findProgramAddressSync(
    [Buffer.from("user_profile"), wallet.toBuffer()],
    PROGRAM_ID
  );
}

/**
 * Parse a UserProfile account from raw buffer data
 *
 * @param data - Raw account data buffer (excluding 8-byte discriminator)
 * @returns Parsed UserProfile object
 * @throws Error if buffer is too small
 *
 * @example
 * ```typescript
 * const profilePda = getUserProfileAddress(wallet);
 * const accountInfo = await connection.getAccountInfo(profilePda);
 * if (accountInfo) {
 *   const profile = parseUserProfileAccount(accountInfo.data.slice(8));
 * }
 * ```
 */
export function parseUserProfileAccount(data: Uint8Array): UserProfile {
  const buffer = Buffer.from(data);
  const MIN_SIZE = 32 + 4 + 1; // owner + string length + bump

  if (buffer.length < MIN_SIZE) {
    throw new Error(
      `Buffer too small for UserProfile: expected at least ${MIN_SIZE} bytes, got ${buffer.length}`
    );
  }

  let offset = 0;

  // owner: Pubkey (32 bytes)
  const owner = new PublicKey(buffer.slice(offset, offset + 32));
  offset += 32;

  // nickname: String (4-byte length prefix + UTF-8 bytes)
  const nicknameLength = buffer.readUInt32LE(offset);
  offset += 4;
  const nickname = buffer.slice(offset, offset + nicknameLength).toString("utf-8");
  offset += nicknameLength;

  // bump: u8
  const bump = buffer.readUInt8(offset);

  return {
    owner,
    nickname,
    bump,
  };
}