import {
  PublicKey,
  TransactionInstruction,
  SystemProgram,
  SYSVAR_RENT_PUBKEY,
} from "@solana/web3.js";
import BN from "bn.js";
import { ASSOCIATED_TOKEN_PROGRAM_ID, TOKEN_PROGRAM_ID } from "@solana/spl-token";
import type { PitProgram } from "../program.js";
import { WSOL_MINT, TOKEN_2022_PROGRAM_ID } from "../constants.js";
import { getMarketAddress, getWsolVaultAddress, getRegistryAddress } from "../accounts/pda.js";

/**
 * Parameters for creating an initialize_market instruction
 *
 * This merged instruction creates a complete market with both High and Low pools
 * in a single transaction.
 */
interface InitializeMarketParams {
  /** Week number for this market (unique identifier) */
  weekNumber: number;
  /** Unix timestamp when the market ends */
  endTimestamp: BN;
  /** Total subsidy in lamports (SOL to seed liquidity, split 50/50 between pools) */
  totalSubsidy: BN;
  /** Operator's public key (must match hardcoded OPERATOR) */
  operator: PublicKey;
  /** Pyth price update account for SOL/USD */
  priceUpdate: PublicKey;
  /** Initial q_vector for High pool [S0, S1, S2, S3] - values in WAD format (10^18) */
  highQVector: [BN, BN, BN, BN];
  /** Initial q_vector for Low pool [S0, S1, S2, S3] - values in WAD format (10^18) */
  lowQVector: [BN, BN, BN, BN];
  /**
   * All 12 mint accounts in order:
   * - [0-2]: High pool HIT mints (strike 0, 1, 2)
   * - [3-5]: High pool MISS mints (strike 0, 1, 2)
   * - [6-8]: Low pool HIT mints (strike 0, 1, 2)
   * - [9-11]: Low pool MISS mints (strike 0, 1, 2)
   */
  mints: PublicKey[];
  /** wSOL mint address (usually WSOL_MINT constant) */
  wsolMint?: PublicKey;
}

/**
 * Create an initialize_market instruction
 *
 * This instruction is operator-only. It creates a complete market with both
 * High and Low pools, initializes all 12 token mints with metadata, transfers
 * the subsidy, and registers the market in the global registry.
 *
 * Strikes are automatically calculated on-chain from the current Pyth SOL/USD price.
 *
 * @param program - Anchor Program instance
 * @param params - Initialize market parameters
 * @returns Promise resolving to TransactionInstruction
 *
 * @example
 * ```typescript
 * import { createProgram, createInitializeMarketInstruction, createZeroQVector, getAllMintAddresses } from "@pit-protocol/sdk";
 *
 * const program = createProgram(provider);
 *
 * // First, create 12 Token-2022 mints with MetadataPointer extension
 * const mints = getAllMintAddresses(2604);
 *
 * // Get Pyth price update account
 * const priceUpdate = SOL_USD_PRICE_FEED_ACCOUNT;
 *
 * // Create the instruction
 * const ix = await createInitializeMarketInstruction(program, {
 *   weekNumber: 2604,
 *   endTimestamp: new BN(Math.floor(Date.now() / 1000) + 7 * 24 * 60 * 60),
 *   totalSubsidy: new BN(10 * LAMPORTS_PER_SOL),
 *   operator: operatorKeypair.publicKey,
 *   priceUpdate,
 *   highQVector: createZeroQVector(),
 *   lowQVector: createZeroQVector(),
 *   mints,
 * });
 *
 * const tx = new Transaction().add(ix);
 * await sendAndConfirmTransaction(connection, tx, [operatorKeypair]);
 * ```
 */
export async function createInitializeMarketInstruction(
  program: PitProgram,
  params: InitializeMarketParams
): Promise<TransactionInstruction> {
  const {
    weekNumber,
    endTimestamp,
    totalSubsidy,
    operator,
    priceUpdate,
    highQVector,
    lowQVector,
    mints,
    wsolMint = WSOL_MINT,
  } = params;

  // Validate mints count
  if (mints.length !== 12) {
    throw new Error(`Expected 12 mints, got ${mints.length}`);
  }

  const marketState = getMarketAddress(weekNumber);
  const wsolVault = getWsolVaultAddress(marketState, wsolMint);
  const registry = getRegistryAddress();

  // Convert q_vectors to array format expected by Anchor
  const highQVectorArg = highQVector.map((q) => q);
  const lowQVectorArg = lowQVector.map((q) => q);

  return await program.methods
    .initializeMarket(weekNumber, endTimestamp, totalSubsidy, highQVectorArg, lowQVectorArg)
    .accountsPartial({
      marketState,
      operator,
      wsolMint,
      wsolVault,
      registry,
      priceUpdate,
      systemProgram: SystemProgram.programId,
      tokenProgram: TOKEN_PROGRAM_ID,
      associatedTokenProgram: ASSOCIATED_TOKEN_PROGRAM_ID,
      token2022Program: TOKEN_2022_PROGRAM_ID,
      rent: SYSVAR_RENT_PUBKEY,
    })
    .remainingAccounts(
      mints.map((mint) => ({
        pubkey: mint,
        isSigner: false,
        isWritable: true,
      }))
    )
    .instruction();
}

/**
 * Helper to create zero q_vector (equal probability for all outcomes).
 * All outcomes start at 25% probability.
 */
export function createZeroQVector(): [BN, BN, BN, BN] {
  return [new BN(0), new BN(0), new BN(0), new BN(0)];
}