import { struct, u8 } from '@solana/buffer-layout';
import type { AccountMeta, PublicKey } from '@solana/web3.js';
import { TransactionInstruction } from '@solana/web3.js';
import { programSupportsExtensions } from '../constants.js';
import {
    TokenInvalidInstructionDataError,
    TokenInvalidInstructionKeysError,
    TokenInvalidInstructionProgramError,
    TokenInvalidInstructionTypeError,
    TokenUnsupportedInstructionError,
} from '../errors.js';
import { TokenInstruction } from './types.js';
import { COptionPublicKeyLayout } from '../serialization.js';

/** TODO: docs */
export interface InitializeMintCloseAuthorityInstructionData {
    instruction: TokenInstruction.InitializeMintCloseAuthority;
    closeAuthority: PublicKey | null;
}

/** TODO: docs */
export const initializeMintCloseAuthorityInstructionData = struct<InitializeMintCloseAuthorityInstructionData>([
    u8('instruction'),
    new COptionPublicKeyLayout('closeAuthority'),
]);

/**
 * Construct an InitializeMintCloseAuthority instruction
 *
 * @param mint            Token mint account
 * @param closeAuthority  Optional authority that can close the mint
 * @param programId       SPL Token program account
 *
 * @return Instruction to add to a transaction
 */
export function createInitializeMintCloseAuthorityInstruction(
    mint: PublicKey,
    closeAuthority: PublicKey | null,
    programId: PublicKey,
): TransactionInstruction {
    if (!programSupportsExtensions(programId)) {
        throw new TokenUnsupportedInstructionError();
    }
    const keys = [{ pubkey: mint, isSigner: false, isWritable: true }];

    const data = Buffer.alloc(34); // worst-case size
    initializeMintCloseAuthorityInstructionData.encode(
        {
            instruction: TokenInstruction.InitializeMintCloseAuthority,
            closeAuthority,
        },
        data,
    );

    return new TransactionInstruction({
        keys,
        programId,
        data: data.subarray(0, initializeMintCloseAuthorityInstructionData.getSpan(data)),
    });
}

/** A decoded, valid InitializeMintCloseAuthority instruction */
export interface DecodedInitializeMintCloseAuthorityInstruction {
    programId: PublicKey;
    keys: {
        mint: AccountMeta;
    };
    data: {
        instruction: TokenInstruction.InitializeMintCloseAuthority;
        closeAuthority: PublicKey | null;
    };
}

/**
 * Decode an InitializeMintCloseAuthority instruction and validate it
 *
 * @param instruction Transaction instruction to decode
 * @param programId   SPL Token program account
 *
 * @return Decoded, valid instruction
 */
export function decodeInitializeMintCloseAuthorityInstruction(
    instruction: TransactionInstruction,
    programId: PublicKey,
): DecodedInitializeMintCloseAuthorityInstruction {
    if (!instruction.programId.equals(programId)) throw new TokenInvalidInstructionProgramError();
    if (instruction.data.length !== initializeMintCloseAuthorityInstructionData.getSpan(instruction.data))
        throw new TokenInvalidInstructionDataError();

    const {
        keys: { mint },
        data,
    } = decodeInitializeMintCloseAuthorityInstructionUnchecked(instruction);
    if (data.instruction !== TokenInstruction.InitializeMintCloseAuthority)
        throw new TokenInvalidInstructionTypeError();
    if (!mint) throw new TokenInvalidInstructionKeysError();

    return {
        programId,
        keys: {
            mint,
        },
        data,
    };
}

/** A decoded, non-validated InitializeMintCloseAuthority instruction */
export interface DecodedInitializeMintCloseAuthorityInstructionUnchecked {
    programId: PublicKey;
    keys: {
        mint: AccountMeta | undefined;
    };
    data: {
        instruction: number;
        closeAuthority: PublicKey | null;
    };
}

/**
 * Decode an InitializeMintCloseAuthority instruction without validating it
 *
 * @param instruction Transaction instruction to decode
 *
 * @return Decoded, non-validated instruction
 */
export function decodeInitializeMintCloseAuthorityInstructionUnchecked({
    programId,
    keys: [mint],
    data,
}: TransactionInstruction): DecodedInitializeMintCloseAuthorityInstructionUnchecked {
    const { instruction, closeAuthority } = initializeMintCloseAuthorityInstructionData.decode(data);

    return {
        programId,
        keys: {
            mint,
        },
        data: {
            instruction,
            closeAuthority,
        },
    };
}