declare module "node-lmdb" {
    type Key = string | number | Buffer;
    type Value = string | number | Buffer | boolean;

    type KeyType =
        | {
            /** if true, keys are treated as 32-bit unsigned integers */
            keyIsUint32?: boolean;
        }
        | {
            /** if true, keys are treated as Buffers */
            keyIsBuffer?: boolean;
        }
        | {
            /** if true, keys are treated as strings */
            keyIsString?: boolean;
        };

    type PutOptions = {
        noDupData?: boolean;
        noOverwrite?: boolean;
        append?: boolean;
        appendDup?: boolean;
    } & KeyType;

    interface Stat {
        pageSize: number;
        treeDepth: number;
        treeBranchPageCount: number;
        treeLeafPageCount: number;
        entryCount: number;
        overflowPages: number;
    }

    interface Info {
        mapAddress: number;
        mapSize: number;
        lastPageNumber: number;
        lastTxnId: number;
        maxReaders: number;
        numReaders: number;
    }


    type CursorCallback<T> = (k: Key, v: T) => void;

    enum BatchResult {
        SUCCESS = 0,
        CONDITION_NOT_MET = 1,
        NOT_FOUND = 2,
    }

    /**
     * Object argument for Env.batchWrite()
     */
    interface BatchOperation {
        /** the database instance to target for the operation */
        db: Dbi;
        /** the key to target for the operation */
        key: Key;
        /** If null, treat as a DELETE operation */
        value?: Value;
        /** If provided, ifValue must match the first X bytes of the stored value or the operation will be canceled */
        ifValue?: Value;
        /** If true, ifValue must match all bytes of the stored value or the operation will be canceled */
        ifExactMatch?: boolean;
        /** If provided, use this key to determine match for ifValue */
        ifKey?: Key;
        /** If provided, use this DB to determine match for ifValue */
        ifDB?: Dbi;
    }

    /**
     * Array argument for Env.batchWrite()
     * @example [db: Dbi, key: Key] // DELETE operation
     * @example [db: Dbi, key: Key, value: Value] // PUT operation
     * @example [db: Dbi, key: Key, value: Value, ifValue: Value] // PUT IF operation
     */
    type BatchOperationArray =
        | [db: Dbi, key: Key]
        | [db: Dbi, key: Key, value: Value]
        | [db: Dbi, key: Key, value: Value, ifValue: Value];

    /**
     * Options for opening a database instance
     */
    type DbiOptions = {
        /** the name of the database (or null to use the unnamed database) */
        name: string | null;
        /** if true, the database will be created if it doesn't exist */
        create?: boolean;
        /** keys are strings to be compared in reverse order */
        reverseKey?: boolean;
        /** if true, the database can hold multiple items with the same key */
        dupSort?: boolean;
        /** if dupSort is true, indicates that the data items are all the same size */
        dupFixed?: boolean;
        /** duplicate data items are also integers, and should be sorted as such */
        integerDup?: boolean;
        /** duplicate data items should be compared as strings in reverse order */
        reverseDup?: boolean;
        /** if a read/write transaction is currently open, pass it here */
        txn?: Txn;
    } & KeyType;

    interface EnvOptions {
        path?: string;
        mapSize?: number;
        maxDbs?: number;
        maxReaders?: number;
        noSubdir?: boolean;
        readOnly?: boolean;
        useWritemap?: boolean;
        usePreviousSnapshot?: boolean;
        noMemInit?: boolean;
        noReadAhead?: boolean;
        noMetaSync?: boolean;
        noSync?: boolean;
        mapAsync?: boolean;
        unsafeNoLock?: boolean;
    }

    interface TxnOptions {
        readOnly: boolean;
    }

    class Env {
        open(options: EnvOptions): void;

        /**
         * Open a database instance
         * @param {DbiOptions} options
         */
        openDbi(options: DbiOptions): Dbi;

        /**
         * Begin a transaction
         */
        beginTxn(options?: TxnOptions): Txn;

        /**
         * Detatch from the memory-mapped object retrieved with getStringUnsafe()
         * or getBinaryUnsafe(). This must be called after reading the object and
         * before it is accessed again, or V8 will crash.
         * @param buffer
         */
        detachBuffer(buffer: ArrayBufferLike): void;

        /**
         * Retrieve Environment statistics.
         */
        stat(): Stat;

        /**
         * Gets information about the database environment.
         */
        info(): Info;

        /**
         * Resizes the maximal size of the memory map. It may be called if no transactions are active in this process.
         * @param {number} size maximal size of the memory map (the full environment) in bytes (default is 10485760 bytes)
         */
        resize(size: number): void;

        /**
         * When `batchWrite` is called, `node-ldmb` will asynchronously create a
         * new write transaction, execute all the operations in the provided
         * array, except for any conditional writes where the condition failed,
         * and commit the transaction, if there were no errors. For conditional
         * writes, if the condition did not match, the write will be skipped,
         * but the transaction will still be committed. However, if any errors
         * occur, the transaction will be aborted. This entire transaction will
         * be created by `node-lmdb` and executed in a separate thread. The
         * callback function will be called once the transaction is finished. It
         * is possible for an explicit write transaction in the main JS thread
         * to block or be blocked by the asynchronous transaction.
         * @param {Array} operations
         * @param {object} options
         * @param {Function} options.progress callback function for reporting
         *                                    progress on a batch operation.
         * @param callback
         */
        batchWrite(
            operations: (BatchOperation | BatchOperationArray)[],
            options?: PutOptions & {
                progress?: (results: BatchResult[]) => void;
            },
            callback?: (err: Error, results: BatchResult[]) => void
        ): void;

        copy(
            path: string,
            compact?: boolean,
            callback?: (err: Error) => void
        ): void;

        /**
         * Close the environment
         */
        close(): void;
    }

    type DropOptions = { txn?: Txn; justFreePages: boolean };

    /**
     * Database Instance: represents a single K/V store.
     */
    type Dbi = {
        close(): void;
        drop(options?: DropOptions): void;
        stat(tx: Txn): Stat;
    };

    /**
     * Transaction (read-only or read-write)
     */
    type Txn = {
        getString(dbi: Dbi, key: Key, options?: KeyType): string;
        putString(dbi: Dbi, key: Key, value: string, options?: PutOptions): void;

        getBinary(dbi: Dbi, key: Key, options?: KeyType): Buffer;
        putBinary(dbi: Dbi, key: Key, value: Buffer, options?: PutOptions): void;

        getNumber(dbi: Dbi, key: Key, options?: KeyType): number;
        putNumber(dbi: Dbi, key: Key, value: number, options?: PutOptions): void;

        getBoolean(dbi: Dbi, key: Key, options?: KeyType): boolean;
        putBoolean(dbi: Dbi, key: Key, value: boolean, options?: PutOptions): void;

        del(dbi: Dbi, key: Key, options?: KeyType): void;

        /**
         * Retrieve a string using zero-copy semantics. Env.detachBuffer() must
         * be called on the underlying buffer after the data is accessed.
         */
        getStringUnsafe(dbi: Dbi, key: Key, options?: KeyType): string;

        /**
         * Retrieve a Buffer using zero-copy semantics. Env.detachBuffer() must
         * be called on the underlying buffer after the data is accessed.
         */
        getBinaryUnsafe(dbi: Dbi, key: Key, options?: KeyType): Buffer;

        /**
         * Commit and close the transaction
         */
        commit(): void;

        /**
         * Abort and close the transaction
         */
        abort(): void;

        /**
         * Abort a read-only transaction, but makes it renewable by calling
         * renew().
         */
        reset(): void;

        /**
         * Renew a read-only transaction after it has been reset.
         */
        renew(): void;
    };

    interface DelOptions {
        noDupData: boolean;
    }
    class Cursor<T extends Key = string> {
        constructor(txn: Txn, dbi: Dbi, keyType?: KeyType);

        goToFirst(options?: KeyType): T | null;
        goToLast(options?: KeyType): T | null;
        goToNext(options?: KeyType): T | null;
        goToPrev(options?: KeyType): T | null;
        goToKey(key: T, options?: KeyType): T | null;
        goToRange(key: T, options?: KeyType): T | null;

        goToFirstDup(options?: KeyType): T | null;
        goToLastDup(options?: KeyType): T | null;
        goToNextDup(options?: KeyType): T | null;
        goToPrevDup(options?: KeyType): T | null;
        goToDup(key: T, data: Value, options?: KeyType): T | null;
        goToDupRange(key: T, data: Value, options?: KeyType): T | null;

        getCurrentNumber(fn?: CursorCallback<number>): number | null;
        getCurrentBoolean(fn?: CursorCallback<boolean>): boolean | null;
        getCurrentString(fn?: CursorCallback<string>): string | null;
        getCurrentBinary(fn?: CursorCallback<Buffer>): Buffer | null;

        getCurrentStringUnsafe(fn?: CursorCallback<string>): string | null;
        getCurrentBinaryUnsafe(fn?: CursorCallback<Buffer>): Buffer | null;

        del(options?: DelOptions): void;

        close(): void;
    }
}