import type {JSONValue, ToJSON} from './json.js';

import type {

Invoke,

OpenTransactionRequest,

CommitTransactionResponse,

} from './repm-invoker.js';

import type {ScanOptions} from './scan-options.js';

import {ScanResult} from './scan-iterator.js';

import {TransactionClosedError} from './transaction-closed-error.js';

/**

* ReadTransactions are used with `Replicache.query` and allows read operations

* on the database.

*/

export interface ReadTransaction {

/**

* Get a single value from the database. If the key is not present this

* returns `undefined`.

*/

get(key: string): Promise<JSONValue | undefined>;

/**

* Determines if a single key is present in the database.

*/

has(key: string): Promise<boolean>;

/**

* Gets many values from the database. This returns a `ScanResult` which

* implements `AsyncIterable`. It also has methods to iterate over the `keys`

* and `entries`.

*

* It the `ScanResult` is used after the `ReadTransaction` has been closed it

* will throw a {@link TransactionClosedError}.

*/

scan(options?: ScanOptions): ScanResult;

/**

* Convenience for scan() that reads all results into an array.

*/

scanAll(options?: ScanOptions): Promise<[string, JSONValue][]>;

}

export function throwIfClosed(tx: {closed: boolean}): void {

if (tx.closed) {

throw new TransactionClosedError();

}

}

export class ReadTransactionImpl implements ReadTransaction {

private _transactionId = -1;

protected readonly _invoke: Invoke;

protected _closed = false;

constructor(invoke: Invoke) {

this._invoke = invoke;

}

async get(key: string): Promise<JSONValue | undefined> {

throwIfClosed(this);

const result = await this._invoke('get', {

transactionId: this._transactionId,

key,

});

if (!result.has) {

return undefined;

}

return JSON.parse(result.value);

}

async has(key: string): Promise<boolean> {

throwIfClosed(this);

const result = await this._invoke('has', {

transactionId: this._transactionId,

key,

});

return result['has'];

}

scan({prefix = '', start}: ScanOptions = {}): ScanResult {

return new ScanResult(prefix, start, this._invoke, () => this, false);

}

async scanAll(options: ScanOptions = {}): Promise<[string, JSONValue][]> {

const it = this.scan(options).entries();

const result = [];

for await (const pair of it) {

result.push(pair);

}

return result;

}

get id(): number {

return this._transactionId;

}

get closed(): boolean {

return this._closed;

}

async open(args: OpenTransactionRequest): Promise<void> {

const {transactionId} = await this._invoke('openTransaction', args);

this._transactionId = transactionId;

}

async close(): Promise<void> {

try {

this._closed = true;

await this._invoke('closeTransaction', {

transactionId: this._transactionId,

});

} catch (ex) {

console.error('Failed to close transaction', ex);

}

}

}

/**

* WriteTransactions are used with `Replicache.register` and allows read and

* write operations on the database.

*/

export interface WriteTransaction extends ReadTransaction {

/**

* Sets a single value in the database. The `value` will be encoded using

* `JSON.stringify`.

*/

put(key: string, value: JSONValue | ToJSON): Promise<void>;

/**

* Removes a key and its value from the database. Returns true if there was a

* key to remove.

*/

del(key: string): Promise<boolean>;

}

export class WriteTransactionImpl extends ReadTransactionImpl

implements WriteTransaction {

async put(key: string, value: JSONValue | ToJSON): Promise<void> {

throwIfClosed(this);

await this._invoke('put', {

transactionId: this.id,

key,

value: JSON.stringify(value),

});

}

async del(key: string): Promise<boolean> {

throwIfClosed(this);

const result = await this._invoke('del', {

transactionId: this.id,

key,

});

return result.ok;

}

async commit(): Promise<CommitTransactionResponse> {

this._closed = true;

const commitRes = await this._invoke('commitTransaction', {

transactionId: this.id,

});

return commitRes;

}

}