'use strict';

const instanceOfAny = (object, constructors) => constructors.some(c => object instanceof c);

let idbProxyableTypes;
let cursorAdvanceMethods;
// This is a function to prevent it throwing up in node environments.
function getIdbProxyableTypes() {
    return (idbProxyableTypes ||
        (idbProxyableTypes = [
            IDBDatabase,
            IDBObjectStore,
            IDBIndex,
            IDBCursor,
            IDBTransaction,
        ]));
}
// This is a function to prevent it throwing up in node environments.
function getCursorAdvanceMethods() {
    return (cursorAdvanceMethods ||
        (cursorAdvanceMethods = [
            IDBCursor.prototype.advance,
            IDBCursor.prototype.continue,
            IDBCursor.prototype.continuePrimaryKey,
        ]));
}
const cursorRequestMap = new WeakMap();
const transactionDoneMap = new WeakMap();
const transactionStoreNamesMap = new WeakMap();
const transformCache = new WeakMap();
const reverseTransformCache = new WeakMap();
function promisifyRequest(request) {
    const promise = new Promise((resolve, reject) => {
        const unlisten = () => {
            request.removeEventListener('success', success);
            request.removeEventListener('error', error);
        };
        const success = () => {
            resolve(wrap(request.result));
            unlisten();
        };
        const error = () => {
            reject(request.error);
            unlisten();
        };
        request.addEventListener('success', success);
        request.addEventListener('error', error);
    });
    promise
        .then(value => {
        // Since cursoring reuses the IDBRequest (*sigh*), we cache it for later retrieval
        // (see wrapFunction).
        if (value instanceof IDBCursor) {
            cursorRequestMap.set(value, request);
        }
        // Catching to avoid "Uncaught Promise exceptions"
    })
        .catch(() => { });
    // This mapping exists in reverseTransformCache but doesn't doesn't exist in transformCache. This
    // is because we create many promises from a single IDBRequest.
    reverseTransformCache.set(promise, request);
    return promise;
}
function cacheDonePromiseForTransaction(tx) {
    // Early bail if we've already created a done promise for this transaction.
    if (transactionDoneMap.has(tx))
        return;
    const done = new Promise((resolve, reject) => {
        const unlisten = () => {
            tx.removeEventListener('complete', complete);
            tx.removeEventListener('error', error);
            tx.removeEventListener('abort', error);
        };
        const complete = () => {
            resolve();
            unlisten();
        };
        const error = () => {
            reject(tx.error);
            unlisten();
        };
        tx.addEventListener('complete', complete);
        tx.addEventListener('error', error);
        tx.addEventListener('abort', error);
    });
    // Cache it for later retrieval.
    transactionDoneMap.set(tx, done);
}
let idbProxyTraps = {
    get(target, prop, receiver) {
        if (target instanceof IDBTransaction) {
            // Special handling for transaction.done.
            if (prop === 'done')
                return transactionDoneMap.get(target);
            // Polyfill for objectStoreNames because of Edge.
            if (prop === 'objectStoreNames') {
                return target.objectStoreNames || transactionStoreNamesMap.get(target);
            }
            // Make tx.store return the only store in the transaction, or undefined if there are many.
            if (prop === 'store') {
                return receiver.objectStoreNames[1]
                    ? undefined
                    : receiver.objectStore(receiver.objectStoreNames[0]);
            }
        }
        // Else transform whatever we get back.
        return wrap(target[prop]);
    },
    has(target, prop) {
        if (target instanceof IDBTransaction &&
            (prop === 'done' || prop === 'store')) {
            return true;
        }
        return prop in target;
    },
};
function addTraps(callback) {
    idbProxyTraps = callback(idbProxyTraps);
}
function wrapFunction(func) {
    // Due to expected object equality (which is enforced by the caching in `wrap`), we
    // only create one new func per func.
    // Edge doesn't support objectStoreNames (booo), so we polyfill it here.
    if (func === IDBDatabase.prototype.transaction &&
        !('objectStoreNames' in IDBTransaction.prototype)) {
        return function (storeNames, ...args) {
            const tx = func.call(unwrap(this), storeNames, ...args);
            transactionStoreNamesMap.set(tx, storeNames.sort ? storeNames.sort() : [storeNames]);
            return wrap(tx);
        };
    }
    // Cursor methods are special, as the behaviour is a little more different to standard IDB. In
    // IDB, you advance the cursor and wait for a new 'success' on the IDBRequest that gave you the
    // cursor. It's kinda like a promise that can resolve with many values. That doesn't make sense
    // with real promises, so each advance methods returns a new promise for the cursor object, or
    // undefined if the end of the cursor has been reached.
    if (getCursorAdvanceMethods().includes(func)) {
        return function (...args) {
            // Calling the original function with the proxy as 'this' causes ILLEGAL INVOCATION, so we use
            // the original object.
            func.apply(unwrap(this), args);
            return wrap(cursorRequestMap.get(this));
        };
    }
    return function (...args) {
        // Calling the original function with the proxy as 'this' causes ILLEGAL INVOCATION, so we use
        // the original object.
        return wrap(func.apply(unwrap(this), args));
    };
}
function transformCachableValue(value) {
    if (typeof value === 'function')
        return wrapFunction(value);
    // This doesn't return, it just creates a 'done' promise for the transaction,
    // which is later returned for transaction.done (see idbObjectHandler).
    if (value instanceof IDBTransaction)
        cacheDonePromiseForTransaction(value);
    if (instanceOfAny(value, getIdbProxyableTypes()))
        return new Proxy(value, idbProxyTraps);
    // Return the same value back if we're not going to transform it.
    return value;
}
function wrap(value) {
    // We sometimes generate multiple promises from a single IDBRequest (eg when cursoring), because
    // IDB is weird and a single IDBRequest can yield many responses, so these can't be cached.
    if (value instanceof IDBRequest)
        return promisifyRequest(value);
    // If we've already transformed this value before, reuse the transformed value.
    // This is faster, but it also provides object equality.
    if (transformCache.has(value))
        return transformCache.get(value);
    const newValue = transformCachableValue(value);
    // Not all types are transformed.
    // These may be primitive types, so they can't be WeakMap keys.
    if (newValue !== value) {
        transformCache.set(value, newValue);
        reverseTransformCache.set(newValue, value);
    }
    return newValue;
}
const unwrap = (value) => reverseTransformCache.get(value);

exports.wrap = wrap;
exports.addTraps = addTraps;
exports.instanceOfAny = instanceOfAny;
exports.reverseTransformCache = reverseTransformCache;
exports.unwrap = unwrap;
