import config from '@automattic/calypso-config';
import debugFactory from 'debug';
import { kebabCase } from 'lodash';
import { bumpStat } from 'calypso/lib/analytics/mc';
import { once } from 'calypso/lib/memoize-last';
import {
	getStoredItem as bypassGet,
	getAllStoredItems as bypassGetAll,
	setStoredItem as bypassSet,
	clearStorage as bypassClear,
	activate as activateBypass,
} from './bypass';
import { StoredItems } from './types';

const debug = debugFactory( 'calypso:browser-storage' );

let shouldBypass = false;
let shouldDisableIDB = false;

const DB_NAME = 'calypso';
const DB_VERSION = 2; // Match versioning of the previous localforage-based implementation.
const STORE_NAME = 'calypso_store';

const SANITY_TEST_KEY = 'browser-storage-sanity-test';

// eslint-disable-next-line @typescript-eslint/no-explicit-any
const isAffectedSafari =
	config.isEnabled( 'safari-idb-mitigation' ) &&
	typeof window !== 'undefined' &&
	!! window.IDBKeyRange?.lowerBound( 0 ).includes &&
	!! ( window as any ).webkitAudioContext &&
	!! window.PointerEvent;

debug( 'Safari IDB mitigation active: %s', isAffectedSafari );

export const supportsIDB = once( async () => {
	if ( typeof window === 'undefined' || ! window.indexedDB ) {
		debug( 'IDB not found in host' );
		return false;
	}

	if ( shouldDisableIDB ) {
		debug( 'IDB disabled' );
		return false;
	}

	try {
		const testValue = Date.now().toString();
		await idbSet( SANITY_TEST_KEY, testValue );
		await idbGet( SANITY_TEST_KEY );
		return true;
	} catch ( error ) {
		// IDB sanity test failed. Fall back to alternative method.
		return false;
	}
} );

const getDB = once( () => {
	const request = window.indexedDB.open( DB_NAME, DB_VERSION );
	return new Promise< IDBDatabase >( ( resolve, reject ) => {
		try {
			if ( request ) {
				request.onerror = ( event ) => {
					// InvalidStateError is special in Firefox.
					// We need to `preventDefault` to stop it from reaching the console.
					if ( request.error && request.error.name === 'InvalidStateError' ) {
						event.preventDefault();
					}
					reject( request.error );
				};
				request.onsuccess = () => {
					const db = request.result;

					// Add a general error handler for any future requests made against this db handle.
					// See https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API/Using_IndexedDB#Handling_Errors for
					// more information on how error events bubble with IndexedDB
					db.onerror = function ( errorEvent: any ) {
						debug( 'IDB Error', errorEvent );
						if ( errorEvent.target?.error?.name ) {
							bumpStat( 'calypso-browser-storage', kebabCase( errorEvent.target.error.name ) );

							if ( errorEvent.target.error.name === 'QuotaExceededError' ) {
								// we've blown through the quota. Turn off IDB for this page load
								shouldDisableIDB = true;
								supportsIDB.clear();
								debug( 'disabling IDB because we saw a QuotaExceededError' );
							}
						}
					};
					db.onversionchange = () => {
						// This fires when the database gets upgraded or when it gets deleted.
						// We need to close our handle to allow the change to proceed
						db.close();
					};
					resolve( db );
				};
				request.onupgradeneeded = () => request.result.createObjectStore( STORE_NAME );
			}
		} catch ( error ) {
			reject( error );
		}
	} );
} );

function idbGet< T >( key: string ): Promise< T | undefined > {
	return new Promise( ( resolve, reject ) => {
		getDB()
			.then( ( db ) => {
				const transaction = db.transaction( STORE_NAME, 'readonly' );
				const get = transaction.objectStore( STORE_NAME ).get( key );

				const success = () => resolve( get.result );
				const error = () => reject( transaction.error );

				transaction.oncomplete = success;
				transaction.onabort = error;
				transaction.onerror = error;
			} )
			.catch( ( err ) => reject( err ) );
	} );
}

type EventTargetWithCursorResult = EventTarget & { result: IDBCursorWithValue | null };

function idbGetAll( pattern?: RegExp ): Promise< StoredItems > {
	return getDB().then(
		( db ) =>
			new Promise( ( resolve, reject ) => {
				const results: StoredItems = {};
				const transaction = db.transaction( STORE_NAME, 'readonly' );
				const getAll = transaction.objectStore( STORE_NAME ).openCursor();

				const success = ( event: Event ) => {
					const cursor = ( event.target as EventTargetWithCursorResult ).result;
					if ( cursor ) {
						const { primaryKey: key, value } = cursor;
						if (
							key &&
							typeof key === 'string' &&
							key !== SANITY_TEST_KEY &&
							( ! pattern || pattern.test( key ) )
						) {
							results[ key ] = value;
						}
						cursor.continue();
					} else {
						// No more results.
						resolve( results );
					}
				};
				const error = () => reject( transaction.error );

				getAll.onsuccess = success;
				transaction.onabort = error;
				transaction.onerror = error;
			} )
	);
}

let idbWriteCount = 0;
let idbWriteBlock: Promise< void > | null = null;
async function idbSet< T >( key: string, value: T ): Promise< void > {
	// if there's a write lock, wait on it
	if ( idbWriteBlock ) {
		await idbWriteBlock;
	}
	// if we're on safari 13, we need to clear out the object store every
	// so many writes to make sure we don't chew up the transaction log
	if ( isAffectedSafari && ++idbWriteCount % 20 === 0 ) {
		await idbSafariReset();
	}

	return new Promise( ( resolve, reject ) => {
		getDB()
			.then( async ( db ) => {
				const transaction = db.transaction( STORE_NAME, 'readwrite' );
				transaction.objectStore( STORE_NAME ).put( value, key );

				const success = () => resolve();
				const error = () => reject( transaction.error );

				transaction.oncomplete = success;
				transaction.onabort = error;
				transaction.onerror = error;
			} )
			.catch( ( err ) => reject( err ) );
	} );
}

function idbClear(): Promise< void > {
	return new Promise( ( resolve, reject ) => {
		getDB()
			.then( ( db ) => {
				const transaction = db.transaction( STORE_NAME, 'readwrite' );
				transaction.objectStore( STORE_NAME ).clear();

				const success = () => resolve();
				const error = () => reject( transaction.error );

				transaction.oncomplete = success;
				transaction.onabort = error;
				transaction.onerror = error;
			} )
			.catch( ( err ) => reject( err ) );
	} );
}

function idbRemove(): Promise< void > {
	return new Promise( ( resolve, reject ) => {
		const deleteRequest = window.indexedDB.deleteDatabase( DB_NAME );
		deleteRequest.onsuccess = () => {
			getDB.clear();
			resolve();
		};
		deleteRequest.onerror = ( event ) => reject( event );
	} );
}

async function idbSafariReset() {
	if ( idbWriteBlock ) {
		return idbWriteBlock;
	}
	debug( 'performing safari idb mitigation' );
	idbWriteBlock = _idbSafariReset();
	idbWriteBlock.finally( () => {
		idbWriteBlock = null;
		debug( 'idb mitigation complete' );
	} );
	return idbWriteBlock;
}

async function _idbSafariReset(): Promise< void > {
	const items = await idbGetAll();

	await idbRemove();

	return new Promise( ( resolve, reject ) => {
		getDB().then(
			( db ) => {
				const transaction = db.transaction( STORE_NAME, 'readwrite' );
				const oStore = transaction.objectStore( STORE_NAME );
				// eslint-disable-next-line prefer-const
				for ( let [ key, value ] of Object.entries( items ) ) {
					oStore.put( value, key );
				}
				const success = () => resolve();
				const error = () => reject( transaction.error );

				transaction.oncomplete = success;
				transaction.onabort = error;
				transaction.onerror = error;
			},
			( err ) => reject( err )
		);
	} );
}

/**
 * Whether persistent storage should be bypassed, using a memory store instead.
 * @param shouldBypassPersistentStorage Whether persistent storage should be bypassed.
 */
export function bypassPersistentStorage( shouldBypassPersistentStorage: boolean ) {
	shouldBypass = shouldBypassPersistentStorage;

	if ( shouldBypass ) {
		activateBypass();
	}
}

/**
 * Get a stored item.
 * @param key The stored item key.
 * @returns A promise with the stored value. `undefined` if missing.
 */
export async function getStoredItem< T >( key: string ): Promise< T | undefined > {
	if ( shouldBypass ) {
		return await bypassGet( key );
	}

	const idbSupported = await supportsIDB();
	if ( ! idbSupported ) {
		try {
			const valueString = window.localStorage.getItem( key );
			if ( valueString === undefined || valueString === null ) {
				return undefined;
			}

			return JSON.parse( valueString );
		} catch {
			return undefined;
		}
	}

	return await idbGet( key );
}

/**
 * Get all stored items.
 * @param pattern The pattern to match on returned item keys.
 * @returns A promise with the stored key/value pairs as an object. Empty if none.
 */
export async function getAllStoredItems( pattern?: RegExp ): Promise< StoredItems > {
	if ( shouldBypass ) {
		return await bypassGetAll( pattern );
	}

	const idbSupported = await supportsIDB();
	if ( ! idbSupported ) {
		try {
			const entries = Object.entries( window.localStorage ).map( ( [ key, value ] ) => [
				key,
				value !== undefined ? JSON.parse( value ) : undefined,
			] );

			if ( ! pattern ) {
				return Object.fromEntries( entries );
			}

			return Object.fromEntries( entries.filter( ( [ key ] ) => pattern.test( key ) ) );
		} catch {
			return {};
		}
	}

	return await idbGetAll( pattern );
}

/**
 * Set an item in storage.
 * @param key The key to store the item under.
 * @param value The value of the item to be stored.
 * @returns A promise that gets resolved when the item is successfully stored.
 */
export async function setStoredItem< T >( key: string, value: T ): Promise< void > {
	if ( shouldBypass ) {
		return await bypassSet( key, value );
	}

	const idbSupported = await supportsIDB();
	if ( ! idbSupported ) {
		try {
			window.localStorage.setItem( key, JSON.stringify( value ) );
		} catch {
			// Do nothing.
		}
		return;
	}

	return await idbSet( key, value );
}

/**
 * Clear all stored items.
 * @returns A promise that gets resolved when all items are successfully cleared.
 */
export async function clearStorage(): Promise< void > {
	if ( shouldBypass ) {
		return await bypassClear();
	}

	const idbSupported = await supportsIDB();
	if ( ! idbSupported ) {
		try {
			window.localStorage.clear();
		} catch {
			// Do nothing.
		}
		return;
	}

	return await idbClear();
}