const cardDatabase = {
	cards: null as Card[] | null,
	lastOfficialCardNumber: 0,
	_byAltNumber: [ ] as Card[],

	// Upcoming cards are identified with a negative number, as their actual numbers aren't known until their release.
	// The placeholder numbers will be kept as alternate numbers then, to avoid breaking replay and saved deck data that uses them.
	get(number: number) {
		if (cardDatabase.cards == null) throw new Error('Card database not loaded');
		if (number > 0) {
			number--;
			if (number < cardDatabase.lastOfficialCardNumber) return cardDatabase.cards[number];
		} else if (number < 0) {
			const card = cardDatabase._byAltNumber[-number];
			if (card) return card;
		}
		throw new RangeError(`No card with number ${number}`);
	},
	isValidCardNumber(number: number) {
		return number > 0 ? number <= cardDatabase.lastOfficialCardNumber : cardDatabase._byAltNumber[-number] != undefined;
	},
	loadAsync() {
		return new Promise<Card[]>((resolve, reject) => {
			if (cardDatabase.cards != null) {
				resolve(cardDatabase.cards);
				return;
			}
			const cardListRequest = new XMLHttpRequest();
			cardListRequest.open('GET', `${config.apiBaseUrl}/cards`);
			cardListRequest.addEventListener('load', e => {
				const cards: Card[] = [ ];
				if (cardListRequest.status == 200) {
					const s = cardListRequest.responseText;
					const response = JSON.parse(s) as object[];
					for (const o of response) {
						const card = Card.fromJson(o);
						cards.push(card);
						cardDatabase.lastOfficialCardNumber = Math.max(cardDatabase.lastOfficialCardNumber, card.number);
						if (card.number < 0) cardDatabase._byAltNumber[-card.number] = card;
						else if (card.altNumber != null && card.altNumber < 0) cardDatabase._byAltNumber[-card.altNumber] = card;
					}
					cardDatabase.cards = cards;

					if (window.location.protocol == 'file:') {
						// If debugging locally, just read the files from the assets directory.
						for (const card of cardDatabase.cards!) {
							card.imageUrl = `assets/external/card/${card.artFileName}.webp`
						}
						resolve(cards);
						return;
					}
					// Otherwise, download and extract card images from a .tar package.
					const imagesRequest = new XMLHttpRequest();
					imagesRequest.responseType = 'arraybuffer';
					imagesRequest.open('GET', 'assets/external/card.tar');
					imagesRequest.addEventListener('load', () => {
						if (imagesRequest.status == 200 && imagesRequest.response) {
							const buffer = imagesRequest.response as ArrayBuffer;
							untar(buffer).then(files => {
								for (const tarFile of files) {
									const card = cardDatabase.cards!.find(c => tarFile.name == `${c.artFileName}.webp`);
									if (!card) continue;
									card.imageUrl = tarFile.getBlobUrl();
								}
								resolve(cards);
							});
						} else {
							reject(new Error(`Error downloading card images: response was ${imagesRequest.status}`));
						}
					});
					imagesRequest.addEventListener('error', () => {
						reject(new Error('Error downloading card images: no further information.'))
					});
					imagesRequest.send();
				} else {
					reject(new Error(`Error downloading card database: response was ${cardListRequest.status}`));
				}
			});
			cardListRequest.addEventListener('error', e => {
				reject(new Error('Error downloading card database: no further information.'))
			});
			cardListRequest.send();
		});
	}
}