const { stores, STORE_KEYS } = require("./stores");

function decompress(compressedItems) {
    const items = [];
    const storeLookup = compressedItems.stores;
    const data = compressedItems.data;
    const numItems = compressedItems.n;
    let i = 0;
    while (items.length < numItems) {
        const store = storeLookup[data[i++]];
        const id = data[i++];
        const name = data[i++];
        const numPrices = data[i++];
        const prices = [];
        for (let j = 0; j < numPrices; j++) {
            const date = data[i++];
            const price = data[i++];
            prices.push({
                date: date.substring(0, 4) + "-" + date.substring(4, 6) + "-" + date.substring(6, 8),
                price,
            });
        }
        const unit = data[i++];
        const quantity = data[i++];
        const isWeighted = data[i++] == 1;
        const bio = data[i++] == 1;
        const url = stores[store].getUrl({ id, name, url: data[i++] });

        items.push({
            store,
            id,
            name,
            price: prices[0].price,
            priceHistory: prices,
            isWeighted,
            unit,
            quantity,
            bio,
            url,
        });
    }
    return items;
}

exports.items = [];
exports.lookup = {};

exports.load = async () => {
    now = performance.now();
    const compressedItemsPerStore = [];
    for (const store of STORE_KEYS) {
        compressedItemsPerStore.push(
            new Promise(async (resolve) => {
                const now = performance.now();
                try {
                    const response = await fetch(`data/latest-canonical.${store}.compressed.json`);
                    const json = await response.json();
                    console.log(`Loading compressed items for ${store} took ${(performance.now() - now) / 1000} secs`);
                    resolve(decompress(json));
                } catch (e) {
                    console.error(e);
                    console.log(
                        `Error while loading compressed items for ${store}. It took ${(performance.now() - now) / 1000} secs, continueing...`
                    );
                    resolve([]);
                }
            })
        );
    }
    const items = [].concat(...(await Promise.all(compressedItemsPerStore)));
    console.log("Loading compressed items in parallel took " + (performance.now() - now) / 1000 + " secs");

    const lookup = {};
    now = performance.now();
    for (const item of items) {
        lookup[item.store + item.id] = item;
        item.search = item.name + " " + item.quantity + " " + item.unit;
        item.search = item.search.toLowerCase().replace(",", ".");

        item.numPrices = item.priceHistory.length;
        item.priceOldest = item.priceHistory[item.priceHistory.length - 1].price;
        item.dateOldest = item.priceHistory[item.priceHistory.length - 1].date;
        item.date = item.priceHistory[0].date;
        let highestPriceBefore = -1;
        let lowestPriceBefore = 100000;
        for (let i = 1; i < item.priceHistory.length; i++) {
            const price = item.priceHistory[i];
            if (i < 10) {
                item["price" + i] = price.price;
                item["date" + i] = price.date;
            }
            highestPriceBefore = Math.max(highestPriceBefore, price.price);
            lowestPriceBefore = Math.min(lowestPriceBefore, price.price);
        }
        if (highestPriceBefore == -1) highestPriceBefore = item.price;
        if (lowestPriceBefore == 100000) lowestPriceBefore = item.price;
        item.highestBefore = highestPriceBefore;
        item.lowestBefore = lowestPriceBefore;
    }
    console.log("Processing items took " + (performance.now() - now) / 1000 + " secs");

    exports.items = items;
    exports.lookup = lookup;
};