import type { Printful, Webflow } from "./util/types";
import { formatSlug, type DeepPartial } from "./util/misc";
import { WebflowClient } from "./webflow";
import { PrintfulClient } from "./printful";
import { redis } from "bun";
import pino from "pino";

const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));

type ProductEntry = {
    colorGroup: string | null;
    product: Printful.Products.Product;
};

type MetaPrintfulProduct = {
    name: string;
    webflowProductId: string;
    entries: ProductEntry[];
};

type SyncState = {
    printfulProductIds: number[];
};

type SyncOptions = {
    filter?: {
        printfulProductIds?: number[] | number;
    }
};

export class ProductSyncer {
    private log: pino.Logger;

    constructor(
        private printful: PrintfulClient,
        private webflow: WebflowClient,
        log?: pino.Logger,
    ) {
        this.log = (log ?? pino({ level: "silent" })).child({ component: "ProductSyncer" });
    }

    async sync(opt: SyncOptions = {}): Promise<boolean> {
        if (typeof opt.filter?.printfulProductIds === "number")
            opt.filter.printfulProductIds = [opt.filter.printfulProductIds];

        this.log.info("attempting sync run");
        const canRun = await this.run();
        if (!canRun) return false;

        try {
            const syncStart = Date.now();
            if (opt.filter?.printfulProductIds)
                this.log.info({ printfulProductIds: opt.filter.printfulProductIds }, "sync started (filtered)");
            else
                this.log.info("sync started (all)");

            this.log.debug("retrieving webflow products");
            const allWebflowProducts = await this.webflow.Products.list({ forceAll: true });

            this.log.debug("retrieving printful products");
            const allPrintfulProducts = await this.printful.Products.list({ forceAll: true });

            this.log.info({ printfulProductCount: allPrintfulProducts.length, filter: opt.filter ?? "N/A" }, "generating meta printful products");
            const metaPrintfulProducts = await this.generateMetaPrintfulProducts(allWebflowProducts, allPrintfulProducts, opt);

            for (const metaPrintfulProduct of metaPrintfulProducts) {
                this.log.info({ name: metaPrintfulProduct.name, externalId: metaPrintfulProduct.webflowProductId }, "syncing meta printful product");

                await this.setState({
                    printfulProductIds: metaPrintfulProduct.entries.map((e) => e.product.sync_product.id),
                });

                const newWebflowSkus: DeepPartial<Webflow.Products.Skus.Sku>[] = this.generateWebflowSkus(metaPrintfulProduct);
                const foundColors = new Set<string>(
                    newWebflowSkus.map((sku) => sku.fieldData?.["sku-values"]?.["color"]).filter((v) => v !== undefined)
                );
                const foundSizes = new Set<string>(
                    newWebflowSkus.map((sku) => sku.fieldData?.["sku-values"]?.["size"]).filter((v) => v !== undefined)
                );

                if (!newWebflowSkus[0]) throw new Error("no webflow SKUs generated — all variants were filtered out");

                const webflowProductFieldData = {
                    name: metaPrintfulProduct.name,
                    slug: formatSlug(metaPrintfulProduct.name),
                    shippable: true,
                    "tax-category": "standard-taxable",
                    "sku-properties": [
                        {
                            id: "color",
                            name: "Color",
                            enum: Array.from(foundColors).map((color) => ({
                                id: color,
                                slug: formatSlug(color),
                                name: color,
                            })),
                        },
                        {
                            id: "size",
                            name: "Size",
                            enum: Array.from(foundSizes).map((size) => ({
                                id: size,
                                slug: formatSlug(size),
                                name: size,
                            })),
                        },
                    ],
                };

                const webflowProduct = allWebflowProducts.find((wp) => wp.product.id === metaPrintfulProduct.webflowProductId);

                if (webflowProduct) {
                    this.log.info({ id: webflowProduct.product.id }, "existing webflow product found, updating it");

                    // do not update images
                    for (const sku of newWebflowSkus) delete sku.fieldData?.["main-image"];

                    // handle case where webflow SKU created by associated printful variant external_id update failed
                    if (!newWebflowSkus[0].id) {
                        this.log.warn({ webflowSku: newWebflowSkus[0] }, "missing webflow SKU id");
                        const webflowSkuMatch = this.resolveWebflowSku(
                            webflowProduct.skus,
                            newWebflowSkus[0].fieldData?.["sku-values"]?.["color"],
                            newWebflowSkus[0].fieldData?.["sku-values"]?.["size"],
                        );

                        if (webflowSkuMatch)
                            newWebflowSkus[0].id = webflowSkuMatch.id;
                        else
                            this.log.warn({ webflowSku: newWebflowSkus[0] }, "could not find existing webflow SKU that matches");
                    }

                    await this.webflow.Products.update(webflowProduct.product.id, {
                        product: { fieldData: webflowProductFieldData },
                        sku: newWebflowSkus[0],
                    });

                    for (const newWebflowSku of newWebflowSkus) {
                        const existingWebflowSku = this.resolveWebflowSku(
                            webflowProduct.skus,
                            newWebflowSku.fieldData?.["sku-values"]?.["color"],
                            newWebflowSku.fieldData?.["sku-values"]?.["size"],
                            newWebflowSku.id,
                        );
                        if (existingWebflowSku) {
                            await this.webflow.Products.Skus.update(
                                metaPrintfulProduct.webflowProductId,
                                existingWebflowSku.id,
                                newWebflowSku,
                            );
                        } else {
                            await this.webflow.Products.Skus.create(
                                metaPrintfulProduct.webflowProductId,
                                [newWebflowSku],
                            );
                        }
                    }
                } else {
                    this.log.info("existing webflow product not found, creating it");

                    const webflowProductId = await this.webflow.Products.create({
                        product: { fieldData: webflowProductFieldData },
                        sku: newWebflowSkus[0],
                    });
                    metaPrintfulProduct.webflowProductId = webflowProductId;

                    if (newWebflowSkus.length > 1)
                        await this.webflow.Products.Skus.create(webflowProductId, newWebflowSkus.slice(1));
                }

                // Re-fetch after SKU mutations so newly created SKUs have their real IDs.
                const freshWebflowProduct = await this.webflow.Products.get(metaPrintfulProduct.webflowProductId);
                if (!freshWebflowProduct) throw new Error("webflow product missing");

                // Update printful external IDs
                for (const { colorGroup, product: printfulProduct } of metaPrintfulProduct.entries) {
                    const expectedExternalId = colorGroup ?
                        `${metaPrintfulProduct.webflowProductId}-${colorGroup}` :
                        metaPrintfulProduct.webflowProductId;
                    if (printfulProduct.sync_product.external_id === expectedExternalId) continue;

                    const printfulVariantPatches: DeepPartial<Printful.Products.SyncVariant>[] = [];
                    for (const printfulVariant of printfulProduct.sync_variants) {
                        const webflowSku = this.resolveWebflowSku(
                            freshWebflowProduct.skus,
                            colorGroup ?? printfulVariant.color,
                            printfulVariant.size,
                        );
                        if (webflowSku) {
                            printfulVariantPatches.push({
                                id: printfulVariant.id,
                                external_id: String(webflowSku.id),
                            });
                        }
                    }

                    await sleep(10000);
                    this.log.info({ printfulProduct: printfulProduct.sync_product.id, externalId: expectedExternalId }, "updating printful product's external ID");
                    await this.printful.Products.update(printfulProduct.sync_product.id, {
                        sync_product: {
                            id: printfulProduct.sync_product.id,
                            external_id: expectedExternalId,
                        },
                        sync_variants: printfulVariantPatches,
                    });
                }
            }

            this.log.info({ durationMs: Date.now() - syncStart }, "sync complete");
        } finally {
            try {
                await redis.del("commerce:sync:lock");
                await redis.del("commerce:sync:state");
            } catch {
                this.log.error("failed to reset sync state");
            }
        }
        return true;
    }

    parseColorGroup(name: string): string | null {
        const m = name.match(/\[([^\]]+)\]/);
        return m?.[1] ?? null;
    }

    private generateWebflowSkus(metaPrintfulProduct: MetaPrintfulProduct): DeepPartial<Webflow.Products.Skus.Sku>[] {
        const webflowSkus: DeepPartial<Webflow.Products.Skus.Sku>[] = [];
        for (const { colorGroup, product: printfulProduct } of metaPrintfulProduct.entries) {
            const isColorGrouped = colorGroup !== null;
            for (const printfulVariant of printfulProduct.sync_variants) {
                if (isColorGrouped) {
                    // Only include sizes present across every color variant.
                    const sizeInAll = metaPrintfulProduct.entries.every((e) =>
                        e.product.sync_variants.some((sv) => sv.size === printfulVariant.size)
                    );
                    if (!sizeInAll) continue;
                }

                const color = isColorGrouped ?
                    colorGroup :
                    printfulVariant.color;

                this.log.debug(
                    { color, size: printfulVariant.size, retailPrice: printfulVariant.retail_price },
                    "generating webflow SKU from printful variant"
                );

                webflowSkus.push({
                    id: printfulVariant.external_id,
                    fieldData: {
                        name: printfulVariant.name,
                        slug: formatSlug(printfulVariant.name),
                        "sku-values": {
                            color,
                            size: printfulVariant.size,
                        },
                        price: {
                            value: Math.floor(+printfulVariant.retail_price * 100),
                            unit: printfulVariant.currency,
                            currency: printfulVariant.currency,
                        },
                        "main-image": PrintfulClient.Util.getVariantMainImage(printfulVariant),
                    },
                });
            }
        }

        return webflowSkus;
    }

    async generateMetaPrintfulProducts(
        allWebflowProducts: Webflow.Products.ProductAndSkus[],
        allPrintfulProducts: Printful.Products.SyncProduct[],
        opt: SyncOptions,
    ) {
        if (typeof opt.filter?.printfulProductIds === "number")
            opt.filter.printfulProductIds = [opt.filter.printfulProductIds];

        const metaNameFilter = opt.filter?.printfulProductIds
            ?.map((id) => allPrintfulProducts.find((p) => p.id === id))
            ?.filter((p) => p !== undefined)
            ?.map((p) => this.getMetaPrintfulProductName(p));

        const metaPrintfulProducts: MetaPrintfulProduct[] = [];
        for (const printfulProduct of allPrintfulProducts) {
            const metaName = this.getMetaPrintfulProductName(printfulProduct);
            const colorGroup = this.parseColorGroup(printfulProduct.name);
            const webflowProductId = this.isPrintfulProductSynced(printfulProduct, allWebflowProducts) ?
                printfulProduct.external_id.split("-")[0] ?? "" :
                "";

            if (metaNameFilter && !metaNameFilter.includes(metaName)) continue;

            let metaPrintfulProduct = metaPrintfulProducts.find((mp) => mp.name === metaName);
            if (!metaPrintfulProduct) {
                this.log.debug({ metaName, colorGroup, webflowProductId }, "generating meta printful product");
                metaPrintfulProduct = {
                    name: metaName,
                    webflowProductId,
                    entries: [],
                };
                metaPrintfulProducts.push(metaPrintfulProduct);
            } else if (!metaPrintfulProduct.webflowProductId && webflowProductId) {
                // Prefer a non-empty webflowProductId so a newly added color doesn't shadow an already-synced color's ID.
                metaPrintfulProduct.webflowProductId = webflowProductId;
            }

            const fullPrintfulProduct = await this.printful.Products.get(printfulProduct.id);
            if (!fullPrintfulProduct) throw new Error(`Printful product ${printfulProduct.id} not found`);

            const isDuplicate = allPrintfulProducts.some((p) => p.id !== printfulProduct.id && p.name === printfulProduct.name);
            if (isDuplicate) this.log.warn({ printfulProductName: printfulProduct.name }, "found duplicate printful product");

            this.log.debug({ name: metaName, colorGroup }, "adding entry to meta printful product");
            metaPrintfulProduct.entries.push({ colorGroup, product: fullPrintfulProduct });
        }

        return metaPrintfulProducts;
    }

    getMetaPrintfulProductName(printfulProduct: Printful.Products.SyncProduct): string {
        const color = this.parseColorGroup(printfulProduct.name);
        if (color) return printfulProduct.name.replace(`[${color}]`, "").trimEnd();
        return printfulProduct.name;
    }

    private resolveWebflowSku(
        existingSkus: Webflow.Products.Skus.Sku[],
        color: string | undefined,
        size: string | undefined,
        id?: string,
    ): Webflow.Products.Skus.Sku | undefined {
        return existingSkus.find(
            (sku) =>
                (id && sku.id === id) ||
                (sku.fieldData["sku-values"]?.["color"] === color &&
                    sku.fieldData["sku-values"]?.["size"] === size),
        );
    }

    private isPrintfulProductSynced(printfulProduct: Printful.Products.SyncProduct, allWebflowProducts: Webflow.Products.ProductAndSkus[]) {
        return allWebflowProducts.some((wp) => wp.product.id === printfulProduct.external_id.split("-")[0]);
    }

    async isRunning(): Promise<boolean> {
        return !!await redis.get("commerce:sync:lock");
    }

    async getState(): Promise<SyncState> {
        const val = await redis.get("commerce:sync:state");
        if (val) return JSON.parse(val);
        return { printfulProductIds: [] };
    }

    private async setState(state: SyncState) {
        await redis.set("commerce:sync:state", JSON.stringify(state), "EX", 1800);
    }

    private async run(): Promise<boolean> {
        return !!await redis.set("commerce:sync:lock", "1", "NX", "EX", "1800");
    }
}