import LRUCache from "next/dist/compiled/lru-cache";
import { CACHE_ONE_YEAR, NEXT_CACHE_SOFT_TAGS_HEADER } from "../../../lib/constants";
let rateLimitedUntil = 0;
let memoryCache;
const CACHE_TAGS_HEADER = "x-vercel-cache-tags";
const CACHE_HEADERS_HEADER = "x-vercel-sc-headers";
const CACHE_STATE_HEADER = "x-vercel-cache-state";
const CACHE_REVALIDATE_HEADER = "x-vercel-revalidate";
const CACHE_FETCH_URL_HEADER = "x-vercel-cache-item-name";
const CACHE_CONTROL_VALUE_HEADER = "x-vercel-cache-control";
export default class FetchCache {
    static isAvailable(ctx) {
        return !!(ctx._requestHeaders["x-vercel-sc-host"] || process.env.SUSPENSE_CACHE_URL);
    }
    constructor(ctx){
        this.debug = !!process.env.NEXT_PRIVATE_DEBUG_CACHE;
        this.headers = {};
        this.headers["Content-Type"] = "application/json";
        if (CACHE_HEADERS_HEADER in ctx._requestHeaders) {
            const newHeaders = JSON.parse(ctx._requestHeaders[CACHE_HEADERS_HEADER]);
            for(const k in newHeaders){
                this.headers[k] = newHeaders[k];
            }
            delete ctx._requestHeaders[CACHE_HEADERS_HEADER];
        }
        const scHost = ctx._requestHeaders["x-vercel-sc-host"] || process.env.SUSPENSE_CACHE_URL;
        const scBasePath = ctx._requestHeaders["x-vercel-sc-basepath"] || process.env.SUSPENSE_CACHE_BASEPATH;
        if (process.env.SUSPENSE_CACHE_AUTH_TOKEN) {
            this.headers["Authorization"] = `Bearer ${process.env.SUSPENSE_CACHE_AUTH_TOKEN}`;
        }
        if (scHost) {
            this.cacheEndpoint = `https://${scHost}${scBasePath || ""}`;
            if (this.debug) {
                console.log("using cache endpoint", this.cacheEndpoint);
            }
        } else if (this.debug) {
            console.log("no cache endpoint available");
        }
        if (ctx.maxMemoryCacheSize) {
            if (!memoryCache) {
                if (this.debug) {
                    console.log("using memory store for fetch cache");
                }
                memoryCache = new LRUCache({
                    max: ctx.maxMemoryCacheSize,
                    length ({ value  }) {
                        var _JSON_stringify;
                        if (!value) {
                            return 25;
                        } else if (value.kind === "REDIRECT") {
                            return JSON.stringify(value.props).length;
                        } else if (value.kind === "IMAGE") {
                            throw new Error("invariant image should not be incremental-cache");
                        } else if (value.kind === "FETCH") {
                            return JSON.stringify(value.data || "").length;
                        } else if (value.kind === "ROUTE") {
                            return value.body.length;
                        }
                        // rough estimate of size of cache value
                        return value.html.length + (((_JSON_stringify = JSON.stringify(value.pageData)) == null ? void 0 : _JSON_stringify.length) || 0);
                    }
                });
            }
        } else {
            if (this.debug) {
                console.log("not using memory store for fetch cache");
            }
        }
    }
    async revalidateTag(tag) {
        if (this.debug) {
            console.log("revalidateTag", tag);
        }
        if (Date.now() < rateLimitedUntil) {
            if (this.debug) {
                console.log("rate limited ", rateLimitedUntil);
            }
            return;
        }
        try {
            const res = await fetch(`${this.cacheEndpoint}/v1/suspense-cache/revalidate?tags=${tag}`, {
                method: "POST",
                headers: this.headers,
                // @ts-expect-error not on public type
                next: {
                    internal: true
                }
            });
            if (res.status === 429) {
                const retryAfter = res.headers.get("retry-after") || "60000";
                rateLimitedUntil = Date.now() + parseInt(retryAfter);
            }
            if (!res.ok) {
                throw new Error(`Request failed with status ${res.status}.`);
            }
        } catch (err) {
            console.warn(`Failed to revalidate tag ${tag}`, err);
        }
    }
    async get(key, ctx) {
        const { tags , softTags , fetchCache , fetchIdx , fetchUrl  } = ctx;
        if (!fetchCache) return null;
        if (Date.now() < rateLimitedUntil) {
            if (this.debug) {
                console.log("rate limited");
            }
            return null;
        }
        let data = memoryCache == null ? void 0 : memoryCache.get(key);
        // memory cache data is only leveraged for up to 1 seconds
        // so that revalidation events can be pulled from source
        if (Date.now() - ((data == null ? void 0 : data.lastModified) || 0) > 2000) {
            data = undefined;
        }
        // get data from fetch cache
        if (!data && this.cacheEndpoint) {
            try {
                const start = Date.now();
                const fetchParams = {
                    internal: true,
                    fetchType: "cache-get",
                    fetchUrl: fetchUrl,
                    fetchIdx
                };
                const res = await fetch(`${this.cacheEndpoint}/v1/suspense-cache/${key}`, {
                    method: "GET",
                    headers: {
                        ...this.headers,
                        [CACHE_FETCH_URL_HEADER]: fetchUrl,
                        [CACHE_TAGS_HEADER]: (tags == null ? void 0 : tags.join(",")) || "",
                        [NEXT_CACHE_SOFT_TAGS_HEADER]: (softTags == null ? void 0 : softTags.join(",")) || ""
                    },
                    next: fetchParams
                });
                if (res.status === 429) {
                    const retryAfter = res.headers.get("retry-after") || "60000";
                    rateLimitedUntil = Date.now() + parseInt(retryAfter);
                }
                if (res.status === 404) {
                    if (this.debug) {
                        console.log(`no fetch cache entry for ${key}, duration: ${Date.now() - start}ms`);
                    }
                    return null;
                }
                if (!res.ok) {
                    console.error(await res.text());
                    throw new Error(`invalid response from cache ${res.status}`);
                }
                const cached = await res.json();
                if (!cached || cached.kind !== "FETCH") {
                    this.debug && console.log({
                        cached
                    });
                    throw new Error(`invalid cache value`);
                }
                const cacheState = res.headers.get(CACHE_STATE_HEADER);
                const age = res.headers.get("age");
                data = {
                    value: cached,
                    // if it's already stale set it to a time in the past
                    // if not derive last modified from age
                    lastModified: cacheState !== "fresh" ? Date.now() - CACHE_ONE_YEAR : Date.now() - parseInt(age || "0", 10) * 1000
                };
                if (this.debug) {
                    console.log(`got fetch cache entry for ${key}, duration: ${Date.now() - start}ms, size: ${Object.keys(cached).length}, cache-state: ${cacheState} tags: ${tags == null ? void 0 : tags.join(",")} softTags: ${softTags == null ? void 0 : softTags.join(",")}`);
                }
                if (data) {
                    memoryCache == null ? void 0 : memoryCache.set(key, data);
                }
            } catch (err) {
                // unable to get data from fetch-cache
                if (this.debug) {
                    console.error(`Failed to get from fetch-cache`, err);
                }
            }
        }
        return data || null;
    }
    async set(key, data, { fetchCache , fetchIdx , fetchUrl , tags  }) {
        if (!fetchCache) return;
        if (Date.now() < rateLimitedUntil) {
            if (this.debug) {
                console.log("rate limited");
            }
            return;
        }
        memoryCache == null ? void 0 : memoryCache.set(key, {
            value: data,
            lastModified: Date.now()
        });
        if (this.cacheEndpoint) {
            try {
                const start = Date.now();
                if (data !== null && "revalidate" in data) {
                    this.headers[CACHE_REVALIDATE_HEADER] = data.revalidate.toString();
                }
                if (!this.headers[CACHE_REVALIDATE_HEADER] && data !== null && "data" in data) {
                    this.headers[CACHE_CONTROL_VALUE_HEADER] = data.data.headers["cache-control"];
                }
                const body = JSON.stringify({
                    ...data,
                    // we send the tags in the header instead
                    // of in the body here
                    tags: undefined
                });
                if (this.debug) {
                    console.log("set cache", key);
                }
                const fetchParams = {
                    internal: true,
                    fetchType: "cache-set",
                    fetchUrl,
                    fetchIdx
                };
                const res = await fetch(`${this.cacheEndpoint}/v1/suspense-cache/${key}`, {
                    method: "POST",
                    headers: {
                        ...this.headers,
                        [CACHE_FETCH_URL_HEADER]: fetchUrl || "",
                        [CACHE_TAGS_HEADER]: (tags == null ? void 0 : tags.join(",")) || ""
                    },
                    body: body,
                    next: fetchParams
                });
                if (res.status === 429) {
                    const retryAfter = res.headers.get("retry-after") || "60000";
                    rateLimitedUntil = Date.now() + parseInt(retryAfter);
                }
                if (!res.ok) {
                    this.debug && console.log(await res.text());
                    throw new Error(`invalid response ${res.status}`);
                }
                if (this.debug) {
                    console.log(`successfully set to fetch-cache for ${key}, duration: ${Date.now() - start}ms, size: ${body.length}`);
                }
            } catch (err) {
                // unable to set to fetch-cache
                if (this.debug) {
                    console.error(`Failed to update fetch cache`, err);
                }
            }
        }
        return;
    }
}

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