module csgs.task;

import slf4d;
import scheduled;
import scheduled.taskpool_scheduler;

import std.datetime;
import std.typecons;
import std.json;
import std.string;
import std.file;
import std.stdio;

import csgs.extract;

void startScheduledTasks() {
    JobScheduler scheduler = new TaskPoolScheduler();

    Job cleanJob = new FunctionJob(&cleanOldExtracts);
    scheduler.addJob(cleanJob, new FixedIntervalSchedule(days(1)));

    Job updateCheckJob = new FunctionJob(&checkForExtractorUpdate);
    scheduler.addJob(updateCheckJob, new FixedIntervalSchedule(hours(1)));

    scheduler.start();
}

private void cleanOldExtracts() {
    import std.file;
    immutable MAX_AGE = days(5);
    info("Cleaning old extracts.");
    if (!exists(EXTRACTS_DIR)) return;
    immutable SysTime now = Clock.currTime();
    foreach (DirEntry entry; dirEntries(EXTRACTS_DIR, SpanMode.shallow, false)) {
        if (entry.isDir) {
            infoF!"Removing directory %s."(entry.name);
            rmdirRecurse(entry.name);
        } else if (entry.isFile) {
            immutable Duration age = now - entry.timeLastModified();
            if (age > MAX_AGE) {
                infoF!"Removing extract %s because it's too old."(entry.name);
                std.file.remove(entry.name);
            }
        }
    }
}

private void checkForExtractorUpdate() {
    import requests;
    import std.json;
    import std.stdio;
    import std.string;
    import std.file;
    info("Checking for MaterialsExtractor program updates.");

    // First request the latest release from GitHub API:
    Request req = Request();
    req.addHeaders(["Accept": "application/vnd.github+json"]);
    Response resp = req.get("https://api.github.com/repos/andrewlalis/MaterialsExtractor/releases/latest");
    if (resp.code() != 200) {
        warnF!"Failed to get the latest MaterialsExtractor release. Status code %d."(resp.code);
        return;
    }
    JSONValue responseJson = parseJSON(resp.responseBody.toString());

    // Get the release's version, compare it with our current version.
    immutable string releaseVersion = responseJson.object["tag_name"].str;
    infoF!"Found release version %s"(releaseVersion);
    Nullable!string currentVersion = getCurrentExtractorVersion();
    if (!currentVersion.isNull && currentVersion.get() >= releaseVersion) {
        infoF!"Skipping this version since it's not newer than the current %s."(currentVersion.get);
        return;
    }

    // Find the release's asset, and download it.
    Nullable!JSONValue nullableAsset = findJarAsset(responseJson);
    if (nullableAsset.isNull) {
        warn("Latest release has no asset. Ignoring.");
        return;
    }
    JSONValue asset = nullableAsset.get();
    immutable string filename = asset.object["name"].str;
    immutable string downloadUrl = asset.object["browser_download_url"].str;
    infoF!"Found asset: %s. Downloading from %s."(filename, downloadUrl);
    if (exists(filename)) {
        std.file.remove(filename);
    }

    Request downloadRequest = Request();
    downloadRequest.useStreaming = true;
    Response downloadResponse = downloadRequest.get(downloadUrl);
    File f = File(filename, "wb");
    auto stream = downloadResponse.receiveAsRange();
    while (!stream.empty) {
        f.rawWrite(stream.front);
        stream.popFront();
    }
    f.close();
    infoF!"Downloaded file to %s"(f.name);
}

private Nullable!JSONValue findJarAsset(ref JSONValue response) {
    foreach (JSONValue asset; response.object["assets"].array) {
        immutable string name = asset.object["name"].str;
        if (
            startsWith(name, "materials-extractor") &&
            endsWith(name, ".jar") &&
            asset.object["content_type"].str == "application/java-archive"
        ) {
            return nullable(asset);
        }
    }
    return Nullable!JSONValue.init;
}