using Gee;

using Xmpp;
using Xmpp.Xep;
using Dino.Entities;
using Qlite;

public class Dino.HistorySync {

    private StreamInteractor stream_interactor;
    private Database db;

    public HashMap<Account, HashMap<Jid, int>> current_catchup_id = new HashMap<Account, HashMap<Jid, int>>(Account.hash_func, Account.equals_func);
    public HashMap<Account, HashMap<string, DateTime>> mam_times = new HashMap<Account, HashMap<string, DateTime>>();
    public HashMap<string, int> hitted_range = new HashMap<string, int>();

    // Server ID of the latest message of the previous segment
    public HashMap<Account, string> catchup_until_id = new HashMap<Account, string>(Account.hash_func, Account.equals_func);
    // Time of the latest message of the previous segment
    public HashMap<Account, DateTime> catchup_until_time = new HashMap<Account, DateTime>(Account.hash_func, Account.equals_func);

    private HashMap<string, Gee.List<Xmpp.MessageStanza>> stanzas = new HashMap<string, Gee.List<Xmpp.MessageStanza>>();

    public class HistorySync(Database db, StreamInteractor stream_interactor) {
        this.stream_interactor = stream_interactor;
        this.db = db;

        stream_interactor.account_added.connect(on_account_added);

        stream_interactor.connection_manager.stream_opened.connect((account, stream) => {
            debug("MAM: [%s] Reset catchup_id", account.bare_jid.to_string());
            current_catchup_id.unset(account);
        });
    }

    public bool process(Account account, Xmpp.MessageStanza message_stanza) {
        var mam_flag = Xmpp.MessageArchiveManagement.MessageFlag.get_flag(message_stanza);

        if (mam_flag != null) {
            process_mam_message(account, message_stanza, mam_flag);
            return true;
        } else {
            update_latest_db_range(account, message_stanza);
            return false;
        }
    }

    public void update_latest_db_range(Account account, Xmpp.MessageStanza message_stanza) {
        Jid mam_server = stream_interactor.get_module(MucManager.IDENTITY).might_be_groupchat(message_stanza.from.bare_jid, account) ? message_stanza.from.bare_jid : account.bare_jid;

        if (!current_catchup_id.has_key(account) || !current_catchup_id[account].has_key(mam_server)) return;

        string? stanza_id = UniqueStableStanzaIDs.get_stanza_id(message_stanza, mam_server);
        if (stanza_id == null) return;

        db.mam_catchup.update()
                .with(db.mam_catchup.id, "=", current_catchup_id[account][mam_server])
                .set(db.mam_catchup.to_time, (long)new DateTime.now_utc().to_unix())
                .set(db.mam_catchup.to_id, stanza_id)
                .perform();
    }

    public void process_mam_message(Account account, Xmpp.MessageStanza message_stanza, Xmpp.MessageArchiveManagement.MessageFlag mam_flag) {
        Jid mam_server = mam_flag.sender_jid;
        Jid message_author = message_stanza.from;

        // MUC servers may only send MAM messages from that MUC
        bool is_muc_mam = stream_interactor.get_module(MucManager.IDENTITY).might_be_groupchat(mam_server, account) &&
                message_author.equals_bare(mam_server);

        bool from_our_server = mam_server.equals_bare(account.bare_jid);

        if (!is_muc_mam && !from_our_server) {
            warning("Received alleged MAM message from %s, ignoring", mam_server.to_string());
            return;
        }

        if (!stanzas.has_key(mam_flag.query_id)) stanzas[mam_flag.query_id] = new ArrayList<Xmpp.MessageStanza>();
        stanzas[mam_flag.query_id].add(message_stanza);
    }

    private void on_unprocessed_message(Account account, XmppStream stream, MessageStanza message) {
        // Check that it's a legit MAM server
        bool is_muc_mam = stream_interactor.get_module(MucManager.IDENTITY).might_be_groupchat(message.from, account);
        bool from_our_server = message.from.equals_bare(account.bare_jid);
        if (!is_muc_mam && !from_our_server) return;

        // Get the server time of the message and store it in `mam_times`
        Xmpp.MessageArchiveManagement.Flag? mam_flag = stream != null ? stream.get_flag(Xmpp.MessageArchiveManagement.Flag.IDENTITY) : null;
        if (mam_flag == null) return;
        string? id = message.stanza.get_deep_attribute(mam_flag.ns_ver + ":result", "id");
        if (id == null) return;
        StanzaNode? delay_node = message.stanza.get_deep_subnode(mam_flag.ns_ver + ":result", StanzaForwarding.NS_URI + ":forwarded", DelayedDelivery.NS_URI + ":delay");
        if (delay_node == null) {
            warning("MAM result did not contain delayed time %s", message.stanza.to_string());
            return;
        }
        DateTime? time = DelayedDelivery.get_time_for_node(delay_node);
        if (time == null) return;
        mam_times[account][id] = time;

        // Check if this is the target message
        string? query_id = message.stanza.get_deep_attribute(mam_flag.ns_ver + ":result", mam_flag.ns_ver + ":queryid");
        if (query_id != null && id == catchup_until_id[account]) {
            debug("[%s] Hitted range (id) %s", account.bare_jid.to_string(), id);
            hitted_range[query_id] = -2;
        }
    }

    public void on_server_id_duplicate(Account account, Xmpp.MessageStanza message_stanza, Entities.Message message) {
        Xmpp.MessageArchiveManagement.MessageFlag? mam_flag = Xmpp.MessageArchiveManagement.MessageFlag.get_flag(message_stanza);
        if (mam_flag == null) return;

//        debug(@"MAM: [%s] Hitted range duplicate server id. id %s qid %s", account.bare_jid.to_string(), message.server_id, mam_flag.query_id);
        if (catchup_until_time.has_key(account) && mam_flag.server_time.compare(catchup_until_time[account]) < 0) {
            hitted_range[mam_flag.query_id] = -1;
//            debug(@"MAM: [%s] In range (time) %s < %s", account.bare_jid.to_string(), mam_flag.server_time.to_string(), catchup_until_time[account].to_string());
        }
    }

    public async void fetch_everything(Account account, Jid mam_server, DateTime until_earliest_time = new DateTime.from_unix_utc(0)) {
        debug("Fetch everything for %s %s", mam_server.to_string(), until_earliest_time != null ? @"(until $until_earliest_time)" : "");
        RowOption latest_row_opt = db.mam_catchup.select()
                .with(db.mam_catchup.account_id, "=", account.id)
                .with(db.mam_catchup.server_jid, "=", mam_server.to_string())
                .with(db.mam_catchup.to_time, ">=", (long) until_earliest_time.to_unix())
                .order_by(db.mam_catchup.to_time, "DESC")
                .single().row();
        Row? latest_row = latest_row_opt.is_present() ? latest_row_opt.inner : null;

        Row? new_row = yield fetch_latest_page(account, mam_server, latest_row, until_earliest_time);

        if (new_row != null) {
            current_catchup_id[account][mam_server] = new_row[db.mam_catchup.id];
        } else if (latest_row != null) {
            current_catchup_id[account][mam_server] = latest_row[db.mam_catchup.id];
        }

        // Set the previous and current row
        Row? previous_row = null;
        Row? current_row = null;
        if (new_row != null) {
            current_row = new_row;
            previous_row = latest_row;
        } else if (latest_row != null) {
            current_row = latest_row;
            RowOption previous_row_opt = db.mam_catchup.select()
                    .with(db.mam_catchup.account_id, "=", account.id)
                    .with(db.mam_catchup.server_jid, "=", mam_server.to_string())
                    .with(db.mam_catchup.to_time, "<", current_row[db.mam_catchup.from_time])
                    .with(db.mam_catchup.to_time, ">=", (long) until_earliest_time.to_unix())
                    .order_by(db.mam_catchup.to_time, "DESC")
                    .single().row();
            previous_row = previous_row_opt.is_present() ? previous_row_opt.inner : null;
        }

        // Fetch messages between two db ranges and merge them
        while (current_row != null && previous_row != null) {
            if (current_row[db.mam_catchup.from_end]) return;

            debug("[%s] Fetching between ranges %s - %s", mam_server.to_string(), previous_row[db.mam_catchup.to_time].to_string(), current_row[db.mam_catchup.from_time].to_string());
            current_row = yield fetch_between_ranges(account, mam_server, previous_row, current_row);
            if (current_row == null) return;

            RowOption previous_row_opt = db.mam_catchup.select()
                    .with(db.mam_catchup.account_id, "=", account.id)
                    .with(db.mam_catchup.server_jid, "=", mam_server.to_string())
                    .with(db.mam_catchup.to_time, "<", current_row[db.mam_catchup.from_time])
                    .with(db.mam_catchup.to_time, ">=", (long) until_earliest_time.to_unix())
                    .order_by(db.mam_catchup.to_time, "DESC")
                    .single().row();
            previous_row = previous_row_opt.is_present() ? previous_row_opt.inner : null;
        }

        // We're at the earliest range. Try to expand it even further back.
        if (current_row == null || current_row[db.mam_catchup.from_end]) return;
        // We don't want to fetch before the earliest range over and over again in MUCs if it's after until_earliest_time.
        // For now, don't query if we are within a week of until_earliest_time
        if (until_earliest_time != null &&
                current_row[db.mam_catchup.from_time] > until_earliest_time.add(-TimeSpan.DAY * 7).to_unix()) return;
        yield fetch_before_range(account, mam_server, current_row, until_earliest_time);
    }

    // Fetches the latest page (up to previous db row). Extends the previous db row if it was reached, creates a new row otherwise.
    public async Row? fetch_latest_page(Account account, Jid mam_server, Row? latest_row, DateTime? until_earliest_time) {
        debug("[%s | %s] Fetching latest page", account.bare_jid.to_string(), mam_server.to_string());

        int latest_row_id = -1;
        DateTime latest_message_time = until_earliest_time;
        string? latest_message_id = null;

        if (latest_row != null) {
            latest_row_id = latest_row[db.mam_catchup.id];
            latest_message_time = (new DateTime.from_unix_utc(latest_row[db.mam_catchup.to_time])).add_minutes(-5);
            latest_message_id = latest_row[db.mam_catchup.to_id];

            // Make sure we only fetch to until_earliest_time if latest_message_time is further back
            if (until_earliest_time != null && latest_message_time.compare(until_earliest_time) < 0) {
                latest_message_time = until_earliest_time.add_minutes(-5);
                latest_message_id = null;
            }
        }

        var query_params = new Xmpp.MessageArchiveManagement.V2.MamQueryParams.query_latest(mam_server, latest_message_time, latest_message_id);

        PageRequestResult page_result = yield get_mam_page(account, query_params, null);

        if (page_result.page_result == PageResult.Duplicate) {
            // No new messages
            return null;
        }

        if (page_result.page_result == PageResult.Error) {
            debug("[%s | %s] Failed fetching latest page %s", mam_server.to_string(), mam_server.to_string(), page_result.page_result.to_string());
            return null;
        }

        // Catchup finished within first page. Update latest db entry.
        if (page_result.page_result in new PageResult[] { PageResult.TargetReached, PageResult.NoMoreMessages } && latest_row_id != -1) {
            if (page_result.stanzas == null || page_result.stanzas.is_empty) return null;

            string latest_mam_id = page_result.query_result.last;
            long latest_mam_time = (long) mam_times[account][latest_mam_id].to_unix();

            var query = db.mam_catchup.update()
                    .with(db.mam_catchup.id, "=", latest_row_id)
                    .set(db.mam_catchup.to_time, latest_mam_time)
                    .set(db.mam_catchup.to_id, latest_mam_id);

            if (page_result.page_result == PageResult.NoMoreMessages) {
                // If the server doesn't have more messages, store that this range is at its end.
                query.set(db.mam_catchup.from_end, true);
            }
            query.perform();
            return null;
        }

        if (page_result.query_result.first == null || page_result.query_result.last == null) {
            return null;
        }

        // Either we need to fetch more pages or this is the first db entry ever
        debug("[%s | %s] Creating new db range for latest page", mam_server.to_string(), mam_server.to_string());

        string from_id = page_result.query_result.first;
        string to_id = page_result.query_result.last;

        if (!mam_times[account].has_key(from_id) || !mam_times[account].has_key(to_id)) {
            debug("Missing from/to id %s %s", from_id, to_id);
            return null;
        }

        long from_time = (long) mam_times[account][from_id].to_unix();
        long to_time = (long) mam_times[account][to_id].to_unix();

        int new_row_id = (int) db.mam_catchup.insert()
                .value(db.mam_catchup.account_id, account.id)
                .value(db.mam_catchup.server_jid, mam_server.to_string())
                .value(db.mam_catchup.from_id, from_id)
                .value(db.mam_catchup.from_time, from_time)
                .value(db.mam_catchup.from_end, false)
                .value(db.mam_catchup.to_id, to_id)
                .value(db.mam_catchup.to_time, to_time)
                .perform();
        return db.mam_catchup.select().with(db.mam_catchup.id, "=", new_row_id).single().row().inner;
    }

    /** Fetches messages between the end of `earlier_range` and start of `later_range`
     ** Merges the `earlier_range` db row into the `later_range` db row.
     ** @return The resulting range comprising `earlier_range`, `later_rage`, and everything in between. null if fetching/merge failed.
     **/
    private async Row? fetch_between_ranges(Account account, Jid mam_server, Row earlier_range, Row later_range) {
        int later_range_id = (int) later_range[db.mam_catchup.id];
        DateTime earliest_time = new DateTime.from_unix_utc(earlier_range[db.mam_catchup.to_time]);
        DateTime latest_time = new DateTime.from_unix_utc(later_range[db.mam_catchup.from_time]);
        debug("[%s | %s] Fetching between %s (%s) and %s (%s)", account.bare_jid.to_string(), mam_server.to_string(), earliest_time.to_string(), earlier_range[db.mam_catchup.to_id], latest_time.to_string(), later_range[db.mam_catchup.from_id]);

        var query_params = new Xmpp.MessageArchiveManagement.V2.MamQueryParams.query_between(mam_server,
            earliest_time, earlier_range[db.mam_catchup.to_id],
            latest_time, later_range[db.mam_catchup.from_id]);

        PageRequestResult page_result = yield fetch_query(account, query_params, later_range_id);

        if (page_result.page_result == PageResult.TargetReached) {
            debug("[%s | %s] Merging range %i into %i", account.bare_jid.to_string(), mam_server.to_string(), earlier_range[db.mam_catchup.id], later_range_id);
            // Merge earlier range into later one.
            db.mam_catchup.update()
                .with(db.mam_catchup.id, "=", later_range_id)
                .set(db.mam_catchup.from_time, earlier_range[db.mam_catchup.from_time])
                .set(db.mam_catchup.from_id, earlier_range[db.mam_catchup.from_id])
                .set(db.mam_catchup.from_end, earlier_range[db.mam_catchup.from_end])
                .perform();

            db.mam_catchup.delete().with(db.mam_catchup.id, "=", earlier_range[db.mam_catchup.id]).perform();

            // Return the updated version of the later range
            return db.mam_catchup.select().with(db.mam_catchup.id, "=", later_range_id).single().row().inner;
        }

        return null;
    }

    private async void fetch_before_range(Account account, Jid mam_server, Row range, DateTime? until_earliest_time) {
        DateTime latest_time = new DateTime.from_unix_utc(range[db.mam_catchup.from_time]);
        string latest_id = range[db.mam_catchup.from_id];
        debug("[%s | %s] Fetching before range < %s, %s", account.bare_jid.to_string(), mam_server.to_string(), latest_time.to_string(), latest_id);

        Xmpp.MessageArchiveManagement.V2.MamQueryParams query_params;
        if (until_earliest_time == null) {
            query_params = new Xmpp.MessageArchiveManagement.V2.MamQueryParams.query_before(mam_server, latest_time, latest_id);
        } else {
            query_params = new Xmpp.MessageArchiveManagement.V2.MamQueryParams.query_between(
                    mam_server,
                    until_earliest_time, null,
                    latest_time, latest_id
            );
        }
        PageRequestResult page_result = yield fetch_query(account, query_params, range[db.mam_catchup.id]);
    }

    /**
     * Iteratively fetches all pages returned for a query (until a PageResult other than MorePagesAvailable is returned)
     * @return The last PageRequestResult result
     **/
    private async PageRequestResult fetch_query(Account account, Xmpp.MessageArchiveManagement.V2.MamQueryParams query_params, int db_id) {
        debug("[%s | %s] Fetch query %s - %s", account.bare_jid.to_string(), query_params.mam_server.to_string(), query_params.start != null ? query_params.start.to_string() : "", query_params.end != null ? query_params.end.to_string() : "");
        PageRequestResult? page_result = null;
        do {
            page_result = yield get_mam_page(account, query_params, page_result);
            debug("Page result %s %b", page_result.page_result.to_string(), page_result.stanzas == null);

            if (page_result.page_result == PageResult.Error || page_result.stanzas == null) return page_result;

            string earliest_mam_id = page_result.query_result.first;
            long earliest_mam_time = (long)mam_times[account][earliest_mam_id].to_unix();

            debug("Updating %s to %s, %s", query_params.mam_server.to_string(), earliest_mam_time.to_string(), earliest_mam_id);
            var query = db.mam_catchup.update()
                    .with(db.mam_catchup.id, "=", db_id)
                    .set(db.mam_catchup.from_time, earliest_mam_time)
                    .set(db.mam_catchup.from_id, earliest_mam_id);

            if (page_result.page_result == PageResult.NoMoreMessages) {
                // If the server doesn't have more messages, store that this range is at its end.
                query.set(db.mam_catchup.from_end, true);
            }
            query.perform();
        } while (page_result.page_result == PageResult.MorePagesAvailable);

        return page_result;
    }

    enum PageResult {
        MorePagesAvailable,
        TargetReached,
        NoMoreMessages,
        Duplicate,
        Error
    }

    /**
     * prev_page_result: null if this is the first page request
     **/
    private async PageRequestResult get_mam_page(Account account, Xmpp.MessageArchiveManagement.V2.MamQueryParams query_params, PageRequestResult? prev_page_result) {
        XmppStream stream = stream_interactor.get_stream(account);
        Xmpp.MessageArchiveManagement.QueryResult query_result = null;
        if (prev_page_result == null) {
            query_result = yield Xmpp.MessageArchiveManagement.V2.query_archive(stream, query_params);
        } else {
            query_result = yield Xmpp.MessageArchiveManagement.V2.page_through_results(stream, query_params, prev_page_result.query_result);
        }
        return yield process_query_result(account, query_params, query_result);
    }

    private async PageRequestResult process_query_result(Account account, Xmpp.MessageArchiveManagement.V2.MamQueryParams query_params, Xmpp.MessageArchiveManagement.QueryResult query_result) {
        PageResult page_result = PageResult.MorePagesAvailable;

        if (query_result.malformed || query_result.error) {
            page_result = PageResult.Error;
        }

        // We wait until all the messages from the page are processed (and we got the `mam_times` from them)
        Idle.add(process_query_result.callback, Priority.LOW);
        yield;

        // We might have successfully reached the target or the server doesn't have all messages stored anymore
        // If it's the former, we'll overwrite the value with PageResult.MorePagesAvailable below.
        if (query_result.complete) {
            page_result = PageResult.NoMoreMessages;
        }

        string selection = null;
        string[] selection_args = {};

        string query_id = query_params.query_id;
        string? after_id = query_params.start_id;

        // Check the server id of all returned messages. Check if we've hit our target (from_id) or got a duplicate.
        if (stanzas.has_key(query_id) && !stanzas[query_id].is_empty) {
            foreach (Xmpp.MessageStanza message in stanzas[query_id]) {
                Xmpp.MessageArchiveManagement.MessageFlag? mam_message_flag = Xmpp.MessageArchiveManagement.MessageFlag.get_flag(message);
                if (mam_message_flag != null && mam_message_flag.mam_id != null) {
                    if (after_id != null && mam_message_flag.mam_id == after_id) {
                        // Successfully fetched the whole range
                        page_result = PageResult.TargetReached;
                    }

                    if (selection == null) {
                        selection = @"$(db.message.server_id) = ?";
                    } else {
                        selection += @" OR $(db.message.server_id) = ?";
                    }
                    selection_args += mam_message_flag.mam_id;
                }
            }

            if (hitted_range.has_key(query_id)) {
                // Message got filtered out by xmpp-vala, but succesfull range fetch nevertheless
                page_result = PageResult.TargetReached;
            }

            // Check for duplicates among the messages of the page.
            var duplicates_qry = db.message.select()
                    .with(db.message.account_id, "=", account.id)
                    .where(selection, selection_args);
            // We don't want messages from different MAM servers to interfere with each other.
            if (!query_params.mam_server.equals_bare(account.bare_jid)) {
                duplicates_qry.with(db.message.counterpart_id, "=", db.get_jid_id(query_params.mam_server));
            } else {
                duplicates_qry.with(db.message.type_, "=", Message.Type.CHAT);
            }
            var duplicates_count = duplicates_qry.count();
            if (duplicates_count > 0) {
                // We got a duplicate although we thought we have to catch up.
                // There was a server bug where prosody would send all messages if it didn't know the after ID that was given
                page_result = PageResult.Duplicate;
            }
        }

        var res = new PageRequestResult() { stanzas=stanzas[query_id], page_result=page_result, query_result=query_result };
        send_messages_back_into_pipeline(account, query_id);
        return res;
    }

    private void send_messages_back_into_pipeline(Account account, string query_id) {
        if (!stanzas.has_key(query_id)) return;

        foreach (Xmpp.MessageStanza message in stanzas[query_id]) {
            stream_interactor.get_module(MessageProcessor.IDENTITY).run_pipeline_announce.begin(account, message);
        }
        stanzas.unset(query_id);
    }

    private void on_account_added(Account account) {
        cleanup_db_ranges(db, account);

        mam_times[account] = new HashMap<string, DateTime>();

        XmppStream? stream_bak = null;
        stream_interactor.module_manager.get_module(account, Xmpp.MessageArchiveManagement.Module.IDENTITY).feature_available.connect( (stream) => {
            if (stream == stream_bak) return;

            current_catchup_id[account] = new HashMap<Jid, int>(Jid.hash_func, Jid.equals_func);
            stream_bak = stream;
            debug("[%s] MAM available", account.bare_jid.to_string());
            fetch_everything.begin(account, account.bare_jid);
        });

        stream_interactor.module_manager.get_module(account, Xmpp.MessageModule.IDENTITY).received_message_unprocessed.connect((stream, message) => {
            on_unprocessed_message(account, stream, message);
        });
    }

    public static void cleanup_db_ranges(Database db, Account account) {
        var ranges = new HashMap<Jid, ArrayList<MamRange>>(Jid.hash_func, Jid.equals_func);
        foreach (Row row in db.mam_catchup.select().with(db.mam_catchup.account_id, "=", account.id)) {
            var mam_range = new MamRange();
            mam_range.id = row[db.mam_catchup.id];
            mam_range.server_jid = new Jid(row[db.mam_catchup.server_jid]);
            mam_range.from_time = row[db.mam_catchup.from_time];
            mam_range.from_id = row[db.mam_catchup.from_id];
            mam_range.from_end = row[db.mam_catchup.from_end];
            mam_range.to_time = row[db.mam_catchup.to_time];
            mam_range.to_id = row[db.mam_catchup.to_id];

            if (!ranges.has_key(mam_range.server_jid)) ranges[mam_range.server_jid] = new ArrayList<MamRange>();
            ranges[mam_range.server_jid].add(mam_range);
        }

        var to_delete = new ArrayList<MamRange>();

        foreach (Jid server_jid in ranges.keys) {
            foreach (var range1 in ranges[server_jid]) {
                if (to_delete.contains(range1)) continue;

                foreach (MamRange range2 in ranges[server_jid]) {
                    debug("[%s | %s] | %s - %s vs %s - %s", account.bare_jid.to_string(), server_jid.to_string(), range1.from_time.to_string(), range1.to_time.to_string(), range2.from_time.to_string(), range2.to_time.to_string());
                    if (range1 == range2 || to_delete.contains(range2)) continue;

                    // Check if range2 is a subset of range1
                    // range1: #####################
                    // range2:         ######
                    if (range1.from_time <= range2.from_time && range1.to_time >= range2.to_time) {
                        critical("Removing db range which is a subset of another one");
                        to_delete.add(range2);
                        continue;
                    }

                    // Check if range2 is an extension of range1 (towards earlier)
                    // range1:        #####################
                    // range2: ###############
                    if (range1.from_time <= range2.from_time <= range1.to_time && range1.to_time < range2.to_time) {
                        critical("Removing db range that overlapped another one (towards earlier)");
                        db.mam_catchup.update()
                                .with(db.mam_catchup.id, "=", range1.id)
                                .set(db.mam_catchup.from_id, range2.to_id)
                                .set(db.mam_catchup.from_time, range2.to_time)
                                .set(db.mam_catchup.from_end, range2.from_end)
                                .perform();
                        to_delete.add(range2);
                        continue;
                    }

                    // Check if range2 is an extension of range1 (towards more current)
                    // range1: #####################
                    // range2:             ###############
                    if (range1.from_time <= range2.from_time <= range1.to_time && range1.to_time < range2.to_time) {
                        critical("Removing db range that overlapped another one (towards more current)");
                        db.mam_catchup.update()
                                .with(db.mam_catchup.id, "=", range1.id)
                                .set(db.mam_catchup.to_id, range2.to_id)
                                .set(db.mam_catchup.to_time, range2.to_time)
                                .perform();
                        to_delete.add(range2);
                        continue;
                    }
                }
            }
        }

        foreach (MamRange row in to_delete) {
            db.mam_catchup.delete().with(db.mam_catchup.id, "=", row.id).perform();
        }
    }

    class MamRange {
        public int id;
        public Jid server_jid;
        public long from_time;
        public string from_id;
        public bool from_end;
        public long to_time;
        public string to_id;
    }

    class PageRequestResult {
        public Gee.List<MessageStanza> stanzas { get; set; }
        public PageResult page_result { get; set; }
        public Xmpp.MessageArchiveManagement.QueryResult query_result { get; set; }
    }
}