import * as blueslip from "./blueslip";
import * as compose_fade from "./compose_fade";
import * as hash_util from "./hash_util";
import * as people from "./people";
import * as presence from "./presence";
import * as timerender from "./timerender";
import * as unread from "./unread";
import * as user_status from "./user_status";
import * as util from "./util";

/*

   This is the main model code for building the buddy list.
   We also rely on presence.js to compute the actual presence
   for users.  We glue in other "people" data and do
   filtering/sorting of the data that we'll send into the view.

*/

export const max_size_before_shrinking = 600;

const fade_config = {
    get_user_id(item) {
        return item.user_id;
    },
    fade(item) {
        item.faded = true;
    },
    unfade(item) {
        item.faded = false;
    },
};

export function get_user_circle_class(user_id) {
    const status = buddy_status(user_id);

    switch (status) {
        case "active":
            return "user_circle_green";
        case "idle":
            return "user_circle_orange";
        case "away_them":
        case "away_me":
            return "user_circle_empty_line";
        default:
            return "user_circle_empty";
    }
}

export function status_description(user_id) {
    const status = buddy_status(user_id);

    switch (status) {
        case "active":
            return i18n.t("Active");
        case "idle":
            return i18n.t("Idle");
        case "away_them":
        case "away_me":
            return i18n.t("Unavailable");
        default:
            return i18n.t("Offline");
    }
}

export function level(user_id) {
    if (people.is_my_user_id(user_id)) {
        // Always put current user at the top.
        return 0;
    }

    const status = buddy_status(user_id);

    switch (status) {
        case "active":
            return 1;
        case "idle":
            return 2;
        case "away_them":
            return 3;
        default:
            return 3;
    }
}

export function buddy_status(user_id) {
    if (user_status.is_away(user_id)) {
        if (people.is_my_user_id(user_id)) {
            return "away_me";
        }

        return "away_them";
    }

    // get active/idle/etc.
    return presence.get_status(user_id);
}

export function compare_function(a, b) {
    const level_a = level(a);
    const level_b = level(b);
    const diff = level_a - level_b;
    if (diff !== 0) {
        return diff;
    }

    // Sort equivalent PM names alphabetically
    const person_a = people.get_by_user_id(a);
    const person_b = people.get_by_user_id(b);

    const full_name_a = person_a ? person_a.full_name : "";
    const full_name_b = person_b ? person_b.full_name : "";

    return util.strcmp(full_name_a, full_name_b);
}

export function sort_users(user_ids) {
    // TODO sort by unread count first, once we support that
    user_ids.sort(compare_function);
    return user_ids;
}

function filter_user_ids(user_filter_text, user_ids) {
    if (user_filter_text === "") {
        return user_ids;
    }

    user_ids = user_ids.filter((user_id) => !people.is_my_user_id(user_id));

    let search_terms = user_filter_text.toLowerCase().split(/[,|]+/);
    search_terms = search_terms.map((s) => s.trim());

    const persons = user_ids.map((user_id) => people.get_by_user_id(user_id));

    const user_id_dict = people.filter_people_by_search_terms(persons, search_terms);
    return Array.from(user_id_dict.keys());
}

export function matches_filter(user_filter_text, user_id) {
    // This is a roundabout way of checking a user if you look
    // too hard at it, but it should be fine for now.
    return filter_user_ids(user_filter_text, [user_id]).length === 1;
}

function get_num_unread(user_id) {
    return unread.num_unread_for_person(user_id.toString());
}

export function get_my_user_status(user_id) {
    if (!people.is_my_user_id(user_id)) {
        return undefined;
    }

    if (user_status.is_away(user_id)) {
        return i18n.t("(unavailable)");
    }

    return i18n.t("(you)");
}

export function user_last_seen_time_status(user_id) {
    const status = presence.get_status(user_id);
    if (status === "active") {
        return i18n.t("Active now");
    }

    if (page_params.realm_is_zephyr_mirror_realm) {
        // We don't send presence data to clients in Zephyr mirroring realms
        return i18n.t("Unknown");
    }

    // There are situations where the client has incomplete presence
    // history on a user.  This can happen when users are deactivated,
    // or when they just haven't been present in a long time (and we
    // may have queries on presence that go back only N weeks).
    //
    // We give the somewhat vague status of "Unknown" for these users.
    const last_active_date = presence.last_active_date(user_id);
    if (last_active_date === undefined) {
        return i18n.t("More than 2 weeks ago");
    }
    return timerender.last_seen_status_from_date(last_active_date);
}

export function info_for(user_id) {
    const user_circle_class = get_user_circle_class(user_id);
    const person = people.get_by_user_id(user_id);
    const my_user_status = get_my_user_status(user_id);
    const user_circle_status = status_description(user_id);

    return {
        href: hash_util.pm_with_uri(person.email),
        name: person.full_name,
        user_id,
        my_user_status,
        is_current_user: people.is_my_user_id(user_id),
        num_unread: get_num_unread(user_id),
        user_circle_class,
        user_circle_status,
    };
}

function get_last_seen(active_status, last_seen) {
    if (active_status === "active") {
        return last_seen;
    }

    const last_seen_text = i18n.t("Last active: __- last_seen__", {last_seen});
    return last_seen_text;
}

export function get_title_data(user_ids_string, is_group) {
    if (is_group === true) {
        // For groups, just return a string with recipient names.
        return {
            first_line: people.get_recipients(user_ids_string),
            second_line: "",
            third_line: "",
        };
    }

    // Since it's not a group, user_ids_string is a single user ID.
    const user_id = Number.parseInt(user_ids_string, 10);
    const person = people.get_by_user_id(user_id);

    if (person.is_bot) {
        const bot_owner = people.get_bot_owner_user(person);

        if (bot_owner) {
            const bot_owner_name = i18n.t("Owner: __name__", {name: bot_owner.full_name});

            return {
                first_line: person.full_name,
                second_line: bot_owner_name,
                third_line: "",
            };
        }

        // Bot does not have an owner.
        return {
            first_line: person.full_name,
            second_line: "",
            third_line: "",
        };
    }

    // For buddy list and individual PMS.  Since is_group=False, it's
    // a single, human, user.
    const active_status = presence.get_status(user_id);
    const last_seen = user_last_seen_time_status(user_id);

    // Users has a status.
    if (user_status.get_status_text(user_id)) {
        return {
            first_line: person.full_name,
            second_line: user_status.get_status_text(user_id),
            third_line: get_last_seen(active_status, last_seen),
        };
    }

    // Users does not have a status.
    return {
        first_line: person.full_name,
        second_line: get_last_seen(active_status, last_seen),
        third_line: "",
    };
}

export function get_item(user_id) {
    const info = info_for(user_id);
    compose_fade.update_user_info([info], fade_config);
    return info;
}

function user_is_recently_active(user_id) {
    // return true if the user has a green/orange circle
    return level(user_id) <= 2;
}

function maybe_shrink_list(user_ids, user_filter_text) {
    if (user_ids.length <= max_size_before_shrinking) {
        return user_ids;
    }

    if (user_filter_text) {
        // If the user types something, we want to show all
        // users matching the text, even if they have not been
        // online recently.
        // For super common letters like "s", we may
        // eventually want to filter down to only users that
        // are in presence.get_user_ids().
        return user_ids;
    }

    user_ids = user_ids.filter((user_id) => user_is_recently_active(user_id));

    return user_ids;
}

function get_user_id_list(user_filter_text) {
    let user_ids;

    if (user_filter_text) {
        // If there's a filter, select from all users, not just those
        // recently active.
        user_ids = filter_user_ids(user_filter_text, people.get_active_user_ids());
    } else {
        // From large realms, the user_ids in presence may exclude
        // users who have been idle more than three weeks.  When the
        // filter text is blank, we show only those recently active users.
        user_ids = presence.get_user_ids();
    }

    user_ids = user_ids.filter((user_id) => {
        const person = people.get_by_user_id(user_id);

        if (!person) {
            blueslip.warn("Got user_id in presence but not people: " + user_id);
            return false;
        }

        // if the user is bot, do not show in presence data.
        return !person.is_bot;
    });
    return user_ids;
}

export function get_filtered_and_sorted_user_ids(user_filter_text) {
    let user_ids;
    user_ids = get_user_id_list(user_filter_text);
    user_ids = maybe_shrink_list(user_ids, user_filter_text);
    return sort_users(user_ids);
}

export function get_items_for_users(user_ids) {
    const user_info = user_ids.map((user_id) => info_for(user_id));
    compose_fade.update_user_info(user_info, fade_config);
    return user_info;
}

export function huddle_fraction_present(huddle) {
    const user_ids = huddle.split(",").map((s) => Number.parseInt(s, 10));

    let num_present = 0;

    for (const user_id of user_ids) {
        if (presence.is_active(user_id)) {
            num_present += 1;
        }
    }

    if (num_present === user_ids.length) {
        return 1;
    } else if (num_present !== 0) {
        return 0.5;
    }
    return undefined;
}