namespace Aeshnidae.InstancesNoDat;

/// <summary>
/// The line a player reads on stepping into a copy: what tier it is and what that
/// means, in numbers (Tom, 2026-09-19: "the arrival line is a go"). Sent once per
/// crossing, from the physics relocation that is the moment the player is really
/// inside. Other mods with something to add about the place - what its loot does -
/// hang a handler on <see cref="OnArrival"/>; Aeshnidae.AwakenedRewards binds to it
/// by reflection, so neither mod references the other.
/// </summary>
public static class Arrival
{
    /// <summary>(player, landblock, copy, tier) - fired after this mod's own line.</summary>
    public static Action<Player, ushort, int, int>? OnArrival;

    public static void Announce(Player player, ushort landblock, int copy)
    {
        try
        {
            if (player?.Session is null)
                return;

            var settings = Mod.Settings;
            var name = Mod.NameFor(landblock);
            var scope = Mod.ScopeOf(landblock, copy);

            // A personal copy is a solo place, and a fellowship shares experience across
            // the whole server: a character in one would take shares from fellows in
            // other copies, or hand its tier-scaled kills out to them (Tom, 2026-09-19).
            // So stepping into a personal copy is leaving the fellowship.
            if (settings.LeaveFellowshipOnEntry && scope == InstanceScope.Personal && player.Fellowship is not null)
            {
                var fellowship = player.Fellowship.FellowshipName;
                player.FellowshipQuit(false);
                player.SendMessage($"You leave {fellowship}: {name} is yours alone, and a fellowship shares experience across the whole server.");
                Mod.Trace($"{player.Name} left fellowship '{fellowship}' on entering copy {copy} of {landblock:X4}");
            }

            if (!settings.AnnounceArrival)
                return;
            var tier = Scaling.TierFor(landblock, copy);

            if (Enclaves.IsEnclaveCopy(copy))
            {
                // The owning mod says what this place is (Towns: whose town); nothing from here.
            }
            else if (Variants.ChosenFor(landblock, copy) is { Unscaled: true })
            {
                // Same rule: the filling was supplied by another mod, so its difficulty is
                // not this mod's tier and "tier 0, stock monsters" would be a wrong line
                // (Aeshnidae.Challenge: a roster drawn from a score band). It says what the
                // place is, on the hook below.
            }
            else if (Worlds.IsWorldCopy(copy))
            {
                // One line per arrival by teleport (a portal, a recall); walking between
                // landblocks of the world's outdoors never comes here.
                player.SendMessage(Worlds.Describe(Worlds.TierOfCopy(copy)));
            }
            else if (tier <= 0)
            {
                player.SendMessage(scope == InstanceScope.Shared
                    ? $"{name}: one room for everyone on the server, stock difficulty."
                    : $"{name}, tier 0: your own copy, stock monsters, stock rewards.");
            }
            else
            {
                var harder = settings.DifficultyPercentPerEnlightenment * tier;
                var richer = settings.RewardPercentPerEnlightenment * tier;

                player.SendMessage($"{name}, tier {tier}: your own copy. Monsters +{harder:0.#}% (attributes on the tier-built ones; skills, health and damage on the rest), rewards +{richer:0.#}% experience and luminance.");
            }

            OnArrival?.Invoke(player, landblock, copy, tier);
        }
        catch (Exception ex)
        {
            ModManager.Log($"[{Mod.Name}] arrival line failed: {ex.Message}", ModManager.LogLevel.Warn);
        }
    }
}