using System.Threading;
using Content.Server.Administration.Logs;
using Content.Server.Body.Systems;
using Content.Server.DoAfter;
using Content.Server.Medical.Components;
using Content.Server.Stack;
using Content.Shared.Audio;
using Content.Shared.Damage;
using Content.Shared.Database;
using Content.Shared.Interaction;
using Content.Shared.Interaction.Events;
using Content.Shared.Mobs;
using Content.Shared.Mobs.Components;
using Content.Shared.Mobs.Systems;
using Content.Shared.Stacks;
using Robust.Shared.Random;

namespace Content.Server.Medical;

public sealed class HealingSystem : EntitySystem
{
    [Dependency] private readonly SharedAudioSystem _audio = default!;
    [Dependency] private readonly IAdminLogManager _adminLogger = default!;
    [Dependency] private readonly DamageableSystem _damageable = default!;
    [Dependency] private readonly BloodstreamSystem _bloodstreamSystem = default!;
    [Dependency] private readonly DoAfterSystem _doAfter = default!;
    [Dependency] private readonly IRobustRandom _random = default!;
    [Dependency] private readonly StackSystem _stacks = default!;
    [Dependency] private readonly SharedInteractionSystem _interactionSystem = default!;
    [Dependency] private readonly MobStateSystem _mobStateSystem = default!;
    [Dependency] private readonly MobThresholdSystem _mobThresholdSystem = default!;

    public override void Initialize()
    {
        base.Initialize();
        SubscribeLocalEvent<HealingComponent, UseInHandEvent>(OnHealingUse);
        SubscribeLocalEvent<HealingComponent, AfterInteractEvent>(OnHealingAfterInteract);
        SubscribeLocalEvent<HealingCancelledEvent>(OnHealingCancelled);
        SubscribeLocalEvent<DamageableComponent, HealingCompleteEvent>(OnHealingComplete);
    }

    private void OnHealingComplete(EntityUid uid, DamageableComponent component, HealingCompleteEvent args)
    {
        if (_mobStateSystem.IsDead(uid))
            return;

        if (TryComp<StackComponent>(args.Component.Owner, out var stack) && stack.Count < 1)
            return;

        if (component.DamageContainerID is not null &&
            !component.DamageContainerID.Equals(component.DamageContainerID))
            return;

        if (args.Component.BloodlossModifier != 0)
        {
            // Heal some bloodloss damage.
            _bloodstreamSystem.TryModifyBleedAmount(uid, args.Component.BloodlossModifier);
        }

        var healed = _damageable.TryChangeDamage(uid, args.Component.Damage, true, origin: args.User);

        // Reverify that we can heal the damage.
        if (healed == null)
            return;

        _stacks.Use(args.Component.Owner, 1, stack);

        if (uid != args.User)
            _adminLogger.Add(LogType.Healed, $"{EntityManager.ToPrettyString(args.User):user} healed {EntityManager.ToPrettyString(uid):target} for {healed.Total:damage} damage");
        else
            _adminLogger.Add(LogType.Healed, $"{EntityManager.ToPrettyString(args.User):user} healed themselves for {healed.Total:damage} damage");

        if (args.Component.HealingEndSound != null)
        {
            _audio.PlayPvs(args.Component.HealingEndSound, uid,
                AudioHelpers.WithVariation(0.125f, _random).WithVolume(-5f));
        }
    }

    private static void OnHealingCancelled(HealingCancelledEvent ev)
    {
        ev.Component.CancelToken = null;
    }

    private void OnHealingUse(EntityUid uid, HealingComponent component, UseInHandEvent args)
    {
        if (args.Handled)
            return;

        if (TryHeal(uid, args.User, args.User, component))
            args.Handled = true;
    }

    private void OnHealingAfterInteract(EntityUid uid, HealingComponent component, AfterInteractEvent args)
    {
        if (args.Handled || !args.CanReach || args.Target == null)
            return;

        if (TryHeal(uid, args.User, args.Target.Value, component))
            args.Handled = true;
    }

    private bool TryHeal(EntityUid uid, EntityUid user, EntityUid target, HealingComponent component)
    {
        if (component.CancelToken != null)
        {
            return false;
        }

        if (_mobStateSystem.IsDead(target))
            return false;

        if (!TryComp<DamageableComponent>(target, out var targetDamage))
            return false;

        if (targetDamage.TotalDamage == 0)
            return false;

        if (component.DamageContainerID is not null && !component.DamageContainerID.Equals(targetDamage.DamageContainerID))
            return false;

        if (user != target &&
            !_interactionSystem.InRangeUnobstructed(user, target, popup: true))
        {
            return false;
        }

        if (TryComp<StackComponent>(component.Owner, out var stack) && stack.Count < 1)
            return false;

        component.CancelToken = new CancellationTokenSource();

        if (component.HealingBeginSound != null)
        {
            _audio.PlayPvs(component.HealingBeginSound, uid,
                AudioHelpers.WithVariation(0.125f, _random).WithVolume(-5f));
        }

        var delay = user != target
            ? component.Delay
            : component.Delay * GetScaledHealingPenalty(user, component);

        _doAfter.DoAfter(new DoAfterEventArgs(user, delay, component.CancelToken.Token, target)
        {
            BreakOnUserMove = true,
            BreakOnTargetMove = true,
            // Didn't break on damage as they may be trying to prevent it and
            // not being able to heal your own ticking damage would be frustrating.
            BreakOnStun = true,
            NeedHand = true,
            TargetFinishedEvent = new HealingCompleteEvent
            {
                User = user,
                Component = component,
            },
            BroadcastCancelledEvent = new HealingCancelledEvent
            {
                Component = component,
            },
            // Juusstt in case damageble gets removed it avoids having to re-cancel the token. Won't need this when DoAfterEvent<T> gets added.
            PostCheck = () =>
            {
                component.CancelToken = null;
                return true;
            },
        });

        return true;
    }

    /// <summary>
    /// Scales the self-heal penalty based on the amount of damage taken
    /// </summary>
    /// <param name="uid"></param>
    /// <param name="component"></param>
    /// <returns></returns>
    public float GetScaledHealingPenalty(EntityUid uid, HealingComponent component)
    {
        var output = component.Delay;
        if (!TryComp<MobThresholdsComponent>(uid, out var mobThreshold) || !TryComp<DamageableComponent>(uid, out var damageable))
            return output;


        if (!_mobThresholdSystem.TryGetThresholdForState(uid, MobState.Critical, out var amount,
                mobThreshold))
        {
            return 1;
        }
        var percentDamage = (float) (damageable.TotalDamage / amount);
        //basically make it scale from 1 to the multiplier.
        var modifier = percentDamage * (component.SelfHealPenaltyMultiplier - 1) + 1;
        return Math.Max(modifier, 1);
    }

    private sealed class HealingCompleteEvent : EntityEventArgs
    {
        public EntityUid User;
        public HealingComponent Component = default!;
    }

    private sealed class HealingCancelledEvent : EntityEventArgs
    {
        public HealingComponent Component = default!;
    }
}