using RPGCore.Core.Objects;
using RPGCore.Stats.ObjectModules.StatsObjectModule.Events;
using RPGCoreCommon.DynamicValues;

namespace RPGCore.Stats.ObjectModules.StatsObjectModule
{
    /// <summary>
    /// <b>You should never instantiate this by yourself!</b>
    /// Instantiated automatically by <see cref="StatsModule"/> for every available <see cref="StatValueDefinitionSO"/>.
    /// </summary>
    public sealed class StatValue
    {
        public readonly StatValueDefinitionSO definition;
        public readonly BaseObject obj;
        public readonly DynamicValueSourceContext sources = new();
        public readonly StatModifierContext modifiers = new();
        
        /// <summary>
        /// Base value defined in <see cref="StatsModule"/> attached to <see cref="BaseObject"/>.
        /// Formula result will be added to this base value.
        /// Default base value is ZERO.
        /// </summary>
        public int baseValue { get; private set; }
        
        /// <summary>
        /// This value is calculated by <see cref="DynamicValue"/> in <see cref="StatValueDefinitionSO"/>
        /// </summary>
        public int value { get; private set; }

        internal StatValue(StatValueDefinitionSO definition, int baseValue, BaseObject obj)
        {
            this.definition = definition;
            this.obj = obj;
            this.baseValue = baseValue;
        }

        /// <summary>
        /// Refreshes <see cref="value"/>, by calculating formula again.
        /// </summary>
        internal void Refresh()
        {
            var previous = value;
            value = definition.dynamicValue.GetValue(sources);
            if (previous == value) return;
            obj.events.Invoke(new StatValueChangeEvent
            {
                after = value,
                before = previous,
                valueDefinition = definition,
                target = obj
            });
        }

        /// <summary>
        /// Sets new <see cref="baseValue"/> and then do <see cref="Refresh"/> to recalculate whole <see cref="value"/>
        /// </summary>
        /// <param name="amount">New base value</param>
        public void SetBase(int amount)
        {
            if (baseValue == amount) return;
            baseValue = amount;
            Refresh();
        }
    }
}