using System;
using System.Reflection;
using UnityEngine;

namespace Unity.VisualScripting
{
    public abstract class PluginConfigurationItemMetadata : Metadata
    {
        public enum Mode
        {
            Field,
            Property
        }

        protected PluginConfigurationItemMetadata(PluginConfiguration configuration, MemberInfo member, Metadata parent) : base(member.Name, parent)
        {
            if (configuration == null)
            {
                throw new ArgumentNullException(nameof(configuration));
            }

            if (!(member is FieldInfo || member is PropertyInfo))
            {
                throw new ArgumentException($"Configuration item '{member.Name}' is not a field or property.", nameof(member));
            }

            if (!member.DeclaringType.IsInstanceOfType(configuration))
            {
                throw new ArgumentException($"Configuration item '{member.Name}' is not declared in '{configuration.GetType().CSharpName()}'.", nameof(member));
            }

            this.configuration = configuration;
            this.member = member;

            attribute = member.GetAttribute<PluginConfigurationItemAttribute>();

            if (attribute == null)
            {
                throw new ArgumentException($"Configuration item '{member.Name}' is missing the [{nameof(PluginConfigurationItemAttribute)}].", nameof(member));
            }

            key = attribute.key ?? member.Name;

            if (member is FieldInfo info)
            {
                mode = Mode.Field;
                fieldInfo = info;
                definedType = fieldInfo.FieldType;
            }
            else // if (memberInfo is PropertyInfo)
            {
                mode = Mode.Property;
                propertyInfo = (PropertyInfo)member;
                definedType = propertyInfo.PropertyType;
            }

            defaultValue = Clone(value);
            label = new GUIContent(member.HumanName(), member.Summary());

            XmlDocumentation.loadComplete += () =>
            {
                label.tooltip = member.Summary();
            };

            if (exists)
            {
                Load();
            }
            else
            {
                value = Clone(defaultValue);
            }
        }

        static object Clone(object source)
        {
            var cloner = Cloning.GetCloner(source, source.GetType());
            return cloner == null ? source : source.Clone(cloner, true);
        }

        public MemberInfo member { get; }
        private FieldInfo fieldInfo { get; }
        private PropertyInfo propertyInfo { get; }
        private Mode mode { get; }

        private PluginConfigurationItemAttribute attribute { get; }

        public string key { get; }
        public object defaultValue { get; set; }
        public PluginConfiguration configuration { get; }

        public bool visible => AttributeUtility.CheckCondition(configuration, attribute.visibleCondition, attribute.visible);
        public bool enabled => AttributeUtility.CheckCondition(configuration, attribute.enabledCondition, attribute.enabled);
        public bool resettable => AttributeUtility.CheckCondition(configuration, attribute.resettableCondition, attribute.resettable);

        public override bool isEditable
        {
            get => enabled;
            set { }
        }

        public abstract bool exists { get; }

        protected override object rawValue
        {
            // Small optimization:
            // To reduce initialization time, we'll use standard
            // reflection for the value if the plugin container isn't
            // initialized yet, which makes sure we don't do an
            // expensive caching or code emission in the first frame.

            get
            {
                switch (mode)
                {
                    case Mode.Field:
                        if (PluginContainer.initialized)
                        {
                            return fieldInfo.GetValueOptimized(configuration);
                        }
                        else
                        {
                            return fieldInfo.GetValue(configuration);
                        }

                    case Mode.Property:
                        if (PluginContainer.initialized)
                        {
                            return propertyInfo.GetValueOptimized(configuration);
                        }
                        else
                        {
                            return propertyInfo.GetValue(configuration, null);
                        }

                    default:
                        throw new UnexpectedEnumValueException<Mode>(mode);
                }
            }
            set
            {
                switch (mode)
                {
                    case Mode.Field:
                        if (PluginContainer.initialized)
                        {
                            fieldInfo.SetValueOptimized(configuration, value);
                        }
                        else
                        {
                            fieldInfo.SetValue(configuration, value);
                        }

                        break;

                    case Mode.Property:
                        if (PluginContainer.initialized)
                        {
                            propertyInfo.SetValueOptimized(configuration, value);
                        }
                        else
                        {
                            propertyInfo.SetValue(configuration, value, null);
                        }

                        break;

                    default:
                        throw new UnexpectedEnumValueException<Mode>(mode);
                }
            }
        }

        public abstract void Load();

        public abstract void Save();

        public void Reset(bool force = false)
        {
            if (!resettable && !force)
            {
                return;
            }

            value = Clone(defaultValue);
        }

        public override Attribute[] GetCustomAttributes(bool inherit = true)
        {
            return Attribute.GetCustomAttributes(member, inherit);
        }
    }
}