/*************************************************************************
 * ModernUO                                                              *
 * Copyright 2019-2021 - ModernUO Development Team                       *
 * Email: hi@modernuo.com                                                *
 * File: TimerMigrationRule.cs                                           *
 *                                                                       *
 * This program is free software: you can redistribute it and/or modify  *
 * it under the terms of the GNU General Public License as published by  *
 * the Free Software Foundation, either version 3 of the License, or     *
 * (at your option) any later version.                                   *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *************************************************************************/

using System;
using System.Collections.Immutable;
using System.Linq;
using System.Text;
using Microsoft.CodeAnalysis;
using SerializationGenerator;

namespace SerializableMigration
{
    public class TimerMigrationRule : ISerializableMigrationRule, IPostDeserializeMethod
    {
        public string RuleName => nameof(TimerMigrationRule);

        public bool GenerateRuleState(
            Compilation compilation,
            ISymbol symbol,
            ImmutableArray<AttributeData> attributes,
            ImmutableArray<INamedTypeSymbol> serializableTypes,
            ImmutableArray<INamedTypeSymbol> embeddedSerializableTypes,
            ISymbol? parentSymbol,
            out string[] ruleArguments
        )
        {
            if (!(symbol is ITypeSymbol typeSymbol && typeSymbol.IsTimer(compilation)))
            {
                ruleArguments = null;
                return false;
            }

            ruleArguments = attributes.Any(a => a.IsTimerDrift(compilation))
                ? new[] { "@TimerDrift" }
                : new[] { "" };

            return true;
        }

        public void GenerateDeserializationMethod(StringBuilder source, string indent, SerializableProperty property, string? parentReference)
        {
            var expectedRule = RuleName;
            var ruleName = property.Rule;
            if (expectedRule != ruleName)
            {
                throw new ArgumentException($"Invalid rule applied to property {ruleName}. Expecting {expectedRule}, but received {ruleName}.");
            }

            var propertyName = property.Name;
            var ruleArguments = property.RuleArguments;
            var driftTimer = ruleArguments![0].Contains("@TimerDrift");

            var readTimer = driftTimer ? "reader.ReadDeltaTime()" : "reader.ReadDateTime()";
            source.AppendLine($"{indent}var {propertyName}Next = {readTimer};");
            source.AppendLine($"{indent}var {propertyName}Delay = {propertyName}Next == System.DateTime.MinValue ? System.TimeSpan.MinValue : {propertyName}Next - Core.Now;");
        }

        public void GenerateSerializationMethod(StringBuilder source, string indent, SerializableProperty property)
        {
            var expectedRule = RuleName;
            var ruleName = property.Rule;
            if (expectedRule != ruleName)
            {
                throw new ArgumentException($"Invalid rule applied to property {ruleName}. Expecting {expectedRule}, but received {ruleName}.");
            }

            var propertyName = property.Name;
            var ruleArguments = property.RuleArguments;
            var driftTimer = ruleArguments![0].Contains("@TimerDrift");

            var writerMethod = driftTimer ? "WriteDeltaTime" : "Write";
            source.AppendLine($"{indent}writer.{writerMethod}({propertyName}?.Next ?? System.DateTime.MinValue);");
        }

        public void PostDeserializeMethod(
            StringBuilder source, string indent, SerializableProperty property, Compilation compilation, INamedTypeSymbol classSymbol
        )
        {
            var deserializeTimerMethod = classSymbol
                .GetMembers()
                .OfType<IMethodSymbol>()
                .FirstOrDefault(
                    m =>
                    {
                        if (!m.ReturnsVoid || m.Parameters.Length != 1 || !m.Parameters[0].Type.IsTimeSpan(compilation))
                        {
                            return false;
                        }

                        return m.GetAttributes()
                            .FirstOrDefault(
                                attr =>
                                {
                                    if (!SymbolEqualityComparer.Default.Equals(
                                        attr.AttributeClass,
                                        compilation.GetTypeByMetadataName(
                                            SymbolMetadata.DESERIALIZE_TIMER_FIELD_ATTRIBUTE
                                        )
                                    ))
                                    {
                                        return false;
                                    }

                                    var order = (int)attr.ConstructorArguments[0].Value!;
                                    return order == property.Order;
                                }
                            ) != null;
                    }
                ) ?? throw new Exception("Serializing a timer requires a method with the DeserializeTimerField attribute to handle creating the timer itself.");

            source.AppendLine($"{indent}{deserializeTimerMethod.Name}({property.Name}Delay);");
        }
    }
}