/*************************************************************************
 * ModernUO                                                              *
 * Copyright 2019-2021 - ModernUO Development Team                       *
 * Email: hi@modernuo.com                                                *
 * File: DictionaryMigrationRule.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 DictionaryMigrationRule : ISerializableMigrationRule
    {
        public string RuleName => nameof(DictionaryMigrationRule);

        public bool GenerateRuleState(
            Compilation compilation,
            ISymbol symbol,
            ImmutableArray<AttributeData> attributes,
            ImmutableArray<INamedTypeSymbol> serializableTypes,
            ImmutableArray<INamedTypeSymbol> embeddedSerializableTypes,
            ISymbol? parentSymbol,
            out string[] ruleArguments
        )
        {
            if (symbol is not INamedTypeSymbol namedTypeSymbol || !symbol.IsDictionary(compilation))
            {
                ruleArguments = null;
                return false;
            }

            var keySymbolType = namedTypeSymbol.TypeArguments[0];

            var serializableKeyProperty = SerializableMigrationRulesEngine.GenerateSerializableProperty(
                compilation,
                "KeyEntry",
                keySymbolType,
                0,
                attributes,
                serializableTypes,
                embeddedSerializableTypes,
                parentSymbol,
                null
            );

            var valueSymbolType = namedTypeSymbol.TypeArguments[1];

            var serializableValueProperty = SerializableMigrationRulesEngine.GenerateSerializableProperty(
                compilation,
                "ValueEntry",
                valueSymbolType,
                0,
                attributes,
                serializableTypes,
                embeddedSerializableTypes,
                parentSymbol,
                null
            );

            var extraOptions = "";
            if (attributes.Any(a => a.IsTidy(compilation)))
            {
                extraOptions += "@Tidy";
            }

            var keyArgumentsLength = serializableKeyProperty.RuleArguments?.Length ?? 0;
            var valueArgumentsLength = serializableValueProperty.RuleArguments?.Length ?? 0;
            var index = 0;

            ruleArguments = new string[7 + keyArgumentsLength + valueArgumentsLength];
            ruleArguments[index++] = extraOptions;
            ruleArguments[index++] = keySymbolType.ToDisplayString();
            ruleArguments[index++] = serializableKeyProperty.Rule;
            ruleArguments[index++] = keyArgumentsLength.ToString();

            if (keyArgumentsLength > 0)
            {
                Array.Copy(serializableKeyProperty.RuleArguments!, 0, ruleArguments, index, keyArgumentsLength);
                index += keyArgumentsLength;
            }

            ruleArguments[index++] = valueSymbolType.ToDisplayString();
            ruleArguments[index++] = serializableValueProperty.Rule;
            ruleArguments[index++] = valueArgumentsLength.ToString();

            if (valueArgumentsLength > 0)
            {
                Array.Copy(serializableValueProperty.RuleArguments!, 0, ruleArguments, index, valueArgumentsLength);
            }

            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 ruleArguments = property.RuleArguments;
            var index = 1;
            var keyType = ruleArguments![index++];

            var keyElementRule = SerializableMigrationRulesEngine.Rules[ruleArguments[index++]];
            var keyRuleArguments = new string[int.Parse(ruleArguments[index++])];

            if (keyRuleArguments.Length > 0)
            {
                Array.Copy(ruleArguments, index, keyRuleArguments, 0, keyRuleArguments.Length);
                index += keyRuleArguments.Length;
            }

            var valueType = ruleArguments[index++];
            var valueElementRule = SerializableMigrationRulesEngine.Rules[ruleArguments[index++]];
            var valueRuleArguments = new string[int.Parse(ruleArguments[index++])];

            if (valueRuleArguments.Length > 0)
            {
                Array.Copy(ruleArguments, index, valueRuleArguments, 0, valueRuleArguments.Length);
            }

            var propertyName = property.Name;
            var propertyVarPrefix = $"{char.ToLower(propertyName[0])}{propertyName.Substring(1, propertyName.Length - 1)}";
            var propertyIndex = $"{propertyVarPrefix}Index";
            var propertyKeyEntry = $"{propertyVarPrefix}Key";
            var propertyValueEntry = $"{propertyVarPrefix}Value";
            var propertyCount = $"{propertyVarPrefix}Count";

            source.AppendLine($"{indent}{ruleArguments[1]} {propertyKeyEntry};");
            source.AppendLine($"{indent}{valueType} {propertyValueEntry};");
            source.AppendLine($"{indent}var {propertyCount} = reader.ReadEncodedInt();");
            source.AppendLine($"{indent}{propertyName} = new System.Collections.Generic.Dictionary<{keyType}, {valueType}>({propertyCount});");
            source.AppendLine($"{indent}for (var {propertyIndex} = 0; {propertyIndex} < {propertyCount}; {propertyIndex}++)");
            source.AppendLine($"{indent}{{");

            var serializableKeyElement = new SerializableProperty
            {
                Name = propertyKeyEntry,
                Type = keyType,
                Rule = keyElementRule.RuleName,
                RuleArguments = keyRuleArguments
            };

            keyElementRule.GenerateDeserializationMethod(source, $"{indent}    ", serializableKeyElement, parentReference);

            var serializableValueElement = new SerializableProperty
            {
                Name = propertyValueEntry,
                Type = valueType,
                Rule = valueElementRule.RuleName,
                RuleArguments = valueRuleArguments
            };

            valueElementRule.GenerateDeserializationMethod(source, $"{indent}    ", serializableValueElement, parentReference);
            source.AppendLine($"{indent}    {propertyName}.Add({propertyKeyEntry}, {propertyValueEntry});");

            source.AppendLine($"{indent}}}");
        }

        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 ruleArguments = property.RuleArguments;
            var index = 0;
            var shouldTidy = ruleArguments![index++].Contains("@Tidy");
            var keyType = ruleArguments![index++];

            var keyElementRule = SerializableMigrationRulesEngine.Rules[ruleArguments![index++]];
            var keyRuleArguments = new string[int.Parse(ruleArguments[index++])];

            if (keyRuleArguments.Length > 0)
            {
                Array.Copy(ruleArguments, index, keyRuleArguments, 0, keyRuleArguments.Length);
                index += keyRuleArguments.Length;
            }

            var valueType = ruleArguments[index++];
            var valueElementRule = SerializableMigrationRulesEngine.Rules[ruleArguments[index++]];
            var valueRuleArguments = new string[int.Parse(ruleArguments[index++])];

            if (valueRuleArguments.Length > 0)
            {
                Array.Copy(ruleArguments, index, valueRuleArguments, 0, valueRuleArguments.Length);
            }

            var propertyName = property.Name;
            var propertyVarPrefix = $"{char.ToLower(propertyName[0])}{propertyName.Substring(1, propertyName.Length - 1)}";
            var propertyKeyEntry = $"{propertyVarPrefix}Key";
            var propertyValueEntry = $"{propertyVarPrefix}Value";
            var propertyCount = $"{propertyVarPrefix}Count";

            if (shouldTidy)
            {
                source.AppendLine($"{indent}{property.Name}?.Tidy();");
            }
            source.AppendLine($"{indent}var {propertyCount} = {property.Name}?.Count ?? 0;");
            source.AppendLine($"{indent}writer.WriteEncodedInt({propertyCount});");
            source.AppendLine($"{indent}if ({propertyCount} > 0)");
            source.AppendLine($"{indent}{{");
            source.AppendLine($"{indent}    foreach (var ({propertyKeyEntry}, {propertyValueEntry}) in {property.Name}!)");
            source.AppendLine($"{indent}    {{");

            var serializableKeyElement = new SerializableProperty
            {
                Name = propertyKeyEntry,
                Type = keyType,
                Rule = keyElementRule.RuleName,
                RuleArguments = keyRuleArguments
            };

            keyElementRule.GenerateSerializationMethod(source, $"{indent}        ", serializableKeyElement);

            var serializableValueElement = new SerializableProperty
            {
                Name = propertyValueEntry,
                Type = valueType,
                Rule = valueElementRule.RuleName,
                RuleArguments = valueRuleArguments
            };

            valueElementRule.GenerateSerializationMethod(source, $"{indent}        ", serializableValueElement);

            source.AppendLine($"{indent}    }}");
            source.AppendLine($"{indent}}}");
        }
    }
}