using System;
using System.Linq;
using System.Text;
using GFramework.SourceGenerators.Abstractions.logging;
using GFramework.SourceGenerators.Common.constants;
using GFramework.SourceGenerators.Common.generator;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace GFramework.SourceGenerators.logging;

/// <summary>
///     日志生成器，用于为标记了LogAttribute的类自动生成日志字段
/// </summary>
[Generator]
public sealed class LoggerGenerator : AttributeClassGeneratorBase
{
    /// <summary>
    /// 强类型 Attribute
    /// </summary>
    protected override Type AttributeType => typeof(LogAttribute);

    /// <summary>
    /// 用于语法快速筛选
    /// </summary>
    protected override string AttributeShortNameWithoutSuffix => "Log";

    /// <summary>
    /// 对类进行额外语义校验（可选）
    /// </summary>
    protected override bool ValidateSymbol(
        SourceProductionContext context,
        ClassDeclarationSyntax syntax,
        INamedTypeSymbol symbol,
        AttributeData attr)
    {
        // 可以加自定义规则，比如确保类是 public 或实现某接口
        return true;
    }

    /// <summary>
    /// 生成 Logger 字段的代码
    /// </summary>
    protected override string Generate(INamedTypeSymbol symbol, AttributeData attr)
    {
        var ns = symbol.ContainingNamespace.IsGlobalNamespace
            ? null
            : symbol.ContainingNamespace.ToDisplayString();

        var className = symbol.Name;

        // 解析构造函数参数
        var name = className;
        if (attr.ConstructorArguments.Length > 0)
        {
            var argValue = attr.ConstructorArguments[0].Value;
            name = argValue is string s && !string.IsNullOrWhiteSpace(s)
                ? s
                : className;
        }

        // 解析命名参数
        var fieldName = GetNamedArg(attr, "FieldName")?.ToString() ?? "_log";
        var access = GetNamedArg(attr, "AccessModifier")?.ToString() ?? "private";
        var isStaticObj = GetNamedArg(attr, "IsStatic");
        var isStatic = isStaticObj is not bool b || b; // 默认 true
        var staticKeyword = isStatic ? "static " : "";

        var sb = new StringBuilder();
        sb.AppendLine("// <auto-generated />");
        sb.AppendLine($"using {PathContests.CoreAbstractionsNamespace}.logging;");
        sb.AppendLine($"using {PathContests.CoreNamespace}.logging;");

        if (ns is not null)
        {
            sb.AppendLine($"namespace {ns};");
            sb.AppendLine();
        }

        sb.AppendLine($"partial class {className}");
        sb.AppendLine("{");
        sb.AppendLine("    /// <summary>Auto-generated logger</summary>");
        sb.AppendLine(
            $"    {access} {staticKeyword}readonly ILogger {fieldName} = new ConsoleLoggerFactory().GetLogger(\"{name}\");");
        sb.AppendLine("}");

        return sb.ToString().TrimEnd();
    }

    /// <summary>
    /// 可以自定义生成文件名
    /// </summary>
    protected override string GetHintName(INamedTypeSymbol symbol)
        => $"{symbol.Name}.Logger.g.cs";

    private static object? GetNamedArg(AttributeData attr, string name)
        => attr.NamedArguments.FirstOrDefault(kv => kv.Key == name).Value.Value;
}