using System.ClientModel;
using Azure.AI.OpenAI;
using Microsoft.Agents.AI;
using Microsoft.Extensions.AI;
using Microsoft.Extensions.Configuration;
using OpenAI;
using OpenAI.Chat;

namespace MAF1.Utils;

/// <summary>
/// 创建聊天 Agent 的工厂。根据 Endpoint 判断走 Azure OpenAI 还是 OpenAI 兼容接口（DeepSeek 等）。
/// 密钥优先级：appsettings Llm → 环境变量。浏览器永远拿不到 Key。
/// </summary>
public sealed class AgentFactory
{
    private readonly ChatClient _chatClient;
    private readonly bool _disableDeepSeekThinking;

    public AgentFactory(LlmOptions options)
    {
        if (string.IsNullOrWhiteSpace(options.ApiKey))
        {
            throw new InvalidOperationException(
                """
                还没有配置模型。请在 appsettings.json 的 Llm 节点，或环境变量中设置：
                  OPENAI_API_KEY / Llm:ApiKey
                  OPENAI_ENDPOINT / Llm:Endpoint
                  OPENAI_CHAT_MODEL / Llm:Model
                """);
        }

        string model = string.IsNullOrWhiteSpace(options.Model)
            ? DefaultModelFor(options.Endpoint)
            : options.Model;

        _disableDeepSeekThinking = LooksLikeDeepSeek(options.Endpoint);

        if (LooksLikeAzureOpenAI(options.Endpoint))
        {
            Console.Error.WriteLine($"使用 Azure OpenAI: {options.Endpoint}  部署: {model}");
            _chatClient = new AzureOpenAIClient(new Uri(options.Endpoint), new ApiKeyCredential(options.ApiKey))
                .GetChatClient(model);
            return;
        }

        OpenAIClientOptions clientOptions = new();
        if (!string.IsNullOrWhiteSpace(options.Endpoint))
        {
            clientOptions.Endpoint = ToOpenAICompatibleEndpoint(options.Endpoint);
        }

        Console.Error.WriteLine($"使用 OpenAI 兼容接口: {clientOptions.Endpoint?.ToString() ?? "https://api.openai.com/v1"}  模型: {model}");
        if (_disableDeepSeekThinking)
        {
            Console.Error.WriteLine("已关闭 DeepSeek thinking，避免 Handoff 多轮丢掉 reasoning_content 导致 HTTP 400。");
        }

        _chatClient = new OpenAIClient(new ApiKeyCredential(options.ApiKey), clientOptions)
            .GetChatClient(model);
    }

    /// <summary>把 ChatClient 包成 Microsoft.Agents.AI 的 AIAgent，并挂上 tools。Id 固定为 name，Handoff 工具才是 handoff_to_n1。</summary>
    public AIAgent CreateAgent(string name, string instructions, IList<AITool>? tools = null, string? description = null)
    {
        ChatOptions chatOptions = new()
        {
            Instructions = instructions,
            Tools = tools,
        };
        ChatClientAgentOptions options = new()
        {
            Id = name,
            Name = name,
            Description = description,
            ChatOptions = chatOptions,
        };
        return _chatClient.AsAIAgent(options, clientFactory: inner =>
            _disableDeepSeekThinking
                ? new ConfigureOptionsChatClient(inner, DeepSeekThinking.Disable)
                : inner);
    }

    /// <summary>合并配置文件和环境变量。插件进程里环境变量通常由宿主写入。</summary>
    public static LlmOptions Load(IConfiguration config)
    {
        LlmOptions options = config.GetSection("Llm").Get<LlmOptions>() ?? new LlmOptions();
        options.ApiKey = FirstNonEmpty(options.ApiKey, Env("OPENAI_API_KEY"), Env("AZURE_OPENAI_API_KEY"));
        options.Endpoint = FirstNonEmpty(options.Endpoint, Env("OPENAI_ENDPOINT"), Env("OPENAI_BASE_URL"), Env("AZURE_OPENAI_ENDPOINT"));
        options.Model = FirstNonEmpty(options.Model, Env("OPENAI_CHAT_MODEL"), Env("AZURE_OPENAI_DEPLOYMENT_NAME"));
        return options;
    }

    /// <summary>只读环境变量。进程外插件应优先用这个，不要去读宿主 appsettings.json。</summary>
    public static LlmOptions LoadFromEnvironment()
        => Load(new ConfigurationBuilder().AddEnvironmentVariables().Build());

    private static string DefaultModelFor(string? endpoint)
    {
        if (!string.IsNullOrWhiteSpace(endpoint) && endpoint.Contains("deepseek", StringComparison.OrdinalIgnoreCase))
        {
            return "deepseek-chat";
        }

        return "gpt-4o-mini";
    }

    private static bool LooksLikeDeepSeek(string? endpoint)
        => !string.IsNullOrWhiteSpace(endpoint)
            && endpoint.Contains("deepseek", StringComparison.OrdinalIgnoreCase);

    private static bool LooksLikeAzureOpenAI(string? endpoint)
    {
        if (string.IsNullOrWhiteSpace(endpoint) || !Uri.TryCreate(endpoint, UriKind.Absolute, out Uri? uri))
        {
            return false;
        }

        string host = uri.Host;
        return host.Contains("openai.azure.com", StringComparison.OrdinalIgnoreCase)
            || host.Contains("cognitiveservices.azure.com", StringComparison.OrdinalIgnoreCase)
            || host.Contains("services.ai.azure.com", StringComparison.OrdinalIgnoreCase);
    }

    /// <summary>OpenAI 兼容 API 要求 base URL 以 /v1 结尾，用户常只填到域名。</summary>
    private static Uri ToOpenAICompatibleEndpoint(string endpoint)
    {
        string trimmed = endpoint.TrimEnd('/');
        if (!trimmed.EndsWith("/v1", StringComparison.OrdinalIgnoreCase))
        {
            trimmed += "/v1";
        }

        return new Uri(trimmed);
    }

    private static string? Env(string name) => Environment.GetEnvironmentVariable(name);

    private static string FirstNonEmpty(params string?[] values)
    {
        foreach (string? value in values)
        {
            if (!string.IsNullOrWhiteSpace(value))
            {
                return value;
            }
        }

        return "";
    }
}