namespace MiaoJiZhang.Api.Services;

public interface ILlmClient
{
    bool IsEnabled { get; }
    Task<IntentResult?> TryParseIntentAsync(string userText, CancellationToken ct = default);
    Task<string?> TryGenerateReplyAsync(string systemPrompt, string userText, CancellationToken ct = default);
    Task<IReadOnlyList<ImageParseResult>?> AnalyzeImageAsync(
        byte[] imageBytes,
        string mimeType,
        CancellationToken ct = default);
    Task<(bool Ok, string? Error)> TestConnectionAsync(CancellationToken ct = default);

    Task<AgentRunResponse> RunAgentAsync(
        string systemPrompt,
        string userText,
        IReadOnlyList<AgentToolDefinition> tools,
        Func<AgentToolCall, CancellationToken, Task<string>> executeTool,
        Func<string, CancellationToken, Task>? onToken = null,
        Func<string, CancellationToken, Task>? onToolRunning = null,
        CancellationToken ct = default);

    /// <summary>流式生成回复。将 LLM 返回的 token 逐个写入 writer，完成时返回。</summary>
    Task StreamReplyAsync(
        string systemPrompt,
        string userText,
        Func<string, CancellationToken, Task> onToken,
        CancellationToken ct = default);
}

public record AgentToolDefinition(
    string Name,
    string Description,
    object Parameters);

public record AgentToolCall(
    string CallId,
    string Name,
    string Arguments);

public record AgentRunResponse(
    string Text,
    int ToolCallCount);

public record ImageParseResult(
    string Type,
    decimal Amount,
    string CategoryName,
    string? PaymentMethod,
    string Note,
    DateTime? OccurredAt);

public class NullLlmClient : ILlmClient
{
    public bool IsEnabled => false;

    public Task<IntentResult?> TryParseIntentAsync(
        string userText,
        CancellationToken ct = default) =>
        Task.FromResult<IntentResult?>(null);

    public Task<string?> TryGenerateReplyAsync(
        string systemPrompt,
        string userText,
        CancellationToken ct = default) =>
        Task.FromResult<string?>(null);

    public Task<IReadOnlyList<ImageParseResult>?> AnalyzeImageAsync(
        byte[] imageBytes,
        string mimeType,
        CancellationToken ct = default) =>
        Task.FromResult<IReadOnlyList<ImageParseResult>?>(null);

    public Task<(bool Ok, string? Error)> TestConnectionAsync(
        CancellationToken ct = default) =>
        Task.FromResult<(bool, string?)>((false, "API Key 为空"));

    public Task<AgentRunResponse> RunAgentAsync(
        string systemPrompt,
        string userText,
        IReadOnlyList<AgentToolDefinition> tools,
        Func<AgentToolCall, CancellationToken, Task<string>> executeTool,
        Func<string, CancellationToken, Task>? onToken = null,
        Func<string, CancellationToken, Task>? onToolRunning = null,
        CancellationToken ct = default) =>
        Task.FromResult(new AgentRunResponse("", 0));

    public async Task StreamReplyAsync(
        string systemPrompt,
        string userText,
        Func<string, CancellationToken, Task> onToken,
        CancellationToken ct = default)
    {
        await Task.CompletedTask;
    }
}