DeutschLernen/GermanApp/Application/Models/MistralResponse.cs

using System.Text.Json.Serialization;
using GermanApp.Domain.Interfaces;

namespace GermanApp.Application.Models;

/// <summary>
/// Response model for Mistral completion and chat completion APIs.
/// </summary>
/// <remarks>
/// See: https://docs.mistral.ai/api/#operation/createCompletion
/// See: https://docs.mistral.ai/api/#operation/createChatCompletion
/// </remarks>
public record MistralResponse
{
    /// <summary>
    /// Unique identifier for the completion.
    /// </summary>
    [JsonPropertyName("id")]
    public string Id { get; init; } = string.Empty;

    /// <summary>
    /// The object type (always "text_completion" or "chat.completion").
    /// </summary>
    [JsonPropertyName("object")]
    public string Object { get; init; } = string.Empty;

    /// <summary>
    /// The Unix timestamp (in seconds) of when the completion was created.
    /// </summary>
    [JsonPropertyName("created")]
    public long Created { get; init; }

    /// <summary>
    /// The model used for the completion.
    /// </summary>
    [JsonPropertyName("model")]
    public string Model { get; init; } = string.Empty;

    /// <summary>
    /// The list of completion choices generated by the model.
    /// </summary>
    [JsonPropertyName("choices")]
    public IReadOnlyList<MistralChoice> Choices { get; init; } = new List<MistralChoice>();

    /// <summary>
    /// Usage statistics for the completion.
    /// </summary>
    [JsonPropertyName("usage")]
    public MistralUsage Usage { get; init; } = new();

    /// <summary>
    /// Gets the first choice's text content.
    /// Convenience property for single-completion requests.
    /// </summary>
    [JsonIgnore]
    public string FirstChoiceText => Choices.Count > 0 ? Choices[0].Text : string.Empty;

    /// <summary>
    /// Gets the first choice's message content (for chat completions).
    /// </summary>
    [JsonIgnore]
    public string FirstChoiceMessageContent => 
        Choices.Count > 0 && Choices[0].Message != null 
            ? Choices[0].Message.Content 
            : string.Empty;

    /// <summary>
    /// Gets all generated texts from all choices.
    /// </summary>
    [JsonIgnore]
    public IReadOnlyList<string> AllChoiceTexts => Choices.Select(c => c.Text).ToList();

    /// <summary>
    /// Checks if the response contains any valid completions.
    /// </summary>
    [JsonIgnore]
    public bool HasValidChoices => Choices != null && Choices.Count > 0 && 
        Choices.Any(c => !string.IsNullOrWhiteSpace(c.Text) || c.Message != null);
}

/// <summary>
/// A single completion choice returned by Mistral API.
/// </summary>
public record MistralChoice
{
    /// <summary>
    /// The generated text for this choice.
    /// </summary>
    [JsonPropertyName("text")]
    public string Text { get; init; } = string.Empty;

    /// <summary>
    /// For chat completions, this contains the message object.
    /// </summary>
    [JsonPropertyName("message")]
    public MistralChatMessage? Message { get; init; }

    /// <summary>
    /// The reason the model stopped generating tokens (e.g., "stop", "length", "error").
    /// </summary>
    [JsonPropertyName("finish_reason")]
    public string FinishReason { get; init; } = string.Empty;

    /// <summary>
    /// The index of this choice in the list of choices.
    /// </summary>
    [JsonPropertyName("index")]
    public int Index { get; init; }

    /// <summary>
    /// Log probability information for the generated tokens.
    /// </summary>
    [JsonPropertyName("logprobs")]
    public object? LogProbs { get; init; }
}

/// <summary>
/// Message object returned in chat completion choices.
/// </summary>
public record MistralChatMessage
{
    /// <summary>
    /// The role of the message author.
    /// </summary>
    [JsonPropertyName("role")]
    public string Role { get; init; } = string.Empty;

    /// <summary>
    /// The content of the message.
    /// </summary>
    [JsonPropertyName("content")]
    public string Content { get; init; } = string.Empty;
}

/// <summary>
/// Token usage statistics from Mistral API.
/// </summary>
public record MistralUsage
{
    /// <summary>
    /// Number of tokens in the prompt.
    /// </summary>
    [JsonPropertyName("prompt_tokens")]
    public int PromptTokens { get; init; }

    /// <summary>
    /// Number of tokens generated in the completion.
    /// </summary>
    [JsonPropertyName("completion_tokens")]
    public int CompletionTokens { get; init; }

    /// <summary>
    /// Total number of tokens used (prompt + completion).
    /// </summary>
    [JsonPropertyName("total_tokens")]
    public int TotalTokens { get; init; }

    /// <summary>
    /// Gets the total cost estimate based on token usage.
    /// Note: Actual pricing may vary based on Mistral's pricing model.
    /// </summary>
    [JsonIgnore]
    public decimal EstimatedCost => TotalTokens * 0.0000025m; // Approx $0.0000025 per token for mistral-medium
}

/// <summary>
/// Error response from Mistral API.
/// </summary>
public record MistralErrorResponse
{
    /// <summary>
    /// The object type (always "error").
    /// </summary>
    [JsonPropertyName("object")]
    public string Object { get; init; } = string.Empty;

    /// <summary>
    /// The error message.
    /// </summary>
    [JsonPropertyName("message")]
    public string Message { get; init; } = string.Empty;

    /// <summary>
    /// The type of error that occurred.
    /// </summary>
    [JsonPropertyName("type")]
    public string Type { get; init; } = string.Empty;

    /// <summary>
    /// The HTTP status code associated with the error.
    /// </summary>
    [JsonIgnore]
    public int? StatusCode { get; init; }

    /// <summary>
    /// Additional error details.
    /// </summary>
    [JsonPropertyName("details")]
    public object? Details { get; init; }

    /// <summary>
    /// Maps the error type to an AiErrorCode.
    /// </summary>
    [JsonIgnore]
    public AiErrorCode ErrorCode => Type switch
    {
        "rate_limit_exceeded" or "rate_limit" => AiErrorCode.RateLimited,
        "invalid_request_error" => AiErrorCode.InvalidRequest,
        "authentication_error" or "invalid_api_key" => AiErrorCode.AuthenticationError,
        "server_error" or "internal_server_error" => AiErrorCode.Temporary,
        "timeout" => AiErrorCode.Timeout,
        _ => AiErrorCode.Unknown
    };
}

/// <summary>
/// Response wrapper for listing Mistral models.
/// </summary>
public record MistralListModelsResponse
{
    /// <summary>
    /// The object type (always "list").
    /// </summary>
    [JsonPropertyName("object")]
    public string Object { get; init; } = string.Empty;

    /// <summary>
    /// List of available models.
    /// </summary>
    [JsonPropertyName("data")]
    public IReadOnlyList<MistralModel> Data { get; init; } = new List<MistralModel>();
}