using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Text.Json;
using System.Threading.Tasks;

namespace AnotherReplayReader
{
    /// <summary>
    /// 服务端点配置（如 DeepSeek 官方、NVIDIA NIM）
    /// </summary>
    public class AiProvider
    {
        public string Name { get; set; } = string.Empty;
        public string BaseUrl { get; set; } = string.Empty;
        public string ApiKey { get; set; } = string.Empty;
        public List<AiModel> Models { get; set; } = [];

        public double DefaultTemperature { get; set; } = 0.35;
        public double DefaultTopP { get; set; } = 0.95;
        public int DefaultMaxTokens { get; set; } = 16384;
    }

    /// <summary>
    /// AI 分析提示词配置。
    /// </summary>
    public class AiPromptSettings
    {
        public bool UseCustomSystemPrompt { get; set; }
        public string CustomSystemPrompt { get; set; } = string.Empty;
        public string AdditionalRules { get; set; } = string.Empty;
    }

    /// <summary>
    /// 模型条目
    /// </summary>
    public class AiModel
    {
        public string ModelId { get; set; } = string.Empty;
        public string? DisplayName { get; set; }
        public bool IsStream { get; set; }
        public int ContextLength { get; set; } // 0 表示未知
        /// <summary>
        /// 一次请求的总 token 软上限（prompt + 输出/推理余量）。
        /// null 或 0 表示使用档位默认值：≥1M 上下文 → 160K；200K~256K → 100K；更小 → 0（不支持长录像）。
        /// </summary>
        public int? ContextBudget { get; set; }

        public Dictionary<string, object> ExtraParameters { get; set; } = [];

        /// <summary>
        /// 构建最终请求参数（合并 Provider 默认值、模型特有参数和运行时覆盖）
        /// </summary>
        public Dictionary<string, object> BuildRequestParams(
            AiProvider provider,
            double? temperatureOverride = null,
            double? topPOverride = null,
            int? maxTokensOverride = null)
        {
            var parameters = new Dictionary<string, object>
            {
                ["model"] = ModelId,
                ["temperature"] = temperatureOverride ?? provider.DefaultTemperature,
                ["top_p"] = topPOverride ?? provider.DefaultTopP,
                ["max_tokens"] = maxTokensOverride ?? provider.DefaultMaxTokens,
                ["stream"] = IsStream
            };

            foreach (var kv in this.ExtraParameters)
            {
                parameters[kv.Key] = kv.Value;
            }

            return parameters;
        }
    }

    /// <summary>
    /// 每次请求前的动态配置上下文（当前选中的 Provider 和 Model）
    /// </summary>
    public record AiRequestContext(AiProvider Provider, AiModel Model)
    {
        public Dictionary<string, object> BuildRequestParams(
            double? temperatureOverride = null,
            double? topPOverride = null,
            int? maxTokensOverride = null)
        {
            return Model.BuildRequestParams(Provider,
                temperatureOverride, topPOverride, maxTokensOverride);
        }
    }

    /// <summary>
    /// 内置已知模型信息（提供商无关，纯模型参数模板）
    /// </summary>
    public static class KnownModels
    {
        public const int SimilarityThreshold = 80;

        public static int GetSimilarity(string sourceModelId, string targetModelId)
        {
            // prefer exact match
            if (sourceModelId.Equals(targetModelId, StringComparison.OrdinalIgnoreCase))
            {
                return 100;
            }
            // match the part after slash, e.g. "deepseek-ai/deepseek-v4-flash" vs "deepseek-v4-flash"
            // if last part matches, return 90
            var sourceModelIdLastPart = sourceModelId.Split('/').LastOrDefault() ?? sourceModelId;
            var targetModelIdLastPart = targetModelId.Split('/').LastOrDefault() ?? targetModelId;
            if (sourceModelIdLastPart.Equals(targetModelIdLastPart, StringComparison.OrdinalIgnoreCase))
            {
                return 90;
            }
            return 0;
        }

        /// <summary>
        /// 返回一组已知模型，包含正确的 ExtraParameters。
        /// 调用方可按需复制到 Provider 的 Models 列表中。
        /// </summary>
        public static List<AiModel> GetAll()
        {
            return
            [
                // DeepSeek 官方
                new()
                {
                    ModelId = "deepseek-v4-flash",
                    DisplayName = "DeepSeek V4 Flash",
                    IsStream = true,
                    ContextLength = 1_000_000,
                    ExtraParameters = new()
                    {
                        ["thinking"] = new { type = "enabled" },
                        ["reasoning_effort"] = "high"
                    }
                },
                new()
                {
                    ModelId = "deepseek-v4-pro",
                    DisplayName = "DeepSeek V4 Pro",
                    IsStream = true,
                    ContextLength = 1_000_000,
                    ExtraParameters = new()
                    {
                        ["thinking"] = new { type = "enabled" },
                        ["reasoning_effort"] = "high"
                    }
                },
                // NVIDIA NIM 上的 DeepSeek 模型
                new()
                {
                    ModelId = "deepseek-ai/deepseek-v4-flash",
                    DisplayName = "DeepSeek V4 Flash (NIM)",
                    IsStream = true,
                    ContextLength = 1_000_000,
                    ExtraParameters = new()
                    {
                        // ["chat_template_kwargs"] = new { thinking = true },
                        ["thinking"] = new { type = "enabled" },
                        ["reasoning_effort"] = "high",
                    }
                },
                new()
                {
                    ModelId = "deepseek-ai/deepseek-v4-pro",
                    DisplayName = "DeepSeek V4 Pro (NIM)",
                    IsStream = true,
                    ContextLength = 1_000_000,
                    ExtraParameters = new()
                    {
                        // ["chat_template_kwargs"] = new { thinking = true },
                        ["thinking"] = new { type = "enabled" },
                        ["reasoning_effort"] = "high",
                    }
                },
                // NVIDIA Nemotron
                new()
                {
                    ModelId = "nvidia/nemotron-3-super-120b-a12b",
                    DisplayName = "Nemotron Super 120B (NIM)",
                    IsStream = true,
                    ContextLength = 1_000_000,
                    ExtraParameters = new()
                    {
                        ["reasoning_budget"] = 16384
                    }
                },
                // Minimax
                new()
                {
                    ModelId = "minimaxai/minimax-m3",
                    DisplayName = "MiniMax-M3 (NIM)",
                    IsStream = false,
                    ContextLength = 1_000_000,
                    ExtraParameters = []
                },
                // Kimi
                new()
                {
                    ModelId = "moonshotai/kimi-k2.6",
                    DisplayName = "Kimi-K2.6 (NIM)",
                    IsStream = false,
                    ContextLength = 256_000,
                    ExtraParameters = []
                },
                // Google DiffusionGemma
                new()
                                {
                    ModelId = "google/diffusiongemma-26b-a4b-it",
                    DisplayName = "DiffusionGemma 26B A4B IT (NIM)",
                    IsStream = false,
                    ContextLength = 250_000,
                    ExtraParameters = new()
                    {
                        ["chat_template_kwargs"] = new { enable_thinking = true },
                    }
                },
                // OpenAI 兼容
                new()
                {
                    ModelId = "openai/gpt-oss-120b",
                    DisplayName = "GPT OSS 120B (NIM)",
                    IsStream = true,
                    ContextLength = 128_000,
                    ExtraParameters = new()
                    {
                        ["reasoning_effort"] = "medium"
                    }
                }
            ];
        }
    }

    /// <summary>
    /// 从 OpenAI 兼容的 /v1/models 端点获取可用模型 ID 列表
    /// </summary>
    public static class AiModelFetcher
    {
        public static async Task<List<string>> FetchModelsAsync(
            string baseUrl, string apiKey)
        {
            baseUrl = baseUrl.TrimEnd('/') + "/";

            var models = new List<string>();

            using var client = new HttpClient();
            var request = new HttpRequestMessage(
                HttpMethod.Get, new Uri(new(baseUrl), "models"));
            request.Headers.Add("Authorization", $"Bearer {apiKey}");

            var response = await client.SendAsync(request);
            if (!response.IsSuccessStatusCode)
            {
                throw new Exception(
                    $"获取模型列表失败: HTTP {(int)response.StatusCode}");
            }

            var json = await response.Content.ReadAsStringAsync();
            using var doc = JsonDocument.Parse(json);
            if (doc.RootElement.TryGetProperty("data", out var dataArray))
            {
                foreach (var item in dataArray.EnumerateArray())
                {
                    if (item.TryGetProperty("id", out var idProp))
                    {
                        var id = idProp.GetString();
                        if (!string.IsNullOrEmpty(id))
                        {
                            models.Add(id!);
                        }
                    }
                }
            }
            return models;
        }
    }

    /// <summary>
    /// 全局 AI 配置（多个 Provider）的持久化管理
    /// </summary>
    public class AiSettings
    {
        public List<AiProvider> Providers { get; set; } = [];
        public AiPromptSettings Prompt { get; set; } = new();

        /// <summary>
        /// 上次选中的 Provider 名称（持久化；用于下次打开设置页时恢复）。
        /// 按名称识别，Provider 被重命名/删除后自动回退到第一个 Provider。
        /// </summary>
        public string? CurrentProviderName { get; set; }

        /// <summary>
        /// 上次选中的模型 ID（持久化；与 <see cref="CurrentProviderName"/> 配合使用）。
        /// 模型被删除后自动回退到该 Provider 的第一个模型。
        /// </summary>
        public string? CurrentModelId { get; set; }

        /// <summary>
        /// 更新并持久化当前选中的 Provider 与模型。
        /// </summary>
        public void SetCurrentSelection(AiProvider provider, AiModel model)
        {
            CurrentProviderName = provider.Name;
            CurrentModelId = model.ModelId;
        }

        /// <summary>
        /// 解析持久化的上次选择。任一标识缺失或对应 Provider/Model 已不存在时返回 null。
        /// </summary>
        public (AiProvider Provider, AiModel Model)? ResolveLastSelection()
        {
            var providerName = CurrentProviderName?.Trim();
            var modelId = CurrentModelId?.Trim();
            if (string.IsNullOrEmpty(providerName) || string.IsNullOrEmpty(modelId))
            {
                return null;
            }

            var provider = Providers.FirstOrDefault(p =>
                string.Equals(p.Name, providerName, StringComparison.OrdinalIgnoreCase));
            if (provider is null)
            {
                return null;
            }

            var model = provider.Models.FirstOrDefault(m =>
                string.Equals(m.ModelId, modelId, StringComparison.OrdinalIgnoreCase));
            if (model is null)
            {
                return null;
            }

            return (provider, model);
        }

        private static readonly string ConfigPath = Path.Combine(
            AppContext.BaseDirectory,
            "AnotherReplayReader.ai_settings.json");

        public static AiSettings Load()
        {
            try
            {
                if (File.Exists(ConfigPath))
                {
                    var json = File.ReadAllText(ConfigPath);
                    var settings = JsonSerializer.Deserialize<AiSettings>(json);
                    if (settings is { } value && value.Providers.Count > 0)
                    {
                        value.Prompt ??= new AiPromptSettings();
                        return settings;
                    }
                }
            }
            catch (Exception ex)
            {
                // 返回默认配置
                Debug.Instance.DebugMessage += $"加载 AI 配置失败: {ex}\r\n";
            }

            // 返回默认配置：包含两个常用 Provider，各附一个内置模型
            var defaults = new AiSettings();
            var nimProvider = new AiProvider
            {
                Name = "NVIDIA NIM",
                BaseUrl = "https://integrate.api.nvidia.com/v1",
                ApiKey = "",
                Models =
                [
                    KnownModels.GetAll().First(m => m.ModelId == "deepseek-ai/deepseek-v4-flash")
                ]
            };
            var deepseekProvider = new AiProvider
            {
                Name = "DeepSeek 官方",
                BaseUrl = "https://api.deepseek.com",
                ApiKey = "",
                Models =
                [
                    KnownModels.GetAll().First(m => m.ModelId == "deepseek-v4-flash")
                ]
            };
            defaults.Providers.Add(nimProvider);
            defaults.Providers.Add(deepseekProvider);

            return defaults;
        }

        public void Save()
        {
            var dir = Path.GetDirectoryName(ConfigPath);
            if (dir is not null)
            {
                Directory.CreateDirectory(dir);
            }

            var json = JsonSerializer.Serialize(this, new JsonSerializerOptions
            {
                WriteIndented = true
            });
            File.WriteAllText(ConfigPath, json);
        }
    }
}