namespace Service;

public interface IBudgetService
{
    Task<List<BudgetResult>> GetListAsync(DateTime? referenceDate = null);

    Task<BudgetResult?> GetStatisticsAsync(long id, DateTime? referenceDate = null);

    Task<string> ArchiveBudgetsAsync(int year, int month);

    /// <summary>
    /// 获取指定分类的统计信息（月度和年度）
    /// </summary>
    Task<BudgetCategoryStats> GetCategoryStatsAsync(BudgetCategory category, DateTime? referenceDate = null);
}

public class BudgetService(
    IBudgetRepository budgetRepository,
    IBudgetArchiveRepository budgetArchiveRepository,
    ITransactionRecordRepository transactionRecordRepository,
    IOpenAiService openAiService,
    IConfigService configService,
    IMessageRecordService messageService,
    ILogger<BudgetService> logger
) : IBudgetService
{
    public async Task<List<BudgetResult>> GetListAsync(DateTime? referenceDate = null)
    {
        var budgets = await budgetRepository.GetAllAsync();
        var dtos = new List<BudgetResult?>();

        foreach (var budget in budgets)
        {
            var currentAmount = await CalculateCurrentAmountAsync(budget, referenceDate);
            dtos.Add(BudgetResult.FromEntity(budget, currentAmount, referenceDate));
        }

        // 创造虚拟的存款预算
        dtos.Add(await GetVirtualSavingsDtoAsync(
            BudgetPeriodType.Month,
            referenceDate,
            budgets));
        dtos.Add(await GetVirtualSavingsDtoAsync(
            BudgetPeriodType.Year,
            referenceDate,
            budgets));

        return dtos.Where(dto => dto != null).Cast<BudgetResult>().ToList();
    }

    public async Task<BudgetResult?> GetStatisticsAsync(long id, DateTime? referenceDate = null)
    {
        if (id == -1)
        {
            return await GetVirtualSavingsDtoAsync(BudgetPeriodType.Year, referenceDate);
        }
        if (id == -2)
        {
            return await GetVirtualSavingsDtoAsync(BudgetPeriodType.Month, referenceDate);
        }

        var budget = await budgetRepository.GetByIdAsync(id);
        if (budget == null)
        {
            return null;
        }

        var currentAmount = await CalculateCurrentAmountAsync(budget, referenceDate);
        return BudgetResult.FromEntity(budget, currentAmount, referenceDate);
    }

    public async Task<BudgetCategoryStats> GetCategoryStatsAsync(BudgetCategory category, DateTime? referenceDate = null)
    {
        var budgets = (await budgetRepository.GetAllAsync()).ToList();
        var refDate = referenceDate ?? DateTime.Now;

        var result = new BudgetCategoryStats();

        // 获取月度统计
        result.Month = await CalculateCategoryStatsAsync(budgets, category, BudgetPeriodType.Month, refDate);

        // 获取年度统计
        result.Year = await CalculateCategoryStatsAsync(budgets, category, BudgetPeriodType.Year, refDate);

        return result;
    }

    private async Task<BudgetStatsDto> CalculateCategoryStatsAsync(
        List<BudgetRecord> budgets,
        BudgetCategory category,
        BudgetPeriodType statType,
        DateTime referenceDate)
    {
        var result = new BudgetStatsDto
        {
            PeriodType = statType,
            Rate = 0,
            Current = 0,
            Limit = 0,
            Count = 0
        };

        // 获取当前分类下所有未停止的预算
        var relevant = budgets
            .Where(b => b.Category == category && !b.IsStopped)
            .ToList();

        if (relevant.Count == 0)
        {
            return result;
        }

        result.Count = relevant.Count;
        decimal totalCurrent = 0;
        decimal totalLimit = 0;

        foreach (var budget in relevant)
        {
            // 限额折算
            var itemLimit = budget.Limit;
            if (statType == BudgetPeriodType.Month && budget.Type == BudgetPeriodType.Year)
            {
                // 月度视图下，年度预算不参与限额计算
                itemLimit = 0;
            }
            else if (statType == BudgetPeriodType.Year && budget.Type == BudgetPeriodType.Month)
            {
                // 年度视图下，月度预算折算为年度
                itemLimit = budget.Limit * 12;
            }
            totalLimit += itemLimit;

            // 当前值累加
            var currentAmount = await CalculateCurrentAmountAsync(budget, referenceDate);
            if (budget.Type == statType)
            {
                totalCurrent += currentAmount;
            }
            else
            {
                // 如果周期不匹配
                if (statType == BudgetPeriodType.Year && budget.Type == BudgetPeriodType.Month)
                {
                    // 在年度视图下，月度预算计入其当前值（作为对年度目前的贡献）
                    totalCurrent += currentAmount;
                }
                // 月度视图下，年度预算的 current 不计入
            }
        }

        result.Limit = totalLimit;
        result.Current = totalCurrent;
        result.Rate = totalLimit > 0 ? (totalCurrent / totalLimit) * 100 : 0;

        return result;
    }

    public async Task<string> ArchiveBudgetsAsync(int year, int month)
    {
        var referenceDate = new DateTime(year, month, 1);
        var budgets = await GetListAsync(referenceDate);

        var addArchives = new List<BudgetArchive>();
        var updateArchives = new List<BudgetArchive>();
        foreach (var budget in budgets)
        {
            var archive = await budgetArchiveRepository.GetArchiveAsync(budget.Id, year, month);

            if (archive != null)
            {
                archive.RealizedAmount = budget.Current;
                archive.ArchiveDate = DateTime.Now;
                updateArchives.Add(archive);
            }
            else
            {
                archive = new BudgetArchive
                {
                    BudgetId = budget.Id,
                    BudgetType = budget.Type,
                    Year = year,
                    Month = month,
                    BudgetedAmount = budget.Limit,
                    RealizedAmount = budget.Current,
                    ArchiveDate = DateTime.Now
                };

                addArchives.Add(archive);
            }
        }

        if (addArchives.Count > 0)
        {
            if (!await budgetArchiveRepository.AddRangeAsync(addArchives))
            {
                return "保存预算归档失败";
            }
        }
        if (updateArchives.Count > 0)
        {
            if (!await budgetArchiveRepository.UpdateRangeAsync(updateArchives))
            {
                return "更新预算归档失败";
            }
        }

        _ = NotifyAsync(year, month);
        return string.Empty;
    }

    private async Task NotifyAsync(int year, int month)
    {
        try
        {
            var archives = await budgetArchiveRepository.GetListAsync(year, month);
            var budgets = await budgetRepository.GetAllAsync();
            var budgetMap = budgets.ToDictionary(b => b.Id, b => b);

            var archiveData = archives.Select(a =>
            {
                budgetMap.TryGetValue(a.BudgetId, out var br);
                var name = br?.Name ?? (a.BudgetId == -1 ? "年度存款" : a.BudgetId == -2 ? "月度存款" : "未知");
                return new
                {
                    Name = name,
                    Type = a.BudgetType.ToString(),
                    Limit = a.BudgetedAmount,
                    Actual = a.RealizedAmount,
                    Category = br?.Category.ToString() ?? (a.BudgetId < 0 ? "Savings" : "Unknown")
                };
            }).ToList();

            var yearTransactions = await transactionRecordRepository.ExecuteDynamicSqlAsync(
                $"""
                SELECT 
                  COUNT(*) AS TransactionCount, 
                  SUM(ABS(Amount)) AS TotalAmount, 
                  Type, 
                  Classify
                FROM TransactionRecord
                WHERE OccurredAt >= '{year}-01-01' 
                  AND OccurredAt < '{year + 1}-01-01'
                GROUP BY Type, Classify
                ORDER BY TotalAmount DESC
                """
            );
            var monthYear = new DateTime(year, month, 1).AddMonths(1);
            var monthTransactions = await transactionRecordRepository.ExecuteDynamicSqlAsync(
                $"""
                SELECT 
                  COUNT(*) AS TransactionCount, 
                  SUM(ABS(Amount)) AS TotalAmount, 
                  Type, 
                  Classify
                FROM TransactionRecord
                WHERE OccurredAt >= '{year}-{month:00}-01' 
                  AND OccurredAt < '{monthYear:yyyy-MM-dd}'
                GROUP BY Type, Classify
                ORDER BY TotalAmount DESC
                """
            );

            // 分析未被预算覆盖的分类 (仅针对支出类型 Type=0)
            var budgetedCategories = budgets
                .Where(b => !string.IsNullOrEmpty(b.SelectedCategories))
                .SelectMany(b => b.SelectedCategories.Split(','))
                .Distinct()
                .ToHashSet();

            var uncovered = monthTransactions
                .Where(t =>
                {
                    var dict = (IDictionary<string, object>)t;
                    var classify = dict["Classify"]?.ToString() ?? "";
                    var type = Convert.ToInt32(dict["Type"]);
                    return type == 0 && !budgetedCategories.Contains(classify);
                })
                .ToList();

            logger.LogInformation("预算执行数据{JSON}", JsonSerializer.Serialize(archiveData));
            logger.LogInformation("本月消费明细{JSON}", JsonSerializer.Serialize(monthTransactions));
            logger.LogInformation("全年累计消费概况{JSON}", JsonSerializer.Serialize(yearTransactions));
            logger.LogInformation("未被预算覆盖的分类{JSON}", JsonSerializer.Serialize(uncovered));

            var dataPrompt = $"""
            报告周期：{year}年{month}月
            账单数据说明：支出金额已取绝对值（TotalAmount 为正数表示支出/收入的总量）。

            1. 预算执行数据（JSON）：
            {JsonSerializer.Serialize(archiveData)}
            
            2. 本月消费明细（按分类, JSON）：
            {JsonSerializer.Serialize(monthTransactions)}
            
            3. 全年累计消费概况（按分类, JSON）：
            {JsonSerializer.Serialize(yearTransactions)}

            4. 未被任何预算覆盖的支出分类（JSON）：
            {JsonSerializer.Serialize(uncovered)}

            请生成一份专业且美观的预算执行分析报告，严格遵守以下要求：
            
            【内容要求】
            1. 概览：总结本月预算达成情况。
            2. 预算详情：使用 HTML 表格展示预算执行明细（预算项、预算额、实际额、使用/达成率、状态）。
            3. 超支/异常预警：重点分析超支项或支出异常的分类。
            4. 消费透视：针对“未被预算覆盖的支出”提供分析建议。分析这些账单产生的合理性，并评估是否需要为其中的大额或频发分类建立新预算。
            5. 改进建议：基于本月整体收入支出情况，给出下月预算调整或消费改进的专业化建议。
            6. 语言风格：专业、清晰、简洁，适合财务报告阅读。
            
            【格式要求】
            1. 使用HTML格式（移动端H5页面风格）
            2. 生成清晰的报告标题（基于用户问题）
            3. 使用表格展示统计数据（table > thead/tbody > tr > th/td）
            4. 使用合适的HTML标签：h2（标题）、h3（小节）、p（段落）、table（表格）、ul/li（列表）、strong（强调）
            5. 支出金额用 <span class='expense-value'>金额</span> 包裹
            6. 收入金额用 <span class='income-value'>金额</span> 包裹
            7. 重要结论用 <span class='highlight'>内容</span> 高亮
            
            【样式限制（重要）】
            8. 不要包含 html、body、head 标签
            9. 不要使用任何 style 属性或 <style> 标签
            10. 不要设置 background、background-color、color 等样式属性
            11. 不要使用 div 包裹大段内容
            
            直接输出纯净 HTML 内容，不要带有 Markdown 代码块包裹。
            """;

            var htmlReport = await openAiService.ChatAsync(dataPrompt);
            if (!string.IsNullOrEmpty(htmlReport))
            {
                await messageService.AddAsync(
                    title: $"{year}年{month}月 - 预算归档报告",
                    content: htmlReport,
                    type: MessageType.Html);
            }
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "生成预算执行通知报告失败");
        }
    }

    private async Task<decimal> CalculateCurrentAmountAsync(BudgetRecord budget, DateTime? now = null)
    {
        if (budget.IsStopped) return 0;

        var referenceDate = now ?? DateTime.Now;
        var (startDate, endDate) = GetPeriodRange(budget.StartDate, budget.Type, referenceDate);

        return await budgetRepository.GetCurrentAmountAsync(budget, startDate, endDate);
    }

    internal static (DateTime start, DateTime end) GetPeriodRange(DateTime startDate, BudgetPeriodType type, DateTime referenceDate)
    {
        DateTime start;
        DateTime end;

        if (type == BudgetPeriodType.Month)
        {
            start = new DateTime(referenceDate.Year, referenceDate.Month, 1);
            end = start.AddMonths(1).AddDays(-1).AddHours(23).AddMinutes(59).AddSeconds(59);
        }
        else if (type == BudgetPeriodType.Year)
        {
            start = new DateTime(referenceDate.Year, 1, 1);
            end = new DateTime(referenceDate.Year, 12, 31).AddHours(23).AddMinutes(59).AddSeconds(59);
        }
        else
        {
            start = startDate;
            end = DateTime.MaxValue;
        }

        return (start, end);
    }

    private async Task<BudgetResult?> GetVirtualSavingsDtoAsync(
        BudgetPeriodType periodType,
        DateTime? referenceDate = null,
        IEnumerable<BudgetRecord>? existingBudgets = null)
    {
        var allBudgets = existingBudgets;

        if (existingBudgets == null)
        {
            allBudgets = await budgetRepository.GetAllAsync();
        }

        if (allBudgets == null)
        {
            return null;
        }

        var date = referenceDate ?? DateTime.Now;

        decimal incomeLimitAtPeriod = 0;
        decimal expenseLimitAtPeriod = 0;

        var incomeItems = new List<(string Name, decimal Limit, decimal Factor, decimal Total)>();
        var expenseItems = new List<(string Name, decimal Limit, decimal Factor, decimal Total)>();

        foreach (var b in allBudgets)
        {
            if (b.IsStopped || b.Category == BudgetCategory.Savings) continue;

            // 折算系数：根据当前请求的 periodType (Year 或 Month)，将预算 b 的 Limit 折算过来
            decimal factor = 1.0m;

            if (periodType == BudgetPeriodType.Year)
            {
                factor = b.Type switch
                {
                    BudgetPeriodType.Month => 12,
                    BudgetPeriodType.Year => 1,
                    _ => 0
                };
            }
            else if (periodType == BudgetPeriodType.Month)
            {
                factor = b.Type switch
                {
                    BudgetPeriodType.Month => 1,
                    BudgetPeriodType.Year => 0,
                    _ => 0
                };
            }
            else
            {
                factor = 0; // 其他周期暂不计算虚拟存款
            }

            if (factor <= 0) continue;

            var subtotal = b.Limit * factor;
            if (b.Category == BudgetCategory.Income)
            {
                incomeLimitAtPeriod += subtotal;
                incomeItems.Add((b.Name, b.Limit, factor, subtotal));
            }
            else if (b.Category == BudgetCategory.Expense)
            {
                expenseLimitAtPeriod += subtotal;
                expenseItems.Add((b.Name, b.Limit, factor, subtotal));
            }
        }

        var description = new StringBuilder();
        description.Append("<h3>预算收入明细</h3>");
        if (incomeItems.Count == 0) description.Append("<p>无收入预算</p>");
        else
        {
            description.Append("<table><thead><tr><th>名称</th><th>金额</th><th>折算</th><th>合计</th></tr></thead><tbody>");
            foreach (var item in incomeItems)
            {
                description.Append($"<tr><td>{item.Name}</td><td>{item.Limit:N0}</td><td>x{item.Factor:0.##}</td><td><span class='income-value'>{item.Total:N0}</span></td></tr>");
            }
            description.Append("</tbody></table>");
        }
        description.Append($"<p>收入合计: <span class='income-value'><strong>{incomeLimitAtPeriod:N0}</strong></span></p>");

        description.Append("<h3>预算支出明细</h3>");
        if (expenseItems.Count == 0) description.Append("<p>无支出预算</p>");
        else
        {
            description.Append("<table><thead><tr><th>名称</th><th>金额</th><th>折算</th><th>合计</th></tr></thead><tbody>");
            foreach (var item in expenseItems)
            {
                description.Append($"<tr><td>{item.Name}</td><td>{item.Limit:N0}</td><td>x{item.Factor:0.##}</td><td><span class='expense-value'>{item.Total:N0}</span></td></tr>");
            }
            description.Append("</tbody></table>");
        }
        description.Append($"<p>支出合计: <span class='expense-value'><strong>{expenseLimitAtPeriod:N0}</strong></span></p>");

        description.Append("<h3>存款计划结论</h3>");
        description.Append($"<p>计划存款 = 收入 <span class='income-value'>{incomeLimitAtPeriod:N0}</span> - 支出 <span class='expense-value'>{expenseLimitAtPeriod:N0}</span></p>");
        description.Append($"<p>最终目标：<span class='highlight'><strong>{incomeLimitAtPeriod - expenseLimitAtPeriod:N0}</strong></span></p>");

        var savingsCategories = await configService.GetConfigByKeyAsync<string>("SavingsCategories") ?? string.Empty;
        var virtualBudget = new BudgetRecord
        {
            Id = periodType == BudgetPeriodType.Year ? -1 : -2,
            Name = periodType == BudgetPeriodType.Year ? "年度存款" : "月度存款",
            Category = BudgetCategory.Savings,
            Type = periodType,
            Limit = incomeLimitAtPeriod - expenseLimitAtPeriod,
            StartDate = periodType == BudgetPeriodType.Year 
                ? new DateTime(date.Year, 1, 1) 
                : new DateTime(date.Year, date.Month, 1),
            SelectedCategories = savingsCategories
        };

        // 计算实际发生的 收入 - 支出
        var current = await CalculateCurrentAmountAsync(new BudgetRecord
        {
            Category = virtualBudget.Category,
            Type = virtualBudget.Type,
            SelectedCategories = virtualBudget.SelectedCategories,
            StartDate = virtualBudget.StartDate,
        }, date);

        return BudgetResult.FromEntity(virtualBudget, current, date, description.ToString());
    }
}

public record BudgetResult
{
    public long Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public BudgetPeriodType Type { get; set; }
    public decimal Limit { get; set; }
    public decimal Current { get; set; }
    public BudgetCategory Category { get; set; }
    public string[] SelectedCategories { get; set; } = Array.Empty<string>();
    public bool IsStopped { get; set; }
    public string StartDate { get; set; } = string.Empty;
    public string Period { get; set; } = string.Empty;
    public DateTime? PeriodStart { get; set; }
    public DateTime? PeriodEnd { get; set; }

    public string Description { get; set; } = string.Empty;

    public static BudgetResult FromEntity(
        BudgetRecord entity,
        decimal currentAmount = 0,
        DateTime? referenceDate = null,
        string description = "")
    {
        var date = referenceDate ?? DateTime.Now;
        var (start, end) = BudgetService.GetPeriodRange(entity.StartDate, entity.Type, date);

        return new BudgetResult
        {
            Id = entity.Id,
            Name = entity.Name,
            Type = entity.Type,
            Limit = entity.Limit,
            Current = currentAmount,
            Category = entity.Category,
            SelectedCategories = string.IsNullOrEmpty(entity.SelectedCategories)
                ? Array.Empty<string>()
                : entity.SelectedCategories.Split(','),
            IsStopped = entity.IsStopped,
            StartDate = entity.StartDate.ToString("yyyy-MM-dd"),
            Period = entity.Type switch
            {
                BudgetPeriodType.Year => $"{start:yy}年",
                BudgetPeriodType.Month => $"{start:yy}年第{start.Month}月",
                _ => $"{start:yyyy-MM-dd} ~ {end:yyyy-MM-dd}"
            },
            PeriodStart = start,
            PeriodEnd = end,
            Description = description
        };
    }
}
/// <summary>
/// 预算统计结果 DTO
/// </summary>
public class BudgetStatsDto
{
    /// <summary>
    /// 统计周期类型（Month/Year）
    /// </summary>
    public BudgetPeriodType PeriodType { get; set; }

    /// <summary>
    /// 使用率百分比（0-100）
    /// </summary>
    public decimal Rate { get; set; }

    /// <summary>
    /// 实际金额
    /// </summary>
    public decimal Current { get; set; }

    /// <summary>
    /// 目标/限额金额
    /// </summary>
    public decimal Limit { get; set; }

    /// <summary>
    /// 预算项数量
    /// </summary>
    public int Count { get; set; }
}

/// <summary>
/// 分类统计结果
/// </summary>
public class BudgetCategoryStats
{
    /// <summary>
    /// 月度统计
    /// </summary>
    public BudgetStatsDto Month { get; set; } = new();

    /// <summary>
    /// 年度统计
    /// </summary>
    public BudgetStatsDto Year { get; set; } = new();
}