using YD_Event.Core.Enum;

namespace YD_Event.Core.Domain.Pricing;

/// <summary>
/// 赛事定价计算服务
/// 所有金额计算均以此服务为准，确保计算结果的一致性
/// </summary>
public static class EventPricingService
{
    /// <summary>
    /// 赛事基础定价（元）
    /// </summary>
    public const decimal EventBasePrice = 1000m;

    /// <summary>
    /// 项目A定价（元）
    /// </summary>
    public const decimal ProjectAPrice = 500m;

    /// <summary>
    /// 项目B定价（元）
    /// </summary>
    public const decimal ProjectBPrice = 1000m;

    /// <summary>
    /// 定价计算输入参数
    /// </summary>
    public class PricingInput
    {
        /// <summary>
        /// 收费模式
        /// </summary>
        public ChargeMode ChargeMode { get; set; }

        /// <summary>
        /// 参赛人数
        /// </summary>
        public int ParticipantCount { get; set; }

        /// <summary>
        /// 项目列表（单价项目模式使用）
        /// </summary>
        public List<ProjectPricingInfo> Projects { get; set; } = new List<ProjectPricingInfo>();
    }

    /// <summary>
    /// 项目定价信息
    /// </summary>
    public class ProjectPricingInfo
    {
        /// <summary>
        /// 项目ID
        /// </summary>
        public long ProjectId { get; set; }

        /// <summary>
        /// 项目名称
        /// </summary>
        public string ProjectName { get; set; } = string.Empty;

        /// <summary>
        /// 项目单价（元）
        /// </summary>
        public decimal UnitPrice { get; set; }
    }

    /// <summary>
    /// 定价计算结果
    /// </summary>
    public class PricingResult
    {
        /// <summary>
        /// 总金额（精确到分）
        /// </summary>
        public decimal TotalAmount { get; set; }

        /// <summary>
        /// 总人数
        /// </summary>
        public int TotalPersonCount { get; set; }

        /// <summary>
        /// 费用明细
        /// </summary>
        public List<PricingDetailItem> Details { get; set; } = new List<PricingDetailItem>();

        /// <summary>
        /// 计算日志（用于审计）
        /// </summary>
        public List<string> CalculationLogs { get; set; } = new List<string>();
    }

    /// <summary>
    /// 费用明细项
    /// </summary>
    public class PricingDetailItem
    {
        /// <summary>
        /// 项目名称
        /// </summary>
        public string ItemName { get; set; } = string.Empty;

        /// <summary>
        /// 单价
        /// </summary>
        public decimal UnitPrice { get; set; }

        /// <summary>
        /// 数量
        /// </summary>
        public int Quantity { get; set; }

        /// <summary>
        /// 小计
        /// </summary>
        public decimal Subtotal { get; set; }

        /// <summary>
        /// 备注
        /// </summary>
        public string? Remark { get; set; }
    }

    /// <summary>
    /// 计算赛事报名费用
    /// </summary>
    /// <param name="input">定价计算输入</param>
    /// <returns>定价计算结果</returns>
    public static PricingResult Calculate(PricingInput input)
    {
        var result = new PricingResult
        {
            TotalPersonCount = input.ParticipantCount
        };

        result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 开始计算费用，收费模式: {input.ChargeMode}, 人数: {input.ParticipantCount}");

        switch (input.ChargeMode)
        {
            case ChargeMode.Free:
                CalculateFreeMode(result);
                break;
            case ChargeMode.FixedPrice:
                CalculateFixedPriceMode(result, input.ParticipantCount);
                break;
            case ChargeMode.UnitPriceEvent:
                CalculateUnitPriceEventMode(result, input.ParticipantCount);
                break;
            case ChargeMode.UnitPriceProject:
                CalculateUnitPriceProjectMode(result, input.Projects, input.ParticipantCount);
                break;
        }

        // 确保金额精确到分
        result.TotalAmount = Math.Round(result.TotalAmount, 2, MidpointRounding.AwayFromZero);
        result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 最终总金额: {result.TotalAmount:F2} 元");

        return result;
    }

    /// <summary>
    /// 免费模式
    /// </summary>
    private static void CalculateFreeMode(PricingResult result)
    {
        result.TotalAmount = 0;
        result.Details.Add(new PricingDetailItem
        {
            ItemName = "报名费",
            UnitPrice = 0,
            Quantity = 1,
            Subtotal = 0,
            Remark = "免费"
        });
        result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 免费模式，总金额: 0 元");
    }

    /// <summary>
    /// 定价（赛事）模式：固定为1000元/场，无论参赛主体是个人还是单位，也无论参赛项目数量多少，均统一按1000元计算
    /// </summary>
    private static void CalculateFixedPriceMode(PricingResult result, int participantCount)
    {
        var price = EventBasePrice;
        result.TotalAmount = price;
        result.Details.Add(new PricingDetailItem
        {
            ItemName = "赛事报名费",
            UnitPrice = price,
            Quantity = 1,
            Subtotal = price,
            Remark = $"固定价格 {EventBasePrice:F2} 元/场，参赛人数: {participantCount} 人"
        });
        result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 定价（赛事）模式: 固定价格 {EventBasePrice:F2} 元/场");
    }

    /// <summary>
    /// 单价（赛事）模式：赛事基础定价为1000元，个人参赛按1000元计算；团队参赛按人数乘以1000元计算
    /// </summary>
    private static void CalculateUnitPriceEventMode(PricingResult result, int participantCount)
    {
        var unitPrice = EventBasePrice;
        var totalAmount = unitPrice * participantCount;
        result.TotalAmount = totalAmount;
        result.Details.Add(new PricingDetailItem
        {
            ItemName = "赛事报名费",
            UnitPrice = unitPrice,
            Quantity = participantCount,
            Subtotal = totalAmount,
            Remark = participantCount == 1 
                ? $"个人参赛 {unitPrice:F2} 元" 
                : $"团队参赛 {unitPrice:F2} 元/人 × {participantCount} 人"
        });
        result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 单价（赛事）模式: {unitPrice:F2} 元/人 × {participantCount} 人 = {totalAmount:F2} 元");
    }

    /// <summary>
    /// 单价（项目）模式：按具体项目定价计算，个人参加多项时，费用为各项单价之和；团队参加多项时，费用为（各项单价之和）×团队人数
    /// </summary>
    private static void CalculateUnitPriceProjectMode(PricingResult result, List<ProjectPricingInfo> projects, int participantCount)
    {
        decimal totalProjectPrice = 0;

        foreach (var project in projects)
        {
            totalProjectPrice += project.UnitPrice;
            result.Details.Add(new PricingDetailItem
            {
                ItemName = project.ProjectName,
                UnitPrice = project.UnitPrice,
                Quantity = 1,
                Subtotal = project.UnitPrice,
                Remark = "项目单价"
            });
            result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 项目: {project.ProjectName}, 单价: {project.UnitPrice:F2} 元");
        }

        var totalAmount = totalProjectPrice * participantCount;
        result.TotalAmount = totalAmount;

        // 添加汇总项
        result.Details.Add(new PricingDetailItem
        {
            ItemName = participantCount == 1 ? "项目总价" : "项目总价 × 人数",
            UnitPrice = totalProjectPrice,
            Quantity = participantCount,
            Subtotal = totalAmount,
            Remark = participantCount == 1 
                ? $"个人参赛，项目总价 {totalProjectPrice:F2} 元" 
                : $"团队参赛，({totalProjectPrice:F2} 元) × {participantCount} 人"
        });
        result.CalculationLogs.Add($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] 单价（项目）模式: 项目总价 {totalProjectPrice:F2} 元 × {participantCount} 人 = {totalAmount:F2} 元");
    }
}