package vehicle

import (
	"errors"
	"math"
	"wails-app/internal/dao"
	"wails-app/internal/global"
	"wails-app/internal/model/vehicle/request"
)

type FeeConfigService struct{}

// validateFeeRules 校验收费规则的数值合法性，防止脏配置静默改变计费。
// 全零配置允许（显式免费），但单位时间必须大于 0，金额必须非负且有限。
func validateFeeRules(req request.FeeConfigCreate) error {
	if req.StartTime < 0 {
		return errors.New("免费时长不能为负数")
	}
	if req.UnitTime <= 0 {
		return errors.New("单位时间必须大于0分钟")
	}
	if req.StartFee < 0 || math.IsNaN(req.StartFee) || math.IsInf(req.StartFee, 0) {
		return errors.New("起步价必须为非负有限数值")
	}
	if req.UnitFee < 0 || math.IsNaN(req.UnitFee) || math.IsInf(req.UnitFee, 0) {
		return errors.New("单位费用必须为非负有限数值")
	}
	if req.DailyMaxFee < 0 || math.IsNaN(req.DailyMaxFee) || math.IsInf(req.DailyMaxFee, 0) {
		return errors.New("日封顶金额必须为非负有限数值")
	}
	if req.DailyMaxFee > 0 && req.DailyMaxFee < req.StartFee {
		return errors.New("日封顶金额不能低于起步价")
	}
	if req.VIPDiscount <= 0 || req.VIPDiscount > 1 || math.IsNaN(req.VIPDiscount) || math.IsInf(req.VIPDiscount, 0) {
		return errors.New("VIP折扣必须在(0,1]区间，如0.8表示八折")
	}
	if req.FreeExitMinutes < 0 {
		return errors.New("缴费后免费离场分钟数不能为负数")
	}
	return nil
}

// CreateFeeConfig 创建收费配置
func (s *FeeConfigService) CreateFeeConfig(req request.FeeConfigCreate) error {
	if err := validateFeeRules(req); err != nil {
		return err
	}
	// 检查车辆类型是否存在
	var vehicleType dao.VehicleType
	result := global.GVA_DB.First(&vehicleType, req.VehicleTypeID)
	if result.RowsAffected == 0 {
		return errors.New("车辆类型不存在")
	}

	// 检查车辆类型是否已存在收费配置
	var existingConfig dao.FeeConfig
	result = global.GVA_DB.Where("vehicle_type_id = ?", req.VehicleTypeID).First(&existingConfig)
	if result.RowsAffected > 0 {
		return errors.New("该车辆类型的收费配置已存在")
	}

	config := dao.FeeConfig{
		VehicleTypeID:   req.VehicleTypeID,
		StartTime:       req.StartTime,
		StartFee:        req.StartFee,
		UnitTime:        req.UnitTime,
		UnitFee:         req.UnitFee,
		DailyMaxFee:     req.DailyMaxFee,
		FreeExitMinutes: req.FreeExitMinutes,
		IsVIPFree:       req.IsVIPFree,
		VIPDiscount:     req.VIPDiscount,
		Description:     req.Description,
	}

	return global.GVA_DB.Create(&config).Error
}

// UpdateFeeConfig 更新收费配置
func (s *FeeConfigService) UpdateFeeConfig(req request.FeeConfigUpdate) error {
	if err := validateFeeRules(request.FeeConfigCreate{
		VehicleTypeID:   req.VehicleTypeID,
		StartTime:       req.StartTime,
		StartFee:        req.StartFee,
		UnitTime:        req.UnitTime,
		UnitFee:         req.UnitFee,
		DailyMaxFee:     req.DailyMaxFee,
		FreeExitMinutes: req.FreeExitMinutes,
		IsVIPFree:       req.IsVIPFree,
		VIPDiscount:     req.VIPDiscount,
		Description:     req.Description,
	}); err != nil {
		return err
	}
	var config dao.FeeConfig
	result := global.GVA_DB.First(&config, req.ID)
	if result.RowsAffected == 0 {
		return errors.New("收费配置不存在")
	}

	// 检查车辆类型是否存在
	var vehicleType dao.VehicleType
	result = global.GVA_DB.First(&vehicleType, req.VehicleTypeID)
	if result.RowsAffected == 0 {
		return errors.New("车辆类型不存在")
	}

	// 检查车辆类型是否被其他配置使用
	var existingConfig dao.FeeConfig
	result = global.GVA_DB.Where("vehicle_type_id = ? AND id != ?", req.VehicleTypeID, req.ID).First(&existingConfig)
	if result.RowsAffected > 0 {
		return errors.New("该车辆类型的收费配置已存在")
	}

	config.VehicleTypeID = req.VehicleTypeID
	config.StartTime = req.StartTime
	config.StartFee = req.StartFee
	config.UnitTime = req.UnitTime
	config.UnitFee = req.UnitFee
	config.DailyMaxFee = req.DailyMaxFee
	config.FreeExitMinutes = req.FreeExitMinutes
	config.IsVIPFree = req.IsVIPFree
	config.VIPDiscount = req.VIPDiscount
	config.Description = req.Description

	return global.GVA_DB.Save(&config).Error
}

// GetFeeConfigByID 根据ID获取收费配置
func (s *FeeConfigService) GetFeeConfigByID(id uint) (dao.FeeConfig, error) {
	var config dao.FeeConfig
	result := global.GVA_DB.First(&config, id)
	if result.RowsAffected == 0 {
		return dao.FeeConfig{}, errors.New("收费配置不存在")
	}
	return config, nil
}

// GetFeeConfigByVehicleType 根据车辆类型ID获取收费配置
func (s *FeeConfigService) GetFeeConfigByVehicleType(vehicleTypeID uint) (dao.FeeConfig, error) {
	var config dao.FeeConfig
	result := global.GVA_DB.Where("vehicle_type_id = ?", vehicleTypeID).First(&config)
	if result.RowsAffected == 0 {
		return dao.FeeConfig{}, errors.New("收费配置不存在")
	}
	return config, nil
}

// ListFeeConfigs 获取收费配置列表
func (s *FeeConfigService) ListFeeConfigs(req request.FeeConfigQuery) (int64, []dao.FeeConfig, error) {
	var configs []dao.FeeConfig
	var total int64

	query := global.GVA_DB.Model(&dao.FeeConfig{})

	if req.VehicleTypeID > 0 {
		query = query.Where("vehicle_type_id = ?", req.VehicleTypeID)
	}

	// 计算总数
	query.Count(&total)

	// 分页兜底（gin 不解析 default 标签，Page/PageSize 可能为 0 或负数）
	if req.Page <= 0 {
		req.Page = 1
	}
	if req.PageSize <= 0 {
		req.PageSize = 10
	}
	offset := (req.Page - 1) * req.PageSize
	result := query.Offset(offset).Limit(req.PageSize).Preload("VehicleType").Find(&configs)
	if result.Error != nil {
		return 0, nil, result.Error
	}

	return total, configs, nil
}

// DeleteFeeConfig 删除收费配置
func (s *FeeConfigService) DeleteFeeConfig(id uint) error {
	result := global.GVA_DB.Delete(&dao.FeeConfig{}, id)
	if result.RowsAffected == 0 {
		return errors.New("收费配置不存在")
	}
	return result.Error
}