package promo

import (
	"context"
	"errors"

	"github.com/redis/go-redis/v9"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

type RuleWithPrice struct {
	Rule
	PromoPrice int64 `gorm:"column:promo_price"`
}

type RuleFilter struct {
	Page    int
	Size    int
	Type    string
	Enabled *bool
	Search  string
}

type SubscribePromoFilter struct {
	Page        int
	Size        int
	PromoRuleId int64
}

type UsageFilter struct {
	Page        int
	Size        int
	PromoRuleId int64
	UserId      int64
	SubscribeId int64
	OrderNo     string
}

type Model interface {
	QueryEligibleRules(ctx context.Context, subscribeId int64) ([]*RuleWithPrice, error)
	InsertUsage(ctx context.Context, data *Usage, tx ...*gorm.DB) error
	InsertRule(ctx context.Context, data *Rule) error
	FindRule(ctx context.Context, id int64) (*Rule, error)
	UpdateRule(ctx context.Context, data *Rule) error
	DeleteRule(ctx context.Context, id int64) error
	QueryRuleList(ctx context.Context, filter RuleFilter) (int64, []*Rule, error)
	UpsertSubscribePromos(ctx context.Context, data []*SubscribePromo) error
	FindSubscribePromo(ctx context.Context, id int64) (*SubscribePromo, error)
	DeleteSubscribePromo(ctx context.Context, id int64) error
	QuerySubscribePromoList(ctx context.Context, filter SubscribePromoFilter) (int64, []*SubscribePromo, error)
	QueryUsageList(ctx context.Context, filter UsageFilter) (int64, []*Usage, error)
}

type defaultPromoModel struct {
	db *gorm.DB
}

func NewModel(db *gorm.DB, _ *redis.Client) Model {
	return &defaultPromoModel{db: db}
}

func normalizePage(page, size int) (int, int) {
	if page <= 0 {
		page = 1
	}
	if size <= 0 {
		size = 10
	}
	if size > 100 {
		size = 100
	}
	return page, size
}

func (m *defaultPromoModel) QueryEligibleRules(ctx context.Context, subscribeId int64) ([]*RuleWithPrice, error) {
	var list []*RuleWithPrice
	err := m.db.WithContext(ctx).
		Table("promo_rule AS pr").
		Select("pr.*, sp.promo_price").
		Joins("JOIN subscribe_promo AS sp ON sp.promo_rule_id = pr.id").
		Where("sp.subscribe_id = ? AND sp.promo_price > 0 AND pr.enabled = ?", subscribeId, true).
		Where("pr.deleted_at IS NULL").
		Order("pr.priority DESC").
		Order("pr.id ASC").
		Find(&list).Error
	return list, err
}

func (m *defaultPromoModel) InsertUsage(ctx context.Context, data *Usage, tx ...*gorm.DB) error {
	db := m.db.WithContext(ctx)
	if len(tx) > 0 {
		db = tx[0].WithContext(ctx)
	}
	return db.Model(&Usage{}).Create(data).Error
}

func (m *defaultPromoModel) InsertRule(ctx context.Context, data *Rule) error {
	return m.db.WithContext(ctx).Create(data).Error
}

func (m *defaultPromoModel) FindRule(ctx context.Context, id int64) (*Rule, error) {
	var data Rule
	err := m.db.WithContext(ctx).Model(&Rule{}).Where("id = ?", id).First(&data).Error
	return &data, err
}

func (m *defaultPromoModel) UpdateRule(ctx context.Context, data *Rule) error {
	return m.db.WithContext(ctx).Save(data).Error
}

func (m *defaultPromoModel) DeleteRule(ctx context.Context, id int64) error {
	result := m.db.WithContext(ctx).Delete(&Rule{}, id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return gorm.ErrRecordNotFound
	}
	return nil
}

func (m *defaultPromoModel) QueryRuleList(ctx context.Context, filter RuleFilter) (int64, []*Rule, error) {
	page, size := normalizePage(filter.Page, filter.Size)
	var total int64
	var list []*Rule

	query := m.db.WithContext(ctx).Model(&Rule{})
	if filter.Type != "" {
		query = query.Where("type = ?", filter.Type)
	}
	if filter.Enabled != nil {
		query = query.Where("enabled = ?", *filter.Enabled)
	}
	if filter.Search != "" {
		search := "%" + filter.Search + "%"
		query = query.Where("name LIKE ?", search)
	}
	if err := query.Count(&total).Error; err != nil {
		return 0, nil, err
	}
	err := query.Order("priority DESC").Order("id DESC").
		Limit(size).Offset((page - 1) * size).
		Find(&list).Error
	return total, list, err
}

func (m *defaultPromoModel) UpsertSubscribePromos(ctx context.Context, data []*SubscribePromo) error {
	if len(data) == 0 {
		return nil
	}
	return m.db.WithContext(ctx).Clauses(clause.OnConflict{
		Columns:   []clause.Column{{Name: "subscribe_id"}, {Name: "promo_rule_id"}},
		DoUpdates: clause.AssignmentColumns([]string{"promo_price", "updated_at"}),
	}).Create(&data).Error
}

func (m *defaultPromoModel) FindSubscribePromo(ctx context.Context, id int64) (*SubscribePromo, error) {
	var data SubscribePromo
	err := m.db.WithContext(ctx).Model(&SubscribePromo{}).Where("id = ?", id).First(&data).Error
	return &data, err
}

func (m *defaultPromoModel) DeleteSubscribePromo(ctx context.Context, id int64) error {
	result := m.db.WithContext(ctx).Delete(&SubscribePromo{}, id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return gorm.ErrRecordNotFound
	}
	return nil
}

func (m *defaultPromoModel) QuerySubscribePromoList(ctx context.Context, filter SubscribePromoFilter) (int64, []*SubscribePromo, error) {
	page, size := normalizePage(filter.Page, filter.Size)
	var total int64
	var list []*SubscribePromo

	query := m.db.WithContext(ctx).Model(&SubscribePromo{})
	if filter.PromoRuleId > 0 {
		query = query.Where("promo_rule_id = ?", filter.PromoRuleId)
	}
	if err := query.Count(&total).Error; err != nil {
		return 0, nil, err
	}
	err := query.Order("id DESC").Limit(size).Offset((page - 1) * size).Find(&list).Error
	return total, list, err
}

func (m *defaultPromoModel) QueryUsageList(ctx context.Context, filter UsageFilter) (int64, []*Usage, error) {
	page, size := normalizePage(filter.Page, filter.Size)
	var total int64
	var list []*Usage

	query := m.db.WithContext(ctx).Model(&Usage{})
	if filter.PromoRuleId > 0 {
		query = query.Where("promo_rule_id = ?", filter.PromoRuleId)
	}
	if filter.UserId > 0 {
		query = query.Where("user_id = ?", filter.UserId)
	}
	if filter.SubscribeId > 0 {
		query = query.Where("subscribe_id = ?", filter.SubscribeId)
	}
	if filter.OrderNo != "" {
		query = query.Where("order_no LIKE ?", "%"+filter.OrderNo+"%")
	}
	if err := query.Count(&total).Error; err != nil {
		return 0, nil, err
	}
	err := query.Order("id DESC").Limit(size).Offset((page - 1) * size).Find(&list).Error
	return total, list, err
}

func IsNotFound(err error) bool {
	return errors.Is(err, gorm.ErrRecordNotFound)
}