package distribution

import (
	"context"
	"errors"
	"strings"
	"time"

	"hfb_sys/backend/internal/model"

	"gorm.io/gorm"
)

var (
	ErrSiteNotFound            = errors.New("distribution site not found")
	ErrRuleNotFound            = errors.New("distribution rule not found")
	ErrOrderNotFound           = errors.New("distribution order not found")
	ErrInvalidOrderKind        = errors.New("invalid distribution order kind")
	ErrAccountDisplayNotFound  = errors.New("distribution account display not found")
	ErrPaymentChannelNotFound  = errors.New("distribution payment channel not found")
	ErrInvalidPeriod           = errors.New("invalid distribution settlement period")
	ErrSettlementBatchNotFound = errors.New("distribution settlement batch not found")
	ErrBatchAlreadySettled     = errors.New("distribution settlement batch already settled")
	ErrSiteAccessDenied        = errors.New("distribution site access denied")
)

type Repository struct{ db *gorm.DB }

func NewRepository(db *gorm.DB) *Repository { return &Repository{db: db} }

func (r *Repository) ScopeSiteID(ctx context.Context, adminID, requested uint64) (uint64, error) {
	if adminID == 0 {
		return requested, nil
	}
	var members []model.DistributionSiteMember
	if err := r.db.WithContext(ctx).Where("admin_user_id = ? AND status = 'active'", adminID).Find(&members).Error; err != nil {
		return 0, err
	}
	if len(members) == 0 {
		return requested, nil
	}
	if requested > 0 {
		for _, member := range members {
			if member.SiteID == requested {
				return requested, nil
			}
		}
		return 0, ErrSiteAccessDenied
	}
	if len(members) == 1 {
		return members[0].SiteID, nil
	}
	return 0, nil
}

func (r *Repository) ListSites(ctx context.Context) ([]SiteDTO, error) {
	var rows []model.DistributionSite
	if err := r.db.WithContext(ctx).Order("id ASC").Find(&rows).Error; err != nil {
		return nil, err
	}
	items := make([]SiteDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, siteDTO(row))
	}
	return items, nil
}

func (r *Repository) FindSite(ctx context.Context, id uint64) (*SiteDTO, error) {
	var row model.DistributionSite
	if err := r.db.WithContext(ctx).First(&row, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrSiteNotFound
		}
		return nil, err
	}
	item := siteDTO(row)
	return &item, nil
}

func (r *Repository) CreateSite(ctx context.Context, req CreateSiteRequest) (*SiteDTO, error) {
	row := model.DistributionSite{
		SiteCode: strings.TrimSpace(req.SiteCode), SiteName: strings.TrimSpace(req.SiteName), Domain: strings.TrimSpace(req.Domain),
		Status: "active", DisplayAccountEnabled: true, TaxRateBPS: 100,
	}
	if req.DisplayAccountEnabled != nil {
		row.DisplayAccountEnabled = *req.DisplayAccountEnabled
	}
	if req.DefaultSupportGroupID != nil {
		row.DefaultSupportGroupID = req.DefaultSupportGroupID
	}
	if req.TaxEnabled != nil {
		row.TaxEnabled = *req.TaxEnabled
	}
	if req.TaxRateBPS != nil {
		row.TaxRateBPS = *req.TaxRateBPS
	}
	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
		return nil, err
	}
	item := siteDTO(row)
	return &item, nil
}

func (r *Repository) UpdateSite(ctx context.Context, id uint64, req UpdateSiteRequest) (*SiteDTO, error) {
	var row model.DistributionSite
	if err := r.db.WithContext(ctx).First(&row, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrSiteNotFound
		}
		return nil, err
	}
	if req.SiteName != nil {
		row.SiteName = strings.TrimSpace(*req.SiteName)
	}
	if req.Domain != nil {
		row.Domain = strings.TrimSpace(*req.Domain)
	}
	if req.Status != nil {
		row.Status = strings.TrimSpace(*req.Status)
	}
	if req.DisplayAccountEnabled != nil {
		row.DisplayAccountEnabled = *req.DisplayAccountEnabled
	}
	if req.DefaultSupportGroupID != nil {
		row.DefaultSupportGroupID = req.DefaultSupportGroupID
	}
	if req.TaxEnabled != nil {
		row.TaxEnabled = *req.TaxEnabled
	}
	if req.TaxRateBPS != nil {
		row.TaxRateBPS = *req.TaxRateBPS
	}
	if err := r.db.WithContext(ctx).Save(&row).Error; err != nil {
		return nil, err
	}
	item := siteDTO(row)
	return &item, nil
}

func (r *Repository) ListRules(ctx context.Context, siteID *uint64, mode string) ([]RuleDTO, error) {
	db := r.db.WithContext(ctx).Model(&model.DistributionRuleVersion{}).Order("effective_from DESC, id DESC")
	if siteID == nil {
		db = db.Where("site_id IS NULL")
	} else {
		db = db.Where("site_id = ?", *siteID)
	}
	if mode = strings.TrimSpace(mode); mode != "" {
		db = db.Where("mode = ?", mode)
	}
	var rows []model.DistributionRuleVersion
	if err := db.Find(&rows).Error; err != nil {
		return nil, err
	}
	items := make([]RuleDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, ruleDTO(row))
	}
	return items, nil
}

func (r *Repository) CreateRule(ctx context.Context, adminID uint64, req CreateRuleRequest) (*RuleDTO, error) {
	version := 1
	var maxVersion int
	db := r.db.WithContext(ctx).Model(&model.DistributionRuleVersion{}).Where("mode = ?", req.Mode)
	if req.SiteID == nil {
		db = db.Where("site_id IS NULL")
	} else {
		db = db.Where("site_id = ?", *req.SiteID)
	}
	if err := db.Select("COALESCE(MAX(version), 0)").Scan(&maxVersion).Error; err != nil {
		return nil, err
	}
	version = maxVersion + 1
	effectiveFrom := req.EffectiveFrom
	if effectiveFrom.IsZero() {
		effectiveFrom = time.Now()
	}
	row := model.DistributionRuleVersion{
		SiteID: req.SiteID, Mode: strings.TrimSpace(req.Mode), Version: version, Status: "draft",
		PlatformReceiveRatio: req.PlatformReceiveRatio, PlatformSellRatio: req.PlatformSellRatio,
		DistributorReceiveRatio: req.DistributorReceiveRatio, DistributorSellRatio: req.DistributorSellRatio,
		DistributorARatio: req.DistributorARatio, DistributorBRatio: req.DistributorBRatio,
		ServiceFeeValue: req.ServiceFeeValue, ServiceFeeUnit: strings.TrimSpace(req.ServiceFeeUnit),
		PaymentFeeBPS: req.PaymentFeeBPS, TaxEnabled: req.TaxEnabled, TaxRateBPS: req.TaxRateBPS,
		EffectiveFrom: effectiveFrom, CreatedBy: &adminID,
	}
	if row.PaymentFeeBPS == 0 {
		row.PaymentFeeBPS = 50
	}
	if row.TaxRateBPS == 0 {
		row.TaxRateBPS = 100
	}
	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
		return nil, err
	}
	item := ruleDTO(row)
	return &item, nil
}

func (r *Repository) UpdateRuleStatus(ctx context.Context, id uint64, status string) (*RuleDTO, error) {
	var row model.DistributionRuleVersion
	if err := r.db.WithContext(ctx).First(&row, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrRuleNotFound
		}
		return nil, err
	}
	row.Status = strings.TrimSpace(status)
	if err := r.db.WithContext(ctx).Save(&row).Error; err != nil {
		return nil, err
	}
	item := ruleDTO(row)
	return &item, nil
}

func siteDTO(row model.DistributionSite) SiteDTO {
	return SiteDTO{ID: row.ID, SiteCode: row.SiteCode, SiteName: row.SiteName, Domain: row.Domain, Status: row.Status, DisplayAccountEnabled: row.DisplayAccountEnabled, DefaultSupportGroupID: row.DefaultSupportGroupID, TaxEnabled: row.TaxEnabled, TaxRateBPS: row.TaxRateBPS, CreatedAt: row.CreatedAt, UpdatedAt: row.UpdatedAt}
}

func ruleDTO(row model.DistributionRuleVersion) RuleDTO {
	return RuleDTO{ID: row.ID, SiteID: row.SiteID, Mode: row.Mode, Version: row.Version, Status: row.Status, PlatformReceiveRatio: row.PlatformReceiveRatio, PlatformSellRatio: row.PlatformSellRatio, DistributorReceiveRatio: row.DistributorReceiveRatio, DistributorSellRatio: row.DistributorSellRatio, DistributorARatio: row.DistributorARatio, DistributorBRatio: row.DistributorBRatio, ServiceFeeValue: row.ServiceFeeValue, ServiceFeeUnit: row.ServiceFeeUnit, PaymentFeeBPS: row.PaymentFeeBPS, TaxEnabled: row.TaxEnabled, TaxRateBPS: row.TaxRateBPS, EffectiveFrom: row.EffectiveFrom, EffectiveTo: row.EffectiveTo, CreatedBy: row.CreatedBy, CreatedAt: row.CreatedAt}
}

func (r *Repository) ListOrders(ctx context.Context, query DistributionOrderListQuery) (*DistributionOrderPage, error) {
	page, size := query.Page, query.Size
	if page < 1 {
		page = 1
	}
	if size < 1 {
		size = 20
	}
	if size > 100 {
		size = 100
	}
	base := r.db.WithContext(ctx).Table("rental_orders ro").Joins("JOIN distribution_order_financials f ON f.order_id = ro.id")
	if query.SiteID > 0 {
		base = base.Where("ro.distribution_site_id = ?", query.SiteID)
	}
	if query.Status != "" {
		base = base.Where("ro.status = ?", query.Status)
	}
	switch strings.TrimSpace(query.Kind) {
	case "sold":
		base = base.Where("EXISTS (SELECT 1 FROM distribution_order_parties p WHERE p.order_id = ro.id AND p.party_role IN ('distributor_sell','distributor_b'))")
	case "receive":
		base = base.Where("EXISTS (SELECT 1 FROM distribution_order_parties p WHERE p.order_id = ro.id AND p.party_role IN ('distributor_receive','distributor_a'))")
	case "", "all":
	default:
		return nil, ErrInvalidOrderKind
	}
	var total int64
	if err := base.Session(&gorm.Session{}).Select("ro.id").Count(&total).Error; err != nil {
		return nil, err
	}
	items := make([]DistributionOrderDTO, 0)
	selectSQL := "ro.id AS order_id, ro.order_no, ro.distribution_site_id AS site_id, ro.listing_id, ro.account_id, ro.owner_id, ro.renter_id, ro.status, ro.handoff_status, ro.refund_status, ro.settlement_status, ro.distribution_mode, f.gross_paid_amount_cent, f.refund_amount_cent, f.net_paid_amount_cent, f.payment_fee_cent, f.service_fee_cent, f.markup_amount_cent, f.tax_amount_cent, f.split_base_amount_cent, ro.created_at"
	if err := base.Select(selectSQL).Order("ro.id DESC").Offset((page - 1) * size).Limit(size).Scan(&items).Error; err != nil {
		return nil, err
	}
	return &DistributionOrderPage{Items: items, Total: total, Page: page, PageSize: size}, nil
}

func (r *Repository) FindOrder(ctx context.Context, id uint64) (*DistributionOrderDTO, error) {
	var item DistributionOrderDTO
	err := r.db.WithContext(ctx).Table("rental_orders ro").Joins("JOIN distribution_order_financials f ON f.order_id = ro.id").Select("ro.id AS order_id, ro.order_no, ro.distribution_site_id AS site_id, ro.listing_id, ro.account_id, ro.owner_id, ro.renter_id, ro.status, ro.handoff_status, ro.refund_status, ro.settlement_status, ro.distribution_mode, f.gross_paid_amount_cent, f.refund_amount_cent, f.net_paid_amount_cent, f.payment_fee_cent, f.service_fee_cent, f.markup_amount_cent, f.tax_amount_cent, f.split_base_amount_cent, ro.created_at").Where("ro.id = ?", id).Scan(&item).Error
	if err != nil {
		return nil, err
	}
	if item.OrderID == 0 {
		return nil, ErrOrderNotFound
	}
	return &item, nil
}

func (r *Repository) ListAccountDisplays(ctx context.Context, siteID uint64, status string) ([]AccountDisplayDTO, error) {
	var rows []model.DistributionSiteAccount
	db := r.db.WithContext(ctx).Where("site_id = ?", siteID).Order("id DESC")
	if status != "" {
		db = db.Where("display_status = ?", status)
	}
	if err := db.Find(&rows).Error; err != nil {
		return nil, err
	}
	items := make([]AccountDisplayDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, AccountDisplayDTO{ID: row.ID, SiteID: row.SiteID, AccountID: row.AccountID, ListingID: row.ListingID, DisplayStatus: row.DisplayStatus})
	}
	return items, nil
}

func (r *Repository) UpdateAccountDisplay(ctx context.Context, id uint64, status string) (*AccountDisplayDTO, error) {
	var row model.DistributionSiteAccount
	if err := r.db.WithContext(ctx).First(&row, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrAccountDisplayNotFound
		}
		return nil, err
	}
	row.DisplayStatus = strings.TrimSpace(status)
	if err := r.db.WithContext(ctx).Save(&row).Error; err != nil {
		return nil, err
	}
	item := &AccountDisplayDTO{ID: row.ID, SiteID: row.SiteID, AccountID: row.AccountID, ListingID: row.ListingID, DisplayStatus: row.DisplayStatus}
	return item, nil
}

func (r *Repository) ListPaymentChannels(ctx context.Context, siteID uint64) ([]PaymentChannelDTO, error) {
	var rows []model.DistributionSitePaymentChannel
	if err := r.db.WithContext(ctx).Where("site_id = ?", siteID).Order("priority ASC, id ASC").Find(&rows).Error; err != nil {
		return nil, err
	}
	items := make([]PaymentChannelDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, PaymentChannelDTO{ID: row.ID, SiteID: row.SiteID, ConfigID: row.ConfigID, Priority: row.Priority, Status: row.Status})
	}
	return items, nil
}

func (r *Repository) BindPaymentChannel(ctx context.Context, siteID uint64, req BindPaymentChannelRequest) (*PaymentChannelDTO, error) {
	row := model.DistributionSitePaymentChannel{SiteID: siteID, ConfigID: req.ConfigID, Priority: req.Priority, Status: "active"}
	if err := r.db.WithContext(ctx).Where("site_id = ? AND config_id = ?", siteID, req.ConfigID).FirstOrCreate(&row).Error; err != nil {
		return nil, err
	}
	return &PaymentChannelDTO{ID: row.ID, SiteID: row.SiteID, ConfigID: row.ConfigID, Priority: row.Priority, Status: row.Status}, nil
}

func (r *Repository) UnbindPaymentChannel(ctx context.Context, id uint64) error {
	result := r.db.WithContext(ctx).Delete(&model.DistributionSitePaymentChannel{}, id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return ErrPaymentChannelNotFound
	}
	return nil
}

func (r *Repository) ListSettlementBatches(ctx context.Context, siteID uint64) ([]SettlementBatchDTO, error) {
	var rows []model.DistributionSettlementBatch
	if err := r.db.WithContext(ctx).Where("site_id = ?", siteID).Order("id DESC").Find(&rows).Error; err != nil {
		return nil, err
	}
	items := make([]SettlementBatchDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, SettlementBatchDTO{ID: row.ID, SiteID: row.SiteID, BatchNo: row.BatchNo, PeriodStart: row.PeriodStart, PeriodEnd: row.PeriodEnd, TotalAmountCent: row.TotalAmountCent, Status: row.Status})
	}
	return items, nil
}

func (r *Repository) CreateSettlementBatch(ctx context.Context, adminID uint64, req CreateSettlementBatchRequest) (*SettlementBatchDTO, error) {
	if req.PeriodEnd.Before(req.PeriodStart) {
		return nil, ErrInvalidPeriod
	}
	row := model.DistributionSettlementBatch{SiteID: req.SiteID, BatchNo: "DS" + time.Now().Format("20060102150405.000000000"), PeriodStart: req.PeriodStart, PeriodEnd: req.PeriodEnd, Status: "draft", CreatedBy: &adminID}
	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
		return nil, err
	}
	return &SettlementBatchDTO{ID: row.ID, SiteID: row.SiteID, BatchNo: row.BatchNo, PeriodStart: row.PeriodStart, PeriodEnd: row.PeriodEnd, TotalAmountCent: row.TotalAmountCent, Status: row.Status}, nil
}

func (r *Repository) MarkSettlementBatch(ctx context.Context, id uint64) (*SettlementBatchDTO, error) {
	var row model.DistributionSettlementBatch
	if err := r.db.WithContext(ctx).First(&row, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrSettlementBatchNotFound
		}
		return nil, err
	}
	if row.Status == "settled" {
		return nil, ErrBatchAlreadySettled
	}
	now := time.Now()
	row.Status = "settled"
	row.SettledAt = &now
	if err := r.db.WithContext(ctx).Save(&row).Error; err != nil {
		return nil, err
	}
	return &SettlementBatchDTO{ID: row.ID, SiteID: row.SiteID, BatchNo: row.BatchNo, PeriodStart: row.PeriodStart, PeriodEnd: row.PeriodEnd, TotalAmountCent: row.TotalAmountCent, Status: row.Status}, nil
}

func (r *Repository) CreateFinancialSnapshot(ctx context.Context, orderID uint64, req CreateFinancialSnapshotRequest) (*DistributionOrderDTO, error) {
	var rule model.DistributionRuleVersion
	if err := r.db.WithContext(ctx).First(&rule, req.RuleVersionID).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrRuleNotFound
		}
		return nil, err
	}
	if req.SiteID == 0 || orderID == 0 {
		return nil, ErrInvalidAmount
	}
	partyInputs := make([]PartyProfitInput, 0, len(req.Parties))
	for _, party := range req.Parties {
		partyInputs = append(partyInputs, PartyProfitInput{PartyRole: party.PartyRole, IncomeAmountCent: party.IncomeAmountCent, CostAmountCent: party.CostAmountCent})
	}
	result, err := CalculateSettlement(Rule{ServiceFeeValue: rule.ServiceFeeValue, ServiceFeeUnit: rule.ServiceFeeUnit, PaymentFeeBPS: rule.PaymentFeeBPS, TaxEnabled: rule.TaxEnabled, TaxRateBPS: rule.TaxRateBPS}, SettlementInput{GrossPaidAmountCent: req.GrossPaidAmountCent, RefundAmountCent: req.RefundAmountCent, MarkupAmountCent: req.MarkupAmountCent, GrossProfitByParty: partyInputs})
	if err != nil {
		return nil, err
	}
	err = r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		financial := model.DistributionOrderFinancial{OrderID: orderID, SiteID: req.SiteID, RuleVersionID: req.RuleVersionID, GrossPaidAmountCent: result.GrossPaidAmountCent, RefundAmountCent: result.RefundAmountCent, NetPaidAmountCent: result.NetPaidAmountCent, PaymentFeeBPS: rule.PaymentFeeBPS, PaymentFeeCent: result.PaymentFeeCent, ServiceFeeValue: rule.ServiceFeeValue, ServiceFeeUnit: rule.ServiceFeeUnit, ServiceFeeCent: result.ServiceFeeCent, MarkupAmountCent: result.MarkupAmountCent, TaxEnabled: rule.TaxEnabled, TaxRateBPS: rule.TaxRateBPS, TaxAmountCent: result.TaxAmountCent, SplitBaseAmountCent: result.SplitBaseAmountCent, SettlementStatus: "pending"}
		if err := tx.Where("order_id = ?", orderID).Assign(financial).FirstOrCreate(&financial).Error; err != nil {
			return err
		}
		if err := tx.Where("order_id = ?", orderID).Delete(&model.DistributionOrderParty{}).Error; err != nil {
			return err
		}
		for idx, party := range req.Parties {
			tax := int64(0)
			if idx < len(result.TaxByParty) {
				tax = result.TaxByParty[idx].TaxAmountCent
			}
			profit := party.IncomeAmountCent - party.CostAmountCent
			row := model.DistributionOrderParty{OrderID: orderID, SiteID: req.SiteID, PartyRole: party.PartyRole, PartyType: party.PartyType, PartyID: party.PartyID, Ratio: party.Ratio, IncomeAmountCent: party.IncomeAmountCent, CostAmountCent: party.CostAmountCent, ProfitAmountCent: profit, TaxAmountCent: tax}
			if err := tx.Create(&row).Error; err != nil {
				return err
			}
		}
		return tx.Model(&model.RentalOrder{}).Where("id = ?", orderID).Updates(map[string]any{"distribution_site_id": req.SiteID, "distribution_rule_version_id": req.RuleVersionID}).Error
	})
	if err != nil {
		return nil, err
	}
	return r.FindOrder(ctx, orderID)
}