package repository

import (
	"context"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"

	"with_you/internal/model"
)

type PostRefRepository interface {
	BatchUpsert(ctx context.Context, sourcePostID string, targetPostIDs []string) error
	DeleteBySourcePostID(ctx context.Context, sourcePostID string) error
	GetSourcesByTargetPostID(ctx context.Context, targetPostID string, page, pageSize int) ([]model.PostReference, int64, error)
	GetTargetsBySourcePostID(ctx context.Context, sourcePostID string) ([]model.PostReference, error)
	MarkStatusByTargetPostID(ctx context.Context, targetPostID string, status model.PostReferenceStatus) error
	IncrementClickCount(ctx context.Context, sourcePostID, targetPostID string) error
}

type postRefRepository struct {
	db *gorm.DB
}

func NewPostRefRepository(db *gorm.DB) PostRefRepository {
	return &postRefRepository{db: db}
}

func (r *postRefRepository) BatchUpsert(ctx context.Context, sourcePostID string, targetPostIDs []string) error {
	if len(targetPostIDs) == 0 {
		return nil
	}
	refs := make([]model.PostReference, 0, len(targetPostIDs))
	for _, targetID := range targetPostIDs {
		refs = append(refs, model.PostReference{
			SourcePostID: sourcePostID,
			TargetPostID: targetID,
			Status:       model.PostRefActive,
		})
	}
	return r.db.WithContext(ctx).Clauses(clause.OnConflict{
		Columns:   []clause.Column{{Name: "source_post_id"}, {Name: "target_post_id"}},
		DoUpdates: clause.AssignmentColumns([]string{"status", "updated_at"}),
	}).Create(&refs).Error
}

func (r *postRefRepository) DeleteBySourcePostID(ctx context.Context, sourcePostID string) error {
	return r.db.WithContext(ctx).Where("source_post_id = ?", sourcePostID).Delete(&model.PostReference{}).Error
}

func (r *postRefRepository) GetSourcesByTargetPostID(ctx context.Context, targetPostID string, page, pageSize int) ([]model.PostReference, int64, error) {
	var refs []model.PostReference
	var total int64

	if err := r.db.WithContext(ctx).Model(&model.PostReference{}).
		Where("target_post_id = ? AND status = ?", targetPostID, model.PostRefActive).
		Count(&total).Error; err != nil {
		return nil, 0, err
	}

	offset := (page - 1) * pageSize
	if err := r.db.WithContext(ctx).
		Where("target_post_id = ? AND status = ?", targetPostID, model.PostRefActive).
		Preload("SourcePost").
		Preload("SourcePost.User").
		Order("created_at DESC").
		Offset(offset).Limit(pageSize).
		Find(&refs).Error; err != nil {
		return nil, 0, err
	}

	return refs, total, nil
}

func (r *postRefRepository) GetTargetsBySourcePostID(ctx context.Context, sourcePostID string) ([]model.PostReference, error) {
	var refs []model.PostReference
	if err := r.db.WithContext(ctx).
		Where("source_post_id = ?", sourcePostID).
		Preload("TargetPost").
		Preload("TargetPost.User").
		Find(&refs).Error; err != nil {
		return nil, err
	}
	return refs, nil
}

func (r *postRefRepository) MarkStatusByTargetPostID(ctx context.Context, targetPostID string, status model.PostReferenceStatus) error {
	return r.db.WithContext(ctx).Model(&model.PostReference{}).
		Where("target_post_id = ?", targetPostID).
		Update("status", status).Error
}

func (r *postRefRepository) IncrementClickCount(ctx context.Context, sourcePostID, targetPostID string) error {
	return r.db.WithContext(ctx).Model(&model.PostReference{}).
		Where("source_post_id = ? AND target_post_id = ?", sourcePostID, targetPostID).
		UpdateColumn("click_count", gorm.Expr("click_count + 1")).Error
}