package models

import (
	"time"

	"gorm.io/gorm"
)

// Attachment represents a file attached to an article.
//
// Lifecycle (plan A — upload-then-bind):
//   - On the article-create page the article does not exist yet, so ArticleID
//     is 0 and the row is temporarily owned by SessionToken (a random value
//     generated for the page session).
//   - When the article is saved, ArticleCreate binds pending rows by
//     SessionToken, setting their ArticleID and clearing the token.
//   - On the edit page uploads carry the real ArticleID directly.
//
// Disk deduplication: StoredName is the SHA-256 of the file content. Before
// writing, the handler checks whether a file with that name already exists on
// disk; if so it is reused (no rewrite). Deletion uses reference counting —
// the disk file is removed only when no Attachment rows reference it.
type Attachment struct {
	ID           uint           `gorm:"primarykey" json:"id"`
	ArticleID    uint           `gorm:"index" json:"article_id"`        // 0 while pending on the create page
	SessionToken string         `gorm:"size:64;index" json:"-"`        // temporary ownership token for the create page
	UploaderID   uint           `gorm:"index" json:"uploader_id"`
	Filename     string         `gorm:"size:255" json:"filename"`       // original filename
	StoredName   string         `gorm:"size:64;index" json:"stored_name"` // SHA-256 hex, the on-disk filename
	Ext          string         `gorm:"size:32" json:"ext"`
	MIME         string         `gorm:"size:128" json:"mime"`
	Size         int64          `gorm:"default:0" json:"size"`
	Category     string         `gorm:"size:32" json:"category"`        // image/document/archive/video/other
	CreatedAt    time.Time      `json:"created_at"`
	UpdatedAt    time.Time      `json:"updated_at"`
	DeletedAt    gorm.DeletedAt `gorm:"index" json:"deleted_at"`
}

// TableName overrides the default GORM table name.
func (Attachment) TableName() string {
	return "attachments"
}

// AttachmentCategoryImage reports whether this attachment is an image (used to
// decide markdown insertion form: ![]() vs []()).
func (a *Attachment) IsImage() bool {
	return a.Category == CategoryImage
}