// Package pendingattach holds the canonical pending-attachment row type
// and its dedupe helper. It imports nothing from the rest of mort so
// every consumer (the skills storage layer, the send_attachments tool,
// and all delivery drainers) can depend on it without import cycles.
//
// CONTRACT: enqueue (Storage.AddPendingAttachment) is NOT idempotent — a
// model that calls send_attachments more than once for the same file
// leaves multiple rows. Every consumer that drains pending attachments
// MUST call Dedupe before delivery, or the artifact double-posts.
package pendingattach

import "time"

// Attachment is one deferred-attachment row. Field-for-field the shape
// the skills storage layer persists.
type Attachment struct {
	ID          string
	RunID       string
	SkillID     string
	FileID      string
	Filename    string
	Mime        string
	SizeBytes   int64
	MessageText string
	HostedURL   string
	Ord         int

	// CreatedAt is the enqueue time. Used only by the retention sweeper
	// (PurgePendingAttachments) and storage round-trip tests; delivery
	// drainers ignore it. Zero on the enqueue path — the storage layer
	// defaults it to time.Now().
	CreatedAt time.Time
}

// Dedupe removes rows whose FileID has already been seen (first
// occurrence wins, preserving input order). Rows with an empty FileID
// are never collapsed.
func Dedupe(rows []Attachment) []Attachment {
	if len(rows) < 2 {
		return rows
	}
	seen := make(map[string]struct{}, len(rows))
	out := make([]Attachment, 0, len(rows))
	for _, row := range rows {
		if row.FileID != "" {
			if _, dup := seen[row.FileID]; dup {
				continue
			}
			seen[row.FileID] = struct{}{}
		}
		out = append(out, row)
	}
	return out
}