store: add list_items, the fourth append-only shape (V-453)

A list is a standing set of short strings under a tag. Not a task, because
milk is not work and the prioritiser must not count it as an errand; not a
fact, because it claims nothing. Nothing predicates over it, so two people
adding to the same list at once costs nothing.

Migration #19, plus AddListItem, ListItems, SetListItemStatus and ClearList.
The live-only unique index is the tasks one, per list: молоко twice before
the shop is one row, молоко again after it was crossed off is a new one.

internal/store/listitems.go

@@ -0,0 +1,194 @@
+package store
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+)
+
+// List items — the fourth append-only shape (Vikunja #453).
+//
+// A list is a standing set of short strings under a tag: покупки, аптека,
+// хозяйство. It is not work and it is not a claim about the world, which is
+// why it is neither a task nor a fact. Nothing here is prioritised, nothing
+// nudges about it, and the digestion worker does not read it. The only two
+// things a list does are grow and shrink.
+//
+// The consequence that made it worth a table: because no predicate touches a
+// list item, several people adding to the same list at once cost nothing. There
+// is no ranking to disagree about and no lifecycle beyond crossed-off.
+const (
+	// ListItemOpen — on the list.
+	ListItemOpen = "open"
+	// ListItemDone — bought, taken, crossed off.
+	ListItemDone = "done"
+	// ListItemDropped — removed without being got.
+	ListItemDropped = "dropped"
+)
+
+// DefaultList — the list a capture lands on when he names none. Almost every
+// spoken list item is groceries, and asking "в какой список?" for the common
+// case would be a nag.
+const DefaultList = "покупки"
+
+// ListItem — one line on one list.
+type ListItem struct {
+	ID         int64
+	CreatedTs  time.Time
+	List       string
+	Item       string
+	Source     string
+	Status     string
+	ResolvedTs *time.Time
+}
+
+var (
+	ErrListItemNotFound = errors.New("store: list item not found")
+	ErrListItemEmpty    = errors.New("store: list item is empty")
+	ErrListItemStatus   = errors.New("store: invalid list item status")
+)
+
+// NormalizeListName folds a list tag to its dedupe form. Lists are named out
+// loud, so "Покупки" and "покупки " are the same list.
+func NormalizeListName(s string) string {
+	n := NormalizeTaskText(s)
+	if n == "" {
+		return DefaultList
+	}
+	return n
+}
+
+// AddListItem puts an item on a list, or returns the existing row when the same
+// item is already on it. Created says which happened, so the caller can say
+// "уже есть" instead of pretending it wrote something.
+func (s *Store) AddListItem(ctx context.Context, li ListItem) (CaptureResult, error) {
+	item := strings.TrimSpace(li.Item)
+	if item == "" {
+		return CaptureResult{}, ErrListItemEmpty
+	}
+	list := NormalizeListName(li.List)
+	norm := NormalizeTaskText(item)
+	created := li.CreatedTs
+	if created.IsZero() {
+		created = time.Now()
+	}
+	res, err := s.db.ExecContext(ctx,
+		`INSERT INTO list_items (created_ts, list, item, norm, source, status)
+		 VALUES (?,?,?,?,?,?)
+		 ON CONFLICT DO NOTHING`,
+		created.UnixMilli(), list, item, norm, li.Source, ListItemOpen)
+	if err != nil {
+		return CaptureResult{}, fmt.Errorf("add list item: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return CaptureResult{}, fmt.Errorf("add list item: rows affected: %w", err)
+	}
+	if n > 0 {
+		id, err := res.LastInsertId()
+		if err != nil {
+			return CaptureResult{}, fmt.Errorf("add list item: last insert id: %w", err)
+		}
+		return CaptureResult{ID: id, Created: true}, nil
+	}
+	var id int64
+	err = s.db.QueryRowContext(ctx,
+		`SELECT id FROM list_items WHERE list = ? AND norm = ? AND status = ?`,
+		list, norm, ListItemOpen).Scan(&id)
+	if errors.Is(err, sql.ErrNoRows) {
+		return CaptureResult{}, ErrListItemNotFound
+	}
+	if err != nil {
+		return CaptureResult{}, fmt.Errorf("add list item: lookup: %w", err)
+	}
+	return CaptureResult{ID: id}, nil
+}
+
+// ListItems reads one list in the order it was added. An empty status reads the
+// open items, which is what reading the list aloud means.
+func (s *Store) ListItems(ctx context.Context, list, status string) ([]ListItem, error) {
+	if status == "" {
+		status = ListItemOpen
+	}
+	rows, err := s.db.QueryContext(ctx,
+		`SELECT id, created_ts, list, item, source, status, resolved_ts
+		   FROM list_items WHERE list = ? AND status = ?
+		  ORDER BY created_ts, id`,
+		NormalizeListName(list), status)
+	if err != nil {
+		return nil, fmt.Errorf("list items: %w", err)
+	}
+	defer rows.Close()
+	var out []ListItem
+	for rows.Next() {
+		var (
+			li       ListItem
+			created  int64
+			resolved sql.NullInt64
+		)
+		if err := rows.Scan(&li.ID, &created, &li.List, &li.Item, &li.Source, &li.Status, &resolved); err != nil {
+			return nil, fmt.Errorf("list items: scan: %w", err)
+		}
+		li.CreatedTs = time.UnixMilli(created)
+		if resolved.Valid {
+			t := time.UnixMilli(resolved.Int64)
+			li.ResolvedTs = &t
+		}
+		out = append(out, li)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("list items: %w", err)
+	}
+	return out, nil
+}
+
+// SetListItemStatus crosses an item off, or removes it. Moving an item that is
+// already resolved is not an error — crossing off twice is the same list.
+func (s *Store) SetListItemStatus(ctx context.Context, id int64, status string, at time.Time) error {
+	if status != ListItemOpen && status != ListItemDone && status != ListItemDropped {
+		return fmt.Errorf("%w: %q", ErrListItemStatus, status)
+	}
+	var resolved sql.NullInt64
+	if status != ListItemOpen {
+		if at.IsZero() {
+			at = time.Now()
+		}
+		resolved = sql.NullInt64{Int64: at.UnixMilli(), Valid: true}
+	}
+	res, err := s.db.ExecContext(ctx,
+		`UPDATE list_items SET status = ?, resolved_ts = ? WHERE id = ?`,
+		status, resolved, id)
+	if err != nil {
+		return fmt.Errorf("set list item status: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("set list item status: rows affected: %w", err)
+	}
+	if n == 0 {
+		return ErrListItemNotFound
+	}
+	return nil
+}
+
+// ClearList crosses off every open item on a list and reports how many. This is
+// "всё купил", which is one sentence and must not become one turn per item.
+func (s *Store) ClearList(ctx context.Context, list string, at time.Time) (int, error) {
+	if at.IsZero() {
+		at = time.Now()
+	}
+	res, err := s.db.ExecContext(ctx,
+		`UPDATE list_items SET status = ?, resolved_ts = ? WHERE list = ? AND status = ?`,
+		ListItemDone, at.UnixMilli(), NormalizeListName(list), ListItemOpen)
+	if err != nil {
+		return 0, fmt.Errorf("clear list: %w", err)
+	}
+	n, err := res.RowsAffected()
+	if err != nil {
+		return 0, fmt.Errorf("clear list: rows affected: %w", err)
+	}
+	return int(n), nil
+}

internal/store/migrations.go

@@ -219,6 +219,27 @@ ALTER TABLE reminders ADD COLUMN next_fire_ts INTEGER;`, // #2
 	// event, and the old rows would otherwise be recited as extra meetings.
 	// The filter is exact — it keeps any key whose summary part still has a
 	// letter or a digit in it.
+	`CREATE TABLE IF NOT EXISTS list_items (
+		id          INTEGER PRIMARY KEY AUTOINCREMENT,
+		created_ts  INTEGER NOT NULL,
+		list        TEXT    NOT NULL,
+		item        TEXT    NOT NULL,
+		norm        TEXT    NOT NULL,
+		source      TEXT    NOT NULL,
+		status      TEXT    NOT NULL DEFAULT 'open' CHECK (status IN ('open','done','dropped')),
+		resolved_ts INTEGER
+	);
+	CREATE UNIQUE INDEX IF NOT EXISTS idx_list_items_live ON list_items (list, norm) WHERE status = 'open';
+	CREATE INDEX IF NOT EXISTS idx_list_items_list ON list_items (list, status, created_ts);`,
+	// #19 — standing lists (Vikunja #453). The fourth append-only shape, after
+	// facts, notes and tasks, and the reason it is its own table rather than a
+	// tag on tasks: milk on the shopping list is not work. Nothing prioritises
+	// it, nothing nudges about it, and the prioritiser must not start counting
+	// groceries as outstanding errands.
+	//
+	// The live-only unique index is the tasks one, per list: saying "молоко"
+	// twice before the shop keeps one row, saying it again next week after the
+	// last one was crossed off writes a new one.
 }
 
 // migrate applies every migration with a number greater than the DB's current