-- name: AddTaskDependency :exec
INSERT INTO task_dependencies (task_id, blocks_task_id)
VALUES ($1, $2)
ON CONFLICT (task_id, blocks_task_id) DO NOTHING;

-- name: RemoveTaskDependency :exec
DELETE FROM task_dependencies
WHERE task_id = $1 AND blocks_task_id = $2;

-- name: ListTaskBlockers :many
SELECT t.* FROM tasks t
JOIN task_dependencies td ON td.blocks_task_id = t.id
WHERE td.task_id = $1 AND t.deleted_at IS NULL;

-- name: ListTasksBlockedBy :many
SELECT t.* FROM tasks t
JOIN task_dependencies td ON td.task_id = t.id
WHERE td.blocks_task_id = $1 AND t.deleted_at IS NULL;

-- name: CheckDirectCircularDependency :one
-- Direct cycle: blocks_task_id is blocked by task_id (would create A->B and B->A)
SELECT EXISTS(
  SELECT 1 FROM task_dependencies
  WHERE task_id = $2 AND blocks_task_id = $1
) AS has_circle;