| 1 | /** The most suggestions shown at once. */ |
| 2 | export const MAX_SUGGESTIONS = 5; |
| 3 | |
| 4 | /** What could complete the `@…` before the caret: where it starts, and the handles that fit, best first. */ |
| 5 | export type MentionMatch = { start: number; options: string[] }; |
| 6 | |
| 7 | /** |
| 8 | * The `@…` being typed just before the caret and what could complete it: |
| 9 | * the `handles` given (such as `@acme/backend`) whose name, or a team's |
| 10 | * own part after the `/`, starts with what is typed. At most |
| 11 | * `MAX_SUGGESTIONS`; nothing once one is typed in full. Null when the |
| 12 | * caret is not in a mention or nothing fits. |
| 13 | */ |
| 14 | export function mentionSuggestions(text: string, caret: number, handles: readonly string[] = []): MentionMatch | null { |
| 15 | const match = /(?:^|[\s(])@([\w./-]{0,100})$/.exec(text.slice(0, caret)); |
| 16 | if (!match) return null; |
| 17 | const typed = match[1].toLowerCase(); |
| 18 | const start = caret - match[1].length - 1; |
| 19 | const names = [...new Set(handles.map((handle) => (handle.startsWith("@") ? handle : `@${handle}`)))]; |
| 20 | if (names.some((name) => name.slice(1).toLowerCase() === typed)) return null; |
| 21 | const whole: string[] = []; |
| 22 | const part: string[] = []; |
| 23 | for (const name of names) { |
| 24 | const bare = name.slice(1).toLowerCase(); |
| 25 | if (bare.startsWith(typed)) whole.push(name); |
| 26 | else if (typed && !typed.includes("/") && bare.split("/")[1]?.startsWith(typed)) part.push(name); |
| 27 | } |
| 28 | const options = [...whole, ...part].slice(0, MAX_SUGGESTIONS); |
| 29 | return options.length > 0 ? { start, options } : null; |
| 30 | } |