import { describe, expect, it } from 'vitest'

import {
  isUuidLike,
  resolveParticipantDisplayName,
} from './resolveParticipantDisplayName'

describe('isUuidLike', () => {
  it('returns true for standard UUID strings', () => {
    expect(isUuidLike('a1b2c3d4-e5f6-4789-a012-3456789abcde')).toBe(true)
  })

  it('returns false for regular display names', () => {
    expect(isUuidLike('Alice')).toBe(false)
  })
})

describe('resolveParticipantDisplayName', () => {
  it('returns a valid name when present', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'user-1',
        name: 'Alice',
        username: 'alice',
      })
    ).toBe('Alice')
  })

  it('prefers username when name is missing', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'user-1',
        username: 'alice',
      })
    ).toBe('alice')
  })

  it('prefers username when name is UUID-like', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'user-1',
        name: 'a1b2c3d4-e5f6-4789-a012-3456789abcde',
        username: 'alice',
      })
    ).toBe('alice')
  })

  it('never falls back to user id', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'opaque-user-id',
        name: 'opaque-user-id',
      })
    ).toBe('Unknown member')
  })

  it('treats the `Follower <id>` placeholder name as missing', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'opaque-user-id',
        name: 'Follower opaque-user-id',
      })
    ).toBe('Unknown member')
  })

  it('falls back to username when the name is the `Follower <id>` placeholder', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'opaque-user-id',
        name: 'Follower opaque-user-id',
        username: 'alice',
      })
    ).toBe('alice')
  })

  it('does not treat a real name beginning with "Follower" as the placeholder', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'opaque-user-id',
        name: 'Follower of Jesus',
      })
    ).toBe('Follower of Jesus')
  })

  it('returns Unknown member when no usable fields exist', () => {
    expect(resolveParticipantDisplayName({ id: 'user-1' })).toBe(
      'Unknown member'
    )
    expect(resolveParticipantDisplayName(undefined)).toBe('Unknown member')
  })

  it('ignores whitespace-only values', () => {
    expect(
      resolveParticipantDisplayName({
        id: 'user-1',
        name: '   ',
        username: 'alice',
      })
    ).toBe('alice')
  })
})