import { describe, expect, it } from 'vitest'
import {
  DEFAULT_LIMIT,
  MAX_LIMIT,
  decodeDefaultCursor,
  encodeDefaultCursor,
  nextCursorFromPage,
  parsePaginationParams,
} from '../pagination'

describe('parsePaginationParams', () => {
  it('returns defaults when no params present', () => {
    const url = new URL('https://example.com/v1/x')
    expect(parsePaginationParams(url)).toEqual({ limit: DEFAULT_LIMIT, cursor: null })
  })

  it('parses limit and clamps to MAX_LIMIT', () => {
    const url = new URL('https://example.com/v1/x?limit=999')
    expect(parsePaginationParams(url).limit).toBe(MAX_LIMIT)
  })

  it('floors limit to default for non-numeric input', () => {
    const url = new URL('https://example.com/v1/x?limit=abc')
    expect(parsePaginationParams(url).limit).toBe(DEFAULT_LIMIT)
  })

  it('treats limit=0 as invalid → DEFAULT_LIMIT', () => {
    const url = new URL('https://example.com/v1/x?limit=0')
    expect(parsePaginationParams(url).limit).toBe(DEFAULT_LIMIT)
  })

  it('returns the cursor verbatim when supplied', () => {
    const url = new URL('https://example.com/v1/x?cursor=abc123')
    expect(parsePaginationParams(url).cursor).toBe('abc123')
  })
})

describe('default cursor encode/decode', () => {
  it('round-trips a row', () => {
    const row = { id: '8fd5b1f4-1234-1234-1234-1234567890ab', created_at: '2026-05-12T16:00:00Z' }
    const cur = encodeDefaultCursor(row)
    expect(cur).not.toBeNull()
    expect(decodeDefaultCursor(cur)).toEqual({ ts: row.created_at, id: row.id })
  })

  it('returns null for null input', () => {
    expect(encodeDefaultCursor(null)).toBeNull()
  })

  it('returns null when decoding a malformed cursor', () => {
    expect(decodeDefaultCursor('not-base64-or-json')).toBeNull()
    expect(decodeDefaultCursor('')).toBeNull()
    expect(decodeDefaultCursor(null)).toBeNull()
  })

  it('returns null when decoding a JSON object missing fields', () => {
    const cursor = Buffer.from(JSON.stringify({ foo: 'bar' })).toString('base64url')
    expect(decodeDefaultCursor(cursor)).toBeNull()
  })
})

describe('nextCursorFromPage', () => {
  const ID_A = '11111111-1111-1111-1111-111111111111'
  const ID_B = '22222222-2222-2222-2222-222222222222'
  const ID_C = '33333333-3333-3333-3333-333333333333'
  const row = (id: string, ts: string) => ({ id, created_at: ts })

  it('returns null when the page is not full', () => {
    const rows = [
      row(ID_A, '2026-01-01T00:00:00Z'),
      row(ID_B, '2026-01-02T00:00:00Z'),
    ]
    expect(nextCursorFromPage(rows, 5)).toBeNull()
  })

  it('returns a cursor when there are more rows than the limit', () => {
    const rows = [
      row(ID_A, '2026-01-01T00:00:00Z'),
      row(ID_B, '2026-01-02T00:00:00Z'),
      row(ID_C, '2026-01-03T00:00:00Z'),
    ]
    const cursor = nextCursorFromPage(rows, 2)
    expect(cursor).not.toBeNull()
    expect(decodeDefaultCursor(cursor)).toEqual({ ts: '2026-01-03T00:00:00Z', id: ID_C })
  })
})

describe('decodeDefaultCursor: strict format validation', () => {
  const validId = '8fd5b1f4-1234-1234-1234-1234567890ab'
  const validTs = '2026-05-12T16:00:00Z'

  const cursorFor = (payload: object): string =>
    Buffer.from(JSON.stringify(payload)).toString('base64url')

  it('rejects a cursor whose ts is a date-only string', () => {
    const cur = cursorFor({ ts: '2026-05-12', id: validId })
    expect(decodeDefaultCursor(cur)).toBeNull()
  })

  it('rejects a cursor whose id is not a UUID', () => {
    const cur = cursorFor({ ts: validTs, id: 'not-a-uuid' })
    expect(decodeDefaultCursor(cur)).toBeNull()
  })

  it('rejects a cursor with a SQL-injection-shaped ts value', () => {
    const cur = cursorFor({ ts: "'); drop table api_keys; --", id: validId })
    expect(decodeDefaultCursor(cur)).toBeNull()
  })

  it('accepts a well-formed cursor', () => {
    const cur = cursorFor({ ts: validTs, id: validId })
    expect(decodeDefaultCursor(cur)).toEqual({ ts: validTs, id: validId })
  })

  it('accepts ts with timezone offset and fractional seconds', () => {
    const ts = '2026-05-12T16:00:00.123+02:00'
    const cur = cursorFor({ ts, id: validId })
    expect(decodeDefaultCursor(cur)).toEqual({ ts, id: validId })
  })
})