test_that("a5_cell constructor", {
  cell <- a5_cell("0800000000000006")
  expect_s3_class(cell, "a5_cell")
  expect_s3_class(cell, "vctrs_rcrd")
  expect_true(is.raw(vctrs::field(cell, "b1")))
  expect_true(is.raw(vctrs::field(cell, "b8")))
})

test_that("a5_cell coercion with character", {
  cell <- a5_cell("0800000000000006")
  combined <- vctrs::vec_c(cell, "0800000000000016")
  expect_s3_class(combined, "a5_cell")
  expect_length(combined, 2L)
})

test_that("is_a5_cell works", {
  expect_true(is_a5_cell(a5_cell("0000000000000abc")))
  expect_false(is_a5_cell("0000000000000abc"))
})

test_that("a5_cell rejects hex strings not exactly 16 characters", {
  expect_error(a5_cell("12346"), "exactly 16 characters")
  expect_error(a5_cell("0800000000000006f"), "exactly 16 characters")
  expect_error(a5_cell(c("0800000000000006", "abc")), "exactly 16 characters")
  # NA and valid 16-char hex pass

  expect_length(a5_cell(c("0800000000000006", NA)), 2L)
  # vec_cast path also validates
  expect_error(vctrs::vec_cast("short", a5_cell()), "exactly 16 characters")
})

test_that("a5_is_valid validates", {
  result <- a5_is_valid(c("0800000000000006", "not_valid", NA))
  expect_equal(result[1], TRUE)
  expect_equal(result[2], FALSE)
  expect_true(is.na(result[3]))
})

test_that("a5_is_valid works with a5_cell input", {
  cell <- a5_cell("0800000000000006")
  expect_true(a5_is_valid(cell))
})

test_that("as_a5_cell passes through a5_cell unchanged", {
  cell <- a5_cell("0800000000000006")
  expect_identical(as_a5_cell(cell), cell)
})

test_that("as_a5_cell coerces character", {
  cell <- as_a5_cell("0800000000000006")
  expect_s3_class(cell, "a5_cell")
})

test_that("a5_cell handles NA values", {
  cell <- a5_cell(c("0800000000000006", NA))
  expect_length(cell, 2L)
  # NA is represented by the sentinel value (b8 == 0xFC)
  expect_true(is.na(cell[2]))
})

test_that("format.a5_cell preserves hex strings", {
  cell <- a5_cell(c("0800000000000006", NA))
  formatted <- format(cell)
  expect_equal(formatted[1], "0800000000000006")
  expect_true(is.na(formatted[2]))
})

test_that("a5_u64_to_hex works", {
  cell <- a5_cell("0800000000000006")
  expect_equal(a5_u64_to_hex(cell), "0800000000000006")
})

test_that("a5_hex_to_u64 works", {
  cell <- a5_hex_to_u64("0800000000000006")
  expect_s3_class(cell, "a5_cell")
  expect_equal(format(cell), "0800000000000006")
})

test_that("vec_cast round-trips a5_cell <-> character", {
  cell <- a5_cell("0800000000000006")
  chr <- vctrs::vec_cast(cell, character())
  expect_equal(chr, "0800000000000006")
  back <- vctrs::vec_cast(chr, a5_cell())
  expect_s3_class(back, "a5_cell")
  expect_equal(format(back), "0800000000000006")
})

test_that("vec_c combines a5_cell + a5_cell", {
  a <- a5_cell("0800000000000006")
  b <- a5_cell("0800000000000016")
  combined <- vctrs::vec_c(a, b)
  expect_s3_class(combined, "a5_cell")
  expect_length(combined, 2L)
  expect_equal(
    format(combined),
    c("0800000000000006", "0800000000000016")
  )
})

test_that("vec_c combines character + a5_cell (character first)", {
  cell <- a5_cell("0800000000000016")
  combined <- vctrs::vec_c("0800000000000006", cell)
  expect_s3_class(combined, "a5_cell")
  expect_length(combined, 2L)
})

test_that("vec_ptype_abbr and vec_ptype_full dispatch correctly", {
  cell <- a5_cell("0800000000000006")
  expect_equal(vec_ptype_abbr.a5_cell(cell), "a5_cell")
  expect_equal(vec_ptype_full.a5_cell(cell), "a5_cell")
})

test_that("pillar_shaft.a5_cell formats correctly", {
  skip_if_not_installed("pillar")
  cell <- a5_cell(c("0800000000000006", NA))
  shaft <- pillar_shaft.a5_cell(cell)
  expect_s3_class(shaft, "pillar_shaft")
})

test_that("a5_cell displays correctly in tibbles", {
  skip_if_not_installed("tibble")
  skip_if_not_installed("pillar")
  tbl <- tibble::tibble(
    cell = a5_cell(c("0800000000000006", "0800000000000016"))
  )

  testthat::expect_snapshot(tbl)

  out <- format(tbl)
  expect_true(any(grepl("a5_cell", out)))
  expect_true(any(grepl("0800000000000006", out)))
})

test_that("str works on a5_cell", {
  cell <- a5_cell(c("0800000000000006", "0800000000000016"))
  out <- capture.output(str(cell))
  expect_true(any(grepl("a5_cell", out)))
})

test_that("wk_crs.a5_cell returns longlat CRS", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 5)
  expect_identical(wk::wk_crs(cell), wk::wk_crs_longlat())
})

test_that("wk_handle.a5_cell produces boundary geometry", {
  cell <- a5_lonlat_to_cell(0, 0, resolution = 5)
  wkt <- wk::wk_handle(cell, wk::wkt_writer())
  expect_s3_class(wkt, "wk_wkt")
  expect_true(grepl("^POLYGON", as.character(wkt)))
})

# -- sentinel / NA byte-level tests -------------------------------------------

test_that("NA sentinel has b8 == 0xFC", {
  cell <- a5_cell(c("0800000000000006", NA))
  # Non-NA cell: b8 should NOT be 0xFC
  expect_false(vctrs::field(cell, "b8")[1] == as.raw(0xFC))
  # NA cell: b8 IS the sentinel byte

  expect_equal(vctrs::field(cell, "b8")[2], as.raw(0xFC))
})

test_that("sentinel hex value fc00000000000000 becomes NA", {
  cell <- a5_cell("fc00000000000000")
  expect_true(is.na(cell))
  expect_true(is.na(format(cell)))
})

test_that("known hex encodes to correct little-endian bytes", {
  cell <- a5_cell("0800000000000006")
  # 0x0800000000000006 in little-endian: 06 00 00 00 00 00 00 08
  expect_equal(vctrs::field(cell, "b1"), as.raw(0x06))
  expect_equal(vctrs::field(cell, "b2"), as.raw(0x00))
  expect_equal(vctrs::field(cell, "b7"), as.raw(0x00))
  expect_equal(vctrs::field(cell, "b8"), as.raw(0x08))
})

# -- empty / all-NA edge cases ------------------------------------------------

test_that("empty a5_cell works", {
  cell <- a5_cell(character())
  expect_length(cell, 0L)
  expect_s3_class(cell, "a5_cell")
  expect_equal(format(cell), character())
})

test_that("all-NA a5_cell works", {
  cell <- a5_cell(c(NA, NA, NA))
  expect_length(cell, 3L)
  expect_true(all(is.na(cell)))
})

test_that("single NA a5_cell works", {
  cell <- a5_cell(NA)
  expect_length(cell, 1L)
  expect_true(is.na(cell))
})

# -- vctrs operations: unique, duplicated, match ------------------------------

test_that("unique works on a5_cell", {
  cells <- a5_cell(c(
    "0800000000000006",
    "0800000000000016",
    "0800000000000006"
  ))
  u <- unique(cells)
  expect_length(u, 2L)
  expect_equal(sort(format(u)), c("0800000000000006", "0800000000000016"))
})

test_that("duplicated works on a5_cell", {
  cells <- a5_cell(c(
    "0800000000000006",
    "0800000000000016",
    "0800000000000006"
  ))
  expect_equal(duplicated(cells), c(FALSE, FALSE, TRUE))
})

test_that("match works on a5_cell", {
  haystack <- a5_cell(c("0800000000000006", "0800000000000016"))
  needle <- a5_cell("0800000000000016")
  expect_equal(match(needle, haystack), 2L)
})

test_that("%in% works on a5_cell", {
  cells <- a5_cell(c(
    "0800000000000006",
    "0800000000000016",
    "0800000000000026"
  ))
  subset <- a5_cell(c("0800000000000006", "0800000000000026"))
  expect_equal(cells %in% subset, c(TRUE, FALSE, TRUE))
})

test_that("unique handles NA correctly", {
  cells <- a5_cell(c("0800000000000006", NA, NA))
  u <- unique(cells)
  expect_length(u, 2L)
  expect_equal(sum(is.na(u)), 1L)
})

# -- ordering -----------------------------------------------------------------

test_that("sort orders by u64 value", {
  # Create cells with known ordering: lower hex = lower u64
  cells <- a5_cell(c(
    "0800000000000016",
    "0800000000000006",
    "0800000000000026"
  ))
  sorted <- sort(cells)
  expect_equal(
    format(sorted),
    c("0800000000000006", "0800000000000016", "0800000000000026")
  )
})

test_that("sort handles NA (pushed to end)", {
  cells <- a5_cell(c(NA, "0800000000000016", "0800000000000006"))
  sorted <- sort(cells, na.last = TRUE)
  expect_equal(format(sorted)[1:2], c("0800000000000006", "0800000000000016"))
  expect_true(is.na(sorted[3]))
})

test_that("order returns correct indices", {
  cells <- a5_cell(c(
    "0800000000000016",
    "0800000000000006",
    "0800000000000026"
  ))
  expect_equal(order(cells), c(2L, 1L, 3L))
})

test_that("comparison operators work", {
  a <- a5_cell("0800000000000006")
  b <- a5_cell("0800000000000016")
  expect_true(a < b)
  expect_false(a > b)
  expect_true(a == a)
  expect_true(a != b)
})

# -- memory -------------------------------------------------------------------

test_that("a5_cell memory is compact (8 raw vectors)", {
  cells <- a5_lonlat_to_cell(runif(1000, -180, 180), runif(1000, -80, 80), 10L)
  # Should be ~8 KB (8 x 1 byte x 1000), not ~56 KB+ from list-of-raw
  sz <- as.numeric(object.size(cells))
  expect_true(sz < 50000) # well under list-of-raw overhead
})