import gleam/list
import gleeunit
import gleeunit/should
import kmer.{type DecodeResult, type DecodedValue, Integer}

pub fn main() {
  gleeunit.main()
}

fn table_test_decode_next_value(test_case: BitArray, expected: DecodedValue) {
  kmer.decode_next_value(test_case) |> is_value(expected)
}

fn is_value(val: DecodeResult, expected: DecodedValue) {
  should.be_ok(val) |> should.equal(#(expected, <<>>))
}

pub fn decode_immediate_int_test() {
  [
    // Small integers under 24
    #(<<0>>, Integer(0)),
    #(<<10>>, Integer(10)),
    #(<<23>>, Integer(23)),
  ]
  |> table_fn(table_test_decode_next_value)
}

pub fn decode_int_test() {
  [
    // 1-byte length (Maj.arg 24)
    #(<<24, 24>>, Integer(24)),
    #(<<24, 100>>, Integer(100)),
    // 2-byte length (Maj.arg 25)
    #(<<25, 1234:16>>, Integer(1234)),
    #(<<25, 12_345:16>>, Integer(12_345)),
    // 3-byte length (Maj.arg 26)
    #(<<26, 1_234_567:32>>, Integer(1_234_567)),
    #(<<26, 999_999_999:32>>, Integer(999_999_999)),
    // 4-byte length (Maj.arg 27)
    #(<<27, 2_099_210_021_019_898_881:64>>, Integer(2_099_210_021_019_898_881)),
    #(<<27, 3:64>>, Integer(3)),
  ]
  |> table_fn(table_test_decode_next_value)
}

pub fn decode_negative_int_test() {
  [
    // Immediate negative (under 25)
    #(<<1:3, 0:5>>, Integer(-1)),
    #(<<1:3, 8:5>>, Integer(-9)),
    #(<<1:3, 23:5>>, Integer(-24)),
    // 1-byte length (Maj.arg 24)
    #(<<1:3, 24:5, 24:8>>, Integer(-25)),
    #(<<1:3, 24:5, 100:8>>, Integer(-101)),
    // 2-byte length (Maj.arg 25)
    #(<<1:3, 25:5, 1234:16>>, Integer(-1235)),
    #(<<1:3, 25:5, 12_345:16>>, Integer(-12_346)),
    // 3-byte length (Maj.arg 26)
    #(<<1:3, 26:5, 1_234_567:32>>, Integer(-1_234_568)),
    #(<<1:3, 26:5, 999_999_999:32>>, Integer(-1_000_000_000)),
    // 4-byte length (Maj.arg 27)
    #(
      <<1:3, 27:5, 2_099_210_021_019_898_881:64>>,
      Integer(-2_099_210_021_019_898_882),
    ),
    #(<<1:3, 27:5, 3:64>>, Integer(-4)),
  ]
  |> table_fn(table_test_decode_next_value)
}

fn table_fn(tests: List(#(a, b)), test_fn: fn(a, b) -> Nil) {
  list.map(tests, fn(t) {
    let #(test_case, expected) = t
    test_fn(test_case, expected)
  })
}