open Year2024.Day04.Part01

let example_input =
  [ "MMMSXXMASM"
  ; "MSAMXMSMSA"
  ; "AMXSXMAAMM"
  ; "MSAMASMSMX"
  ; "XMASAMXAMM"
  ; "XXAMMXXAMA"
  ; "SMSMSASXSS"
  ; "SAXAMASAAA"
  ; "MAMMMXMMMM"
  ; "MXMXAXMASX" ]

let is_in_bounds_tests =
  let test_is_in_bounds expected length index _ =
    let actual = is_in_bounds length index in
    assert_equal ~printer:string_of_bool expected actual
  in
  [ "not in bounds if below 0" >:: test_is_in_bounds false 1 (-1)
  ; "in bounds if gte 0 and lt length" >:: test_is_in_bounds true 1 0
  ; "not in bounds if eq length" >:: test_is_in_bounds false 1 1
  ; "not in bounds if gt length" >:: test_is_in_bounds false 1 2 ]

let calculate_num_of_matches_tests =
  let test_calculate_num_of_matches expected line row_offset character _ =
    let actual = calculate_num_of_matches line row_offset character in
    assert_equal ~printer:string_of_int expected actual
  in
  [ "is 0 when no matches present"
    >:: test_calculate_num_of_matches 0 "SMMX" 1 {index= 3; character= 'X'}
  ; "is 1 when only one match present - top to bottom"
    >::
    (*
      |.|X|.|
      |.|M|.|
      |.|A|.|
      |.|S|.|
    *)
    test_calculate_num_of_matches 1 ".X..M..A..S." 3 {index= 1; character= 'X'}
  ; "is 1 when only one match present - top to bottom edge"
    >::
    (*
      |X|.|.|
      |M|.|.|
      |A|.|.|
      |S|.|.|
    *)
    test_calculate_num_of_matches 1 "X..M..A..S.." 3 {index= 0; character= 'X'}
  ; "is 1 when only one match present - bottom to top"
    >::
    (*
      |.|S|.|
      |.|A|.|
      |.|M|.|
      |.|X|.|
    *)
    test_calculate_num_of_matches 1 ".S..A..M..X." 3 {index= 10; character= 'X'}
  ; "is 1 when only one match present - left to right"
    >::
    (*
      |X|M|A|S|
    *)
    test_calculate_num_of_matches 1 "XMAS" 4 {index= 0; character= 'X'}
  ; "is 1 when only one match present - right to left"
    >::
    (*
      |S|A|M|X|
    *)
    test_calculate_num_of_matches 1 "SAMX" 4 {index= 3; character= 'X'}
  ; "is 1 when only one match present - bottom right to top left"
    >::
    (*
      |S|.|.|.|
      |.|A|.|.|
      |.|.|M|.|
      |.|.|.|X|
    *)
    test_calculate_num_of_matches 1 "S....A....M....X" 4
      {index= 15; character= 'X'}
  ; "is 1 when only one match present - top left to bottom right"
    >::
    (*
      |X|.|.|.|
      |.|M|.|.|
      |.|.|A|.|
      |.|.|.|S|
    *)
    test_calculate_num_of_matches 1 "X....M....A....S" 4
      {index= 0; character= 'X'}
  ; "is 1 when only one match present - bottom left to top right"
    >::
    (*
      |.|.|.|S|
      |.|.|A|.|
      |.|M|.|.|
      |X|.|.|.|
    *)
    test_calculate_num_of_matches 1 "...S..A..M..X..." 4
      {index= 12; character= 'X'}
  ; "is 1 when only one match present - top right to bottom left"
    >::
    (*
      |.|.|.|X|
      |.|.|M|.|
      |.|A|.|.|
      |S|.|.|.|
    *)
    test_calculate_num_of_matches 1 "...X..M..A..S..." 4
      {index= 3; character= 'X'}
  ; "is 8 when matches present in all possible directions"
    >::
    (*
            |S|.|.|S|.|.|S|
            |.|A|.|A|.|A|.|
            |.|.|M|M|M|.|.|
            |S|A|M|X|M|A|S|
            |.|.|M|M|M|.|.|
            |.|A|.|A|.|A|.|
            |S|.|.|S|.|.|S|
    *)
    test_calculate_num_of_matches 8
      "S..S..S.A.A.A...MMM..SAMXMAS..MMM...A.A.A.S..S..S" 7
      {index= 24; character= 'X'} ]

let solve_tests =
  let test_solve have want () =
    let actual = solve have in
    Alcotest.(check int) "incorrect solution" want actual
  in
  [ ( "test solution"
    , [ Alcotest.test_case "example is solved correctly" `Quick
        @@ test_solve example_input 18
      ; Alcotest.test_case "minimal example is solved correctly" `Quick
        @@ test_solve ["..X..."; ".SAMX."; ".A..A."; "XMAS.S"; ".X...."] 4 ] )
  ]

let () =
  let open Alcotest in
  run "test suite for day 4 part 1" is_in_bounds_tests
  @ calculate_num_of_matches_tests @ solve_tests