-module(etui@braille).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/etui/braille.gleam").
-export([new/0, set_pixel/5, bit/2, put/4, flush/4]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

-file("src/etui/braille.gleam", 20).
?DOC(" Empty pixel grid.\n").
-spec new() -> gleam@dict:dict({integer(), integer()}, {integer(),
    etui@style:color()}).
new() ->
    maps:new().

-file("src/etui/braille.gleam", 26).
?DOC(
    " Set a pixel at terminal-cell (char_x, char_y), accumulating its bit into\n"
    " the existing mask. Color overrides any prior color for that cell.\n"
).
-spec set_pixel(
    gleam@dict:dict({integer(), integer()}, {integer(), etui@style:color()}),
    integer(),
    integer(),
    integer(),
    etui@style:color()
) -> gleam@dict:dict({integer(), integer()}, {integer(), etui@style:color()}).
set_pixel(Pixels, Char_x, Char_y, Bit, Fg) ->
    Key = {Char_x, Char_y},
    Existing = case gleam_stdlib:map_get(Pixels, Key) of
        {ok, {M, _}} ->
            M;

        {error, _} ->
            0
    end,
    gleam@dict:insert(Pixels, Key, {erlang:'bor'(Existing, Bit), Fg}).

-file("src/etui/braille.gleam", 48).
?DOC(
    " Bitmask bit for the dot at (col, row) inside a 2×4 braille cell.\n"
    " Layout (Unicode braille dot numbering):\n"
    "   col 0  col 1\n"
    "   row 0    1     8\n"
    "   row 1    2    16\n"
    "   row 2    4    32\n"
    "   row 3   64   128\n"
).
-spec bit(integer(), integer()) -> integer().
bit(Col, Row) ->
    case {Col, Row} of
        {0, 0} ->
            1;

        {0, 1} ->
            2;

        {0, 2} ->
            4;

        {0, 3} ->
            64;

        {1, 0} ->
            8;

        {1, 1} ->
            16;

        {1, 2} ->
            32;

        {1, 3} ->
            128;

        {_, _} ->
            0
    end.

-file("src/etui/braille.gleam", 64).
?DOC(
    " Write a single pixel at absolute braille-pixel coords (px, py) into the\n"
    " pixel grid. Out-of-bounds coords (px < 0 or py < 0) are dropped.\n"
).
-spec put(
    gleam@dict:dict({integer(), integer()}, {integer(), etui@style:color()}),
    integer(),
    integer(),
    etui@style:color()
) -> gleam@dict:dict({integer(), integer()}, {integer(), etui@style:color()}).
put(Pixels, Px, Py, Fg) ->
    case (Px < 0) orelse (Py < 0) of
        true ->
            Pixels;

        false ->
            set_pixel(Pixels, Px div 2, Py div 4, bit(Px rem 2, Py rem 4), Fg)
    end.

-file("src/etui/braille.gleam", 73).
?DOC(
    " Flush the pixel grid into a buffer at the given area's origin.\n"
    " Each populated cell becomes one braille glyph.\n"
).
-spec flush(
    etui@buffer:buffer(),
    etui@geometry:rect(),
    gleam@dict:dict({integer(), integer()}, {integer(), etui@style:color()}),
    etui@style:color()
) -> etui@buffer:buffer().
flush(Buf, Area, Pixels, Bg) ->
    gleam@dict:fold(
        Pixels,
        Buf,
        fun(B, Key, Val) ->
            {Char_x, Char_y} = Key,
            {Mask, Fg} = Val,
            Ch = case gleam@string:utf_codepoint(16#2800 + Mask) of
                {ok, Cp} ->
                    gleam_stdlib:utf_codepoint_list_to_string([Cp]);

                {error, _} ->
                    <<"·"/utf8>>
            end,
            etui@buffer:set_string(
                B,
                {position,
                    erlang:element(2, erlang:element(2, Area)) + Char_x,
                    erlang:element(3, erlang:element(2, Area)) + Char_y},
                Ch,
                Fg,
                Bg,
                etui@style:none()
            )
        end
    ).