sprocket

-module(sprocket@internal@patch).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function]).

-export([op_code/2, patch_to_json/2, create/2]).
-export_type([patch/0]).

-type patch() :: no_op |
    {update,
        gleam@option:option(list(sprocket@render:rendered_attribute())),
        gleam@option:option(list({integer(), patch()}))} |
    {replace, sprocket@render:rendered_element()} |
    {insert, sprocket@render:rendered_element()} |
    remove |
    {change, binary()} |
    {move, integer(), patch()}.

-spec attr_key(sprocket@render:rendered_attribute()) -> binary().
attr_key(Attribute) ->
    case Attribute of
        {rendered_attribute, Name, _} ->
            Name;

        {rendered_event_handler, _, Id} ->
            Id;

        {rendered_client_hook, _, Id@1} ->
            Id@1
    end.

-spec compare_attributes_helper(
    gleam@map:map_(binary(), sprocket@render:rendered_attribute()),
    list(sprocket@render:rendered_attribute())
) -> gleam@option:option(list(sprocket@render:rendered_attribute())).
compare_attributes_helper(Old_attributes, New_attributes) ->
    case New_attributes of
        [New_attr | Rest_new] ->
            case gleam@map:get(Old_attributes, attr_key(New_attr)) of
                {ok, Old_attr} ->
                    case Old_attr =:= New_attr of
                        true ->
                            case compare_attributes_helper(
                                gleam@map:delete(
                                    Old_attributes,
                                    attr_key(Old_attr)
                                ),
                                Rest_new
                            ) of
                                {some, _} ->
                                    {some, New_attributes};

                                none ->
                                    none
                            end;

                        false ->
                            {some, New_attributes}
                    end;

                _ ->
                    {some, New_attributes}
            end;

        _ ->
            case {gleam@map:size(Old_attributes),
                gleam@list:length(New_attributes)} of
                {0, 0} ->
                    none;

                {Old_size, New_size} when Old_size > New_size ->
                    {some, New_attributes}
            end
    end.

-spec build_attrs_map(list(sprocket@render:rendered_attribute())) -> gleam@map:map_(binary(), sprocket@render:rendered_attribute()).
build_attrs_map(Attributes) ->
    _pipe = Attributes,
    gleam@list:fold(
        _pipe,
        gleam@map:new(),
        fun(Acc, Attr) -> gleam@map:insert(Acc, attr_key(Attr), Attr) end
    ).

-spec compare_attributes(
    list(sprocket@render:rendered_attribute()),
    list(sprocket@render:rendered_attribute())
) -> gleam@option:option(list(sprocket@render:rendered_attribute())).
compare_attributes(Old_attributes, New_attributes) ->
    compare_attributes_helper(build_attrs_map(Old_attributes), New_attributes).

-spec build_key_map(list(sprocket@render:rendered_element())) -> gleam@map:map_(binary(), {integer(),
    sprocket@render:rendered_element()}).
build_key_map(Children) ->
    _pipe = Children,
    gleam@list:index_fold(
        _pipe,
        gleam@map:new(),
        fun(Acc, Child, Index) -> case Child of
                {rendered_element, _, {some, Key}, _, _} ->
                    gleam@map:insert(Acc, Key, {Index, Child});

                _ ->
                    Acc
            end end
    ).

-spec zip_all(list(LQA), list(LQC)) -> list({gleam@option:option(LQA),
    gleam@option:option(LQC)}).
zip_all(A, B) ->
    case {A, B} of
        {[], []} ->
            [];

        {[A@1 | Rest_a], [B@1 | Rest_b]} ->
            [{{some, A@1}, {some, B@1}} | zip_all(Rest_a, Rest_b)];

        {[A@2 | Rest_a@1], []} ->
            [{{some, A@2}, none} | zip_all(Rest_a@1, [])];

        {[], [B@2 | Rest_b@1]} ->
            [{none, {some, B@2}} | zip_all([], Rest_b@1)]
    end.

-spec op_code(patch(), boolean()) -> binary().
op_code(Op, Debug) ->
    case Debug of
        true ->
            case Op of
                no_op ->
                    <<"NoOp"/utf8>>;

                {update, _, _} ->
                    <<"Update"/utf8>>;

                {replace, _} ->
                    <<"Replace"/utf8>>;

                {insert, _} ->
                    <<"Insert"/utf8>>;

                remove ->
                    <<"Remove"/utf8>>;

                {change, _} ->
                    <<"Change"/utf8>>;

                {move, _, _} ->
                    <<"Move"/utf8>>
            end;

        false ->
            case Op of
                no_op ->
                    <<"0"/utf8>>;

                {update, _, _} ->
                    <<"1"/utf8>>;

                {replace, _} ->
                    <<"2"/utf8>>;

                {insert, _} ->
                    <<"3"/utf8>>;

                remove ->
                    <<"4"/utf8>>;

                {change, _} ->
                    <<"5"/utf8>>;

                {move, _, _} ->
                    <<"6"/utf8>>
            end
    end.

-spec attrs_to_json(list(sprocket@render:rendered_attribute())) -> gleam@json:json().
attrs_to_json(Attrs) ->
    _pipe = Attrs,
    _pipe@1 = gleam@list:flat_map(_pipe, fun(Attr) -> case Attr of
                {rendered_attribute, Name, Value} ->
                    [{Name, gleam@json:string(Value)}];

                {rendered_event_handler, Kind, Id} ->
                    [{gleam@string:concat(
                                [sprocket@internal@constants:constant(
                                        event_attr_prefix
                                    ),
                                    <<"-"/utf8>>,
                                    Kind]
                            ),
                            gleam@json:string(Id)}];

                {rendered_client_hook, Name@1, Id@1} ->
                    [{sprocket@internal@constants:constant(event_attr_prefix),
                            gleam@json:string(Name@1)},
                        {gleam@string:concat(
                                [sprocket@internal@constants:constant(
                                        event_attr_prefix
                                    ),
                                    <<"-id"/utf8>>]
                            ),
                            gleam@json:string(Id@1)}]
            end end),
    gleam@json:object(_pipe@1).

-spec map_index_fold(
    gleam@map:map_(LQJ, LQK),
    LQN,
    fun((LQN, LQK, LQJ, integer()) -> LQN)
) -> {LQN, integer()}.
map_index_fold(Map, Acc, Fold_fn) ->
    _pipe = Map,
    gleam@map:fold(
        _pipe,
        {Acc, 0},
        fun(Acc@1, Item, Key) ->
            {Acc@2, Index} = Acc@1,
            {Fold_fn(Acc@2, Key, Item, Index), Index + 1}
        end
    ).

-spec map_key_to_str({integer(), patch()}, boolean()) -> {binary(),
    gleam@json:json()}.
map_key_to_str(C, Debug) ->
    {Index, Patch} = C,
    {gleam@int:to_string(Index), patch_to_json(Patch, Debug)}.

-spec patch_to_json(patch(), boolean()) -> gleam@json:json().
patch_to_json(Patch, Debug) ->
    case Patch of
        no_op ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug))]
            );

        {update, Attrs, Children} ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug)),
                    gleam@json:nullable(Attrs, fun attrs_to_json/1),
                    gleam@json:nullable(
                        Children,
                        fun(_capture) -> children_to_json(_capture, Debug) end
                    )]
            );

        {replace, El} ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug)),
                    (erlang:element(2, sprocket@internal@render@json:renderer()))(
                        El
                    )]
            );

        {insert, El@1} ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug)),
                    (erlang:element(2, sprocket@internal@render@json:renderer()))(
                        El@1
                    )]
            );

        remove ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug))]
            );

        {change, Text} ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug)),
                    gleam@json:string(Text)]
            );

        {move, Index, Move_patch} ->
            gleam@json:preprocessed_array(
                [gleam@json:string(op_code(Patch, Debug)),
                    gleam@json:int(Index),
                    patch_to_json(Move_patch, Debug)]
            )
    end.

-spec children_to_json(list({integer(), patch()}), boolean()) -> gleam@json:json().
children_to_json(Children, Debug) ->
    _pipe = Children,
    _pipe@1 = gleam@list:map(
        _pipe,
        fun(_capture) -> map_key_to_str(_capture, Debug) end
    ),
    gleam@json:object(_pipe@1).

-spec compare_child_at_index(
    gleam@map:map_(integer(), patch()),
    list(sprocket@render:rendered_element()),
    sprocket@render:rendered_element(),
    integer()
) -> gleam@map:map_(integer(), patch()).
compare_child_at_index(Acc, Old_children, New_child, Index) ->
    case gleam@list:at(Old_children, Index) of
        {ok, Old_child} ->
            case create(Old_child, New_child) of
                no_op ->
                    Acc;

                Patch ->
                    gleam@map:insert(Acc, Index, Patch)
            end;

        {error, nil} ->
            gleam@map:insert(Acc, Index, {insert, New_child})
    end.

-spec create(
    sprocket@render:rendered_element(),
    sprocket@render:rendered_element()
) -> patch().
create(Old, New) ->
    case {Old, New} of
        {{rendered_element, Old_tag, Old_key, Old_attrs, Old_children},
            {rendered_element, New_tag, New_key, New_attrs, New_children}} when Old_tag =:= New_tag ->
            case Old_key =:= New_key of
                true ->
                    case compare_attributes(Old_attrs, New_attrs) of
                        {some, Attrs} ->
                            {update,
                                {some, Attrs},
                                compare_children(Old_children, New_children)};

                        none ->
                            case compare_children(Old_children, New_children) of
                                {some, Children} ->
                                    {update, none, {some, Children}};

                                none ->
                                    no_op
                            end
                    end;

                false ->
                    {replace, New}
            end;

        {{rendered_component, Old_fc, _, Old_props, _, Old_children@1},
            {rendered_component, New_fc, _, New_props, _, New_children@1}} when (Old_fc =:= New_fc) andalso (Old_props =:= New_props) ->
            case compare_children(Old_children@1, New_children@1) of
                {some, Children@1} ->
                    {update, none, {some, Children@1}};

                none ->
                    no_op
            end;

        {{rendered_text, Old_text}, {rendered_text, New_text}} ->
            case Old_text =:= New_text of
                true ->
                    no_op;

                false ->
                    {change, New_text}
            end;

        {_, _} ->
            {replace, New}
    end.

-spec compare_children(
    list(sprocket@render:rendered_element()),
    list(sprocket@render:rendered_element())
) -> gleam@option:option(list({integer(), patch()})).
compare_children(Old_children, New_children) ->
    Old_key_map = build_key_map(Old_children),
    New_key_map = build_key_map(New_children),
    Removals = begin
        _pipe = zip_all(Old_children, New_children),
        gleam@list:index_fold(
            _pipe,
            gleam@map:new(),
            fun(Acc, Child, Index) -> case Child of
                    {{some, {rendered_element, _, {some, Old_key}, _, _}},
                        {some, {rendered_element, _, {some, _}, _, _}}} ->
                        case gleam@map:get(New_key_map, Old_key) of
                            {ok, _} ->
                                Acc;

                            {error, nil} ->
                                gleam@map:insert(Acc, Index, remove)
                        end;

                    {_, none} ->
                        gleam@map:insert(Acc, Index, remove);

                    _ ->
                        Acc
                end end
        )
    end,
    _pipe@1 = New_children,
    _pipe@2 = gleam@list:index_fold(
        _pipe@1,
        Removals,
        fun(Acc@1, New_child, Index@1) -> case New_child of
                {rendered_element, _, {some, Key}, _, _} ->
                    case gleam@map:get(Old_key_map, Key) of
                        {ok, Found} ->
                            {Old_index, Old_child} = Found,
                            Child_patch = create(Old_child, New_child),
                            case Index@1 =:= Old_index of
                                true ->
                                    gleam@map:insert(
                                        Acc@1,
                                        Index@1,
                                        Child_patch
                                    );

                                false ->
                                    gleam@map:insert(
                                        Acc@1,
                                        Index@1,
                                        {move, Old_index, Child_patch}
                                    )
                            end;

                        {error, nil} ->
                            compare_child_at_index(
                                Acc@1,
                                Old_children,
                                New_child,
                                Index@1
                            )
                    end;

                _ ->
                    compare_child_at_index(
                        Acc@1,
                        Old_children,
                        New_child,
                        Index@1
                    )
            end end
    ),
    _pipe@3 = gleam@map:filter(_pipe@2, fun(_, Child_el) -> case Child_el of
                no_op ->
                    false;

                _ ->
                    true
            end end),
    (fun(Diff_map) -> case gleam@map:size(Diff_map) > 0 of
            true ->
                {some, gleam@map:to_list(Diff_map)};

            false ->
                none
        end end)(_pipe@3).