-module(trove@internal@btree@diff).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/trove/internal/btree/diff.gleam").
-export([diff/6]).
-export_type([entry/1]).

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

?MODULEDOC(false).

-type entry(OBC) :: {upserted, OBC} | removed.

-file("src/trove/internal/btree/diff.gleam", 73).
?DOC(false).
-spec do_merge_step(
    gleam@yielder:step({OBT, OBU}, gleam@yielder:yielder({OBT, OBU})),
    gleam@yielder:step({OBT, OBU}, gleam@yielder:yielder({OBT, OBU})),
    fun((OBT, OBT) -> gleam@order:order())
) -> gleam@yielder:step({OBT, entry(OBU)}, {gleam@yielder:step({OBT, OBU}, gleam@yielder:yielder({OBT,
        OBU})),
    gleam@yielder:step({OBT, OBU}, gleam@yielder:yielder({OBT, OBU}))}).
do_merge_step(Old_step, New_step, Compare) ->
    case {Old_step, New_step} of
        {done, done} ->
            done;

        {done, {next, {New_key, New_value}, New_rest}} ->
            {next,
                {New_key, {upserted, New_value}},
                {done, gleam@yielder:step(New_rest)}};

        {{next, {Old_key, _}, Old_rest}, done} ->
            {next, {Old_key, removed}, {gleam@yielder:step(Old_rest), done}};

        {{next, {Old_key@1, Old_value}, Old_rest@1},
            {next, {New_key@1, New_value@1}, New_rest@1}} ->
            case Compare(Old_key@1, New_key@1) of
                lt ->
                    {next,
                        {Old_key@1, removed},
                        {gleam@yielder:step(Old_rest@1), New_step}};

                gt ->
                    {next,
                        {New_key@1, {upserted, New_value@1}},
                        {Old_step, gleam@yielder:step(New_rest@1)}};

                eq ->
                    case Old_value =:= New_value@1 of
                        true ->
                            do_merge_step(
                                gleam@yielder:step(Old_rest@1),
                                gleam@yielder:step(New_rest@1),
                                Compare
                            );

                        false ->
                            {next,
                                {New_key@1, {upserted, New_value@1}},
                                {gleam@yielder:step(Old_rest@1),
                                    gleam@yielder:step(New_rest@1)}}
                    end
            end
    end.

-file("src/trove/internal/btree/diff.gleam", 62).
?DOC(false).
-spec lazy_merge_diff(
    gleam@yielder:yielder({OBN, OBO}),
    gleam@yielder:yielder({OBN, OBO}),
    fun((OBN, OBN) -> gleam@order:order())
) -> gleam@yielder:yielder({OBN, entry(OBO)}).
lazy_merge_diff(Old, New, Compare) ->
    gleam@yielder:unfold(
        {gleam@yielder:step(Old), gleam@yielder:step(New)},
        fun(State) ->
            {Old_step, New_step} = State,
            do_merge_step(Old_step, New_step, Compare)
        end
    ).

-file("src/trove/internal/btree/diff.gleam", 23).
?DOC(false).
-spec diff(
    trove@internal@btree:btree(OBD, OBE),
    trove@internal@btree:btree(OBD, OBE),
    trove@internal@store:store(),
    trove@codec:codec(OBD),
    trove@codec:codec(OBE),
    fun((OBD, OBD) -> gleam@order:order())
) -> gleam@yielder:yielder({OBD, entry(OBE)}).
diff(Old, New, Store, Key_codec, Value_codec, Compare) ->
    gleam@bool:guard(
        trove@internal@btree:root(Old) =:= trove@internal@btree:root(New),
        gleam@yielder:empty(),
        fun() ->
            Old_yielder = trove@internal@btree@range:'query'(
                Old,
                Store,
                none,
                none,
                forward,
                Key_codec,
                Value_codec,
                Compare
            ),
            New_yielder = trove@internal@btree@range:'query'(
                New,
                Store,
                none,
                none,
                forward,
                Key_codec,
                Value_codec,
                Compare
            ),
            lazy_merge_diff(Old_yielder, New_yielder, Compare)
        end
    ).