-module(size_comparison).
-export([run/0]).

run() ->
    application:ensure_all_started(gmserialization),
    code:add_path("asn1"),

    io:format("=== Size Comparison: Legacy RLP vs DER ===~n~n"),

    Compare = fun(Desc, LegacyBin, DerBin) ->
        L = byte_size(LegacyBin),
        D = byte_size(DerBin),
        Overhead = D - L,
        Pct = case L of 0 -> 0; _ -> round(Overhead * 100 / L) end,
        io:format("~s~n", [Desc]),
        io:format("  Legacy: ~p bytes  ~w~n", [L, LegacyBin]),
        Show = binary:part(DerBin, 0, min(18, D)),
        io:format("  DER:    ~p bytes  ~w~n", [D, Show]),
        io:format("  Overhead: +~p bytes (~p%)~n~n", [Overhead, Pct])
    end,

    %% Case 1: tag+vsn + small int + small binary
    T1 = [{foo,int},{bar,binary}],
    V1 = [{foo,1},{bar,<<2>>}],
    Leg1 = gmser_chain_objects:serialize(account, 1, T1, V1),
    DerVal1 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"foo">>, {intValue, 1}},
        {'TemplateField', <<"bar">>, {binaryValue, <<2>>}}
    ]}},
    {ok, Der1} = 'GajumaruSerialization':encode('GajumaruData', DerVal1),
    Compare("Case 1: tag+vsn + small int + tiny binary (2 fields)", Leg1, Der1),

    %% Case 2: zero + empty binary
    V2 = [{foo,0},{bar,<<>>}],
    Leg2 = gmser_chain_objects:serialize(account, 1, T1, V2),
    DerVal2 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"foo">>, {intValue, 0}},
        {'TemplateField', <<"bar">>, {binaryValue, <<>>}}
    ]}},
    {ok, Der2} = 'GajumaruSerialization':encode('GajumaruData', DerVal2),
    Compare("Case 2: zero int + empty binary", Leg2, Der2),

    %% Case 3: list of ints
    T3 = [{xs,[int]}],
    V3 = [{xs,[1,2,3]}],
    Leg3 = gmser_chain_objects:serialize(account, 1, T3, V3),
    DerVal3 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"xs">>, {listValue, [
            {intValue,1},{intValue,2},{intValue,3}
        ]}}
    ]}},
    {ok, Der3} = 'GajumaruSerialization':encode('GajumaruData', DerVal3),
    Compare("Case 3: list of 3 small ints", Leg3, Der3),

    %% Case 4: tuple (int, binary)
    T4 = [{p,{int,binary}}],
    V4 = [{p,{42,<<"hi">>}}],
    Leg4 = gmser_chain_objects:serialize(account, 1, T4, V4),
    DerVal4 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"p">>, {tupleValue, [
            {intValue,42}, {binaryValue,<<"hi">>}
        ]}}
    ]}},
    {ok, Der4} = 'GajumaruSerialization':encode('GajumaruData', DerVal4),
    Compare("Case 4: fixed tuple (int + 2-byte binary)", Leg4, Der4),

    %% Case 5: 256-byte payload
    Bin5 = crypto:strong_rand_bytes(256),
    T5 = [{data,binary}],
    V5 = [{data,Bin5}],
    Leg5 = gmser_chain_objects:serialize(account, 1, T5, V5),
    DerVal5 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"data">>, {binaryValue, Bin5}}
    ]}},
    {ok, Der5} = 'GajumaruSerialization':encode('GajumaruData', DerVal5),
    Compare("Case 5: 256-byte binary payload only", Leg5, Der5),

    %% Case 6: Concrete SignedTx style (no field names in DER)
    T6 = [{signatures,[binary]},{tx,binary}],
    V6 = [{signatures,[<<"sig1">>,<<"sig2">>]},{tx,<<"txbody123">>}],
    Leg6 = gmser_chain_objects:serialize(signed_tx, 1, T6, V6),
    DerVal6 = {'GajumaruData', 11, 1, {signedTx, {'SignedTx',
        [<<"sig1">>, <<"sig2">>], <<"txbody123">>}}},
    {ok, Der6} = 'GajumaruSerialization':encode('GajumaruData', DerVal6),
    Compare("Case 6: SignedTx-like (concrete DER, no names)", Leg6, Der6),

    %% Case 7: 33-byte id-like value
    IdBin = <<1, 0:256>>,
    T7 = [{owner,binary}],
    V7 = [{owner,IdBin}],
    Leg7 = gmser_chain_objects:serialize(account, 1, T7, V7),
    DerVal7 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"owner">>, {binaryValue, IdBin}}
    ]}},
    {ok, Der7} = 'GajumaruSerialization':encode('GajumaruData', DerVal7),
    Compare("Case 7: 33-byte value (id-like)", Leg7, Der7),

    %% Case 8: Deeper nesting / more fields
    T8 = [{a,int},{b,binary},{c,[int]},{d,{int,int}}],
    V8 = [{a,123456},{b,<<"abcdef">>},{c,[10,20,30]},{d,{7,8}}],
    Leg8 = gmser_chain_objects:serialize(account, 1, T8, V8),
    DerVal8 = {'GajumaruData', 10, 1, {templateFields, [
        {'TemplateField', <<"a">>, {intValue, 123456}},
        {'TemplateField', <<"b">>, {binaryValue, <<"abcdef">>}},
        {'TemplateField', <<"c">>, {listValue, [{intValue,10},{intValue,20},{intValue,30}]}},
        {'TemplateField', <<"d">>, {tupleValue, [{intValue,7},{intValue,8}]}}
    ]}},
    {ok, Der8} = 'GajumaruSerialization':encode('GajumaruData', DerVal8),
    Compare("Case 8: 4 fields mixed (int, bin, list, tuple)", Leg8, Der8),

    io:format("=== Analysis ===~n"),
    io:format("Note: Generic templateFields path includes IA5String field names.~n"),
    io:format("Concrete types (e.g. SignedTx) avoid name overhead.~n"),
    ok.