database

-module(database).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).
-define(FILEPATH, "src\\database.gleam").
-export([create_table/2, transaction/2, insert/2, update/3, delete/2, find/2, drop_table/1, select/2, migrate/2, field/3, enum/2]).
-export_type([storage/0, table_attributes/0, table_ref/1, transaction/1, table/1, file_error/0, find_error/0, select_option/1, migrate_options/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(
    " An outrageously simple set of functions to interact with the BEAM\n"
    " DETS (Disk-based Erlang Term Storage) API.\n"
    " \n"
    " Good for small projects and POCs.\n"
    "\n"
    "\n"
    " This project DOES NOT intend to serve as direct bindings to the \n"
    " DETS API, but rather to interact with it in a gleamy way:\n"
    "   1. with a simple and concise interface;\n"
    "   2. type-safely;\n"
    "   3. no unexpected crashes, all errors are values.\n"
).

-type storage() :: set.

-type table_attributes() :: {file, gleam@erlang@charlist:charlist()} |
    {type, storage()} |
    {keypos, integer()}.

-type table_ref(EIF) :: any() | {gleam_phantom, EIF}.

-opaque transaction(EIG) :: {transaction,
        table_ref({binary(), EIG}),
        gleam@dynamic@decode:decoder(EIG)}.

-opaque table(EIH) :: {table,
        gleam@erlang@atom:atom_(),
        list(table_attributes()),
        gleam@erlang@charlist:charlist(),
        gleam@dynamic@decode:decoder(EIH)}.

-type file_error() :: unable_to_open | unable_to_close.

-type find_error() :: not_found |
    {unable_to_decode, list(gleam@dynamic@decode:decode_error())}.

-type select_option(EII) :: skip | {continue, EII} | {done, EII}.

-type migrate_options(EIJ) :: {update, EIJ} | keep | delete.

-file("src\\database.gleam", 128).
?DOC(
    " Creats a table.\n"
    "\n"
    " If no .dets file exists for the provided definition, creates one.\n"
    " Otherwise, just checks whether the file is accessible and not\n"
    " corrupted.\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn start_database() {\n"
    "   let table_decoder = {\n"
    "     use name <- database.field(0, decode.string)\n"
    "     use animal <- database.field(1, my_animal_decoder)\n"
    "     decode.success(Pet(name:, animal:))\n"
    "   }\n"
    "   let table_name = atom.create(\"pets\")\n"
    "   database.create_table(name: table_name, decode_with: table_decoder)\n"
    "   // -> Ok(Table(Pet))\n"
    " }\n"
    " ```\n"
).
-spec create_table(gleam@erlang@atom:atom_(), gleam@dynamic@decode:decoder(EJW)) -> {ok,
        table(EJW)} |
    {error, file_error()}.
create_table(Name, Decoder) ->
    Path = unicode:characters_to_list(
        <<(erlang:atom_to_binary(Name))/binary, ".dets"/utf8>>
    ),
    Att = [{file, Path}, {type, set}, {keypos, 1}],
    case dets:open_file(Name, Att) of
        {ok, Tab} ->
            case dets:close(Tab) of
                {error, _} ->
                    {error, unable_to_close};

                _ ->
                    {ok, {table, Name, Att, Path, Decoder}}
            end;

        {error, _} ->
            {error, unable_to_open}
    end.

-file("src\\database.gleam", 165).
?DOC(
    " Allows you to interact with the table.\n"
    "\n"
    " It opens and locks the .dets file, then execute your operations.\n"
    " Once the operations are done, it writes the changes into the file,\n"
    " closes and releases it.\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn is_pet_registered(table: Table(Pet), pet_id: String) {\n"
    "   use ref <- database.transaction(table)\n"
    "   case database.find(ref, pet_id) {\n"
    "     Ok(_) -> True\n"
    "     Error(_) -> False\n"
    "   }\n"
    " }\n"
    " ```\n"
).
-spec transaction(table(EKB), fun((transaction(EKB)) -> EKE)) -> {ok, EKE} |
    {error, file_error()}.
transaction(Table, Procedure) ->
    case dets:open_file(erlang:element(2, Table), erlang:element(3, Table)) of
        {error, _} ->
            {error, unable_to_open};

        {ok, Ref} ->
            Resp = Procedure({transaction, Ref, erlang:element(5, Table)}),
            case dets:close(Ref) of
                {error, _} ->
                    {error, unable_to_close};

                _ ->
                    {ok, Resp}
            end
    end.

-file("src\\database.gleam", 193).
?DOC(
    " Inserts a value into a table and return their generated id.\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn new_pet(table: Table(Pet), animal: Animal, name: String) -> String {\n"
    "   let pet = Pet(name, animal)\n"
    "   use ref <- database.transaction(table)\n"
    "   database.insert(ref, pet)  \n"
    " }\n"
    " ```\n"
).
-spec insert(transaction(EKH), EKH) -> {ok, binary()} | {error, nil}.
insert(Transac, Value) ->
    Id = begin
        _pipe = crypto:strong_rand_bytes(16),
        gleam@bit_array:base64_url_encode(_pipe, false)
    end,
    case dets:insert(erlang:element(2, Transac), {Id, Value}) of
        {error, _} ->
            {error, nil};

        _ ->
            {ok, Id}
    end.

-file("src\\database.gleam", 213).
?DOC(
    " Updates a value in a table.\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn rename_pet(table: Table(Pet) id: String, pet: Pet, new_name: String) {\n"
    "   use transac <- database.transaction(table)\n"
    "   let pet = Pet(new_name, pet.animal)\n"
    "   database.update(transac, id, pet)\n"
    " }\n"
    " ```\n"
).
-spec update(transaction(EKK), binary(), EKK) -> {ok, binary()} | {error, nil}.
update(Transac, Id, Value) ->
    case dets:lookup(erlang:element(2, Transac), Id) of
        [_] ->
            case dets:insert(erlang:element(2, Transac), {Id, Value}) of
                {error, _} ->
                    {error, nil};

                _ ->
                    {ok, Id}
            end;

        _ ->
            {error, nil}
    end.

-file("src\\database.gleam", 235).
?DOC(
    " Deletes a value from a table.\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn delete_pet(table: Table(Pet) pet_id: String) {\n"
    "   use ref <- database.transaction(table)\n"
    "   database.delete(ref, pet_id)\n"
    " }\n"
    " ```\n"
).
-spec delete(transaction(any()), binary()) -> {ok, nil} | {error, nil}.
delete(Transac, Id) ->
    case dets:delete(erlang:element(2, Transac), Id) of
        {error, _} ->
            {error, nil};

        _ ->
            {ok, nil}
    end.

-file("src\\database.gleam", 257).
?DOC(
    " Finds a value by its index\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn play_with_pluto(table: Table(Pet)) {\n"
    "   use ref <- database.transaction(table)\n"
    "   let resp = database.find(ref, known_pluto_id)\n"
    "   case resp {\n"
    "     Error(_) -> Error(PlutoNotFoundBlameTheAstronomers)\n"
    "     Ok(pluto) -> Ok(play_with(pluto))\n"
    "   }\n"
    " }\n"
    " ```\n"
).
-spec find(transaction(EKQ), binary()) -> {ok, EKQ} | {error, find_error()}.
find(Transac, Id) ->
    case dets:lookup(erlang:element(2, Transac), Id) of
        [{_, Resp}] ->
            case gleam@dynamic@decode:run(Resp, erlang:element(3, Transac)) of
                {ok, Val} ->
                    {ok, Val};

                {error, Errors} ->
                    {error, {unable_to_decode, Errors}}
            end;

        _ ->
            {error, not_found}
    end.

-file("src\\database.gleam", 284).
?DOC(
    " Deletes the entire table file\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn destroy_all_pets(table: Table(Pet), password: String) {\n"
    "   case password {\n"
    "     \"Yes, I am evil.\" -> {\n"
    "       database.drop_table(table)\n"
    "       Ok(Nil)\n"
    "     }\n"
    "     _ -> Error(WrongPassword)\n"
    "   }\n"
    " }\n"
    " ```\n"
).
-spec drop_table(table(any())) -> {ok, nil} | {error, nil}.
drop_table(Table) ->
    case file:delete(erlang:element(4, Table)) of
        {error, _} ->
            {error, nil};

        _ ->
            {ok, nil}
    end.

-file("src\\database.gleam", 325).
?DOC(
    " Searches for somethig on the table.\n"
    "\n"
    " # Example\n"
    " \n"
    " ```gleam\n"
    " pub fn fetch_all_parrots(table: Table(Pet)) {\n"
    "   use ref <- database.transaction(table)\n"
    "   use value <- database.select(ref)\n"
    "   case value {\n"
    "     #(_id, Pet(_name, Parrot)) -> Continue(value)\n"
    "     _ -> Skip\n"
    "   }\n"
    " }\n"
    " ```\n"
    "\n"
    " # IMPORTANT\n"
    " **DETS tables are not sorted in any deterministic way, so\n"
    " never assume that the last value inserted will be the last\n"
    " one on the table.**\n"
).
-spec select(transaction(EKX), fun(({binary(), EKX}) -> select_option(EKZ))) -> list(EKZ).
select(Transac, Select_fn) ->
    New_fn = fun(Tab_value) ->
        {Id, Dyn_value} = Tab_value,
        case gleam@dynamic@decode:run(Dyn_value, erlang:element(3, Transac)) of
            {ok, Value} ->
                case Select_fn({Id, Value}) of
                    skip ->
                        database_ffi:skip();

                    Res ->
                        Res
                end;

            _ ->
                database_ffi:skip()
        end
    end,
    dets:traverse(erlang:element(2, Transac), New_fn).

-file("src\\database.gleam", 381).
?DOC(
    " Migrates the table to a new structure.\n"
    " When the type stored in the table changes, this function\n"
    " allows you to update the table to the new structure.\n"
    "\n"
    " # IMPORTANT\n"
    " **To avoid conflicts, this function will start its own\n"
    " transaction, so you should not use it inside another.**\n"
    "\n"
    " # Example\n"
    "\n"
    " ```gleam\n"
    " pub fn migrate_pets(table: Table(Pet)) {\n"
    "   use value <- database.migrate(table)\n"
    "   case decode.run(value, my_pet_decoder()) {\n"
    "     Ok(pet) -> Update(pet)\n"
    "     _ -> Delete\n"
    "   } \n"
    " }\n"
    " ```\n"
).
-spec migrate(
    table(ELC),
    fun((gleam@dynamic:dynamic_()) -> migrate_options(ELC))
) -> {ok, nil} | {error, file_error()}.
migrate(Table, Migration) ->
    transaction(
        Table,
        fun(Transac) ->
            Func = fun(Tab_value) ->
                {Id, Dyn_value} = Tab_value,
                case Migration(Dyn_value) of
                    {update, New_value} ->
                        _ = dets:insert(
                            erlang:element(2, Transac),
                            {Id, New_value}
                        ),
                        database_ffi:skip();

                    delete ->
                        _ = dets:delete(erlang:element(2, Transac), Id),
                        database_ffi:skip();

                    keep ->
                        database_ffi:skip()
                end
            end,
            _ = dets:traverse(erlang:element(2, Transac), Func),
            nil
        end
    ).

-file("src\\database.gleam", 416).
?DOC(
    " Field decoder\n"
    " \n"
    " # Example\n"
    " \n"
    " ```gleam\n"
    " let decoder = {\n"
    "   use name <- database.field(0, decode.string)\n"
    "   use animal <- database.field(1, my_animal_decoder)\n"
    "   decode.success(Pet(name:, animal:))\n"
    " }\n"
    " ```\n"
).
-spec field(
    integer(),
    gleam@dynamic@decode:decoder(ELH),
    fun((ELH) -> gleam@dynamic@decode:decoder(ELJ))
) -> gleam@dynamic@decode:decoder(ELJ).
field(Field_index, Field_decoder, Next) ->
    gleam@dynamic@decode:field(Field_index + 1, Field_decoder, Next).

-file("src\\database.gleam", 437).
?DOC(
    " Enum decoder\n"
    " \n"
    " # Example\n"
    " \n"
    " ```gleam\n"
    " let decoder = {\n"
    "   use name <- database.field(0, decode.string)\n"
    "   use animal <- database.field(1, database.enum([Dog, Cat, Parrot], Dog))\n"
    "   decode.success(Pet(name:, animal:))\n"
    " }\n"
    " ```\n"
).
-spec enum(list(ELM), ELM) -> gleam@dynamic@decode:decoder(ELM).
enum(Values, Zero_value) ->
    gleam@dynamic@decode:new_primitive_decoder(
        <<"Enum"/utf8>>,
        fun(Data) ->
            case gleam@list:find(
                Values,
                fun(_capture) -> database_ffi:compare(_capture, Data) end
            ) of
                {ok, Value} ->
                    {ok, Value};

                {error, _} ->
                    {error, Zero_value}
            end
        end
    ).