-module(spectra_string).

-export([from_string/4, to_string/4]).

-ignore_xref([
    {spectra_string, from_string, 4},
    {spectra_string, to_string, 4}
]).

-include("../include/spectra_internal.hrl").

%% API

-doc """
Converts a string value to an Erlang value based on a type specification.

This function validates the given string value against the specified type definition
and converts it to the corresponding Erlang value.

### Returns
{ok, ErlangValue} if conversion succeeds, or {error, Errors} if validation fails
""".
-doc #{
    params =>
        #{
            "Config" => "Runtime configuration",
            "String" => "The string value to convert to Erlang format",
            "Type" => "The type specification (spectra:sp_type())",
            "TypeInfo" => "The type information containing type definitions"
        }
}.

-spec from_string(
    TypeInfo :: spectra:type_info(),
    Type :: spectra:sp_type(),
    String :: list(),
    Config :: spectra:sp_config()
) ->
    {ok, dynamic()} | {error, [spectra:error()]}.
from_string(
    TypeInfo,
    #sp_user_type_ref{type_name = TypeName, variables = Args, arity = Arity} = UserTypeRef,
    String,
    Config
) ->
    TypeRef = {type, TypeName, Arity},
    Module = spectra_type_info:get_module(TypeInfo),
    case
        spectra_codec:try_codec_decode(
            string, TypeInfo, Module, TypeRef, UserTypeRef, String, Config
        )
    of
        continue ->
            Type = spectra_type_info:get_type(TypeInfo, TypeName, Arity),
            TypeWithoutVars = spectra_util:apply_args(TypeInfo, Type, Args),
            from_string(TypeInfo, TypeWithoutVars, String, Config);
        Result ->
            Result
    end;
from_string(TypeInfo, #sp_rec_ref{record_name = RecordName} = RecordRef, String, Config) ->
    TypeRef = {record, RecordName},
    Module = spectra_type_info:get_module(TypeInfo),
    case
        spectra_codec:try_codec_decode(string, TypeInfo, Module, TypeRef, RecordRef, String, Config)
    of
        continue ->
            RecordType = spectra_type_info:get_record(TypeInfo, RecordName),
            erlang:error({type_not_supported, RecordType});
        Result ->
            Result
    end;
from_string(
    TypeInfo,
    #sp_remote_type{mfargs = {Module, TypeName, Args}, arity = TypeArity} = RemoteRef,
    String,
    Config
) ->
    TypeRef = {type, TypeName, TypeArity},
    case
        spectra_codec:try_codec_decode(string, TypeInfo, Module, TypeRef, RemoteRef, String, Config)
    of
        continue ->
            RemoteTypeInfo = spectra_module_types:get(Module, Config),
            RemoteType = spectra_type_info:get_type(RemoteTypeInfo, TypeName, TypeArity),
            TypeWithoutVars = spectra_util:apply_args(RemoteTypeInfo, RemoteType, Args),
            from_string(RemoteTypeInfo, TypeWithoutVars, String, Config);
        Result ->
            Result
    end;
from_string(_TypeInfo, #sp_simple_type{type = NotSupported} = T, _String, _Config) when
    NotSupported =:= pid orelse
        NotSupported =:= port orelse
        NotSupported =:= reference orelse
        NotSupported =:= bitstring orelse
        NotSupported =:= nonempty_bitstring orelse
        NotSupported =:= none
->
    erlang:error({type_not_supported, T});
from_string(_TypeInfo, #sp_simple_type{type = PrimaryType}, String, _Config) ->
    convert_string_to_type(PrimaryType, String);
from_string(
    _TypeInfo,
    #sp_range{
        type = integer,
        lower_bound = Min,
        upper_bound = Max
    } =
        Range,
    String,
    _Config
) ->
    case convert_string_to_type(integer, String) of
        {ok, Value} when Min =< Value, Value =< Max ->
            {ok, Value};
        {ok, Value} when is_integer(Value) ->
            {error, [sp_error:type_mismatch(Range, Value)]};
        {error, Reason} ->
            {error, Reason}
    end;
from_string(_TypeInfo, #sp_literal{value = Literal}, String, _Config) ->
    try_convert_string_to_literal(Literal, String);
from_string(TypeInfo, #sp_union{} = Type, String, Config) ->
    union(fun from_string/4, TypeInfo, Type, String, Config);
from_string(_TypeInfo, #sp_rec{} = T, _String, _Config) ->
    erlang:error({type_not_supported, T});
from_string(_TypeInfo, Type, String, _Config) ->
    {error, [sp_error:type_mismatch(Type, String)]}.

-doc """
Converts an Erlang value to a string based on a type specification.

This function validates the given Erlang value against the specified type definition
and converts it to a string representation.

### Returns
{ok, String} if conversion succeeds, or {error, Errors} if validation fails
""".
-doc #{
    params =>
        #{
            "Config" => "Runtime configuration",
            "Data" => "The Erlang value to convert to string format",
            "Type" => "The type specification (spectra:sp_type())",
            "TypeInfo" => "The type information containing type definitions"
        }
}.

-spec to_string(
    TypeInfo :: spectra:type_info(),
    Type :: spectra:sp_type(),
    Data :: dynamic(),
    Config :: spectra:sp_config()
) ->
    {ok, string()} | {error, [spectra:error()]}.
to_string(
    TypeInfo,
    #sp_user_type_ref{type_name = TypeName, variables = Args, arity = Arity} = UserTypeRef,
    Data,
    Config
) ->
    TypeRef = {type, TypeName, Arity},
    Module = spectra_type_info:get_module(TypeInfo),
    case
        spectra_codec:try_codec_encode(string, TypeInfo, Module, TypeRef, UserTypeRef, Data, Config)
    of
        continue ->
            Type = spectra_type_info:get_type(TypeInfo, TypeName, Arity),
            TypeWithoutVars = spectra_util:apply_args(TypeInfo, Type, Args),
            to_string(TypeInfo, TypeWithoutVars, Data, Config);
        Result ->
            Result
    end;
to_string(TypeInfo, #sp_rec_ref{record_name = RecordName} = RecordRef, Data, Config) ->
    TypeRef = {record, RecordName},
    Module = spectra_type_info:get_module(TypeInfo),
    case
        spectra_codec:try_codec_encode(string, TypeInfo, Module, TypeRef, RecordRef, Data, Config)
    of
        continue ->
            RecordType = spectra_type_info:get_record(TypeInfo, RecordName),
            erlang:error({type_not_supported, RecordType});
        Result ->
            Result
    end;
to_string(
    TypeInfo,
    #sp_remote_type{mfargs = {Module, TypeName, Args}, arity = TypeArity} = RemoteRef,
    Data,
    Config
) ->
    TypeRef = {type, TypeName, TypeArity},
    case
        spectra_codec:try_codec_encode(string, TypeInfo, Module, TypeRef, RemoteRef, Data, Config)
    of
        continue ->
            RemoteTypeInfo = spectra_module_types:get(Module, Config),
            RemoteType = spectra_type_info:get_type(RemoteTypeInfo, TypeName, TypeArity),
            TypeWithoutVars = spectra_util:apply_args(RemoteTypeInfo, RemoteType, Args),
            to_string(RemoteTypeInfo, TypeWithoutVars, Data, Config);
        Result ->
            Result
    end;
to_string(_TypeInfo, #sp_simple_type{type = NotSupported} = T, _Data, _Config) when
    NotSupported =:= pid orelse
        NotSupported =:= port orelse
        NotSupported =:= reference orelse
        NotSupported =:= bitstring orelse
        NotSupported =:= nonempty_bitstring orelse
        NotSupported =:= none
->
    erlang:error({type_not_supported, T});
to_string(_TypeInfo, #sp_simple_type{type = PrimaryType}, Data, _Config) ->
    convert_type_to_string(PrimaryType, Data);
to_string(
    _TypeInfo,
    #sp_range{
        type = integer,
        lower_bound = Min,
        upper_bound = Max
    } =
        Range,
    Data,
    _Config
) ->
    case convert_type_to_string(integer, Data) of
        {ok, String} when Min =< Data, Data =< Max ->
            {ok, String};
        {ok, _String} when is_integer(Data) ->
            {error, [sp_error:type_mismatch(Range, Data)]};
        {error, Reason} ->
            {error, Reason}
    end;
to_string(_TypeInfo, #sp_literal{value = Literal}, Data, _Config) ->
    try_convert_literal_to_string(Literal, Data);
to_string(TypeInfo, #sp_union{} = Type, Data, Config) ->
    union(fun to_string/4, TypeInfo, Type, Data, Config);
to_string(_TypeInfo, #sp_rec{} = T, _Data, _Config) ->
    erlang:error({type_not_supported, T});
to_string(_TypeInfo, Type, Data, _Config) ->
    {error, [sp_error:type_mismatch(Type, Data)]}.

%% INTERNAL
-spec convert_string_to_type(
    Type :: spectra:simple_types(),
    String :: string()
) ->
    {ok, dynamic()} | {error, [spectra:error()]}.
convert_string_to_type(Type, String) when is_atom(Type), is_list(String) ->
    do_convert_string_to_type(Type, String);
convert_string_to_type(Type, NotString) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = Type}, NotString)]}.

-spec do_convert_string_to_type(Type :: spectra:simple_types(), String :: string()) ->
    {ok, dynamic()} | {error, [spectra:error()]}.
do_convert_string_to_type(integer, String) ->
    try
        {ok, list_to_integer(String)}
    catch
        error:badarg ->
            {error, [sp_error:type_mismatch(#sp_simple_type{type = integer}, String)]}
    end;
do_convert_string_to_type(float, String) ->
    try
        {ok, list_to_float(String)}
    catch
        error:badarg ->
            {error, [sp_error:type_mismatch(#sp_simple_type{type = float}, String)]}
    end;
do_convert_string_to_type(number, String) ->
    case do_convert_string_to_type(integer, String) of
        {ok, _} = Result ->
            Result;
        {error, _} ->
            do_convert_string_to_type(float, String)
    end;
do_convert_string_to_type(boolean, "true") ->
    {ok, true};
do_convert_string_to_type(boolean, "false") ->
    {ok, false};
do_convert_string_to_type(boolean, String) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = boolean}, String)]};
do_convert_string_to_type(atom, String) ->
    try
        {ok, list_to_existing_atom(String)}
    catch
        error:badarg ->
            {error, [sp_error:type_mismatch(#sp_simple_type{type = atom}, String)]}
    end;
do_convert_string_to_type(string, String) ->
    {ok, String};
do_convert_string_to_type(nonempty_string, String) when String =/= [] ->
    {ok, String};
do_convert_string_to_type(nonempty_string, []) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = nonempty_string}, [])]};
do_convert_string_to_type(binary, String) ->
    encode_utf8_binary(binary, String);
do_convert_string_to_type(nonempty_binary, String) when String =/= [] ->
    encode_utf8_binary(nonempty_binary, String);
do_convert_string_to_type(nonempty_binary, []) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = nonempty_binary}, [])]};
do_convert_string_to_type(non_neg_integer, String) ->
    case do_convert_string_to_type(integer, String) of
        {ok, Value} when Value >= 0 ->
            {ok, Value};
        {ok, Value} ->
            {error, [sp_error:type_mismatch(#sp_simple_type{type = non_neg_integer}, Value)]};
        {error, Reason} ->
            {error, Reason}
    end;
do_convert_string_to_type(pos_integer, String) ->
    case do_convert_string_to_type(integer, String) of
        {ok, Value} when Value > 0 ->
            {ok, Value};
        {ok, Value} ->
            {error, [sp_error:type_mismatch(#sp_simple_type{type = pos_integer}, Value)]};
        {error, Reason} ->
            {error, Reason}
    end;
do_convert_string_to_type(neg_integer, String) ->
    case do_convert_string_to_type(integer, String) of
        {ok, Value} when Value < 0 ->
            {ok, Value};
        {ok, Value} ->
            {error, [sp_error:type_mismatch(#sp_simple_type{type = neg_integer}, Value)]};
        {error, Reason} ->
            {error, Reason}
    end;
do_convert_string_to_type(Type, String) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = Type}, String)]}.

-spec try_convert_string_to_literal(Literal :: spectra:literal_value(), String :: string()) ->
    {ok, dynamic()} | {error, [spectra:error()]}.
try_convert_string_to_literal(Literal, String) when is_boolean(Literal) ->
    case convert_string_to_type(boolean, String) of
        {ok, Literal} ->
            {ok, Literal};
        {ok, _Other} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_literal{value = Literal, binary_value = atom_to_binary(Literal, utf8)},
                    String
                )
            ]};
        {error, Reason} ->
            {error, Reason}
    end;
try_convert_string_to_literal(Literal, String) when is_atom(Literal) ->
    case convert_string_to_type(atom, String) of
        {ok, Literal} ->
            {ok, Literal};
        {ok, _Other} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_literal{value = Literal, binary_value = atom_to_binary(Literal, utf8)},
                    String
                )
            ]};
        {error, Reason} ->
            {error, Reason}
    end;
try_convert_string_to_literal(Literal, String) when is_integer(Literal) ->
    case convert_string_to_type(integer, String) of
        {ok, Literal} ->
            {ok, Literal};
        {ok, _Other} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_literal{value = Literal, binary_value = integer_to_binary(Literal)},
                    String
                )
            ]};
        {error, Reason} ->
            {error, Reason}
    end;
try_convert_string_to_literal(Literal, String) ->
    {error, [
        sp_error:type_mismatch(
            #sp_literal{value = Literal, binary_value = <<>>},
            String
        )
    ]}.

union(Fun, TypeInfo, #sp_union{types = Types} = T, String, Config) ->
    case do_first(Fun, TypeInfo, Types, String, Config, []) of
        {error, UnionErrors} ->
            {error, [sp_error:no_match(T, String, UnionErrors)]};
        Result ->
            Result
    end.

do_first(_Fun, _TypeInfo, [], _String, _Config, Errors) ->
    {error, Errors};
do_first(Fun, TypeInfo, [Type | Rest], String, Config, ErrorsAcc) ->
    case Fun(TypeInfo, Type, String, Config) of
        {ok, Result} ->
            {ok, Result};
        {error, Errors} ->
            do_first(Fun, TypeInfo, Rest, String, Config, [{Type, Errors} | ErrorsAcc])
    end.

-spec convert_type_to_string(Type :: spectra:simple_types(), Data :: dynamic()) ->
    {ok, string()} | {error, [spectra:error()]}.
convert_type_to_string(integer, Data) when is_integer(Data) ->
    {ok, integer_to_list(Data)};
convert_type_to_string(integer, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = integer}, Data)]};
convert_type_to_string(float, Data) when is_float(Data) ->
    {ok, float_to_list(Data)};
convert_type_to_string(float, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = float}, Data)]};
convert_type_to_string(number, Data) when is_number(Data) ->
    if
        is_integer(Data) ->
            {ok, integer_to_list(Data)};
        is_float(Data) ->
            {ok, float_to_list(Data)}
    end;
convert_type_to_string(number, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = number}, Data)]};
convert_type_to_string(boolean, true) ->
    {ok, "true"};
convert_type_to_string(boolean, false) ->
    {ok, "false"};
convert_type_to_string(boolean, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = boolean}, Data)]};
convert_type_to_string(atom, Data) when is_atom(Data) ->
    {ok, atom_to_list(Data)};
convert_type_to_string(atom, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = atom}, Data)]};
convert_type_to_string(string, Data) when is_list(Data) ->
    list_to_charlist(string, Data);
convert_type_to_string(string, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = string}, Data)]};
convert_type_to_string(nonempty_string, Data) when is_list(Data), Data =/= [] ->
    list_to_charlist(nonempty_string, Data);
convert_type_to_string(nonempty_string, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = nonempty_string}, Data)]};
convert_type_to_string(binary, Data) when is_binary(Data) ->
    decode_utf8_binary(binary, Data);
convert_type_to_string(binary, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = binary}, Data)]};
convert_type_to_string(nonempty_binary, Data) when is_binary(Data), Data =/= <<>> ->
    decode_utf8_binary(nonempty_binary, Data);
convert_type_to_string(nonempty_binary, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = nonempty_binary}, Data)]};
convert_type_to_string(non_neg_integer, Data) when is_integer(Data), Data >= 0 ->
    {ok, integer_to_list(Data)};
convert_type_to_string(non_neg_integer, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = non_neg_integer}, Data)]};
convert_type_to_string(pos_integer, Data) when is_integer(Data), Data > 0 ->
    {ok, integer_to_list(Data)};
convert_type_to_string(pos_integer, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = pos_integer}, Data)]};
convert_type_to_string(neg_integer, Data) when is_integer(Data), Data < 0 ->
    {ok, integer_to_list(Data)};
convert_type_to_string(neg_integer, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = neg_integer}, Data)]};
convert_type_to_string(Type, Data) ->
    {error, [sp_error:type_mismatch(#sp_simple_type{type = Type}, Data)]}.

-spec decode_utf8_binary(binary | nonempty_binary, binary()) ->
    {ok, string()} | {error, [spectra:error()]}.
decode_utf8_binary(Type, Data) ->
    case unicode:characters_to_list(Data, utf8) of
        Chars when is_list(Chars) ->
            {ok, Chars};
        {error, Decoded, Rest} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_simple_type{type = Type},
                    Data,
                    #{reason => invalid_utf8, decoded => Decoded, rest => Rest}
                )
            ]};
        {incomplete, Decoded, Rest} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_simple_type{type = Type},
                    Data,
                    #{reason => incomplete_utf8, decoded => Decoded, rest => Rest}
                )
            ]}
    end.

-spec encode_utf8_binary(binary | nonempty_binary, string()) ->
    {ok, binary()} | {error, [spectra:error()]}.
encode_utf8_binary(Type, String) ->
    case unicode:characters_to_binary(String, utf8) of
        Bin when is_binary(Bin) ->
            {ok, Bin};
        {error, Encoded, Rest} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_simple_type{type = Type},
                    String,
                    #{reason => invalid_codepoints, encoded => Encoded, rest => Rest}
                )
            ]};
        {incomplete, Encoded, Rest} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_simple_type{type = Type},
                    String,
                    #{reason => incomplete_codepoints, encoded => Encoded, rest => Rest}
                )
            ]}
    end.

-spec list_to_charlist(string | nonempty_string, list()) ->
    {ok, string()} | {error, [spectra:error()]}.
list_to_charlist(Type, Data) ->
    case unicode:characters_to_list(Data) of
        Chars when is_list(Chars) ->
            {ok, Chars};
        {error, Decoded, Rest} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_simple_type{type = Type},
                    Data,
                    #{reason => invalid_unicode, decoded => Decoded, rest => Rest}
                )
            ]};
        {incomplete, Decoded, Rest} ->
            {error, [
                sp_error:type_mismatch(
                    #sp_simple_type{type = Type},
                    Data,
                    #{reason => incomplete_unicode, decoded => Decoded, rest => Rest}
                )
            ]}
    end.

-spec try_convert_literal_to_string(Literal :: spectra:literal_value(), Data :: dynamic()) ->
    {ok, string()} | {error, [spectra:error()]}.
try_convert_literal_to_string(Literal, Literal) when is_atom(Literal) ->
    {ok, atom_to_list(Literal)};
try_convert_literal_to_string(Literal, Literal) when is_integer(Literal) ->
    {ok, integer_to_list(Literal)};
try_convert_literal_to_string(Literal, Literal) when is_boolean(Literal) ->
    if
        Literal ->
            {ok, "true"};
        true ->
            {ok, "false"}
    end;
try_convert_literal_to_string(Literal, Data) ->
    {error, [
        sp_error:type_mismatch(
            #sp_literal{value = Literal, binary_value = <<>>},
            Data
        )
    ]}.