%%% -*- erlang-indent-level:4; indent-tabs-mode: nil -*-
%%%-------------------------------------------------------------------
%%% @copyright (C) 2025, QPQ AG
%%% @copyright (C) 2017, Aeternity Anstalt
%%% @doc Bootstrapping and querying the Gajumaru environment
%%%
%%% @end
%%%-------------------------------------------------------------------
-module(gmconfig).

-export([get_env/2, get_env/3]).

-export([user_config/0]).             % returns current user config
-export([load_main_config_schema/0,
         load_system_defaults/0]).
-export([load_user_config/0,
         load_user_config/1]).
-export([schema/0,
         schema/1,
         schema/2]).
-export([load_schema/0]).              % load_user_config() ensures schema is loaded
-export([schema_default/1, schema_default/2]).
-export([schema_keys/0, schema_keys/1]).
-export([config_value/4]).
-export([find_config/1, find_config/2,    %% -> {ok, Value} | undefined
         get_config/1, get_config/2       %% -> Value   (or exception)
        ]).
-export([merge_config_maps/2]).
-export([nested_map_get/2]).
-export([load_config_file/1]).  % apply system-/network-specific defaults
-export([search_for_config_file/2]).
-export([apply_os_env/0,
         apply_os_env/3]).
-export([process_plain_args/0]).
-export([data_dir/1]).
-export([check_config/1]).

-export([update_config/1,
         update_config/2,
         update_config/3,
         silent_update_config/1,
         delete_config_value/1,
         suggest_config/2,
         set_config_value/2]).  %% (Path, Value)

-export([export_config/0]).

-export([ gmconfig_env/0
        , gmconfig_env/1
        , gmconfig_env/2
        , set_gmconfig_env/1
        , default_gmconfig_env/0
        ]).

-ifdef(TEST).
-export([mock_config/0,
         mock_config/1,
         mock_system_defaults/0,
         mock_system_defaults/1,
         ensure_schema_loaded/0,
         unmock_schema/0,
         unmock_config/0]).
-endif.

-include_lib("kernel/include/logger.hrl").

-type extension() :: string().   %% file extension (without leading dot)

-type decoder_return() :: config_tree()
                        | {ok, config_tree()}
                        | {error, any()}.
-type decoder_fun() :: fun( (binary()) -> decoder_return() ).

-type gmconfig() :: #{ os_env_prefix => string()
                     , config_file_basename => string() | 'undefined'
                     , config_file_os_env => string() | 'undefined'
                     , config_file_search_path => [string() | fun(() -> string())]
                     , config_plain_args => string() | 'undefined'
                     , system_suffix  => string()
                     , config_formats => #{ extension() => decoder_fun() }
                     , schema => string() | map() | fun(() -> map())}.

-type basic_type() :: number() | binary() | boolean().
-type basic_or_list()  :: basic_type() | [basic_type()].
-type config_tree() :: [{binary(), config_tree() | basic_or_list()}].

%% -type env_key() :: atom() | list().
-type config_key() :: binary() | [binary()].

-type find_opts() :: [user_config | schema_default | {env, atom(), atom()} | {value, any()}].

-export_type([ gmconfig/0
             , find_opts/0 ]).

-ifdef(TEST).

mock_config() ->
    mock_config(#{}).

mock_config(Cfg) ->
    ensure_schema_loaded(),
    store(Cfg, _Notify = false, _Mode = silent).

unmock_config() ->
    gmconfig_schema_utils:clear(),
    ok.

unmock_schema() ->
    gmconfig_schema_utils:clear(),
    ok.

mock_system_defaults() ->
    mock_config(),
    load_system_defaults(silent).

mock_system_defaults(Config) ->
    ensure_schema_loaded(),
    load_system_defaults(silent),
    mock_config(Config).

-endif.

-spec set_gmconfig_env(gmconfig()) -> ok.
set_gmconfig_env(Env0) when is_map(Env0) ->
    Env = maps:merge(default_gmconfig_env(), Env0),
    persistent_term:put({?MODULE, gmconfig_env}, Env).

-spec gmconfig_env() -> gmconfig().
gmconfig_env() ->
    persistent_term:get({?MODULE, gmconfig_env}, default_gmconfig_env()).

-spec gmconfig_env(atom()) -> any().
gmconfig_env(Key) ->
    gmconfig_env(Key, undefined).

gmconfig_env(Key, Default) ->
    maps:get(Key, gmconfig_env(), Default).

search_path() -> search_path(config_file).

search_path(Kind) ->
    Key = case Kind of
              config_file -> config_file_search_path;
              system_defaults -> system_defaults_search_path
          end,
    case gmconfig_env(Key, undefined) of
        undefined -> [];
        Path0 when is_list(Path0) ->
            lists:map(
              fun(F) when is_function(F, 0) ->
                      F();
                 (D) when is_list(D) ->
                      D
              end, Path0)
    end.

default_gmconfig_env() ->
    #{ os_env_prefix => "GM"
     , config_file_basename => "gmconfig"
     , config_file_os_env => undefined
     , config_file_search_path => ["."]
     , config_formats => #{ "json"  => fun json_decode/1
                          , "eterm" => fun eterm_consult/1 }
     , config_plain_args => undefined
     , system_defaults_search_path => [fun setup:data_dir/0]
     , system_suffix => "" }.

%% This function is similar to application:get_env/2, except
%% 1. It uses the setup:get_env/2 function, which supports a number
%%    of useful variable expansions (see the setup documentation)
%% 2. It supports a hierarchical key format, [A,B,...], where each
%%    part of the key represents a level in a tree structure.
%% Example:
%% if get_env(A, a) returns {ok, {a, [{1, foo}, {2, bar}]}}, or
%% {ok, [{a, [{1, foo}, {2, bar}]}]}, then
%% get_env(A, [a,1]) will return {ok, foo}
-spec get_env(atom(), atom() | list()) -> undefined | {ok, any()}.
get_env(App, [H|T]) ->
    case setup:get_env(App, H) of
        {ok, V} ->
            get_env_l(T, V);
        undefined ->
            undefined
    end;
get_env(App, K) when is_atom(K) ->
    setup:get_env(App, K).

get_env(App, K, Default) ->
    case get_env(App, K) of
        {ok, V}   -> V;
        undefined -> Default
    end.

get_env_l([], V) ->
    {ok, V};
get_env_l([H|T], [_|_] = L) ->
    case lists:keyfind(H, 1, L) of
        {_, V} ->
            get_env_l(T, V);
        false ->
            undefined
    end;
get_env_l(_, _) ->
    undefined.

-spec user_config() -> config_tree().
user_config() ->
    pt_get_config().

config_value(CfgKey, App, Env, Default) ->
    {ok, Value} =find_config(CfgKey, [ user_config
                                     , {env, App, Env}
                                     , schema_default
                                     , {value, Default} ]),
    Value.

%%% ====================================================================================
%%% Config lookup API
%%%
%%% These are the preferred functions for config data lookup

get_config(CfgKey) ->
    get_config(CfgKey, [user_config, schema_default]).

get_config(CfgKey, Path) ->
    case find_config(CfgKey, Path) of
        {ok, Value} ->
            Value;
        undefined ->
            error(expected_value, [CfgKey, Path])
    end.

find_config(CfgKey) ->
    find_config(CfgKey, [user_config, schema_default]).

find_config(CfgKey, [H|T]) ->
    case find_config_(CfgKey, H) of
        undefined -> find_config(CfgKey, T);
        {ok,_} = Ok -> Ok
    end;
find_config(_, []) ->
    undefined.

find_config_(K, user_config       ) -> user_map(K);
find_config_(_, {env, App, EnvKey}) -> get_env(App, EnvKey);
find_config_(K, schema_default    ) -> schema_default(K);
find_config_(_, {value, V}        ) -> {ok, V}.


%%% ====================================================================================
%%% Merging config maps
%%%
%%% This function implements a deep map merge, ensuring that sub-maps also get merged.
-spec merge_config_maps(map(), map()) -> map().
merge_config_maps(A, B) ->
    {A1, B1} =
        maps:fold(
          fun(K, V, {Ca, Cb}) when is_map(V), is_map(map_get(K, Cb)) ->
                  {Ca#{K := merge_config_maps(V, map_get(K, Cb))}, maps:remove(K, Cb)};
             (_, _, Acc) ->
                  Acc
          end, {A, B}, A),
    maps:merge(A1, B1).


%% The user_map() functions are equivalent to user_config(), but
%% operate on a tree of maps rather than a tree of {K,V} tuples.
%% Actually, the user_map() data is the original validated object,
%% which is then transformed to the Key-Value tree used in user_config().
-spec user_map() -> map().
user_map() ->
    pt_get_config().

-spec user_map([any()] | any()) -> {ok, any()} | undefined.
user_map(Key) when is_list(Key) ->
    M = user_map(),
    case maps:find(Key, M) of
        {ok, _} = Ok ->
            Ok;
        error ->
            nested_map_get(Key, M)
    end;
user_map(Key) ->
    case maps:find(Key, user_map()) of
        {ok, _} = Ok -> Ok;
        error        -> undefined
    end.

nested_map_get([], V) ->
    {ok, V};
nested_map_get([H|T], M) when is_map(M) ->
    case maps:find(H, M) of
        {ok, M1} when is_map(M1); is_list(M1) ->
            nested_map_get(T, M1);
        {ok, V} when T == [] ->
            {ok, V};
        _ ->
            undefined
    end;
nested_map_get([H|T], L) when is_list(L) ->
    case lists_map_key_find(H, L) of
        {ok, V} when is_map(V); is_list(V) ->
            nested_map_get(T, V);
        {ok, V} when T == [] ->
            {ok, V};
        error ->
            undefined
    end.

lists_map_key_find({K,V,Then} = Pat, [#{} = H|T]) ->
    case maps:find(K, H) of
        {ok, V} ->
            maps:find(Then, H);
        {ok, _} ->
            lists_map_key_find(Pat, T);
        error ->
            lists_map_key_find(Pat, T)
    end;
lists_map_key_find(K, [#{} = H|T]) ->
    case maps:find(K, H) of
        {ok, _} = Ok ->
            Ok;
        error ->
            lists_map_key_find(K, T)
    end;
lists_map_key_find(K, [{K, V}|_]) ->
    {ok, V};
lists_map_key_find(_, []) ->
    error.

schema() ->
    case pt_get_schema(undefined) of
        undefined ->
            load_schema(),
            pt_get_schema();
        S ->
            S
    end.

pt_get_schema() ->
    gmconfig_schema_utils:get_schema().

pt_get_schema(Default) ->
    gmconfig_schema_utils:get_schema(Default).

pt_set_schema(Schema) ->
    gmconfig_schema_utils:set_schema(Schema).

pt_get_config() ->
    gmconfig_schema_utils:get_config().

pt_set_config(Config) ->
    gmconfig_schema_utils:set_config(Config).

schema(Key) ->
    gmconfig_schema_utils:schema(Key).

schema(Key, Schema) ->
    gmconfig_schema_utils:schema(Key, Schema).

schema_keys() ->
    schema_keys([]).

schema_keys(Path) ->
    case schema(Path) of
        undefined ->
            undefined;
        {ok, Map} ->
            just_schema_keys(Map)
    end.

just_schema_keys(#{<<"properties">> := Ps}) ->
    maps:fold(fun(K, V, Acc) ->
                      Acc#{K => just_schema_keys(V)}
              end, #{}, Ps);
just_schema_keys(#{<<"patternProperties">> := Ps}) ->
    maps:fold(fun(K, V, Acc) ->
                      Acc#{{'$pat', K} => just_schema_keys(V)}
              end, #{}, Ps);
just_schema_keys(#{<<"type">> := <<"array">>, <<"items">> := Items}) ->
    case Items of
        #{<<"type">> := <<"object">>} ->
            [just_schema_keys(Items)];
        #{<<"type">> := T} ->
            [binary_to_atom(T, utf8)];
        #{<<"pattern">> := _} ->
            [string]
    end;
just_schema_keys(#{<<"oneOf">> := List}) ->
    #{<<"oneOf">> => lists:foldr(
                       fun(Alt, Acc) ->
                               case just_schema_keys(Alt) of
                                   [] ->
                                       [maps:fold(
                                          fun(K, #{<<"type">> := T}, Acc1) ->
                                                  Acc1#{K => binary_to_atom(T, utf8)};
                                             (_, _, Acc1) ->
                                                  Acc1
                                          end, #{}, Alt) | Acc];
                                   Other ->
                                       [Other|Acc]
                               end
                       end, [], List)};
just_schema_keys(#{<<"type">> := T}) ->
    binary_to_atom(T, utf8);
just_schema_keys(#{properties := Ps}) ->
    maps:fold(fun(K, V, Acc) ->
                      Acc#{K => just_schema_keys(V)}
              end, #{}, Ps);
just_schema_keys(#{patternProperties := Ps}) ->
    maps:fold(fun(K, V, Acc) ->
                      Acc#{{'$pat', K} => just_schema_keys(V)}
              end, #{}, Ps);
just_schema_keys(#{type := array, items := Items}) ->
    case Items of
        #{type := object} ->
            [just_schema_keys(Items)];
        #{type := T} ->
            [T];
        #{pattern := _} ->
            [string]
    end;
just_schema_keys(#{oneOf := List}) ->
    #{oneOf => lists:foldr(
                       fun(Alt, Acc) ->
                               case just_schema_keys(Alt) of
                                   [] ->
                                       [maps:fold(
                                          fun(K, #{type := T}, Acc1) ->
                                                  Acc1#{K => T};
                                             (_, _, Acc1) ->
                                                  Acc1
                                          end, #{}, Alt) | Acc];
                                   Other ->
                                       [Other|Acc]
                               end
                       end, [], List)};
just_schema_keys(#{type := T}) ->
    T;
just_schema_keys(_) ->
    [].

schema_default(Path) when is_list(Path) ->
    schema_default(Path, schema()).

schema_default(Path, Schema) ->
    case schema(Path, Schema) of
        undefined -> undefined;
        {ok, Tree} ->
            case schema_default_(Tree) of
                undefined -> undefined;
                Res ->
                    {ok, Res}
            end
      end.

schema_default_(#{<<"type">> := <<"object">>, <<"properties">> := Props}) ->
    maps:map(fun(_, #{<<"type">> := <<"object">>} = PP) ->
                     schema_default_(PP);
                (_, #{<<"type">> := <<"array">>, <<"default">> := Def}) ->
                     Def;
                (_, #{<<"type">> := <<"array">>, <<"items">> := Items}) ->
                     [schema_default_(Items)];
                (_, #{<<"default">> := Def}) -> Def;
                (_, _) -> undefined
             end, Props);
schema_default_(#{<<"type">> := <<"array">>, <<"default">> := Def}) ->
    Def;
schema_default_(#{<<"type">> := <<"array">>, <<"items">> := Items}) ->
    [schema_default_(Items)];
schema_default_(#{<<"default">> := Def}) ->
    Def;
schema_default_(#{type := <<"object">>, properties := Props}) ->
    maps:map(fun(_, #{<<"type">> := <<"object">>} = PP) ->
                     schema_default_(PP);
                (_, #{type := array, default := Def}) ->
                     Def;
                (_, #{type := array, items := Items}) ->
                     [schema_default_(Items)];
                (_, #{default := Def}) -> Def;
                (_, _) -> undefined
             end, Props);
schema_default_(#{type := array, default := Def}) ->
    Def;
schema_default_(#{type := array, items := Items}) ->
    [schema_default_(Items)];
schema_default_(#{default := Def}) ->
    Def;
schema_default_(_) ->
    undefined.

load_user_config() ->
    load_user_config(silent).

load_user_config(Mode) when Mode =:= check; Mode =:= silent; Mode =:= report ->
    case config_file() of
        undefined ->
            info_msg(Mode, "No config file specified; using default settings~n", []),
            ok;
        F ->
            info_msg(Mode, "Reading config file ~s~n", [F]),
            do_load_user_config(F, store, Mode)
    end.

load_config_file(File) ->
    load_config_file(File, report).

load_config_file(File, Mode) when Mode =:= check;
                                  Mode =:= silent;
                                  Mode =:= report ->
    do_load_user_config(File, store, Mode).

apply_os_env() ->
    Pfx = os_env_prefix(),
    ConfigMap = pt_get_config(),
    case apply_os_env(Pfx, schema(), ConfigMap) of
        NewConfig when is_map(NewConfig) ->
            pt_set_config(NewConfig),
            NewConfig;
        Other ->
            Other
    end.

os_env_prefix() ->
    gmconfig_env(os_env_prefix, "GM").

%% Plugin API version, using plugin schema and config.
%% The plugin API might decide to publish a specific event...
apply_os_env(Pfx, Schema, ConfigMap) ->
    %% We sort on variable names to allow specific values to override object
    %% definitions at a higher level (e.g. GM__MEMPOOL followed by GM__MEMPOOL__TX_TTL)
    %% Note that all schema name parts are converted to uppercase.
    try
    Names = lists:keysort(1, schema_key_names(Pfx, Schema)),
    error_logger:info_msg("OS env config: ~p~n", [Names]),
    Map = lists:foldl(
            fun({_Name, Key, Value}, Acc) ->
                    Value1 = coerce_type(Key, Value, Schema),
                    update_map(to_map(Key, Value1), Acc)
            end, #{}, Names),
    error_logger:info_msg("Map for OS env config: ~p~n", [Map]),
    if map_size(Map) > 0 ->
            update_config_(Map, ConfigMap, Schema, report);
       true ->
            no_change
    end
    catch
        error:E:ST ->
            error_logger:info_msg("CAUGHT error:~p / ~p~n", [E, ST]),
            error(E)
    end.

process_plain_args() ->
    case gmconfig_env(config_plain_args, undefined) of
        undefined ->
            ok;
        Str ->
            PlainArgs = init:get_plain_arguments(),
            Schema = schema(),
            Map = process_plain_args_(PlainArgs, Str, schema(), #{}),
            ?LOG_INFO("Map from plain args: ~p", [Map]),
            if map_size(Map) > 0 ->
                    update_config_(Map, pt_get_config(), Schema, report);
               true ->
                    no_change
            end
    end.

process_plain_args_([Tag, K, V | Rest], Tag, Schema, Map) ->
    Path = plain_path_arg(K),
    Value = coerce_type(Path, V, Schema),
    Map1 = update_map(to_map(Path, Value), Map),
    process_plain_args_(Rest, Tag, Schema, Map1);
process_plain_args_([_ | T], Tag, Schema, Map) ->
    process_plain_args_(T, Tag, Schema, Map);
process_plain_args_([], _, _, Map) ->
    Map.

plain_path_arg(Str) ->
    re:split(Str, <<"__">>, [{return, binary}]).

to_map(K, V) ->
    to_map(K, V, #{}).

to_map([K], Val, M) ->
    M#{K => Val};
to_map([H|T], Val, M) ->
    SubMap = maps:get(H, M, #{}),
    M#{H => to_map(T, Val, SubMap)}.

coerce_type(Key, Value, Schema) ->
    case schema(Key, Schema) of
        {ok, #{<<"type">> := Type}} ->
            case Type of
                <<"integer">> -> to_integer(Value);
                <<"string">>  -> to_string(Value);
                <<"boolean">> -> to_bool(Value);
                <<"array">>   -> json:decode(list_to_binary(Value));
                <<"object">>  -> json:decode(list_to_binary(Value))
            end;
        _ ->
            error({unknown_key, Key})
    end.

to_integer(I) when is_integer(I) -> I;
to_integer(L) when is_list(L)    -> list_to_integer(L);
to_integer(B) when is_binary(B)  -> binary_to_integer(B).

to_string(L) when is_list(L)   -> list_to_binary(L);
to_string(B) when is_binary(B) -> B.

to_bool("true")  -> true;
to_bool("false") -> false;
to_bool(B) when is_boolean(B) ->
    B;
to_bool(Other) ->
    error({expected_boolean, Other}).

schema_key_names(Prefix, Schema) ->
    case Schema of
        #{<<"$schema">> := _, <<"properties">> := Props} ->
            schema_key_names(Prefix, [], Props, []);
        _ ->
            []
    end.

schema_key_names(NamePfx, KeyPfx, Map, Acc0) when is_map(Map) ->
    maps:fold(
      fun(SubKey, SubMap, Acc) ->
              NamePfx1 = NamePfx ++ "__" ++ string:to_upper(binary_to_list(SubKey)),
              KeyPfx1 = KeyPfx ++ [SubKey],
              EnvKey = unhyphenate(NamePfx1),
              Acc1 = case os:getenv(EnvKey) of
                         false -> Acc;
                         Value ->
                             [{EnvKey, KeyPfx1, Value} | Acc]
                     end,
              case maps:find(<<"properties">>, SubMap) of
                  error ->
                      Acc1;
                  {ok, Props} ->
                      schema_key_names(NamePfx1, KeyPfx1, Props, Acc1)
              end
      end, Acc0, Map).

%% Unfortunately, the config schema contains some names with hyphens in them.
%% Since hyphens aren't allowed in OS environment names, we replace them with underscores.
%% This should be safe, since we DO NOT stupidly have names that differ only on '-' v '_'.
unhyphenate(Str) ->
    re:replace(Str, <<"\\-">>, <<"_">>, [global, {return, list}]).

check_config(F) ->
    do_load_user_config(F, check, check).

data_dir(Name) when is_atom(Name) ->
    filename:join([setup:data_dir(), Name]).

config_file() ->
    case command_line_config_file() of
        undefined ->
            default_config_file();
        F -> F
    end.

command_line_config_file() ->
    case init:get_argument('-config') of
        {ok, [[F]]} -> F;
        _ -> undefined
    end.

default_config_file() ->
    case gmconfig_env(config_file_os_env, undefined) of
        undefined ->
            search_default_config();
        E ->
            case os:getenv(E) of
                false -> search_default_config();
                F     -> F
            end
    end.

search_default_config() ->
    case gmconfig_env(config_file_basename, undefined) of
        undefined -> undefined;
        Basename ->
            Dirs = search_path(),
            SystemSuffix = get_system_suffix(),
            ExtPattern = extension_pattern(),
            Fname = Basename ++ SystemSuffix ++ ExtPattern,
            search_for_config_file(Dirs, Fname)
    end.

config_formats() ->
    gmconfig_env(config_formats).

extension_pattern() ->
    Exts = maps:keys(config_formats()),
    lists:flatten([".{", intersperse(Exts),"}"]).

intersperse([H|T]) ->
    [H | [[",", X] || X <- T]].

search_for_config_file(Dirs, FileWildcard) ->
    lists:foldl(
      fun(D0, undefined) ->
              D = to_list_string(D0),
              error_logger:info_msg("Searching for config file ~s "
                                    "in directory ~s~n", [FileWildcard, D]),
              case filelib:wildcard(FileWildcard, D) of
                  [] -> undefined;
                  [F|_] -> filename:join(D, F)
              end;
         (_, Acc) -> Acc
      end, undefined, Dirs).

to_list_string(S) when is_binary(S) ->
    binary_to_list(S);
to_list_string(S) when is_list(S) ->
    binary_to_list(iolist_to_binary(S)).

do_load_user_config(F, Action, Mode) ->
    {Ext, Decoder} = pick_decoder(F),
    case Action of
        store -> store(read_file(F, Ext, Decoder, Mode), Mode);
        check -> check_config_(catch read_file(F, Ext, Decoder, Mode))
    end.

pick_decoder(F) ->
    "." ++ Ext = filename:extension(F),
    {Ext, maps:get(Ext, config_formats())}.

store(Vars, Mode) when is_map(Vars) ->
    case pt_get_config() of
        Map when map_size(Map) == 0 ->
            check_validation([validate_(Vars)],
                             [Vars], set_config_value, report),
            pt_set_config(Vars);
        Map ->
            ?LOG_DEBUG("Existing config, updating ...", []),
            update_config(Vars, Map, Mode)
    end;
store([Vars], Mode) when is_map(Vars) ->
    store(Vars, Mode).

check_config_({yamerl_exception, _StackTrace} = Error) ->
    {error, Error};
check_config_({'EXIT', Reason}) ->
    ShortError = pp_error(Reason),
    {error, ShortError};
check_config_([Vars]) ->
    {ok, {Vars, to_tree(Vars)}}.

pp_error({validation_failed, _}) ->
    validation_failed;
pp_error(Other) ->
    Other.

pp_error_({error, {schema_file_not_found, Schema}}, Mode) ->
    error_format("Schema not found : ~s", [Schema], Mode);
pp_error_({error, [{data_invalid, _Schema, Type, Value, Pos}]}, Mode) ->
    PosStr = pp_pos(Pos),
    ValStr = pp_val(Value),
    TypeStr = pp_type(Type),
    case Mode of
        check ->
            io:format("Validation failed~n"
                      "Position: ~s~n"
                      "Value   : ~s~n"
                      "Reason  : ~s~n",
                      [PosStr, ValStr, TypeStr]);
        report ->
            error_format("Validation failed, Pos: ~s~n"
                         "Value: ~s~n"
                         "Reason: ~s", [PosStr, ValStr, TypeStr], Mode)
    end;
pp_error_({error, [{schema_invalid, Section, Description}]}, Mode) ->
    SchemaStr = schema_string(Section, Mode),
    error_format("Reading schema failed~n"
                 "Section: ~n~s~n"
                 "Reason: ~p~n", [SchemaStr, Description], Mode).

silent_as_report(silent) -> report;
silent_as_report(Mode  ) -> Mode.

schema_string(Schema, Mode) ->
    JSONSchema = json_encode(Schema),
    case Mode of
        check  -> json:format(JSONSchema, #{indent => 2});
        report -> JSONSchema
    end.

json_encode(J) ->
    iolist_to_binary(json:encode(J)).

error_format(Fmt, Args, check) ->
    io:format(Fmt, Args);
error_format(Fmt, Args, report) ->
    Str = io_lib:format(Fmt, Args),
    Parts = re:split(Str, <<"\n">>),
    Out = iolist_to_binary(
            [hd(Parts) |
             [[" | ", P] || P <- tl(Parts)]]),
    Out = re:replace(Str, <<"\n">>, <<" | ">>, [global, {return, binary}]),
    ?LOG_ERROR("~s", [Out]).

pp_pos([H | T]) ->
    [to_string(H) | [pp_pos_(X) || X <- T]].

pp_pos_(I) when is_integer(I) -> ["[", integer_to_list(I), "]"];
pp_pos_(S) when is_binary(S)  -> ["/", S].

pp_val(I) when is_integer(I) -> integer_to_list(I);
pp_val(S) when is_binary(S)  -> ["\"", S, "\""];
pp_val(X) ->
    try schema_string(X, report)
    catch
        error:_ ->
            io_lib:fwrite("~w", [X])
    end.

pp_type(data_invalid)     -> "Data invalid";
pp_type(missing_id_field) -> "Missing ID field";
pp_type(missing_required_property) -> "Missing required property";
pp_type(no_match  )       -> "No match";
pp_type(no_extra_properties_allowed) -> "No extra properties allowed";
pp_type(no_extra_items_allowed)      -> "No extra items allowed";
pp_type(not_allowed)      -> "Not allowed";
pp_type(not_unique)       -> "Not unique";
pp_type(not_in_enum)      -> "Not in enum";
pp_type(not_in_range)     -> "Not in range";
pp_type(not_divisible)    -> "Not divisible";
pp_type(wrong_type)       -> "Wrong type";
pp_type(wrong_size)       -> "Wrong size";
pp_type(wrong_length)     -> "Wrong length";
pp_type(wrong_format)     -> "Wrong format";
pp_type(too_many_properties)   -> "Too many properties";
pp_type(too_few_properties)    -> "Too few properties";
pp_type(all_schemas_not_valid) -> "The 'allOf' requirement is not upheld";
pp_type(any_schemas_not_valid) -> "The 'anyOf' requirement is not upheld";
pp_type(not_multiple_of)       -> "Not an instance of 'multipleOf'";
pp_type(not_one_schema_valid)  -> "The 'oneOf' requirement is not upheld";
pp_type(not_schema_valid)      -> "The 'not' requirement is not upheld";
pp_type(wrong_not_schema)      -> "Wrong not schema";
pp_type(external)              -> "External";
pp_type(Other)            ->  io_lib:fwrite("~w", [Other]).

to_tree(Vars) ->
    to_tree_(expand_maps(Vars)).

expand_maps(M) when is_map(M) ->
    [{K, expand_maps(V)} || {K, V} <- maps:to_list(M)];
expand_maps(L) when is_list(L) ->
    [expand_maps(E) || E <- L];
expand_maps(E) ->
    E.

to_tree_(L) when is_list(L) ->
    lists:flatten([to_tree_(E) || E <- L]);
to_tree_({K, V}) ->
    {K, to_tree_(V)};
to_tree_(E) ->
    E.

silent_update_config(Map) ->
    update_config(Map, _Notify = false, silent).

update_config(Map) when is_map(Map) ->
    update_config(Map, report).

update_config(Map, Mode) when is_map(Map) ->
    ConfigMap = pt_get_config(),
    update_config(Map, ConfigMap, Mode).

update_config(Map, ConfigMap, Mode) ->
    Schema = pt_get_schema(),
    ConfigMap1 = update_config_(Map, ConfigMap, Schema, Mode),
    ?LOG_DEBUG("New config: ~p", [ConfigMap1]),
    pt_set_config(ConfigMap1),
    ok.

export_config() ->
    Config = pt_get_config(),
    JSON = json:format(Config, #{indent => 2}),
    TS = calendar:system_time_to_rfc3339(erlang:system_time(second)),
    File = filename:join(setup:log_dir(), "user_config-" ++ TS ++ ".json"),
    file:write_file(File, JSON).

-spec delete_config_value(config_key()) -> boolean().
delete_config_value(Key) when is_binary(Key) ->
    delete_config_value([Key]);
delete_config_value(Path) when is_list(Path) ->
    Config = pt_get_config(),
    case delete_(Path, Config) of
        Config1 when Config1 =/= Config ->
            pt_set_config(Config1),
            true;
        _ ->
            false
    end.

delete_([H], Config) when is_map_key(H, Config) ->
    maps:remove(H, Config);
delete_([H|T], Map) when T =/= [], is_map_key(H, Map) ->
    Map#{H := delete_(T, maps:get(H, Map))};
delete_(_, C) ->
    C.

set_config_value(Path, Value) ->
    ConfigMap = pt_get_config(),
    NewConfig = set_config_value(Path, ConfigMap, Value),
    check_validation([validate_(NewConfig)],
                     [NewConfig], set_config_value, report),
    pt_set_config(NewConfig).

set_config_value([K], Map, Value) when is_map(Map) ->
    Map#{K => Value};
set_config_value([H|T], Map, Value) when is_map(Map) ->
    case maps:find(H, Map) of
        {ok, Sub} when is_map(Sub) ->
            Map#{H := set_config_value(T, Sub, Value)};
        _ ->
            Map#{H => set_config_value(T, #{}, Value)}
    end.

%% Checks if a given config key (list of binary keys corresponding to the GM
%% config schema) is already configured. If not, the suggested value is used.
suggest_config(Key, Value) ->
    case find_config(Key, [user_config]) of
        {ok, _} ->
            {error, already_configured};
        undefined ->
            Map = kv_to_config_map(Key, Value),
            update_config(Map),
            ok
    end.

kv_to_config_map([H], V) ->
    #{H => V};
kv_to_config_map([H|T], V) ->
    #{H => kv_to_config_map(T, V)}.

update_config_(Map, _ConfigMap, Schema, Mode) when Mode =:= check;
                                                  Mode =:= silent;
                                                  Mode =:= report ->
    NewConfig = gmconfig_schema_utils:update_config(Map),
    %% NewConfig = update_map(Map, ConfigMap),
    ?LOG_DEBUG("NewConfig = ~p", [NewConfig]),
    %% Note: We must validate the *resulting* config, since some validation
    %% steps will require the full structure (e.g. multiple required fields in
    %% the original config, which should not have to be included in the update)
    check_validation([validate_(NewConfig, Schema)],
                     [NewConfig], update_config, Mode),
    NewConfig.


update_map(With, Map) when is_map(With), is_map(Map) ->
    maps:fold(
      fun(K, V, Acc) ->
              case maps:find(K, Acc) of
                  {ok, Submap} when is_map(Submap) ->
                      Acc#{K => update_map(V, Submap)};
                  {ok, _} ->
                      Acc#{K => V};
                  error ->
                      Acc#{K => V}
              end
      end, Map, With).

read_file(F, Type, Decoder, Mode) ->
    case setup_file:read_file(F) of
        {ok, Bin} ->
            validate(
              try_decode_bin(Bin, Decoder, Type, Mode),
              F, Mode);
        {error, Reason} ->
            error_msg(Mode, "Read error ~s - ~p", [F, Reason]),
            error({read_error, F, Reason})
    end.

json_decode(Str) when is_list(Str) ->
    json:decode(iolist_to_binary(Str));
json_decode(Bin) when is_binary(Bin) ->
    json:decode(Bin).

eterm_consult(Bin) ->
    case setup_file:consult_binary(Bin) of
        {ok, [Map]} when is_map(Map) ->
            {ok, normalize_config(Map)};
        {ok, Other} ->
            error({unknown_data, Other});
        {error, _} = Error ->
            Error
    end.

normalize_config(Map) when is_map(Map) ->
    try
        json:decode(iolist_to_binary(json:encode(Map)))
    catch
        error:E ->
            error({cannot_normalize, E, Map})
    end.

try_decode_bin(Bin, Decoder, Fmt, Mode) ->
    try decode_bin(Bin, Decoder)
    catch
        error:E:T ->
            error_msg(Mode, "CAUGHT for ~p: ~p / ~p", [Fmt, E, T]),
            error(E)
    end.

decode_bin(Str, Decoder) when is_list(Str) ->
    decode_bin(iolist_to_binary(Str), Decoder);
decode_bin(Bin, Decoder) when is_binary(Bin), is_function(Decoder, 1) ->
    case Decoder(Bin) of
        {ok, Map} when is_map(Map) ->
            Map;
        Map when is_map(Map) ->
            Map;
        {error, E} ->
            error(E);
        Other ->
            error({bad_decoder_return, Other})
    end.

validate(JSON, F, Mode) when is_map(JSON) ->
    check_validation([validate_(JSON)], JSON, F, Mode).

vinfo(Mode, Res, F) ->
    case Res of
        {ok, _} ->
            info_report(Mode, [{validation, F},
                               {result, Res}]);
        {error, Errors} ->
            Mode1 = silent_as_report(Mode),
            [pp_error_(E, Mode1) || E <- Errors],
            ok
    end.

info_report(report, Info) ->
    error_logger:info_report(Info);
info_report(_, _) ->
    ok.

info_msg(report, Fmt, Args) ->
    error_logger:info_msg(Fmt, Args);
info_msg(_, _,_ ) ->
    ok.

error_msg(report, Fmt, Args) ->
    error_logger:error_msg(Fmt, Args);
error_msg(_, _, _) ->
    ok.

check_validation(Res, _JSON, F, Mode) ->
    case lists:foldr(
           fun({ok, M}, {Ok,Err}) when is_map(M) ->
                   {[M|Ok], Err};
              (Other, {Ok,Err}) ->
                   {Ok, [Other|Err]}
           end, {[], []}, Res) of
        {Ok, []} ->
            vinfo(Mode, {ok, Ok}, F),
            Ok;
        {_, Errors} ->
            vinfo(Mode, {error, Errors}, F),
            erlang:error(validation_failed)
    end.

validate_(JSON) ->
    Schema = ensure_schema_loaded(),
    validate_(JSON, Schema).

validate_(JSON, Schema) ->
    _ = gmconfig_schema_utils:valid(JSON, Schema),
    {ok, JSON}.

load_main_config_schema() ->
    _ = load_schema(),
    ?LOG_INFO("Loaded config schema", []),
    ok.

load_system_defaults() ->
    load_system_defaults(report).

load_system_defaults(Mode) ->
    case gmconfig_env(config_file_basename, undefined) of
        undefined ->
            ok;
        Basename ->
            SystemSuffix = get_system_suffix(),
            Fname = Basename ++ "_defaults" ++ SystemSuffix ++ ".{yaml,json}",
            Path = search_path(system_defaults),
            case search_for_config_file(Path, Fname) of
                undefined ->
                    ok;
                ConfigFile ->
                    ?LOG_DEBUG("Loading system defaults from ~s", [ConfigFile]),
                    load_config_file(ConfigFile, Mode)
            end
    end.

get_system_suffix() ->
    case init:get_argument('-system') of
        error ->
            Pfx = os_env_prefix(),
            case os:getenv(Pfx ++ "_SYSTEM") of
                false ->
                    "";
                Suffix ->
                    "_" ++ Suffix
            end;
        {ok, [[Suffix]]} ->
            "_" ++ Suffix
    end.

ensure_schema_loaded() ->
    case pt_get_schema(undefined) of
        undefined ->
            Res = load_schema(),
            %% ?LOG_INFO("Schema Res = ~p", [Res]),
            Res;
        S ->
            S
    end.

load_schema() ->
    JSON = gmconfig_schema(),
    Decode = maps:get("json", config_formats()),
    Schema = decode_bin(JSON, Decode),
    pt_set_schema(Schema),
    Schema.

gmconfig_schema() ->
    case gmconfig_env(schema, #{}) of
        File when is_list(File) ->
            json_consult(File);
        Json when is_map(Json) ->
            Json;
        F when is_function(F, 0) ->
            F()
    end.

json_consult(F) ->
    Decode = maps:get("json", config_formats()),
    case setup_file:read_file(F) of
        {ok, Bin} ->
            decode_bin(Bin, Decode);
        {error, Reason} ->
            ?LOG_ERROR("Read error ~s - ~p", [F, Reason]),
            error({read_error, F, Reason})
    end.