%% @author Maas-Maarten Zeeman <mmzeeman@xs4all.nl>
%% @copyright 2019-2026 Maas-Maarten Zeeman
%% @doc Zotonic: admin status model
%% @end

%% Copyright 2019-2026 Maas-Maarten Zeeman
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.

-module(m_admin_status).
-moduledoc("
Model for admin status endpoints, including Zotonic version and health/status overview values.

Available Model API Paths
-------------------------

| Method | Path pattern | Description |
| --- | --- | --- |
| `get` | `/zotonic_version/...` | Return the running Zotonic version string for admin users (ACL-protected). |
| `get` | `/zotonic_git_version/...` | Return the running Zotonic's git version string for admin users (ACL-protected). |
| `get` | `/database_version/...` | Return the database server version string (admin ACL-gated via `m_get/3`). |
| `get` | `/otp_version/...` | Return the exact Erlang/OTP version string (admin ACL-gated via `m_get/3`). |
| `get` | `/config_dir/...` | Return the active configuration directory path. |
| `get` | `/security_dir/...` | Return the configured security directory path (`z_config:get(security_dir)`). |
| `get` | `/log_dir/...` | Return the configured log directory path (`z_config:get(log_dir)`). |
| `get` | `/data_dir/...` | Return the configured data directory path (`z_config:get(data_dir)`). |
| `get` | `/cache_dir/...` | Return the configured cache directory path (`z_config:get(cache_dir)`). |
| `get` | `/work_dir/...` | Return the current working directory of the running node. |
| `get` | `/files_dir/...` | Return the site files base directory derived from `z_path:files_subdir/2`. |
| `get` | `/tcp_connection_count/...` | Return the current number of open TCP sockets (`recon:tcp/0`). |
| `get` | `/group_sockets/...` | Return open TCP sockets grouped by peer IP with counts and ports. |
| `get` | `/memory/used/...` | Return memory usage grouped by allocator (`recon_alloc:memory(used)`). |
| `get` | `/memory/allocated/...` | Return allocated memory grouped by allocator (`recon_alloc:memory(allocated)`). |
| `get` | `/memory/unused/...` | Return unused memory grouped by allocator (`recon_alloc:memory(unused)`). |
| `get` | `/memory/usage/...` | Return allocator memory usage ratios (`recon_alloc:memory(usage)`). |
| `get` | `/disks/...` | Return disk space information for mounted disks. |
| `get` | `/disks/alert/...` | Return whether any disk usage crosses configured alert thresholds. |
| `get` | `/os_memory/...` | Return operating-system memory statistics. |
| `get` | `/os_memory/alert/...` | Return whether OS memory pressure crosses alert thresholds. |
| `get` | `/task_queue/...` | Return pivot/task queue counters from `z_pivot_rsc:count_tasks/1`. |
| `get` | `/is_ssl_application_configured/...` | Return whether the `ssl` application has session settings configured. |
| `get` | `/init_arguments/...` | Return all Erlang VM init arguments (`init:get_arguments/0`). |
| `get` | `/init_arguments/config/...` | Return only `-config` init argument values. |

`/+name` marks a variable path segment. A trailing `/...` means extra path segments are accepted for further lookups.
").
-author("Maas-Maarten Zeeman <mmzeeman@xs4all.nl>").

-behaviour(zotonic_model).

-include_lib("zotonic_core/include/zotonic_release.hrl").
-include_lib("zotonic_core/include/zotonic.hrl").


%% interface functions
-export([
    m_get/3,

    otp_version/0,
    zotonic_version/0,
    zotonic_git_version/0,
    database_version/1,
    tcp_connection_count/0,
    group_sockets/0,
    close_sockets/2,
    disks/0,
    disks_alert/0
]).

-spec m_get( list(), zotonic_model:opt_msg(), z:context()) -> zotonic_model:return().
m_get([ <<"zotonic_version">> | Rest ], _Msg, Context) ->
    case z_acl:is_admin(Context) of
        true -> {ok, {zotonic_version(), Rest}};
        false -> {error, eacces}
    end;
m_get([ <<"zotonic_git_version">> | Rest ], _Msg, Context) ->
    case z_acl:is_admin(Context) of
        true -> {ok, {zotonic_git_version(), Rest}};
        false -> {error, eacces}
    end;
m_get(Path, Msg, Context) ->
    case z_acl:is_admin(Context) of
        true -> m_get_1(Path, Msg, Context);
        false -> {error, eacces}
    end.


m_get_1([ <<"database_version">> | Rest ], _Msg, Context) ->
    case z_acl:is_admin(Context) of
        true -> {ok, {database_version(Context), Rest}};
        false -> {error, eacces}
    end;
m_get_1([ <<"otp_version">> | Rest ], _Msg, Context) ->
    case z_acl:is_admin(Context) of
        true -> {ok, {otp_version(), Rest}};
        false -> {error, eacces}
    end;
m_get_1([ <<"config_dir">> | Rest ], _Msg, _Context) ->
    case z_config_files:config_dir() of
        {ok, Dir} ->
            {ok, {Dir, Rest}};
        {error, _} = Error ->
            Error
    end;
m_get_1([ <<"security_dir">> | Rest ], _Msg, _Context) ->
    {ok, {z_config:get(security_dir), Rest}};
m_get_1([ <<"log_dir">> | Rest ], _Msg, _Context) ->
    {ok, {z_config:get(log_dir), Rest}};
m_get_1([ <<"data_dir">> | Rest ], _Msg, _Context) ->
    {ok, {z_config:get(data_dir), Rest}};
m_get_1([ <<"cache_dir">> | Rest ], _Msg, _Context) ->
    {ok, {z_config:get(cache_dir), Rest}};
m_get_1([ <<"work_dir">> | Rest ], _Msg, _Context) ->
    case file:get_cwd() of
        {ok, Dir} ->
            {ok, {unicode:characters_to_binary(Dir), Rest}};
        {error, _} = Error ->
            Error
    end;
m_get_1([ <<"files_dir">> | Rest ], _Msg, Context) ->
    Dir = z_path:files_subdir(".", Context),
    {ok, {filename:dirname(unicode:characters_to_binary(Dir)), Rest}};
m_get_1([ <<"tcp_connection_count">> | Rest ], _Msg, _Context) ->
    {ok, {tcp_connection_count(), Rest}};

m_get_1([ <<"group_sockets">> | Rest ], _Msg, _Context) ->
    {ok, {group_sockets(), Rest}};

m_get_1([ <<"memory">>, <<"used">> | Rest ], _Msg, _Context) ->
    {ok, {recon_alloc:memory(used), Rest}};
m_get_1([ <<"memory">>, <<"allocated">> | Rest ], _Msg, _Context) ->
    {ok, {recon_alloc:memory(allocated), Rest}};
m_get_1([ <<"memory">>, <<"unused">> | Rest ], _Msg, _Context) ->
    {ok, {recon_alloc:memory(unused), Rest}};
m_get_1([ <<"memory">>, <<"usage">> | Rest ], _Msg, _Context) ->
    {ok, {recon_alloc:memory(usage), Rest}};

m_get_1([ <<"disks">>, <<"alert">> | Rest ], _Msg, _Context) ->
    {ok, {disks_alert(), Rest}};
m_get_1([ <<"disks">> | Rest ], _Msg, _Context) ->
    {ok, {disks(), Rest}};

m_get_1([ <<"os_memory">>, <<"alert">> | Rest ], _Msg, _Context) ->
    {ok, {os_memory_alert(), Rest}};
m_get_1([ <<"os_memory">> | Rest ], _Msg, _Context) ->
    {ok, {os_memory(), Rest}};

m_get_1([ <<"task_queue">> | Rest ], _Msg, Context) ->
    case z_pivot_rsc:count_tasks(Context) of
        {ok, Ts} ->
            {ok, {Ts, Rest}};
        {error, _} = Error ->
            Error
    end;

m_get_1([ <<"is_ssl_application_configured">> | Rest ], _Msg, _Context) ->
    IsConf = case application:get_env(ssl, session_lifetime) of
        undefined -> false;
        {ok, _} -> true
    end,
    {ok, {IsConf, Rest}};

m_get_1([ <<"init_arguments">>, <<"config">> | Rest ], _Msg, _Context) ->
    {ok, {proplists:get_all_values(config, init:get_arguments()), Rest}};

m_get_1([ <<"init_arguments">> | Rest ], _Msg, _Context) ->
    {ok, {init:get_arguments(), Rest}};

m_get_1(_Path, _Msg, _Context) ->
    {error, unknown_path}.


%%
%% Helpers
%%

% Return the total number of open tcp connections in the system.
% This includes local sockets.
tcp_connection_count() ->
    length(recon:tcp()).

%% @doc Return the exact OTP version.
-spec otp_version() -> binary().
otp_version() ->
    OtpVersionFile = filename:join([
        code:root_dir(),
        "releases",
        erlang:system_info(otp_release),
        "OTP_VERSION"
    ]),
    {ok, Version} = file:read_file(OtpVersionFile),
    z_string:trim(Version).


%% @doc Return the zotonic version.
-spec zotonic_version() -> binary().
zotonic_version() ->
    z_convert:to_binary(?ZOTONIC_VERSION).

%% @doc Return the zotonic's git version.
-spec zotonic_git_version() -> binary() | undefined.
zotonic_git_version() ->
    case z_memo:get(zotonic_git_version) of
        {cached, Version} ->
            Version;
        _ ->
            % NOTE: this cached value is flushed by 'mod_admin:observe_filewatcher/2'
            GitVersion = z_utils:git_version(z_path:get_path()),
            z_memo:set(zotonic_git_version, {cached, GitVersion}),
            GitVersion
    end.

%% @doc Return the version string of the used database.
-spec database_version( z:context() ) -> binary().
database_version(Context) ->
    z_db:database_version_string(Context).

% Group open sockets per ip-address, returns a list of proplists.
group_sockets() ->
    Dict = group_sockets(recon:tcp(), dict:new()),
    [[{count, length(Ports)}, {ip, inet:ntoa(IP)}, {ports, Ports}] || {IP, Ports} <- dict:to_list(Dict)].

% Return a dict with as key the ip-address. 
group_sockets([], Dict) ->
    Dict;
group_sockets([Port|Rest], Dict) ->
    case inet:peername(Port) of
        {ok, {Addr, _}} ->
            group_sockets(Rest, dict:append_list(Addr, [Port], Dict));
        _ ->
            group_sockets(Rest, Dict)
    end.

% Close sockets
close_sockets(Max, _Context) ->
    socket_reaper(Max).

% Close sockets of ip-addresses which have 
socket_reaper(Max) ->
    Dict = group_sockets(recon:tcp(), dict:new()),
    socket_reaper(dict:to_list(Dict), Max, 0).

socket_reaper([], _Max, Acc) ->
    Acc;
socket_reaper([{_Ip, Ports}|Rest], Max, Acc) when length(Ports) >= Max ->
    [inet:close(Port) || Port <- Ports],
    socket_reaper(Rest, Max, length(Ports) + Acc);
socket_reaper([_|Rest], Max, Acc) ->
    socket_reaper(Rest, Max, Acc).


%% @doc Return disk space information
-spec disks() -> list( map() ).
disks() ->
    DiskData = disksup:get_disk_data(),
    Threshold = disks_threshold(),
    lists:filtermap(
        fun({Disk, Size, Capacity}) ->
            DiskBin = unicode:characters_to_binary(Disk),
            case is_hidden_disk(DiskBin) of
                true ->
                    false;
                false ->
                    {true, #{
                        disk => DiskBin,
                        size => Size,
                        percent_used => Capacity,
                        alert => Capacity > Threshold
                    }}
            end
        end,
        DiskData).

%% @doc Hide macOS system disks from the overview and disk space checks.
is_hidden_disk(<<"/Library/Developer/CoreSimulator/", _/binary>>) -> true;
is_hidden_disk(<<"/System/Volumes/xarts">>) -> true;
is_hidden_disk(<<"/System/Volumes/iSCPreboot">>) -> true;
is_hidden_disk(<<"/System/Volumes/Hardware">>) -> true;
is_hidden_disk(<<"/System/Volumes/Preboot">>) -> true;
is_hidden_disk(<<"/System/Volumes/VM">>) -> true;
is_hidden_disk(_) -> false.

%% @doc Return disk space information
-spec disks_alert() -> boolean().
disks_alert() ->
    DiskData = disksup:get_disk_data(),
    Threshold = disks_threshold(),
    lists:any(
        fun({Disk, _Size, Capacity}) ->
            DiskBin = unicode:characters_to_binary(Disk),
            not is_hidden_disk(DiskBin) andalso (Capacity > Threshold)
        end,
        DiskData).

%% @doc Return the percentage to be used as threshold.
disks_threshold() ->
    disksup:get_almost_full_threshold().


%% @doc Return true iff the system_memory alert is set.
-spec os_memory_alert() -> boolean().
os_memory_alert() ->
    false.
    % FIXME
    % This can be enabled again after the following fix has been merged to OTP:
    % https://github.com/erlang/otp/pull/8776
    %
    % Alarms = alarm_handler:get_alarms(),
    % lists:any(
    %   fun
    %       ({system_memory_high_watermark, _}) -> true;
    %       (_) -> false
    %   end,
    %   Alarms).

%% @doc Return a list with os memory statistics.
os_memory() ->
    memsup:get_system_memory_data().