%%%-------------------------------------------------------------------
%%% @doc `/browser' API domain -- a direct, session/tab-scoped path
%%% to the same typed operations `hk_agent_toolbox' calls for an
%%% agent. This is for operator/manual use (opening a session from
%%% the frontend's "browser" view without an agent involved) and for
%%% tests; it goes through the *same* `hk_browser_session' module
%%% and therefore the *same* structured events as agent-driven
%%% browser use -- there is exactly one code path that talks to
%%% Chromium, regardless of who asked.
%%%
%%%   POST /api/browser/sessions                                create
%%%   GET  /api/browser/sessions                                list
%%%   GET  /api/browser/sessions/:id                             describe
%%%   POST /api/browser/sessions/:id/close                       close
%%%   POST /api/browser/sessions/:id/tabs                        open a tab
%%%   POST /api/browser/sessions/:id/tabs/:tab_id/navigate       navigate
%%%   POST /api/browser/sessions/:id/tabs/:tab_id/actions        {op, args}:
%%%        op in back|forward|reload|read_page|query_element|click|type|
%%%           scroll|screenshot|extract_links|close
%%% @end
%%%-------------------------------------------------------------------
-module(hk_api_browser_h).

-export([init/2]).

init(Req0 = #{method := <<"POST">>}, collection) ->
    RequestId = hk_api_util:request_id(Req0),
    {ok, Body, Req1} = hk_api_util:read_json_body(Req0),
    OwnerAgentId = maps:get(<<"owner_agent_id">>, Body, undefined),
    Profile = maps:get(<<"profile">>, Body, <<"manual">>),
    Req = hk_api_util:run_operation(browser_create_session, RequestId, fun() ->
        SessionId = hk_id:new(<<"sess">>),
        case hk_browser_session_sup:start_session(#{session_id => SessionId,
                                                      owner_agent_id => OwnerAgentId, profile => Profile}) of
            {ok, _Pid} -> {ok, {browser_session, SessionId}, #{session_id => SessionId}};
            {error, Reason} -> {error, Reason}
        end
    end, Req1),
    {ok, Req, collection};

init(Req0 = #{method := <<"GET">>}, collection) ->
    Sessions = [describe_or_skip(Id) || {Id, _Pid} <- hk_browser_registry:list_sessions()],
    Req = hk_api_util:reply_json(200, #{sessions => [M || {true, M} <- Sessions]}, Req0),
    {ok, Req, collection};

init(Req0 = #{method := <<"GET">>}, item) ->
    SessionId = cowboy_req:binding(id, Req0),
    Req = case hk_browser_registry:lookup(SessionId) of
              {ok, Pid} ->
                  {ok, Session} = hk_browser_session:describe(Pid),
                  hk_api_util:reply_json(200, hk_schema:to_map(Session), Req0);
              {error, not_found} ->
                  hk_api_util:reply_error(404, session_not_found, Req0)
          end,
    {ok, Req, item};

init(Req0 = #{method := <<"POST">>}, close) ->
    SessionId = cowboy_req:binding(id, Req0),
    RequestId = hk_api_util:request_id(Req0),
    Req = hk_api_util:run_operation(browser_close_session, RequestId, fun() ->
        with_session(SessionId, fun(Pid) ->
            hk_browser_session:close_session(Pid),
            {ok, {browser_session, SessionId}, #{}}
        end)
    end, Req0),
    {ok, Req, close};

init(Req0 = #{method := <<"POST">>}, tabs) ->
    SessionId = cowboy_req:binding(id, Req0),
    RequestId = hk_api_util:request_id(Req0),
    {ok, Body, Req1} = hk_api_util:read_json_body(Req0),
    Url = maps:get(<<"url">>, Body, <<"about:blank">>),
    Req = hk_api_util:run_operation(browser_open_tab, RequestId, fun() ->
        with_session(SessionId, fun(Pid) ->
            case hk_browser_session:open_tab(Pid, Url) of
                {ok, TabId} -> {ok, {browser_tab, TabId}, #{tab_id => TabId}};
                {error, Reason} -> {error, Reason}
            end
        end)
    end, Req1),
    {ok, Req, tabs};

init(Req0 = #{method := <<"POST">>}, navigate) ->
    SessionId = cowboy_req:binding(id, Req0),
    TabId = cowboy_req:binding(tab_id, Req0),
    RequestId = hk_api_util:request_id(Req0),
    {ok, Body, Req1} = hk_api_util:read_json_body(Req0),
    Url = maps:get(<<"url">>, Body, <<>>),
    Req = hk_api_util:run_operation(browser_navigate, RequestId, fun() ->
        with_session(SessionId, fun(Pid) ->
            case hk_browser_session:navigate(Pid, TabId, Url) of
                ok -> {ok, {browser_tab, TabId}, #{}};
                {error, Reason} -> {error, Reason}
            end
        end)
    end, Req1),
    {ok, Req, navigate};

init(Req0 = #{method := <<"POST">>}, actions) ->
    SessionId = cowboy_req:binding(id, Req0),
    TabId = cowboy_req:binding(tab_id, Req0),
    RequestId = hk_api_util:request_id(Req0),
    {ok, Body, Req1} = hk_api_util:read_json_body(Req0),
    Op = binary_to_atom(maps:get(<<"op">>, Body, <<"read_page">>), utf8),
    Args = maps:get(<<"args">>, Body, #{}),
    Req = hk_api_util:run_operation(browser_tab_action, RequestId, fun() ->
        with_session(SessionId, fun(Pid) -> dispatch(Pid, Op, TabId, Args) end)
    end, Req1),
    {ok, Req, actions};

init(Req0, State) ->
    Req = hk_api_util:reply_error(405, method_not_allowed, Req0),
    {ok, Req, State}.

%%% internal

with_session(undefined, _Fun) -> {error, missing_session_id};
with_session(SessionId, Fun) ->
    case hk_browser_registry:lookup(SessionId) of
        {ok, Pid} -> Fun(Pid);
        {error, not_found} -> {error, session_not_found}
    end.

dispatch(Pid, back, TabId, _Args) -> as_op(hk_browser_session:back(Pid, TabId), TabId);
dispatch(Pid, forward, TabId, _Args) -> as_op(hk_browser_session:forward(Pid, TabId), TabId);
dispatch(Pid, reload, TabId, _Args) -> as_op(hk_browser_session:reload(Pid, TabId), TabId);
dispatch(Pid, close, TabId, _Args) -> as_op(hk_browser_session:close_tab(Pid, TabId), TabId);
dispatch(Pid, read_page, TabId, _Args) ->
    as_result(hk_browser_session:read_page(Pid, TabId), TabId, text);
dispatch(Pid, query_element, TabId, Args) ->
    Selector = maps:get(<<"selector">>, Args, <<>>),
    as_result(hk_browser_session:query_element(Pid, TabId, Selector), TabId, element);
dispatch(Pid, click, TabId, Args) ->
    Selector = maps:get(<<"selector">>, Args, <<>>),
    as_result(hk_browser_session:click(Pid, TabId, Selector), TabId, click);
dispatch(Pid, type, TabId, Args) ->
    Selector = maps:get(<<"selector">>, Args, <<>>),
    Text = maps:get(<<"text">>, Args, <<>>),
    as_result(hk_browser_session:type(Pid, TabId, Selector, Text), TabId, type);
dispatch(Pid, scroll, TabId, Args) ->
    Dy = maps:get(<<"delta_y">>, Args, 0),
    as_result(hk_browser_session:scroll(Pid, TabId, Dy), TabId, scroll);
dispatch(Pid, screenshot, TabId, _Args) ->
    as_result(hk_browser_session:screenshot(Pid, TabId), TabId, screenshot_base64);
dispatch(Pid, extract_links, TabId, _Args) ->
    as_result(hk_browser_session:extract_links(Pid, TabId), TabId, links);
dispatch(_Pid, Op, _TabId, _Args) ->
    {error, {unsupported_op, Op}}.

as_op(ok, TabId) -> {ok, {browser_tab, TabId}, #{}};
as_op({error, Reason}, _TabId) -> {error, Reason}.

as_result({ok, Value}, TabId, Key) -> {ok, {browser_tab, TabId}, #{Key => Value}};
as_result({error, Reason}, _TabId, _Key) -> {error, Reason}.

describe_or_skip(SessionId) ->
    case hk_browser_registry:lookup(SessionId) of
        {ok, Pid} ->
            case catch hk_browser_session:describe(Pid) of
                {ok, Session} -> {true, hk_schema:to_map(Session)};
                _ -> false
            end;
        _ -> false
    end.