unit WeatherAPI;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs,  ShellApi,  ActiveX,  ComObj,  WinInet, StdCtrls;


type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

const
   Weather = 'api.openweathermap.org/data/2.5/weather?q=London,uk&units=metric&APPID=3b2ad077bd300f6880a9657fff39a432';

procedure WinInet_HttpGet(const Url: string;Stream:TStream);overload;
function   WinInet_HttpGet(const Url: string): string;overload;

implementation

{$R *.dfm}

procedure WinInet_HttpGet(const Url: string;Stream:TStream);overload;
const
BuffSize = 1024*1024;
var
  hInter   : HINTERNET;
  UrlHandle: HINTERNET;
  BytesRead: DWORD;
  Buffer   : Pointer;
begin
  hInter := InternetOpen('', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
  if Assigned(hInter) then
    try
      Stream.Seek(0,0);
      GetMem(Buffer,BuffSize);
      try
          UrlHandle := InternetOpenUrl(hInter, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD, 0);
          if Assigned(UrlHandle) then
          begin
            repeat
              InternetReadFile(UrlHandle, Buffer, BuffSize, BytesRead);
              if BytesRead>0 then
               Stream.WriteBuffer(Buffer^,BytesRead);
            until BytesRead = 0;
            InternetCloseHandle(UrlHandle);
          end;
      finally
        FreeMem(Buffer);
      end;
    finally
     InternetCloseHandle(hInter);
    end;
end;

function WinInet_HttpGet(const Url: string): string;overload;
Var
  StringStream : TStringStream;
begin
  Result:='';
    StringStream:=TStringStream.Create('');
    try
        WinInet_HttpGet(Url,StringStream);
        if StringStream.Size>0 then
        begin
          StringStream.Seek(0,0);
          Result:=StringStream.ReadString(StringStream.Size);
        end;
    finally
      StringStream.Free;
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 try
    CoInitialize(nil);
    try
    showmessage(WinInet_HttpGet(Weather));
    finally
      CoUninitialize;
    end;
 except
    on E:Exception do
        Showmessage(E.Classname+#13+E.Message);
 end;
end;

end.