*Project*                            The Anubis Project
 *Title*                         Some common stuff for the web. 

 *Copyright*                    
  Copyright (c) Alain Prouté 2003~2007.
  © Calexium 2007~2016
 
 
 *Authors:* 
  Alain Prouté
  David René
  
 *Public*
 *Name* HTTP_header
 *Description*  
 
transmit tools/basis.anubis
transmit system/string.anubis
 
/**
 * The type 'HTTP_header' describes HTTP headers, which are just pairs '(name,value)'.
 */
public type HTTP_header:
   http_header(String name, 
               String value). 


public define Maybe(String)
  http_header_value
    (
      List(HTTP_header) l,
      String name
    ) =
  if l is
    {
      [ ] then failure,
      [h . t] then if h is 
        {
          http_header(n, v) then //print("DEBUG: http_header_value --> HEADER = " + n + ":" + v + "\n");
            if insensitive_equal(name, n) then   success(v)
                                          else   http_header_value(t, name),
        }
    }. 

public define List(String)
  to_List_String
  (
    List(HTTP_header) l
  )=
  map((HTTP_header h) |-> h.name +": "+h.value, l ).
  
public define String
  to_String
  (
    List(HTTP_header) l
  )=
  join("\n\r",to_List_String(l)).
  
  
 *Name* Web_arg
 *Description*

   The  type  'Web_arg' describes  'web  arguments'.   A web  argument  is  either a  pair
   '(name,value)'  (for example it  may be  'web_arg("password","foobar")', if  the client
   clicks  on  the submit  button  of  a form  containing  a  password  input field  named
   'password'), or  an uploaded file. In  this last case,  it is a triplet  containing the
   name  of the  file upload  input field,  the value  of this  input field  (name  of the
   uploaded  file), and the  name of  the temporary  file as  saved by  the server  in its
   'upload temporary directory'; see 'web/http_server.anubis' and the 'upload' Web_item in
   'web/html.anubis').
   
public type Web_arg: 
  web_arg(String name, 
          String value),
  upload (String name,               // name of corresponding 'upload' Web_item
          String value,              // name of uploaded file 
          String temp_file_path).    // temporary file path (relative to server directory)   

   
 *Name* Web_arg_value
 *Description*
   Of course, within the body of a 'web page' operation, you may want to recover the value
   of a  particular web argument.  To that end,  use the operation  'web_arg_value', which
   takes 2 argument:
   
    - the list of all web arguments (the operand of the web page operation), 
    - the name of the argument whose value is wanted. 

   This operation has the following return type:

public type Web_arg_value:
  not_found, 
  found(String value). 

 *Name* Web_arg_value
 *Description*
   If  the   requested  argument  name   is  not  found   in  the  list,   'not_found'  is
   returned. Otherwise,  the value  returned by 'web_arg_value'  has the  form 'found(v)',
   where 'v' is the value of the argument.

   The operation 'web_arg_value' is defined below. 

public define Web_arg_value
  web_arg_value
    (
      List(Web_arg) l,
      String name
    ) =
  if l is
    {
      [ ] then not_found,
      [h . t] then if h is 
        {
          web_arg(n,v) then 
            if     name=n 
            then   found(v)
            else   web_arg_value(t,name),
   
          upload(n,v,tfn) then 
            if     name=n 
            then   found(v)
            else   web_arg_value(t,name)
        }
    }. 

public define Web_arg_value
  web_arg_value_not_null
  (
    List(Web_arg) lwa,
    String        name,
    ) =
  if web_arg_value(lwa, name) is
  {
    not_found   then not_found
    found(str)  then
      if str = "" then
        not_found
      else
        found(str)
  }.
  
 *Ignore*

public define Maybe((String,String))
   file_upload_value
     (
       List(Web_arg)     l,
       String            name
     ) =
   if l is 
     {
       [ ] then failure, 
       [h . t] then if h is 
         {
           web_arg(_,_) then file_upload_value(t,name), 
           upload(n,v,tfn) then 
             if n = name
             then success((v,tfn))
             else file_upload_value(t,name)
         }
     }.

public define List((String,String))
   file_upload_value
     (
       List(Web_arg)          l,
       String                 name,
       List((String,String))  new_list
     ) =
   if l is 
     {
       [ ] then new_list, 
       [h . t] then if h is 
         {
           web_arg(_,_) then file_upload_value(t,name, new_list), 
           upload(n,v,tfn) then 
             if n = name
             then file_upload_value(t,name, [(v,tfn) . new_list])
             else file_upload_value(t,name, new_list)
         }
     }.     

   
public type Redirection:
   redirect(String required_uri,        // URI required by the client
            String required_host,       // value of 'Host' HTTP header sent by the client
            String corresponding_uri).  // URI which will be served to the client

public type Redirections:
  redirection_list(List(Redirection) redirections),
  redirection_fn((String input_uri,      // URI required by the client
                  String host)   -> String f).        // value of 'Host' HTTP header sent by the client
   
   
   Now, you  may also  want to  recover web argument  values which  have been  encoded (by
   'web_arg_encode'). In this case, use the following:
   
read CXM_web_arg_encode.anubis   
   
   
public define Maybe($T)   
   decode_web_arg_value
     (
       List(Web_arg)    l, 
       String           name 
     ) =
   if web_arg_value(l,name) is 
     {
       not_found     then failure, 
       found(v)      then web_arg_decode(v)
     }.
   
public define List(String)
  web_arg_list_values
  (
    List(Web_arg) l,
    String        name
  ) =
  if l is
  {
    []      then [],
    [h . t] then
    if h is web_arg(n, v) then
    if n = name then
     [ v . web_arg_list_values(t, name)]
    else
      web_arg_list_values(t, name)
    else
      web_arg_list_values(t, name)
      
  }
  .