doc/plugin.txt

   1 A FEW NOTES ON THE PLUGIN ARCHITECTURE
   2 ======================================
   3
   4 The plugin architecture of SquirrelMail is designed to make it
   5 possible to add new features without having to patch SquirrelMail
   6 itself. At the moment the plugin part of SquirrelMail should be
   7 considered "alpha" or "beta" quality code.
   8
   9 Until the functionality and code is more stable, be prepared for
  10 plugins to suddenly stop working.
  11
  12 Functionality like password changing, displaying ads and calendars
  13 should be possible to add as plugins.
  14
  15
  16 The idea
  17 --------
  18
  19 The idea is to be able to run random code at given places in the
  20 SquirrelMail code. This random code should then be able to do whatever
  21 needed to enhance the functionality of SquirrelMail. The places where
  22 code can be executed are called "hooks".
  23
  24 There are some limitations in what these hooks can do. It is difficult
  25 to use them to change the layout and to change functionality that
  26 already is in SquirrelMail.
  27
  28 Some way for the plugins to interact with the help subsystem and
  29 translations will be provided.
  30
  31
  32 The implementation
  33 ------------------
  34
  35 In the main SquirrelMail files the file functions/plugin.php. In
  36 places where hooks are made available they are executed by calling the
  37 function do_hook("hookname").
  38
  39 The do_hook traverses the array $squirrelmail_plugin_hooks["hookname"]
  40 and executes all the functions that are named in that array.
  41
  42 A plugin must reside in a subdirectory in the plugins/ directory. The
  43 name of the subdirectory is considered the name of the plugin.
  44
  45 To start using a plugin, its name must be added to the $plugins array
  46 in config.php like this:
  47
  48   $plugins[0] = "plugin_name";
  49
  50 When a plugin is registered the file plugins/plugin_name/setup.php is
  51 included and the function squirrelmail_plugin_init_plugin_name is
  52 called with no parameters.
  53
  54
  55 Writing plugins
  56 ---------------
  57
  58 A plugin must consist of at least a file called setup.php. All other
  59 files the plugin consist of should also be in the plugin directory.
  60
  61 The function squirrelmail_plugin_init_plugin_name is called to
  62 initalize a plugin. This function could look something like this:
  63
  64 function squirrelmail_plugin_init_demo () {
  65   global $squirrelmail_plugin_hooks;
  66
  67   $squirrelmail_plugin_hooks["generic_header"]["demo"] = "plugin_demo_header";
  68   $squirrelmail_plugin_hooks["menuline"]["demo"] = "plugin_demo_menuline";
  69 }
  70
  71 Note that the SquirrelMail files assume that all other SquirrelMail
  72 files are available as ../directory/file. This means that if some file
  73 in the plugin directory is requested, it must do a chdir("..") before
  74 including any of the standard SquirrelMail files.
  75
  76
  77 Hook Data Passed
  78 ----------------
  79 Hooks, when executed, are called with one parameter, an array of data
  80 that is passed to the hook.  The first element in the array is the name
  81 of the hook that is being called.  Any other elements in the array are
  82 dependant on the type of hook that is being called.
  83
  84 Some of the information in the array may be changed.  By default, the
  85 plugins should never change data unless it is documented otherwise.
  86
  87
  88 List of hooks
  89 -------------
  90   generic_header                  functions/page_header.php
  91   menuline                        functions/page_header.php
  92   compose_button_row              src/compose.php
  93   compose_bottom                  src/compose.php
  94   compose_form                    src/compose.php
  95   left_main_before                src/left_main.php
  96   left_main_after                 src/left_main.php
  97   * options_save                  src/options.php  (see note on options)
  98   * options_link_and_description  src/options.php  (see note on options)
  99   * options_highlight_bottom      src/options_highlight.php
 100   * options_personal_bottom       src/options_personal.php
 101   * options_personal_inside       src/options_personal.php
 102   * options_personal_save         src/options_personal.php
 103   * options_display_bottom        src/options_display.php
 104   * options_display_inside        src/options_display.php
 105   * options_display_save          src/options_display.php
 106   * options_folders_bottom        src/options_folders.php
 107   * options_folders_inside        src/options_folders.php
 108   * options_folders_save          src/options_folders.php
 109   logout                          src/signout.php
 110   login_before                    src/webmail.php
 111   login_verified                  src/webmail.php
 112   loading_prefs                   src/load_prefs.php
 113   mailbox_index_before            functions/mailbox_display.php
 114   mailbox_index_after             functions/mailbox_display.php
 115   mailbox_form_before             functions/mailbox_display.php
 116   subject_link                    functions/mailbox_display.php
 117   right_main_after_header         src/right_main.php
 118   right_main_bottom               src/right_main.php
 119   login_top                       src/login.php
 120   login_bottom                    src/login.php
 121   html_top                        src/read_body.php
 122   read_body_top                   src/read_body.php
 123   read_body_bottom                src/read_body.php
 124   html_bottom                     src/read_body.php
 125   read_body_header                src/read_body.php
 126   search_before_form              src/search.php
 127   search_after_form               src/search.php
 128   search_bottom                   src/search.php
 129   help_top                        src/help.php
 130   help_bottom                     src/help.php
 131   help_chapter                    src/help.php
 132   addrbook_html_search_below      src/addrbook_search_html.php
 133   addressbook_bottom              src/addressbook.php
 134   ^ attachment $type0/$type1      functions/mime.php (see note on attachments)
 135
 136
 137 (*) Options
 138 -----------
 139 There are two ways to do options for your plugin.  First, you can incorporate it
 140 into an existing section of the preferences (Display, Personal, or Folders).
 141 The second way, you create your own section that they can choose from and it
 142 displays its own range of options.
 143
 144
 145 First:  Integrating into existing options
 146 -----------------------------------------
 147 There are two hooks you need to use for this one:
 148
 149 1.  options_YOUCHOOSE_inside
 150     This is the code that goes inside the table for the section you choose.  Since
 151     it is going inside an existing table, it must be in this form:
 152     ------cut here-------
 153       <tr>
 154          <td>
 155             OPTION_NAME
 156          </td>
 157          <td>
 158             OPTION_INPUT
 159          </td>
 160       </tr>
 161     ------cut here-------
 162
 163 2.  options_YOUCHOOSE_save
 164     This is the code that saves your preferences into the users' preference
 165     file.  For an example of how to do this, see src/options.php.
 166
 167
 168 Second:  Create your own section
 169 -------------------------------
 170 It is possible to create your own options sections with plugins.  There are
 171 three hooks you will need to use.
 172
 173 1.  options_link_and_description
 174     This creates the link and has a description that are shown on the options
 175     page.  This should output HTML that looks like this:
 176
 177     -----cut here-----
 178       function my_function() {
 179          global $color
 180          ?>
 181          <table width=50% cellpadding=3 cellspacing=0 border=0 align=center>
 182             <tr>
 183                <td bgcolor="<? echo $color[9] ?>">
 184                   <a href="../plugins/YOUR_PLUGIN/YOUR_OPTIONS.php">YOUR OPTIONS NAME</a>
 185                </td>
 186             </tr>
 187             <tr>
 188                <td bgcolor="<? echo $color[0] ?>">
 189                   YOUR DESCRIPTION
 190                </td>
 191             </tr>
 192          </table>
 193          <?php
 194       }
 195     -----cut here-----
 196
 197 2.  options_save
 198     Here is the code that you need to do to save your options in the
 199     preference files or manipulate whatever data you are trying to change
 200     through the options section.  You can look at options.php for details
 201     on how this is to be done.
 202
 203 3.  loading_prefs (optional)
 204     If you are wanting to save preferences to the preference files, then
 205     you need to do this step as well.  Otherwise if you are manipulating
 206     other data, ignore this step.
 207
 208     You should put the code in here that loads your preferences back
 209     into usable variables.  Examples of this can be found in the file
 210     src/load_prefs.php
 211
 212
 213 (^) Attachment Hooks
 214 --------------------
 215 When a message has attachments, this hook is called with the MIME types.  For
 216 instance, a .zip file hook is "attachment application/x-zip".  The hook should
 217 probably show a link to do a specific action, such as "Verify" or "View" for a
 218 .zip file.
 219
 220 This is a breakdown of the data passed in the array to the hook that is called:
 221
 222   [0] = Hook's name ('attachment text/plain')
 223   [1] = Array of links of actions (more below) (Alterable)
 224   [2] = Used for returning to mail message (startMessage)
 225   [3] = Used for finding message to display (id)
 226   [4] = Mailbox name, urlencode()'d (urlMailbox)
 227   [5] = Entity ID inside mail message (ent)
 228   [6] = Default URL to go to when filename is clicked on (Alterable)
 229   [7] = Filename that is displayed for the attachment
 230   [8] = Sent if message was found from a search (where)
 231   [9] = Sent if message was found from a search (what)
 232
 233 To set up links for actions, you assign them like this:
 234
 235   $Args[1]['your_plugin_name']['href'] = 'URL to link to';
 236   $Args[1]['your_plugin_name']['text'] = 'What to display';
 237