/*
** Copyright (c) 2020 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the Simplified BSD License (also
** known as the "2-Clause License" or "FreeBSD License".)
**
** This program is distributed in the hope that it will be useful,
** but without any warranty; without even the implied warranty of
** merchantability or fitness for a particular purpose.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file contains code used to implement the Fossil chatroom.
**
** Initial design goals:
**
**    *   Keep it simple.  This chatroom is not intended as a competitor
**        or replacement for IRC, Discord, Telegram, Slack, etc.  The goal
**        is zero- or near-zero-configuration, not an abundance of features.
**
**    *   Intended as a place for insiders to have ephemeral conversations
**        about a project.  This is not a public gather place.  Think
**        "boardroom", not "corner pub".
**
**    *   One chatroom per repository.
**
**    *   Chat content lives in a single repository.  It is never synced.
**        Content expires and is deleted after a set interval (a week or so).
**
** Notification is accomplished using the "hanging GET" or "long poll" design
** in which a GET request is issued but the server does not send a reply until
** new content arrives.  Newer Web Sockets and Server Sent Event protocols are
** more elegant, but are not compatible with CGI, and would thus complicate
** configuration.
*/
#include "config.h"
#include <assert.h>
#include "chat.h"

/*
** Outputs JS code to initialize a list of chat alert audio files for
** use by the chat front-end client. A handful of builtin files
** (from alerts/\*.wav) and all unversioned files matching
** alert-sounds/\*.{mp3,ogg,wav} are included.
*/
static void chat_emit_alert_list(void){
  unsigned int i;
  const char * azBuiltins[] = {
  "builtin/alerts/plunk.wav",
  "builtin/alerts/bflat2.wav",
  "builtin/alerts/bflat3.wav",
  "builtin/alerts/bloop.wav"
  };
  CX("window.fossil.config.chat.alerts = [\n");
  for(i=0; i < sizeof(azBuiltins)/sizeof(azBuiltins[0]); ++i){
    CX("%s%!j", i ? ", " : "", azBuiltins[i]);
  }
  if( db_table_exists("repository","unversioned") ){
    Stmt q = empty_Stmt;
    db_prepare(&q, "SELECT 'uv/'||name FROM unversioned "
               "WHERE content IS NOT NULL "
               "AND (name LIKE 'alert-sounds/%%.wav' "
               "OR name LIKE 'alert-sounds/%%.mp3' "
               "OR name LIKE 'alert-sounds/%%.ogg')");
    while(SQLITE_ROW==db_step(&q)){
      CX(", %!j", db_column_text(&q, 0));
    }
    db_finalize(&q);
  }
  CX("\n];\n");
}

/* Settings that can be used to control chat */
/*
** SETTING: chat-initial-history    width=10 default=50
**
** If this setting has an integer value of N, then when /chat first
** starts up it initializes the screen with the N most recent chat
** messages.  If N is zero, then all chat messages are loaded.
*/
/*
** SETTING: chat-keep-count    width=10 default=50
**
** When /chat is cleaning up older messages, it will always keep
** the most recent chat-keep-count messages, even if some of those
** messages are older than the discard threshold.  If this value
** is zero, then /chat is free to delete all historic messages once
** they are old enough.
*/
/*
** SETTING: chat-keep-days    width=10 default=7
**
** The /chat subsystem will try to discard messages that are older then
** chat-keep-days.  The value of chat-keep-days can be a floating point
** number.  So, for example, if you only want to keep chat messages for
** 12 hours, set this value to 0.5.
**
** A value of 0.0 or less means that messages are retained forever.
*/
/*
** SETTING: chat-inline-images    boolean default=on
**
** Specifies whether posted images in /chat should default to being
** displayed inline or as downloadable links. Each chat user can
** change this value for their current chat session in the UI.
*/
/*
** SETTING: chat-poll-timeout    width=10 default=420
**
** On an HTTP request to /chat-poll, if there is no new content available,
** the reply is delayed waiting for new content to arrive.  (This is the
** "long poll" strategy of event delivery to the client.)  This setting
** determines approximately how long /chat-poll will delay before giving
** up and returning an empty reply.  The default value is about 7 minutes,
** which works well for Fossil behind the althttpd web server.  Other
** server environments may choose a longer or shorter delay.
**
** For maximum efficiency, it is best to choose the longest delay that
** does not cause timeouts in intermediate proxies or web server.
*/
/*
** SETTING: chat-alert-sound     width=10
**
** This is the name of the builtin sound file to use for the alert tone.
** The value must be the name of a builtin WAV file.
*/
/*
** SETTING: chat-timeline-user    width=10
**
** If this setting is defined and is not an empty string, then
** timeline events are posted to the chat as they arrive. The synthesized
** chat messages appear to come from the user identified by this setting,
** not the user on the timeline event.
**
** All chat messages that come from the chat-timeline-user are
** interpreted as text/x-fossil-wiki instead of as text/x-markdown.
** For this reason, the chat-timeline-user name should probably not be
** a real user.
*/
/*
** WEBPAGE: chat loadavg-exempt
**
** Start up a browser-based chat session.
**
** This is the main page that humans use to access the chatroom.  Simply
** point a web-browser at /chat and the screen fills with the latest
** chat messages, and waits for new ones.
**
** Other /chat-OP pages are used by XHR requests from this page to
** send new chat message, delete older messages, or poll for changes.
*/
void chat_webpage(void){
  char *zAlert;
  char *zProjectName;
  char * zInputPlaceholder0;  /* Common text input placeholder value */

  login_check_credentials();
  if( !g.perm.Chat ){
    login_needed(g.anon.Chat);
    return;
  }
  zAlert = mprintf("%s/builtin/%s", g.zBaseURL,
                db_get("chat-alert-sound","alerts/plunk.wav"));
  zProjectName = db_get("project-name","Unnamed project");
  zInputPlaceholder0 =
    mprintf("Type markdown-formatted message for %h.", zProjectName);
  style_set_current_feature("chat");
  style_header("Chat");
  @ <div id='chat-input-area'>
  @   <div id='chat-input-line-wrapper' class='compact'>
  @     <input type="text" id="chat-input-field-single" \
  @      data-placeholder0="%h(zInputPlaceholder0)" \
  @      data-placeholder="%h(zInputPlaceholder0)" \
  @      class="chat-input-field"></input>
  @     <textarea id="chat-input-field-multi" \
  @      data-placeholder0="%h(zInputPlaceholder0)" \
  @      data-placeholder="%h(zInputPlaceholder0)" \
  @      class="chat-input-field hidden"></textarea>
  @     <div contenteditable id="chat-input-field-x" \
  @      data-placeholder0="%h(zInputPlaceholder0)" \
  @      data-placeholder="%h(zInputPlaceholder0)" \
  @      class="chat-input-field hidden"></div>
  @     <div id='chat-buttons-wrapper'>
  @       <span class='cbutton' id="chat-button-preview" \
  @         title="Preview message (Shift-Enter)">&#128065;</span>
  @       <span class='cbutton' id="chat-button-search" \
  @         title="Search chat history">&#x1f50d;</span>
  @       <span class='cbutton' id="chat-button-attach" \
  @         title="Attach file to message">&#x1f4ce;</span>
  @       <span class='cbutton' id="chat-button-settings" \
  @         title="Configure chat">&#9881;</span>
  @       <span class='cbutton' id="chat-button-submit" \
  @         title="Send message (Ctrl-Enter)">&#128228;</span>
  @     </div>
  @   </div>
  @   <div id='chat-input-file-area'>
  @     <div class='file-selection-wrapper hidden'>
  @       <input type="file" name="file" id="chat-input-file">
  @     </div>
  @     <div id="chat-drop-details"></div>
  @   </div>
  @ </div>
  @ <div id='chat-user-list-wrapper' class='hidden'>
  @   <div class='legend'>
  @     <span class='help-buttonlet'>
  @      Users who have messages in the currently-loaded list.<br><br>
  @      <strong>Tap a user name</strong> to filter messages
  @      on that user and tap again to clear the filter.<br><br>
  @      <strong>Tap the title</strong> of this widget to toggle
  @      the list on and off.
  @     </span>
  @     <span>Active users (sorted by last message time)</span>
  @   </div>
  @   <div id='chat-user-list'></div>
  @ </div>
  @ <div id='chat-preview' class='hidden chat-view'>
  @  <header>Preview: (<a href='%R/md_rules' target='_blank'>markdown reference</a>)</header>
  @  <div id='chat-preview-content'></div>
  @  <div class='button-bar'><button class='action-close'>Close Preview</button></div>
  @ </div>
  @ <div id='chat-config' class='hidden chat-view'>
  @ <div id='chat-config-options'></div>
    /* ^^^populated client-side */
  @ <div class='button-bar'><button class='action-close'>Close Settings</button></div>
  @ </div>
  @ <div id='chat-search' class='hidden chat-view'>
  @   <div id='chat-search-content'></div>
      /* ^^^populated client-side */
  @   <div class='button-bar'>
  @     <button class='action-clear'>Clear results</button>
  @     <button class='action-close'>Close Search</button>
  @   </div>
  @ </div>
  @ <div id='chat-messages-wrapper' class='chat-view'>
  /* New chat messages get inserted immediately after this element */
  @ <span id='message-inject-point'></span>
  @ </div>
  fossil_free(zProjectName);
  fossil_free(zInputPlaceholder0);
  builtin_fossil_js_bundle_or("popupwidget", "storage", "fetch",
                              "pikchr", "confirmer", "copybutton",
                              NULL);
  /* Always in-line the javascript for the chat page */
  @ <script nonce="%h(style_nonce())">/* chat.c:%d(__LINE__) */
  /* We need an onload handler to ensure that window.fossil is
     initialized before the chat init code runs. */
  @ window.addEventListener('load', function(){
  @ document.body.classList.add('chat');
  @ /*^^^for skins which add their own BODY tag */;
  @ window.fossil.config.chat = {
  @   fromcli: %h(PB("cli")?"true":"false"),
  @   alertSound: "%h(zAlert)",
  @   initSize: %d(db_get_int("chat-initial-history",50)),
  @   imagesInline: !!%d(db_get_boolean("chat-inline-images",1))
  @ };
  ajax_emit_js_preview_modes(0);
  chat_emit_alert_list();
  @ }, false);
  @ </script>
  builtin_request_js("fossil.page.chat.js");
  style_finish_page();
}

/*
** Definition of repository tables used by chat
*/
static const char zChatSchema1[] =
@ CREATE TABLE repository.chat(
@   msgid INTEGER PRIMARY KEY AUTOINCREMENT,
@   mtime JULIANDAY,  -- Time for this entry - Julianday Zulu
@   lmtime TEXT,      -- Client YYYY-MM-DDZHH:MM:SS when message originally sent
@   xfrom TEXT,       -- Login of the sender
@   xmsg  TEXT,       -- Raw, unformatted text of the message
@   fname TEXT,       -- Filename of the uploaded file, or NULL
@   fmime TEXT,       -- MIMEType of the upload file, or NULL
@   mdel INT,         -- msgid of another message to delete
@   file  BLOB        -- Text of the uploaded file, or NULL
@ );
;


/*
** Create or rebuild the /chat search index. Requires that the
** repository.chat table exists. If bForce is true, it will drop the
** chatfts1 table and recreate/reindex it. If bForce is 0, it will
** only index the chat content if the chatfts1 table does not already
** exist.
*/
void chat_rebuild_index(int bForce){
  if( bForce!=0 ){
    db_multi_exec("DROP TABLE IF EXISTS chatfts1");
  }
  if( bForce!=0 || !db_table_exists("repository", "chatfts1") ){
    const int tokType = search_tokenizer_type(0);
    const char *zTokenizer = search_tokenize_arg_for_type(
      tokType==FTS5TOK_NONE ? FTS5TOK_PORTER : tokType
      /* Special case: if fts search is disabled for the main repo
      ** content, use a default tokenizer here. */
    );
    assert( zTokenizer && zTokenizer[0] );
    db_multi_exec(
      "CREATE VIRTUAL TABLE repository.chatfts1 USING fts5("
      "    xmsg, content=chat, content_rowid=msgid%s"
      ");"
      "INSERT INTO repository.chatfts1(chatfts1) VALUES('rebuild');",
      zTokenizer/*safe-for-%s*/
    );
  }
}

/*
** Make sure the repository data tables used by chat exist.  Create
** them if they do not. Set up TEMP triggers (if needed) to update the
** chatfts1 table as the chat table is updated.
*/
static void chat_create_tables(void){
  if( !db_table_exists("repository","chat") ){
    db_multi_exec(zChatSchema1/*works-like:""*/);
  }else if( !db_table_has_column("repository","chat","lmtime") ){
    if( !db_table_has_column("repository","chat","mdel") ){
      db_multi_exec("ALTER TABLE chat ADD COLUMN mdel INT");
    }
    db_multi_exec("ALTER TABLE chat ADD COLUMN lmtime TEXT");
  }
  chat_rebuild_index(0);
  db_multi_exec(
    "CREATE TEMP TRIGGER IF NOT EXISTS chat_ai AFTER INSERT ON chat BEGIN "
    "  INSERT INTO chatfts1(rowid, xmsg) VALUES(new.msgid, new.xmsg);"
    "END;"
    "CREATE TEMP TRIGGER IF NOT EXISTS chat_ad AFTER DELETE ON chat BEGIN "
    "  INSERT INTO chatfts1(chatfts1, rowid, xmsg) "
    "    VALUES('delete', old.msgid, old.xmsg);"
    "END;"
  );
}

/*
** Delete old content from the chat table.
*/
static void chat_purge(void){
   int mxCnt = db_get_int("chat-keep-count",50);
   double mxDays = atof(db_get("chat-keep-days","7"));
   double rAge;
   int msgid;
   rAge = db_double(0.0, "SELECT julianday('now')-mtime FROM chat"
                         " ORDER BY msgid LIMIT 1");
   if( rAge>mxDays ){
     msgid = db_int(0, "SELECT msgid FROM chat"
                       " ORDER BY msgid DESC LIMIT 1 OFFSET %d", mxCnt);
     if( msgid>0 ){
       Stmt s;
       db_multi_exec("PRAGMA secure_delete=ON;");
       db_prepare(&s,
             "DELETE FROM chat WHERE mtime<julianday('now')-:mxage"
             " AND msgid<%d", msgid);
       db_bind_double(&s, ":mxage", mxDays);
       db_step(&s);
       db_finalize(&s);
     }
   }
}

/*
** Sets the current CGI response type to application/json then emits a
** JSON-format error message object. If fAsMessageList is true then
** the object is output using the list format described for chat-poll,
** else it is emitted as a single object in that same format.
*/
static void chat_emit_permissions_error(int fAsMessageList){
  char * zTime = cgi_iso8601_datestamp();
  cgi_set_content_type("application/json");
  if(fAsMessageList){
    CX("{\"msgs\":[{");
  }else{
    CX("{");
  }
  CX("\"isError\": true, \"xfrom\": null,");
  CX("\"mtime\": %!j, \"lmtime\": %!j,", zTime, zTime);
  CX("\"xmsg\": \"Missing permissions or not logged in. "
     "Try <a href='%R/login?g=chat'>logging in</a>.\"");
  if(fAsMessageList){
    CX("}]}");
  }else{
    CX("}");
  }
  fossil_free(zTime);
}

/*
** WEBPAGE: chat-send hidden loadavg-exempt
**
** This page receives (via XHR) a new chat-message and/or a new file
** to be entered into the chat history.
**
** On success it responds with an empty response: the new message
** should be fetched via /chat-poll. On error, e.g. login expiry,
** it emits a JSON response in the same form as described for
** /chat-poll errors, but as a standalone object instead of a
** list of objects.
**
** Requests to this page should be POST, not GET.  POST parameters
** include:
**
**    msg        The (Markdown) text of the message to be sent
**
**    file       The content of the file attachment
**
**    lmtime     ISO-8601 formatted date-time string showing the local time
**               of the sender.
**
** At least one of the "msg" or "file" POST parameters must be provided.
*/
void chat_send_webpage(void){
  int nByte;
  const char *zMsg;
  const char *zUserName;
  login_check_credentials();
  if( 0==g.perm.Chat ) {
    chat_emit_permissions_error(0);
    return;
  }
  zUserName = (g.zLogin && g.zLogin[0]) ? g.zLogin : "nobody";
  nByte = atoi(PD("file:bytes","0"));
  zMsg = PD("msg","");
  db_begin_write();
  db_unprotect(PROTECT_READONLY);
  chat_create_tables();
  chat_purge();
  if( nByte==0 ){
    if( zMsg[0] ){
      db_multi_exec(
        "INSERT INTO chat(mtime,lmtime,xfrom,xmsg)"
        "VALUES(julianday('now'),%Q,%Q,%Q)",
        P("lmtime"), zUserName, zMsg
      );
    }
  }else{
    Stmt q;
    Blob b;
    db_prepare(&q,
        "INSERT INTO chat(mtime,lmtime,xfrom,xmsg,file,fname,fmime)"
        "VALUES(julianday('now'),%Q,%Q,%Q,:file,%Q,%Q)",
        P("lmtime"), zUserName, zMsg, PD("file:filename",""),
        PD("file:mimetype","application/octet-stream"));
    blob_init(&b, P("file"), nByte);
    db_bind_blob(&q, ":file", &b);
    db_step(&q);
    db_finalize(&q);
    blob_reset(&b);
  }
  db_commit_transaction();
  db_protect_pop();
}

/*
** This routine receives raw (user-entered) message text and
** transforms it into HTML that is safe to insert using innerHTML. As
** of 2021-09-19, it does so by using wiki_convert() or
** markdown_to_html() to convert wiki/markdown-formatted zMsg to HTML.
**
** Space to hold the returned string is obtained from fossil_malloc()
** and must be freed by the caller.
*/
static char *chat_format_to_html(const char *zMsg, int isWiki){
  Blob out;
  blob_init(&out, "", 0);
  if( zMsg==0 || zMsg[0]==0 ){
    /* No-op */
  }else if( isWiki ){
    /* Used for chat-timeline-user.  The zMsg is text/x-fossil-wiki. */
    Blob bIn;
    blob_init(&bIn, zMsg, (int)strlen(zMsg));
    wiki_convert(&bIn, &out, WIKI_INLINE);
  }else{
    /* The common case:  zMsg is text/x-markdown */
    Blob bIn;
    blob_init(&bIn, zMsg, (int)strlen(zMsg));
    markdown_to_html(&bIn, NULL, &out);
  }
  return blob_str(&out);
}

/*
** COMMAND: test-chat-formatter
**
** Usage: %fossil test-chat-formatter ?OPTIONS? STRING ...
**
** Transform each argument string into HTML that will display the
** chat message.  This is used to test the formatter and to verify
** that a malicious message text will not cause HTML or JS injection
** into the chat display in a browser.
**
** Options:
**
**     -w|--wiki     Assume fossil wiki format instead of markdown
*/
void chat_test_formatter_cmd(void){
  int i;
  char *zOut;
  int const isWiki = find_option("w","wiki",0)!=0;
  db_find_and_open_repository(0,0);
  g.perm.Hyperlink = 1;
  for(i=2; i<g.argc; i++){
    zOut = chat_format_to_html(g.argv[i], isWiki);
    fossil_print("[%d]: %s\n", i-1, zOut);
    fossil_free(zOut);
  }
}

/*
** The SQL statement passed as the first argument should return zero or
** more rows of data, each of which represents a single message from the
** "chat" table. The rows returned should be similar to those returned
** by:
**
**     SELECT msgid, 
**            datetime(mtime), 
**            xfrom, 
**            xmsg, 
**            octet_length(file),"
**            fname, 
**            fmime, 
**            mdel, 
**            lmtime
**     FROM chat;
**
** This function loops through all rows returned by statement p, adding
** a record to the JSON stored in argument pJson for each. See comments 
** above function chat_poll_webpage() for a description of the JSON records
** added to pJson.
*/
static int chat_poll_rowstojson(
  Stmt *p,                        /* Statement to read rows from */
  int bRaw,                       /* True to return raw format xmsg */
  Blob *pJson                     /* Append json array entries here */
){
  int cnt = 0;
  const char *zChatUser = db_get("chat-timeline-user",0);
  while( db_step(p)==SQLITE_ROW ){
    int isWiki = 0;             /* True if chat message is x-fossil-wiki */
    int id = db_column_int(p, 0);
    const char *zDate = db_column_text(p, 1);
    const char *zFrom = db_column_text(p, 2);
    const char *zRawMsg = db_column_text(p, 3);
    int nByte = db_column_int(p, 4);
    const char *zFName = db_column_text(p, 5);
    const char *zFMime = db_column_text(p, 6);
    int iToDel = db_column_int(p, 7);
    const char *zLMtime = db_column_text(p, 8);
    char *zMsg;
    if(cnt++){
      blob_append(pJson, ",\n", 2);
    }
    blob_appendf(pJson, "{\"msgid\":%d,", id);
    blob_appendf(pJson, "\"mtime\":\"%.10sT%sZ\",", zDate, zDate+11);
    if( zLMtime && zLMtime[0] ){
      blob_appendf(pJson, "\"lmtime\":%!j,", zLMtime);
    }
    blob_append(pJson, "\"xfrom\":", -1);
    if(zFrom){
      blob_appendf(pJson, "%!j,", zFrom);
      isWiki = fossil_strcmp(zFrom,zChatUser)==0;
    }else{
      /* see https://fossil-scm.org/forum/forumpost/e0be0eeb4c */
      blob_appendf(pJson, "null,");
      isWiki = 0;
    }
    blob_appendf(pJson, "\"uclr\":%!j,",
        isWiki ? "transparent" : user_color(zFrom ? zFrom : "nobody"));

    if(bRaw){
      blob_appendf(pJson, "\"xmsg\":%!j,", zRawMsg);
    }else{
      zMsg = chat_format_to_html(zRawMsg ? zRawMsg : "", isWiki);
      blob_appendf(pJson, "\"xmsg\":%!j,", zMsg);
      fossil_free(zMsg);
    }

    if( nByte==0 ){
      blob_appendf(pJson, "\"fsize\":0");
    }else{
      blob_appendf(pJson, "\"fsize\":%d,\"fname\":%!j,\"fmime\":%!j",
          nByte, zFName, zFMime);
    }

    if( iToDel ){
      blob_appendf(pJson, ",\"mdel\":%d}", iToDel);
    }else{
      blob_append(pJson, "}", 1);
    }
  }
  db_reset(p);

  return cnt;
}

/*
** WEBPAGE: chat-poll hidden loadavg-exempt
**
** The chat page generated by /chat using an XHR to this page to
** request new chat content.  A typical invocation is:
**
**     /chat-poll/N
**     /chat-poll?name=N
**
** The "name" argument should begin with an integer which is the largest
** "msgid" that the chat page currently holds. If newer content is
** available, this routine returns that content straight away. If no new
** content is available, this webpage blocks until the new content becomes
** available.  In this way, the system implements "hanging-GET" or "long-poll"
** style event notification. If no new content arrives after a delay of
** approximately chat-poll-timeout seconds (default: 420), then reply is
** sent with an empty "msg": field.
**
** If N is negative, then the return value is the N most recent messages.
** Hence a request like /chat-poll/-100 can be used to initialize a new
** chat session to just the most recent messages.
**
** Some webservers (althttpd) do not allow a term of the URL path to
** begin with "-".  Then /chat-poll/-100 cannot be used.  Instead you
** have to say "/chat-poll?name=-100".
**
** If the integer parameter "before" is passed in, it is assumed that
** the client is requesting older messages, up to (but not including)
** that message ID, in which case the next-oldest "n" messages
** (default=chat-initial-history setting, equivalent to n=0) are
** returned (negative n fetches all older entries). The client then
** needs to take care to inject them at the end of the history rather
** than the same place new messages go.
**
** If "before" is provided, "name" is ignored.
**
** If "raw" is provided, the "xmsg" text is sent back as-is, in
** markdown format, rather than being HTML-ized. This is not used or
** supported by fossil's own chat client but is intended for 3rd-party
** clients. (Specifically, for Brad Harder's curses-based client.)
**
** The reply from this webpage is JSON that describes the new content.
** Format of the json:
**
** |    {
** |      "msgs":[
** |        {
** |           "msgid": integer // message id
** |           "mtime": text    // When sent: YYYY-MM-DDTHH:MM:SSZ
** |           "lmtime: text    // Sender's client-side YYYY-MM-DDTHH:MM:SS
** |           "xfrom": text    // Login name of sender
** |           "uclr":  text    // Color string associated with the user
** |           "xmsg":  text    // HTML text of the message
** |           "fsize": integer // file attachment size in bytes
** |           "fname": text    // Name of file attachment
** |           "fmime": text    // MIME-type of file attachment
** |           "mdel":  integer // message id of prior message to delete
** |        }
** |      ]
** |    }
**
** The "fname" and "fmime" fields are only present if "fsize" is greater
** than zero.  The "xmsg" field may be an empty string if "fsize" is zero.
**
** The "msgid" values will be in increasing order.
**
** The "mdel" will only exist if "xmsg" is an empty string and "fsize" is zero.
**
** The "lmtime" value might be unknown, in which case it is omitted.
**
** The messages are ordered oldest first unless "before" is provided, in which
** case they are sorted newest first (to facilitate the client-side UI update).
**
** As a special case, if this routine encounters an error, e.g. the user's
** permissions cannot be verified because their login cookie expired, the
** request returns a slightly modified structure:
**
** |    {
** |      "msgs":[
** |        {
** |          "isError": true,
** |          "xfrom": null,
** |          "xmsg": "error details"
** |          "mtime": as above,
** |          "ltime": same as mtime
** |        }
** |      ]
** |    }
**
** If the client gets such a response, it should display the message
** in a prominent manner and then stop polling for new messages.
*/
void chat_poll_webpage(void){
  Blob json;                  /* The json to be constructed and returned */
  sqlite3_int64 dataVersion;  /* Data version.  Used for polling. */
  const int iDelay = 1000;    /* Delay until next poll (milliseconds) */
  int nDelay;                 /* Maximum delay.*/
  int msgid = atoi(PD("name","0"));
  const int msgBefore = atoi(PD("before","0"));
  int nLimit = msgBefore>0 ? atoi(PD("n","0")) : 0;
  const int bRaw = P("raw")!=0;

  Blob sql = empty_blob;
  Stmt q1;
  nDelay = db_get_int("chat-poll-timeout",420);  /* Default about 7 minutes */
  login_check_credentials();
  if( !g.perm.Chat ) {
    chat_emit_permissions_error(1);
    return;
  }
  chat_create_tables();
  cgi_set_content_type("application/json");
  dataVersion = db_int64(0, "PRAGMA data_version");
  blob_append_sql(&sql,
    "SELECT msgid, datetime(mtime), xfrom, xmsg, octet_length(file),"
    "       fname, fmime, %s, lmtime"
    "  FROM chat ",
    msgBefore>0 ? "0 as mdel" : "mdel");
  if( msgid<=0 || msgBefore>0 ){
    db_begin_write();
    chat_purge();
    db_commit_transaction();
  }
  if(msgBefore>0){
    if(0==nLimit){
      nLimit = db_get_int("chat-initial-history",50);
    }
    blob_append_sql(&sql,
      " WHERE msgid<%d"
      " ORDER BY msgid DESC "
      "LIMIT %d",
      msgBefore, nLimit>0 ? nLimit : -1
    );
  }else{
    if( msgid<0 ){
      msgid = db_int(0,
            "SELECT msgid FROM chat WHERE mdel IS NOT true"
            " ORDER BY msgid DESC LIMIT 1 OFFSET %d", -msgid);
    }
    blob_append_sql(&sql,
      " WHERE msgid>%d"
      " ORDER BY msgid",
      msgid
    );
  }
  db_prepare(&q1, "%s", blob_sql_text(&sql));
  blob_reset(&sql);
  blob_init(&json, "{\"msgs\":[\n", -1);
  while( nDelay>0 ){
    int cnt = chat_poll_rowstojson(&q1, bRaw, &json);
    if( cnt || msgBefore>0 ){
      break;
    }
    sqlite3_sleep(iDelay); nDelay--;
    while( nDelay>0 ){
      sqlite3_int64 newDataVers = db_int64(0,"PRAGMA repository.data_version");
      if( newDataVers!=dataVersion ){
        dataVersion = newDataVers;
        break;
      }
      sqlite3_sleep(iDelay); nDelay--;
    }
  } /* Exit by "break" */
  db_finalize(&q1);
  blob_append(&json, "\n]}", 3);
  cgi_set_content(&json);
  return;
}


/*
** WEBPAGE: chat-query hidden loadavg-exempt
*/
void chat_query_webpage(void){
  Blob json;                  /* The json to be constructed and returned */
  Blob sql = empty_blob;
  Stmt q1;
  int nLimit = atoi(PD("n","500"));
  int iFirst = atoi(PD("i","0"));
  const char *zQuery = PD("q", "");
  i64 iMin = 0;
  i64 iMax = 0;

  login_check_credentials();
  if( !g.perm.Chat ) {
    chat_emit_permissions_error(1);
    return;
  }
  chat_create_tables();
  cgi_set_content_type("application/json");

  if( zQuery[0] ){
    iMax = db_int64(0, "SELECT max(msgid) FROM chat");
    iMin = db_int64(0, "SELECT min(msgid) FROM chat");
    if( '#'==zQuery[0] ){
      /* Assume we're looking for an exact msgid match. */
      ++zQuery;
      blob_append_sql(&sql,
        "SELECT msgid, datetime(mtime), xfrom, "
        "  xmsg, octet_length(file), fname, fmime, mdel, lmtime "
        "  FROM chat WHERE msgid=+%Q",
        zQuery
      );
    }else{
      char * zPat = search_simplify_pattern(zQuery);
      blob_append_sql(&sql,
        "SELECT * FROM ("
        "SELECT c.msgid, datetime(c.mtime), c.xfrom, "
        "  highlight(chatfts1, 0, '<span class=\"match\">', '</span>'), "
        "  octet_length(c.file), c.fname, c.fmime, c.mdel, c.lmtime "
        "  FROM chatfts1(%Q) f, chat c "
        "  WHERE f.rowid=c.msgid"
        "  ORDER BY f.rowid DESC LIMIT %d"
        ") ORDER BY 1 ASC", zPat, nLimit
      );
      fossil_free(zPat);
    }
  }else{
    blob_append_sql(&sql,
        "SELECT msgid, datetime(mtime), xfrom, "
        "  xmsg, octet_length(file), fname, fmime, mdel, lmtime"
        "  FROM chat WHERE msgid>=%d LIMIT %d",
        iFirst, nLimit
    );
  }

  db_prepare(&q1, "%s", blob_sql_text(&sql));
  blob_reset(&sql);
  blob_init(&json, "{\"msgs\":[\n", -1);
  chat_poll_rowstojson(&q1, 0, &json);
  db_finalize(&q1);
  blob_appendf(&json, "\n], \"first\":%lld, \"last\":%lld}", iMin, iMax);
  cgi_set_content(&json);
  return;
}

/*
** WEBPAGE: chat-fetch-one hidden loadavg-exempt
**
** /chat-fetch-one/N
**
** Fetches a single message with the given ID, if available.
**
** Options:
**
**   raw = the xmsg field will be returned unparsed.
**
** Response is either a single object in the format returned by
** /chat-poll (without the wrapper array) or a JSON-format error
** response, as documented for ajax_route_error().
*/
void chat_fetch_one(void){
  Blob json = empty_blob;   /* The json to be constructed and returned */
  const int fRaw = PD("raw",0)!=0;
  const int msgid = atoi(PD("name","0"));
  const char *zChatUser;
  int isWiki;
  Stmt q;
  login_check_credentials();
  if( !g.perm.Chat ) {
    chat_emit_permissions_error(0);
    return;
  }
  zChatUser = db_get("chat-timeline-user",0);
  chat_create_tables();
  cgi_set_content_type("application/json");
  db_prepare(&q,
    "SELECT datetime(mtime), xfrom, xmsg, octet_length(file),"
    "       fname, fmime, lmtime"
    "  FROM chat WHERE msgid=%d AND mdel IS NULL",
    msgid);
  if(SQLITE_ROW==db_step(&q)){
    const char *zDate = db_column_text(&q, 0);
    const char *zFrom = db_column_text(&q, 1);
    const char *zRawMsg = db_column_text(&q, 2);
    const int nByte = db_column_int(&q, 3);
    const char *zFName = db_column_text(&q, 4);
    const char *zFMime = db_column_text(&q, 5);
    const char *zLMtime = db_column_text(&q, 7);
    blob_appendf(&json,"{\"msgid\": %d,", msgid);

    blob_appendf(&json, "\"mtime\":\"%.10sT%sZ\",", zDate, zDate+11);
    if( zLMtime && zLMtime[0] ){
      blob_appendf(&json, "\"lmtime\":%!j,", zLMtime);
    }
    blob_append(&json, "\"xfrom\":", -1);
    if(zFrom){
      blob_appendf(&json, "%!j,", zFrom);
      isWiki = fossil_strcmp(zFrom, zChatUser)==0;
    }else{
      /* see https://fossil-scm.org/forum/forumpost/e0be0eeb4c */
      blob_appendf(&json, "null,");
      isWiki = 0;
    }
    blob_appendf(&json, "\"uclr\":%!j,",
                 isWiki ? "transparent" : user_color(zFrom ? zFrom : "nobody"));
    blob_append(&json,"\"xmsg\":", 7);
    if(fRaw){
      blob_appendf(&json, "%!j,", zRawMsg);
    }else{
      char * zMsg = chat_format_to_html(zRawMsg ? zRawMsg : "", isWiki);
      blob_appendf(&json, "%!j,", zMsg);
      fossil_free(zMsg);
    }
    if( nByte==0 ){
      blob_appendf(&json, "\"fsize\":0");
    }else{
      blob_appendf(&json, "\"fsize\":%d,\"fname\":%!j,\"fmime\":%!j",
                   nByte, zFName, zFMime);
    }
    blob_append(&json,"}",1);
    cgi_set_content(&json);
  }else{
    ajax_route_error(404,"Chat message #%d not found.", msgid);
  }
  db_finalize(&q);
}

/*
** WEBPAGE: chat-download hidden loadavg-exempt
**
** Download the CHAT.FILE attachment associated with a single chat
** entry.  The "name" query parameter begins with an integer that
** identifies the particular chat message. The integer may be followed
** by a / and a filename, which will (A) indicate to the browser to
** use the indicated name when saving the file and (B) be used to
** guess the mimetype in some particular cases involving the "render"
** flag.
**
** If the "render" URL parameter is provided, the blob has a size
** greater than zero, and blob meets one of the following conditions
** then the fossil-rendered form of that content is returned, rather
** than the original:
**
** - Mimetype is text/x-markdown or text/markdown: emit HTML.
**
** - Mimetype is text/x-fossil-wiki or P("name") ends with ".wiki":
**   emit HTML.
**
** - Mimetype is text/x-pikchr or P("name") ends with ".pikchr": emit
**   image/svg+xml if rendering succeeds or text/html if rendering
**   fails.
*/
void chat_download_webpage(void){
  int msgid;
  int bCheckedMimetype = 0;  /* true to bypass the text/... mimetype
                             ** check at the end */
  Blob r;                    /* file content */
  const char *zMime;         /* file mimetype */
  const char *zName = PD("name","0");
  login_check_credentials();
  if( !g.perm.Chat ){
    style_header("Chat Not Authorized");
    @ <h1>Not Authorized</h1>
    @ <p>You do not have permission to use the chatroom on this
    @ repository.</p>
    style_finish_page();
    return;
  }
  chat_create_tables();
  msgid = atoi(zName);
  blob_zero(&r);
  zMime = db_text(0, "SELECT fmime FROM chat wHERE msgid=%d", msgid);
  if( zMime==0 ) return;
  db_blob(&r, "SELECT file FROM chat WHERE msgid=%d", msgid);
  if( r.nUsed>0 && P("render")!=0 ){
    /* Maybe return fossil-rendered form of the content. */
    Blob r2 = BLOB_INITIALIZER;    /* output target for rendering */
    const char * zMime2 = 0;       /* adjusted response mimetype */
    if(fossil_strcmp(zMime, "text/x-markdown")==0
       /* Firefox uploads md files with the mimetype text/markdown */
       || fossil_strcmp(zMime, "text/markdown")==0){
      markdown_to_html(&r, 0, &r2);
      safe_html(&r2);
      zMime2 = "text/html";
      bCheckedMimetype = 1;
    }else if(fossil_strcmp(zMime, "text/x-fossil-wiki")==0
             || sqlite3_strglob("*.wiki", zName)==0){
      /* .wiki files get uploaded as application/octet-stream */
      wiki_convert(&r, &r2, 0);
      zMime2 = "text/html";
      bCheckedMimetype = 1;
    }else if(fossil_strcmp(zMime, "text/x-pikchr")==0
             || sqlite3_strglob("*.pikchr",zName)==0){
      /* .pikchr files get uploaded as application/octet-stream */
      const char *zPikchr = blob_str(&r);
      int w = 0, h = 0;
      char *zOut = pikchr(zPikchr, "pikchr", 0, &w, &h);
      if(zOut){
        blob_append(&r2, zOut, -1);
      }
      zMime2 = w>0 ? "image/svg+xml" : "text/html";
      free(zOut);
      bCheckedMimetype = 1;
    }
    if(r2.aData!=0){
      blob_swap(&r, &r2);
      blob_reset(&r2);
      zMime = zMime2;
    }
  }
  if( bCheckedMimetype==0 && sqlite3_strglob("text/*", zMime)==0 ){
    /* The problem: both Chrome and Firefox upload *.patch with
    ** the mimetype text/x-patch, whereas we very often use that
    ** name glob for fossil-format patches. That causes such files
    ** to attempt to render in the browser when clicked via
    ** download links in chat.
    **
    ** The workaround: */
    if( looks_like_binary(&r) ){
      zMime = "application/octet-stream";
    }
  }
  cgi_set_content_type(zMime);
  cgi_set_content(&r);
}


/*
** WEBPAGE: chat-delete hidden loadavg-exempt
**
** Delete the chat entry identified by the name query parameter.
** Invoking fetch("chat-delete/"+msgid) from javascript in the client
** will delete a chat entry from the CHAT table.
**
** This routine both deletes the identified chat entry and also inserts
** a new entry with the current timestamp and with:
**
**   *  xmsg = NULL
**
**   *  file = NULL
**
**   *  mdel = The msgid of the row that was deleted
**
** This new entry will then be propagated to all listeners so that they
** will know to delete their copies of the message too.
*/
void chat_delete_webpage(void){
  int mdel;
  char *zOwner;
  login_check_credentials();
  if( !g.perm.Chat ) return;
  chat_create_tables();
  mdel = atoi(PD("name","0"));
  zOwner = db_text(0, "SELECT xfrom FROM chat WHERE msgid=%d", mdel);
  if( zOwner==0 ) return;
  if( fossil_strcmp(zOwner, g.zLogin)!=0 && !g.perm.Admin ) return;
  db_multi_exec(
    "PRAGMA secure_delete=ON;\n"
    "BEGIN;\n"
    "DELETE FROM chat WHERE msgid=%d;\n"
    "INSERT INTO chat(mtime, xfrom, mdel)"
    " VALUES(julianday('now'), %Q, %d);\n"
    "COMMIT;",
    mdel, g.zLogin, mdel
  );
}

/*
** WEBPAGE: chat-backup hidden
**
** Download an SQLite database containing all chat content with a
** message-id larger than the "msgid" query parameter.  Setup
** privilege is required to use this URL.
**
** This is used to implement the "fossil chat pull" command.
*/
void chat_backup_webpage(void){
  int msgid;
  unsigned char *pDb = 0;
  sqlite3_int64 szDb = 0;
  Blob chatDb;
  login_check_credentials();
  if( !g.perm.Setup ) return;
  msgid = atoi(PD("msgid","0"));
  db_multi_exec(
    "ATTACH ':memory:' AS mem1;\n"
    "PRAGMA mem1.page_size=512;\n"
    "CREATE TABLE mem1.chat AS SELECT * FROM repository.chat WHERE msgid>%d;\n",
    msgid
  );
  pDb = sqlite3_serialize(g.db, "mem1", &szDb, 0);
  if( pDb==0 ){
    fossil_fatal("Out of memory");
  }
  blob_init(&chatDb, (const char*)pDb, (int)szDb);
  cgi_set_content_type("application/x-sqlite3");
  cgi_set_content(&chatDb);
}

/*
** SQL Function: chat_msg_from_event(TYPE,OBJID,USER,MSG)
**
** This function returns HTML text that describes an entry from the EVENT
** table (that is, a timeline event) for display in chat.  Parameters:
**
**    TYPE         The event type.  'ci', 'w', 't', 'g', and so forth
**    OBJID        EVENT.OBJID
**    USER         coalesce(EVENT.EUSER,EVENT.USER)
**    MSG          coalesce(EVENT.ECOMMENT, EVENT.COMMENT)
**
** This function is intended to be called by the temp.chat_trigger1 trigger
** which is created by alert_create_trigger() routine.
*/
void chat_msg_from_event(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  const char *zType = (const char*)sqlite3_value_text(argv[0]);
  int rid = sqlite3_value_int(argv[1]);
  const char *zUser = (const char*)sqlite3_value_text(argv[2]);
  const char *zMsg = (const char*)sqlite3_value_text(argv[3]);
  char *zRes = 0;

  if( zType==0 || zUser==0 || zMsg==0 ) return;
  if( zType[0]=='c' ){
    /* Check-ins */
    char *zBranch;
    char *zUuid;

    zBranch = db_text(0,
       "SELECT value FROM tagxref"
       " WHERE tagxref.rid=%d"
       "   AND tagxref.tagid=%d"
       "   AND tagxref.tagtype>0",
       rid, TAG_BRANCH);
    zUuid = db_text(0, "SELECT uuid FROM blob WHERE rid=%d", rid);
    zRes = mprintf("%W (check-in: <a href='%R/info/%S'>%S</a>, "
                   "user: <a href='%R/timeline?u=%t&c=%S'>%h</a>, "
                   "branch: <a href='%R/timeline?r=%t&c=%S'>%h</a>)",
             zMsg,
             zUuid, zUuid,
             zUser, zUuid, zUser,
             zBranch, zUuid, zBranch
    );
    fossil_free(zBranch);
    fossil_free(zUuid);
  }else if( zType[0]=='w' ){
    /* Wiki page changes */
    char *zUuid = rid_to_uuid(rid);
    wiki_hyperlink_override(zUuid);
    if( zMsg[0]=='-' ){
      zRes = mprintf("Delete wiki page <a href='%R/whistory?name=%t'>%h</a>",
         zMsg+1, zMsg+1);
    }else if( zMsg[0]=='+' ){
      zRes = mprintf("Added wiki page <a href='%R/whistory?name=%t'>%h</a>",
         zMsg+1, zMsg+1);
    }else if( zMsg[0]==':' ){
      zRes = mprintf("<a href='%R/wdiff?id=%!S'>Changes</a> to wiki page "
                     "<a href='%R/whistory?name=%t'>%h</a>",
         zUuid, zMsg+1, zMsg+1);
    }else{
      zRes = mprintf("%W", zMsg);
    }
    wiki_hyperlink_override(0);
    fossil_free(zUuid);
  }else if( zType[0]=='f' ){
    /* Forum changes */
    char *zUuid = rid_to_uuid(rid);
    zRes = mprintf( "%W (artifact: <a href='%R/info/%S'>%S</a>, "
                    "user: <a href='%R/timeline?u=%t&c=%S'>%h</a>)",
                    zMsg, zUuid, zUuid, zUser, zUuid, zUser);
    fossil_free(zUuid);
  }else{
    /* Anything else */
    zRes = mprintf("%W", zMsg);
  }
  if( zRes ){
    sqlite3_result_text(context, zRes, -1, fossil_free);
  }
}


/*
** COMMAND: chat
**
** Usage: %fossil chat [SUBCOMMAND] [--remote URL] [ARGS...]
**
** This command performs actions associated with the /chat instance
** on the default remote Fossil repository (the Fossil repository whose
** URL shows when you run the "fossil remote" command) or to the URL
** specified by the --remote option.  If there is no default remote
** Fossil repository and the --remote option is omitted, then this
** command fails with an error.
**
** Subcommands:
**
** > fossil chat
**
**      When there is no SUBCOMMAND (when this command is simply "fossil chat")
**      the response is to bring up a web-browser window to the chatroom
**      on the default system web-browser.  You can accomplish the same by
**      typing the appropriate URL into the web-browser yourself.  This
**      command is merely a convenience for command-line oriented people.
**
** > fossil chat pull
**
**      Copy chat content from the server down into the local clone,
**      as a backup or archive.  Setup privilege is required on the server.
**
**        --all                  Download all chat content. Normally only
**                               previously undownloaded content is retrieved.
**        --debug                Additional debugging output
**        --out DATABASE         Store CHAT table in separate database file
**                               DATABASE rather that adding to local clone
**        --unsafe               Allow the use of unencrypted http://
**
** > fossil chat send [ARGUMENTS]
**
**      This command sends a new message to the chatroom.  The message
**      to be sent is determined by arguments as follows:
**
**        -f|--file FILENAME     File to attach to the message
**        --as FILENAME2         Causes --file FILENAME to be sent with
**                               the attachment name FILENAME2
**        -m|--message TEXT      Text of the chat message
**        --remote URL           Send to this remote URL
**        --unsafe               Allow the use of unencrypted http://
**
** > fossil chat url
**
**      Show the default URL used to access the chat server.
**
** Additional subcommands may be added in the future.
*/
void chat_command(void){
  const char *zUrl = find_option("remote",0,1);
  int urlFlags = 0;
  int isDefaultUrl = 0;
  int i;

  db_find_and_open_repository(0,0);
  if( zUrl ){
    urlFlags = URL_PROMPT_PW;
  }else{
    zUrl = db_get("last-sync-url",0);
    if( zUrl==0 ){
      fossil_fatal("no \"remote\" repository defined");
    }else{
      isDefaultUrl = 1;
    }
  }
  url_parse(zUrl, urlFlags);
  if( g.url.isFile || g.url.isSsh ){
    fossil_fatal("chat only works for http:// and https:// URLs");
  }
  i = (int)strlen(g.url.path);
  while( i>0 && g.url.path[i-1]=='/' ) i--;
  if( g.url.port==g.url.dfltPort ){
    zUrl = mprintf(
      "%s://%T%.*T",
      g.url.protocol, g.url.name, i, g.url.path
    );
  }else{
    zUrl = mprintf(
      "%s://%T:%d%.*T",
      g.url.protocol, g.url.name, g.url.port, i, g.url.path
    );
  }
  if( g.argc==2 ){
    const char *zBrowser = fossil_web_browser();
    char *zCmd;
    verify_all_options();
    if( zBrowser==0 ) return;
#ifdef _WIN32
    zCmd = mprintf("%s %s/chat?cli &", zBrowser, zUrl);
#else
    zCmd = mprintf("%s \"%s/chat?cli\" &", zBrowser, zUrl);
#endif
    fossil_system(zCmd);
  }else if( strcmp(g.argv[2],"send")==0 ){
    const char *zFilename = find_option("file","f",1);
    const char *zAs = find_option("as",0,1);
    const char *zMsg = find_option("message","m",1);
    int allowUnsafe = find_option("unsafe",0,0)!=0;
    const int mFlags = HTTP_GENERIC | HTTP_QUIET | HTTP_NOCOMPRESS;
    int i;
    const char *zPw;
    char *zLMTime;
    Blob up, down, fcontent;
    char zBoundary[80];
    sqlite3_uint64 r[3];
    if( zFilename==0 && zMsg==0 ){
      fossil_fatal("must have --message or --file or both");
    }
    if( !g.url.isHttps && !allowUnsafe ){
      fossil_fatal("URL \"%s\" is unencrypted. Use https:// instead", zUrl);
    }
    verify_all_options();
    if( g.argc>3 ){
      fossil_fatal("unknown extra argument: \"%s\"", g.argv[3]);
    }
    i = (int)strlen(g.url.path);
    while( i>0 && g.url.path[i-1]=='/' ) i--;
    g.url.path = mprintf("%.*s/chat-send", i, g.url.path);
    blob_init(&up, 0, 0);
    blob_init(&down, 0, 0);
    sqlite3_randomness(sizeof(r),r);
    sqlite3_snprintf(sizeof(zBoundary),zBoundary,
                     "--------%016llu%016llu%016llu", r[0], r[1], r[2]);
    blob_appendf(&up, "%s", zBoundary);
    zLMTime = db_text(0,
              "SELECT strftime('%%Y-%%m-%%dT%%H:%%M:%%S','now','localtime')");
    if( zLMTime ){
      blob_appendf(&up,"\r\nContent-Disposition: form-data; name=\"lmtime\"\r\n"
                       "\r\n%z\r\n%s", zLMTime, zBoundary);
    }
    if( g.url.user && g.url.user[0] ){
      blob_appendf(&up,"\r\nContent-Disposition: form-data; name=\"resid\"\r\n"
                       "\r\n%z\r\n%s", obscure(g.url.user), zBoundary);
    }
    zPw = g.url.passwd;
    if( zPw==0 && isDefaultUrl ) zPw = unobscure(db_get("last-sync-pw", 0));
    if( zPw && zPw[0] ){
      blob_appendf(&up,"\r\nContent-Disposition: form-data; name=\"token\"\r\n"
                       "\r\n%z\r\n%s", obscure(zPw), zBoundary);
    }
    if( zMsg && zMsg[0] ){
      blob_appendf(&up,"\r\nContent-Disposition: form-data; name=\"msg\"\r\n"
                       "\r\n%s\r\n%s", zMsg, zBoundary);
    }
    if( zFilename && blob_read_from_file(&fcontent, zFilename, ExtFILE)>0 ){
      char *zFN = mprintf("%s", file_tail(zAs ? zAs : zFilename));
      int i;
      const char *zMime = mimetype_from_name(zFN);
      for(i=0; zFN[i]; i++){
        char c = zFN[i];
        if( fossil_isalnum(c) ) continue;
        if( c=='.' ) continue;
        if( c=='-' ) continue;
        zFN[i] = '_';
      }
      blob_appendf(&up,"\r\nContent-Disposition: form-data; name=\"file\";"
                       " filename=\"%s\"\r\n", zFN);
      blob_appendf(&up,"Content-Type: %s\r\n\r\n", zMime);
      blob_append(&up, fcontent.aData, fcontent.nUsed);
      blob_appendf(&up,"\r\n%s", zBoundary);
    }
    blob_append(&up,"--\r\n", 4);
    http_exchange(&up, &down, mFlags, 4, "multipart/form-data");
    blob_reset(&up);
    if( sqlite3_strglob("{\"isError\": true,*", blob_str(&down))==0 ){
      if( strstr(blob_str(&down), "not logged in")!=0 ){
        fossil_print("ERROR: username and/or password is incorrect\n");
      }else{
        fossil_print("ERROR: %s\n", blob_str(&down));
      }
      fossil_fatal("unable to send the chat message");
    }
    blob_reset(&down);
  }else if( strcmp(g.argv[2],"pull")==0 ){
    /* Pull the CHAT table from the default server down into the repository
    ** here on the local side */
    int allowUnsafe = find_option("unsafe",0,0)!=0;
    int bDebug = find_option("debug",0,0)!=0;
    const char *zOut = find_option("out",0,1);
    int bAll = find_option("all",0,0)!=0;
    int mFlags = HTTP_GENERIC | HTTP_QUIET | HTTP_NOCOMPRESS;
    int msgid;
    Blob reqUri;    /* The REQUEST_URI:  .../chat-backup?msgid=... */
    char *zObs;
    const char *zPw;
    Blob up, down;
    int nChat;
    int rc;
    verify_all_options();
    chat_create_tables();
    msgid = bAll ? 0 : db_int(0,"SELECT max(msgid) FROM chat");
    if( !g.url.isHttps && !allowUnsafe ){
      fossil_fatal("URL \"%s\" is unencrypted. Use https:// instead", zUrl);
    }
    blob_init(&reqUri, g.url.path, -1);
    blob_appendf(&reqUri, "/chat-backup?msgid=%d", msgid);
    if( g.url.user && g.url.user[0] ){
      zObs = obscure(g.url.user);
      blob_appendf(&reqUri, "&resid=%t", zObs);
      fossil_free(zObs);
    }
    zPw = g.url.passwd;
    if( zPw==0 && isDefaultUrl ){
      zPw = unobscure(db_get("last-sync-pw", 0));
      if( zPw==0 ){
        /* Can happen if "remember password" is not used. */
        g.url.flags |= URL_PROMPT_PW;
        url_prompt_for_password();
        zPw = g.url.passwd;
      }
    }
    if( zPw && zPw[0] ){
      zObs = obscure(zPw);
      blob_appendf(&reqUri, "&token=%t", zObs);
      fossil_free(zObs);
    }
    g.url.path = blob_str(&reqUri);
    if( bDebug ){
      fossil_print("REQUEST_URI: %s\n", g.url.path);
      mFlags &= ~HTTP_QUIET;
      mFlags |= HTTP_VERBOSE;
    }
    blob_init(&up, 0, 0);
    blob_init(&down, 0, 0);
    http_exchange(&up, &down, mFlags, 4, 0);
    if( zOut ){
      blob_write_to_file(&down, zOut);
      fossil_print("Chat database at %s is %d bytes\n", zOut, blob_size(&down));
    }else{
      db_multi_exec("ATTACH ':memory:' AS chatbu;");
      if( g.fSqlTrace ){
        fossil_trace("-- deserialize(\"chatbu\", pData, %d);\n",
                     blob_size(&down));
      }
      rc = sqlite3_deserialize(g.db, "chatbu",
                            (unsigned char*)blob_buffer(&down),
                             blob_size(&down), blob_size(&down), 0);
      if( rc ){
        fossil_fatal("cannot open patch database: %s", sqlite3_errmsg(g.db));
      }
      nChat = db_int(0, "SELECT count(*) FROM chatbu.chat");
      fossil_print("Got %d new records, %d bytes\n", nChat, blob_size(&down));
      db_multi_exec(
        "REPLACE INTO repository.chat(msgid,mtime,lmtime,xfrom,xmsg,"
                                     "fname,fmime,mdel,file)"
        " SELECT msgid,mtime,lmtime,xfrom,xmsg,fname,fmime,mdel,file"
          " FROM chatbu.chat;"
      );
    }
  }else if( strcmp(g.argv[2],"url")==0 ){
    /* Show the URL to access chat. */
    fossil_print("%s/chat\n", zUrl);
  }else{
    fossil_fatal("no such subcommand \"%s\".  Use --help for help", g.argv[2]);
  }
}
