/*
** Copyright (c) 2018 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 generate the user forum.
*/
#include "config.h"
#include <assert.h>
#include "forum.h"

/*
** Default to using Markdown markup
*/
#define DEFAULT_FORUM_MIMETYPE  "text/x-markdown"

#if INTERFACE
/*
** Each instance of the following object represents a single message -
** either the initial post, an edit to a post, a reply, or an edit to
** a reply.
*/
struct ForumPost {
  int fpid;              /* rid for this post */
  int sid;               /* Serial ID number */
  int rev;               /* Revision number */
  char *zUuid;           /* Artifact hash */
  char *zDisplayName;    /* Name of user who wrote this post */
  double rDate;          /* Date for this post */
  ForumPost *pIrt;       /* This post replies to pIrt */
  ForumPost *pEditHead;  /* Original, unedited post */
  ForumPost *pEditTail;  /* Most recent edit for this post */
  ForumPost *pEditNext;  /* This post is edited by pEditNext */
  ForumPost *pEditPrev;  /* This post is an edit of pEditPrev */
  ForumPost *pNext;      /* Next in chronological order */
  ForumPost *pPrev;      /* Previous in chronological order */
  ForumPost *pDisplay;   /* Next in display order */
  int nEdit;             /* Number of edits to this post */
  int nIndent;           /* Number of levels of indentation for this post */
};

/*
** A single instance of the following tracks all entries for a thread.
*/
struct ForumThread {
  ForumPost *pFirst;     /* First post in chronological order */
  ForumPost *pLast;      /* Last post in chronological order */
  ForumPost *pDisplay;   /* Entries in display order */
  ForumPost *pTail;      /* Last on the display list */
  int mxIndent;          /* Maximum indentation level */
};
#endif /* INTERFACE */

/*
** Return true if the forum post with the given rid has been
** subsequently edited.
*/
int forum_rid_has_been_edited(int rid){
  static Stmt q;
  int res;
  db_static_prepare(&q,
     "SELECT 1 FROM forumpost A, forumpost B"
     " WHERE A.fpid=$rid AND B.froot=A.froot AND B.fprev=$rid"
  );
  db_bind_int(&q, "$rid", rid);
  res = db_step(&q)==SQLITE_ROW;
  db_reset(&q);
  return res;
}

/*
** Delete a complete ForumThread and all its entries.
*/
static void forumthread_delete(ForumThread *pThread){
  ForumPost *pPost, *pNext;
  for(pPost=pThread->pFirst; pPost; pPost = pNext){
    pNext = pPost->pNext;
    fossil_free(pPost->zUuid);
    fossil_free(pPost->zDisplayName);
    fossil_free(pPost);
  }
  fossil_free(pThread);
}

/*
** Search a ForumPost list forwards looking for the post with fpid
*/
static ForumPost *forumpost_forward(ForumPost *p, int fpid){
  while( p && p->fpid!=fpid ) p = p->pNext;
  return p;
}

/*
** Search backwards for a ForumPost
*/
static ForumPost *forumpost_backward(ForumPost *p, int fpid){
  while( p && p->fpid!=fpid ) p = p->pPrev;
  return p;
}

/*
** Add a post to the display list
*/
static void forumpost_add_to_display(ForumThread *pThread, ForumPost *p){
  if( pThread->pDisplay==0 ){
    pThread->pDisplay = p;
  }else{
    pThread->pTail->pDisplay = p;
  }
  pThread->pTail = p;
}

/*
** Extend the display list for pThread by adding all entries that
** reference fpid.  The first such post will be no earlier then
** post "p".
*/
static void forumthread_display_order(
  ForumThread *pThread,    /* The complete thread */
  ForumPost *pBase         /* Add replies to this post */
){
  ForumPost *p;
  ForumPost *pPrev = 0;
  ForumPost *pBaseIrt;
  for(p=pBase->pNext; p; p=p->pNext){
    if( !p->pEditPrev && p->pIrt ){
      pBaseIrt = p->pIrt->pEditHead ? p->pIrt->pEditHead : p->pIrt;
      if( pBaseIrt==pBase ){
        if( pPrev ){
          pPrev->nIndent = pBase->nIndent + 1;
          forumpost_add_to_display(pThread, pPrev);
          forumthread_display_order(pThread, pPrev);
        }
        pPrev = p;
      }
    }
  }
  if( pPrev ){
    pPrev->nIndent = pBase->nIndent + 1;
    if( pPrev->nIndent>pThread->mxIndent ) pThread->mxIndent = pPrev->nIndent;
    forumpost_add_to_display(pThread, pPrev);
    forumthread_display_order(pThread, pPrev);
  }
}

/*
** Construct a ForumThread object given the root record id.
*/
static ForumThread *forumthread_create(int froot, int computeHierarchy){
  ForumThread *pThread;
  ForumPost *pPost;
  ForumPost *p;
  Stmt q;
  int sid = 1;
  int firt, fprev;
  pThread = fossil_malloc( sizeof(*pThread) );
  memset(pThread, 0, sizeof(*pThread));
  db_prepare(&q,
     "SELECT fpid, firt, fprev, (SELECT uuid FROM blob WHERE rid=fpid), fmtime"
     "  FROM forumpost"
     " WHERE froot=%d ORDER BY fmtime",
     froot
  );
  while( db_step(&q)==SQLITE_ROW ){
    pPost = fossil_malloc( sizeof(*pPost) );
    memset(pPost, 0, sizeof(*pPost));
    pPost->fpid = db_column_int(&q, 0);
    firt = db_column_int(&q, 1);
    fprev = db_column_int(&q, 2);
    pPost->zUuid = fossil_strdup(db_column_text(&q,3));
    pPost->rDate = db_column_double(&q,4);
    if( !fprev ) pPost->sid = sid++;
    pPost->pPrev = pThread->pLast;
    pPost->pNext = 0;
    if( pThread->pLast==0 ){
      pThread->pFirst = pPost;
    }else{
      pThread->pLast->pNext = pPost;
    }
    pThread->pLast = pPost;

    /* Find the in-reply-to post.  Default to the topic post if the replied-to
    ** post cannot be found. */
    if( firt ){
      pPost->pIrt = pThread->pFirst;
      for(p=pThread->pFirst; p; p=p->pNext){
        if( p->fpid==firt ){
          pPost->pIrt = p;
          break;
        }
      }
    }

    /* Maintain the linked list of post edits. */
    if( fprev ){
      p = forumpost_backward(pPost->pPrev, fprev);
      p->pEditNext = pPost;
      pPost->sid = p->sid;
      pPost->rev = p->rev+1;
      pPost->nEdit = p->nEdit+1;
      pPost->pEditPrev = p;
      pPost->pEditHead = p->pEditHead ? p->pEditHead : p;
      for(; p; p=p->pEditPrev ){
        p->nEdit = pPost->nEdit;
        p->pEditTail = pPost;
      }
    }
  }
  db_finalize(&q);

  if( computeHierarchy ){
    /* Compute the hierarchical display order */
    pPost = pThread->pFirst;
    pPost->nIndent = 1;
    pThread->mxIndent = 1;
    forumpost_add_to_display(pThread, pPost);
    forumthread_display_order(pThread, pPost);
  }

  /* Return the result */
  return pThread;
}

/*
** List all forum threads to standard output.
*/
static void forum_thread_list(void){
  Stmt q;
  db_prepare(&q,
    " SELECT"
    "  datetime(max(fmtime)),"
    "  sum(fprev IS NULL),"
    "  froot"
    " FROM forumpost"
    " GROUP BY froot"
    " ORDER BY 1;"
  );
  fossil_print("    id  cnt    most recent post\n");
  fossil_print("------ ---- -------------------\n");
  while( db_step(&q)==SQLITE_ROW ){
    fossil_print("%6d %4d %s\n",
      db_column_int(&q, 2),
      db_column_int(&q, 1),
      db_column_text(&q, 0)
    );
  }
  db_finalize(&q);
}

/*
** COMMAND: test-forumthread
**
** Usage: %fossil test-forumthread [THREADID]
**
** Display a summary of all messages on a thread THREADID.  If the
** THREADID argument is omitted, then show a list of all threads.
**
** This command is intended for testing an analysis only.
*/
void forumthread_cmd(void){
  int fpid;
  int froot;
  const char *zName;
  ForumThread *pThread;
  ForumPost *p;

  db_find_and_open_repository(0,0);
  verify_all_options();
  if( g.argc==2 ){
    forum_thread_list();
    return;
  }
  if( g.argc!=3 ) usage("THREADID");
  zName = g.argv[2];
  fpid = symbolic_name_to_rid(zName, "f");
  if( fpid<=0 ){
    fpid = db_int(0, "SELECT rid FROM blob WHERE rid=%d", atoi(zName));
  }
  if( fpid<=0 ){
    fossil_fatal("unknown or ambiguous forum id: \"%s\"", zName);
  }
  froot = db_int(0, "SELECT froot FROM forumpost WHERE fpid=%d", fpid);
  if( froot==0 ){
    fossil_fatal("Not a forum post: \"%s\"", zName);
  }
  fossil_print("fpid  = %d\n", fpid);
  fossil_print("froot = %d\n", froot);
  pThread = forumthread_create(froot, 1);
  fossil_print("Chronological:\n");
  fossil_print(
/* 0         1         2         3         4         5         6         7    */
/*  123456789 123456789 123456789 123456789 123456789 123456789 123456789 123 */
  " sid  rev      fpid      pIrt pEditPrev pEditTail hash\n");
  for(p=pThread->pFirst; p; p=p->pNext){
    fossil_print("%4d %4d %9d %9d %9d %9d %8.8s\n", p->sid, p->rev,
       p->fpid, p->pIrt ? p->pIrt->fpid : 0,
       p->pEditPrev ? p->pEditPrev->fpid : 0,
       p->pEditTail ? p->pEditTail->fpid : 0, p->zUuid);
  }
  fossil_print("\nDisplay\n");
  for(p=pThread->pDisplay; p; p=p->pDisplay){
    fossil_print("%*s", (p->nIndent-1)*3, "");
    if( p->pEditTail ){
      fossil_print("%d->%d\n", p->fpid, p->pEditTail->fpid);
    }else{
      fossil_print("%d\n", p->fpid);
    }
  }
  forumthread_delete(pThread);
}

/*
** Render a forum post for display
*/
void forum_render(
  const char *zTitle,         /* The title.  Might be NULL for no title */
  const char *zMimetype,      /* Mimetype of the message */
  const char *zContent,       /* Content of the message */
  const char *zClass,         /* Put in a <div> if not NULL */
  int bScroll                 /* Large message content scrolls if true */
){
  if( zClass ){
    @ <div class='%s(zClass)'>
  }
  if( zTitle ){
    if( zTitle[0] ){
      @ <h1>%h(zTitle)</h1>
    }else{
      @ <h1><i>Deleted</i></h1>
    }
  }
  if( zContent && zContent[0] ){
    Blob x;
    const int isFossilWiki = zMimetype==0
      || fossil_strcmp(zMimetype, "text/x-fossil-wiki")==0;
    if( bScroll ){
      @ <div class='forumPostBody'>
    }else{
      @ <div class='forumPostFullBody'>
    }
    blob_init(&x, 0, 0);
    blob_append(&x, zContent, -1);
    safe_html_context(DOCSRC_FORUM);
    if( isFossilWiki ){
      /* Markdown and plain-text rendering add a wrapper DIV resp. PRE
      ** element around the post, and some CSS relies on its existence
      ** in order to handle expansion/collapse of the post. Fossil
      ** Wiki rendering does not do so, so we must wrap those manually
      ** here. */
      @ <div class='fossilWiki'>
    }
    wiki_render_by_mimetype(&x, zMimetype);
    if( isFossilWiki ){
      @ </div>
    }
    blob_reset(&x);
    @ </div>
  }else{
    @ <i>Deleted</i>
  }
  if( zClass ){
    @ </div>
  }
}

/*
** Compute a display name from a login name.
**
** If the input login is found in the USER table, then check the USER.INFO
** field to see if it has display-name followed by an email address.
** If it does, that becomes the new display name.  If not, let the display
** name just be the login.
**
** Space to hold the returned name is obtained from fossil_strdup() or
** mprintf() and should be freed by the caller.
*/
static char *display_name_from_login(const char *zLogin){
  static Stmt q;
  char *zResult;
  db_static_prepare(&q,
     "SELECT display_name(info) FROM user WHERE login=$login"
  );
  db_bind_text(&q, "$login", zLogin);
  if( db_step(&q)==SQLITE_ROW && db_column_type(&q,0)==SQLITE_TEXT ){
    const char *zDisplay = db_column_text(&q,0);
    if( fossil_strcmp(zDisplay,zLogin)==0 ){
      zResult = fossil_strdup(zLogin);
    }else{
      zResult = mprintf("%s (%s)", zDisplay, zLogin);
    }
  }else{
    zResult = fossil_strdup(zLogin);
  }
  db_reset(&q);
  return zResult;
}

/*
** Compute and return the display name for a ForumPost.  If
** pManifest is not NULL, then it is a Manifest object for the post.
** if pManifest is NULL, this routine has to fetch and parse the
** Manifest object for itself.
**
** Memory to hold the display name is attached to p->zDisplayName
** and will be freed together with the ForumPost object p when it
** is freed.
*/
static char *forum_post_display_name(ForumPost *p, Manifest *pManifest){
  Manifest *pToFree = 0;
  if( p->zDisplayName ) return p->zDisplayName;
  if( pManifest==0 ){
    pManifest = pToFree = manifest_get(p->fpid, CFTYPE_FORUM, 0);
    if( pManifest==0 ) return "(unknown)";
  }
  p->zDisplayName = display_name_from_login(pManifest->zUser);
  if( pToFree ) manifest_destroy(pToFree);
  if( p->zDisplayName==0 ) return "(unknown)";
  return p->zDisplayName;
}


/*
** Display a single post in a forum thread.
*/
static void forum_display_post(
  ForumPost *p,         /* Forum post to display */
  int iIndentScale,     /* Indent scale factor */
  int bRaw,             /* True to omit the border */
  int bUnf,             /* True to leave the post unformatted */
  int bHist,            /* True if showing edit history */
  int bSelect,          /* True if this is the selected post */
  char *zQuery          /* Common query string */
){
  char *zPosterName;    /* Name of user who originally made this post */
  char *zEditorName;    /* Name of user who provided the current edit */
  char *zDate;          /* The time/date string */
  char *zHist;          /* History query string */
  Manifest *pManifest;  /* Manifest comprising the current post */
  int bPrivate;         /* True for posts awaiting moderation */
  int bSameUser;        /* True if author is also the reader */
  int iIndent;          /* Indent level */
  const char *zMimetype;/* Formatting MIME type */

  /* Get the manifest for the post.  Abort if not found (e.g. shunned). */
  pManifest = manifest_get(p->fpid, CFTYPE_FORUM, 0);
  if( !pManifest ) return;

  /* When not in raw mode, create the border around the post. */
  if( !bRaw ){
    /* Open the <div> enclosing the post.  Set the class string to mark the post
    ** as selected and/or obsolete. */
    iIndent = (p->pEditHead ? p->pEditHead->nIndent : p->nIndent)-1;
    @ <div id='forum%d(p->fpid)' class='forumTime\
    @ %s(bSelect ? " forumSel" : "")\
    @ %s(p->pEditTail ? " forumObs" : "")' \
    if( iIndent && iIndentScale ){
      @ style='margin-left:%d(iIndent*iIndentScale)ex;'>
    }else{
      @ >
    }

    /* If this is the first post (or an edit thereof), emit the thread title. */
    if( pManifest->zThreadTitle ){
      @ <h1>%h(pManifest->zThreadTitle)</h1>
    }

    /* Begin emitting the header line.  The forum of the title
    ** varies depending on whether:
    **    *  The post is unedited
    **    *  The post was last edited by the original author
    **    *  The post was last edited by a different person
    */
    if( p->pEditHead ){
      zDate = db_text(0, "SELECT datetime(%.17g,toLocal())", p->pEditHead->rDate);
    }else{
      zPosterName = forum_post_display_name(p, pManifest);
      zEditorName = zPosterName;
    }
    zDate = db_text(0, "SELECT datetime(%.17g,toLocal())", p->rDate);
    if( p->pEditPrev ){
      zPosterName = forum_post_display_name(p->pEditHead, 0);
      zEditorName = forum_post_display_name(p, pManifest);
      zHist = bHist ? "" : "&hist";
      @ <h3 class='forumPostHdr'>(%d(p->sid)\
      @ .%0*d(fossil_num_digits(p->nEdit))(p->rev)) \
      if( fossil_strcmp(zPosterName, zEditorName)==0 ){
        @ By %h(zPosterName) on %h(zDate) edited from \
        @ %z(href("%R/forumpost/%S?%s%s",p->pEditPrev->zUuid,zQuery,zHist))\
        @ %d(p->sid).%0*d(fossil_num_digits(p->nEdit))(p->pEditPrev->rev)</a>
      }else{
        @ Originally by %h(zPosterName) \
        @ with edits by %h(zEditorName) on %h(zDate) from \
        @ %z(href("%R/forumpost/%S?%s%s",p->pEditPrev->zUuid,zQuery,zHist))\
        @ %d(p->sid).%0*d(fossil_num_digits(p->nEdit))(p->pEditPrev->rev)</a>
      }
    }else{
      zPosterName = forum_post_display_name(p, pManifest);
      @ <h3 class='forumPostHdr'>(%d(p->sid)) \
      @ By %h(zPosterName) on %h(zDate)
    }
    fossil_free(zDate);


    /* If debugging is enabled, link to the artifact page. */
    if( g.perm.Debug ){
      @ <span class="debug">\
      @ <a href="%R/artifact/%h(p->zUuid)">(artifact-%d(p->fpid))</a></span>
    }

    /* If this is a reply, refer back to the parent post. */
    if( p->pIrt ){
      @ in reply to %z(href("%R/forumpost/%S?%s",p->pIrt->zUuid,zQuery))\
      @ %d(p->pIrt->sid)\
      if( p->pIrt->nEdit ){
        @ .%0*d(fossil_num_digits(p->pIrt->nEdit))(p->pIrt->rev)\
      }
      @ </a>
    }

    /* If this post was later edited, refer forward to the next edit. */
    if( p->pEditNext ){
      @ updated by %z(href("%R/forumpost/%S?%s",p->pEditNext->zUuid,zQuery))\
      @ %d(p->pEditNext->sid)\
      @ .%0*d(fossil_num_digits(p->nEdit))(p->pEditNext->rev)</a>
    }

    /* Provide a link to select the individual post. */
    if( !bSelect ){
      @ %z(href("%R/forumpost/%S?%s",p->zUuid,zQuery))[link]</a>
    }

    /* Provide a link to the raw source code. */
    if( !bUnf ){
      @ %z(href("%R/forumpost/%S?raw",p->zUuid))[source]</a>
    }
    @ </h3>
  }

  /* Check if this post is approved, also if it's by the current user. */
  bPrivate = content_is_private(p->fpid);
  bSameUser = login_is_individual()
           && fossil_strcmp(pManifest->zUser, g.zLogin)==0;

  /* Render the post if the user is able to see it. */
  if( bPrivate && !g.perm.ModForum && !bSameUser ){
    @ <p><span class="modpending">Awaiting Moderator Approval</span></p>
  }else{
    if( bRaw || bUnf || p->pEditTail ){
      zMimetype = "text/plain";
    }else{
      zMimetype = pManifest->zMimetype;
    }
    forum_render(0, zMimetype, pManifest->zWiki, 0, !bRaw);
  }

  /* When not in raw mode, finish creating the border around the post. */
  if( !bRaw ){
    /* If the user is able to write to the forum and if this post has not been
    ** edited, create a form with various interaction buttons. */
    if( g.perm.WrForum && !p->pEditTail ){
      @ <div><form action="%R/forumedit" method="POST">
      @ <input type="hidden" name="fpid" value="%s(p->zUuid)">
      if( !bPrivate ){
        /* Reply and Edit are only available if the post has been approved. */
        @ <input type="submit" name="reply" value="Reply">
        if( g.perm.Admin || bSameUser ){
          @ <input type="submit" name="edit" value="Edit">
          @ <input type="submit" name="nullout" value="Delete">
        }
      }else if( g.perm.ModForum ){
        /* Allow moderators to approve or reject pending posts.  Also allow
        ** forum supervisors to mark non-special users as trusted and therefore
        ** able to post unmoderated. */
        @ <input type="submit" name="approve" value="Approve">
        @ <input type="submit" name="reject" value="Reject">
        if( g.perm.AdminForum && !login_is_special(pManifest->zUser) ){
          @ <br><label><input type="checkbox" name="trust">
          @ Trust user "%h(pManifest->zUser)" so that future posts by \
          @ "%h(pManifest->zUser)" do not require moderation.
          @ </label>
          @ <input type="hidden" name="trustuser" value="%h(pManifest->zUser)">
        }
      }else if( bSameUser ){
        /* Allow users to delete (reject) their own pending posts. */
        @ <input type="submit" name="reject" value="Delete">
      }
      @ </form></div>
    }
    @ </div>
  }

  /* Clean up. */
  manifest_destroy(pManifest);
}

/*
** Possible display modes for forum_display_thread().
*/
enum {
  FD_RAW,     /* Like FD_SINGLE, but additionally omit the border, force
              ** unformatted mode, and inhibit history mode */
  FD_SINGLE,  /* Render a single post and (optionally) its edit history */
  FD_CHRONO,  /* Render all posts in chronological order */
  FD_HIER,    /* Render all posts in an indented hierarchy */
};

/*
** Display a forum thread.  If mode is FD_RAW or FD_SINGLE, display only a
** single post from the thread and (optionally) its edit history.
*/
static void forum_display_thread(
  int froot,            /* Forum thread root post ID */
  int fpid,             /* Selected forum post ID, or 0 if none selected */
  int mode,             /* Forum display mode, one of the FD_* enumerations */
  int bUnf,             /* True if rendering unformatted */
  int bHist             /* True if showing edit history, ignored for FD_RAW */
){
  ForumThread *pThread; /* Thread structure */
  ForumPost *pSelect;   /* Currently selected post, or NULL if none */
  ForumPost *p;         /* Post iterator pointer */
  char *zQuery;         /* Common query string */
  int iIndentScale = 4; /* Indent scale factor, measured in "ex" units */
  int sid;              /* Comparison serial ID */

  /* In raw mode, force unformatted display and disable history. */
  if( mode == FD_RAW ){
    bUnf = 1;
    bHist = 0;
  }

  /* Thread together the posts and (optionally) compute the hierarchy. */
  pThread = forumthread_create(froot, mode==FD_HIER);

  /* Compute the appropriate indent scaling. */
  if( mode==FD_HIER ){
    iIndentScale = 4;
    while( iIndentScale>1 && iIndentScale*pThread->mxIndent>25 ){
      iIndentScale--;
    }
  }else{
    iIndentScale = 0;
  }

  /* Find the selected post, or (depending on parameters) its latest edit. */
  pSelect = fpid ? forumpost_forward(pThread->pFirst, fpid) : 0;
  if( !bHist && mode!=FD_RAW && pSelect && pSelect->pEditTail ){
    pSelect = pSelect->pEditTail;
  }

  /* When displaying only a single post, abort if no post was selected or the
  ** selected forum post does not exist in the thread.  Otherwise proceed to
  ** display the entire thread without marking any posts as selected. */
  if( !pSelect && (mode==FD_RAW || mode==FD_SINGLE) ){
    return;
  }

  /* Create the common query string to append to nearly all post links. */
  zQuery = mode==FD_RAW ? 0 : mprintf("t=%c%s%s",
      mode==FD_SINGLE ? 's' : mode==FD_CHRONO ? 'c' : 'h',
      bUnf ? "&unf" : "", bHist ? "&hist" : "");

  /* Identify which post to display first.  If history is shown, start with the
  ** original, unedited post.  Otherwise advance to the post's latest edit.  */
  if( mode==FD_RAW || mode==FD_SINGLE ){
    p = pSelect;
    if( bHist && p->pEditHead ) p = p->pEditHead;
  }else{
    p = mode==FD_CHRONO ? pThread->pFirst : pThread->pDisplay;
    if( !bHist && p->pEditTail ) p = p->pEditTail;
  }

  /* Display the appropriate subset of posts in sequence. */
  while( p ){
    /* Display the post. */
    forum_display_post(p, iIndentScale, mode==FD_RAW,
        bUnf, bHist, p==pSelect, zQuery);

    /* Advance to the next post in the thread. */
    if( mode==FD_CHRONO ){
      /* Chronological mode: display posts (optionally including edits) in their
      ** original commit order. */
      if( bHist ){
        p = p->pNext;
      }else{
        sid = p->sid;
        if( p->pEditHead ) p = p->pEditHead;
        do p = p->pNext; while( p && p->sid<=sid );
        if( p && p->pEditTail ) p = p->pEditTail;
      }
    }else if( bHist && p->pEditNext ){
      /* Hierarchical and single mode: display each post's edits in sequence. */
      p = p->pEditNext;
    }else if( mode==FD_HIER ){
      /* Hierarchical mode: after displaying with each post (optionally
      ** including edits), go to the next post in computed display order. */
      p = p->pEditHead ? p->pEditHead->pDisplay : p->pDisplay;
      if( !bHist && p && p->pEditTail ) p = p->pEditTail;
    }else{
      /* Single and raw mode: terminate after displaying the selected post and
      ** (optionally) its edits. */
      break;
    }
  }

  /* Undocumented "threadtable" query parameter causes thread table to be
  ** displayed for debugging purposes. */
  if( PB("threadtable") ){
    @ <hr>
    @ <table border="1" cellpadding="3" cellspacing="0">
    @ <tr><th>sid<th>rev<th>fpid<th>pIrt<th>pEditHead<th>pEditTail\
    @ <th>pEditNext<th>pEditPrev<th>pDisplay<th>hash
    for(p=pThread->pFirst; p; p=p->pNext){
      @ <tr><td>%d(p->sid)<td>%d(p->rev)<td>%d(p->fpid)\
      @ <td>%d(p->pIrt ? p->pIrt->fpid : 0)\
      @ <td>%d(p->pEditHead ? p->pEditHead->fpid : 0)\
      @ <td>%d(p->pEditTail ? p->pEditTail->fpid : 0)\
      @ <td>%d(p->pEditNext ? p->pEditNext->fpid : 0)\
      @ <td>%d(p->pEditPrev ? p->pEditPrev->fpid : 0)\
      @ <td>%d(p->pDisplay ? p->pDisplay->fpid : 0)\
      @ <td>%S(p->zUuid)</tr>
    }
    @ </table>
  }

  /* Clean up. */
  forumthread_delete(pThread);
  fossil_free(zQuery);
}

/*
** Emit Forum Javascript which applies (or optionally can apply)
** to all forum-related pages. It does not include page-specific
** code (e.g. "forum.js").
*/
static void forum_emit_js(void){
  builtin_fossil_js_bundle_or("copybutton", "pikchr", NULL);
  builtin_request_js("fossil.page.forumpost.js");
}

/*
** WEBPAGE: forumpost
**
** Show a single forum posting. The posting is shown in context with
** its entire thread.  The selected posting is enclosed within
** <div class='forumSel'>...</div>.  Javascript is used to move the
** selected posting into view after the page loads.
**
** Query parameters:
**
**   name=X        REQUIRED.  The hash of the post to display.
**   t=a           Automatic display mode, i.e. hierarchical for
**                 desktop and chronological for mobile.  This is the
**                 default if the "t" query parameter is omitted.
**   t=c           Show posts in the order they were written.
**   t=h           Show posts using hierarchical indenting.
**   t=s           Show only the post specified by "name=X".
**   t=r           Alias for "t=c&unf&hist".
**   t=y           Alias for "t=s&unf&hist".
**   raw           Alias for "t=s&unf".  Additionally, omit the border
**                 around the post, and ignore "t" and "hist".
**   unf           Show the original, unformatted source text.
**   hist          Show edit history in addition to current posts.
*/
void forumpost_page(void){
  forumthread_page();
}

/*
** WEBPAGE: forumthread
**
** Show all forum messages associated with a particular message thread.
** The result is basically the same as /forumpost except that none of
** the postings in the thread are selected.
**
** Query parameters:
**
**   name=X        REQUIRED.  The hash of any post of the thread.
**   t=a           Automatic display mode, i.e. hierarchical for
**                 desktop and chronological for mobile.  This is the
**                 default if the "t" query parameter is omitted.
**   t=c           Show posts in the order they were written.
**   t=h           Show posts using hierarchical indenting.
**   unf           Show the original, unformatted source text.
**   hist          Show edit history in addition to current posts.
*/
void forumthread_page(void){
  int fpid;
  int froot;
  char *zThreadTitle;
  const char *zName = P("name");
  const char *zMode = PD("t","a");
  int bRaw = PB("raw");
  int bUnf = PB("unf");
  int bHist = PB("hist");
  int mode = 0;
  login_check_credentials();
  if( !g.perm.RdForum ){
    login_needed(g.anon.RdForum);
    return;
  }
  if( zName==0 ){
    webpage_error("Missing \"name=\" query parameter");
  }
  fpid = symbolic_name_to_rid(zName, "f");
  if( fpid<=0 ){
    if( fpid==0 ){
      webpage_notfound_error("Unknown forum id: \"%s\"", zName);
    }else{
      ambiguous_page();
    }
    return;
  }
  froot = db_int(0, "SELECT froot FROM forumpost WHERE fpid=%d", fpid);
  if( froot==0 ){
    webpage_notfound_error("Not a forum post: \"%s\"", zName);
  }
  if( fossil_strcmp(g.zPath,"forumthread")==0 ) fpid = 0;

  /* Decode the mode parameters. */
  if( bRaw ){
    mode = FD_RAW;
    bUnf = 1;
    bHist = 0;
    cgi_replace_query_parameter("unf", "on");
    cgi_delete_query_parameter("hist");
    cgi_delete_query_parameter("raw");
  }else{
    switch( *zMode ){
      case 'a': mode = cgi_from_mobile() ? FD_CHRONO : FD_HIER; break;
      case 'c': mode = FD_CHRONO; break;
      case 'h': mode = FD_HIER; break;
      case 's': mode = FD_SINGLE; break;
      case 'r': mode = FD_CHRONO; break;
      case 'y': mode = FD_SINGLE; break;
      default: webpage_error("Invalid thread mode: \"%s\"", zMode);
    }
    if( *zMode=='r' || *zMode=='y') {
      bUnf = 1;
      bHist = 1;
      cgi_replace_query_parameter("t", mode==FD_CHRONO ? "c" : "s");
      cgi_replace_query_parameter("unf", "on");
      cgi_replace_query_parameter("hist", "on");
    }
  }

  /* Define the page header. */
  zThreadTitle = db_text("",
    "SELECT"
    " substr(event.comment,instr(event.comment,':')+2)"
    " FROM forumpost, event"
    " WHERE event.objid=forumpost.fpid"
    "   AND forumpost.fpid=%d;",
    fpid
  );
  style_set_current_feature("forum");
  style_header("%s%s", zThreadTitle, *zThreadTitle ? "" : "Forum");
  fossil_free(zThreadTitle);
  if( mode!=FD_CHRONO ){
    style_submenu_element("Chronological", "%R/%s/%s?t=c%s%s", g.zPath, zName,
        bUnf ? "&unf" : "", bHist ? "&hist" : "");
  }
  if( mode!=FD_HIER ){
    style_submenu_element("Hierarchical", "%R/%s/%s?t=h%s%s", g.zPath, zName,
        bUnf ? "&unf" : "", bHist ? "&hist" : "");
  }
  style_submenu_checkbox("unf", "Unformatted", 0, 0);
  style_submenu_checkbox("hist", "History", 0, 0);

  /* Display the thread. */
  forum_display_thread(froot, fpid, mode, bUnf, bHist);

  /* Emit Forum Javascript. */
  builtin_request_js("forum.js");
  forum_emit_js();

  /* Emit the page style. */
  style_finish_page();
}

/*
** Return true if a forum post should be moderated.
*/
static int forum_need_moderation(void){
  if( P("domod") ) return 1;
  if( g.perm.WrTForum ) return 0;
  if( g.perm.ModForum ) return 0;
  return 1;
}

/*
** Return true if the string is white-space only.
*/
static int whitespace_only(const char *z){
  if( z==0 ) return 1;
  while( z[0] && fossil_isspace(z[0]) ){ z++; }
  return z[0]==0;
}

/*
** Add a new Forum Post artifact to the repository.
**
** Return true if a redirect occurs.
*/
static int forum_post(
  const char *zTitle,          /* Title.  NULL for replies */
  int iInReplyTo,              /* Post replying to.  0 for new threads */
  int iEdit,                   /* Post being edited, or zero for a new post */
  const char *zUser,           /* Username.  NULL means use login name */
  const char *zMimetype,       /* Mimetype of content. */
  const char *zContent         /* Content */
){
  char *zDate;
  char *zI;
  char *zG;
  int iBasis;
  Blob x, cksum, formatCheck, errMsg;
  Manifest *pPost;
  int nContent = zContent ? (int)strlen(zContent) : 0;

  schema_forum();
  if( iEdit==0 && whitespace_only(zContent) ){
    return 0;
  }
  if( iInReplyTo==0 && iEdit>0 ){
    iBasis = iEdit;
    iInReplyTo = db_int(0, "SELECT firt FROM forumpost WHERE fpid=%d", iEdit);
  }else{
    iBasis = iInReplyTo;
  }
  webpage_assert( (zTitle==0)+(iInReplyTo==0)==1 );
  blob_init(&x, 0, 0);
  zDate = date_in_standard_format("now");
  blob_appendf(&x, "D %s\n", zDate);
  fossil_free(zDate);
  zG = db_text(0,
     "SELECT uuid FROM blob, forumpost"
     " WHERE blob.rid==forumpost.froot"
     "   AND forumpost.fpid=%d", iBasis);
  if( zG ){
    blob_appendf(&x, "G %s\n", zG);
    fossil_free(zG);
  }
  if( zTitle ){
    blob_appendf(&x, "H %F\n", zTitle);
  }
  zI = db_text(0, "SELECT uuid FROM blob WHERE rid=%d", iInReplyTo);
  if( zI ){
    blob_appendf(&x, "I %s\n", zI);
    fossil_free(zI);
  }
  if( fossil_strcmp(zMimetype,"text/x-fossil-wiki")!=0 ){
    blob_appendf(&x, "N %s\n", zMimetype);
  }
  if( iEdit>0 ){
    char *zP = db_text(0, "SELECT uuid FROM blob WHERE rid=%d", iEdit);
    if( zP==0 ) webpage_error("missing edit artifact %d", iEdit);
    blob_appendf(&x, "P %s\n", zP);
    fossil_free(zP);
  }
  if( zUser==0 ){
    if( login_is_nobody() ){
      zUser = "anonymous";
    }else{
      zUser = login_name();
    }
  }
  blob_appendf(&x, "U %F\n", zUser);
  blob_appendf(&x, "W %d\n%s\n", nContent, zContent);
  md5sum_blob(&x, &cksum);
  blob_appendf(&x, "Z %b\n", &cksum);
  blob_reset(&cksum);

  /* Verify that the artifact we are creating is well-formed */
  blob_init(&formatCheck, 0, 0);
  blob_init(&errMsg, 0, 0);
  blob_copy(&formatCheck, &x);
  pPost = manifest_parse(&formatCheck, 0, &errMsg);
  if( pPost==0 ){
    webpage_error("malformed forum post artifact - %s", blob_str(&errMsg));
  }
  webpage_assert( pPost->type==CFTYPE_FORUM );
  manifest_destroy(pPost);

  if( P("dryrun") ){
    @ <div class='debug'>
    @ This is the artifact that would have been generated:
    @ <pre>%h(blob_str(&x))</pre>
    @ </div>
    blob_reset(&x);
    return 0;
  }else{
    int nrid = wiki_put(&x, iEdit>0 ? iEdit : 0,
                        forum_need_moderation());
    blob_reset(&x);
    cgi_redirectf("%R/forumpost/%S", rid_to_uuid(nrid));
    return 1;
  }
}

/*
** Paint the form elements for entering a Forum post
*/
static void forum_post_widget(
  const char *zTitle,
  const char *zMimetype,
  const char *zContent
){
  if( zTitle ){
    @ Title: <input type="input" name="title" value="%h(zTitle)" size="50"
    @ maxlength="125"><br>
  }
  @ %z(href("%R/markup_help"))Markup style</a>:
  mimetype_option_menu(zMimetype);
  @ <br><textarea aria-label="Content:" name="content" class="wikiedit" \
  @ cols="80" rows="25" wrap="virtual">%h(zContent)</textarea><br>
}

/*
** WEBPAGE: forumnew
** WEBPAGE: forumedit
**
** Start a new thread on the forum or reply to an existing thread.
** But first prompt to see if the user would like to log in.
*/
void forum_page_init(void){
  int isEdit;
  char *zGoto;
  login_check_credentials();
  if( !g.perm.WrForum ){
    login_needed(g.anon.WrForum);
    return;
  }
  if( sqlite3_strglob("*edit*", g.zPath)==0 ){
    zGoto = mprintf("%R/forume2?fpid=%S",PD("fpid",""));
    isEdit = 1;
  }else{
    zGoto = mprintf("%R/forume1");
    isEdit = 0;
  }
  if( login_is_individual() ){
    if( isEdit ){
      forumedit_page();
    }else{
      forumnew_page();
    }
    return;
  }
  style_set_current_feature("forum");
  style_header("%h As Anonymous?", isEdit ? "Reply" : "Post");
  @ <p>You are not logged in.
  @ <p><table border="0" cellpadding="10">
  @ <tr><td>
  @ <form action="%s(zGoto)" method="POST">
  @ <input type="submit" value="Remain Anonymous">
  @ </form>
  @ <td>Post to the forum anonymously
  if( login_self_register_available(0) ){
    @ <tr><td>
    @ <form action="%R/register" method="POST">
    @ <input type="hidden" name="g" value="%s(zGoto)">
    @ <input type="submit" value="Create An Account">
    @ </form>
    @ <td>Create a new account and post using that new account
  }
  @ <tr><td>
  @ <form action="%R/login" method="POST">
  @ <input type="hidden" name="g" value="%s(zGoto)">
  @ <input type="hidden" name="noanon" value="1">
  @ <input type="submit" value="Login">
  @ </form>
  @ <td>Log into an existing account
  @ </table>
  forum_emit_js();
  style_finish_page();
  fossil_free(zGoto);
}

/*
** Write the "From: USER" line on the webpage.
*/
static void forum_from_line(void){
  if( login_is_nobody() ){
    @ From: anonymous<br>
  }else{
    @ From: %h(login_name())<br>
  }
}

/*
** WEBPAGE: forume1
**
** Start a new forum thread.
*/
void forumnew_page(void){
  const char *zTitle = PDT("title","");
  const char *zMimetype = PD("mimetype",DEFAULT_FORUM_MIMETYPE);
  const char *zContent = PDT("content","");
  login_check_credentials();
  if( !g.perm.WrForum ){
    login_needed(g.anon.WrForum);
    return;
  }
  if( P("submit") && cgi_csrf_safe(1) ){
    if( forum_post(zTitle, 0, 0, 0, zMimetype, zContent) ) return;
  }
  if( P("preview") && !whitespace_only(zContent) ){
    @ <h1>Preview:</h1>
    forum_render(zTitle, zMimetype, zContent, "forumEdit", 1);
  }
  style_set_current_feature("forum");
  style_header("New Forum Thread");
  @ <form action="%R/forume1" method="POST">
  @ <h1>New Thread:</h1>
  forum_from_line();
  forum_post_widget(zTitle, zMimetype, zContent);
  @ <input type="submit" name="preview" value="Preview">
  if( P("preview") && !whitespace_only(zContent) ){
    @ <input type="submit" name="submit" value="Submit">
  }else{
    @ <input type="submit" name="submit" value="Submit" disabled>
  }
  if( g.perm.Debug ){
    /* Give extra control over the post to users with the special
     * Debug capability, which includes Admin and Setup users */
    @ <div class="debug">
    @ <label><input type="checkbox" name="dryrun" %s(PCK("dryrun"))> \
    @ Dry run</label>
    @ <br><label><input type="checkbox" name="domod" %s(PCK("domod"))> \
    @ Require moderator approval</label>
    @ <br><label><input type="checkbox" name="showqp" %s(PCK("showqp"))> \
    @ Show query parameters</label>
    @ </div>
  }
  @ </form>
  forum_emit_js();
  style_finish_page();
}

/*
** WEBPAGE: forume2
**
** Edit an existing forum message.
** Query parameters:
**
**   fpid=X        Hash of the post to be edited.  REQUIRED
*/
void forumedit_page(void){
  int fpid;
  int froot;
  Manifest *pPost = 0;
  Manifest *pRootPost = 0;
  const char *zMimetype = 0;
  const char *zContent = 0;
  const char *zTitle = 0;
  char *zDate = 0;
  int isCsrfSafe;
  int isDelete = 0;

  login_check_credentials();
  if( !g.perm.WrForum ){
    login_needed(g.anon.WrForum);
    return;
  }
  fpid = symbolic_name_to_rid(PD("fpid",""), "f");
  if( fpid<=0 || (pPost = manifest_get(fpid, CFTYPE_FORUM, 0))==0 ){
    webpage_error("Missing or invalid fpid query parameter");
  }
  froot = db_int(0, "SELECT froot FROM forumpost WHERE fpid=%d", fpid);
  if( froot==0 || (pRootPost = manifest_get(froot, CFTYPE_FORUM, 0))==0 ){
    webpage_error("fpid does not appear to be a forum post: \"%d\"", fpid);
  }
  if( P("cancel") ){
    cgi_redirectf("%R/forumpost/%S",P("fpid"));
    return;
  }
  isCsrfSafe = cgi_csrf_safe(1);
  if( g.perm.ModForum && isCsrfSafe ){
    if( P("approve") ){
      const char *zUserToTrust;
      moderation_approve('f', fpid);
      if( g.perm.AdminForum
       && PB("trust")
       && (zUserToTrust = P("trustuser"))!=0
      ){
        db_unprotect(PROTECT_USER);
        db_multi_exec("UPDATE user SET cap=cap||'4' "
                      "WHERE login=%Q AND cap NOT GLOB '*4*'",
                      zUserToTrust);
        db_protect_pop();
      }
      cgi_redirectf("%R/forumpost/%S",P("fpid"));
      return;
    }
    if( P("reject") ){
      char *zParent =
        db_text(0,
          "SELECT uuid FROM forumpost, blob"
          " WHERE forumpost.fpid=%d AND blob.rid=forumpost.firt",
          fpid
        );
      moderation_disapprove(fpid);
      if( zParent ){
        cgi_redirectf("%R/forumpost/%S",zParent);
      }else{
        cgi_redirectf("%R/forum");
      }
      return;
    }
  }
  style_set_current_feature("forum");
  isDelete = P("nullout")!=0;
  if( P("submit")
   && isCsrfSafe
   && (zContent = PDT("content",""))!=0
   && (!whitespace_only(zContent) || isDelete)
  ){
    int done = 1;
    const char *zMimetype = PD("mimetype",DEFAULT_FORUM_MIMETYPE);
    if( P("reply") ){
      done = forum_post(0, fpid, 0, 0, zMimetype, zContent);
    }else if( P("edit") || isDelete ){
      done = forum_post(P("title"), 0, fpid, 0, zMimetype, zContent);
    }else{
      webpage_error("Missing 'reply' query parameter");
    }
    if( done ) return;
  }
  if( isDelete ){
    zMimetype = "text/x-fossil-wiki";
    zContent = "";
    if( pPost->zThreadTitle ) zTitle = "";
    style_header("Delete %s", zTitle ? "Post" : "Reply");
    @ <h1>Original Post:</h1>
    forum_render(pPost->zThreadTitle, pPost->zMimetype, pPost->zWiki,
                 "forumEdit", 1);
    @ <h1>Change Into:</h1>
    forum_render(zTitle, zMimetype, zContent,"forumEdit", 1);
    @ <form action="%R/forume2" method="POST">
    @ <input type="hidden" name="fpid" value="%h(P("fpid"))">
    @ <input type="hidden" name="nullout" value="1">
    @ <input type="hidden" name="mimetype" value="%h(zMimetype)">
    @ <input type="hidden" name="content" value="%h(zContent)">
    if( zTitle ){
      @ <input aria-label="Title" type="hidden" name="title" value="%h(zTitle)">
    }
  }else if( P("edit") ){
    /* Provide an edit to the fpid post */
    zMimetype = P("mimetype");
    zContent = PT("content");
    zTitle = P("title");
    if( zContent==0 ) zContent = fossil_strdup(pPost->zWiki);
    if( zMimetype==0 ) zMimetype = fossil_strdup(pPost->zMimetype);
    if( zTitle==0 && pPost->zThreadTitle!=0 ){
      zTitle = fossil_strdup(pPost->zThreadTitle);
    }
    style_header("Edit %s", zTitle ? "Post" : "Reply");
    @ <h2>Original Post:</h2>
    forum_render(pPost->zThreadTitle, pPost->zMimetype, pPost->zWiki,
                 "forumEdit", 1);
    if( P("preview") ){
      @ <h2>Preview of Edited Post:</h2>
      forum_render(zTitle, zMimetype, zContent,"forumEdit", 1);
    }
    @ <h2>Revised Message:</h2>
    @ <form action="%R/forume2" method="POST">
    @ <input type="hidden" name="fpid" value="%h(P("fpid"))">
    @ <input type="hidden" name="edit" value="1">
    forum_from_line();
    forum_post_widget(zTitle, zMimetype, zContent);
  }else{
    /* Reply */
    char *zDisplayName;
    zMimetype = PD("mimetype",DEFAULT_FORUM_MIMETYPE);
    zContent = PDT("content","");
    style_header("Reply");
    if( pRootPost->zThreadTitle ){
      @ <h1>Thread: %h(pRootPost->zThreadTitle)</h1>
    }
    @ <h2>Replying To:</h2>
    zDate = db_text(0, "SELECT datetime(%.17g,toLocal())", pPost->rDate);
    zDisplayName = display_name_from_login(pPost->zUser);
    @ <h3 class='forumPostHdr'>By %h(zDisplayName) on %h(zDate)</h3>
    fossil_free(zDisplayName);
    fossil_free(zDate);
    forum_render(0, pPost->zMimetype, pPost->zWiki, "forumEdit", 1);
    if( P("preview") && !whitespace_only(zContent) ){
      @ <h2>Preview:</h2>
      forum_render(0, zMimetype,zContent, "forumEdit", 1);
    }
    @ <h2>Enter Reply:</h2>
    @ <form action="%R/forume2" method="POST">
    @ <input type="hidden" name="fpid" value="%h(P("fpid"))">
    @ <input type="hidden" name="reply" value="1">
    forum_from_line();
    forum_post_widget(0, zMimetype, zContent);
  }
  if( !isDelete ){
    @ <input type="submit" name="preview" value="Preview">
  }
  @ <input type="submit" name="cancel" value="Cancel">
  if( (P("preview") && !whitespace_only(zContent)) || isDelete ){
    @ <input type="submit" name="submit" value="Submit">
  }
  if( g.perm.Debug ){
    /* For the test-forumnew page add these extra debugging controls */
    @ <div class="debug">
    @ <label><input type="checkbox" name="dryrun" %s(PCK("dryrun"))> \
    @ Dry run</label>
    @ <br><label><input type="checkbox" name="domod" %s(PCK("domod"))> \
    @ Require moderator approval</label>
    @ <br><label><input type="checkbox" name="showqp" %s(PCK("showqp"))> \
    @ Show query parameters</label>
    @ </div>
  }
  @ </form>
  forum_emit_js();
  style_finish_page();
}

/*
** WEBPAGE: forummain
** WEBPAGE: forum
**
** The main page for the forum feature.  Show a list of recent forum
** threads.  Also show a search box at the top if search is enabled,
** and a button for creating a new thread, if enabled.
**
** Query parameters:
**
**    n=N             The number of threads to show on each page
**    x=X             Skip the first X threads
*/
void forum_main_page(void){
  Stmt q;
  int iLimit, iOfst, iCnt;
  int srchFlags;
  login_check_credentials();
  srchFlags = search_restrict(SRCH_FORUM);
  if( !g.perm.RdForum ){
    login_needed(g.anon.RdForum);
    return;
  }
  style_set_current_feature("forum");
  style_header("Forum");
  if( g.perm.WrForum ){
    style_submenu_element("New Thread","%R/forumnew");
  }else{
    /* Can't combine this with previous case using the ternary operator
     * because that causes an error yelling about "non-constant format"
     * with some compilers.  I can't see it, since both expressions have
     * the same format, but I'm no C spec lawyer. */
    style_submenu_element("New Thread","%R/login");
  }
  if( g.perm.ModForum && moderation_needed() ){
    style_submenu_element("Moderation Requests", "%R/modreq");
  }
  if( (srchFlags & SRCH_FORUM)!=0 ){
    if( search_screen(SRCH_FORUM, 0) ){
      style_submenu_element("Recent Threads","%R/forum");
      style_finish_page();
      return;
    }
  }
  iLimit = atoi(PD("n","25"));
  iOfst = atoi(PD("x","0"));
  iCnt = 0;
  if( db_table_exists("repository","forumpost") ){
    db_prepare(&q,
      "WITH thread(age,duration,cnt,root,last) AS ("
      "  SELECT"
      "    julianday('now') - max(fmtime),"
      "    max(fmtime) - min(fmtime),"
      "    sum(fprev IS NULL),"
      "    froot,"
      "    (SELECT fpid FROM forumpost AS y"
      "      WHERE y.froot=x.froot %s"
      "      ORDER BY y.fmtime DESC LIMIT 1)"
      "  FROM forumpost AS x"
      "  WHERE %s"
      "  GROUP BY froot"
      "  ORDER BY 1 LIMIT %d OFFSET %d"
      ")"
      "SELECT"
      "  thread.age,"                                         /* 0 */
      "  thread.duration,"                                    /* 1 */
      "  thread.cnt,"                                         /* 2 */
      "  blob.uuid,"                                          /* 3 */
      "  substr(event.comment,instr(event.comment,':')+1),"   /* 4 */
      "  thread.last"                                         /* 5 */
      " FROM thread, blob, event"
      " WHERE blob.rid=thread.last"
      "  AND event.objid=thread.last"
      " ORDER BY 1;",
      g.perm.ModForum ? "" : "AND y.fpid NOT IN private" /*safe-for-%s*/,
      g.perm.ModForum ? "true" : "fpid NOT IN private" /*safe-for-%s*/,
      iLimit+1, iOfst
    );
    while( db_step(&q)==SQLITE_ROW ){
      char *zAge = human_readable_age(db_column_double(&q,0));
      int nMsg = db_column_int(&q, 2);
      const char *zUuid = db_column_text(&q, 3);
      const char *zTitle = db_column_text(&q, 4);
      if( iCnt==0 ){
        if( iOfst>0 ){
          @ <h1>Threads at least %s(zAge) old</h1>
        }else{
          @ <h1>Most recent threads</h1>
        }
        @ <div class='forumPosts fileage'><table width="100%%">
        if( iOfst>0 ){
          if( iOfst>iLimit ){
            @ <tr><td colspan="3">\
            @ %z(href("%R/forum?x=%d&n=%d",iOfst-iLimit,iLimit))\
            @ &uarr; Newer...</a></td></tr>
          }else{
            @ <tr><td colspan="3">%z(href("%R/forum?n=%d",iLimit))\
            @ &uarr; Newer...</a></td></tr>
          }
        }
      }
      iCnt++;
      if( iCnt>iLimit ){
        @ <tr><td colspan="3">\
        @ %z(href("%R/forum?x=%d&n=%d",iOfst+iLimit,iLimit))\
        @ &darr; Older...</a></td></tr>
        fossil_free(zAge);
        break;
      }
      @ <tr><td>%h(zAge) ago</td>
      @ <td>%z(href("%R/forumpost/%S",zUuid))%h(zTitle)</a></td>
      @ <td>\
      if( g.perm.ModForum && moderation_pending(db_column_int(&q,5)) ){
        @ <span class="modpending">\
        @ Awaiting Moderator Approval</span><br>
      }
      if( nMsg<2 ){
        @ no replies</td>
      }else{
        char *zDuration = human_readable_age(db_column_double(&q,1));
        @ %d(nMsg) posts spanning %h(zDuration)</td>
        fossil_free(zDuration);
      }
      @ </tr>
      fossil_free(zAge);
    }
    db_finalize(&q);
  }
  if( iCnt>0 ){
    @ </table></div>
  }else{
    @ <h1>No forum posts found</h1>
  }
  style_finish_page();
}
