/*
** Copyright (c) 2016 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 map command names (ex: "help", "commit",
** "diff") or webpage names (ex: "/timeline", "/search") into the functions
** that implement those commands and web pages and their associated help
** text.
*/
#include "config.h"
#include <assert.h>
#include "dispatch.h"

#if INTERFACE
/*
** An instance of this object defines everything we need to know about an
** individual command, webpage, or setting.
*/
struct CmdOrPage {
  const char *zName;       /* Name.  Webpages start with "/". Commands do not */
  void (*xFunc)(void);     /* Implementation function, or NULL for settings */
  const char *zHelp;       /* Raw help text */
  unsigned int eCmdFlags;  /* Flags */
};

/***************************************************************************
** These macros must match similar macros in mkindex.c
** Allowed values for CmdOrPage.eCmdFlags.
*/
#define CMDFLAG_1ST_TIER    0x0001      /* Most important commands */
#define CMDFLAG_2ND_TIER    0x0002      /* Obscure and seldom used commands */
#define CMDFLAG_TEST        0x0004      /* Commands for testing only */
#define CMDFLAG_WEBPAGE     0x0008      /* Web pages */
#define CMDFLAG_COMMAND     0x0010      /* A command */
#define CMDFLAG_SETTING     0x0020      /* A setting */
#define CMDFLAG_VERSIONABLE 0x0040      /* A versionable setting */
#define CMDFLAG_BLOCKTEXT   0x0080      /* Multi-line text setting */
#define CMDFLAG_BOOLEAN     0x0100      /* A boolean setting */
#define CMDFLAG_RAWCONTENT  0x0200      /* Do not interpret POST content */
/**************************************************************************/

/* Values for the 2nd parameter to dispatch_name_search() */
#define CMDFLAG_ANY         0x0038      /* Match anything */
#define CMDFLAG_PREFIX      0x0200      /* Prefix match is ok */

#endif /* INTERFACE */

/*
** The page_index.h file contains the definition for aCommand[] - an array
** of CmdOrPage objects that defines all available commands and webpages
** known to Fossil.
**
** The entries in aCommand[] are in sorted order by name.  Since webpage names
** always begin with "/", all webpage names occur first.  The page_index.h file
** also sets the FOSSIL_FIRST_CMD macro to be the *approximate* index
** in aCommand[] of the first command entry.  FOSSIL_FIRST_CMD might be
** slightly too low, and so the range FOSSIL_FIRST_CMD...MX_COMMAND might
** contain a few webpage entries at the beginning.
**
** The page_index.h file is generated by the mkindex program which scans all
** source code files looking for header comments on the functions that
** implement command and webpages.
*/
#include "page_index.h"
#define MX_COMMAND count(aCommand)

/*
** Given a command, webpage, or setting name in zName, find the corresponding
** CmdOrPage object and return a pointer to that object in *ppCmd.
**
** The eType field is CMDFLAG_COMMAND to look up commands, CMDFLAG_WEBPAGE to
** look up webpages, CMDFLAG_SETTING to look up settings, or CMDFLAG_ANY to look
** for any.  If the CMDFLAG_PREFIX bit is set, then a prefix match is allowed.
**
** Return values:
**    0:     Success.  *ppCmd is set to the appropriate CmdOrPage
**    1:     Not found.
**    2:     Ambiguous.  Two or more entries match.
*/
int dispatch_name_search(
  const char *zName,           /* Look for this name */
  unsigned eType,              /* CMDFLAGS_* bits */
  const CmdOrPage **ppCmd      /* Write the matching CmdOrPage object here */
){
  int upr, lwr, mid;
  int nName = strlen(zName);
  lwr = 0;
  upr = MX_COMMAND - 1;
  while( lwr<=upr ){
    int c;
    mid = (upr+lwr)/2;
    c = strcmp(zName, aCommand[mid].zName);
    if( c==0 ){
      if( (aCommand[mid].eCmdFlags & eType)==0 ) return 1;
      *ppCmd = &aCommand[mid];
      return 0;  /* An exact match */
    }else if( c<0 ){
      upr = mid - 1;
    }else{
      lwr = mid + 1;
    }
  }
  if( (eType & CMDFLAG_PREFIX)!=0
   && lwr<MX_COMMAND
   && strncmp(zName, aCommand[lwr].zName, nName)==0
  ){
    /* An inexact prefix match was found.  Scan the name table to try to find
     * exactly one entry with this prefix and the requested type. */
    for( mid=-1; lwr<MX_COMMAND
              && strncmp(zName, aCommand[lwr].zName, nName)==0; ++lwr ){
      if( aCommand[lwr].eCmdFlags & eType ){
        if( mid<0 ){
          mid = lwr;  /* Potential ambiguous prefix */
        }else{
          return 2;  /* Confirmed ambiguous prefix */
        }
      }
    }
    if( mid>=0 ){
      *ppCmd = &aCommand[mid];
      return 0;  /* Prefix match */
    }
  }
  return 1;  /* Not found */
}

/*
** zName is the name of a webpage (eType==CMDFLAGS_WEBPAGE) that does not
** exist in the dispatch table.  Check to see if this webpage name exists
** as an alias in the CONFIG table of the repository.  If it is, then make
** appropriate changes to the CGI environment and set *ppCmd to point to the
** aliased command.
**
** Return 0 if the command is successfully aliased.  Return 1 if there
** is not alias for zName.  Any kind of error in the alias value causes a
** error to be thrown.
**
** Alias entries in the CONFIG table have a "name" value of "walias:NAME"
** where NAME is the input page name.  The value is a string of the form
** "NEWNAME?QUERYPARAMS".  The ?QUERYPARAMS is optional.  If present (and it
** usually is), then all query parameters are added to the CGI environment.
** Except, query parameters of the form "X!" cause any CGI X variable to be
** removed.
*/
int dispatch_alias(const char *zName, const CmdOrPage **ppCmd){
  char *z;
  char *zQ;
  int i;

  z = db_text(0, "SELECT value FROM config WHERE name='walias:%q'",zName);
  if( z==0 ) return 1;
  for(i=0; z[i] && z[i]!='?'; i++){}
  if( z[i]=='?' ){
    z[i] = 0;
    zQ = &z[i+1];
  }else{
    zQ = &z[i];
  }
  if( dispatch_name_search(z, CMDFLAG_WEBPAGE, ppCmd) ){
    fossil_fatal("\"%s\" aliased to \"%s\" but \"%s\" does not exist",
                 zName, z, z);
  }
  z = zQ;
  while( *z ){
    char *zName = z;
    char *zValue = 0;
    while( *z && *z!='=' && *z!='&' && *z!='!' ){ z++; }
    if( *z=='=' ){
      *z = 0;
      z++;
      zValue = z;
      while( *z && *z!='&' ){ z++; }
      if( *z ){
        *z = 0;
        z++;
      }
      dehttpize(zValue);
    }else if( *z=='!' ){
      *(z++) = 0;
      cgi_delete_query_parameter(zName);
      zName = "";
    }else{
      if( *z ){ *z++ = 0; }
      zValue = "";
    }
    if( fossil_islower(zName[0]) ){
      cgi_replace_query_parameter(zName, zValue);
    }else if( fossil_isupper(zName[0]) ){
      cgi_replace_query_parameter_tolower(zName, zValue);
    }
  }
  return 0;
}

/*
** Fill Blob with a space-separated list of all command names that
** match the prefix zPrefix.
*/
void dispatch_matching_names(const char *zPrefix, Blob *pList){
  int i;
  int nPrefix = (int)strlen(zPrefix);
  for(i=FOSSIL_FIRST_CMD; i<MX_COMMAND; i++){
    if( strncmp(zPrefix, aCommand[i].zName, nPrefix)==0 ){
      blob_appendf(pList, " %s", aCommand[i].zName);
    }
  }
}

/*
** Return the index of the first non-space character that follows
** a span of two or more spaces.  Return 0 if there is not gap.
*/
static int hasGap(const char *z, int n){
  int i;
  for(i=3; i<n-1; i++){
    if( z[i]==' ' && z[i+1]!=' ' && z[i-1]==' ' && z[i-2]!='.' ) return i+1;
  }
  return 0 ;
}

/*
** Input string zIn starts with '['.  If the content is a hyperlink of the
** form [[...]] then return the index of the closing ']'.  Otherwise return 0.
*/
static int help_is_link(const char *z, int n){
  int i;
  char c;
  if( n<5 ) return 0;
  if( z[1]!='[' ) return 0;
  for(i=3; i<n && (c = z[i])!=0; i++){
    if( c==']' && z[i-1]==']' ) return i;
  }
  return 0;
}

/*
** Append text to pOut with changes:
**
**    *   Add hyperlink markup for [[...]]
**    *   Escape HTML characters: < > & and "
**    *   Change "%fossil" to just "fossil"
*/
static void appendLinked(Blob *pOut, const char *z, int n){
  int i = 0;
  int j;
  while( i<n ){
    char c = z[i];
    if( c=='[' && (j = help_is_link(z+i, n-i))>0 ){
      if( i ) blob_append(pOut, z, i);
      z += i+2;
      n -= i+2;
      blob_appendf(pOut, "<a href='%R/help?cmd=%.*s'>%.*s</a>",
         j-3, z, j-3, z);
      z += j-1;
      n -= j-1;
      i = 0;
    }else if( c=='%' && n-i>=7 && strncmp(z+i,"%fossil",7)==0 ){
      if( i ) blob_append(pOut, z, i);
      z += i+7;
      n -= i+7;
      blob_append(pOut, "fossil", 6);
      i = 0;
    }else if( c=='<' ){
      if( i ) blob_append(pOut, z, i);
      blob_append(pOut, "&lt;", 4);
      z += i+1;
      n -= i+1;
      i = 0;
    }else if( c=='>' ){
      if( i ) blob_append(pOut, z, i);
      blob_append(pOut, "&gt;", 4);
      z += i+1;
      n -= i+1;
      i = 0;
    }else if( c=='&' ){
      if( i ) blob_append(pOut, z, i);
      blob_append(pOut, "&amp;", 5);
      z += i+1;
      n -= i+1;
      i = 0;
    }else{
      i++;
    }
  }
  blob_append(pOut, z, i);
}

/*
** Append text to pOut, adding formatting markup.  Terms that
** have all lower-case letters are within <tt>..</tt>.  Terms
** that have all upper-case letters are within <i>..</i>.
*/
static void appendMixedFont(Blob *pOut, const char *z, int n){
  const char *zEnd = "";
  int i = 0;
  int j;
  while( i<n ){
    if( z[i]==' ' || z[i]=='=' ){
      for(j=i+1; j<n && (z[j]==' ' || z[j]=='='); j++){}
      appendLinked(pOut, z+i, j-i);
      i = j;
    }else{
      for(j=i; j<n && z[j]!=' ' && z[j]!='=' && !fossil_isalpha(z[j]); j++){}
      if( j>=n || z[j]==' ' || z[j]=='=' ){
        zEnd = "";
      }else{
        if( fossil_isupper(z[j]) && z[i]!='-' ){
          blob_append(pOut, "<i>",3);
          zEnd = "</i>";
        }else{
          blob_append(pOut, "<tt>", 4);
          zEnd = "</tt>";
        }
      }
      while( j<n && z[j]!=' ' && z[j]!='=' ){ j++; }
      appendLinked(pOut, z+i, j-i);
      if( zEnd[0] ) blob_append(pOut, zEnd, -1);
      i = j;
    }
  }
}

/*
** Attempt to reformat plain-text help into HTML for display on a webpage.
**
** The HTML output is appended to Blob pHtml, which should already be
** initialized.
**
** Formatting rules:
**
**   *  Bullet lists are indented from the surrounding text by
**      at least one space.  Each bullet begins with " * ".
**
**   *  Display lists are indented from the surrounding text.
**      Each tag begins with "-" or occur on a line that is
**      followed by two spaces and a non-space.  <dd> elements can begin
**      on the same line as long as they are separated by at least
**      two spaces.
**
**   *  Indented text is show verbatim (<pre>...</pre>)
*/
static void help_to_html(const char *zHelp, Blob *pHtml){
  int i;
  char c;
  int nIndent = 0;
  int wantP = 0;
  int wantBR = 0;
  int aIndent[10];
  const char *azEnd[10];
  int iLevel = 0;
  int isLI = 0;
  int isDT = 0;
  static const char *zEndDL = "</dl></blockquote>";
  static const char *zEndPRE = "</pre></blockquote>";
  static const char *zEndUL = "</ul>";
  static const char *zEndDD = "</dd>";

  aIndent[0] = 0;
  azEnd[0] = "";
  while( zHelp[0] ){
    i = 0;
    while( (c = zHelp[i])!=0 && c!='\n' ){
      if( c=='%' && i>2 && zHelp[i-2]==':' && strncmp(zHelp+i,"%fossil",7)==0 ){
        appendLinked(pHtml, zHelp, i);
        zHelp += i+1;
        i = 0;
        wantBR = 1;
        continue;
      }
      i++;
    }
    if( i>2 && zHelp[0]=='>' && zHelp[1]==' ' ){
      isDT = 1;
      for(nIndent=1; nIndent<i && zHelp[nIndent]==' '; nIndent++){}
    }else{
      isDT = 0;
      for(nIndent=0; nIndent<i && zHelp[nIndent]==' '; nIndent++){}
    }
    if( nIndent==i ){
      if( c==0 ) break;
      if( iLevel && azEnd[iLevel]==zEndPRE ){
        /* Skip the newline at the end of a <pre> */
      }else{
        blob_append_char(pHtml, '\n');
      }
      wantP = 1;
      wantBR = 0;
      zHelp += i+1;
      continue;
    }
    if( nIndent+2<i && zHelp[nIndent]=='*' && zHelp[nIndent+1]==' ' ){
      nIndent += 2;
      while( nIndent<i && zHelp[nIndent]==' '){ nIndent++; }
      isLI = 1;
    }else{
      isLI = 0;
    }
    while( iLevel>0 && aIndent[iLevel]>nIndent ){
      blob_append(pHtml, azEnd[iLevel--], -1);
    }
    if( nIndent>aIndent[iLevel] ){
      assert( iLevel<ArraySize(aIndent)-2 );
      if( isLI ){
        iLevel++;
        aIndent[iLevel] = nIndent;
        azEnd[iLevel] = zEndUL;
        blob_append(pHtml, "<ul>\n", 5);
      }else if( isDT 
             || zHelp[nIndent]=='-'
             || hasGap(zHelp+nIndent,i-nIndent) ){
        iLevel++;
        aIndent[iLevel] = nIndent;
        azEnd[iLevel] = zEndDL;
        blob_append(pHtml, "<blockquote><dl>\n", -1);
      }else if( azEnd[iLevel]==zEndDL ){
        iLevel++;
        aIndent[iLevel] = nIndent;
        azEnd[iLevel] = zEndDD;
        blob_append(pHtml, "<dd>", 4);
      }else if( wantP ){
        iLevel++;
        aIndent[iLevel] = nIndent;
        azEnd[iLevel] = zEndPRE;
        blob_append(pHtml, "<blockquote><pre>", -1);
        wantP = 0;
      }
    }
    if( isLI ){
      blob_append(pHtml, "<li> ", 5);
    }
    if( wantP ){
      blob_append(pHtml, "<p> ", 4);
      wantP = 0;
    }
    if( azEnd[iLevel]==zEndDL ){
      int iDD;
      blob_append(pHtml, "<dt> ", 5);
      iDD = hasGap(zHelp+nIndent, i-nIndent);
      if( iDD ){
        int x;
        assert( iLevel<ArraySize(aIndent)-1 );
        iLevel++;
        aIndent[iLevel] = x = nIndent+iDD;
        azEnd[iLevel] = zEndDD;
        appendMixedFont(pHtml, zHelp+nIndent, iDD-2);
        blob_append(pHtml, "</dt><dd>",9);
        appendLinked(pHtml, zHelp+x, i-x);
      }else{
        appendMixedFont(pHtml, zHelp+nIndent, i-nIndent);
      }
      blob_append(pHtml, "</dt>\n", 6);
    }else if( wantBR ){
      appendMixedFont(pHtml, zHelp+nIndent, i-nIndent);
      blob_append(pHtml, "<br>\n", 5);
      wantBR = 0;
    }else{
      appendLinked(pHtml, zHelp+nIndent, i-nIndent);
      blob_append_char(pHtml, '\n');
    }
    zHelp += i+1;
    i = 0;
    if( c==0 ) break;
  }
  while( iLevel>0 ){
    blob_appendf(pHtml, "%s\n", azEnd[iLevel--]);
  }
}

/*
** Format help text for TTY display.
*/
static void help_to_text(const char *zHelp, Blob *pText){
  int i, x;
  char c;
  for(i=0; (c = zHelp[i])!=0; i++){
    if( c=='%' && strncmp(zHelp+i,"%fossil",7)==0 ){
      if( i>0 ) blob_append(pText, zHelp, i);
      blob_append(pText, "fossil", 6);
      zHelp += i+7;
      i = -1;
      continue;
    }
    if( c=='\n' && strncmp(zHelp+i+1,"> ",2)==0 ){
      blob_append(pText, zHelp, i+1);
      blob_append(pText, " ", 1);
      zHelp += i+2;
      i = -1;
      continue;
    }
    if( c=='[' && (x = help_is_link(zHelp+i, 100000))!=0 ){
      if( i>0 ) blob_append(pText, zHelp, i);
      zHelp += i+2;
      blob_append(pText, zHelp, x-3);
      zHelp += x-1;
      i = -1;
      continue;
    }     
  }
  if( i>0 ){
    blob_append(pText, zHelp, i);
  }      
}

/*
** COMMAND: test-all-help
**
** Usage: %fossil test-all-help ?OPTIONS?
**
** Show help text for commands and pages.  Useful for proof-reading.
** Defaults to just the CLI commands.  Specify --www to see only the
** web pages, or --everything to see both commands and pages.
**
** Options:
**    -e|--everything   Show all commands and pages.
**    -t|--test         Include test- commands
**    -w|--www          Show WWW pages.
**    -s|--settings     Show settings.
**    -h|--html         Transform output to HTML.
**    -r|--raw          No output formatting.
*/
void test_all_help_cmd(void){
  int i;
  int mask = CMDFLAG_1ST_TIER | CMDFLAG_2ND_TIER;
  int useHtml = find_option("html","h",0)!=0;
  int rawOut = find_option("raw","r",0)!=0;

  if( find_option("www","w",0) ){
    mask = CMDFLAG_WEBPAGE;
  }
  if( find_option("everything","e",0) ){
    mask = CMDFLAG_1ST_TIER | CMDFLAG_2ND_TIER | CMDFLAG_WEBPAGE |
              CMDFLAG_SETTING | CMDFLAG_TEST;
  }
  if( find_option("settings","s",0) ){
    mask = CMDFLAG_SETTING;
  }
  if( find_option("test","t",0) ){
    mask |= CMDFLAG_TEST;
  }
  if( useHtml ) fossil_print("<!--\n");
  fossil_print("Help text for:\n");
  if( mask & CMDFLAG_1ST_TIER ) fossil_print(" * Commands\n");
  if( mask & CMDFLAG_2ND_TIER ) fossil_print(" * Auxiliary commands\n");
  if( mask & CMDFLAG_TEST )     fossil_print(" * Test commands\n");
  if( mask & CMDFLAG_WEBPAGE )  fossil_print(" * Web pages\n");
  if( mask & CMDFLAG_SETTING )  fossil_print(" * Settings\n");
  if( useHtml ){
    fossil_print("-->\n");
    fossil_print("<!-- start_all_help -->\n");
  }else{
    fossil_print("---\n");
  }
  for(i=0; i<MX_COMMAND; i++){
    if( (aCommand[i].eCmdFlags & mask)==0 ) continue;
    if( useHtml ){
      Blob html;
      blob_init(&html, 0, 0);
      help_to_html(aCommand[i].zHelp, &html);
      fossil_print("<h1>%h</h1>\n", aCommand[i].zName);
      fossil_print("%s\n<hr>\n", blob_str(&html));
      blob_reset(&html);
    }else if( rawOut ){
      fossil_print("# %s\n", aCommand[i].zName);
      fossil_print("%s\n\n", aCommand[i].zHelp);
    }else{
      Blob txt;
      blob_init(&txt, 0, 0);
      help_to_text(aCommand[i].zHelp, &txt);
      fossil_print("# %s\n", aCommand[i].zName);
      fossil_print("%s\n\n", blob_str(&txt));
      blob_reset(&txt);
    }
  }
  if( useHtml ){
    fossil_print("<!-- end_all_help -->\n");
  }else{
    fossil_print("---\n");
  }
  version_cmd();
}

/*
** Count the number of entries in the aCommand[] table that match
** the given flag.
*/
static int countCmds(unsigned int eFlg){
  int n = 0;
  int i;
  for(i=0; i<MX_COMMAND; i++){
    if( (aCommand[i].eCmdFlags & eFlg)!=0 ) n++;
  }
  return n;
}

/*
** COMMAND: test-command-stats
**
** Print statistics about the built-in command dispatch table.
*/
void test_command_stats_cmd(void){
  fossil_print("commands:       %4d\n",
     countCmds( CMDFLAG_COMMAND ));
  fossil_print("  1st tier         %4d\n",
     countCmds( CMDFLAG_1ST_TIER ));
  fossil_print("  2nd tier         %4d\n",
     countCmds( CMDFLAG_2ND_TIER ));
  fossil_print("  test             %4d\n",
     countCmds( CMDFLAG_TEST ));
  fossil_print("web-pages:      %4d\n",
     countCmds( CMDFLAG_WEBPAGE ));
  fossil_print("settings:       %4d\n",
     countCmds( CMDFLAG_SETTING ));
  fossil_print("total entries:  %4d\n", MX_COMMAND);
}

/*
** Compute an estimate of the edit-distance between to input strings.
**
** The first string is the input.  The second is the pattern.  Only the
** first 100 characters of the pattern are considered.
*/
static int edit_distance(const char *zA, const char *zB){
  int nA = (int)strlen(zA);
  int nB = (int)strlen(zB);
  int i, j, m;
  int p0, p1, c0;
  int a[100];
  static const int incr = 4;

  for(j=0; j<nB; j++) a[j] = 1;
  for(i=0; i<nA; i++){
    p0 = i==0 ? 0 : i*incr-1;
    c0 = i*incr;
    for(j=0; j<nB; j++){
      int m = 999;
      p1 = a[j];
      if( zA[i]==zB[j] ){
        m = p0;
      }else{
        m = c0+2;
        if( m>p1+2 ) m = p1+2;
        if( m>p0+3 ) m = p0+3;
      }
      c0 = a[j];
      a[j] = m;
      p0 = p1;
    }
  }
  m = a[nB-1];
  for(j=0; j<nB-1; j++){
    if( a[j]+1<m ) m = a[j]+1;
  }
  return m;
}

/*
** Fill the pointer array with names of commands that approximately
** match the input.  Return the number of approximate matches.
**
** Closest matches appear first.
*/
int dispatch_approx_match(const char *zIn, int nArray, const char **azArray){
  int i;
  int bestScore;
  int m;
  int n = 0;
  int mnScore = 0;
  int mxScore = 99999;
  int iFirst, iLast;

  if( zIn[0]=='/' ){
    iFirst = 0;
    iLast = FOSSIL_FIRST_CMD-1;
  }else{
    iFirst = FOSSIL_FIRST_CMD;
    iLast = MX_COMMAND-1;
  }

  while( n<nArray ){
    bestScore = mxScore;    
    for(i=iFirst; i<=iLast; i++){
      m = edit_distance(zIn, aCommand[i].zName);
      if( m<mnScore ) continue;
      if( m==mnScore ){
        azArray[n++] = aCommand[i].zName;
        if( n>=nArray ) return n;
       }else if( m<bestScore ){
        bestScore = m;
      }
    }
    if( bestScore>=mxScore ) break;
    mnScore = bestScore;
  }
  return n;
}

/*
** COMMAND: test-approx-match
**
** Test the approximate match algorithm
*/
void test_approx_match_command(void){
  int i, j, n;
  const char *az[20];
  for(i=2; i<g.argc; i++){
    fossil_print("%s:\n", g.argv[i]);
    n = dispatch_approx_match(g.argv[i], 20, az);
    for(j=0; j<n; j++){
      fossil_print("   %s\n", az[j]);
    }
  }
}

/*
** WEBPAGE: help
** URL: /help?name=CMD
**
** Show the built-in help text for CMD.  CMD can be a command-line interface
** command or a page name from the web interface or a setting.
** Query parameters:
**
**    name=CMD        Show help for CMD where CMD is a command name or
**                    webpage name or setting name.
**
**    plaintext       Show the help within <pre>...</pre>, as if it were
**                    displayed using the "fossil help" command.
**
**    raw             Show the raw help text without any formatting.
**                    (Used for debugging.)
*/
void help_page(void){
  const char *zCmd = P("cmd");

  if( zCmd==0 ) zCmd = P("name");
  if( zCmd && *zCmd ){
    int rc;
    const CmdOrPage *pCmd = 0;

    style_header("Help: %s", zCmd);

    style_submenu_element("Command-List", "%s/help", g.zTop);
    rc = dispatch_name_search(zCmd, CMDFLAG_ANY|CMDFLAG_PREFIX, &pCmd);
    if( *zCmd=='/' ){
      /* Some of the webpages require query parameters in order to work.
      ** @ <h1>The "<a href='%R%s(zCmd)'>%s(zCmd)</a>" page:</h1> */
      @ <h1>The "%h(zCmd)" page:</h1>
    }else if( rc==0 && (pCmd->eCmdFlags & CMDFLAG_SETTING)!=0 ){
      @ <h1>The "%h(pCmd->zName)" setting:</h1>
    }else{
      @ <h1>The "%h(zCmd)" command:</h1>
    }
    if( rc==1 ){
      @ unknown command: %h(zCmd)
    }else if( rc==2 ){
      @ ambiguous command prefix: %h(zCmd)
    }else{
      if( pCmd->zHelp[0]==0 ){
        @ No help available for "%h(pCmd->zName)"
      }else if( P("plaintext") ){
        Blob txt;
        blob_init(&txt, 0, 0);
        help_to_text(pCmd->zHelp, &txt);
        @ <pre class="helpPage">
        @ %h(blob_str(&txt))
        @ </pre>
        blob_reset(&txt);
      }else if( P("raw") ){
        @ <pre class="helpPage">
        @ %h(pCmd->zHelp)
        @ </pre>
      }else{
        @ <div class="helpPage">
        help_to_html(pCmd->zHelp, cgi_output_blob());
        @ </div>
      }
    }
  }else{
    int i;

    style_header("Help");

    @ <a name='commands'></a>
    @ <h1>Available commands:</h1>
    @ <div class="columns" style="column-width: 12ex;">
    @ <ul>
    for(i=0; i<MX_COMMAND; i++){
      const char *z = aCommand[i].zName;
      const char *zBoldOn  = aCommand[i].eCmdFlags&CMDFLAG_1ST_TIER?"<b>" :"";
      const char *zBoldOff = aCommand[i].eCmdFlags&CMDFLAG_1ST_TIER?"</b>":"";
      if( '/'==*z || strncmp(z,"test",4)==0 ) continue;
      if( (aCommand[i].eCmdFlags & CMDFLAG_SETTING)!=0 ) continue;
      @ <li><a href="%R/help?cmd=%s(z)">%s(zBoldOn)%s(z)%s(zBoldOff)</a></li>
    }
    @ </ul></div>

    @ <a name='webpages'></a>
    @ <h1>Available web UI pages:</h1>
    @ <div class="columns" style="column-width: 18ex;">
    @ <ul>
    for(i=0; i<MX_COMMAND; i++){
      const char *z = aCommand[i].zName;
      if( '/'!=*z ) continue;
      if( aCommand[i].zHelp[0] ){
        @ <li><a href="%R/help?cmd=%s(z)">%s(z+1)</a></li>
      }else{
        @ <li>%s(z+1)</li>
      }
    }
    @ </ul></div>

    @ <a name='unsupported'></a>
    @ <h1>Unsupported commands:</h1>
    @ <div class="columns" style="column-width: 20ex;">
    @ <ul>
    for(i=0; i<MX_COMMAND; i++){
      const char *z = aCommand[i].zName;
      if( strncmp(z,"test",4)!=0 ) continue;
      if( aCommand[i].zHelp[0] ){
        @ <li><a href="%R/help?cmd=%s(z)">%s(z)</a></li>
      }else{
        @ <li>%s(z)</li>
      }
    }
    @ </ul></div>

    @ <a name='settings'></a>
    @ <h1>Settings:</h1>
    @ <div class="columns" style="column-width: 20ex;">
    @ <ul>
    for(i=0; i<MX_COMMAND; i++){
      const char *z = aCommand[i].zName;
      if( (aCommand[i].eCmdFlags & CMDFLAG_SETTING)==0 ) continue;
      if( aCommand[i].zHelp[0] ){
        @ <li><a href="%R/help?cmd=%s(z)">%s(z)</a></li>
      }else{
        @ <li>%s(z)</li>
      }
    }
    @ </ul></div>

  }
  style_footer();
}

/*
** WEBPAGE: test-all-help
**
** Show all help text on a single page.  Useful for proof-reading.
*/
void test_all_help_page(void){
  int i;
  Blob buf;
  blob_init(&buf,0,0);
  style_header("All Help Text");
  @ <dl>
  for(i=0; i<MX_COMMAND; i++){
    const char *zDesc;
    unsigned int e = aCommand[i].eCmdFlags;
    if( e & CMDFLAG_1ST_TIER ){
      zDesc = "1st tier command";
    }else if( e & CMDFLAG_2ND_TIER ){
      zDesc = "2nd tier command";
    }else if( e & CMDFLAG_TEST ){
      zDesc = "test command";
    }else if( e & CMDFLAG_WEBPAGE ){
      if( e & CMDFLAG_RAWCONTENT ){
        zDesc = "raw-content web page";
      }else{
        zDesc = "web page";
      }
    }else{
      blob_reset(&buf);
      if( e & CMDFLAG_VERSIONABLE ){
        blob_appendf(&buf, "versionable ");
      }
      if( e & CMDFLAG_BLOCKTEXT ){
        blob_appendf(&buf, "block-text ");
      }
      if( e & CMDFLAG_BOOLEAN ){
        blob_appendf(&buf, "boolean ");
      }
      blob_appendf(&buf,"setting");
      zDesc = blob_str(&buf);
    }
    if( memcmp(aCommand[i].zName, "test", 4)==0 ) continue;
    @ <dt><big><b>%s(aCommand[i].zName)</b></big> (%s(zDesc))</dt>
    @ <dd>
    help_to_html(aCommand[i].zHelp, cgi_output_blob());
    @ </dd>
  }
  @ </dl>
  blob_reset(&buf);
  style_footer();
}

static void multi_column_list(const char **azWord, int nWord){
  int i, j, len;
  int mxLen = 0;
  int nCol;
  int nRow;
  for(i=0; i<nWord; i++){
    len = strlen(azWord[i]);
    if( len>mxLen ) mxLen = len;
  }
  nCol = 80/(mxLen+2);
  if( nCol==0 ) nCol = 1;
  nRow = (nWord + nCol - 1)/nCol;
  for(i=0; i<nRow; i++){
    const char *zSpacer = "";
    for(j=i; j<nWord; j+=nRow){
      fossil_print("%s%-*s", zSpacer, mxLen, azWord[j]);
      zSpacer = "  ";
    }
    fossil_print("\n");
  }
}

/*
** COMMAND: test-list-webpage
**
** List all web pages.
*/
void cmd_test_webpage_list(void){
  int i, nCmd;
  const char *aCmd[MX_COMMAND];
  for(i=nCmd=0; i<MX_COMMAND; i++){
    if(CMDFLAG_WEBPAGE & aCommand[i].eCmdFlags){
      aCmd[nCmd++] = aCommand[i].zName;
    }
  }
  assert(nCmd && "page list is empty?");
  multi_column_list(aCmd, nCmd);
}


/*
** List of commands starting with zPrefix, or all commands if zPrefix is NULL.
*/
static void command_list(const char *zPrefix, int cmdMask){
  int i, nCmd;
  int nPrefix = zPrefix ? strlen(zPrefix) : 0;
  const char *aCmd[MX_COMMAND];
  for(i=nCmd=0; i<MX_COMMAND; i++){
    const char *z = aCommand[i].zName;
    if( (aCommand[i].eCmdFlags & cmdMask)==0 ) continue;
    if( zPrefix && memcmp(zPrefix, z, nPrefix)!=0 ) continue;
    aCmd[nCmd++] = aCommand[i].zName;
  }
  multi_column_list(aCmd, nCmd);
}

/*
** Documentation on universal command-line options.
*/
/* @-comment: # */
static const char zOptions[] =
@ Command-line options common to all commands:
@ 
@   --args FILENAME         Read additional arguments and options from FILENAME
@   --cgitrace              Active CGI tracing
@   --comfmtflags VALUE     Set comment formatting flags to VALUE
@   --comment-format VALUE  Alias for --comfmtflags
@   --errorlog FILENAME     Log errors to FILENAME 
@   --help                  Show help on the command rather than running it
@   --httptrace             Trace outbound HTTP requests
@   --localtime             Display times using the local timezone
@   --no-th-hook            Do not run TH1 hooks
@   --quiet                 Reduce the amount of output
@   --sqlstats              Show SQL usage statistics when done
@   --sqltrace              Trace all SQL commands
@   --sshtrace              Trace SSH activity
@   --ssl-identity NAME     Set the SSL identity to NAME
@   --systemtrace           Trace calls to system()
@   --user|-U USER          Make the default user be USER
@   --utc                   Display times using UTC
@   --vfs NAME              Cause SQLite to use the NAME VFS
;

/*
** COMMAND: help
**
** Usage: %fossil help [OPTIONS] [TOPIC]
**
** Display information on how to use TOPIC, which may be a command, webpage, or
** setting.  Webpage names begin with "/".  If TOPIC is omitted, a list of
** topics is returned.
**
** The following options can be used when TOPIC is omitted:
**
**    -a|--all          List both common and auxiliary commands
**    -o|--options      List command-line options common to all commands
**    -s|--setting      List setting names
**    -t|--test         List unsupported "test" commands
**    -x|--aux          List only auxiliary commands
**    -w|--www          List all web pages
**
** These options can be used when TOPIC is present:
**
**    -h|--html         Format output as HTML rather than plain text
*/
void help_cmd(void){
  int rc;
  int isPage = 0;
  const char *z;
  const char *zCmdOrPage;
  const CmdOrPage *pCmd = 0;
  int useHtml = 0;
  Blob txt;
  if( g.argc<3 ){
    z = g.argv[0];
    fossil_print(
      "Usage: %s help TOPIC\n"
      "Try \"%s help help\" or \"%s help -a\" for more options\n"
      "Frequently used commands:\n",
      z, z, z);
    command_list(0, CMDFLAG_1ST_TIER);
    version_cmd();
    return;
  }
  if( find_option("options","o",0) ){
    fossil_print("%s", zOptions);
    return;
  }
  if( find_option("all","a",0) ){
    command_list(0, CMDFLAG_1ST_TIER | CMDFLAG_2ND_TIER);
    return;
  }
  else if( find_option("www","w",0) ){
    command_list(0, CMDFLAG_WEBPAGE);
    return;
  }
  else if( find_option("aux","x",0) ){
    command_list(0, CMDFLAG_2ND_TIER);
    return;
  }
  else if( find_option("test","t",0) ){
    command_list(0, CMDFLAG_TEST);
    return;
  }
  else if( find_option("setting","s",0) ){
    command_list(0, CMDFLAG_SETTING);
    return;
  }
  useHtml = find_option("html","h",0)!=0;
  isPage = ('/' == *g.argv[2]) ? 1 : 0;
  if(isPage){
    zCmdOrPage = "page";
  }else{
    zCmdOrPage = "command or setting";
  }
  rc = dispatch_name_search(g.argv[2], CMDFLAG_ANY|CMDFLAG_PREFIX, &pCmd);
  if( rc ){
    int i, n;
    const char *az[5];
    if( rc==1 ){
      fossil_print("unknown %s: %s\n", zCmdOrPage, g.argv[2]);
    }else{
      fossil_print("ambiguous %s prefix: %s\n",
                 zCmdOrPage, g.argv[2]);
    }
    fossil_print("Did you mean one of:\n");
    n = dispatch_approx_match(g.argv[2], 5, az);
    for(i=0; i<n; i++){
      fossil_print("  *  %s\n", az[i]);
    }
    fossil_print("Also consider using:\n");
    fossil_print("   fossil help -a     ;# show all commands\n");
    fossil_print("   fossil help -w     ;# show all web-pages\n");
    fossil_print("   fossil help -s     ;# show all settings\n");
    fossil_exit(1);
  }
  z = pCmd->zHelp;
  if( z==0 ){
    fossil_fatal("no help available for the %s %s",
                 pCmd->zName, zCmdOrPage);
  }
  if( pCmd->eCmdFlags & CMDFLAG_SETTING ){
    fossil_print("Setting: \"%s\"%s\n\n",
         pCmd->zName,
         (pCmd->eCmdFlags & CMDFLAG_VERSIONABLE)!=0 ? " (versionable)" : ""
    );
  }
  blob_init(&txt, 0, 0);
  if( useHtml ){
    help_to_html(z, &txt);
  }else{
    help_to_text(z, &txt);
  }
  fossil_print("%s\n", blob_str(&txt));
  blob_reset(&txt);
}

/*
** Return a pointer to the setting information array.
**
** This routine provides access to the aSetting2[] array which is created
** by the mkindex utility program and included with <page_index.h>.
*/
const Setting *setting_info(int *pnCount){
  if( pnCount ) *pnCount = (int)(sizeof(aSetting)/sizeof(aSetting[0])) - 1;
  return aSetting;
}

/*****************************************************************************
** A virtual table for accessing the information in aCommand[], and
** especially the help-text
*/

/* helptextVtab_vtab is a subclass of sqlite3_vtab which is
** underlying representation of the virtual table
*/
typedef struct helptextVtab_vtab helptextVtab_vtab;
struct helptextVtab_vtab {
  sqlite3_vtab base;  /* Base class - must be first */
  /* Add new fields here, as necessary */
};

/* helptextVtab_cursor is a subclass of sqlite3_vtab_cursor which will
** serve as the underlying representation of a cursor that scans
** over rows of the result
*/
typedef struct helptextVtab_cursor helptextVtab_cursor;
struct helptextVtab_cursor {
  sqlite3_vtab_cursor base;  /* Base class - must be first */
  /* Insert new fields here.  For this helptextVtab we only keep track
  ** of the rowid */
  sqlite3_int64 iRowid;      /* The rowid */
};

/*
** The helptextVtabConnect() method is invoked to create a new
** helptext virtual table.
**
** Think of this routine as the constructor for helptextVtab_vtab objects.
**
** All this routine needs to do is:
**
**    (1) Allocate the helptextVtab_vtab object and initialize all fields.
**
**    (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the
**        result set of queries against the virtual table will look like.
*/
static int helptextVtabConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  helptextVtab_vtab *pNew;
  int rc;

  rc = sqlite3_declare_vtab(db,
           "CREATE TABLE x(name,type,flags,helptext,formatted,html)"
       );
  if( rc==SQLITE_OK ){
    pNew = sqlite3_malloc( sizeof(*pNew) );
    *ppVtab = (sqlite3_vtab*)pNew;
    if( pNew==0 ) return SQLITE_NOMEM;
    memset(pNew, 0, sizeof(*pNew));
  }
  return rc;
}

/*
** This method is the destructor for helptextVtab_vtab objects.
*/
static int helptextVtabDisconnect(sqlite3_vtab *pVtab){
  helptextVtab_vtab *p = (helptextVtab_vtab*)pVtab;
  sqlite3_free(p);
  return SQLITE_OK;
}

/*
** Constructor for a new helptextVtab_cursor object.
*/
static int helptextVtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  helptextVtab_cursor *pCur;
  pCur = sqlite3_malloc( sizeof(*pCur) );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur));
  *ppCursor = &pCur->base;
  return SQLITE_OK;
}

/*
** Destructor for a helptextVtab_cursor.
*/
static int helptextVtabClose(sqlite3_vtab_cursor *cur){
  helptextVtab_cursor *pCur = (helptextVtab_cursor*)cur;
  sqlite3_free(pCur);
  return SQLITE_OK;
}


/*
** Advance a helptextVtab_cursor to its next row of output.
*/
static int helptextVtabNext(sqlite3_vtab_cursor *cur){
  helptextVtab_cursor *pCur = (helptextVtab_cursor*)cur;
  pCur->iRowid++;
  return SQLITE_OK;
}

/*
** Return values of columns for the row at which the helptextVtab_cursor
** is currently pointing.
*/
static int helptextVtabColumn(
  sqlite3_vtab_cursor *cur,   /* The cursor */
  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
  int i                       /* Which column to return */
){
  helptextVtab_cursor *pCur = (helptextVtab_cursor*)cur;
  const CmdOrPage *pPage = aCommand + pCur->iRowid;
  switch( i ){
    case 0:  /* name */
      sqlite3_result_text(ctx, pPage->zName, -1, SQLITE_STATIC);
      break;
    case 1: { /* type */
      const char *zType = 0;
      if( pPage->eCmdFlags & CMDFLAG_COMMAND ){
        zType = "command";
      }else if( pPage->eCmdFlags & CMDFLAG_WEBPAGE ){
        zType = "webpage";
      }else if( pPage->eCmdFlags & CMDFLAG_SETTING ){
        zType = "setting";
      }
      sqlite3_result_text(ctx, zType, -1, SQLITE_STATIC);
      break;
    }
    case 2:  /* flags */
      sqlite3_result_int(ctx, pPage->eCmdFlags);
      break;
    case 3:  /* helptext */
      sqlite3_result_text(ctx, pPage->zHelp, -1, SQLITE_STATIC);
      break;
    case 4: { /* formatted */
      Blob txt;
      blob_init(&txt, 0, 0);
      help_to_text(pPage->zHelp, &txt);
      sqlite3_result_text(ctx, blob_str(&txt), -1, fossil_free);
      break;
    }
    case 5: { /* formatted */
      Blob txt;
      blob_init(&txt, 0, 0);
      help_to_html(pPage->zHelp, &txt);
      sqlite3_result_text(ctx, blob_str(&txt), -1, fossil_free);
      break;
    }
  }
  return SQLITE_OK;
}

/*
** Return the rowid for the current row.  In this implementation, the
** rowid is the same as the output value.
*/
static int helptextVtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  helptextVtab_cursor *pCur = (helptextVtab_cursor*)cur;
  *pRowid = pCur->iRowid;
  return SQLITE_OK;
}

/*
** Return TRUE if the cursor has been moved off of the last
** row of output.
*/
static int helptextVtabEof(sqlite3_vtab_cursor *cur){
  helptextVtab_cursor *pCur = (helptextVtab_cursor*)cur;
  return pCur->iRowid>=MX_COMMAND;
}

/*
** This method is called to "rewind" the helptextVtab_cursor object back
** to the first row of output.  This method is always called at least
** once prior to any call to helptextVtabColumn() or helptextVtabRowid() or 
** helptextVtabEof().
*/
static int helptextVtabFilter(
  sqlite3_vtab_cursor *pVtabCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  helptextVtab_cursor *pCur = (helptextVtab_cursor *)pVtabCursor;
  pCur->iRowid = 1;
  return SQLITE_OK;
}

/*
** SQLite will invoke this method one or more times while planning a query
** that uses the virtual table.  This routine needs to create
** a query plan for each invocation and compute an estimated cost for that
** plan.
*/
static int helptextVtabBestIndex(
  sqlite3_vtab *tab,
  sqlite3_index_info *pIdxInfo
){
  pIdxInfo->estimatedCost = (double)MX_COMMAND;
  pIdxInfo->estimatedRows = MX_COMMAND;
  return SQLITE_OK;
}

/*
** This following structure defines all the methods for the 
** virtual table.
*/
static sqlite3_module helptextVtabModule = {
  /* iVersion    */ 0,
  /* xCreate     */ 0,  /* Helptext is eponymous and read-only */
  /* xConnect    */ helptextVtabConnect,
  /* xBestIndex  */ helptextVtabBestIndex,
  /* xDisconnect */ helptextVtabDisconnect,
  /* xDestroy    */ 0,
  /* xOpen       */ helptextVtabOpen,
  /* xClose      */ helptextVtabClose,
  /* xFilter     */ helptextVtabFilter,
  /* xNext       */ helptextVtabNext,
  /* xEof        */ helptextVtabEof,
  /* xColumn     */ helptextVtabColumn,
  /* xRowid      */ helptextVtabRowid,
  /* xUpdate     */ 0,
  /* xBegin      */ 0,
  /* xSync       */ 0,
  /* xCommit     */ 0,
  /* xRollback   */ 0,
  /* xFindMethod */ 0,
  /* xRename     */ 0,
  /* xSavepoint  */ 0,
  /* xRelease    */ 0,
  /* xRollbackTo */ 0,
  /* xShadowName */ 0
};


/*
** Register the helptext virtual table
*/
int helptext_vtab_register(sqlite3 *db){
  int rc = sqlite3_create_module(db, "helptext", &helptextVtabModule, 0);
  return rc;
}
/* End of the helptext virtual table
******************************************************************************/