#!/usr/bin/tclsh.docsrc
#### Import of wapp.tcl
# Copyright (c) 2017 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.
#
#---------------------------------------------------------------------------
#
# Design rules:
#
#   (1)  All identifiers in the global namespace begin with "wapp"
#
#   (2)  Indentifiers intended for internal use only begin with "wappInt"
#

# Add text to the end of the HTTP reply.  No interpretation or transformation
# of the text is performs.  The argument should be enclosed within {...}
#
proc wapp {txt} {
  global wapp
  dict append wapp .reply $txt
}

# Add text to the page under construction.  Do no escaping on the text.
#
# Though "unsafe" in general, there are uses for this kind of thing.
# For example, if you want to return the complete, unmodified content of
# a file:
#
#         set fd [open content.html rb]
#         wapp-unsafe [read $fd]
#         close $fd
#
# You could do the same thing using ordinary "wapp" instead of "wapp-unsafe".
# The difference is that wapp-safety-check will complain about the misuse
# of "wapp", but it assumes that the person who write "wapp-unsafe" understands
# the risks.
#
# Though occasionally necessary, the use of this interface should be minimized.
#
proc wapp-unsafe {txt} {
  global wapp
  dict append wapp .reply $txt
}

# Add text to the end of the reply under construction.  The following
# substitutions are made:
#
#     %html(...)          Escape text for inclusion in HTML
#     %url(...)           Escape text for use as a URL
#     %qp(...)            Escape text for use as a URI query parameter
#     %string(...)        Escape text for use within a JSON string
#     %unsafe(...)        No transformations of the text
#
# The substitutions above terminate at the first ")" character.  If the
# text of the TCL string in ... contains ")" characters itself, use instead:
#
#     %html%(...)%
#     %url%(...)%
#     %qp%(...)%
#     %string%(...)%
#     %unsafe%(...)%
#
# In other words, use "%(...)%" instead of "(...)" to include the TCL string
# to substitute.
#
# The %unsafe substitution should be avoided whenever possible, obviously.
# In addition to the substitutions above, the text also does backslash
# escapes.
#
proc wapp-subst {txt} {
  global wapp
  regsub -all {%(html|url|qp|string|unsafe){1,1}?(|%)\((.+)\)\2} $txt \
         {[wappInt-enc-\1 "\3"]} txt
  dict append wapp .reply [uplevel 1 [list subst -novariables $txt]]
}

# Works like wapp-subst, but also removes whitespace from the beginning
# of lines.
#
proc wapp-trim {txt} {
  global wapp
  regsub -all {\n\s+} [string trim $txt] \n txt
  regsub -all {%(html|url|qp|string|unsafe){1,1}?(|%)\((.+)\)\2} $txt \
         {[wappInt-enc-\1 "\3"]} txt
  dict append wapp .reply [uplevel 1 [list subst -novariables $txt]]
}

# There must be a wappInt-enc-NAME routine for each possible substitution
# in wapp-subst.  Thus there are routines for "html", "url", "qp", and "unsafe".
#
#    wappInt-enc-html           Escape text so that it is safe to use in the
#                               body of an HTML document.
#
#    wappInt-enc-url            Escape text so that it is safe to pass as an
#                               argument to href= and src= attributes in HTML.
#
#    wappInt-enc-qp             Escape text so that it is safe to use as the
#                               value of a query parameter in a URL or in
#                               post data or in a cookie.
#
#    wappInt-enc-string         Escape ", ', \, and < for using inside of a
#                               javascript string literal.  The < character
#                               is escaped to prevent "</script>" from causing
#                               problems in embedded javascript.
#
#    wappInt-enc-unsafe         Perform no encoding at all.  Unsafe.
#
proc wappInt-enc-html {txt} {
  return [string map {& &amp; < &lt; > &gt; \" &quot; \\ &#92;} $txt]
}
proc wappInt-enc-unsafe {txt} {
  return $txt
}
proc wappInt-enc-url {s} {
  if {[regsub -all {[^-{}@~?=#_.:/a-zA-Z0-9]} $s {[wappInt-%HHchar {&}]} s]} {
    set s [subst -novar -noback $s]
  }
  if {[regsub -all {[{}]} $s {[wappInt-%HHchar \\&]} s]} {
    set s [subst -novar -noback $s]
  }
  return $s
}
proc wappInt-enc-qp {s} {
  if {[regsub -all {[^-{}_.a-zA-Z0-9]} $s {[wappInt-%HHchar {&}]} s]} {
    set s [subst -novar -noback $s]
  }
  if {[regsub -all {[{}]} $s {[wappInt-%HHchar \\&]} s]} {
    set s [subst -novar -noback $s]
  }
  return $s
}
proc wappInt-enc-string {s} {
  return [string map {\\ \\\\ \" \\\" ' \\' < \\u003c} $s]
}

# This is a helper routine for wappInt-enc-url and wappInt-enc-qp.  It returns
# an appropriate %HH encoding for the single character c.  If c is a unicode
# character, then this routine might return multiple bytes:  %HH%HH%HH
#
proc wappInt-%HHchar {c} {
  if {$c==" "} {return +}
  return [regsub -all .. [binary encode hex [encoding convertto utf-8 $c]] {%&}]
}


# Undo the www-url-encoded format.
#
# HT: This code stolen from ncgi.tcl
#
proc wappInt-decode-url {str} {
  set str [string map [list + { } "\\" "\\\\" \[ \\\[ \] \\\]] $str]
  regsub -all -- \
      {%([Ee][A-Fa-f0-9])%([89ABab][A-Fa-f0-9])%([89ABab][A-Fa-f0-9])} \
      $str {[encoding convertfrom utf-8 [binary decode hex \1\2\3]]} str
  regsub -all -- \
      {%([CDcd][A-Fa-f0-9])%([89ABab][A-Fa-f0-9])}                     \
      $str {[encoding convertfrom utf-8 [binary decode hex \1\2]]} str
  regsub -all -- {%([0-7][A-Fa-f0-9])} $str {\\u00\1} str
  return [subst -novar $str]
}

# Reset the document back to an empty string.
#
proc wapp-reset {} {
  global wapp
  dict set wapp .reply {}
}

# Change the mime-type of the result document.
#
proc wapp-mimetype {x} {
  global wapp
  dict set wapp .mimetype $x
}

# Change the reply code.
#
proc wapp-reply-code {x} {
  global wapp
  dict set wapp .reply-code $x
}

# Set a cookie
#
proc wapp-set-cookie {name value} {
  global wapp
  dict lappend wapp .new-cookies $name $value
}

# Unset a cookie
#
proc wapp-clear-cookie {name} {
  wapp-set-cookie $name {}
}

# Add extra entries to the reply header
#
proc wapp-reply-extra {name value} {
  global wapp
  dict lappend wapp .reply-extra $name $value
}

# Specifies how the web-page under construction should be cached.
# The argument should be one of:
#
#    no-cache
#    max-age=N             (for some integer number of seconds, N)
#    private,max-age=N
#
proc wapp-cache-control {x} {
  wapp-reply-extra Cache-Control $x
}

# Redirect to a different web page
#
proc wapp-redirect {uri} {
  wapp-reply-code {307 Redirect}
  wapp-reply-extra Location $uri
}

# Return the value of a wapp parameter
#
proc wapp-param {name {dflt {}}} {
  global wapp
  if {![dict exists $wapp $name]} {return $dflt}
  return [dict get $wapp $name]
}

# Return true if a and only if the wapp parameter $name exists
#
proc wapp-param-exists {name} {
  global wapp
  return [dict exists $wapp $name]
}

# Set the value of a wapp parameter
#
proc wapp-set-param {name value} {
  global wapp
  dict set wapp $name $value
}

# Return all parameter names that match the GLOB pattern, or all
# names if the GLOB pattern is omitted.
#
proc wapp-param-list {{glob {*}}} {
  global wapp
  return [dict keys $wapp $glob]
}

# By default, Wapp does not decode query parameters and POST parameters
# for cross-origin requests.  This is a security restriction, designed to
# help prevent cross-site request forgery (CSRF) attacks.
#
# As a consequence of this restriction, URLs for sites generated by Wapp
# that contain query parameters will not work as URLs found in other
# websites.  You cannot create a link from a second website into a Wapp
# website if the link contains query planner, by default.
#
# Of course, it is sometimes desirable to allow query parameters on external
# links.  For URLs for which this is safe, the application should invoke
# wapp-allow-xorigin-params.  This procedure tells Wapp that it is safe to
# go ahead and decode the query parameters even for cross-site requests.
#
# In other words, for Wapp security is the default setting.  Individual pages
# need to actively disable the cross-site request security if those pages
# are safe for cross-site access.
#
proc wapp-allow-xorigin-params {} {
  global wapp
  if {![dict exists $wapp .qp] && ![dict get $wapp SAME_ORIGIN]} {
    wappInt-decode-query-params
  }
}

# Set the content-security-policy.
#
# The default content-security-policy is very strict:  "default-src 'self'"
# The default policy prohibits the use of in-line javascript or CSS.
#
# Provide an alternative CSP as the argument.  Or use "off" to disable
# the CSP completely.
#
proc wapp-content-security-policy {val} {
  global wapp
  if {$val=="off"} {
    dict unset wapp .csp
  } else {
    dict set wapp .csp $val
  }
}

# Examine the bodys of all procedures in this program looking for
# unsafe calls to various Wapp interfaces.  Return a text string
# containing warnings. Return an empty string if all is ok.
#
# This routine is advisory only.  It misses some constructs that are
# dangerous and flags others that are safe.
#
proc wapp-safety-check {} {
  set res {}
  foreach p [info procs] {
    set ln 0
    foreach x [split [info body $p] \n] {
      incr ln
      if {[regexp {^[ \t]*wapp[ \t]+([^\n]+)} $x all tail]
       && [string index $tail 0]!="\173"
       && [regexp {[[$]} $tail]
      } {
        append res "$p:$ln: unsafe \"wapp\" call: \"[string trim $x]\"\n"
      }
      if {[regexp {^[ \t]*wapp-(subst|trim)[ \t]+[^\173]} $x all cx]} {
        append res "$p:$ln: unsafe \"wapp-$cx\" call: \"[string trim $x]\"\n"
      }
    }
  }
  return $res
}

# Return a string that descripts the current environment.  Applications
# might find this useful for debugging.
#
proc wapp-debug-env {} {
  global wapp
  set out {}
  foreach var [lsort [dict keys $wapp]] {
    if {[string index $var 0]=="."} continue
    append out "$var = [list [dict get $wapp $var]]\n"
  }
  append out "\[pwd\] = [list [pwd]]\n"
  return $out
}

# Tracing function for each HTTP request.  This is overridden by wapp-start
# if tracing is enabled.
#
proc wappInt-trace {} {}

# Start up a listening socket.  Arrange to invoke wappInt-new-connection
# for each inbound HTTP connection.
#
#    port            Listen on this TCP port.  0 means to select a port
#                    that is not currently in use
#
#    wappmode        One of "scgi", "server", or "local".
#
proc wappInt-start-listener {port wappmode} {
  if {$wappmode=="scgi"} {
    set type SCGI
    set server [list wappInt-new-connection wappInt-scgi-readable $wappmode]
  } else {
    set type HTTP
    set server [list wappInt-new-connection wappInt-http-readable $wappmode]
  }
  if {$wappmode=="local"} {
    set x [socket -server $server -myaddr 127.0.0.1 $port]
  } else {
    set x [socket -server $server $port]
  }
  set coninfo [chan configure $x -sockname]
  set port [lindex $coninfo 2]
  if {$wappmode=="local"} {
    wappInt-start-browser http://127.0.0.1:$port/
  } else {
    puts "Listening for $type requests on TCP port $port"
  }
}

# Start a web-browser and point it at $URL
#
proc wappInt-start-browser {url} {
  global tcl_platform
  if {$tcl_platform(platform)=="windows"} {
    exec cmd /c start $url &
  } elseif {$tcl_platform(os)=="Darwin"} {
    exec open $url &
  } elseif {[catch {exec xdg-open $url}]} {
    exec firefox $url &
  }
}

# This routine is a "socket -server" callback.  The $chan, $ip, and $port
# arguments are added by the socket command.
#
# Arrange to invoke $callback when content is available on the new socket.
# The $callback will process inbound HTTP or SCGI content.
#
proc wappInt-new-connection {callback wappmode chan ip port} {
  upvar #0 wappInt-$chan W
  set W [dict create REMOTE_ADDR $ip REMOTE_PORT $port WAPP_MODE $wappmode \
         .header {}]
  fconfigure $chan -blocking 0 -translation binary
  fileevent $chan readable [list $callback $chan]
}

# Close an input channel
#
proc wappInt-close-channel {chan} {
  if {$chan=="stdout"} {
    # This happens after completing a CGI request
    exit 0
  } else {
    unset ::wappInt-$chan
    close $chan
  }
}

# Process new text received on an inbound HTTP request
#
proc wappInt-http-readable {chan} {
  if {[catch [list wappInt-http-readable-unsafe $chan] msg]} {
    puts stderr "$msg\n$::errorInfo"
    wappInt-close-channel $chan
  }
}
proc wappInt-http-readable-unsafe {chan} {
  upvar #0 wappInt-$chan W wapp wapp
  if {![dict exists $W .toread]} {
    # If the .toread key is not set, that means we are still reading
    # the header
    set line [string trimright [gets $chan]]
    set n [string length $line]
    if {$n>0} {
      if {[dict get $W .header]=="" || [regexp {^\s+} $line]} {
        dict append W .header $line
      } else {
        dict append W .header \n$line
      }
      if {[string length [dict get $W .header]]>100000} {
        error "HTTP request header too big - possible DOS attack"
      }
    } elseif {$n==0} {
      # We have reached the blank line that terminates the header.
      global argv0
      set a0 [file normalize $argv0]
      dict set W SCRIPT_FILENAME $a0
      dict set W DOCUMENT_ROOT [file dir $a0]
      if {[wappInt-parse-header $chan]} {
        catch {close $chan}
        return
      }
      set len 0
      if {[dict exists $W CONTENT_LENGTH]} {
        set len [dict get $W CONTENT_LENGTH]
      }
      if {$len>0} {
        # Still need to read the query content
        dict set W .toread $len
      } else {
        # There is no query content, so handle the request immediately
        set wapp $W
        wappInt-handle-request $chan 0
      }
    }
  } else {
    # If .toread is set, that means we are reading the query content.
    # Continue reading until .toread reaches zero.
    set got [read $chan [dict get $W .toread]]
    dict append W CONTENT $got
    dict set W .toread [expr {[dict get $W .toread]-[string length $got]}]
    if {[dict get $W .toread]<=0} {
      # Handle the request as soon as all the query content is received
      set wapp $W
      wappInt-handle-request $chan 0
    }
  }
}

# Decode the HTTP request header.
#
# This routine is always running inside of a [catch], so if
# any problems arise, simply raise an error.
#
proc wappInt-parse-header {chan} {
  upvar #0 wappInt-$chan W
  set hdr [split [dict get $W .header] \n]
  if {$hdr==""} {return 1}
  set req [lindex $hdr 0]
  dict set W REQUEST_METHOD [set method [lindex $req 0]]
  if {[lsearch {GET HEAD POST} $method]<0} {
    error "unsupported request method: \"[dict get $W REQUEST_METHOD]\""
  }
  set uri [lindex $req 1]
  set split_uri [split $uri ?]
  set uri0 [lindex $split_uri 0]
  if {![regexp {^/[-.a-z0-9_/]*$} $uri0]} {
    error "invalid request uri: \"$uri0\""
  }
  dict set W REQUEST_URI $uri0
  dict set W PATH_INFO $uri0
  set uri1 [lindex $split_uri 1]
  dict set W QUERY_STRING $uri1
  set n [llength $hdr]
  for {set i 1} {$i<$n} {incr i} {
    set x [lindex $hdr $i]
    if {![regexp {^(.+): +(.*)$} $x all name value]} {
      error "invalid header line: \"$x\""
    }
    set name [string toupper $name]
    switch -- $name {
      REFERER {set name HTTP_REFERER}
      USER-AGENT {set name HTTP_USER_AGENT}
      CONTENT-LENGTH {set name CONTENT_LENGTH}
      CONTENT-TYPE {set name CONTENT_TYPE}
      HOST {set name HTTP_HOST}
      COOKIE {set name HTTP_COOKIE}
      ACCEPT-ENCODING {set name HTTP_ACCEPT_ENCODING}
      default {set name .hdr:$name}
    }
    dict set W $name $value
  }
  return 0
}

# Decode the QUERY_STRING parameters from a GET request or the
# application/x-www-form-urlencoded CONTENT from a POST request.
#
# This routine sets the ".qp" element of the ::wapp dict as a signal
# that query parameters have already been decoded.
#
proc wappInt-decode-query-params {} {
  global wapp
  dict set wapp .qp 1
  if {[dict exists $wapp QUERY_STRING]} {
    foreach qterm [split [dict get $wapp QUERY_STRING] &] {
      set qsplit [split $qterm =]
      set nm [lindex $qsplit 0]
      if {[regexp {^[a-z][a-z0-9]*$} $nm]} {
        dict set wapp $nm [wappInt-decode-url [lindex $qsplit 1]]
      }
    }
  }
  if {[dict exists $wapp CONTENT_TYPE] && [dict exists $wapp CONTENT]} {
    set ctype [dict get $wapp CONTENT_TYPE]
    if {$ctype=="application/x-www-form-urlencoded"} {
      foreach qterm [split [string trim [dict get $wapp CONTENT]] &] {
        set qsplit [split $qterm =]
        set nm [lindex $qsplit 0]
        if {[regexp {^[a-z][-a-z0-9_]*$} $nm]} {
          dict set wapp $nm [wappInt-decode-url [lindex $qsplit 1]]
        }
      }
    } elseif {[string match multipart/form-data* $ctype]} {
      regexp {^(.*?)\r\n(.*)$} [dict get $wapp CONTENT] all divider body
      set ndiv [string length $divider]
      while {[string length $body]} {
        set idx [string first $divider $body]
        set unit [string range $body 0 [expr {$idx-3}]]
        set body [string range $body [expr {$idx+$ndiv+2}] end]
        if {[regexp {^Content-Disposition: form-data; (.*?)\r\n\r\n(.*)$} \
             $unit unit hdr content] &&
            [regexp {name="(.*)"; filename="(.*)"\r\nContent-Type: (.*?)$}\
              $hdr hr name filename mimetype]} {
          dict set wapp $name.filename \
            [string map [list \\\" \" \\\\ \\] $filename]
          dict set wapp $name.mimetype $mimetype
          dict set wapp $name.content $content
        }
      }
    }
  }
}

# Invoke application-supplied methods to generate a reply to
# a single HTTP request.
#
# This routine always runs within [catch], so handle exceptions by
# invoking [error].
#
proc wappInt-handle-request {chan useCgi} {
  global wapp
  dict set wapp .reply {}
  dict set wapp .mimetype {text/html; charset=utf-8}
  dict set wapp .reply-code {200 Ok}
  dict set wapp .csp {default-src 'self'}

  # Set up additional CGI environment values
  #
  if {![dict exists $wapp HTTP_HOST]} {
    dict set wapp BASE_URL {}
  } elseif {[dict exists $wapp HTTPS]} {
    dict set wapp BASE_URL https://[dict get $wapp HTTP_HOST]
  } else {
    dict set wapp BASE_URL http://[dict get $wapp HTTP_HOST]
  }
  if {![dict exists $wapp REQUEST_URI]} {
    dict set wapp REQUEST_URI /
  } elseif {[regsub {\?.*} [dict get $wapp REQUEST_URI] {} newR]} {
    # Some servers (ex: nginx) append the query parameters to REQUEST_URI.
    # These need to be stripped off
    dict set wapp REQUEST_URI $newR
  }
  if {[dict exists $wapp SCRIPT_NAME]} {
    dict append wapp BASE_URL [dict get $wapp SCRIPT_NAME]
  } else {
    dict set wapp SCRIPT_NAME {}
  }
  if {![dict exists $wapp PATH_INFO]} {
    # If PATH_INFO is missing (ex: nginx) the construct it
    set URI [dict get $wapp REQUEST_URI]
    set skip [string length [dict get $wapp SCRIPT_NAME]]
    dict set wapp PATH_INFO [string range $URI $skip end]
  }
  if {[regexp {^/([^/]+)(.*)$} [dict get $wapp PATH_INFO] all head tail]} {
    dict set wapp PATH_HEAD $head
    dict set wapp PATH_TAIL [string trimleft $tail /]
  } else {
    dict set wapp PATH_INFO {}
    dict set wapp PATH_HEAD {}
    dict set wapp PATH_TAIL {}
  }
  dict set wapp SELF_URL [dict get $wapp BASE_URL]/[dict get $wapp PATH_HEAD]

  # Parse query parameters from the query string, the cookies, and
  # POST data
  #
  if {[dict exists $wapp HTTP_COOKIE]} {
    foreach qterm [split [dict get $wapp HTTP_COOKIE] {;}] {
      set qsplit [split [string trim $qterm] =]
      set nm [lindex $qsplit 0]
      if {[regexp {^[a-z][-a-z0-9_]*$} $nm]} {
        dict set wapp $nm [wappInt-decode-url [lindex $qsplit 1]]
      }
    }
  }
  set same_origin 0
  if {[dict exists $wapp HTTP_REFERER]} {
    set referer [dict get $wapp HTTP_REFERER]
    set base [dict get $wapp BASE_URL]
    if {$referer==$base || [string match $base/* $referer]} {
      set same_origin 1
    }
  }
  dict set wapp SAME_ORIGIN $same_origin
  if {$same_origin} {
    wappInt-decode-query-params
  }

  # Invoke the application-defined handler procedure for this page
  # request.  If an error occurs while running that procedure, generate
  # an HTTP reply that contains the error message.
  #
  wapp-before-dispatch-hook
  wappInt-trace
  set mname [dict get $wapp PATH_HEAD]
  if {[catch {
    if {$mname!="" && [llength [info proc wapp-page-$mname]]>0} {
      wapp-page-$mname
    } else {
      wapp-default
    }
  } msg]} {
    if {[wapp-param WAPP_MODE]=="local" || [wapp-param WAPP_MODE]=="server"} {
      puts "ERROR: $::errorInfo"
    }
    wapp-reset
    wapp-reply-code "500 Internal Server Error"
    wapp-mimetype text/html
    wapp-trim {
      <h1>Wapp Application Error</h1>
      <pre>%html($::errorInfo)</pre>
    }
    dict unset wapp .new-cookies
  }

  # Transmit the HTTP reply
  #
  if {$chan=="stdout"} {
    puts $chan "Status: [dict get $wapp .reply-code]\r"
  } else {
    puts $chan "HTTP/1.1 [dict get $wapp .reply-code]\r"
    puts $chan "Server: wapp\r"
    puts $chan "Connection: close\r"
  }
  if {[dict exists $wapp .reply-extra]} {
    foreach {name value} [dict get $wapp .reply-extra] {
      puts $chan "$name: $value\r"
    }
  }
  if {[dict exists $wapp .csp]} {
    puts $chan "Content-Security-Policy: [dict get $wapp .csp]\r"
  }
  set mimetype [dict get $wapp .mimetype]
  puts $chan "Content-Type: $mimetype\r"
  if {[dict exists $wapp .new-cookies]} {
    foreach {nm val} [dict get $wapp .new-cookies] {
      if {[regexp {^[a-z][-a-z0-9_]*$} $nm]} {
        if {$val==""} {
          puts $chan "Set-Cookie: $nm=; HttpOnly; Path=/; Max-Age=1\r"
        } else {
          set val [wappInt-enc-url $val]
          puts $chan "Set-Cookie: $nm=$val; HttpOnly; Path=/\r"
        }
      }
    }
  }
  if {[string match text/* $mimetype]} {
    set reply [encoding convertto utf-8 [dict get $wapp .reply]]
    if {[regexp {\ygzip\y} [wapp-param HTTP_ACCEPT_ENCODING]]} {
      catch {
        set x [zlib gzip $reply]
        set reply $x
        puts $chan "Content-Encoding: gzip\r"
      }
    }
  } else {
    set reply [dict get $wapp .reply]
  }
  puts $chan "Content-Length: [string length $reply]\r"
  puts $chan \r
  puts $chan $reply
  flush $chan
  wappInt-close-channel $chan
}

# This routine runs just prior to request-handler dispatch.  The
# default implementation is a no-op, but applications can override
# to do additional transformations or checks.
#
proc wapp-before-dispatch-hook {} {return}

# Process a single CGI request
#
proc wappInt-handle-cgi-request {} {
  global wapp env
  foreach key {
    CONTENT_LENGTH
    CONTENT_TYPE
    DOCUMENT_ROOT
    HTTP_ACCEPT_ENCODING
    HTTP_COOKIE
    HTTP_HOST
    HTTP_REFERER
    HTTP_USER_AGENT
    HTTPS
    PATH_INFO
    QUERY_STRING
    REMOTE_ADDR
    REQUEST_METHOD
    REQUEST_URI
    REMOTE_USER
    SCRIPT_FILENAME
    SCRIPT_NAME
    SERVER_NAME
    SERVER_PORT
    SERVER_PROTOCOL
  } {
    if {[info exists env($key)]} {
      dict set wapp $key $env($key)
    }
  }
  set len 0
  if {[dict exists $wapp CONTENT_LENGTH]} {
    set len [dict get $wapp CONTENT_LENGTH]
  }
  if {$len>0} {
    fconfigure stdin -translation binary
    dict set wapp CONTENT [read stdin $len]
  }
  dict set wapp WAPP_MODE cgi
  fconfigure stdout -translation binary
  wappInt-handle-request stdout 1
}

# Process new text received on an inbound SCGI request
#
proc wappInt-scgi-readable {chan} {
  if {[catch [list wappInt-scgi-readable-unsafe $chan] msg]} {
    puts stderr "$msg\n$::errorInfo"
    wappInt-close-channel $chan
  }
}
proc wappInt-scgi-readable-unsafe {chan} {
  upvar #0 wappInt-$chan W wapp wapp
  if {![dict exists $W .toread]} {
    # If the .toread key is not set, that means we are still reading
    # the header.
    #
    # An SGI header is short.  This implementation assumes the entire
    # header is available all at once.
    #
    set req [read $chan 15]
    set n [string length $req]
    scan $req %d:%s len hdr
    incr len [string length "$len:,"]
    append hdr [read $chan [expr {$len-15}]]
    foreach {nm val} [split $hdr \000] {
      if {$nm==","} break
      dict set W $nm $val
    }
    set len 0
    if {[dict exists $W CONTENT_LENGTH]} {
      set len [dict get $W CONTENT_LENGTH]
    }
    if {$len>0} {
      # Still need to read the query content
      dict set W .toread $len
    } else {
      # There is no query content, so handle the request immediately
      set wapp $W
      wappInt-handle-request $chan 0
    }
  } else {
    # If .toread is set, that means we are reading the query content.
    # Continue reading until .toread reaches zero.
    set got [read $chan [dict get $W .toread]]
    dict append W CONTENT $got
    dict set W .toread [expr {[dict get $W .toread]-[string length $got]}]
    if {[dict get $W .toread]<=0} {
      # Handle the request as soon as all the query content is received
      set wapp $W
      wappInt-handle-request $chan 0
    }
  }
}

# Start up the wapp framework.  Parameters are a list passed as the
# single argument.
#
#    -server $PORT         Listen for HTTP requests on this TCP port $PORT
#
#    -local $PORT          Listen for HTTP requests on 127.0.0.1:$PORT
#
#    -scgi $PORT           Listen for SCGI requests on TCP port $PORT
#
#    -cgi                  Handle a single CGI request
#
# With no arguments, the behavior is called "auto".  In "auto" mode,
# if the GATEWAY_INTERFACE environment variable indicates CGI, then run
# as CGI.  Otherwise, start an HTTP server bound to the loopback address
# only, on an arbitrary TCP port, and automatically launch a web browser
# on that TCP port.
#
# Additional options:
#
#    -trace               "puts" each request URL as it is handled, for
#                         debugging
#
#    -lint                Run wapp-safety-check on the application instead
#                         of running the application itself
#
#    -Dvar=value          Set TCL global variable "var" to "value"
#
#
proc wapp-start {arglist} {
  global env
  set mode auto
  set port 0
  set n [llength $arglist]
  for {set i 0} {$i<$n} {incr i} {
    set term [lindex $arglist $i]
    if {[string match --* $term]} {set term [string range $term 1 end]}
    switch -glob -- $term {
      -server {
        incr i;
        set mode "server"
        set port [lindex $arglist $i]
      }
      -local {
        incr i;
        set mode "local"
        set port [lindex $arglist $i]
      }
      -scgi {
        incr i;
        set mode "scgi"
        set port [lindex $arglist $i]
      }
      -cgi {
        set mode "cgi"
      }
      -trace {
        proc wappInt-trace {} {
          set q [wapp-param QUERY_STRING]
          set uri [wapp-param BASE_URL][wapp-param PATH_INFO]
          if {$q!=""} {append uri ?$q}
          puts $uri
        }
      }
      -lint {
        set res [wapp-safety-check]
        if {$res!=""} {
          puts "Potential problems in this code:"
          puts $res
          exit 1
        } else {
          exit
        }
      }
      -D*=* {
        if {[regexp {^.D([^=]+)=(.*)$} $term all var val]} {
          set ::$var $val
        }
      }
      default {
        error "unknown option: $term"
      }
    }
  }
  if {($mode=="auto"
       && [info exists env(GATEWAY_INTERFACE)]
       && [string match CGI/1.* $env(GATEWAY_INTERFACE)])
    || $mode=="cgi"
  } {
    wappInt-handle-cgi-request
    return
  }
  if {$mode=="scgi"} {
    wappInt-start-listener $port scgi
  } elseif {$mode=="server"} {
    wappInt-start-listener $port server
  } else {
    wappInt-start-listener $port local
  }
  vwait ::forever
}

# Call this version 1.0
package provide wapp 1.0

#### End of wapp.tcl

# Generate all header content for the output document
#
proc search_header {} {
  wapp-trim {
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html><head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<link href="sqlite.css" rel="stylesheet">
<title>Search SQLite Documentation</title>
<!-- path= -->
</head>
<body>
<div class=nosearch>
<a href="index.html">
<img class="logo" src="images/sqlite370_banner.gif" alt="SQLite" border="0">
</a>
<div><!-- IE hack to prevent disappearing logo --></div>
<div class="tagline desktoponly">
Small. Fast. Reliable.<br>Choose any three.
</div>
<div class="menu mainmenu">
<ul>
<li><a href="index.html">Home</a>
<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a>
<li class='wideonly'><a href='about.html'>About</a>
<li class='desktoponly'><a href="docs.html">Documentation</a>
<li class='desktoponly'><a href="download.html">Download</a>
<li class='wideonly'><a href='copyright.html'>License</a>
<li class='desktoponly'><a href="support.html">Support</a>
<li class='desktoponly'><a href="prosupport.html">Purchase</a>
<li class='search' id='search_menubutton'>
<a href="javascript:void(0)" onclick='toggle_search()'>Search</a>
</ul>
</div>
<div class="menu submenu" id="submenu">
<ul>
<li><a href='about.html'>About</a>
<li><a href='docs.html'>Documentation</a>
<li><a href='download.html'>Download</a>
<li><a href='support.html'>Support</a>
<li><a href='prosupport.html'>Purchase</a>
</ul>
</div>
<div class="searchmenu" id="searchmenu">
<form method="GET" action="search">
<select name="s" id="searchtype">
<option value="d">Search Documentation</option>
<option value="c">Search Changelog</option>
</select>
<input type="text" name="q" id="searchbox" value="">
<input type="submit" value="Go">
</form>
</div>
</div>
<script>
function toggle_div(nm) {
var w = document.getElementById(nm);
if( w.style.display=="block" ){
w.style.display = "none";
}else{
w.style.display = "block";
}
}
function toggle_search() {
var w = document.getElementById("searchmenu");
if( w.style.display=="block" ){
w.style.display = "none";
} else {
w.style.display = "block";
setTimeout(function(){
document.getElementById("searchbox").focus()
}, 30);
}
}
function div_off(nm){document.getElementById(nm).style.display="none";}
window.onbeforeunload = function(e){div_off("submenu");}
/* Disable the Search feature if we are not operating from CGI, since */
/* Search is accomplished using CGI and will not work without it. */
if( !location.origin.match || !location.origin.match(/http/) ){
document.getElementById("search_menubutton").style.display = "none";
}
/* Used by the Hide/Show button beside syntax diagrams, to toggle the */
function hideorshow(btn,obj){
var x = document.getElementById(obj);
var b = document.getElementById(btn);
if( x.style.display!='none' ){
x.style.display = 'none';
b.innerHTML='show';
}else{
x.style.display = '';
b.innerHTML='hide';
}
return false;
}
</script>
</div>
  }
}

#-------------------------------------------------------------------------
# Add an entry to the log database for the current query. Which 
# returns $nRes results.
#
proc search_add_log_entry {nRes} {
  if {[wapp-param-exists donotlog]} return
  sqlite3 db2 [file dir [wapp-param SCRIPT_FILENAME]]/search.d/searchlog.db
  db2 timeout 10000
  set ip [wapp-param REMOTE_ADDR]
  set query [wapp-param q]
  db2 eval {
    PRAGMA synchronous=OFF;
    PRAGMA journal_mode=OFF;
    BEGIN;
      CREATE TABLE IF NOT EXISTS log(
        ip,                  -- IP query was made from
        query,               -- Fts5 query string
        nres,                -- Number of results
        timestamp DEFAULT CURRENT_TIMESTAMP
      );
      INSERT INTO log(ip, query, nres) VALUES($ip, $query, $nRes);
    COMMIT;
  }
  db2 close
}

#-------------------------------------------------------------------------
# This command is similar to the builtin Tcl [time] command, except that
# it only ever runs the supplied script once. Also, instead of returning
# a string like "xxx microseconds per iteration", it returns "x.yy ms" or
# "x.yy s", depending on the magnitude of the time spent running the 
# command. For example:
#
#   % ttime {after 1500}
#   1.50 s
#   % ttime {after 45}
#   45.02 ms
#
proc ttime {script} {
  set t [lindex [time [list uplevel $script]] 0]
  if {$t>1000000} { return [format "%.2f s" [expr {$t/1000000.0}]] }
  return [format "%.2f ms" [expr {$t/1000.0}]]
}

#-----------------------------------------------------------------------
# Do a search of the change log
#
proc searchchanges {} {
  set q [wapp-param q]
  if {$q==""} {return {}}
  set open {<span style="background-color:#d9f2e6">}
  set close {</span>}
  set query {
    SELECT url, version, idx, highlight(change, 3, $open, $close) AS text 
    FROM change($q) ORDER BY rowid ASC
  }
  wapp-trim {
    <p>Change log entries mentioning: <b>%html($q)</b>
    <table border=0>
  }
  set s2 "style=\"margin-top:0\""
  set s1 "style=\"font-size:larger; text-align:left\" class=nounderline"
  set prev ""
  db eval $query {
    if {$prev!=$version} {
      wapp-trim {
        <tr> <td %unsafe($s1) valign=top> <a href='%url($url)'>%html($version)</a>
        <td> <ul %unsafe($s2)>
      }
      set prev $version
    }
    wapp-subst {<li value=%html($idx)> (%html($idx)) %unsafe($text)\n}
  }
  wapp-trim {
    </table>
    <center><p>You can also see the <a href=changes.html>entire
    changelog as a single page</a> if you wish.</center>
  }
}

#-----------------------------------------------------------------------
# Do a search over all documentation other than the change log
#
proc searchresults {} {
  set q [wapp-param q]
  if {$q==""} {return ""}

  # Count the '"' characters in $::A(q). If there is an odd number of
  # occurences, add a " to the end of the query so that fts5 can parse
  # it without error.
  if {[regexp -all \x22 $q] % 2} { append q \x22 }

  # Set iStart to the index of the first result to display. Results are
  # indexed starting at zero from most to least relevant.
  #
  set iStart 0
  catch {set iStart [expr {[wapp-param i 0]*10}]}

  # Grab a list of rowid results.
  #
  set sql {
    SELECT rowid FROM page WHERE page MATCH $q
    ORDER BY srank(page) DESC,
    rank * COALESCE(
      (SELECT percent FROM weight WHERE id=page.rowid), 100
    );
  }
  if {[catch { set lRowid [db eval $sql] }]} {
    set x ""
    foreach word [split $q " "] {
      append x " \"[string map [list "\"" "\"\""] $word]\""
    }
    set q [string trim $x]
    set lRowid [db eval $sql]
  }

  set lRes [list]
  foreach rowid $lRowid {
    if {$rowid > 1000} {
      set parent [expr $rowid / 1000]
      lappend subsections($parent) $rowid
    } else {
      lappend lRes $rowid
    }
  }

  set nRes [llength $lRes]
  set lRes [lrange $lRes $iStart [expr $iStart+9]]

  # Add an entry to the log database.
  #
  search_add_log_entry $nRes

  # If there are no results, return a message to that effect.
  #
  if {[llength $lRes] == 0} {
    wapp-subst {<p>No Results for: <b>%html($q)</b>\n}
  }
  
  # HTML markup used to highlight keywords within FTS5 generated snippets.
  #
  set open {<span style="background-color:#d9f2e6">}
  set close {</span>}
  set ellipsis {<b>&nbsp;...&nbsp;</b>}

  # Grab the required data
  #
  db eval [string map [list %LIST% [join $lRowid ,]] {
    SELECT 
      rowid AS parentid, 
      snippet(page, 0, $open, $close, $ellipsis, 6)  AS s_apis,
      snippet(page, 2, $open, $close, '', 40)        AS s_title1,
      snippet(page, 3, $open, $close, $ellipsis, 40) AS s_title2,
      snippet(page, 4, $open, $close, $ellipsis, 40) AS s_content,
      url, rank
    FROM page($q)
    WHERE rowid IN (%LIST%)
  }] X {
    foreach k [array names X] { set data($X(parentid),$k) [set X($k)] }
  }

  set i1 [expr {$iStart+1}]
  set i2 [expr {($nRes < $iStart+10) ? $nRes : $iStart+10}]
  wapp-trim {
    <table border=0>
    <p>Search results %html($i1)..%html($i2) of %html($nRes) for: <b>%html($q)</b>
  }

  foreach rowid $lRes {

    foreach a {parentid s_apis s_title1 s_content url rank} {
      set $a $data($rowid,$a)
    }

    if {[info exists subsections($parentid)]} {
      set childid [lindex $subsections($parentid) 0]
      set link $data($childid,url)
      set hdr $data($childid,s_title2)

      if {$hdr==""} {
        set s_content ""
      } else {
        set s_content [subst {
          <b><a style=color:#044a64 href=$link>$hdr</a></b>
        }]
      }

      append s_content " $data($childid,s_content)"
    }

    wapp-trim {<tr>
      <td valign=top style="line-height:150%">
        <div style="white-space:wrap;font-size:larger" class=nounderline>
          <a href="%url($url)">%unsafe($s_title1)</a> 
          <div style="float:right;font-size:smaller;color:#BBB">(%url($url))</div>
        </div>
          <div style="margin-left: 10ex; font:larger monospace">%unsafe($s_apis)</div>
        <div style="margin-left: 4ex; margin-bottom:1.5em">
           %unsafe($s_content)
        </div>
      </td>
    }
  }
  wapp-subst {</table>\n}


  # If the query returned more than 10 results, add up to 10 links to 
  # each set of 10 results (first link to results 1-10, second to 11-20, 
  # third to 21-30, as required).
  #
  if {$nRes>10} {
    set s(0) {border:solid #044a64 1px;padding:1ex;margin:1ex;line-height:300%;}
    set s(1) "$s(0);background:#044a64;color:white"
    wapp-subst {<center><p>\n}
    for {set i 0} {$i < 10 && ($i*10)<$nRes} {incr i} {
      set style $s([expr {($iStart/10)==$i}])
      wapp-trim {
        <a style="%html($style)"
           href="search?q=%qp($q)&i=%qp($i)">%html([expr $i+1])</a>
      }
    }
    wapp-subst {</center>\n}
  }
}

# This is the main entry point into the search result page generator
#
proc wapp-default {} {
  wapp-content-security-policy {default-src 'self' 'unsafe-inline'}
  wapp-allow-xorigin-params
  if {[wapp-param-exists env]} {
    search_header
    wapp-trim {
      <h1>Environment Dump For Debugging</h1>
      <pre>%html([wapp-debug-env])</pre>
    }
    return
  }

  # When running using the built-in webserver in Wapp (in other words,
  # when not running as CGI) any filename that contains a "." loads
  # directly from the filesystem.
  if {[wapp-param WAPP_MODE]!="cgi"
   && [string match *.* [wapp-param PATH_INFO]]
  } {
    set altfile [file dir [wapp-param SCRIPT_FILENAME]][wapp-param PATH_INFO]
    set fd [open $altfile rb]
    fconfigure $fd -translation binary
    wapp-unsafe [read $fd]
    close $fd
    switch -glob -- $altfile {
      *.html {
        wapp-mimetype text/html
      }
      *.css {
        wapp-mimetype text/css
      }
      *.gif {
        wapp-mimetype image/gif
      }
    }
    return
  }

  search_header
  sqlite3 db [file dir [wapp-param SCRIPT_FILENAME]]/search.d/search.db
  set searchType [wapp-param s d]
  if {$searchType=="c"} {
    set cmd searchchanges
  } else {
    set cmd searchresults
  }
  db transaction {
    set t [ttime {$cmd}]
  }
  wapp-trim {
    <center>
    <p>Page generated by <a href='fts5.html'>FTS5</a> in about %html($t).
    </center>
    <script>
      window.addEventListener('load', function() {
        var w = document.getElementById("searchmenu");
        w.style.display = "block";
        w = document.getElementById("searchtype");
        w.value = "%string($searchType)"
        setTimeout(function(){
          var s = document.getElementById("searchbox");
          s.value = "%string([wapp-param q])"
          s.focus();
          s.select();
        }, 30);
      });
    </script>
  }
}
wapp-start $argv
