# sq - structured query
# christian neukirchen, mit-licensed.
# 06apr2008
#
# usage:
#
# sq query datafiles...
#
# entries, seperated by two newlines:
# 
# tag1 tag2 "tag3"
# field=value "field2"=value field3="value"
# field: value on rest of line
# field: "multi line string
# without any quotes in it"
# 
# implemented query language:
# 
# x      has x
# x=y    has x with value y
# x>y  x<y  x>=y  x<=y  comparison
# x~rx  x~~rx           matches regexp case-insensitive, case-sensitive
# q q    conjunction
# 
# <x     sort by x
# >x     reverse sort by x
# ~rx ~~rx   entry matches rx case-insensitive, case-sensitive anywhere

query = ARGV.shift  or abort File.read($0)[/\A.*?\n\n/m].chop

set = []
while hunk = gets("")
  hunk.rstrip!
  data = {"" => hunk}
  hunk = hunk.gsub(/".*?"/m) { $&.tr("\n", ' ') }
  hunk.each { |line|
    if line =~ /^([\w-]+):\s+("(.*)"|(.*))/
      data[$1.downcase] = $2 || $3
    else
      line.scan(/([\w-]+|"(.*?)")(\s*=\s*([\w+-]+|"(.*?)"))?/) {
        data[$2 || $1] = $5 || $4 || true
      }
    end
  }
  set << data
end

def dont_leak
Array.send(:include, Comparable)
String.send(:define_method, "~~") { |s| self =~ Regexp.new(s) }
String.send(:define_method, "~")  { |s| self =~ Regexp.new(s, "i") }
String.send(:define_method, "=")  { |s| self == s }
String.send(:define_method, "sm") { split(/(\d+)/).map { |e| [e.to_i, e] } }
end; dont_leak

query.scan(/([\w-]+|"(.*?)"|)((=|<|>|<=|>=|~~|~)([\w+-]+|"(.*?)"))?/) {
  if $1 == "" && ($4 == "<" || $4 == ">")
    set = set.sort_by { |f| f[$6 || $5].sm }  rescue set
    set.reverse!  if $4 == ">"
  else
    set = set.find_all { |f|
      f.include?($2 || $1) &&
        case $4
          when "<", ">", "<=", ">="; f[$2 || $1].sm.send($4, ($6 || $5).sm)
          when "=", "~", "~~";       f[$2 || $1].   send($4,  $6 || $5)
          when nil;                  true
          else                       false
        end
    }
  end
}

puts set.map { |f| f[""] }.join("\n\n")  unless set.empty?