#!/usr/bin/env ruby
# notyet [-ace] [-f FILE] [FILTERS...] - a todo tracker
#
# notyet is in the public domain.
# To the extent possible under law, Leah Neukirchen <leah@vuxu.org>
# has waived all copyright and related or neighboring rights to this work.
# http://creativecommons.org/publicdomain/zero/1.0/

require 'optionparser'
require 'date'
require 'time'

TODAY = Date.today
NOW = Time.now
DEFER_DAYS = 14

class Entry < Struct.new(:depth, :state, :desc, :file, :line, :children)
  def reindent(change)
    self.depth += change
    children.each { |c| c.reindent change }
    self
  end

  def dump
    unless $show_all
      return  if "xX".index(state)
      return  if count("xX") == count
    end

    if depth < 0
      puts "#{desc.strip} [#{stat}]".lstrip  unless $edit
    else
      stat = children.empty? ? "" : " [#{self.stat}]"
      print "#{file}:#{line}\t"  if $edit && depth >= 0
      print "#{" " * depth}#{state} #{desc}#{stat}\n"  if depth >= 0
    end

    children.each { |c| c.dump }
  end

  def stat
    children.each { |c| c.stat }
    @stat ||= "#{count("xX")}/#{count("-xX")}"
  end

  def count(s=nil)
    if children.empty? && (s.nil? || s.index(state))
      return 1
    else
      children.map { |c| c.count(s) }.sum
    end
  end

  def sort
    children.each { |c| c.sort }
    children.sort_by! { |c| [c.state, c.dateorder, c.desc] }
  end

  def dateorder
    if desc =~ /^(?:\(.*?\)\s*)?\[(\d\d\d\d-\d\d-\d\d)( \d\d:\d\d)?\]([+!~-]?)/
      d = Time.parse("#{$1}#{$2}")
      case $3
      when "+", ""  # todo (default) = earliest first
        d - NOW
      when "-"      # reminder = sort by difference to now
        (d - NOW).abs
      when "!"      # deadline, drop after the time
        if NOW < d
          d - NOW
        else
          Float::INFINITY
        end
      when "~"        # defer, sink and raise periodically
        if NOW < d
          d - NOW
        else
          # sawtooth function
          (DEFER_DAYS -
           (((TODAY - d.to_date) % (2*DEFER_DAYS)) - DEFER_DAYS).abs) * 24*60*60
        end
      end
    else
      Float::INFINITY
    end
  end

  def propagate
    unless children.empty?
      children.each { |c| c.propagate }
      if children.all? { |c| "X".index(c.state) }
        self.state = "X"
      elsif children.all? { |c| "xX".index(c.state) }
        self.state = "x"
      elsif children.all? { |c| "?xX".index(c.state) }
        self.state = "?"
      end

      force(state)  if "?xX".index(state)

      if desc =~ /^(?:\(.*?\)\s*)?\[(\d\d\d\d-\d\d-\d\d)( \d\d:\d\d)?\]/
        diff = "%+d" % (Date.parse($1) - TODAY)
        self.desc = "[#{$1}#{$2}] {#{diff}}#{$'}"
      else
        soonest = children.map { |c|
          "-?".index(c.state) &&
            c.desc[/^(?:\(.*?\)\s*)?\[(\d\d\d\d-\d\d-\d\d)( \d\d:\d\d)?\]/, 1]
        }.compact.min
        if soonest
          diff = "%+d" % (Date.parse(soonest) - TODAY)
          self.desc = "[#{soonest}] {#{diff}} #{desc}"
        end
      end
    end
  end

  def force(state)
    self.state = state  unless "xX?*".index(self.state)
    children.each { |c| c.force(state) }
  end

  # remove two layers of parents
  def splat
    self.children = children.map { |c|
      c.splat

      if c.desc == "#splat"
        if c.children.empty?
          []
        else
          sub = c.children.map { |cc| cc.children }.flatten
          rel = sub.first.depth - c.depth
          sub.map { |cc| cc.reindent(-rel) }
        end
      else
        [c]
      end
    }.flatten(1)
  end

  def match1(word)
    desc =~ %r{(^|\W)#{Regexp.quote word.to_s}($|\W)}
  end

  def match(word)
    # need to match all non-@ words, and one of the mentioned @-words (if any)
    tags, words = word.partition { |w| w =~ /^@/ }
    (tags.empty? || tags.any? { |w| match1(w) }) && words.all? { |w| match1(w) }
  end

  def rmatch(word)
    match(word) || children.any? { |c| c.rmatch(word) }
  end

  def filter(word)
    if !match(word)
      children.reject! { |c| !c.rmatch(word) }
      children.each { |c| c.filter(word) }
    end
  end
end

def parse(io, filename=nil)
  todos = [Entry.new(-1, "/", "", "", 0, [])]

  filter = (io.stat.ftype != "file")

  while line = io.gets
    if filter && line =~ /^(.*):(\d+)\t/
      fname, lineno, line = $1, $2.to_i, $'
    else
      fname, lineno = filename, io.lineno
    end

    if line =~ /\A(?:\s*(?:#|\/\/)\s)?(\s*)([-xX?*])\s+(.*)/
      i, state, desc = $1.size, $2, $3
      while i <= todos.last.depth
        todos.pop
      end

      children = []

      if desc =~ /^#exec\s+(.+)/
        Dir.chdir(File.dirname(fname)) {
          begin
            IO.popen($1) { |f|
              sub = parse(f, $1)
              sub.reindent(i+2)
              children = sub.children
            }
          rescue SystemCallError => e
            children = [Entry.new(i+2, "?", "ERROR: #{e}", fname, lineno, [])]
          end
        }
        next  if children.empty?
      elsif desc =~ /^#include\s+(\S+)/
        n = File.expand_path($1, File.dirname(fname))
        begin
          File.open(n) { |f|
            sub = parse(f, $1)
            sub.reindent(i+2)
            children = sub.children
          }
        rescue SystemCallError => e
          children = [Entry.new(i+2, "?", "ERROR: #{e}", fname, lineno, [])]
        end
        next  if children.empty?
      elsif desc =~ /^#includeall\s+(\S+)/
        Dir.glob(File.expand_path($1, File.dirname(fname))) { |file|
          File.open(file) { |f|
            sub = parse(f, $1)
            sub.reindent(i+4)
            children << Entry.new(i+2, state, "#include #{file}", fname, lineno, sub.children)
          }
        }
        next  if children.empty?
      end
     
      e = Entry.new(i, state, desc, fname, lineno, children)
      todos.last.children << e
      todos << e
    end
  end

  todos.first
end

files = []
filter = []
$show_all = $edit = false
count_only = false

opt_parser = OptionParser.new { |opts|
  opts.banner = "Usage: notyet [-ace] [-f FILE] [FILTERS...]"
  opts.summary_width = 9
  opts.on("-a", "show all tasks (default: open tasks only)") { $show_all = true }
  opts.on("-c", "only show total count") { count_only = true }
  opts.on("-f FILE", "read tasks from FILE (default ~/.notyet)") { |f| files << f }
  opts.on("-e", "edit tasks in vim") { $edit = true }
}.parse! ARGV

files = [File.expand_path("~/.notyet")]  if files.empty?

t = nil
if files.size > 1
  t = Entry.new(-1, "/", "", "", 0, [])
end
files.each { |file|
  file = "/dev/stdin"  if file == "-"
  File.open(file) { |f|
    d = parse(f, file)
    if t
      d.state = "-"
      d.desc = file
      d.reindent(2)
      d.depth = 0
      t.children << d
    else
      t = d
    end
  }
}

t.splat
t.propagate
t.sort
t.stat
t.filter(ARGV)

if count_only
  puts "#{t.count("xX")}/#{t.count("-xX*")}"
  exit
end

if t.children.empty? && !ARGV.empty?
  exit 1
end

if $edit && STDOUT.tty?
  rd, wr = IO.pipe
  $stdout = wr
  Process.spawn('vim',
                '+nmap <buffer><CR> ^gF',
                '+nmap <buffer><TAB> <CR>',
                '+nnoremap <buffer>o ^gFo- |' \
                 'nnoremap <buffer>x ^gF^rx | nnoremap <buffer>X ^gF^rX |' \
                 'nnoremap <buffer>- ^gF^r- | nnoremap <buffer>? ^gF^r?',
                '+setl nomod noma nowrap conceallevel=3 concealcursor=nc',
                '+syn match Conceal /^.\{-}\t/ conceal',
                '+syn match Comment /\t\s*[xX].*/lc=1',
                '+hi Comment cterm=NONE ctermfg=darkgrey ctermbg=NONE guifg=#777777 guibg=NONE',
                '-',
                0 => rd)
  t.dump
  $stdout.close
  Process.wait
  exit $?.exitstatus
else
  t.dump
end