#!/usr/bin/ruby

OUTDIR = "/var/www/html/rrd"
RRD = "#{OUTDIR}/wis.rrd"
THR_FILE = "#{OUTDIR}/wis-thr.txt"

START = "-604800"  # 7日
END_T = "now"

UPPER_LIMIT = 500.0
MARGIN = 1.1

$VERBOSE=true if STDERR.tty?

# ----------------------------
# 閾値読み込み
# ----------------------------
t_wnm, t_top, t_brw = File.read(THR_FILE).split.map(&:to_f)

# ----------------------------
# RRD fetch
# ----------------------------
raw = `rrdtool fetch #{RRD} AVERAGE --start #{START} --end #{END_T}`

data = []

raw.each_line do |line|
  next unless line =~ /^\d+:/

  ts, wnm, top, brw = line.split
  next if wnm == "nan"

  data << [ts.to_i, wnm.to_f, top.to_f, brw.to_f]
end

# ----------------------------
# kaku kenti script ga izyou ti to suru atai
# ----------------------------
def is_syserr val
  val > 500.0
end

# ----------------------------
# 単発スパイク検出
# ----------------------------
def detect_spikes(series, threshold)
  spikes = []

  (1...(series.size - 1)).each do |i|
    prev = series[i - 1]
    curr = series[i]
    nxt  = series[i + 1]

    if is_syserr(curr)
      warn "syserr #{curr} excluded from spike-detecting"
      next
    end

    if curr > threshold && prev <= threshold && nxt <= threshold
      spikes << curr
    end
  end

  spikes
end

wnm_series = data.map { |r| r[1] }
top_series = data.map { |r| r[2] }
brw_series = data.map { |r| r[3] }

wnm_spikes = detect_spikes(wnm_series, t_wnm)
top_spikes = detect_spikes(top_series, t_top)
brw_spikes = detect_spikes(brw_series, t_brw)

# ----------------------------
# 新しい閾値計算
# ----------------------------
def calc_new_threshold(spikes, current)
  return current if spikes.empty?

  max = spikes.max
  new_val = max * MARGIN

  # 上限適用
  new_val = UPPER_LIMIT if new_val > UPPER_LIMIT

  new_val
end

new_wnm = calc_new_threshold(wnm_spikes, t_wnm)
new_top = calc_new_threshold(top_spikes, t_top)
new_brw = calc_new_threshold(brw_spikes, t_brw)

updated =
  (new_wnm != t_wnm) ||
  (new_top != t_top) ||
  (new_brw != t_brw)

fmsg=''
# ----------------------------
# 書き込み
# ----------------------------
begin
  if updated then
    File.write(
      THR_FILE,
      format("%.1f %.1f %.1f\n", new_wnm, new_top, new_brw)
    )
  end
rescue Errno::EACCES => e
  fmsg=e.to_s
end

# ----------------------------
# ログ出力
# ----------------------------

subject =
  if !fmsg.empty?
    "[Error]WIS Monitor"
  elsif updated
    "[Adjusted]WIS Monitor"
  else
    "[NoChange]WIS Monitor"
  end

open("|/usr/sbin/sendmail -t","wt"){|mail|
  mail.puts "Subject: #{subject}\r"
  mail.puts "To: news\r"
  mail.puts "\r"
  if updated
    mail.puts "Thresholds were updated."
  else
    mail.puts "No threshold update was required."
    mail.puts "No single-point spikes exceeding the current thresholds were found in the past 7 days."
  end
  mail.puts ""
  mail.puts "---- Threshold Update ----"
  mail.puts "WNM: #{t_wnm} -> #{new_wnm} (spikes=#{wnm_spikes.size})"
  mail.puts "TOP: #{t_top} -> #{new_top} (spikes=#{top_spikes.size})"
  mail.puts "BRW: #{t_brw} -> #{new_brw} (spikes=#{brw_spikes.size})"
  mail.puts "WNM spikes: count=#{wnm_spikes.size} max=#{wnm_spikes.max || '-'}"
  mail.puts "TOP spikes: count=#{top_spikes.size} max=#{top_spikes.max || '-'}"
  mail.puts "BRW spikes: count=#{brw_spikes.size} max=#{brw_spikes.max || '-'}"
  mail.puts "Upper limit applied: #{UPPER_LIMIT}"
  unless fmsg.empty?
    mail.puts ""
    mail.puts fmsg
  end
}