#!/usr/bin/env ruby

require 'sqlite3'
require 'syslog'

DB_FILE = "metrics.db"

facility= if STDERR.tty? then Syslog::LOG_USER else Syslog::LOG_NEWS end
Syslog.open('iwg_watch', Syslog::LOG_PID, facility)
db = SQLite3::Database.new(DB_FILE)

now_ts =
  db.get_first_value(
    "select max(ts) from metrics"
  )

abort("metrics table empty") unless now_ts

$nolog=true
def sys_info msg
  $nolog=false
  Syslog.info(msg)
  puts msg
end

class Time
  def show
    self.utc.strftime('%Y-%m-%dT%H:%M:%SZ')
  end
end

thresholds = db.execute(
  <<~SQL
    SELECT
      t.center_id,
      t.metric,
      t.low1,
      t.low3,
      t.low24,
      t.high1,
      t.high3,
      s.last_zero_time,
      s.last_nonzero_time
    FROM thresholds t
    LEFT JOIN last_state s
      USING(center_id, metric);
  SQL
)

thresholds.each do |row|

  center_id,
  metric,
  low1,
  low3,
  low24,
  high1,
  high3,
  last_zero_time,
  last_nonzero_time = row

  #
  # 最新24時間分取得
  #

  data =
    db.execute(
      <<~SQL, [center_id, metric, now_ts - 24 * 3600]
        select
          ts,
          value
        from metrics
        where center_id = ?
          and metric = ?
          and ts >= ?
        order by ts
      SQL
    )

  next if data.empty?

  values =
    data.map { |_, value| value.to_f }

  #
  # v1
  #

  next if values.size < 2

  prev_v1 = values[-2]
  curr_v1 = values[-1]

  #
  # v3
  #

  prev_v3 = nil
  curr_v3 = nil

  if values.size >= 3
    curr_v3 = values.last(3).sum
  end

  if values.size >= 4
    prev_v3 = values[-4, 3].sum
  end

  #
  # v24
  #

  curr_v24 = values.sum
  prev_v24 = values[0...-1].sum

  #
  # low1
  #

  if low1 > 0 then
    if prev_v1 >= low1 && curr_v1 < low1 then
      msg=
        "ALERT low1 "\
        "#{center_id}.#{metric} "\
        "current=#{curr_v1} threshold=#{low1}"
      if curr_v1==0 then
        if last_zero_time then
          age=((now_ts-last_zero_time)/86400.0).round(1)
          msg += " last_zero=#{Time.at(last_zero_time).show}"\
            " days_since_zero=#{age}"
        else
          msg += " last_zero=(null)"
        end
      end
      sys_info(msg)
    end
    if prev_v1 < low1 && curr_v1 >= low1 then
      msg=
        "RECOVER low1 "\
        "#{center_id}.#{metric} "\
        "current=#{curr_v1} threshold=#{low1}"
      if last_nonzero_time then
        age=((now_ts-last_nonzero_time)/86400.0).round(2)
        msg += " last_nonzero=#{Time.at(last_nonzero_time).show}"\
          " days_since_nonzero=#{age}"
      else
        msg += " last_nonzero=(null)"
      end
      sys_info(msg)
    end
  end

  #
  # high1
  #

  if prev_v1 <= high1 && curr_v1 > high1
    msg=
      "ALERT high1 "\
      "#{center_id}.#{metric} "\
      "current=#{curr_v1} threshold=#{high1.round(2)}"
    if high1==0.0 then
      if last_nonzero_time then
        age=((now_ts-last_nonzero_time)/86400.0).round(1)
        msg += " last_nonzero=#{Time.at(last_nonzero_time).show}"\
          " days_since_nonzero=#{age}"
      else
        msg += " last_nonzero=(null)"
      end
    end
    sys_info(msg)
  end

  #
  # low3
  #

  if prev_v3 && curr_v3
    if prev_v3 >= low3 && curr_v3 < low3
      msg=
        "ALERT low3 "\
        "#{center_id}.#{metric} "\
        "current=#{curr_v3} threshold=#{low3}"
      if curr_v3==0 then
        if last_zero_time then
          age=((now_ts-last_zero_time)/86400.0).round(1)
          msg += " last_zero=#{Time.at(last_zero_time).show}"\
            " days_since_zero=#{age}"
        else
          msg += " last_zero=(null)"
        end
      end
      sys_info(msg)
    end
  end

  #
  # high3
  #

  if prev_v3 && curr_v3
    if prev_v3 <= high3 && curr_v3 > high3
      msg=
        "ALERT high3 "\
        "#{center_id}.#{metric} "\
        "current=#{curr_v3} threshold=#{high3.round(2)}"
      if high3==0.0 then
        if last_nonzero_time then
          age=((now_ts-last_nonzero_time)/86400.0).round(1)
          msg += " last_nonzero=#{Time.at(last_nonzero_time).show}"\
            " days_since_nonzero=#{age}"
        else
          msg += " last_nonzero=(null)"
        end
      end
      sys_info(msg)
    end
  end

  #
  # low24
  #

  if low24 > 0
    if prev_v24 >= low24 && curr_v24 < low24
      msg=
        "ALERT low24 "\
        "#{center_id}.#{metric} "\
        "current=#{curr_v24} threshold=#{low24}"
      if curr_v24==0 then
        if last_zero_time then
          age=((now_ts-last_zero_time)/86400.0).round(1)
          msg += " last_zero=#{Time.at(last_zero_time).show}"\
            " days_since_zero=#{age}"
        else
          msg += " last_zero=(null)"
        end
      end
      sys_info(msg)
    end
  end
end

Syslog.info('okay no alert this time') if $nolog

db.close
Syslog.close