#--
# Copyright (c) 2006-2014, John Mettraux, jmettraux@gmail.com
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# Made in Japan.
#++

require 'date' if RUBY_VERSION < '1.9.0'
require 'time'
require 'thread'
require 'tzinfo'


module Rufus

  class Scheduler

    require 'rufus/scheduler/util'
    require 'rufus/scheduler/jobs'
    require 'rufus/scheduler/cronline'
    require 'rufus/scheduler/job_array'
    require 'rufus/scheduler/locks'

    VERSION = '3.0.9'

    #
    # A common error class for rufus-scheduler
    #
    class Error < StandardError; end

    #
    # This error is thrown when the :timeout attribute triggers
    #
    class TimeoutError < Error; end

    #
    # For when the scheduler is not running
    # (it got shut down or didn't start because of a lock)
    #
    class NotRunningError < Error; end

    #MIN_WORK_THREADS = 3
    MAX_WORK_THREADS = 28

    attr_accessor :frequency
    attr_reader :started_at
    attr_reader :thread
    attr_reader :thread_key
    attr_reader :mutexes

    #attr_accessor :min_work_threads
    attr_accessor :max_work_threads

    attr_accessor :stderr

    attr_reader :work_queue

    def initialize(opts={})

      @opts = opts

      @started_at = nil
      @paused = false

      @jobs = JobArray.new

      @frequency = Rufus::Scheduler.parse(opts[:frequency] || 0.300)
      @mutexes = {}

      @work_queue = Queue.new

      #@min_work_threads = opts[:min_work_threads] || MIN_WORK_THREADS
      @max_work_threads = opts[:max_work_threads] || MAX_WORK_THREADS

      @stderr = $stderr

      @thread_key = "rufus_scheduler_#{self.object_id}"

      @scheduler_lock =
        if lockfile = opts[:lockfile]
          Rufus::Scheduler::FileLock.new(lockfile)
        else
          opts[:scheduler_lock] || Rufus::Scheduler::NullLock.new
        end

      @trigger_lock = opts[:trigger_lock] || Rufus::Scheduler::NullLock.new

      # If we can't grab the @scheduler_lock, don't run.
      @scheduler_lock.lock || return

      start
    end

    # Returns a singleton Rufus::Scheduler instance
    #
    def self.singleton(opts={})

      @singleton ||= Rufus::Scheduler.new(opts)
    end

    # Alias for Rufus::Scheduler.singleton
    #
    def self.s(opts={}); singleton(opts); end

    # Releasing the gem would probably require redirecting .start_new to
    # .new and emit a simple deprecation message.
    #
    # For now, let's assume the people pointing at rufus-scheduler/master
    # on GitHub know what they do...
    #
    def self.start_new

      fail "this is rufus-scheduler 3.0, use .new instead of .start_new"
    end

    def shutdown(opt=nil)

      @started_at = nil

      #jobs.each { |j| j.unschedule }
        # provokes https://github.com/jmettraux/rufus-scheduler/issue/98
      @jobs.array.each { |j| j.unschedule }

      @work_queue.clear

      if opt == :wait
        join_all_work_threads
      elsif opt == :kill
        kill_all_work_threads
      end

      unlock
    end

    alias stop shutdown

    def uptime

      @started_at ? Time.now - @started_at : nil
    end

    def uptime_s

      self.class.to_duration(uptime)
    end

    def join

      fail NotRunningError.new(
        'cannot join scheduler that is not running'
      ) unless @thread

      @thread.join
    end

    def down?

      ! @started_at
    end

    def up?

      !! @started_at
    end

    def paused?

      @paused
    end

    def pause

      @paused = true
    end

    def resume

      @paused = false
    end

    #--
    # scheduling methods
    #++

    def at(time, callable=nil, opts={}, &block)

      do_schedule(:once, time, callable, opts, opts[:job], block)
    end

    def schedule_at(time, callable=nil, opts={}, &block)

      do_schedule(:once, time, callable, opts, true, block)
    end

    def in(duration, callable=nil, opts={}, &block)

      do_schedule(:once, duration, callable, opts, opts[:job], block)
    end

    def schedule_in(duration, callable=nil, opts={}, &block)

      do_schedule(:once, duration, callable, opts, true, block)
    end

    def every(duration, callable=nil, opts={}, &block)

      do_schedule(:every, duration, callable, opts, opts[:job], block)
    end

    def schedule_every(duration, callable=nil, opts={}, &block)

      do_schedule(:every, duration, callable, opts, true, block)
    end

    def interval(duration, callable=nil, opts={}, &block)

      do_schedule(:interval, duration, callable, opts, opts[:job], block)
    end

    def schedule_interval(duration, callable=nil, opts={}, &block)

      do_schedule(:interval, duration, callable, opts, true, block)
    end

    def cron(cronline, callable=nil, opts={}, &block)

      do_schedule(:cron, cronline, callable, opts, opts[:job], block)
    end

    def schedule_cron(cronline, callable=nil, opts={}, &block)

      do_schedule(:cron, cronline, callable, opts, true, block)
    end

    def schedule(arg, callable=nil, opts={}, &block)

      opts[:_t] = Scheduler.parse(arg, opts)

      case opts[:_t]
        when CronLine then schedule_cron(arg, callable, opts, &block)
        when Time then schedule_at(arg, callable, opts, &block)
        else schedule_in(arg, callable, opts, &block)
      end
    end

    def repeat(arg, callable=nil, opts={}, &block)

      opts[:_t] = Scheduler.parse(arg, opts)

      case opts[:_t]
        when CronLine then schedule_cron(arg, callable, opts, &block)
        else schedule_every(arg, callable, opts, &block)
      end
    end

    def unschedule(job_or_job_id)

      job, job_id = fetch(job_or_job_id)

      fail ArgumentError.new("no job found with id '#{job_id}'") unless job

      job.unschedule if job
    end

    #--
    # jobs methods
    #++

    # Returns all the scheduled jobs
    # (even those right before re-schedule).
    #
    def jobs(opts={})

      opts = { opts => true } if opts.is_a?(Symbol)

      jobs = @jobs.to_a

      if opts[:running]
        jobs = jobs.select { |j| j.running? }
      elsif ! opts[:all]
        jobs = jobs.reject { |j| j.next_time.nil? || j.unscheduled_at }
      end

      tags = Array(opts[:tag] || opts[:tags]).collect { |t| t.to_s }
      jobs = jobs.reject { |j| tags.find { |t| ! j.tags.include?(t) } }

      jobs
    end

    def at_jobs(opts={})

      jobs(opts).select { |j| j.is_a?(Rufus::Scheduler::AtJob) }
    end

    def in_jobs(opts={})

      jobs(opts).select { |j| j.is_a?(Rufus::Scheduler::InJob) }
    end

    def every_jobs(opts={})

      jobs(opts).select { |j| j.is_a?(Rufus::Scheduler::EveryJob) }
    end

    def interval_jobs(opts={})

      jobs(opts).select { |j| j.is_a?(Rufus::Scheduler::IntervalJob) }
    end

    def cron_jobs(opts={})

      jobs(opts).select { |j| j.is_a?(Rufus::Scheduler::CronJob) }
    end

    def job(job_id)

      @jobs[job_id]
    end

    # Returns true if the scheduler has acquired the [exclusive] lock and
    # thus may run.
    #
    # Most of the time, a scheduler is run alone and this method should
    # return true. It is useful in cases where among a group of applications
    # only one of them should run the scheduler. For schedulers that should
    # not run, the method should return false.
    #
    # Out of the box, rufus-scheduler proposes the
    # :lockfile => 'path/to/lock/file' scheduler start option. It makes
    # it easy for schedulers on the same machine to determine which should
    # run (the first to write the lockfile and lock it). It uses "man 2 flock"
    # so it probably won't work reliably on distributed file systems.
    #
    # If one needs to use a special/different locking mechanism, the scheduler
    # accepts :scheduler_lock => lock_object. lock_object only needs to respond
    # to #lock
    # and #unlock, and both of these methods should be idempotent.
    #
    # Look at rufus/scheduler/locks.rb for an example.
    #
    def lock

      @scheduler_lock.lock
    end

    # Sister method to #lock, is called when the scheduler shuts down.
    #
    def unlock

      @trigger_lock.unlock
      @scheduler_lock.unlock
    end

    # Callback called when a job is triggered. If the lock cannot be acquired,
    # the job won't run (though it'll still be scheduled to run again if
    # necessary).
    #
    def confirm_lock

      @trigger_lock.lock
    end

    # Returns true if this job is currently scheduled.
    #
    # Takes extra care to answer true if the job is a repeat job
    # currently firing.
    #
    def scheduled?(job_or_job_id)

      job, job_id = fetch(job_or_job_id)

      !! (job && job.next_time != nil)
    end

    # Lists all the threads associated with this scheduler.
    #
    def threads

      Thread.list.select { |t| t[thread_key] }
    end

    # Lists all the work threads (the ones actually running the scheduled
    # block code)
    #
    # Accepts a query option, which can be set to:
    # * :all (default), returns all the threads that are work threads
    #   or are currently running a job
    # * :active, returns all threads that are currenly running a job
    # * :vacant, returns the threads that are not running a job
    #
    # If, thanks to :blocking => true, a job is scheduled to monopolize the
    # main scheduler thread, that thread will get returned when :active or
    # :all.
    #
    def work_threads(query=:all)

      ts =
        threads.select { |t|
          t[:rufus_scheduler_job] || t[:rufus_scheduler_work_thread]
        }

      case query
        when :active then ts.select { |t| t[:rufus_scheduler_job] }
        when :vacant then ts.reject { |t| t[:rufus_scheduler_job] }
        else ts
      end
    end

    def running_jobs(opts={})

      jobs(opts.merge(:running => true))
    end

    def occurrences(time0, time1, format=:per_job)

      h = {}

      jobs.each do |j|
        os = j.occurrences(time0, time1)
        h[j] = os if os.any?
      end

      if format == :timeline
        a = []
        h.each { |j, ts| ts.each { |t| a << [ t, j ] } }
        a.sort_by { |(t, j)| t }
      else
        h
      end
    end

    def timeline(time0, time1)

      occurrences(time0, time1, :timeline)
    end

    def on_error(job, err)

      pre = err.object_id.to_s

      ms = {}; mutexes.each { |k, v| ms[k] = v.locked? }

      stderr.puts("{ #{pre} rufus-scheduler intercepted an error:")
      stderr.puts("  #{pre}   job:")
      stderr.puts("  #{pre}     #{job.class} #{job.original.inspect} #{job.opts.inspect}")
      # TODO: eventually use a Job#detail or something like that
      stderr.puts("  #{pre}   error:")
      stderr.puts("  #{pre}     #{err.object_id}")
      stderr.puts("  #{pre}     #{err.class}")
      stderr.puts("  #{pre}     #{err}")
      err.backtrace.each do |l|
        stderr.puts("  #{pre}       #{l}")
      end
      stderr.puts("  #{pre}   tz:")
      stderr.puts("  #{pre}     ENV['TZ']: #{ENV['TZ']}")
      stderr.puts("  #{pre}     Time.now: #{Time.now}")
      stderr.puts("  #{pre}   scheduler:")
      stderr.puts("  #{pre}     object_id: #{object_id}")
      stderr.puts("  #{pre}     opts:")
      stderr.puts("  #{pre}       #{@opts.inspect}")
      stderr.puts("  #{pre}       frequency: #{self.frequency}")
      stderr.puts("  #{pre}       scheduler_lock: #{@scheduler_lock.inspect}")
      stderr.puts("  #{pre}       trigger_lock: #{@trigger_lock.inspect}")
      stderr.puts("  #{pre}     uptime: #{uptime} (#{uptime_s})")
      stderr.puts("  #{pre}     down?: #{down?}")
      stderr.puts("  #{pre}     threads: #{self.threads.size}")
      stderr.puts("  #{pre}       thread: #{self.thread}")
      stderr.puts("  #{pre}       thread_key: #{self.thread_key}")
      stderr.puts("  #{pre}       work_threads: #{work_threads.size}")
      stderr.puts("  #{pre}         active: #{work_threads(:active).size}")
      stderr.puts("  #{pre}         vacant: #{work_threads(:vacant).size}")
      stderr.puts("  #{pre}         max_work_threads: #{max_work_threads}")
      stderr.puts("  #{pre}       mutexes: #{ms.inspect}")
      stderr.puts("  #{pre}     jobs: #{jobs.size}")
      stderr.puts("  #{pre}       at_jobs: #{at_jobs.size}")
      stderr.puts("  #{pre}       in_jobs: #{in_jobs.size}")
      stderr.puts("  #{pre}       every_jobs: #{every_jobs.size}")
      stderr.puts("  #{pre}       interval_jobs: #{interval_jobs.size}")
      stderr.puts("  #{pre}       cron_jobs: #{cron_jobs.size}")
      stderr.puts("  #{pre}     running_jobs: #{running_jobs.size}")
      stderr.puts("  #{pre}     work_queue: #{work_queue.size}")
      stderr.puts("} #{pre} .")

    rescue => e

      stderr.puts("failure in #on_error itself:")
      stderr.puts(e.inspect)
      stderr.puts(e.backtrace)

    ensure

      stderr.flush
    end

    protected

    # Returns [ job, job_id ]
    #
    def fetch(job_or_job_id)

      if job_or_job_id.respond_to?(:job_id)
        [ job_or_job_id, job_or_job_id.job_id ]
      else
        [ job(job_or_job_id), job_or_job_id ]
      end
    end

    def terminate_all_jobs

      jobs.each { |j| j.unschedule }

      sleep 0.01 while running_jobs.size > 0
    end

    def join_all_work_threads

      work_threads.size.times { @work_queue << :sayonara }

      work_threads.each { |t| t.join }

      @work_queue.clear
    end

    def kill_all_work_threads

      work_threads.each { |t| t.kill }
    end

    #def free_all_work_threads
    #
    #  work_threads.each { |t| t.raise(KillSignal) }
    #end

    def start

      @started_at = Time.now

      @thread =
        Thread.new do

          while @started_at do

            unschedule_jobs
            trigger_jobs unless @paused
            timeout_jobs

            sleep(@frequency)
          end
        end

      @thread[@thread_key] = true
      @thread[:rufus_scheduler] = self
      @thread[:name] = @opts[:thread_name] || "#{@thread_key}_scheduler"
    end

    def unschedule_jobs

      @jobs.delete_unscheduled
    end

    def trigger_jobs

      now = Time.now

      @jobs.each(now) do |job|

        job.trigger(now)
      end
    end

    def timeout_jobs

      work_threads(:active).each do |t|

        job = t[:rufus_scheduler_job]
        to = t[:rufus_scheduler_timeout]

        next unless job && to
          # thread might just have become inactive (job -> nil)

        ts = t[:rufus_scheduler_time]
        to = to.is_a?(Time) ? to : ts + to

        next if to > Time.now

        t.raise(Rufus::Scheduler::TimeoutError)
      end
    end

    def do_schedule(job_type, t, callable, opts, return_job_instance, block)

      fail NotRunningError.new(
        'cannot schedule, scheduler is down or shutting down'
      ) if @started_at == nil

      callable, opts = nil, callable if callable.is_a?(Hash)
      return_job_instance ||= opts[:job]

      job_class =
        case job_type
          when :once
            opts[:_t] ||= Rufus::Scheduler.parse(t, opts)
            opts[:_t].is_a?(Time) ? AtJob : InJob
          when :every
            EveryJob
          when :interval
            IntervalJob
          when :cron
            CronJob
        end

      job = job_class.new(self, t, opts, block || callable)

      raise ArgumentError.new(
        "job frequency (#{job.frequency}) is higher than " +
        "scheduler frequency (#{@frequency})"
      ) if job.respond_to?(:frequency) && job.frequency < @frequency

      @jobs.push(job)

      return_job_instance ? job : job.job_id
    end
  end
end

