# -*- encoding: binary -*-
# :stopdoc:
# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net>
# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
module DTAS::Player::ClientHandler

  # returns true on success, wait_ctl arg on error
  def set_bool(io, kv, v)
    case v
    when "false" then yield(false)
    when "true" then yield(true)
    else
      return io.emit("ERR #{kv} must be true or false")
    end
    true
  end

  def adjust_numeric(io, obj, k, v)
    negate = !!v.sub!(/\A-/, '')
    case v
    when %r{\A\+?\d*\.\d+\z}
      num = v.to_f
    when %r{\A\+?\d+\z}
      num = v.to_i
    else
      return io.emit("ERR #{k}=#{v} must be a float")
    end
    num = -num if negate

    if k.sub!(/\+\z/, '') # increment existing
      num += obj.__send__(k)
    elsif k.sub!(/-\z/, '') # decrement existing
      num = obj.__send__(k) - num
    # else # normal assignment
    end
    obj.__send__("#{k}=", num)
    true
  end

  # returns true on success, wait_ctl arg on error
  def set_int(io, kv, v, null_ok)
    case v
    when %r{\A-?\d+\z}
      yield(v.to_i)
    when ""
      null_ok or return io.emit("ERR #{kv} must be defined")
      yield(nil)
    else
      return io.emit("ERR #{kv} must an integer")
    end
    true
  end

  # returns true on success, wait_ctl arg on error
  def set_uint(io, kv, v, null_ok)
    case v
    when %r{\A\d+\z}
      yield(v.to_i)
    when %r{\A0x[0-9a-fA-F]+\z}i # hex
      yield(v.to_i(16))
    when ""
      null_ok or return io.emit("ERR #{kv} must be defined")
      yield(nil)
    else
      return io.emit("ERR #{kv} must an non-negative integer")
    end
    true
  end

  def __sink_activate(sink)
    return if sink.pid
    @targets.concat(sink.spawn(@format))
    @targets.sort_by! { |t| t.sink.prio }
  end

  def drop_sink(sink)
    @targets.delete_if do |t|
      if t.sink == sink
        drop_target(t)
        true
      else
        false
      end
    end
  end

  # called to activate/deactivate a sink
  def __sink_switch(sink)
    if sink.active
      if @current
        # maybe it's still alive for now, but it's just being killed
        # do not reactivate it until we've reaped it
        if sink.pid
          drop_sink(sink)
          sink.respawn = true
        else
          __sink_activate(sink)
        end
      end
    else
      drop_sink(sink)
    end
    # if we change any sinks, make sure the event loop watches it for
    # readability again, since we new sinks should be writable, and
    # we've stopped waiting on killed sinks
    @srv.wait_ctl(@sink_buf, :wait_readable)
  end

  # returns a wait_ctl arg
  def sink_handler(io, msg)
    name = msg[1]
    case msg[0]
    when "ls"
      io.emit(Shellwords.join(@sinks.keys.sort))
    when "rm"
      sink = @sinks.delete(name) or return io.emit("ERR #{name} not found")
      drop_sink(sink)
      io.emit("OK")
    when "ed"
      sink = @sinks[name] || (new_sink = DTAS::Sink.new)

      # allow things that look like audio device names ("hw:1,0" , "/dev/dsp")
      # or variable names.
      sink.valid_name?(name) or return io.emit("ERR sink name invalid")

      sink.name = name
      active_before = sink.active

      # multiple changes may be made at once
      msg[2..-1].each do |kv|
        k, v = kv.split(/=/, 2)
        case k
        when %r{\Aenv\.([^=]+)\z}
          sink.env[$1] = v
        when %r{\Aenv#([^=]+)\z}
          v == nil or return io.emit("ERR unset env has no value")
          sink.env.delete($1)
        when "prio"
          rv = set_int(io, kv, v, false) { |i| sink.prio = i }
          rv == true or return rv
          @targets.sort_by! { |t| t.sink.prio } if sink.active
        when "nonblock", "active"
          rv = set_bool(io, kv, v) { |b| sink.__send__("#{k}=", b) }
          rv == true or return rv
        when "pipe_size"
          rv = set_uint(io, kv, v, true) { |u| sink.__send__("#{k}=", u) }
          rv == true or return rv
        when "command" # nothing to validate, this could be "rm -rf /" :>
          sink.command = v.empty? ? DTAS::Sink::SINK_DEFAULTS["command"] : v
        end
      end

      @sinks[name] = new_sink if new_sink # no errors? it's a new sink!

      # start or stop a sink if its active= flag changed.  Additionally,
      # account for a crashed-but-marked-active sink.  The user may have
      # fixed the command to not crash it.
      if (active_before != sink.active) || (sink.active && !sink.pid)
        __sink_switch(sink)
      end
      io.emit("OK")
    when "cat"
      sink = @sinks[name] or return io.emit("ERR #{name} not found")
      io.emit(sink.to_hsh.to_yaml)
    else
      io.emit("ERR unknown sink op #{msg[0]}")
    end
  end

  def bytes_decoded(src = @current)
    bytes = src.dst.bytes_xfer - src.dst_zero_byte
    bytes = bytes < 0 ? 0 : bytes # maybe negative in case of sink errors
  end

  def __seek_offset_adj(dir, offset)
    if offset.sub!(/s\z/, '')
      offset = offset.to_i
    else # time
      offset = @current.format.hhmmss_to_samples(offset)
    end
    n = __current_decoded_samples + (dir * offset)
    n = 0 if n < 0
    "#{n}s"
  end

  def __current_decoded_samples
    initial = @current.offset_samples
    decoded = @format.bytes_to_samples(bytes_decoded)
    decoded = out_samples(decoded, @format, @current.format)
    initial + decoded
  end

  def __current_requeue
    return unless @current && @current.pid

    # no need to requeue if we're already due to die
    return if @current.requeued
    @current.requeued = true

    dst = @current.dst
    # prepare to seek to the desired point based on the number of bytes which
    # passed through dst buffer we want the offset for the @current file,
    # which may have a different rate than our internal @format
    if @current.respond_to?(:infile)
      # this offset in the @current.format (not player @format)
      @queue.unshift([ @current.infile, "#{__current_decoded_samples}s" ])
    else
      # DTAS::Source::Command (hash), just rerun it
      @queue.unshift(@current.to_hsh)
    end
    # We also want to hard drop the buffer so we do not get repeated audio.
    __buf_reset(dst)
  end

  def out_samples(in_samples, infmt, outfmt)
    in_rate = infmt.rate
    out_rate = outfmt.rate
    return in_samples if in_rate == out_rate # easy!
    (in_samples * out_rate / in_rate.to_f).round
  end

  # returns the number of samples we expect from the source
  # this takes into account sample rate differences between the source
  # and internal player format
  def current_expect_samples(in_samples) # @current.samples
    out_samples(in_samples, @current.format, @format)
  end

  def rg_handler(io, msg)
    return io.emit(@rg.to_hsh.to_yaml) if msg.empty?
    before = @rg.to_hsh
    msg.each do |kv|
      k, v = kv.split(/=/, 2)
      case k
      when "mode"
        case v
        when "off"
          @rg.mode = nil
        else
          DTAS::RGState::RG_MODE.include?(v) or
            return io.emit("ERR rg mode invalid")
          @rg.mode = v
        end
      when "fallback_track"
        rv = set_bool(io, kv, v) { |b| @rg.fallback_track = b }
        rv == true or return rv
      when %r{(?:gain_threshold|norm_threshold|
              preamp|norm_level|fallback_gain)[+-]?\z}x
        rv = adjust_numeric(io, @rg, k, v)
        rv == true or return rv
      end
    end
    after = @rg.to_hsh
    __current_requeue if before != after
    io.emit("OK")
  end

  def active_sinks
    sinks = @targets.map { |t| t.sink }
    sinks.uniq!
    sinks
  end

  # show current info about what's playing
  # returns non-blocking iterator retval
  def current_handler(io, msg)
    tmp = {}
    if @current
      tmp["current"] = s = @current.to_hsh
      s["spawn_at"] = @current.spawn_at
      s["pid"] = @current.pid

      # this offset and samples in the player @format (not @current.format)
      decoded = @format.bytes_to_samples(bytes_decoded)
      if @current.respond_to?(:infile)
        initial = tmp["current_initial"] = @current.offset_samples
        initial = out_samples(initial, @current.format, @format)
        tmp["current_expect"] = current_expect_samples(s["samples"])
        s["format"] = @current.format.to_hash.delete_if { |_,v| v.nil? }
      else
        initial = 0
        tmp["current_expect"] = nil
        s["format"] = @format.to_hash.delete_if { |_,v| v.nil? }
      end
      tmp["current_offset"] = initial + decoded
    end
    tmp["current_inflight"] = @sink_buf.inflight
    tmp["format"] = @format.to_hash.delete_if { |_,v| v.nil? }
    tmp["paused"] = @paused
    rg = @rg.to_hsh
    tmp["rg"] = rg unless rg.empty?
    if @targets[0]
      sinks = active_sinks
      tmp["sinks"] = sinks.map! do |sink|
        h = sink.to_hsh
        h["pid"] = sink.pid
        h
      end
    end
    io.emit(tmp.to_yaml)
  end

  def __buf_reset(buf)
    @srv.wait_ctl(buf, :ignore)
    buf.buf_reset
    @srv.wait_ctl(buf, :wait_readable)
  end

  def skip_handler(io, msg)
    __current_drop
    echo("skip")
    io.emit("OK")
  end

  def play_pause_handler(io, command)
    prev = @paused
    __send__("do_#{command}")
    io.emit({
      "paused" => {
        "before" => prev,
        "after" => @paused,
      }
    }.to_yaml)
  end

  def do_pause
    return if @paused
    echo("pause")
    @paused = true
    __current_requeue
  end

  def do_play
    # no echo, next_source will echo on new track
    @paused = false
    return if @current && @current.pid
    next_source(@queue.shift)
  end

  def do_play_pause
    @paused ? do_play : do_pause
  end

  def do_seek(io, offset)
    if @current && @current.pid
      if @current.respond_to?(:infile)
        begin
          if offset.sub!(/\A\+/, '')
            offset = __seek_offset_adj(1, offset)
          elsif offset.sub!(/\A-/, '')
            offset = __seek_offset_adj(-1, offset)
          # else: pass to sox directly
          end
        rescue ArgumentError
          return io.emit("ERR bad time format")
        end
        @queue.unshift([ @current.infile, offset ])
        __buf_reset(@current.dst) # trigger EPIPE
      else
        return io.emit("ERR unseekable")
      end
    elsif @paused
      case file = @queue[0]
      when String
        @queue[0] = [ file, offset ]
      when Array
        file[1] = offset
      else
        return io.emit("ERR unseekable")
      end
    # unpaused case... what do we do?
    end
    io.emit("OK")
  end

  def restart_pipeline
    return if @paused
    __current_requeue
    @sinks.each_value { |sink| sink.respawn = sink.active }
    @targets.each { |t| drop_target(t) }.clear
  end

  def format_handler(io, msg)
    new_fmt = @format.dup
    msg.each do |kv|
      k, v = kv.split(/=/, 2)
      case k
      when "type"
        new_fmt.valid_type?(v) or return io.emit("ERR invalid file type")
        new_fmt.type = v
      when "channels", "bits", "rate"
        rv = set_uint(io, kv, v, false) { |u| new_fmt.__send__("#{k}=", u) }
        rv == true or return rv
      when "endian"
        new_fmt.valid_endian?(v) or return io.emit("ERR invalid endian")
        new_fmt.endian = v
      end
    end

    if new_fmt != @format
      restart_pipeline # calls __current_requeue

      # we must assign this after __current_requeue since __current_requeue
      # relies on the old @format for calculation
      @format = new_fmt
    end
    io.emit("OK")
  end

  def env_handler(io, msg)
    msg.each do |kv|
      case kv
      when %r{\A([^=]+)=(.*)\z}
        ENV[$1] = $2
      when %r{\A([^=]+)#}
        ENV.delete($1)
      else
        return io.emit("ERR bad env")
      end
    end
    io.emit("OK")
  end

  def source_handler(io, msg)
    case msg.shift
    when "cat"
      io.emit({
        "command" => @srccmd || DTAS::Source::SOURCE_DEFAULTS["command"],
        "env" => @srcenv,
      }.to_yaml)
    when "ed"
      before = [ @srccmd, @srcenv ].inspect
      msg.each do |kv|
        k, v = kv.split(/=/, 2)
        case k
        when "command"
          @srccmd = v.empty? ? nil : v
        when %r{\Aenv\.([^=]+)\z}
          @srcenv[$1] = v
        when %r{\Aenv#([^=]+)\z}
          v == nil or return io.emit("ERR unset env has no value")
          @srcenv.delete($1)
        end
      end
      after = [ @srccmd, @srcenv ].inspect
      __current_requeue if before != after
      io.emit("OK")
    else
      io.emit("ERR unknown source op")
    end
  end

  def chdir_handler(io, msg)
    msg.size == 1 or return io.emit("ERR usage: cd DIRNAME")
    begin
      Dir.chdir(msg[0])
    rescue => e
      return io.emit("ERR chdir: #{e.message}")
    end
    # echo(%W(cd msg[0])) # should we broadcast this?
    io.emit("OK")
  end
end