import
  ValueStream, EventStream, IOStream,
  Error, Op, Input, val, evt
from require 'alv.base'
import monotime from require 'system'

class Clock extends IOStream
  new: (@frametime) =>
    super 'clock'

    return unless monotime
    @last = monotime!
    @dt = 0

  poll: =>
    time = monotime!
    @dt = time - @last
    if @dt >= @frametime
      @add { dt: @dt, :time }
      @last = time

class ScaledClock extends EventStream
  set: (val) => @value
  unwrap: => @value

clock = ValueStream.meta
  meta:
    name: 'clock'
    summary: "Create a clock source."
    examples: { '(clock)', '(clock fps)' }
    description: "Creates a new clock event stream.

The clock event stream is an IO that triggers other operators at a fixed
frame rate.

- `fps` has to be an eval-time constant and defaults to `60` if omitted."
  value: class extends Op
    new: (...) =>
      super ...
      @out or= Clock!

    setup: (inputs) =>
      fps = (-val.num)\match inputs
      super fps: Input.hot fps or ValueStream.num 60
      @out.frametime = 1 / @inputs.fps!

    tick: =>
      @out.frametime = 1 / @inputs.fps!

scale_time = ValueStream.meta
  meta:
    name: 'scale-time'
    summary: "Scale clock time."
    examples: { '(scale-time [clock] scale)' }
    description: "Creates a new clock event stream scaled by `scale`.

- `clock` should be a `time/clock` event stream. This argument can be omitted
  and the stream be passed as a dynamic definition in `*clock*` instead.
- `scale` should be a num-value."
  value: class extends Op
    new: (...) =>
      super ...
      @out or= EventStream 'clock'

    pattern = -evt.clock + val.num + -val.str
    setup: (inputs, scope) =>
      { clock, scale } = pattern\match inputs
      super
        clock: Input.hot clock or scope\get '*clock*'
        scale: Input.cold scale

    tick: =>
      scale = @inputs.scale!
      for evt in *@inputs.clock!
        @out\add {k, v*scale for k,v in pairs evt}

lfo = ValueStream.meta
  meta:
    name: 'lfo'
    summary: "Low-frequency oscillator."
    examples: { '(lfo [clock] freq [wave])' }
    description: "Oscillates betwen `0` and `1` at the frequency `freq`.

- `clock` should be a `time/clock` event stream. This argument can be omitted
  and the stream be passed as a dynamic definition in `*clock*` instead.
- `freq` should be a num-value.
- `wave` selects the wave shape from one of the following:
  - `'sin'` (the default)
  - `'saw'`
  - `'tri'`"
  value: class extends Op
    new: (...) =>
      super ...
      @state or= 0
      @out or= ValueStream 'num'

    default_wave = ValueStream.str 'sin'
    pattern = -evt.clock + val.num + -val.str
    setup: (inputs, scope) =>
      { clock, freq, wave } = pattern\match inputs
      super
        clock: Input.hot clock or scope\get '*clock*'
        freq: Input.cold freq
        wave: Input.hot wave or default_wave

    tau = math.pi * 2
    tick: =>
      for tick in *@inputs.clock!
        @state += tick.dt * @inputs.freq!

      @out\set switch @inputs.wave!
        when 'sin' then .5 + .5 * math.cos @state * tau
        when 'saw' then @state % 1
        when 'tri' then math.abs (2*@state % 2) - 1
        else error Error 'argument', "unknown wave type '#{wave}'"

ramp = ValueStream.meta
  meta:
    name: 'ramp'
    summary: "Sawtooth LFO."
    examples: { '(ramp [clock] period [max])' }
    description: "Ramps from `0` to `max` once every `period` seconds.

- `clock` should be a `time/clock` event stream. This argument can be omitted
  and the stream be passed as a dynamic definition in `*clock*` instead.
- `period` should be a num-value.
- `max` should be a num-value and defaults to `period` if omitted."
  value: class extends Op
    new: (...) =>
      super ...
      @state or= 0
      @out or= ValueStream 'num'

    pattern = -evt.clock + val.num + -val.num
    setup: (inputs, scope) =>
      { clock, period, max } = pattern\match inputs
      super
        clock: Input.hot clock or scope\get '*clock*'
        period: Input.cold period
        max: max and Input.cold max

    tick: =>
      for tick in *@inputs.clock!
        period = @inputs.period!
        max = (@inputs.max or @inputs.period)!
        @phase += tick.dt / period

      while @phase >= 1
        @phase -= 1

      @out\set @phase * max

tick = ValueStream.meta
  meta:
    name: 'tick'
    summary: "Count ticks."
    examples: { '(tick [clock] period)' }
    description: "Counts upwards by one every `period` seconds.

- `clock` should be a `time/clock` event stream. This argument can be omitted
  and the stream be passed as a dynamic definition in `*clock*` instead.
- `period` should be a num-value.
- returns a `num` value that increases by 1 every `period`."
  value: class extends Op
    new: (...) =>
      super ...
      @state or= { phase: 0, count: 0 }
      @out or= ValueStream 'num', @state.count

    pattern = -evt.clock + val.num
    setup: (inputs, scope) =>
      { clock, period } = pattern\match inputs
      super
        clock: Input.hot clock or scope\get '*clock*'
        period: Input.cold period

    tick: =>
      for tick in *@inputs.clock!
        @state.phase += tick.dt / @inputs.period!

      while @state.phase >= 1
        @state.phase -= 1
        @state.count += 1
        @out\set @state.count

every = ValueStream.meta
  meta:
    name: 'every'
    summary: "Emit events regularly."
    examples: { '(every [clock] period [evt])' }
    description: "Emits `evt` as an event once every `period` seconds.

- `clock` should be a `time/clock` event stream. This argument can be omitted
  and the stream be passed as a dynamic definition in `*clock*` instead.
- `period` should be a num-value.
- `evt` can be a value of any type. It defaults to `bang`.
- the return type will be an event stream with the same type as `evt`."
  value: class extends Op
    new: (...) =>
      super ...
      @state or= 0

    pattern = -evt.clock + val.num + -val!
    setup: (inputs, scope) =>
      { clock, period, evt } = pattern\match inputs
      super
        clock: Input.hot clock or scope\get '*clock*'
        period: Input.cold period
        evt: Input.cold evt or ValueStream 'bang', true
      @out = EventStream @inputs.evt\type!

    tick: =>
      for tick in *@inputs.clock!
        @state += tick.dt / @inputs.period!

      while @state >= 1
        @state -= 1
        @out\add @inputs.evt!

sequence = ValueStream.meta
  meta:
    name: 'sequence'
    summary: "Emit a sequence of values as events over time."
    examples: { '(sequence [clock] delay0 evt1 delay1 evt2 delay2…)' }
    description: "
Emits `evt1`, `evt2`, … as events with delays `delay0`, `delay1`, … in between.

- `clock` should be a `time/clock` event stream. This argument can be omitted
  and the stream be passed as a dynamic definition in `*clock*` instead.
- `delay0`, `delay1`, … must be num-values.
- `evt1`, `evt2`, … must be values of the same type.
- the return type will be an event stream with the same type as the `evt`s."
  value: class extends Op
    new: (...) =>
      super ...
      @state or= { i: 1, t: 0 }

    pair = (val! + val.num)\named('value', 'delay')
    pattern = -evt.clock + val.num + pair*0

    inputify = (step) ->
      {
        delay: Input.cold step.delay
        value: if step.value then Input.hot step.value
      }

    setup: (inputs, scope) =>
      { clock, first, steps } = pattern\match inputs
      @out = EventStream steps[1].value\type!
      table.insert steps, 1, { delay: first }
      super
        clock: Input.hot clock or scope\get '*clock*'
        steps: [inputify step for step in *steps]

    tick: =>
      for tick in *@inputs.clock!
        @state.t += tick.dt

      change, current = false, nil
      while true
        current = @inputs.steps[@state.i]
        if @state.t >= current.delay!
          @state.t -= current.delay!
          @state.i = 1 + (@state.i % #@inputs.steps)
          change = true
        else
          break

      if current.value and (change or current.value\dirty!)
        @out\add current.value!

{
  :clock
  'scale-time': scale_time
  :lfo
  :ramp
  :tick
  :every
  :sequence
  '*clock*': with Clock 1/60
    .meta =
      name: '*clock*'
      summary: 'Default clock source (60fps).'
}