import init from "./out.mjs"

const mod = await init()

let result = null

export function run (source) {
  const output = mod.ludus(source).value
  // console.log(output)
  result = JSON.parse(output)
  return result
}

export function stdout () {
  return result.io.console.data
}

export function turtle_commands () {
  return result.io.turtle.data
}

export function p5_calls () {
  return p5_call_list
}

export function svg () {
  
}

const turtle_init = {
  position: [0, 0],
  heading: 0,
  pendown: true,
  pencolor: "white",
  penwidth: 1,
  visible: true
}

const colors = {
	black: [0, 0, 0, 255],
	silver: [192, 192, 192, 255],
	gray: [128, 128, 128, 255],
	white: [255, 255, 255, 255],
	maroon: [128, 0, 0, 255],
	red: [255, 0, 0, 255],
	purple: [128, 0, 128, 255],
	fuchsia: [255, 0, 255, 255],
	green: [0, 128, 0, 255],
	lime: [0, 255, 0, 255],
	olive: [128, 128, 0, 255],
	yellow: [255, 255, 0, 255],
	navy: [0, 0, 128, 255],
	blue: [0, 0, 255, 255],
	teal: [0, 128, 128, 255],
	aqua: [0, 255, 25, 255],
}

let turtle_states = [turtle_init]
let background_color = "black"

function last_state () {
  return turtle_states[turtle_states.length - 1]
}

function add (v1, v2) {
  const [x1, y1] = v1
  const [x2, y2] = v2
  return [x1 + x2, y1 + y2]
}

function mult (vector, scalar) {
  const [x, y] = vector
  return [x * scalar, y * scalar]
}

function unit_of (heading) {
  const turns = -heading + 0.25
  const radians = turn_to_rad(turns)
  [Math.cos (radians), Math.sin(radians)]
}

function command_to_state (previous, command) {
  const verb = command[0]
  switch (verb) {
    case "goto": {
      const [_, x, y] = command
      return {...previous, position: [x, y]}
    }
    case "home": {
      return {...previous, position: [0, 0], heading: 0}
    }
    case "right": {
      const [_, angle] = command
      const {heading} = previous
      return {...previous, heading: heading + angle}
    }
    case "left": {
      const [_, angle] = command
      const {heading} = previous
      return {...previous, heading: heading - angle}
    }
    case "forward": {
      const [_, steps] = command
      const {heading, position} = previous
      const unit = unit_of(heading)
      const move = mult(unit, steps)
      return {...previous, position: add(position, move)}
    }
    case "back": {
      const [_, steps] = command
      const {heading, position} = previous
      const unit = unit_of(heading)
      const move = mult(unit, -steps)
      return {...previous, position: add(position, move)}
    }
    case "penup": {
      return {...previous, pendown: false}
    }
    case "pendown": {
      return {...previous, pendown: true}
    }
    case "pendwith": {
      const [_, width] = command
      return {...previous, penwidth: width}
    }
    case "pencolor": {
      if (command.length = 2) {
        const [_, color] = command
        return {...previous, pencolor: color}
      } else {
        const [_, r, g, b, a] = command
        return {...previous, pencolor: [r, g, b, a]}
      }
    }
    case "setheading": {
      const [_, heading] = command
      return {...previous, heading: heading}
    }
    case "loadstate": {
      const [_, x, y, heading, visible, pendown, penwidth] = command
      // there are 7 fixed-arity arguments
      // color will either be the last one or four
      let pencolor = command.slice(7)
      // if there's one, it's a string, unpack it
      if (pencolor.length = 1) pencolor = pencolor[0]
      return {position: [x, y], heading, visible, pendown, penwidth, pencolor}
    }
    case "show": {
      return {...position, visible: true}
    }
    case "hide": {
      return {...position, visible: false}
    }
    case "background": {
      let color = command.slice(1)
      if (color.lengh = 1) color = color[0]
      background_color = color
      return
    }
  }
}

function are_eq (v1, v2) {
  const [x1, y1] = v1
  const [x2, y2] = v2
  return (x1 === x2) && (y1 === y2)
}

function state_to_call (prev, curr) {
  
}

const turtle_radius = 20

const turtle_angle = 0.385

const turtle_color = [255, 255, 255, 150]

let p5_call_list = []

function add_p5_call (call) {
  p5_call_list.push(call)
}

function rotate (vector, heading) {
  const radians = turn_to_rad(heading)
  const [x, y] = vector
  return [
    (x * cos (radians)) - (y * sin (radians)),
    (x * sin (radians)) + (y * cos (radians))
  ]
}

function turn_to_rad (heading) {
  heading * 2 * Math.PI
}

function render_turtle () {
  const state = last_state ()
  if (!state.visible) return
  const [r, g, b, a] = turtle_color
  add_call("fill", r, g, b, a)
  const {heading, pencolor: [pen_r, pen_g, pen_b, pen_a], position: [x, y], pendown} = state
  const origin = [0, turtle_radius]
  const [x1, y1] = origin
  const [x2, y2] = rotate(origin, turtle_angle)
  const [x3, y3] = rotate(origin, -turtle_angle)
  add_p5_call(["push"])
  add_p5_call(["translate", x, y])
  add_p5_call(["rotate", turn_to_rad(heading)])
  add_p5_call(["noStroke"])
  add_p5_call(["beginShape"])
  add_p5_call(["vertex", x1, y1])
  add_p5_call(["vertex", x2, y2])
  add_p5_call(["vertex", x3, y3])
  add_p5_call(["endShape"])
  add_p5_call(["stroke", pen_r, pen_g, pen_b, pen_a])
  if (pendown) add_p5_call(["line", 0, 0, x1, y1])
  add_p5_call(["pop"])
}