var render = use('render')
var graphics = use('graphics')
var math = use('math')
var util = use('util')
var os = use('os')
var geometry = use('geometry')

var draw = {}
draw[prosperon.DOC] = `
A collection of 2D drawing functions that operate in screen space. Provides primitives
for lines, rectangles, text, sprite drawing, etc. Immediate mode.
`

/*var whiteimage = {}
whiteimage = graphics.make_surface([1,1])
whiteimage.rect({x:0,y:0,width:1,height:1}, [1,1,1,1])
render.load_texture(whiteimage)
*/

if (render.point)
  draw.point = function(pos,size,opt = {color:Color.white}, pipeline) {
    render.settings(opt)
    render.pipeline(pipeline)
    render.point([pos])
  }
else
  draw.point = function() { throw new Error('Backend cannot draw points.') }
draw.point[prosperon.DOC] = `
:param pos: A 2D position ([x, y]) where the point should be drawn.
:param size: The size of the point.
:param color: The color of the point, defaults to white.
:return: None
`

/* ------------------------------------------------------------------------
 *  helper – is (dx,dy) inside the desired wedge?
 * -------------------------------------------------------------------- */
function within_wedge(dx, dy, start, end, full_circle)
{
  if (full_circle) return true

  var ang = Math.atan2(dy, dx)             // [-π,π]
  if (ang < 0) ang += Math.PI * 2
  var t = ang / (Math.PI * 2)              // turn ∈ [0,1)

  if (start <= end) return t >= start && t <= end
  return t >= start || t <= end            // wrap-around arc
}

/* ------------------------------------------------------------------------
 *  software ellipse – outline / ring / fill via inner_radius
 * -------------------------------------------------------------------- */
function software_ellipse(pos, radii, opt)
{
  var rx = radii[0], ry = radii[1]
  if (rx <= 0 || ry <= 0) return

  var cx = pos[0], cy = pos[1]
  var raw_start = opt.start
  var raw_end = opt.end
  var full_circle = Math.abs(raw_end - raw_start) >= 1 - 1e-9
  var start = (raw_start % 1 + 1) % 1
  var end = (raw_end % 1 + 1) % 1
  var thickness = Math.max(1, opt.thickness|0)

  /* inner ellipse radii (may be zero or negative → treat as no hole) */
  var rx_i = rx - thickness,
      ry_i = ry - thickness
  var hole = (rx_i > 0 && ry_i > 0)

  /* fast one-pixel outline ? --------------------------------------- */
  if (!hole && thickness === 1) {
    /* (same midpoint algorithm as before, filtered by wedge) --------*/
    var rx_sq = rx * rx, ry_sq = ry * ry
    var two_rx_sq = rx_sq << 1, two_ry_sq = ry_sq << 1
    var x = 0, y = ry, px = 0, py = two_rx_sq * y
    var p = ry_sq - rx_sq * ry + 0.25 * rx_sq

    function plot_pts(x, y) {
      var pts = [
        [cx + x, cy + y], [cx - x, cy + y],
        [cx + x, cy - y], [cx - x, cy - y]
      ].filter(pt => within_wedge(pt[0]-cx, pt[1]-cy, start, end, full_circle))
      if (pts.length) render.point(pts)
    }

    while (px < py) {
      plot_pts(x, y)
      ++x; px += two_ry_sq
      if (p < 0) p += ry_sq + px
      else { --y; py -= two_rx_sq; p += ry_sq + px - py }
    }
    p = ry_sq*(x+.5)*(x+.5) + rx_sq*(y-1)*(y-1) - rx_sq*ry_sq
    while (y >= 0) {
      plot_pts(x, y)
      --y; py -= two_rx_sq
      if (p > 0) p += rx_sq - py
      else { ++x; px += two_ry_sq; p += rx_sq - py + px }
    }
    return
  }

  /* ------------------------------------------------------------------
   *  FILL or RING (thickness ≥ 2  OR  hole == false -> full fill)
   * ---------------------------------------------------------------- */
  var strips = []
  var rx_sq  = rx * rx,  ry_sq  = ry * ry
  var rx_i_sq = rx_i * rx_i, ry_i_sq = ry_i * ry_i

  for (var dy = -ry; dy <= ry; ++dy) {
    var yy = dy * dy
    var x_out = Math.floor(rx * Math.sqrt(1 - yy / ry_sq))
    var y_screen = cy + dy

    /* optional inner span */
    var x_in = hole ? Math.floor(rx_i * Math.sqrt(1 - yy / ry_i_sq)) : -1

    var run_start = null
    for (var dx = -x_out; dx <= x_out; ++dx) {
      if (hole && Math.abs(dx) <= x_in) { run_start = null; continue }
      if (!within_wedge(dx, dy, start, end, full_circle)) { run_start = null; continue }

      if (run_start === null) run_start = cx + dx

      var last = (dx === x_out)
      var next_in_ring =
        !last &&
        !(hole && Math.abs(dx+1) <= x_in) &&
        within_wedge(dx+1, dy, start, end, full_circle)

      if (last || !next_in_ring) {
        strips.push({
          x: run_start,
          y: y_screen,
          width: (cx + dx) - run_start + 1,
          height: 1
        })
        run_start = null
      }
    }
  }
  if (strips.length) render.rects(strips)
}

var ellipse_def = {
  color: Color.white,
  start: 0,
  end: 1,
  mode: 'fill',
  thickness: 1,
}

if (render.ellipse)
  draw.ellipse = function(pos, radii, def, pipeline) {
  }
else
  draw.ellipse = function(pos, radii, def, pipeline) {
    var opt = def ? {...ellipse_def, ...def} : ellipse_def
    render.settings(opt)
    render.pipeline(pipeline)
    if (opt.thickness <= 0) opt.thickness = Math.max(radii[0], radii[1])
    software_ellipse(pos, radii, opt)
  }

var line_def = {
  color: Color.white,
  thickness: 1,
  cap:"butt", 
}

draw.line = function(points, def, pipeline)
{
  var opt
  if (def)
    opt = {...line_def, ...def}
  else
    opt = line_def
    
  render.settings(opt)
  render.pipeline(pipeline)
  render.line(points)
}

draw.cross = function render_cross(pos, size, def, pipe) {
  var a = [pos.add([0, size]), pos.add([0, -size])]
  var b = [pos.add([size, 0]), pos.add([-size, 0])]
  draw.line(a, def, pipe)
  draw.line(b, def,pipe)
}

draw.arrow = function render_arrow(start, end, wingspan = 4, wingangle = 10, def, pipe) {
  var dir = math.norm(end.sub(start))
  var wing1 = [math.rotate(dir, wingangle).scale(wingspan).add(end), end]
  var wing2 = [math.rotate(dir, -wingangle).scale(wingspan).add(end), end]
  draw.line([start, end], def, pipe)
  draw.line(wing1, def, pipe)
  draw.line(wing2, def, pipe)
}

/* ------------------------------------------------------------------------
 *  helper – plain rectangle outline of arbitrary thickness    (radius=0)
 * -------------------------------------------------------------------- */
function software_outline_rect(rect, thickness)
{
  if (thickness <= 0) {
    render.rectangle(rect);
    return;
  }

  /* stroke swallows the whole thing → fill instead */
  if ((thickness << 1) >= rect.width ||
      (thickness << 1) >= rect.height) {
    render.rectangle(rect)                 // filled
    return
  }

  const x0 = rect.x,
        y0 = rect.y,
        x1 = rect.x + rect.width,
        y1 = rect.y + rect.height

  render.rects([
    { x:x0,         y:y0,          width:rect.width, height:thickness },              // top
    { x:x0,         y:y1-thickness, width:rect.width, height:thickness },             // bottom
    { x:x0,         y:y0+thickness, width:thickness,
      height:rect.height - (thickness<<1) },                                          // left
    { x:x1-thickness, y:y0+thickness, width:thickness,
      height:rect.height - (thickness<<1) }                                           // right
  ])
}

/* ------------------------------------------------------------------------
 *  ROUNDED rectangle outline  (was software_round_rect)
 * -------------------------------------------------------------------- */
function software_round_rect(rect, radius, thickness = 1)
{
  if (thickness <= 0) {
    software_fill_round_rect(rect, radius)
    return
  }

  radius = Math.min(radius, rect.width >> 1, rect.height >> 1)

  /* stroke covers whole rect → fall back to fill ------------------- */
  if ((thickness << 1) >= rect.width ||
      (thickness << 1) >= rect.height ||
      thickness >= radius) {
    software_fill_round_rect(rect, radius)
    return
  }

  const x0 = rect.x,
        y0 = rect.y,
        x1 = rect.x + rect.width  - 1,   // inclusive
        y1 = rect.y + rect.height - 1

  const cx_l = x0 + radius,  cx_r = x1 - radius
  const cy_t = y0 + radius,  cy_b = y1 - radius
  const r_out = radius
  const r_in  = radius - thickness

  /* straight bands (top/bottom/left/right) ------------------------- */
  render.rects([
    { x:x0 + radius, y:y0,               width:rect.width - (radius << 1),
      height:thickness                                   },          // top
    { x:x0 + radius, y:y1 - thickness + 1,
      width:rect.width - (radius << 1), height:thickness },          // bottom
    { x:x0,           y:y0 + radius,     width:thickness,
      height:rect.height - (radius << 1)                 },          // left
    { x:x1 - thickness + 1, y:y0 + radius, width:thickness,
      height:rect.height - (radius << 1)                 }           // right
  ])

  /* corner arcs ---------------------------------------------------- */
  const strips = []

  for (let dy = 0; dy < radius; ++dy) {
    const dy_sq   = dy * dy
    const dx_out  = Math.floor(Math.sqrt(r_out * r_out - dy_sq))
    const dx_in   = (r_in > 0 && dy < r_in)
                  ? Math.floor(Math.sqrt(r_in * r_in - dy_sq))
                  : -1                                   // no inner rim
    const w = dx_out - dx_in                            // strip width
    if (w <= 0) continue

    /* top */
    strips.push(
      { x:cx_l - dx_out,      y:cy_t - dy, width:w, height:1 },   // NW
      { x:cx_r + dx_in + 1,   y:cy_t - dy, width:w, height:1 }    // NE
    )

    /* bottom */
    strips.push(
      { x:cx_l - dx_out,      y:cy_b + dy, width:w, height:1 },   // SW
      { x:cx_r + dx_in + 1,   y:cy_b + dy, width:w, height:1 }    // SE
    )
  }

  render.rects(strips)
}

/* ------------------------------------------------------------------------
 *  filled rounded rect  (unchanged)
 * -------------------------------------------------------------------- */
function software_fill_round_rect(rect, radius)
{
  radius = Math.min(radius, rect.width >> 1, rect.height >> 1)

  const x0 = rect.x,
        y0 = rect.y,
        x1 = rect.x + rect.width  - 1,
        y1 = rect.y + rect.height - 1

  /* main column */
  render.rects([
    { x:x0 + radius, y:y0, width:rect.width - (radius << 1),
      height:rect.height }
  ])

  /* side columns */
  render.rects([
    { x:x0,           y:y0 + radius, width:radius,
      height:rect.height - (radius << 1) },
    { x:x1 - radius + 1, y:y0 + radius, width:radius,
      height:rect.height - (radius << 1) }
  ])

  /* corner caps */
  const cx_l = x0 + radius,  cx_r = x1 - radius
  const cy_t = y0 + radius,  cy_b = y1 - radius
  const caps = []

  for (let dy = 0; dy < radius; ++dy) {
    const dx = Math.floor(Math.sqrt(radius * radius - dy * dy))
    const w  = (dx << 1) + 1

    caps.push(
      { x:cx_l - dx, y:cy_t - dy, width:w, height:1 },
      { x:cx_r - dx, y:cy_t - dy, width:w, height:1 },
      { x:cx_l - dx, y:cy_b + dy, width:w, height:1 },
      { x:cx_r - dx, y:cy_b + dy, width:w, height:1 }
    )
  }

  render.rects(caps)
}

var rect_def = {
  thickness:1,
  color: Color.white,
  radius: 0
}
draw.rectangle = function render_rectangle(rect, def, pipeline) {
  var opt = def ? {...rect_def, ...def} : rect_def
  render.settings(opt)
  render.pipeline(pipeline)

  var t = opt.thickness|0

  if (t <= 0) {
    if (opt.radius)
      software_fill_round_rect(rect, opt.radius)
    else
      render.rectangle(rect)

    return
  }

  if (opt.radius)
    software_round_rect(rect, opt.radius, t)
  else
    software_outline_rect(rect,t)
}

var slice9_info = {
  tile_top:true,
  tile_bottom:true,
  tile_left:true,
  tile_right:true,
  tile_center_x:true,
  tile_center_right:true,
  color: Color.white,
}

draw.slice9 = function slice9(image, rect = [0,0], slice = 0, info = slice9_info, pipeline) {
  if (!image) throw Error('Need an image to render.')
  if (typeof image === "string")
    image = graphics.texture(image)

  render.slice9(image, rect, slice, slice9_info, pipeline);
}
draw.slice9[prosperon.DOC] = `
:param image: An image object or string path to a texture.
:param rect: A rectangle specifying draw location/size, default [0, 0].
:param slice: The pixel inset or spacing for the 9-slice (number or object).
:param info: A slice9 info object controlling tiling of edges/corners.
:param pipeline: (Optional) A pipeline or rendering state object.
:return: None
:raises Error: If no image is provided.
`

var std_sprite_cmd = {type:'sprite', color:[1,1,1,1]}
var image_info = {
  tile_x: false,
  tile_y: false,
  flip_x: false,
  flip_y: false,
  color: Color.white,
}

draw.image = function image(image, rect = [0,0], rotation = 0, anchor = [0,0], shear = [0,0], info, pipeline) {
  if (!image) throw Error('Need an image to render.')
  if (typeof image === "string")
    image = graphics.texture(image)
  rect.width ??= image.texture.width
  rect.height ??= image.texture.height
  info ??= image_info;
  render.settings(info)
  render.image(image, rect, rotation, anchor, shear, info)
}

function software_circle(pos, radius)
{
  if (radius <= 0) return                   // nothing to draw

  var cx = pos[0], cy = pos[1]
  var x = 0, y = radius
  var d = 3 - (radius << 1)                 // decision parameter

  while (x <= y) {
    draw.point([
      [cx + x, cy + y], [cx - x, cy + y],
      [cx + x, cy - y], [cx - x, cy - y],
      [cx + y, cy + x], [cx - y, cy + x],
      [cx + y, cy - x], [cx - y, cy - x]
    ])

    if (d < 0) d += (x << 2) + 6
    else {
      d += ((x - y) << 2) + 10
      y--
    }
    x++
  }
}

var circle_def = {
  inner_radius:1, // percentage: 1 means filled circle
  color: Color.white,
  start:0,
  end: 1,
}
draw.circle = function render_circle(pos, radius, def, pipeline) {
  draw.ellipse(pos, [radius,radius], def, pipeline)
}

var sysfont = graphics.get_font('fonts/c64.ttf', 8)

draw.text = function text(text, rect, font = sysfont, size = 0, color = Color.white, wrap = 0, pipeline) {
  if (typeof font === 'string') font = graphics.get_font(font)
  var mesh = graphics.make_text_buffer(text, rect, 0, color, wrap, font)
  render.geometry(font, mesh)
}
draw.text[prosperon.DOC] = `
:param text: The string to draw.
:param rect: A rectangle specifying draw position (and possibly wrapping area).
:param font: A font object or string path, default sysfont.
:param size: (Unused) Possibly intended for scaling the font size.
:param color: The text color, default Color.white.
:param wrap: Pixel width for text wrapping, default 0 (no wrap).
:param pipeline: (Optional) A pipeline or rendering state object.
:return: None
`

return draw