import os
import std/strformat
import std/strutils
import sdl2
import sdl2/ttf

const
  WindowWidth = 900
  WindowHeight = 900
  OSWinX: cint = 1940
  OSWinY: cint = 50
  LineHeight = 20

type
  Cursor = object
    width: float
    height: float
    line_num: int = 0
    col: int = 0
    want_col: int = 0

  Buffer = object
    lines: seq[string]
    cursor: Cursor

func bufferNew(text: string, cursor: Cursor): Buffer =
  return Buffer(lines: text.split("\n"), cursor: cursor)

type SDLException = object of Defect

template sdlFailIf(condition: typed, reason: string) =
  if condition: raise SDLException.newException(
    reason & ", SDL error " & $getError()
  )

proc main =
  sdlFailIf(not sdl2.init(INIT_VIDEO or INIT_TIMER or INIT_EVENTS)):
    "SDL2 initialization failed"
  defer: sdl2.quit()

  let window = createWindow(
    title = "TODE",
    x = OSWinX,
    y = OSWinY,
    w = WindowWidth,
    h = WindowHeight,
    flags = SDL_WINDOW_SHOWN or SDL_WINDOW_RESIZABLE
  )

  sdlFailIf window.isNil: "window could not be created"
  defer: window.destroy()

  let renderer = createRenderer(
    window = window,
    index = -1,
    flags = Renderer_Accelerated or Renderer_PresentVsync or Renderer_TargetTexture
  )
  sdlFailIf renderer.isNil: "renderer could not be created"
  defer: renderer.destroy()

  sdlFailIf(not ttfInit()): "SDL_TTF initialization failed"
  defer: ttfQuit()

  let font = ttf.openFont("liberation-sans.ttf", 18)
  sdlFailIf font.isNil: "font could not be created"

  sdlFailIf(not setHint("SDL_RENDER_SCALE_QUALITY", "2")):
     "Linear texture filtering could not be enabled"

  var
    running = true
    dt: float32
    counter: uint64
    previousCounter: uint64
    
  let
    textFile = readFile("../../gux/test.c")
    cursor = Cursor(width: 8, height: LineHeight)
    buffer = bufferNew(textFile, cursor)

  counter = getPerformanceCounter()

  while running:
    previousCounter = counter
    counter = getPerformanceCounter()

    dt = (counter - previousCounter).float / getPerformanceFrequency().float

    var event = defaultEvent

    while pollEvent(event):
      case event.kind
      of QuitEvent:
        running = false
        break
      of KeyDown:
        discard
      of KeyUp:
        discard
      else:
        discard

    renderer.setDrawColor 255, 255, 255, 255 # black
    renderer.clear()

    for i, line in buffer.lines:
      if isEmptyOrWhitespace(line):
        continue
      let
        textColor = color(0, 0, 0, 0)
        surface = ttf.renderTextBlended(font, line, textColor)
        texture = renderer.createTextureFromSurface(surface)

      sdlFailIf surface.isNil: "Could not render text surface"
      var r = rect(0, cint(i * 20), surface.w, surface.h)

      renderer.copy texture, nil, addr r

      surface.freeSurface
      defer: texture.destroy

    renderer.present()

main()