#include <u.h>
#include <libc.h>
#include <draw.h>
#include <thread.h>
#include <cursor.h>
#include <mouse.h>
#include <keyboard.h>
#include "libframe/frame.h"
#include <fcall.h>
#include <plumb.h>
#include <libsec.h>
#include "dat.h"
#include "fns.h"

static Image* scrtmp;

static Rectangle scrpos(Rectangle r, uint p0, uint p1, uint tot) {
  Rectangle q;
  int h;

  q = r;
  h = q.max.y - q.min.y;
  if (tot == 0)
    return q;
  if (tot > 1024 * 1024) {
    tot >>= 10;
    p0 >>= 10;
    p1 >>= 10;
  }
  if (p0 > 0)
    q.min.y += h * p0 / tot;
  if (p1 < tot)
    q.max.y -= h * (tot - p1) / tot;
  if (q.max.y < q.min.y + 2) {
    if (q.min.y + 2 <= r.max.y)
      q.max.y = q.min.y + 2;
    else
      q.min.y = q.max.y - 2;
  }
  return q;
}

void scrlresize(void) {
  freeimage(scrtmp);
  scrtmp = allocimage(
    display,
    Rect(0, 0, 32, screen->r.max.y),
    screen->chan,
    0,
    DNofill);
  if (scrtmp == nil)
    error("scroll alloc");
}

void textscrdraw(Text* t) {
  Rectangle r, r1, r2;
  Image* b;

  if (t->w == nil || t != &t->w->body)
    return;
  if (scrtmp == nil)
    scrlresize();
  r = t->scrollr;
  b = scrtmp;
  r1 = r;
  r1.min.x = 0;
  r1.max.x = Dx(r);
  r2 = scrpos(r1, t->org, t->org + t->fr.nchars, t->file->b.nc);
  if (!eqrect(r2, t->lastsr)) {
    t->lastsr = r2;
    draw(b, r1, t->fr.cols[BORD], nil, ZP);
    draw(b, r2, t->fr.cols[BACK], nil, ZP);
    r2.min.x = r2.max.x - 1;
    draw(b, r2, t->fr.cols[BORD], nil, ZP);
    draw(t->fr.b, r, b, nil, Pt(0, r1.min.y));
    /*flushimage(display, 1); // BUG? */
  }
}

void scrsleep(uint dt) {
  Timer* timer;
  static Alt alts[3];

  timer = timerstart(dt);
  alts[0].c = timer->c;
  alts[0].v = nil;
  alts[0].op = CHANRCV;
  alts[1].c = mousectl->c;
  alts[1].v = &mousectl->m;
  alts[1].op = CHANRCV;
  alts[2].op = CHANEND;
  for (;;)
    switch (alt(alts)) {
      case 0:
        timerstop(timer);
        return;
      case 1:
        timercancel(timer);
        return;
    }
}

void textscroll(Text* t, int but) {
  uint p0, oldp0;
  Rectangle s;
  int x, y, my, h, first;

  s = insetrect(t->scrollr, 1);
  h = s.max.y - s.min.y;
  x = (s.min.x + s.max.x) / 2;
  oldp0 = ~0;
  first = TRUE;
  do {
    flushimage(display, 1);
    my = mouse->xy.y;
    if (my < s.min.y)
      my = s.min.y;
    if (my >= s.max.y)
      my = s.max.y;
    if (!eqpt(mouse->xy, Pt(x, my))) {
      moveto(mousectl, Pt(x, my));
      readmouse(mousectl); /* absorb event generated by moveto() */
    }
    if (but == 2) {
      y = my;
      p0 = (vlong)t->file->b.nc * (y - s.min.y) / h;
      if (p0 >= t->q1)
        p0 = textbacknl(t, p0, 2);
      if (oldp0 != p0)
        textsetorigin(t, p0, FALSE);
      oldp0 = p0;
      readmouse(mousectl);
      continue;
    }
    if (but == 1)
      p0 = textbacknl(t, t->org, (my - s.min.y) / t->fr.font->height);
    else
      p0 = t->org + frcharofpt(&t->fr, Pt(s.max.x, my));
    if (oldp0 != p0)
      textsetorigin(t, p0, TRUE);
    oldp0 = p0;
    /* debounce */
    if (first) {
      flushimage(display, 1);
      sleep(200);
      nbrecv(mousectl->c, &mousectl->m);
      first = FALSE;
    }
    scrsleep(80);
  } while (mouse->buttons & (1 << (but - 1)));
  while (mouse->buttons)
    readmouse(mousectl);
}