#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"
#include "edit.h"

static char Wsequence[] = "warning: changes out of sequence\n";
static int warned = FALSE;

/*
 * Log of changes made by editing commands.  Three reasons for this:
 * 1) We want addresses in commands to apply to old file, not file-in-change.
 * 2) It's difficult to track changes correctly as things move, e.g. ,x m$
 * 3) This gives an opportunity to optimize by merging adjacent changes.
 * It's a little bit like the Undo/Redo log in Files, but Point 3) argues for a
 * separate implementation.  To do this well, we use Replace as well as
 * Insert and Delete
 */

typedef struct Buflog Buflog;
struct Buflog {
  short type; /* Replace, Filename */
  uint q0;    /* location of change (unused in f) */
  uint nd;    /* # runes to delete */
  uint nr;    /* # runes in string or file name */
};

enum { Buflogsize = sizeof(Buflog) / sizeof(Rune) };

/*
 * Minstring shouldn't be very big or we will do lots of I/O for small changes.
 * Maxstring is RBUFSIZE so we can fbufalloc() once and not realloc elog.r.
 */
enum {
  Minstring = 16,      /* distance beneath which we merge changes */
  Maxstring = RBUFSIZE /* maximum length of change we will merge into one */
};

void eloginit(File* f) {
  if (f->elog.type != Empty)
    return;
  f->elog.type = Null;
  if (f->elogbuf == nil)
    f->elogbuf = emalloc(sizeof(Buffer));
  if (f->elog.r == nil)
    f->elog.r = fbufalloc();
  bufreset(f->elogbuf);
}

void elogclose(File* f) {
  if (f->elogbuf) {
    bufclose(f->elogbuf);
    free(f->elogbuf);
    f->elogbuf = nil;
  }
}

void elogreset(File* f) {
  f->elog.type = Null;
  f->elog.nd = 0;
  f->elog.nr = 0;
}

void elogterm(File* f) {
  elogreset(f);
  if (f->elogbuf)
    bufreset(f->elogbuf);
  f->elog.type = Empty;
  fbuffree(f->elog.r);
  f->elog.r = nil;
  warned = FALSE;
}

void elogflush(File* f) {
  Buflog b;

  b.type = f->elog.type;
  b.q0 = f->elog.q0;
  b.nd = f->elog.nd;
  b.nr = f->elog.nr;
  switch (f->elog.type) {
    default:
      warning(nil, "unknown elog type 0x%ux\n", f->elog.type);
      break;
    case Null:
      break;
    case Insert:
    case Replace:
      if (f->elog.nr > 0)
        bufinsert(f->elogbuf, f->elogbuf->nc, f->elog.r, f->elog.nr);
      /* fall through */
    case Delete:
      bufinsert(f->elogbuf, f->elogbuf->nc, (Rune*)&b, Buflogsize);
      break;
  }
  elogreset(f);
}

void elogreplace(File* f, int q0, int q1, Rune* r, int nr) {
  uint gap;

  if (q0 == q1 && nr == 0)
    return;
  eloginit(f);
  if (f->elog.type != Null && q0 < f->elog.q0) {
    if (warned++ == 0)
      warning(nil, Wsequence);
    elogflush(f);
  }
  /* try to merge with previous */
  gap = q0 - (f->elog.q0 + f->elog.nd); /* gap between previous and this */
  if (f->elog.type == Replace && f->elog.nr + gap + nr < Maxstring) {
    if (gap < Minstring) {
      if (gap > 0) {
        bufread(&f->b, f->elog.q0 + f->elog.nd, f->elog.r + f->elog.nr, gap);
        f->elog.nr += gap;
      }
      f->elog.nd += gap + q1 - q0;
      runemove(f->elog.r + f->elog.nr, r, nr);
      f->elog.nr += nr;
      return;
    }
  }
  elogflush(f);
  f->elog.type = Replace;
  f->elog.q0 = q0;
  f->elog.nd = q1 - q0;
  f->elog.nr = nr;
  if (nr > RBUFSIZE)
    editerror("internal error: replacement string too large(%d)", nr);
  runemove(f->elog.r, r, nr);
}

void eloginsert(File* f, int q0, Rune* r, int nr) {
  int n;

  if (nr == 0)
    return;
  eloginit(f);
  if (f->elog.type != Null && q0 < f->elog.q0) {
    if (warned++ == 0)
      warning(nil, Wsequence);
    elogflush(f);
  }
  /* try to merge with previous */
  if (
    f->elog.type == Insert && q0 == f->elog.q0 && f->elog.nr + nr < Maxstring) {
    runemove(f->elog.r + f->elog.nr, r, nr);
    f->elog.nr += nr;
    return;
  }
  while (nr > 0) {
    elogflush(f);
    f->elog.type = Insert;
    f->elog.q0 = q0;
    n = nr;
    if (n > RBUFSIZE)
      n = RBUFSIZE;
    f->elog.nr = n;
    runemove(f->elog.r, r, n);
    r += n;
    nr -= n;
  }
}

void elogdelete(File* f, int q0, int q1) {
  if (q0 == q1)
    return;
  eloginit(f);
  if (f->elog.type != Null && q0 < f->elog.q0 + f->elog.nd) {
    if (warned++ == 0)
      warning(nil, Wsequence);
    elogflush(f);
  }
  /* try to merge with previous */
  if (f->elog.type == Delete && f->elog.q0 + f->elog.nd == q0) {
    f->elog.nd += q1 - q0;
    return;
  }
  elogflush(f);
  f->elog.type = Delete;
  f->elog.q0 = q0;
  f->elog.nd = q1 - q0;
}

#define tracelog 0
void elogapply(File* f) {
  Buflog b;
  Rune* buf;
  uint i, n, up, mod;
  uint tq0, tq1;
  Buffer* log;
  Text* t;
  int owner;

  elogflush(f);
  log = f->elogbuf;
  t = f->curtext;

  buf = fbufalloc();
  mod = FALSE;

  owner = 0;
  if (t->w) {
    owner = t->w->owner;
    if (owner == 0)
      t->w->owner = 'E';
  }

  /*
   * The edit commands have already updated the selection in t->q0, t->q1,
   * but using coordinates relative to the unmodified buffer.  As we apply the
   * log, we have to update the coordinates to be relative to the modified
   * buffer. Textinsert and textdelete will do this for us; our only work is to
   * apply the convention that an insertion at t->q0==t->q1 is intended to
   * select the inserted text.
   */

  /*
   * We constrain the addresses in here (with textconstrain()) because
   * overlapping changes will generate bogus addresses.   We will warn
   * about changes out of sequence but proceed anyway; here we must
   * keep things in range.
   */

  while (log->nc > 0) {
    up = log->nc - Buflogsize;
    bufread(log, up, (Rune*)&b, Buflogsize);
    switch (b.type) {
      default:
        fprint(2, "elogapply: 0x%ux\n", b.type);
        abort();
        break;

      case Replace:
        if (tracelog)
          warning(
            nil,
            "elog replace %d %d (%d %d)\n",
            b.q0,
            b.q0 + b.nd,
            t->q0,
            t->q1);
        if (!mod) {
          mod = TRUE;
          filemark(f);
        }
        textconstrain(t, b.q0, b.q0 + b.nd, &tq0, &tq1);
        textdelete(t, tq0, tq1, TRUE);
        up -= b.nr;
        for (i = 0; i < b.nr; i += n) {
          n = b.nr - i;
          if (n > RBUFSIZE)
            n = RBUFSIZE;
          bufread(log, up + i, buf, n);
          textinsert(t, tq0 + i, buf, n, TRUE);
        }
        if (t->q0 == b.q0 && t->q1 == b.q0)
          t->q1 += b.nr;
        break;

      case Delete:
        if (tracelog)
          warning(
            nil,
            "elog delete %d %d (%d %d)\n",
            b.q0,
            b.q0 + b.nd,
            t->q0,
            t->q1);
        if (!mod) {
          mod = TRUE;
          filemark(f);
        }
        textconstrain(t, b.q0, b.q0 + b.nd, &tq0, &tq1);
        textdelete(t, tq0, tq1, TRUE);
        break;

      case Insert:
        if (tracelog)
          warning(
            nil,
            "elog insert %d %d (%d %d)\n",
            b.q0,
            b.q0 + b.nr,
            t->q0,
            t->q1);
        if (!mod) {
          mod = TRUE;
          filemark(f);
        }
        textconstrain(t, b.q0, b.q0, &tq0, &tq1);
        up -= b.nr;
        for (i = 0; i < b.nr; i += n) {
          n = b.nr - i;
          if (n > RBUFSIZE)
            n = RBUFSIZE;
          bufread(log, up + i, buf, n);
          textinsert(t, tq0 + i, buf, n, TRUE);
        }
        if (t->q0 == b.q0 && t->q1 == b.q0)
          t->q1 += b.nr;
        break;

        /*		case Filename:
              f->seq = u.seq;
              fileunsetname(f, epsilon);
              f->mod = u.mod;
              up -= u.n;
              free(f->name);
              if(u.n == 0)
                f->name = nil;
              else
                f->name = runemalloc(u.n);
              bufread(delta, up, f->name, u.n);
              f->nname = u.n;
              break;
        */
    }
    bufdelete(log, up, log->nc);
  }
  fbuffree(buf);
  elogterm(f);

  /*
   * Bad addresses will cause bufload to crash, so double check.
   * If changes were out of order, we expect problems so don't complain further.
   */
  if (t->q0 > f->b.nc || t->q1 > f->b.nc || t->q0 > t->q1) {
    if (!warned)
      warning(nil, "elogapply: can't happen %d %d %d\n", t->q0, t->q1, f->b.nc);
    t->q1 = min(t->q1, f->b.nc);
    t->q0 = min(t->q0, t->q1);
  }

  if (t->w)
    t->w->owner = owner;
}