#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"

enum { None = 0, Fore = '+', Back = '-' };

enum { Char, Line };

int isaddrc(int r) {
  if (r && utfrune("0123456789+-/$.#,;?", r) != nil)
    return TRUE;
  return FALSE;
}

/*
 * quite hard: could be almost anything but white space, but we are a little
 * conservative, aiming for regular expressions of alphanumerics and no white
 * space
 */
int isregexc(int r) {
  if (r == 0)
    return FALSE;
  if (isalnum(r))
    return TRUE;
  if (utfrune("^+-.*?#,;[]()$", r) != nil)
    return TRUE;
  return FALSE;
}

// nlcounttopos starts at q0 and advances nl lines,
// being careful not to walk past the end of the text,
// and then nr chars, being careful not to walk past
// the end of the current line.
// It returns the final position.
long nlcounttopos(Text* t, long q0, long nl, long nr) {
  while (nl > 0 && q0 < t->file->b.nc) {
    if (textreadc(t, q0++) == '\n')
      nl--;
  }
  if (nl > 0)
    return q0;
  while (nr > 0 && q0 < t->file->b.nc && textreadc(t, q0) != '\n') {
    q0++;
    nr--;
  }
  return q0;
}

Range number(
  uint showerr, Text* t, Range r, int line, int dir, int size, int* evalp) {
  uint q0, q1;

  if (size == Char) {
    if (dir == Fore)
      line = r.q1 + line;
    else if (dir == Back) {
      if (r.q0 == 0 && line > 0)
        r.q0 = t->file->b.nc;
      line = r.q0 - line;
    }
    if (line < 0 || line > t->file->b.nc)
      goto Rescue;
    *evalp = TRUE;
    return range(line, line);
  }
  q0 = r.q0;
  q1 = r.q1;
  switch (dir) {
    case None:
      q0 = 0;
      q1 = 0;
    Forward:
      while (line > 0 && q1 < t->file->b.nc)
        if (textreadc(t, q1++) == '\n' || q1 == t->file->b.nc)
          if (--line > 0)
            q0 = q1;
      if (line == 1 && q1 == t->file->b.nc) // 6 goes to end of 5-line file
        break;
      if (line > 0)
        goto Rescue;
      break;
    case Fore:
      if (q1 > 0)
        while (q1 < t->file->b.nc && textreadc(t, q1 - 1) != '\n')
          q1++;
      q0 = q1;
      goto Forward;
    case Back:
      if (q0 < t->file->b.nc)
        while (q0 > 0 && textreadc(t, q0 - 1) != '\n')
          q0--;
      q1 = q0;
      while (line > 0 && q0 > 0) {
        if (textreadc(t, q0 - 1) == '\n') {
          if (--line >= 0)
            q1 = q0;
        }
        --q0;
      }
      /* :1-1 is :0 = #0, but :1-2 is an error */
      if (line > 1)
        goto Rescue;
      while (q0 > 0 && textreadc(t, q0 - 1) != '\n')
        --q0;
  }
  *evalp = TRUE;
  return range(q0, q1);

Rescue:
  if (showerr)
    warning(nil, "address out of range\n");
  *evalp = FALSE;
  return r;
}

Range regexp(
  uint showerr, Text* t, Range lim, Range r, Rune* pat, int dir, int* foundp) {
  int found;
  Rangeset sel;
  int q;

  if (pat[0] == '\0' && rxnull()) {
    if (showerr)
      warning(nil, "no previous regular expression\n");
    *foundp = FALSE;
    return r;
  }
  if (pat[0] && rxcompile(pat) == FALSE) {
    *foundp = FALSE;
    return r;
  }
  if (dir == Back)
    found = rxbexecute(t, r.q0, &sel);
  else {
    if (lim.q0 < 0)
      q = Infinity;
    else
      q = lim.q1;
    found = rxexecute(t, nil, r.q1, q, &sel);
  }
  if (!found && showerr)
    warning(nil, "no match for regexp\n");
  *foundp = found;
  return sel.r[0];
}

Range address(
  uint showerr, Text* t, Range lim, Range ar, void* a, uint q0, uint q1,
  int (*getc)(void*, uint), int* evalp, uint* qp) {
  int dir, size, npat;
  int prevc, c, nc, n;
  uint q;
  Rune* pat;
  Range r, nr;

  r = ar;
  q = q0;
  dir = None;
  size = Line;
  c = 0;
  while (q < q1) {
    prevc = c;
    c = (*getc)(a, q++);
    switch (c) {
      default:
        *qp = q - 1;
        return r;
      case ';':
        ar = r;
        /* fall through */
      case ',':
        if (prevc == 0) /* lhs defaults to 0 */
          r.q0 = 0;
        if (q >= q1 && t != nil && t->file != nil) /* rhs defaults to $ */
          r.q1 = t->file->b.nc;
        else {
          nr = address(showerr, t, lim, ar, a, q, q1, getc, evalp, &q);
          r.q1 = nr.q1;
        }
        *qp = q;
        return r;
      case '+':
      case '-':
        if (*evalp && (prevc == '+' || prevc == '-'))
          if ((nc = (*getc)(a, q)) != '#' && nc != '/' && nc != '?')
            r = number(showerr, t, r, 1, prevc, Line, evalp); /* do previous one
                                                               */
        dir = c;
        break;
      case '.':
      case '$':
        if (q != q0 + 1) {
          *qp = q - 1;
          return r;
        }
        if (*evalp)
          if (c == '.')
            r = ar;
          else
            r = range(t->file->b.nc, t->file->b.nc);
        if (q < q1)
          dir = Fore;
        else
          dir = None;
        break;
      case '#':
        if (q == q1 || (c = (*getc)(a, q++)) < '0' || '9' < c) {
          *qp = q - 1;
          return r;
        }
        size = Char;
        /* fall through */
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        n = c - '0';
        while (q < q1) {
          nc = (*getc)(a, q++);
          if (nc < '0' || '9' < nc) {
            q--;
            break;
          }
          n = n * 10 + (nc - '0');
        }
        if (*evalp)
          r = number(showerr, t, r, n, dir, size, evalp);
        dir = None;
        size = Line;
        break;
      case '?':
        dir = Back;
        /* fall through */
      case '/':
        npat = 0;
        pat = nil;
        while (q < q1) {
          c = (*getc)(a, q++);
          switch (c) {
            case '\n':
              --q;
              goto out;
            case '\\':
              pat = runerealloc(pat, npat + 1);
              pat[npat++] = c;
              if (q == q1)
                goto out;
              c = (*getc)(a, q++);
              break;
            case '/':
              goto out;
          }
          pat = runerealloc(pat, npat + 1);
          pat[npat++] = c;
        }
      out:
        pat = runerealloc(pat, npat + 1);
        pat[npat] = 0;
        if (*evalp)
          r = regexp(showerr, t, lim, r, pat, dir, evalp);
        free(pat);
        dir = None;
        size = Line;
        break;
    }
  }
  if (*evalp && dir != None)
    r = number(showerr, t, r, 1, dir, Line, evalp); /* do previous one */
  *qp = q;
  return r;
}