#include <unistd.h>

#include <stdio.h>  // rename
#undef EOF          // used as a label

#include "buffer.h"
#include "case.h"
#include "cdbmake.h"
#include "logmsg.h"
#include "open.h"
#include "stralloc.h"

#define WHO "setforward"

static void usage()
{
  logmsg(WHO, 100, USAGE, "setforward data.cdb data.tmp");
}

static void nomem()
{
  logmsg(WHO, 111, FATAL, "out of memory");
}

static void missingsemicolon()
{
  logmsg(WHO, 100, FATAL, "final instruction must end with semicolon");
}

static void extracolon()
{
  logmsg(WHO, 100, FATAL, "double colons are not permitted");
}

static void extracomma()
{
  logmsg(WHO, 100, FATAL, "commas are not permitted before colons");
}

static void nulbyte()
{
  logmsg(WHO, 100, FATAL, "NUL bytes are not permitted");
}

static void longaddress()
{
  logmsg(WHO, 100, FATAL, "addresses over 800 bytes are not permitted");
}

char *fncdb;
char *fntmp;
int fd;
struct cdb_make cdb;
stralloc key = {0};

stralloc target = {0};  /* always initialized; no NUL */
stralloc command = {0}; /* always initialized; no NUL */
stralloc instr = {0};   /* always initialized */

int flagtarget = 0;
/* 0: reading target; command is empty; instr is empty */
/* 1: target is complete; instr still has to be written; reading command */

static void writeerr()
{
  logmsg(WHO, 111, FATAL, B("unable to write to: ", fntmp));
}

static void doit(char *prepend, char *data, int datalen)
{
  if (!stralloc_copys(&key, prepend)) nomem();
  if (!stralloc_cat(&key, &target)) nomem();
  case_lowerb(key.s, key.len);
  if (cdb_make_add(&cdb, key.s, key.len, data, datalen) == -1) writeerr();
}

static int getch(char *ch)
{
  int r;

  r = buffer_get(buffer_0small, ch, 1);
  if (r == -1) logmsg(WHO, 111, FATAL, "unable to read input: ");
  return r;
}

int main(int argc, char **argv)
{
  char ch;

  if (!stralloc_copys(&target, "")) nomem();
  if (!stralloc_copys(&command, "")) nomem();
  if (!stralloc_copys(&instr, "")) nomem();

  fncdb = argv[1];
  if (!fncdb) usage();
  fntmp = argv[2];
  if (!fntmp) usage();

  fd = open_trunc(fntmp);
  if (fd == -1) logmsg(WHO, 111, FATAL, B("unable to create: ", fntmp));

  if (cdb_make_start(&cdb, fd) == -1) writeerr();

  for (;;) {
    if (!getch(&ch)) goto EOF;

    if (ch == '#') {
      while (ch != '\n')
        if (!getch(&ch)) goto EOF;
      continue;
    }

    if (ch == ' ') continue;
    if (ch == '\n') continue;
    if (ch == '\t') continue;

    if (ch == ':') {
      if (flagtarget) extracolon();
      flagtarget = 1;
      continue;
    }

    if ((ch == ',') || (ch == ';')) {
      if (!flagtarget) extracomma();
      if (command.len) {
        if (command.s[0] == '?') {
          doit("?", command.s + 1, command.len - 1);
        } else if ((command.s[0] == '|') || (command.s[0] == '!')) {
          if (!stralloc_cat(&instr, &command)) nomem();
          if (!stralloc_0(&instr)) nomem();
        } else if ((command.s[0] == '.') || (command.s[0] == '/')) {
          if (!stralloc_cat(&instr, &command)) nomem();
          if (!stralloc_0(&instr)) nomem();
        } else {
          if (command.len > 800) longaddress();
          if (command.s[0] != '&')
            if (!stralloc_cats(&instr, "&")) nomem();
          if (!stralloc_cat(&instr, &command)) nomem();
          if (!stralloc_0(&instr)) nomem();
        }
      }

      if (!stralloc_copys(&command, "")) nomem();

      if (ch == ';') {
        if (instr.len) doit(":", instr.s, instr.len);

        if (!stralloc_copys(&target, "")) nomem();
        if (!stralloc_copys(&instr, "")) nomem();
        flagtarget = 0;
      }
      continue;
    }

    if (ch == '\\')
      if (!getch(&ch)) goto EOF;
    if (ch == 0) nulbyte();
    if (!stralloc_append(flagtarget ? &command : &target, &ch)) nomem();
  }

EOF:
  if (flagtarget || target.len) missingsemicolon();

  if (cdb_make_finish(&cdb) == -1) writeerr();
  if (fsync(fd) == -1) writeerr();
  if (close(fd) == -1) writeerr(); /* NFS stupidity */

  if (rename(fntmp, fncdb) == -1) logmsg(WHO, 111, FATAL, B("unable to move ", fntmp, " to: ", fncdb));

  _exit(0);
}