/*
 * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

#include <Windows.h>
#include <stdbool.h>
#include <io.h>
#include <stdio.h>
#include <string.h>
#include <malloc.h>

void report_error(char const * msg)
{
  LPVOID lpMsgBuf;
  DWORD dw = GetLastError();

  FormatMessage(
      FORMAT_MESSAGE_ALLOCATE_BUFFER |
      FORMAT_MESSAGE_FROM_SYSTEM |
      FORMAT_MESSAGE_IGNORE_INSERTS,
      NULL,
      dw,
      MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
      (LPTSTR) &lpMsgBuf,
      0,
      NULL);

  fprintf(stderr,
          "%s  Failed with error %d: %s\n",
          msg, dw, lpMsgBuf);

  LocalFree(lpMsgBuf);
}

/*
 * Test if pos points to /prefix/_/ where _ can
 * be any character.
 */
int is_prefix_here(int pos, char const *in, int len, const char* prefix)
{
  // Length of c/ is 2
  int prefix_size = strlen(prefix);
  if (pos+prefix_size+2 > len) return 0;
  if (in[pos+prefix_size+1]=='/') {
    return strncmp(in + pos, prefix, prefix_size) == 0;
  }
  return 0;
}

/*
 * Replace /cygdrive/_/ with _:/
 * Works in place since drive letter is always
 * shorter than /cygdrive/
 */
char *replace_cygdrive_cygwin(char const *in)
{
  size_t len = strlen(in);
  char *out = (char*) malloc(len+1);
  int i,j;

  if (len < 12) {
    memmove(out, in, len + 1);
    return out;
  }

  for (i = 0, j = 0; i<len;) {
    if (is_prefix_here(i, in, len, "/cygdrive/")) {
      out[j++] = in[i+10];
      out[j++] = ':';
      i+=11;
    } else {
      out[j] = in[i];
      i++;
      j++;
    }
  }
  out[j] = '\0';
  return out;
}

void append(char **b, size_t *bl, size_t *u, char *add, size_t addlen)
{
  while ((addlen+*u+1) > *bl) {
    *bl *= 2;
    *b = (char*) realloc(*b, *bl);
  }
  memcpy(*b+*u, add, addlen);
  *u += addlen;
}

/*
 * Creates a new string from in where the first occurrence of sub is
 * replaced by rep.
 */
char *replace_substring(char *in, char *sub, char *rep)
{
  int in_len = strlen(in);
  int sub_len = strlen(sub);
  int rep_len = strlen(rep);
  char *out = (char *) malloc(in_len - sub_len + rep_len + 1);
  char *p;

  if (!(p = strstr(in, sub))) {
    // If sub isn't a substring of in, just return in.
    return in;
  }

  // Copy characters from beginning of in to start of sub.
  strncpy(out, in, p - in);
  out[p - in] = '\0';

  sprintf(out + (p - in), "%s%s", rep, p + sub_len);

  return out;
}

char* msys_path_list; // @-separated list of paths prefix to look for
char* msys_path_list_end; // Points to last \0 in msys_path_list.

void setup_msys_path_list(char const * argument)
{
  char* p;
  char* drive_letter_pos;

  msys_path_list = strdup(&argument[2]);
  msys_path_list_end = &msys_path_list[strlen(msys_path_list)];

  // Convert all at-sign (@) in path list to \0.
  // @ was chosen as separator to minimize risk of other tools messing around with it
  p = msys_path_list;
  do {
    if (p[1] == ':') {
      // msys has mangled our path list, restore it from c:/... to /c/...
      drive_letter_pos = p+1;
      *drive_letter_pos = *p;
      *p = '/';
    }

    // Look for an @ in the list
    p = strchr(p, '@');
    if (p != NULL) {
      *p = '\0';
      p++;
    }
  } while (p != NULL);
}

char *replace_cygdrive_msys(char const *in)
{
  char* str;
  char* prefix;
  char* p;

  str = strdup(in);

  // For each prefix in the path list, search for it and replace /c/... with c:/...
  for (prefix = msys_path_list; prefix < msys_path_list_end && prefix != NULL; prefix += strlen(prefix)+1) {
    p=str;
    while ((p = strstr(p, prefix))) {
      char* drive_letter = p+1;
      *p = *drive_letter;
      *drive_letter = ':';
      p++;
    }
  }

  return str;
}

/*
 * Replace /mnt/_/ with _:/
 * Works in place since drive letter is always
 * shorter than /mnt/
 */
char *replace_cygdrive_wsl(char const *in)
{
  size_t len = strlen(in);
  char *out = (char*) malloc(len+1);
  int i,j;

  if (len < 7) {
    memmove(out, in, len + 1);
    return out;
  }

  for (i = 0, j = 0; i<len;) {
    if (is_prefix_here(i, in, len, "/mnt/")) {
      out[j++] = in[i+5];
      out[j++] = ':';
      i+=6;
    } else {
      out[j] = in[i];
      i++;
      j++;
    }
  }
  out[j] = '\0';
  return out;
}

char*(*replace_cygdrive)(char const *in) = NULL;
bool debug_fixpath = false;

char *files_to_delete[1024];
int num_files_to_delete = 0;

char *fix_at_file(char const *in)
{
  char *tmpdir;
  char name[2048];
  char *atname;
  char *buffer;
  size_t buflen=65536;
  size_t used=0;
  size_t len;
  int rc;
  FILE *atout;
  FILE *atin;
  char block[2048];
  size_t blocklen;
  char *fixed;

  atin = fopen(in+1, "r");
  if (atin == NULL) {
    fprintf(stderr, "Could not read at file %s\n", in+1);
    exit(-1);
  }

  tmpdir = getenv("TEMP");
  if (tmpdir == NULL) {
#if _WIN64
    tmpdir = "c:/cygwin64/tmp";
#else
    tmpdir = "c:/cygwin/tmp";
#endif
  }
  _snprintf(name, sizeof(name), "%s\\atfile_XXXXXX", tmpdir);

  rc = _mktemp_s(name, strlen(name)+1);
  if (rc) {
    fprintf(stderr, "Could not create temporary file name for at file!\n");
    exit(-1);
  }

  atout = fopen(name, "w");
  if (atout == NULL) {
    fprintf(stderr, "Could not open temporary file for writing! %s\n", name);
    exit(-1);
  }

  buffer = (char*) malloc(buflen);
  while ((blocklen = fread(block, 1, sizeof(block), atin)) > 0) {
    append(&buffer, &buflen, &used, block, blocklen);
  }
  buffer[used] = 0;
  if (debug_fixpath) {
    fprintf(stderr, "fixpath input from @-file %s: %s\n", &in[1], buffer);
  }
  fixed = replace_cygdrive(buffer);
  if (debug_fixpath) {
    fprintf(stderr, "fixpath converted to @-file %s is: %s\n", name, fixed);
  }
  fwrite(fixed, strlen(fixed), 1, atout);
  fclose(atin);
  fclose(atout);
  free(fixed);
  free(buffer);
  files_to_delete[num_files_to_delete] = (char*) malloc(strlen(name)+1);
  strcpy(files_to_delete[num_files_to_delete], name);
  num_files_to_delete++;
  atname = (char*) malloc(strlen(name)+2);
  atname[0] = '@';
  strcpy(atname+1, name);
  return atname;
}

// given an argument, convert it to the windows command line safe quoted version
// using rules from:
// http://blogs.msdn.com/b/twistylittlepassagesallalike/archive/2011/04/23/everyone-quotes-arguments-the-wrong-way.aspx
// caller is responsible for freeing both input and output.
char * quote_arg(char const * in_arg) {
  char *quoted = NULL;
  char *current = quoted;
  int pass;

  if (strlen(in_arg) == 0) {
     // empty string? explicitly quote it.
     return _strdup("\"\"");
  }

  if (strpbrk(in_arg, " \t\n\v\r\\\"") == NULL) {
     return _strdup(in_arg);
  }

  // process the arg twice. Once to calculate the size and then to copy it.
  for (pass=1; pass<=2; pass++) {
    char const *arg = in_arg;

    // initial "
    if (pass == 2) {
      *current = '\"';
    }
    current++;

    // process string to be quoted until NUL
    do {
      int escapes = 0;

      while (*arg == '\\') {
        // count escapes.
        escapes++;
        arg++;
      }

      if (*arg == '\0') {
         // escape the escapes before final "
         escapes *= 2;
      } else if (*arg == '"') {
        // escape the escapes and the "
        escapes = escapes * 2 + 1;
      } else {
         // escapes aren't special, just echo them.
      }

      // emit some escapes
      while (escapes > 0) {
        if (pass == 2) {
          *current = '\\';
        }
        current++;
        escapes--;
      }

      // and the current char
      if (pass == 2) {
        *current = *arg;
      }
      current++;
    } while (*arg++ != '\0');

    // allocate the buffer
    if (pass == 1) {
      size_t alloc = (size_t) (current - quoted + (ptrdiff_t) 2);
      current = quoted = (char*) calloc(alloc, sizeof(char));
    }
  }

  // final " and \0
  *(current - 1) = '"';
  *current = '\0';

  return quoted;
}

int main(int argc, char const ** argv)
{
    STARTUPINFO si;
    PROCESS_INFORMATION pi;
    unsigned short rc;

    char *line;
    char *current;
    int i, cmd;
    DWORD exitCode = 0;
    DWORD processFlags = 0;
    BOOL processInheritHandles = TRUE;
    BOOL waitForChild = TRUE;
    char* fixpathPath;

    debug_fixpath = (getenv("DEBUG_FIXPATH") != NULL);

    if (argc<2 || argv[1][0] != '-' || (argv[1][1] != 'c' && argv[1][1] != 'm' && argv[1][1] != 'w')) {
        fprintf(stderr, "Usage: fixpath -c|m|w<path@path@...> [--detach] /cygdrive/c/WINDOWS/notepad.exe [/cygdrive/c/x/test.txt|@/cygdrive/c/x/atfile]\n");
        exit(0);
    }

    if (debug_fixpath) {
      char const * cmdline = GetCommandLine();
      fprintf(stderr, "fixpath input line >%s<\n", strstr(cmdline, argv[1]));
    }

    if (argv[1][1] == 'c' && argv[1][2] == '\0') {
      if (debug_fixpath) {
        fprintf(stderr, "fixpath using cygwin mode\n");
      }
      replace_cygdrive = replace_cygdrive_cygwin;
    } else if (argv[1][1] == 'm') {
      if (debug_fixpath) {
        fprintf(stderr, "fixpath using msys mode, with path list: %s\n", &argv[1][2]);
      }
      setup_msys_path_list(argv[1]);
      replace_cygdrive = replace_cygdrive_msys;
    } else if (argv[1][1] == 'w') {
      if (debug_fixpath) {
        fprintf(stderr, "fixpath using wsl mode, with path list: %s\n", &argv[1][2]);
      }
      replace_cygdrive = replace_cygdrive_wsl;
    } else {
      fprintf(stderr, "fixpath Unknown mode: %s\n", argv[1]);
      exit(-1);
    }

    if (argv[2][0] == '-') {
      if (strcmp(argv[2], "--detach") == 0) {
        if (debug_fixpath) {
          fprintf(stderr, "fixpath in detached mode\n");
        }
        processFlags |= DETACHED_PROCESS;
        processInheritHandles = FALSE;
        waitForChild = FALSE;
      } else {
        fprintf(stderr, "fixpath Unknown argument: %s\n", argv[2]);
        exit(-1);
      }
      i = 3;
    } else {
      i = 2;
    }

    // handle assignments
    while (i < argc) {
      char const * assignment = strchr(argv[i], '=');
      if (assignment != NULL && assignment != argv[i]) {
        size_t var_len = (size_t) (assignment - argv[i] + (ptrdiff_t) 1);
        char *var = (char *) calloc(var_len, sizeof(char));
        char *val = replace_cygdrive(assignment + 1);
        memmove(var, argv[i], var_len);
        var[var_len - 1] = '\0';
        strupr(var);

        if (debug_fixpath) {
          fprintf(stderr, "fixpath setting var >%s< to >%s<\n", var, val);
        }

        rc = SetEnvironmentVariable(var, val);
        if (!rc) {
          // Could not set var for some reason.  Try to report why.
          const int msg_len = 80 + var_len + strlen(val);
          char * msg = (char *) alloca(msg_len);
          _snprintf_s(msg, msg_len, _TRUNCATE, "Could not set environment variable [%s=%s]", var, val);
          report_error(msg);
          exit(1);
        }
        free(var);
        free(val);
      } else {
        // no more assignments;
        break;
      }
      i++;
    }

    // remember index of the command
    cmd = i;

    // handle command and it's args.
    while (i < argc) {
      char const *replaced = replace_cygdrive(argv[i]);
      if (replaced[0] == '@') {
        if (waitForChild == FALSE) {
          fprintf(stderr, "fixpath Cannot use @-files in detached mode: %s\n", replaced);
          exit(1);
        }
        // Found at-file! Fix it!
        replaced = fix_at_file(replaced);
      }
      argv[i] = quote_arg(replaced);
      i++;
    }

    // determine the length of the line
    line = NULL;
    // args
    for (i = cmd; i < argc; i++) {
      line += (ptrdiff_t) strlen(argv[i]);
    }
    // spaces and null
    line += (ptrdiff_t) (argc - cmd + 1);
    // allocate
    line = (char*) calloc(line - (char*) NULL, sizeof(char));

    // copy in args.
    current = line;
    for (i = cmd; i < argc; i++) {
      ptrdiff_t len = strlen(argv[i]);
      if (i != cmd) {
        *current++ = ' ';
      }
      memmove(current, argv[i], len);
      current += len;
    }
    *current = '\0';

    if (debug_fixpath) {
      fprintf(stderr, "fixpath converted line >%s<\n", line);
    }

    if (cmd == argc) {
      if (debug_fixpath) {
        fprintf(stderr, "fixpath no command provided!\n");
      }
      exit(0);
    }

    ZeroMemory(&si, sizeof(si));
    si.cb=sizeof(si);
    ZeroMemory(&pi, sizeof(pi));

    fflush(stderr);
    fflush(stdout);

    fixpathPath = calloc(32767, sizeof(char));
    rc = GetEnvironmentVariable("FIXPATH_PATH", fixpathPath, 32767);
    if (rc) {
      if (debug_fixpath) {
        fprintf(stderr, "Setting Path to FIXPATH_PATH: %s\n", fixpathPath);
      }
      rc = SetEnvironmentVariable("Path", fixpathPath);
      if (!rc) {
        // Could not set Path for some reason.  Try to report why.
        const int msg_len = 80 + strlen(fixpathPath);
        char * msg = (char *)alloca(msg_len);
        _snprintf_s(msg, msg_len, _TRUNCATE, "Could not set environment variable [Path=%s]", fixpathPath);
        report_error(msg);
        exit(1);
      }
    }

    rc = CreateProcess(NULL,
                       line,
                       0,
                       0,
                       processInheritHandles,
                       processFlags,
                       NULL,
                       NULL,
                       &si,
                       &pi);
    if (!rc) {
      // Could not start process for some reason.  Try to report why:
      report_error("Could not start process!");
      exit(126);
    }

    if (waitForChild == TRUE) {
      WaitForSingleObject(pi.hProcess, INFINITE);
      GetExitCodeProcess(pi.hProcess, &exitCode);

      if (debug_fixpath) {
        for (i=0; i<num_files_to_delete; ++i) {
          fprintf(stderr, "fixpath Not deleting temporary file %s\n",
                  files_to_delete[i]);
        }
      } else {
        for (i=0; i<num_files_to_delete; ++i) {
          remove(files_to_delete[i]);
        }
      }

      if (exitCode != 0) {
        if (debug_fixpath) {
          fprintf(stderr, "fixpath exit code %d\n",
                  exitCode);
        }
      }
    } else {
      if (debug_fixpath) {
        fprintf(stderr, "fixpath Not waiting for child process");
      }
    }

    exit(exitCode);
}