#include "git-compat-util.h"

#include "line-range.h"

#include "xdiff-interface.h"

#include "userdiff.h"

/*

 * Parse one item in the -L option

 *

 * 'begin' is applicable only to relative range anchors. Absolute anchors

 * ignore this value.

 *

 * When parsing "-L A,B", parse_loc() is called once for A and once for B.

 *

 * When parsing A, 'begin' must be a negative number, the absolute value of

 * which is the line at which relative start-of-range anchors should be

 * based. Beginning of file is represented by -1.

 *

 * When parsing B, 'begin' must be the positive line number immediately

 * following the line computed for 'A'.

 */

static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,

           void *data, long lines, long begin, long *ret)

{

  char *term;

  const char *line;

  long num;

  int reg_error;

  regex_t regexp;

  regmatch_t match[1];

  /* Allow "-L <something>,+20" to mean starting at <something>

   * for 20 lines, or "-L <something>,-5" for 5 lines ending at

   * <something>.

   */

  if (1 <= begin && (spec[0] == '+' || spec[0] == '-')) {

    num = strtol(spec + 1, &term, 10);

    if (term != spec + 1) {

      if (!ret)

        return term;

      if (num == 0)

        die("-L invalid empty range");

      if (spec[0] == '-')

        num = 0 - num;

      if (0 < num)

        *ret = begin + num - 2;

      else if (!num)

        *ret = begin;

      else

        *ret = begin + num > 0 ? begin + num : 1;

      return term;

    }

    return spec;

  }

  num = strtol(spec, &term, 10);

  if (term != spec) {

    if (ret) {

      if (num <= 0)

        die("-L invalid line number: %ld", num);

      *ret = num;

    }

    return term;

  }

  if (begin < 0) {

    if (spec[0] != '^')

      begin = -begin;

    else {

      begin = 1;

      spec++;

    }

  }

  if (spec[0] != '/')

    return spec;

  /* it could be a regexp of form /.../ */

  for (term = (char *) spec + 1; *term && *term != '/'; term++) {

    if (*term == '\\')

      term++;

  }

  if (*term != '/')

    return spec;

  /* in the scan-only case we are not interested in the regex */

  if (!ret)

    return term+1;

  /* try [spec+1 .. term-1] as regexp */

  *term = 0;

  begin--; /* input is in human terms */

  line = nth_line(data, begin);

  if (!(reg_error = regcomp(&regexp, spec + 1, REG_NEWLINE)) &&

      !(reg_error = regexec(&regexp, line, 1, match, 0))) {

    const char *cp = line + match[0].rm_so;

    const char *nline;

    while (begin++ < lines) {

      nline = nth_line(data, begin);

      if (line <= cp && cp < nline)

        break;

      line = nline;

    }

    *ret = begin;

    regfree(&regexp);

    *term++ = '/';

    return term;

  }

  else {

    char errbuf[1024];

    regerror(reg_error, &regexp, errbuf, 1024);

    die("-L parameter '%s' starting at line %ld: %s",

        spec + 1, begin + 1, errbuf);

  }

}

static int match_funcname(xdemitconf_t *xecfg, const char *bol, const char *eol)

{

  if (xecfg) {

    char buf[1];

    return xecfg->find_func(bol, eol - bol, buf, 1,

          xecfg->find_func_priv) >= 0;

  }

  if (bol == eol)

    return 0;

  if (isalpha(*bol) || *bol == '_' || *bol == '$')

    return 1;

  return 0;

}

static const char *find_funcname_matching_regexp(xdemitconf_t *xecfg, const char *start,

             regex_t *regexp)

{

  int reg_error;

  regmatch_t match[1];

  while (*start) {

    const char *bol, *eol;

    reg_error = regexec(regexp, start, 1, match, 0);

    if (reg_error == REG_NOMATCH)

      return NULL;

    else if (reg_error) {

      char errbuf[1024];

      regerror(reg_error, regexp, errbuf, 1024);

      die("-L parameter: regexec() failed: %s", errbuf);

    }

    /* determine extent of line matched */

    bol = start+match[0].rm_so;

    eol = start+match[0].rm_eo;

    while (bol > start && *--bol != '\n')

      ; /* nothing */

    if (*bol == '\n')

      bol++;

    while (*eol && *eol != '\n')

      eol++;

    if (*eol == '\n')

      eol++;

    /* is it a funcname line? */

    if (match_funcname(xecfg, (char*) bol, (char*) eol))

      return bol;

    start = eol;

  }

  return NULL;

}

static const char *parse_range_funcname(

  const char *arg, nth_line_fn_t nth_line_cb,

  void *cb_data, long lines, long anchor, long *begin, long *end,

  const char *path, struct index_state *istate)

{

  char *pattern;

  const char *term;

  struct userdiff_driver *drv;

  xdemitconf_t *xecfg = NULL;

  const char *start;

  const char *p;

  int reg_error;

  regex_t regexp;

  if (*arg == '^') {

    anchor = 1;

    arg++;

  }

  assert(*arg == ':');

  term = arg+1;

  while (*term && *term != ':') {

    if (*term == '\\' && *(term+1))

      term++;

    term++;

  }

  if (term == arg+1)

    return NULL;

  if (!begin) /* skip_range_arg case */

    return term;

  pattern = xstrndup(arg+1, term-(arg+1));

  anchor--; /* input is in human terms */

  start = nth_line_cb(cb_data, anchor);

  drv = userdiff_find_by_path(istate, path);

  if (drv && drv->funcname.pattern) {

    const struct userdiff_funcname *pe = &drv->funcname;

    CALLOC_ARRAY(xecfg, 1);

    xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);

  }

  reg_error = regcomp(&regexp, pattern, REG_NEWLINE);

  if (reg_error) {

    char errbuf[1024];

    regerror(reg_error, &regexp, errbuf, 1024);

    die("-L parameter '%s': %s", pattern, errbuf);

  }

  p = find_funcname_matching_regexp(xecfg, (char*) start, &regexp);

  if (!p)

    die("-L parameter '%s' starting at line %ld: no match",

        pattern, anchor + 1);

  *begin = 0;

  while (p > nth_line_cb(cb_data, *begin))

    (*begin)++;

  if (*begin >= lines)

    die("-L parameter '%s' matches at EOF", pattern);

  *end = *begin+1;

  while (*end < lines) {

    const char *bol = nth_line_cb(cb_data, *end);

    const char *eol = nth_line_cb(cb_data, *end+1);

    if (match_funcname(xecfg, bol, eol))

      break;

    (*end)++;

  }

  regfree(&regexp);

  if (xecfg)

    xdiff_clear_find_func(xecfg);

  free(xecfg);

  free(pattern);

  /* compensate for 1-based numbering */

  (*begin)++;

  return term;

}

int parse_range_arg(const char *arg, nth_line_fn_t nth_line_cb,

        void *cb_data, long lines, long anchor,

        long *begin, long *end,

        const char *path, struct index_state *istate)

{

  *begin = *end = 0;

  if (anchor < 1)

    anchor = 1;

  if (anchor > lines)

    anchor = lines + 1;

  if (*arg == ':' || (*arg == '^' && *(arg + 1) == ':')) {

    arg = parse_range_funcname(arg, nth_line_cb, cb_data,

             lines, anchor, begin, end,

             path, istate);

    if (!arg || *arg)

      return -1;

    return 0;

  }

  arg = parse_loc(arg, nth_line_cb, cb_data, lines, -anchor, begin);

  if (*arg == ',')

    arg = parse_loc(arg + 1, nth_line_cb, cb_data, lines, *begin + 1, end);

  if (*arg)

    return -1;

  if (*begin && *end && *end < *begin) {

    SWAP(*end, *begin);

  }

  return 0;

}

const char *skip_range_arg(const char *arg, struct index_state *istate)

{

  if (*arg == ':' || (*arg == '^' && *(arg + 1) == ':'))

    return parse_range_funcname(arg, NULL, NULL,

              0, 0, NULL, NULL,

              NULL, istate);

  arg = parse_loc(arg, NULL, NULL, 0, -1, NULL);

  if (*arg == ',')

    arg = parse_loc(arg+1, NULL, NULL, 0, 0, NULL);

  return arg;

}