/*

 * Copyright (C) 2005 Junio C Hamano

 * Copyright (C) 2010 Google Inc.

 */

#include "git-compat-util.h"

#include "diff.h"

#include "diffcore.h"

#include "xdiff-interface.h"

#include "kwset.h"

#include "oidset.h"

#include "pretty.h"

#include "quote.h"

typedef int (*pickaxe_fn)(mmfile_t *one, mmfile_t *two,

        struct diff_options *o,

        regex_t *regexp, kwset_t kws);

struct diffgrep_cb {

  regex_t *regexp;

  int hit;

};

static int diffgrep_consume(void *priv, char *line, unsigned long len)

{

  struct diffgrep_cb *data = priv;

  regmatch_t regmatch;

  if (line[0] != '+' && line[0] != '-')

    return 0;

  if (data->hit)

    BUG("Already matched in diffgrep_consume! Broken xdiff_emit_line_fn?");

  if (!regexec_buf(data->regexp, line + 1, len - 1, 1,

       &regmatch, 0)) {

    data->hit = 1;

    return 1;

  }

  return 0;

}

static int diff_grep(mmfile_t *one, mmfile_t *two,

         struct diff_options *o,

         regex_t *regexp, kwset_t kws UNUSED)

{

  struct diffgrep_cb ecbdata;

  xpparam_t xpp;

  xdemitconf_t xecfg;

  int ret;

  /*

   * We have both sides; need to run textual diff and see if

   * the pattern appears on added/deleted lines.

   */

  memset(&xpp, 0, sizeof(xpp));

  memset(&xecfg, 0, sizeof(xecfg));

  ecbdata.regexp = regexp;

  ecbdata.hit = 0;

  xecfg.flags = XDL_EMIT_NO_HUNK_HDR;

  xecfg.ctxlen = o->context;

  xecfg.interhunkctxlen = o->interhunkcontext;

  /*

   * An xdiff error might be our "data->hit" from above. See the

   * comment for xdiff_emit_line_fn in xdiff-interface.h

   */

  ret = xdi_diff_outf(one, two, NULL, diffgrep_consume,

          &ecbdata, &xpp, &xecfg);

  if (ecbdata.hit)

    return 1;

  if (ret)

    return ret;

  return 0;

}

static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws,

           unsigned int limit)

{

  unsigned int cnt = 0;

  unsigned long sz = mf->size;

  const char *data = mf->ptr;

  if (regexp) {

    regmatch_t regmatch;

    int flags = 0;

    while (sz &&

           !regexec_buf(regexp, data, sz, 1, &regmatch, flags)) {

      flags |= REG_NOTBOL;

      data += regmatch.rm_eo;

      sz -= regmatch.rm_eo;

      if (sz && regmatch.rm_so == regmatch.rm_eo) {

        data++;

        sz--;

      }

      cnt++;

      if (limit && cnt == limit)

        return cnt;

    }

  } else { /* Classic exact string match */

    while (sz) {

      struct kwsmatch kwsm;

      size_t offset = kwsexec(kws, data, sz, &kwsm);

      if (offset == -1)

        break;

      sz -= offset + kwsm.size[0];

      data += offset + kwsm.size[0];

      cnt++;

      if (limit && cnt == limit)

        return cnt;

    }

  }

  return cnt;

}

static int has_changes(mmfile_t *one, mmfile_t *two,

           struct diff_options *o UNUSED,

           regex_t *regexp, kwset_t kws)

{

  unsigned int c1 = one ? contains(one, regexp, kws, 0) : 0;

  unsigned int c2 = two ? contains(two, regexp, kws, c1 + 1) : 0;

  return c1 != c2;

}

static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,

       regex_t *regexp, kwset_t kws, pickaxe_fn fn)

{

  struct userdiff_driver *textconv_one = NULL;

  struct userdiff_driver *textconv_two = NULL;

  mmfile_t mf1, mf2;

  int ret;

  /* ignore unmerged */

  if (!DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two))

    return 0;

  if (o->objfind) {

    return  (DIFF_FILE_VALID(p->one) &&

       oidset_contains(o->objfind, &p->one->oid)) ||

      (DIFF_FILE_VALID(p->two) &&

       oidset_contains(o->objfind, &p->two->oid));

  }

  if (o->flags.allow_textconv) {

    textconv_one = get_textconv(o->repo, p->one);

    textconv_two = get_textconv(o->repo, p->two);

  }

  /*

   * If we have an unmodified pair, we know that the count will be the

   * same and don't even have to load the blobs. Unless textconv is in

   * play, _and_ we are using two different textconv filters (e.g.,

   * because a pair is an exact rename with different textconv attributes

   * for each side, which might generate different content).

   */

  if (textconv_one == textconv_two && diff_unmodified_pair(p))

    return 0;

  if ((o->pickaxe_opts & DIFF_PICKAXE_KIND_G) &&

      !o->flags.text &&

      ((!textconv_one && diff_filespec_is_binary(o->repo, p->one)) ||

       (!textconv_two && diff_filespec_is_binary(o->repo, p->two))))

    return 0;

  mf1.size = fill_textconv(o->repo, textconv_one, p->one, &mf1.ptr);

  mf2.size = fill_textconv(o->repo, textconv_two, p->two, &mf2.ptr);

  ret = fn(&mf1, &mf2, o, regexp, kws);

  if (textconv_one)

    free(mf1.ptr);

  if (textconv_two)

    free(mf2.ptr);

  diff_free_filespec_data(p->one);

  diff_free_filespec_data(p->two);

  return ret;

}

static void pickaxe(struct diff_queue_struct *q, struct diff_options *o,

        regex_t *regexp, kwset_t kws, pickaxe_fn fn)

{

  int i;

  struct diff_queue_struct outq;

  DIFF_QUEUE_CLEAR(&outq);

  if (o->pickaxe_opts & DIFF_PICKAXE_ALL) {

    /* Showing the whole changeset if needle exists */

    for (i = 0; i < q->nr; i++) {

      struct diff_filepair *p = q->queue[i];

      if (pickaxe_match(p, o, regexp, kws, fn))

        return; /* do not munge the queue */

    }

    /*

     * Otherwise we will clear the whole queue by copying

     * the empty outq at the end of this function, but

     * first clear the current entries in the queue.

     */

    for (i = 0; i < q->nr; i++)

      diff_free_filepair(q->queue[i]);

  } else {

    /* Showing only the filepairs that has the needle */

    for (i = 0; i < q->nr; i++) {

      struct diff_filepair *p = q->queue[i];

      if (pickaxe_match(p, o, regexp, kws, fn))

        diff_q(&outq, p);

      else

        diff_free_filepair(p);

    }

  }

  free(q->queue);

  *q = outq;

}

static void regcomp_or_die(regex_t *regex, const char *needle, int cflags)

{

  int err = regcomp(regex, needle, cflags);

  if (err) {

    /* The POSIX.2 people are surely sick */

    char errbuf[1024];

    regerror(err, regex, errbuf, 1024);

    die("invalid regex: %s", errbuf);

  }

}

void diffcore_pickaxe(struct diff_options *o)

{

  const char *needle = o->pickaxe;

  int opts = o->pickaxe_opts;

  regex_t regex, *regexp = NULL;

  kwset_t kws = NULL;

  pickaxe_fn fn;

  if (opts & ~DIFF_PICKAXE_KIND_OBJFIND &&

      (!needle || !*needle))

    BUG("should have needle under -G or -S");

  if (opts & (DIFF_PICKAXE_REGEX | DIFF_PICKAXE_KIND_G)) {

    int cflags = REG_EXTENDED | REG_NEWLINE;

    if (o->pickaxe_opts & DIFF_PICKAXE_IGNORE_CASE)

      cflags |= REG_ICASE;

    regcomp_or_die(&regex, needle, cflags);

    regexp = &regex;

    if (opts & DIFF_PICKAXE_KIND_G)

      fn = diff_grep;

    else if (opts & DIFF_PICKAXE_REGEX)

      fn = has_changes;

    else

      /*

       * We don't need to check the combination of

       * -G and --pickaxe-regex, by the time we get

       * here diff.c has already died if they're

       * combined. See the usage tests in

       * t4209-log-pickaxe.sh.

       */

      BUG("unreachable");

  } else if (opts & DIFF_PICKAXE_KIND_S) {

    if (o->pickaxe_opts & DIFF_PICKAXE_IGNORE_CASE &&

        has_non_ascii(needle)) {

      struct strbuf sb = STRBUF_INIT;

      int cflags = REG_NEWLINE | REG_ICASE;

      basic_regex_quote_buf(&sb, needle);

      regcomp_or_die(&regex, sb.buf, cflags);

      strbuf_release(&sb);

      regexp = &regex;

    } else {

      kws = kwsalloc(o->pickaxe_opts & DIFF_PICKAXE_IGNORE_CASE

               ? tolower_trans_tbl : NULL);

      kwsincr(kws, needle, strlen(needle));

      kwsprep(kws);

    }

    fn = has_changes;

  } else if (opts & DIFF_PICKAXE_KIND_OBJFIND) {

    fn = NULL;

  } else {

    BUG("unknown pickaxe_opts flag");

  }

  pickaxe(&diff_queued_diff, o, regexp, kws, fn);

  if (regexp)

    regfree(regexp);

  if (kws)

    kwsfree(kws);

  return;

}