/*
 * Copyright (C) 2005 Junio C Hamano
 * Copyright (C) 2010 Google Inc.
 */
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
#include "xdiff-interface.h"
#include "kwset.h"

struct diffgrep_cb {
        regex_t *regexp;
        int hit;
};

static void diffgrep_consume(void *priv, char *line, unsigned long len)
{
        struct diffgrep_cb *data = priv;
        regmatch_t regmatch;
        int hold;

        if (line[0] != '+' && line[0] != '-')
                return;
        if (data->hit)
                /*
                 * NEEDSWORK: we should have a way to terminate the
                 * caller early.
                 */
                return;
        /* Yuck -- line ought to be "const char *"! */
        hold = line[len];
        line[len] = '\0';
        data->hit = !regexec(data->regexp, line + 1, 1, &regmatch, 0);
        line[len] = hold;
}

static void fill_one(struct diff_filespec *one,
                     mmfile_t *mf, struct userdiff_driver **textconv)
{
        if (DIFF_FILE_VALID(one)) {
                *textconv = get_textconv(one);
                mf->size = fill_textconv(*textconv, one, &mf->ptr);
        } else {
                memset(mf, 0, sizeof(*mf));
        }
}

static int diff_grep(struct diff_filepair *p, regex_t *regexp, struct diff_options *o)
{
        regmatch_t regmatch;
        struct userdiff_driver *textconv_one = NULL;
        struct userdiff_driver *textconv_two = NULL;
        mmfile_t mf1, mf2;
        int hit;

        if (diff_unmodified_pair(p))
                return 0;

        fill_one(p->one, &mf1, &textconv_one);
        fill_one(p->two, &mf2, &textconv_two);

        if (!mf1.ptr) {
                if (!mf2.ptr)
                        return 0; /* ignore unmerged */
                /* created "two" -- does it have what we are looking for? */
                hit = !regexec(regexp, p->two->data, 1, &regmatch, 0);
        } else if (!mf2.ptr) {
                /* removed "one" -- did it have what we are looking for? */
                hit = !regexec(regexp, p->one->data, 1, &regmatch, 0);
        } else {
                /*
                 * We have both sides; need to run textual diff and see if
                 * the pattern appears on added/deleted lines.
                 */
                struct diffgrep_cb ecbdata;
                xpparam_t xpp;
                xdemitconf_t xecfg;

                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                ecbdata.regexp = regexp;
                ecbdata.hit = 0;
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
                xdi_diff_outf(&mf1, &mf2, diffgrep_consume, &ecbdata,
                              &xpp, &xecfg);
                hit = ecbdata.hit;
        }
        if (textconv_one)
                free(mf1.ptr);
        if (textconv_two)
                free(mf2.ptr);
        return hit;
}

static void diffcore_pickaxe_grep(struct diff_options *o)
{
        struct diff_queue_struct *q = &diff_queued_diff;
        int i, err;
        regex_t regex;
        struct diff_queue_struct outq;
        outq.queue = NULL;
        outq.nr = outq.alloc = 0;

        err = regcomp(&regex, o->pickaxe, REG_EXTENDED | REG_NEWLINE);
        if (err) {
                char errbuf[1024];
                regerror(err, &regex, errbuf, 1024);
                regfree(&regex);
                die("invalid log-grep regex: %s", errbuf);
        }

        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 (diff_grep(p, &regex, o))
                                goto out; /* 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 (diff_grep(p, &regex, o))
                                diff_q(&outq, p);
                        else
                                diff_free_filepair(p);
                }
        }

        free(q->queue);
        *q = outq;

 out:
        regfree(&regex);
        return;
}

static unsigned int contains(struct diff_filespec *one,
                             const char *needle, unsigned long len,
                             regex_t *regexp, kwset_t kws)
{
        unsigned int cnt;
        unsigned long sz;
        const char *data;
        if (!len)
                return 0;
        if (diff_populate_filespec(one, 0))
                return 0;

        sz = one->size;
        data = one->data;
        cnt = 0;

        if (regexp) {
                regmatch_t regmatch;
                int flags = 0;

                assert(data[sz] == '\0');
                while (*data && !regexec(regexp, data, 1, &regmatch, flags)) {
                        flags |= REG_NOTBOL;
                        data += regmatch.rm_eo;
                        if (*data && regmatch.rm_so == regmatch.rm_eo)
                                data++;
                        cnt++;
                }

        } else { /* Classic exact string match */
                while (sz) {
                        size_t offset = kwsexec(kws, data, sz, NULL);
                        const char *found;
                        if (offset == -1)
                                break;
                        else
                                found = data + offset;
                        sz -= found - data + len;
                        data = found + len;
                        cnt++;
                }
        }
        diff_free_filespec_data(one);
        return cnt;
}

static void diffcore_pickaxe_count(struct diff_options *o)
{
        const char *needle = o->pickaxe;
        int opts = o->pickaxe_opts;
        struct diff_queue_struct *q = &diff_queued_diff;
        unsigned long len = strlen(needle);
        int i, has_changes;
        regex_t regex, *regexp = NULL;
        kwset_t kws = NULL;
        struct diff_queue_struct outq;
        DIFF_QUEUE_CLEAR(&outq);

        if (opts & DIFF_PICKAXE_REGEX) {
                int err;
                err = regcomp(&regex, needle, REG_EXTENDED | REG_NEWLINE);
                if (err) {
                        /* The POSIX.2 people are surely sick */
                        char errbuf[1024];
                        regerror(err, &regex, errbuf, 1024);
                        regfree(&regex);
                        die("invalid pickaxe regex: %s", errbuf);
                }
                regexp = &regex;
        } else {
                kws = kwsalloc(NULL);
                kwsincr(kws, needle, len);
                kwsprep(kws);
        }

        if (opts & DIFF_PICKAXE_ALL) {
                /* Showing the whole changeset if needle exists */
                for (i = has_changes = 0; !has_changes && i < q->nr; i++) {
                        struct diff_filepair *p = q->queue[i];
                        if (!DIFF_FILE_VALID(p->one)) {
                                if (!DIFF_FILE_VALID(p->two))
                                        continue; /* ignore unmerged */
                                /* created */
                                if (contains(p->two, needle, len, regexp, kws))
                                        has_changes++;
                        }
                        else if (!DIFF_FILE_VALID(p->two)) {
                                if (contains(p->one, needle, len, regexp, kws))
                                        has_changes++;
                        }
                        else if (!diff_unmodified_pair(p) &&
                                 contains(p->one, needle, len, regexp, kws) !=
                                 contains(p->two, needle, len, regexp, kws))
                                has_changes++;
                }
                if (has_changes)
                        return; /* 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];
                        has_changes = 0;
                        if (!DIFF_FILE_VALID(p->one)) {
                                if (!DIFF_FILE_VALID(p->two))
                                        ; /* ignore unmerged */
                                /* created */
                                else if (contains(p->two, needle, len, regexp,
                                                  kws))
                                        has_changes = 1;
                        }
                        else if (!DIFF_FILE_VALID(p->two)) {
                                if (contains(p->one, needle, len, regexp, kws))
                                        has_changes = 1;
                        }
                        else if (!diff_unmodified_pair(p) &&
                                 contains(p->one, needle, len, regexp, kws) !=
                                 contains(p->two, needle, len, regexp, kws))
                                has_changes = 1;

                        if (has_changes)
                                diff_q(&outq, p);
                        else
                                diff_free_filepair(p);
                }

        if (opts & DIFF_PICKAXE_REGEX)
                regfree(&regex);
        else
                kwsfree(kws);

        free(q->queue);
        *q = outq;
        return;
}

void diffcore_pickaxe(struct diff_options *o)
{
        /* Might want to warn when both S and G are on; I don't care... */
        if (o->pickaxe_opts & DIFF_PICKAXE_KIND_G)
                diffcore_pickaxe_grep(o);
        else
                diffcore_pickaxe_count(o);
}