#include "cache.h"
#include "string-list.h"
#include "mailmap.h"

#define DEBUG_MAILMAP 0
#if DEBUG_MAILMAP
#define debug_mm(...) fprintf(stderr, __VA_ARGS__)
#define debug_str(X) ((X) ? (X) : "(none)")
#else
static inline void debug_mm(const char *format, ...) {}
static inline const char *debug_str(const char *s) { return s; }
#endif

const char *git_mailmap_file;
const char *git_mailmap_blob;

struct mailmap_info {
        char *name;
        char *email;
};

struct mailmap_entry {
        /* name and email for the simple mail-only case */
        char *name;
        char *email;

        /* name and email for the complex mail and name matching case */
        struct string_list namemap;
};

static void free_mailmap_info(void *p, const char *s)
{
        struct mailmap_info *mi = (struct mailmap_info *)p;
        debug_mm("mailmap: -- complex: '%s' -> '%s' <%s>\n",
                 s, debug_str(mi->name), debug_str(mi->email));
        free(mi->name);
        free(mi->email);
}

static void free_mailmap_entry(void *p, const char *s)
{
        struct mailmap_entry *me = (struct mailmap_entry *)p;
        debug_mm("mailmap: removing entries for <%s>, with %d sub-entries\n",
                 s, me->namemap.nr);
        debug_mm("mailmap: - simple: '%s' <%s>\n",
                 debug_str(me->name), debug_str(me->email));

        free(me->name);
        free(me->email);

        me->namemap.strdup_strings = 1;
        string_list_clear_func(&me->namemap, free_mailmap_info);
}

/*
 * On some systems (e.g. MinGW 4.0), string.h has _only_ inline
 * definition of strcasecmp and no non-inline implementation is
 * supplied anywhere, which is, eh, "unusual"; we cannot take an
 * address of such a function to store it in namemap.cmp.  This is
 * here as a workaround---do not assign strcasecmp directly to
 * namemap.cmp until we know no systems that matter have such an
 * "unusual" string.h.
 */
static int namemap_cmp(const char *a, const char *b)
{
        return strcasecmp(a, b);
}

static void add_mapping(struct string_list *map,
                        char *new_name, char *new_email,
                        char *old_name, char *old_email)
{
        struct mailmap_entry *me;
        struct string_list_item *item;

        if (old_email == NULL) {
                old_email = new_email;
                new_email = NULL;
        }

        item = string_list_insert(map, old_email);
        if (item->util) {
                me = (struct mailmap_entry *)item->util;
        } else {
                me = xcalloc(1, sizeof(struct mailmap_entry));
                me->namemap.strdup_strings = 1;
                me->namemap.cmp = namemap_cmp;
                item->util = me;
        }

        if (old_name == NULL) {
                debug_mm("mailmap: adding (simple) entry for '%s'\n", old_email);

                /* Replace current name and new email for simple entry */
                if (new_name) {
                        free(me->name);
                        me->name = xstrdup(new_name);
                }
                if (new_email) {
                        free(me->email);
                        me->email = xstrdup(new_email);
                }
        } else {
                struct mailmap_info *mi = xcalloc(1, sizeof(struct mailmap_info));
                debug_mm("mailmap: adding (complex) entry for '%s'\n", old_email);
                mi->name = xstrdup_or_null(new_name);
                mi->email = xstrdup_or_null(new_email);
                string_list_insert(&me->namemap, old_name)->util = mi;
        }

        debug_mm("mailmap:  '%s' <%s> -> '%s' <%s>\n",
                 debug_str(old_name), old_email,
                 debug_str(new_name), debug_str(new_email));
}

static char *parse_name_and_email(char *buffer, char **name,
                                  char **email, int allow_empty_email)
{
        char *left, *right, *nstart, *nend;
        *name = *email = NULL;

        if ((left = strchr(buffer, '<')) == NULL)
                return NULL;
        if ((right = strchr(left+1, '>')) == NULL)
                return NULL;
        if (!allow_empty_email && (left+1 == right))
                return NULL;

        /* remove whitespace from beginning and end of name */
        nstart = buffer;
        while (isspace(*nstart) && nstart < left)
                ++nstart;
        nend = left-1;
        while (nend > nstart && isspace(*nend))
                --nend;

        *name = (nstart <= nend ? nstart : NULL);
        *email = left+1;
        *(nend+1) = '\0';
        *right++ = '\0';

        return (*right == '\0' ? NULL : right);
}

static void read_mailmap_line(struct string_list *map, char *buffer,
                              char **repo_abbrev)
{
        char *name1 = NULL, *email1 = NULL, *name2 = NULL, *email2 = NULL;
        if (buffer[0] == '#') {
                static const char abbrev[] = "# repo-abbrev:";
                int abblen = sizeof(abbrev) - 1;
                int len = strlen(buffer);

                if (!repo_abbrev)
                        return;

                if (len && buffer[len - 1] == '\n')
                        buffer[--len] = 0;
                if (!strncmp(buffer, abbrev, abblen)) {
                        char *cp;

                        free(*repo_abbrev);

                        for (cp = buffer + abblen; isspace(*cp); cp++)
                                ; /* nothing */
                        *repo_abbrev = xstrdup(cp);
                }
                return;
        }
        if ((name2 = parse_name_and_email(buffer, &name1, &email1, 0)) != NULL)
                parse_name_and_email(name2, &name2, &email2, 1);

        if (email1)
                add_mapping(map, name1, email1, name2, email2);
}

static int read_mailmap_file(struct string_list *map, const char *filename,
                             char **repo_abbrev)
{
        char buffer[1024];
        FILE *f;

        if (!filename)
                return 0;

        f = fopen(filename, "r");
        if (!f) {
                if (errno == ENOENT)
                        return 0;
                return error_errno("unable to open mailmap at %s", filename);
        }

        while (fgets(buffer, sizeof(buffer), f) != NULL)
                read_mailmap_line(map, buffer, repo_abbrev);
        fclose(f);
        return 0;
}

static void read_mailmap_string(struct string_list *map, char *buf,
                                char **repo_abbrev)
{
        while (*buf) {
                char *end = strchrnul(buf, '\n');

                if (*end)
                        *end++ = '\0';

                read_mailmap_line(map, buf, repo_abbrev);
                buf = end;
        }
}

static int read_mailmap_blob(struct string_list *map,
                             const char *name,
                             char **repo_abbrev)
{
        unsigned char sha1[20];
        char *buf;
        unsigned long size;
        enum object_type type;

        if (!name)
                return 0;
        if (get_sha1(name, sha1) < 0)
                return 0;

        buf = read_sha1_file(sha1, &type, &size);
        if (!buf)
                return error("unable to read mailmap object at %s", name);
        if (type != OBJ_BLOB)
                return error("mailmap is not a blob: %s", name);

        read_mailmap_string(map, buf, repo_abbrev);

        free(buf);
        return 0;
}

int read_mailmap(struct string_list *map, char **repo_abbrev)
{
        int err = 0;

        map->strdup_strings = 1;
        map->cmp = namemap_cmp;

        if (!git_mailmap_blob && is_bare_repository())
                git_mailmap_blob = "HEAD:.mailmap";

        err |= read_mailmap_file(map, ".mailmap", repo_abbrev);
        if (startup_info->have_repository)
                err |= read_mailmap_blob(map, git_mailmap_blob, repo_abbrev);
        err |= read_mailmap_file(map, git_mailmap_file, repo_abbrev);
        return err;
}

void clear_mailmap(struct string_list *map)
{
        debug_mm("mailmap: clearing %d entries...\n", map->nr);
        map->strdup_strings = 1;
        string_list_clear_func(map, free_mailmap_entry);
        debug_mm("mailmap: cleared\n");
}

/*
 * Look for an entry in map that match string[0:len]; string[len]
 * does not have to be NUL (but it could be).
 */
static struct string_list_item *lookup_prefix(struct string_list *map,
                                              const char *string, size_t len)
{
        int i = string_list_find_insert_index(map, string, 1);
        if (i < 0) {
                /* exact match */
                i = -1 - i;
                if (!string[len])
                        return &map->items[i];
                /*
                 * that map entry matches exactly to the string, including
                 * the cruft at the end beyond "len".  That is not a match
                 * with string[0:len] that we are looking for.
                 */
        } else if (!string[len]) {
                /*
                 * asked with the whole string, and got nothing.  No
                 * matching entry can exist in the map.
                 */
                return NULL;
        }

        /*
         * i is at the exact match to an overlong key, or location the
         * overlong key would be inserted, which must come after the
         * real location of the key if one exists.
         */
        while (0 <= --i && i < map->nr) {
                int cmp = strncasecmp(map->items[i].string, string, len);
                if (cmp < 0)
                        /*
                         * "i" points at a key definitely below the prefix;
                         * the map does not have string[0:len] in it.
                         */
                        break;
                else if (!cmp && !map->items[i].string[len])
                        /* found it */
                        return &map->items[i];
                /*
                 * otherwise, the string at "i" may be string[0:len]
                 * followed by a string that sorts later than string[len:];
                 * keep trying.
                 */
        }
        return NULL;
}

int map_user(struct string_list *map,
             const char **email, size_t *emaillen,
             const char **name, size_t *namelen)
{
        struct string_list_item *item;
        struct mailmap_entry *me;

        debug_mm("map_user: map '%.*s' <%.*s>\n",
                 (int)*namelen, debug_str(*name),
                 (int)*emaillen, debug_str(*email));

        item = lookup_prefix(map, *email, *emaillen);
        if (item != NULL) {
                me = (struct mailmap_entry *)item->util;
                if (me->namemap.nr) {
                        /*
                         * The item has multiple items, so we'll look up on
                         * name too. If the name is not found, we choose the
                         * simple entry.
                         */
                        struct string_list_item *subitem;
                        subitem = lookup_prefix(&me->namemap, *name, *namelen);
                        if (subitem)
                                item = subitem;
                }
        }
        if (item != NULL) {
                struct mailmap_info *mi = (struct mailmap_info *)item->util;
                if (mi->name == NULL && mi->email == NULL) {
                        debug_mm("map_user:  -- (no simple mapping)\n");
                        return 0;
                }
                if (mi->email) {
                                *email = mi->email;
                                *emaillen = strlen(*email);
                }
                if (mi->name) {
                                *name = mi->name;
                                *namelen = strlen(*name);
                }
                debug_mm("map_user:  to '%.*s' <%.*s>\n",
                         (int)*namelen, debug_str(*name),
                         (int)*emaillen, debug_str(*email));
                return 1;
        }
        debug_mm("map_user:  --\n");
        return 0;
}