#include "cache.h"
#include "builtin.h"
#include "exec_cmd.h"
#include "help.h"

/* most GUI terminals set COLUMNS (although some don't export it) */
static int term_columns(void)
{
        char *col_string = getenv("COLUMNS");
        int n_cols;

        if (col_string && (n_cols = atoi(col_string)) > 0)
                return n_cols;

#ifdef TIOCGWINSZ
        {
                struct winsize ws;
                if (!ioctl(1, TIOCGWINSZ, &ws)) {
                        if (ws.ws_col)
                                return ws.ws_col;
                }
        }
#endif

        return 80;
}

void add_cmdname(struct cmdnames *cmds, const char *name, int len)
{
        struct cmdname *ent = xmalloc(sizeof(*ent) + len + 1);

        ent->len = len;
        memcpy(ent->name, name, len);
        ent->name[len] = 0;

        ALLOC_GROW(cmds->names, cmds->cnt + 1, cmds->alloc);
        cmds->names[cmds->cnt++] = ent;
}

static int cmdname_compare(const void *a_, const void *b_)
{
        struct cmdname *a = *(struct cmdname **)a_;
        struct cmdname *b = *(struct cmdname **)b_;
        return strcmp(a->name, b->name);
}

static void uniq(struct cmdnames *cmds)
{
        int i, j;

        if (!cmds->cnt)
                return;

        for (i = j = 1; i < cmds->cnt; i++)
                if (strcmp(cmds->names[i]->name, cmds->names[i-1]->name))
                        cmds->names[j++] = cmds->names[i];

        cmds->cnt = j;
}

void exclude_cmds(struct cmdnames *cmds, struct cmdnames *excludes)
{
        int ci, cj, ei;
        int cmp;

        ci = cj = ei = 0;
        while (ci < cmds->cnt && ei < excludes->cnt) {
                cmp = strcmp(cmds->names[ci]->name, excludes->names[ei]->name);
                if (cmp < 0)
                        cmds->names[cj++] = cmds->names[ci++];
                else if (cmp == 0)
                        ci++, ei++;
                else if (cmp > 0)
                        ei++;
        }

        while (ci < cmds->cnt)
                cmds->names[cj++] = cmds->names[ci++];

        cmds->cnt = cj;
}

static void pretty_print_string_list(struct cmdnames *cmds, int longest)
{
        int cols = 1, rows;
        int space = longest + 1; /* min 1 SP between words */
        int max_cols = term_columns() - 1; /* don't print *on* the edge */
        int i, j;

        if (space < max_cols)
                cols = max_cols / space;
        rows = (cmds->cnt + cols - 1) / cols;

        for (i = 0; i < rows; i++) {
                printf("  ");

                for (j = 0; j < cols; j++) {
                        int n = j * rows + i;
                        int size = space;
                        if (n >= cmds->cnt)
                                break;
                        if (j == cols-1 || n + rows >= cmds->cnt)
                                size = 1;
                        printf("%-*s", size, cmds->names[n]->name);
                }
                putchar('\n');
        }
}

static int is_executable(const char *name)
{
        struct stat st;

        if (stat(name, &st) || /* stat, not lstat */
            !S_ISREG(st.st_mode))
                return 0;

#ifdef __MINGW32__
        /* cannot trust the executable bit, peek into the file instead */
        char buf[3] = { 0 };
        int n;
        int fd = open(name, O_RDONLY);
        st.st_mode &= ~S_IXUSR;
        if (fd >= 0) {
                n = read(fd, buf, 2);
                if (n == 2)
                        /* DOS executables start with "MZ" */
                        if (!strcmp(buf, "#!") || !strcmp(buf, "MZ"))
                                st.st_mode |= S_IXUSR;
                close(fd);
        }
#endif
        return st.st_mode & S_IXUSR;
}

static void list_commands_in_dir(struct cmdnames *cmds,
                                         const char *path,
                                         const char *prefix)
{
        int prefix_len;
        DIR *dir = opendir(path);
        struct dirent *de;
        struct strbuf buf = STRBUF_INIT;
        int len;

        if (!dir)
                return;
        if (!prefix)
                prefix = "git-";
        prefix_len = strlen(prefix);

        strbuf_addf(&buf, "%s/", path);
        len = buf.len;

        while ((de = readdir(dir)) != NULL) {
                int entlen;

                if (prefixcmp(de->d_name, prefix))
                        continue;

                strbuf_setlen(&buf, len);
                strbuf_addstr(&buf, de->d_name);
                if (!is_executable(buf.buf))
                        continue;

                entlen = strlen(de->d_name) - prefix_len;
                if (has_extension(de->d_name, ".exe"))
                        entlen -= 4;

                add_cmdname(cmds, de->d_name + prefix_len, entlen);
        }
        closedir(dir);
        strbuf_release(&buf);
}

void load_command_list(const char *prefix,
                struct cmdnames *main_cmds,
                struct cmdnames *other_cmds)
{
        const char *env_path = getenv("PATH");
        const char *exec_path = git_exec_path();

        if (exec_path) {
                list_commands_in_dir(main_cmds, exec_path, prefix);
                qsort(main_cmds->names, main_cmds->cnt,
                      sizeof(*main_cmds->names), cmdname_compare);
                uniq(main_cmds);
        }

        if (env_path) {
                char *paths, *path, *colon;
                path = paths = xstrdup(env_path);
                while (1) {
                        if ((colon = strchr(path, PATH_SEP)))
                                *colon = 0;

                        list_commands_in_dir(other_cmds, path, prefix);

                        if (!colon)
                                break;
                        path = colon + 1;
                }
                free(paths);

                qsort(other_cmds->names, other_cmds->cnt,
                      sizeof(*other_cmds->names), cmdname_compare);
                uniq(other_cmds);
        }
        exclude_cmds(other_cmds, main_cmds);
}

void list_commands(const char *title, struct cmdnames *main_cmds,
                   struct cmdnames *other_cmds)
{
        int i, longest = 0;

        for (i = 0; i < main_cmds->cnt; i++)
                if (longest < main_cmds->names[i]->len)
                        longest = main_cmds->names[i]->len;
        for (i = 0; i < other_cmds->cnt; i++)
                if (longest < other_cmds->names[i]->len)
                        longest = other_cmds->names[i]->len;

        if (main_cmds->cnt) {
                const char *exec_path = git_exec_path();
                printf("available %s in '%s'\n", title, exec_path);
                printf("----------------");
                mput_char('-', strlen(title) + strlen(exec_path));
                putchar('\n');
                pretty_print_string_list(main_cmds, longest);
                putchar('\n');
        }

        if (other_cmds->cnt) {
                printf("%s available from elsewhere on your $PATH\n", title);
                printf("---------------------------------------");
                mput_char('-', strlen(title));
                putchar('\n');
                pretty_print_string_list(other_cmds, longest);
                putchar('\n');
        }
}

int is_in_cmdlist(struct cmdnames *c, const char *s)
{
        int i;
        for (i = 0; i < c->cnt; i++)
                if (!strcmp(s, c->names[i]->name))
                        return 1;
        return 0;
}

void help_unknown_cmd(const char *cmd)
{
        fprintf(stderr, "git: '%s' is not a git-command. See 'git --help'.\n", cmd);
        exit(1);
}

int cmd_version(int argc, const char **argv, const char *prefix)
{
        printf("git version %s\n", git_version_string);
        return 0;
}