/* vi: set sw=4 ts=4: */
/*
 * SuS3 compliant sort implementation for busybox
 *
 * Copyright (C) 2004 by Rob Landley <rob@landley.net>
 *
 * MAINTAINER: Rob Landley <rob@landley.net>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * See SuS3 sort standard at:
 * http://www.opengroup.org/onlinepubs/007904975/utilities/sort.html
 */
//config:config SORT
//config:       bool "sort (7.4 kb)"
//config:       default y
//config:       help
//config:       sort is used to sort lines of text in specified files.
//config:
//config:config FEATURE_SORT_BIG
//config:       bool "Full SuSv3 compliant sort (support -ktcbdfiogM)"
//config:       default y
//config:       depends on SORT
//config:       help
//config:       Without this, sort only supports -rusz, and an integer version
//config:       of -n. Selecting this adds sort keys, floating point support, and
//config:       more. This adds a little over 3k to a nonstatic build on x86.
//config:
//config:       The SuSv3 sort standard is available at:
//config:       http://www.opengroup.org/onlinepubs/007904975/utilities/sort.html
//config:
//config:config FEATURE_SORT_OPTIMIZE_MEMORY
//config:       bool "Use less memory (but might be slower)"
//config:       default n   # defaults to N since we are size-paranoid tribe
//config:       depends on SORT
//config:       help
//config:       Attempt to use less memory (by storing only one copy
//config:       of duplicated lines, and such). Useful if you work on huge files.

//applet:IF_SORT(APPLET_NOEXEC(sort, sort, BB_DIR_USR_BIN, BB_SUID_DROP, sort))

//kbuild:lib-$(CONFIG_SORT) += sort.o

//usage:#define sort_trivial_usage
//usage:       "[-nru"
//usage:        IF_FEATURE_SORT_BIG("gMcszbdfiokt] [-o FILE] [-k start[.offset][opts][,end[.offset][opts]] [-t CHAR")
//usage:       "] [FILE]..."
//usage:#define sort_full_usage "\n\n"
//usage:       "Sort lines of text\n"
//usage:        IF_FEATURE_SORT_BIG(
//usage:     "\n        -o FILE Output to FILE"
//usage:     "\n        -c      Check whether input is sorted"
//usage:     "\n        -b      Ignore leading blanks"
//usage:     "\n        -f      Ignore case"
//usage:     "\n        -i      Ignore unprintable characters"
//usage:     "\n        -d      Dictionary order (blank or alphanumeric only)"
//usage:        )
//-h, --human-numeric-sort: compare human readable numbers (e.g., 2K 1G)
//usage:     "\n        -n      Sort numbers"
//usage:        IF_FEATURE_SORT_BIG(
//usage:     "\n        -g      General numerical sort"
//usage:     "\n        -M      Sort month"
//usage:     "\n        -t CHAR Field separator"
//usage:     "\n        -k N[,M] Sort by Nth field"
//usage:        )
//usage:     "\n        -r      Reverse sort order"
//usage:     "\n        -s      Stable (don't sort ties alphabetically)"
//usage:     "\n        -u      Suppress duplicate lines"
//usage:     "\n        -z      Lines are terminated by NUL, not newline"
///////:     "\n        -m      Ignored for GNU compatibility"
///////:     "\n        -S BUFSZ Ignored for GNU compatibility"
///////:     "\n        -T TMPDIR Ignored for GNU compatibility"
//usage:
//usage:#define sort_example_usage
//usage:       "$ echo -e \"e\\nf\\nb\\nd\\nc\\na\" | sort\n"
//usage:       "a\n"
//usage:       "b\n"
//usage:       "c\n"
//usage:       "d\n"
//usage:       "e\n"
//usage:       "f\n"
//usage:        IF_FEATURE_SORT_BIG(
//usage:                "$ echo -e \"c 3\\nb 2\\nd 2\" | $SORT -k 2,2n -k 1,1r\n"
//usage:                "d 2\n"
//usage:                "b 2\n"
//usage:                "c 3\n"
//usage:        )
//usage:       ""

#include "libbb.h"

/* These are sort types */
enum {
        FLAG_n  = 1,            /* Numeric sort */
        FLAG_g  = 2,            /* Sort using strtod() */
        FLAG_M  = 4,            /* Sort date */
/* ucsz apply to root level only, not keys.  b at root level implies bb */
        FLAG_u  = 8,            /* Unique */
        FLAG_c  = 0x10,         /* Check: no output, exit(!ordered) */
        FLAG_s  = 0x20,         /* Stable sort, no ascii fallback at end */
        FLAG_z  = 0x40,         /* Input and output is NUL terminated, not \n */
/* These can be applied to search keys, the previous four can't */
        FLAG_b  = 0x80,         /* Ignore leading blanks */
        FLAG_r  = 0x100,        /* Reverse */
        FLAG_d  = 0x200,        /* Ignore !(isalnum()|isspace()) */
        FLAG_f  = 0x400,        /* Force uppercase */
        FLAG_i  = 0x800,        /* Ignore !isprint() */
        FLAG_m  = 0x1000,       /* ignored: merge already sorted files; do not sort */
        FLAG_S  = 0x2000,       /* ignored: -S, --buffer-size=SIZE */
        FLAG_T  = 0x4000,       /* ignored: -T, --temporary-directory=DIR */
        FLAG_o  = 0x8000,
        FLAG_k  = 0x10000,
        FLAG_t  = 0x20000,
        FLAG_bb = 0x80000000,   /* Ignore trailing blanks  */
        FLAG_no_tie_break = 0x40000000,
};

static const char sort_opt_str[] ALIGN1 = "^"
                        "ngMucszbrdfimS:T:o:k:*t:"
                        "\0" "o--o:t--t"/*-t, -o: at most one of each*/;
/*
 * OPT_STR must not be string literal, needs to have stable address:
 * code uses "strchr(OPT_STR,c) - OPT_STR" idiom.
 */
#define OPT_STR (sort_opt_str + 1)

#if ENABLE_FEATURE_SORT_BIG
static char key_separator;

static struct sort_key {
        struct sort_key *next_key;  /* linked list */
        unsigned range[4];          /* start word, start char, end word, end char */
        unsigned flags;
} *key_list;


/* This is a NOEXEC applet. Be very careful! */


static char *get_key(char *str, struct sort_key *key, int flags)
{
        int start = start; /* for compiler */
        int end;
        int len, j;
        unsigned i;

        /* Special case whole string, so we don't have to make a copy */
        if (key->range[0] == 1 && !key->range[1] && !key->range[2] && !key->range[3]
         && !(flags & (FLAG_b | FLAG_d | FLAG_f | FLAG_i | FLAG_bb))
        ) {
                return str;
        }

        /* Find start of key on first pass, end on second pass */
        len = strlen(str);
        for (j = 0; j < 2; j++) {
                if (!key->range[2*j])
                        end = len;
                /* Loop through fields */
                else {
                        unsigned char ch = 0;

                        end = 0;
                        for (i = 1; i < key->range[2*j] + j; i++) {
                                if (key_separator) {
                                        /* Skip body of key and separator */
                                        while ((ch = str[end]) != '\0') {
                                                        end++;
                                                if (ch == key_separator)
                                                        break;
                                        }
                                } else {
                                        /* Skip leading blanks */
                                        while (isspace(str[end]))
                                                end++;
                                        /* Skip body of key */
                                        while (str[end] != '\0') {
                                                if (isspace(str[end]))
                                                        break;
                                                end++;
                                        }
                                }
                        }
                        /* Remove last delim: "abc:def:" => "abc:def" */
                        if (j && ch) {
                                //if (str[end-1] != key_separator)
                                //  bb_error_msg(_and_die("BUG! "
                                //  "str[start:%d,end:%d]:'%.*s'",
                                //  start, end, (int)(end-start), &str[start]);
                                end--;
                        }
                }
                if (!j) start = end;
        }
        /* Strip leading whitespace if necessary */
        if (flags & FLAG_b)
                /* not using skip_whitespace() for speed */
                while (isspace(str[start])) start++;
        /* Strip trailing whitespace if necessary */
        if (flags & FLAG_bb)
                while (end > start && isspace(str[end-1])) end--;
        /* -kSTART,N.ENDCHAR: honor ENDCHAR (1-based) */
        if (key->range[3]) {
                end = key->range[3];
                if (end > len) end = len;
        }
        /* -kN.STARTCHAR[,...]: honor STARTCHAR (1-based) */
        if (key->range[1]) {
                start += key->range[1] - 1;
                if (start > len) start = len;
        }
        /* Make the copy */
        if (end < start)
                end = start;
        str = xstrndup(str+start, end-start);
        /* Handle -d */
        if (flags & FLAG_d) {
                for (start = end = 0; str[end]; end++)
                        if (isspace(str[end]) || isalnum(str[end]))
                                str[start++] = str[end];
                str[start] = '\0';
        }
        /* Handle -i */
        if (flags & FLAG_i) {
                for (start = end = 0; str[end]; end++)
                        if (isprint_asciionly(str[end]))
                                str[start++] = str[end];
                str[start] = '\0';
        }
        /* Handle -f */
        if (flags & FLAG_f)
                for (i = 0; str[i]; i++)
                        str[i] = toupper(str[i]);

        return str;
}

static struct sort_key *add_key(void)
{
        struct sort_key **pkey = &key_list;
        while (*pkey)
                pkey = &((*pkey)->next_key);
        return *pkey = xzalloc(sizeof(struct sort_key));
}

#define GET_LINE(fp) \
        ((option_mask32 & FLAG_z) \
        ? bb_get_chunk_from_file(fp, NULL) \
        : xmalloc_fgetline(fp))
#else
#define GET_LINE(fp) xmalloc_fgetline(fp)
#endif

/* Iterate through keys list and perform comparisons */
static int compare_keys(const void *xarg, const void *yarg)
{
        int flags = option_mask32, retval = 0;
        char *x, *y;

#if ENABLE_FEATURE_SORT_BIG
        struct sort_key *key;

        for (key = key_list; !retval && key; key = key->next_key) {
                flags = key->flags ? key->flags : option_mask32;
                /* Chop out and modify key chunks, handling -dfib */
                x = get_key(*(char **)xarg, key, flags);
                y = get_key(*(char **)yarg, key, flags);
#else
        /* This curly bracket serves no purpose but to match the nesting
         * level of the for () loop we're not using */
        {
                x = *(char **)xarg;
                y = *(char **)yarg;
#endif
                /* Perform actual comparison */
                switch (flags & (FLAG_n | FLAG_M | FLAG_g)) {
                default:
                        bb_error_msg_and_die("unknown sort type");
                        break;
                /* Ascii sort */
                case 0:
#if ENABLE_LOCALE_SUPPORT
                        retval = strcoll(x, y);
#else
                        retval = strcmp(x, y);
#endif
                        break;
#if ENABLE_FEATURE_SORT_BIG
                case FLAG_g: {
                        char *xx, *yy;
                        double dx = strtod(x, &xx);
                        double dy = strtod(y, &yy);
                        /* not numbers < NaN < -infinity < numbers < +infinity) */
                        if (x == xx)
                                retval = (y == yy ? 0 : -1);
                        else if (y == yy)
                                retval = 1;
                        /* Check for isnan */
                        else if (dx != dx)
                                retval = (dy != dy) ? 0 : -1;
                        else if (dy != dy)
                                retval = 1;
                        /* Check for infinity.  Could underflow, but it avoids libm. */
                        else if (1.0 / dx == 0.0) {
                                if (dx < 0)
                                        retval = (1.0 / dy == 0.0 && dy < 0) ? 0 : -1;
                                else
                                        retval = (1.0 / dy == 0.0 && dy > 0) ? 0 : 1;
                        } else if (1.0 / dy == 0.0)
                                retval = (dy < 0) ? 1 : -1;
                        else
                                retval = (dx > dy) ? 1 : ((dx < dy) ? -1 : 0);
                        break;
                }
                case FLAG_M: {
                        struct tm thyme;
                        int dx;
                        char *xx, *yy;

                        xx = strptime(x, "%b", &thyme);
                        dx = thyme.tm_mon;
                        yy = strptime(y, "%b", &thyme);
                        if (!xx)
                                retval = (!yy) ? 0 : -1;
                        else if (!yy)
                                retval = 1;
                        else
                                retval = dx - thyme.tm_mon;
                        break;
                }
                /* Full floating point version of -n */
                case FLAG_n: {
                        double dx = atof(x);
                        double dy = atof(y);
                        retval = (dx > dy) ? 1 : ((dx < dy) ? -1 : 0);
                        break;
                }
                } /* switch */
                /* Free key copies. */
                if (x != *(char **)xarg) free(x);
                if (y != *(char **)yarg) free(y);
                /* if (retval) break; - done by for () anyway */
#else
                /* Integer version of -n for tiny systems */
                case FLAG_n:
                        retval = atoi(x) - atoi(y);
                        break;
                } /* switch */
#endif
        } /* for */

        if (retval == 0) {
                /* So far lines are "the same" */

                if (option_mask32 & FLAG_s) {
                        /* "Stable sort": later line is "greater than",
                         * IOW: do not allow qsort() to swap equal lines.
                         */
                        uint32_t *p32;
                        uint32_t x32, y32;
                        char *line;
                        unsigned len;

                        line = *(char**)xarg;
                        len = (strlen(line) + 4) & (~3u);
                        p32 = (void*)(line + len);
                        x32 = *p32;
                        line = *(char**)yarg;
                        len = (strlen(line) + 4) & (~3u);
                        p32 = (void*)(line + len);
                        y32 = *p32;

                        /* If x > y, 1, else -1 */
                        retval = (x32 > y32) * 2 - 1;
                } else
                if (!(option_mask32 & FLAG_no_tie_break)) {
                        /* fallback sort */
                        flags = option_mask32;
                        retval = strcmp(*(char **)xarg, *(char **)yarg);
                }
        }

        if (flags & FLAG_r)
                return -retval;

        return retval;
}

#if ENABLE_FEATURE_SORT_BIG
static unsigned str2u(char **str)
{
        unsigned long lu;
        if (!isdigit((*str)[0]))
                bb_error_msg_and_die("bad field specification");
        lu = strtoul(*str, str, 10);
        if ((sizeof(long) > sizeof(int) && lu > INT_MAX) || !lu)
                bb_error_msg_and_die("bad field specification");
        return lu;
}
#endif

int sort_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sort_main(int argc UNUSED_PARAM, char **argv)
{
        char **lines;
        char *str_ignored, *str_o, *str_t;
        llist_t *lst_k = NULL;
        int i;
        int linecount;
        unsigned opts;
#if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
        bool can_drop_dups;
        size_t prev_len = 0;
        char *prev_line = (char*) "";
        /* Postpone optimizing if the input is small, < 16k lines:
         * even just free()ing duplicate lines takes time.
         */
        size_t count_to_optimize_dups = 0x3fff;
#endif

        xfunc_error_retval = 2;

        /* Parse command line options */
        opts = getopt32(argv,
                        sort_opt_str,
                        &str_ignored, &str_ignored, &str_o, &lst_k, &str_t
        );
#if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
        /* Can drop dups only if -u but no "complicating" options,
         * IOW: if we do a full line compares. Safe options:
         * -o FILE Output to FILE
         * -z      Lines are terminated by NUL, not newline
         * -r      Reverse sort order
         * -s      Stable (don't sort ties alphabetically)
         * Not sure about these:
         * -b      Ignore leading blanks
         * -f      Ignore case
         * -i      Ignore unprintable characters
         * -d      Dictionary order (blank or alphanumeric only)
         * -n      Sort numbers
         * -g      General numerical sort
         * -M      Sort month
         */
        can_drop_dups = ((opts & ~(FLAG_o|FLAG_z|FLAG_r|FLAG_s)) == FLAG_u);
        /* Stable sort needs every line to be uniquely allocated,
         * disable optimization to reuse strings:
         */
        if (opts & FLAG_s)
                count_to_optimize_dups = (size_t)-1L;
#endif
        /* global b strips leading and trailing spaces */
        if (opts & FLAG_b)
                option_mask32 |= FLAG_bb;
#if ENABLE_FEATURE_SORT_BIG
        if (opts & FLAG_t) {
                if (!str_t[0] || str_t[1])
                        bb_error_msg_and_die("bad -t parameter");
                key_separator = str_t[0];
        }
        /* note: below this point we use option_mask32, not opts,
         * since that reduces register pressure and makes code smaller */

        /* Parse sort key */
        while (lst_k) {
                enum {
                        FLAG_allowed_for_k =
                                FLAG_n | /* Numeric sort */
                                FLAG_g | /* Sort using strtod() */
                                FLAG_M | /* Sort date */
                                FLAG_b | /* Ignore leading blanks */
                                FLAG_r | /* Reverse */
                                FLAG_d | /* Ignore !(isalnum()|isspace()) */
                                FLAG_f | /* Force uppercase */
                                FLAG_i | /* Ignore !isprint() */
                        0
                };
                struct sort_key *key = add_key();
                char *str_k = llist_pop(&lst_k);

                i = 0; /* i==0 before comma, 1 after (-k3,6) */
                while (*str_k) {
                        /* Start of range */
                        /* Cannot use bb_strtou - suffix can be a letter */
                        key->range[2*i] = str2u(&str_k);
                        if (*str_k == '.') {
                                str_k++;
                                key->range[2*i+1] = str2u(&str_k);
                        }
                        while (*str_k) {
                                int flag;
                                const char *idx;

                                if (*str_k == ',' && !i++) {
                                        str_k++;
                                        break;
                                } /* no else needed: fall through to syntax error
                                        because comma isn't in OPT_STR */
                                idx = strchr(OPT_STR, *str_k);
                                if (!idx)
                                        bb_error_msg_and_die("unknown key option");
                                flag = 1 << (idx - OPT_STR);
                                if (flag & ~FLAG_allowed_for_k)
                                        bb_error_msg_and_die("unknown sort type");
                                /* b after ',' means strip _trailing_ space */
                                if (i && flag == FLAG_b)
                                        flag = FLAG_bb;
                                key->flags |= flag;
                                str_k++;
                        }
                }
        }
#endif

        /* Open input files and read data */
        argv += optind;
        if (!*argv)
                *--argv = (char*)"-";
        linecount = 0;
        lines = NULL;
        do {
                /* coreutils 6.9 compat: abort on first open error,
                 * do not continue to next file: */
                FILE *fp = xfopen_stdin(*argv);
                for (;;) {
                        char *line = GET_LINE(fp);
                        if (!line)
                                break;

#if ENABLE_FEATURE_SORT_OPTIMIZE_MEMORY
                        if (count_to_optimize_dups != 0)
                                count_to_optimize_dups--;
                        if (count_to_optimize_dups == 0) {
                                size_t len;
                                char *new_line;

                                /* On kernel/linux/arch/ *.[ch] files,
                                 * this reduces memory usage by 6%.
                                 *  yes | head -99999999 | sort
                                 * goes down from 1900Mb to 380 Mb.
                                 */
                                len = strlen(line);
                                if (len <= prev_len) {
                                        new_line = prev_line + (prev_len - len);
                                        if (strcmp(line, new_line) == 0) {
                                                /* it's a tail of the prev line */
                                                if (can_drop_dups && prev_len == len) {
                                                        /* it's identical to prev line */
                                                        free(line);
                                                        continue;
                                                }
                                                free(line);
                                                line = new_line;
                                                /* continue using longer prev_line
                                                 * for future tail tests.
                                                 */
                                                goto skip;
                                        }
                                }
                                prev_len = len;
                                prev_line = line;
 skip: ;
                        }
#else
//TODO: lighter version which only drops total dups if can_drop_dups == true
#endif
                        lines = xrealloc_vector(lines, 6, linecount);
                        lines[linecount++] = line;
                }
                fclose_if_not_stdin(fp);
        } while (*++argv);

#if ENABLE_FEATURE_SORT_BIG
        /* If no key, perform alphabetic sort */
        if (!key_list)
                add_key()->range[0] = 1;
        /* Handle -c */
        if (option_mask32 & FLAG_c) {
                int j = (option_mask32 & FLAG_u) ? -1 : 0;
                for (i = 1; i < linecount; i++) {
                        if (compare_keys(&lines[i-1], &lines[i]) > j) {
                                fprintf(stderr, "Check line %u\n", i);
                                return EXIT_FAILURE;
                        }
                }
                return EXIT_SUCCESS;
        }
#endif

        /* For stable sort, store original line position beyond terminating NUL */
        if (option_mask32 & FLAG_s) {
                for (i = 0; i < linecount; i++) {
                        uint32_t *p32;
                        char *line;
                        unsigned len;

                        line = lines[i];
                        len = (strlen(line) + 4) & (~3u);
                        lines[i] = line = xrealloc(line, len + 4);
                        p32 = (void*)(line + len);
                        *p32 = i;
                }
                /*option_mask32 |= FLAG_no_tie_break;*/
                /* ^^^redundant: if FLAG_s, compare_keys() does no tie break */
        }

        /* Perform the actual sort */
        qsort(lines, linecount, sizeof(lines[0]), compare_keys);

        /* Handle -u */
        if (option_mask32 & FLAG_u) {
                int j = 0;
                /* coreutils 6.3 drop lines for which only key is the same
                 * -- disabling last-resort compare, or else compare_keys()
                 * will be the same only for completely identical lines.
                 */
                option_mask32 |= FLAG_no_tie_break;
                for (i = 1; i < linecount; i++) {
                        if (compare_keys(&lines[j], &lines[i]) == 0)
                                free(lines[i]);
                        else
                                lines[++j] = lines[i];
                }
                if (linecount)
                        linecount = j+1;
        }

        /* Print it */
#if ENABLE_FEATURE_SORT_BIG
        /* Open output file _after_ we read all input ones */
        if (option_mask32 & FLAG_o)
                xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), STDOUT_FILENO);
#endif
        {
                int ch = (option_mask32 & FLAG_z) ? '\0' : '\n';
                for (i = 0; i < linecount; i++)
                        printf("%s%c", lines[i], ch);
        }

        fflush_stdout_and_exit(EXIT_SUCCESS);
}