/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2017 Jason King
 */
#include <string.h>
#include "str.h"
#include "demangle_int.h"

#define STR_CHUNK_SZ    (64U)

/* are we storing a reference vs. a dynamically allocated copy? */
#define IS_REF(s) ((s)->str_s != NULL && (s)->str_size == 0)

/*
 * Dynamically resizeable strings, with lazy allocation when initialized
 * with a constant string value
 *
 * NOTE: these are not necessairly 0-terminated
 *
 * Additionally, these can store references instead of copies of strings
 * (as indicated by the IS_REF() macro.  However mutation may cause a
 * string to convert from a refence to a dynamically allocated copy.
 */

void
str_init(str_t *restrict s, sysdem_ops_t *restrict ops)
{
        (void) memset(s, 0, sizeof (*s));
        s->str_ops = (ops != NULL) ? ops : sysdem_ops_default;
}

void
str_fini(str_t *s)
{
        if (s == NULL)
                return;
        if (!IS_REF(s))
                xfree(s->str_ops, s->str_s, s->str_size);
        (void) memset(s, 0, sizeof (*s));
}

size_t
str_length(const str_t *s)
{
        return (s->str_len);
}

/*
 * store as a reference instead of a copy
 * if len == 0, means store entire copy of 0 terminated string
 */
void
str_set(str_t *s, const char *cstr, size_t len)
{
        sysdem_ops_t *ops = s->str_ops;

        str_fini(s);
        s->str_ops = ops;
        s->str_s = (char *)cstr;
        s->str_len = (len == 0 && cstr != NULL) ? strlen(cstr) : len;
}

boolean_t
str_copy(const str_t *src, str_t *dest)
{
        str_fini(dest);
        str_init(dest, src->str_ops);

        if (src->str_len == 0)
                return (B_TRUE);

        size_t len = roundup(src->str_len, STR_CHUNK_SZ);
        dest->str_s = zalloc(src->str_ops, len);
        if (dest->str_s == NULL)
                return (B_FALSE);

        (void) memcpy(dest->str_s, src->str_s, src->str_len);
        dest->str_len = src->str_len;
        dest->str_size = len;

        return (B_TRUE);
}

/*
 * ensure s has at least amt bytes free, resizing if necessary
 */
static boolean_t
str_reserve(str_t *s, size_t amt)
{
        size_t newlen = s->str_len + amt;

        /* overflow check */
        if (newlen < s->str_len || newlen < amt)
                return (B_FALSE);

        if ((amt > 0) && (s->str_len + amt <= s->str_size))
                return (B_TRUE);

        size_t newsize = roundup(newlen, STR_CHUNK_SZ);
        void *temp;

        if (IS_REF(s)) {
                temp = zalloc(s->str_ops, newsize);
                if (temp == NULL)
                        return (B_FALSE);

                (void) memcpy(temp, s->str_s, s->str_len);
        } else {
                temp = xrealloc(s->str_ops, s->str_s, s->str_size, newsize);
                if (temp == NULL)
                        return (B_FALSE);
        }

        s->str_s = temp;
        s->str_size = newsize;

        return (B_TRUE);
}

/* append to s, cstrlen == 0 means entire length of string */
boolean_t
str_append(str_t *s, const char *cstr, size_t cstrlen)
{
        if (cstr != NULL && cstrlen == 0)
                cstrlen = strlen(cstr);

        const str_t src = {
                .str_s = (char *)cstr,
                .str_len = cstrlen,
                .str_ops = s->str_ops
        };

        return (str_append_str(s, &src));
}

boolean_t
str_append_str(str_t *dest, const str_t *src)
{
        /* empty string is a noop */
        if (src->str_s == NULL || src->str_len == 0)
                return (B_TRUE);

        /* if src is a reference, we can just copy that */
        if (dest->str_s == NULL && IS_REF(src)) {
                *dest = *src;
                return (B_TRUE);
        }

        if (!str_reserve(dest, src->str_len))
                return (B_FALSE);

        (void) memcpy(dest->str_s + dest->str_len, src->str_s, src->str_len);
        dest->str_len += src->str_len;
        return (B_TRUE);
}

boolean_t
str_append_c(str_t *s, char c)
{
        if (!str_reserve(s, 1))
                return (B_FALSE);

        s->str_s[s->str_len++] = c;
        return (B_TRUE);
}

boolean_t
str_insert(str_t *s, size_t idx, const char *cstr, size_t cstrlen)
{
        if (cstr == NULL)
                return (B_TRUE);

        if (cstrlen == 0)
                cstrlen = strlen(cstr);

        str_t src = {
                .str_s = (char *)cstr,
                .str_len = cstrlen,
                .str_ops = s->str_ops,
                .str_size = 0
        };

        return (str_insert_str(s, idx, &src));
}

boolean_t
str_insert_str(str_t *dest, size_t idx, const str_t *src)
{
        ASSERT3U(idx, <=, dest->str_len);

        if (idx == dest->str_len)
                return (str_append_str(dest, src));

        if (idx == 0 && dest->str_s == NULL && IS_REF(src)) {
                sysdem_ops_t *ops = dest->str_ops;
                *dest = *src;
                dest->str_ops = ops;
                return (B_TRUE);
        }

        if (!str_reserve(dest, src->str_len))
                return (B_FALSE);

        /*
         * Shift the contents of dest over at the insertion point.  Since
         * src and dest ranges will overlap, and unlike some programmers,
         * *I* can read man pages - memmove() is the appropriate function
         * to this.
         */
        (void) memmove(dest->str_s + idx + src->str_len, dest->str_s + idx,
            dest->str_len - idx);

        /*
         * However the content to insert does not overlap with the destination
         * so memcpy() is fine here.
         */
        (void) memcpy(dest->str_s + idx, src->str_s, src->str_len);
        dest->str_len += src->str_len;

        return (B_TRUE);
}

boolean_t
str_erase(str_t *s, size_t pos, size_t len)
{
        ASSERT3U(pos, <, s->str_len);
        ASSERT3U(pos + len, <=, s->str_len);

        if (IS_REF(s)) {
                if (!str_reserve(s, 0))
                        return (B_FALSE);
        }

        (void) memmove(s->str_s + pos, s->str_s + pos + len, s->str_len - len);
        s->str_len -= len;
        return (B_TRUE);
}

str_pair_t *
str_pair_init(str_pair_t *sp, sysdem_ops_t *ops)
{
        (void) memset(sp, 0, sizeof (*sp));
        str_init(&sp->strp_l, ops);
        str_init(&sp->strp_r, ops);
        return (sp);
}

void
str_pair_fini(str_pair_t *sp)
{
        str_fini(&sp->strp_l);
        str_fini(&sp->strp_r);
}

/* combine left and right parts and put result into left part */
boolean_t
str_pair_merge(str_pair_t *sp)
{
        /* if right side is empty, don't need to do anything */
        if (str_length(&sp->strp_r) == 0)
                return (B_TRUE);

        /* if left side is empty, just move right to left */
        if (str_length(&sp->strp_l) == 0) {
                str_fini(&sp->strp_l);
                sp->strp_l = sp->strp_r;
                sp->strp_r.str_s = NULL;
                sp->strp_r.str_len = sp->strp_r.str_size = 0;
                return (B_TRUE);
        }

        if (!str_append_str(&sp->strp_l, &sp->strp_r))
                return (B_FALSE);

        str_fini(&sp->strp_r);
        str_init(&sp->strp_r, sp->strp_l.str_ops);
        return (B_TRUE);
}

boolean_t
str_pair_copy(const str_pair_t *src, str_pair_t *dest)
{
        boolean_t ok = B_TRUE;

        ok &= str_copy(&src->strp_l, &dest->strp_l);
        ok &= str_copy(&src->strp_r, &dest->strp_r);

        if (!ok) {
                str_fini(&dest->strp_l);
                str_fini(&dest->strp_r);
                return (B_FALSE);
        }

        return (B_TRUE);
}

size_t
str_pair_len(const str_pair_t *sp)
{
        return (str_length(&sp->strp_l) + str_length(&sp->strp_r));
}