/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2013 by Delphix. All rights reserved.
 * Copyright (c) 2018, Joyent, Inc.
 * Copyright (c) 2013 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
 */
/*
 * This file contains all of the interfaces for mdb's tab completion engine.
 * Currently some interfaces are private to mdb and its internal implementation,
 * those are in mdb_tab.h. Other pieces are public interfaces. Those are in
 * mdb_modapi.h.
 *
 * Memory allocations in tab completion context have to be done very carefully.
 * We need to think of ourselves as the same as any other command that is being
 * executed by the user, which means we must use UM_GC to handle being
 * interrupted.
 */

#include <mdb/mdb_modapi.h>
#include <mdb/mdb_ctf.h>
#include <mdb/mdb_ctf_impl.h>
#include <mdb/mdb_string.h>
#include <mdb/mdb_module.h>
#include <mdb/mdb_debug.h>
#include <mdb/mdb_print.h>
#include <mdb/mdb_nv.h>
#include <mdb/mdb_tab.h>
#include <mdb/mdb_target.h>
#include <mdb/mdb.h>

#include <ctype.h>

/*
 * There may be another way to do this, but this works well enough.
 */
#define COMMAND_SEPARATOR "::"

/*
 * find_command_start --
 *
 *      Given a buffer find the start of the last command.
 */
static char *
tab_find_command_start(char *buf)
{
        char *offset = strstr(buf, COMMAND_SEPARATOR);

        if (offset == NULL)
                return (NULL);

        for (;;) {
                char *next = strstr(offset + strlen(COMMAND_SEPARATOR),
                    COMMAND_SEPARATOR);

                if (next == NULL) {
                        return (offset);
                }

                offset = next;
        }
}

/*
 * get_dcmd --
 *
 *      Given a buffer containing a command and its argument return
 *      the name of the command and the offset in the buffer where
 *      the command arguments start.
 *
 *      Note: This will modify the buffer.
 */
char *
tab_get_dcmd(char *buf, char **args, uint_t *flags)
{
        char *start = buf + strlen(COMMAND_SEPARATOR);
        char *separator = start;
        const char *end = buf + strlen(buf);
        uint_t space = 0;

        while (separator < end && !isspace(*separator))
                separator++;

        if (separator == end) {
                *args = NULL;
        } else {
                if (isspace(*separator))
                        space = 1;

                *separator++ = '\0';
                *args = separator;
        }

        if (space)
                *flags |= DCMD_TAB_SPACE;

        return (start);
}

/*
 * count_args --
 *
 *      Given a buffer containing dmcd arguments return the total number
 *      of arguments.
 *
 *      While parsing arguments we need to keep track of whether or not the last
 *      arguments ends with a trailing space.
 */
static int
tab_count_args(const char *input, uint_t *flags)
{
        const char *index;
        int argc = 0;
        uint_t space = *flags & DCMD_TAB_SPACE;
        index = input;

        while (*index != '\0') {
                while (*index != '\0' && isspace(*index)) {
                        index++;
                        space = 1;
                }

                if (*index != '\0' && !isspace(*index)) {
                        argc++;
                        space = 0;
                        while (*index != '\0' && !isspace (*index)) {
                                index++;
                        }
                }
        }

        if (space)
                *flags |= DCMD_TAB_SPACE;
        else
                *flags &= ~DCMD_TAB_SPACE;

        return (argc);
}

/*
 * copy_args --
 *
 *      Given a buffer containing dcmd arguments and an array of mdb_arg_t's
 *      initialize the string value of each mdb_arg_t.
 *
 *      Note: This will modify the buffer.
 */
static int
tab_copy_args(char *input, int argc, mdb_arg_t *argv)
{
        int i = 0;
        char *index;

        index = input;

        while (*index) {
                while (*index && isspace(*index)) {
                        index++;
                }

                if (*index && !isspace(*index)) {
                        char *end = index;

                        while (*end && !isspace(*end)) {
                                end++;
                        }

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

                        argv[i].a_type = MDB_TYPE_STRING;
                        argv[i].a_un.a_str = index;

                        index = end;
                        i++;
                }
        }

        if (i != argc)
                return (-1);

        return (0);
}

/*
 * parse-buf --
 *
 *      Parse the given buffer and return the specified dcmd, the number
 *      of arguments, and array of mdb_arg_t containing the argument
 *      values.
 *
 *      Note: this will modify the specified buffer. Caller is responisble
 *      for freeing argvp.
 */
static int
tab_parse_buf(char *buf, char **dcmdp, int *argcp, mdb_arg_t **argvp,
    uint_t *flags)
{
        char *data = tab_find_command_start(buf);
        char *args_data = NULL;
        char *dcmd = NULL;
        int argc = 0;
        mdb_arg_t *argv = NULL;

        if (data == NULL) {
                return (-1);
        }

        dcmd = tab_get_dcmd(data, &args_data, flags);

        if (dcmd == NULL) {
                return (-1);
        }

        if (args_data != NULL) {
                argc = tab_count_args(args_data, flags);

                if (argc != 0) {
                        argv = mdb_alloc(sizeof (mdb_arg_t) * argc,
                            UM_SLEEP | UM_GC);

                        if (tab_copy_args(args_data, argc, argv) == -1)
                                return (-1);
                }
        }

        *dcmdp = dcmd;
        *argcp = argc;
        *argvp = argv;

        return (0);
}

/*
 * tab_command --
 *
 *      This function is executed anytime a tab is entered. It checks
 *      the current buffer to determine if there is a valid dmcd,
 *      if that dcmd has a tab completion handler it will invoke it.
 *
 *      This function returns the string (if any) that should be added to the
 *      existing buffer to complete it.
 */
int
mdb_tab_command(mdb_tab_cookie_t *mcp, const char *buf)
{
        char *data;
        char *dcmd = NULL;
        int argc = 0;
        mdb_arg_t *argv = NULL;
        int ret = 0;
        mdb_idcmd_t *cp;
        uint_t flags = 0;

        /*
         * Parsing the command and arguments will modify the buffer
         * (replacing spaces with \0), so make a copy of the specified
         * buffer first.
         */
        data = mdb_alloc(strlen(buf) + 1, UM_SLEEP | UM_GC);
        (void) strcpy(data, buf);

        /*
         * Get the specified dcmd and arguments from the buffer.
         */
        ret = tab_parse_buf(data, &dcmd, &argc, &argv, &flags);

        /*
         * Match against global symbols if the input is not a dcmd
         */
        if (ret != 0) {
                (void) mdb_tab_complete_global(mcp, buf);
                goto out;
        }

        /*
         * Check to see if the buffer contains a valid dcmd
         */
        cp = mdb_dcmd_lookup(dcmd);

        /*
         * When argc is zero it indicates that we are trying to tab complete
         * a dcmd or a global symbol. Note, that if there isn't the start of
         * a dcmd, i.e. ::, then we will have already bailed in the call to
         * tab_parse_buf.
         */
        if (cp == NULL && argc != 0) {
                goto out;
        }

        /*
         * Invoke the command specific tab completion handler or the built in
         * dcmd one if there is no dcmd.
         */
        if (cp == NULL)
                (void) mdb_tab_complete_dcmd(mcp, dcmd);
        else
                mdb_call_tab(cp, mcp, flags, argc, argv);

out:
        return (mdb_tab_size(mcp));
}

static int
tab_complete_dcmd(mdb_var_t *v, void *arg)
{
        mdb_idcmd_t *idcp = mdb_nv_get_cookie(mdb_nv_get_cookie(v));
        mdb_tab_cookie_t *mcp = (mdb_tab_cookie_t *)arg;

        /*
         * The way that mdb is implemented, even commands like $C will show up
         * here. As such, we don't want to match anything that doesn't start
         * with an alpha or number. While nothing currently appears (via a
         * cursory search with mdb -k) to start with a capital letter or a
         * number, we'll support them anyways.
         */
        if (!isalnum(idcp->idc_name[0]))
                return (0);

        mdb_tab_insert(mcp, idcp->idc_name);
        return (0);
}

int
mdb_tab_complete_dcmd(mdb_tab_cookie_t *mcp, const char *dcmd)
{
        if (dcmd != NULL)
                mdb_tab_setmbase(mcp, dcmd);
        mdb_nv_sort_iter(&mdb.m_dcmds, tab_complete_dcmd, mcp,
            UM_GC | UM_SLEEP);
        return (0);
}

static int
tab_complete_walker(mdb_var_t *v, void *arg)
{
        mdb_iwalker_t *iwp = mdb_nv_get_cookie(mdb_nv_get_cookie(v));
        mdb_tab_cookie_t *mcp = arg;

        mdb_tab_insert(mcp, iwp->iwlk_name);
        return (0);
}

int
mdb_tab_complete_walker(mdb_tab_cookie_t *mcp, const char *walker)
{
        if (walker != NULL)
                mdb_tab_setmbase(mcp, walker);
        mdb_nv_sort_iter(&mdb.m_walkers, tab_complete_walker, mcp,
            UM_GC | UM_SLEEP);

        return (0);
}

mdb_tab_cookie_t *
mdb_tab_init(void)
{
        mdb_tab_cookie_t *mcp;

        mcp = mdb_zalloc(sizeof (mdb_tab_cookie_t), UM_SLEEP | UM_GC);
        (void) mdb_nv_create(&mcp->mtc_nv, UM_SLEEP | UM_GC);

        return (mcp);
}

size_t
mdb_tab_size(mdb_tab_cookie_t *mcp)
{
        return (mdb_nv_size(&mcp->mtc_nv));
}

/*
 * Determine whether the specified name is a valid tab completion for
 * the given command. If the name is a valid tab completion then
 * it will be saved in the mdb_tab_cookie_t.
 */
void
mdb_tab_insert(mdb_tab_cookie_t *mcp, const char *name)
{
        size_t matches, index;
        mdb_var_t *v;

        /*
         * If we have a match set, then we want to verify that we actually match
         * it.
         */
        if (strncmp(name, mcp->mtc_base, strlen(mcp->mtc_base)) != 0)
                return;

        v = mdb_nv_lookup(&mcp->mtc_nv, name);
        if (v != NULL)
                return;

        (void) mdb_nv_insert(&mcp->mtc_nv, name, NULL, 0, MDB_NV_RDONLY);

        matches = mdb_tab_size(mcp);
        if (matches == 1) {
                (void) strlcpy(mcp->mtc_match, name, MDB_SYM_NAMLEN);
        } else {
                index = 0;
                while (mcp->mtc_match[index] &&
                    mcp->mtc_match[index] == name[index])
                        index++;

                mcp->mtc_match[index] = '\0';
        }
}

/*ARGSUSED*/
static int
tab_print_cb(mdb_var_t *v, void *ignored)
{
        mdb_printf("%s\n", mdb_nv_get_name(v));
        return (0);
}

void
mdb_tab_print(mdb_tab_cookie_t *mcp)
{
        mdb_nv_sort_iter(&mcp->mtc_nv, tab_print_cb, NULL, UM_SLEEP | UM_GC);
}

const char *
mdb_tab_match(mdb_tab_cookie_t *mcp)
{
        return (mcp->mtc_match + strlen(mcp->mtc_base));
}

void
mdb_tab_setmbase(mdb_tab_cookie_t *mcp, const char *base)
{
        (void) strlcpy(mcp->mtc_base, base, MDB_SYM_NAMLEN);
}

/*
 * This function is currently a no-op due to the fact that we have to GC because
 * we're in command context.
 */
/*ARGSUSED*/
void
mdb_tab_fini(mdb_tab_cookie_t *mcp)
{
}

/*ARGSUSED*/
static int
tab_complete_global(void *arg, const GElf_Sym *sym, const char *name,
    const mdb_syminfo_t *sip, const char *obj)
{
        mdb_tab_cookie_t *mcp = arg;
        mdb_tab_insert(mcp, name);
        return (0);
}

/*
 * This function tab completes against all loaded global symbols.
 */
int
mdb_tab_complete_global(mdb_tab_cookie_t *mcp, const char *name)
{
        mdb_tab_setmbase(mcp, name);
        (void) mdb_tgt_symbol_iter(mdb.m_target, MDB_TGT_OBJ_EVERY,
            MDB_TGT_SYMTAB, MDB_TGT_BIND_ANY | MDB_TGT_TYPE_OBJECT |
            MDB_TGT_TYPE_FUNC, tab_complete_global, mcp);
        return (0);
}

/*
 * This function takes a ctf id and determines whether or not the associated
 * type should be considered as a potential match for the given tab
 * completion command. We verify that the type itself is valid
 * for completion given the current context of the command, resolve
 * its actual name, and then pass it off to mdb_tab_insert to determine
 * if it's an actual match.
 */
static int
tab_complete_type(mdb_ctf_id_t id, void *arg)
{
        int rkind;
        char buf[MDB_SYM_NAMLEN];
        mdb_ctf_id_t rid;
        mdb_tab_cookie_t *mcp = arg;
        uint_t flags = (uint_t)(uintptr_t)mcp->mtc_cba;

        /*
         * CTF data includes types that mdb commands don't understand. Before
         * we resolve the actual type prune any entry that is a type we
         * don't care about.
         */
        switch (mdb_ctf_type_kind(id)) {
        case CTF_K_CONST:
        case CTF_K_RESTRICT:
        case CTF_K_VOLATILE:
                return (0);
        }

        if (mdb_ctf_type_resolve(id, &rid) != 0)
                return (1);

        rkind = mdb_ctf_type_kind(rid);

        if ((flags & MDB_TABC_MEMBERS) && rkind != CTF_K_STRUCT &&
            rkind != CTF_K_UNION)
                return (0);

        if ((flags & MDB_TABC_NOPOINT) && rkind == CTF_K_POINTER)
                return (0);

        if ((flags & MDB_TABC_NOARRAY) && rkind == CTF_K_ARRAY)
                return (0);

        (void) mdb_ctf_type_name(id, buf, sizeof (buf));

        mdb_tab_insert(mcp, buf);
        return (0);
}

/*ARGSUSED*/
static int
mdb_tab_complete_module(void *data, const mdb_map_t *mp, const char *name)
{
        (void) mdb_ctf_type_iter(name, tab_complete_type, data);
        return (0);
}

int
mdb_tab_complete_type(mdb_tab_cookie_t *mcp, const char *name, uint_t flags)
{
        mdb_tgt_t *t = mdb.m_target;

        mcp->mtc_cba = (void *)(uintptr_t)flags;
        if (name != NULL)
                mdb_tab_setmbase(mcp, name);

        (void) mdb_tgt_object_iter(t, mdb_tab_complete_module, mcp);
        (void) mdb_ctf_type_iter(MDB_CTF_SYNTHETIC_ITER, tab_complete_type,
            mcp);
        return (0);
}

/*ARGSUSED*/
static int
tab_complete_member(const char *name, mdb_ctf_id_t id, ulong_t off, void *arg)
{
        mdb_tab_cookie_t *mcp = arg;
        mdb_tab_insert(mcp, name);
        return (0);
}

int
mdb_tab_complete_member_by_id(mdb_tab_cookie_t *mcp, mdb_ctf_id_t id,
    const char *member)
{
        if (member != NULL)
                mdb_tab_setmbase(mcp, member);
        (void) mdb_ctf_member_iter(id, tab_complete_member, mcp,
            MDB_CTF_F_ITER_ANON);
        return (0);
}

int
mdb_tab_complete_member(mdb_tab_cookie_t *mcp, const char *type,
    const char *member)
{
        mdb_ctf_id_t id;

        if (mdb_ctf_lookup_by_name(type, &id) != 0)
                return (-1);

        return (mdb_tab_complete_member_by_id(mcp, id, member));
}

int
mdb_tab_complete_mt(mdb_tab_cookie_t *mcp, uint_t flags, int argc,
    const mdb_arg_t *argv)
{
        char tn[MDB_SYM_NAMLEN];
        int ret;

        if (argc == 0 && !(flags & DCMD_TAB_SPACE))
                return (0);

        if (argc == 0)
                return (mdb_tab_complete_type(mcp, NULL, MDB_TABC_MEMBERS));

        if ((ret = mdb_tab_typename(&argc, &argv, tn, sizeof (tn))) < 0)
                return (ret);

        if (argc == 1 && (!(flags & DCMD_TAB_SPACE) || ret == 1))
                return (mdb_tab_complete_type(mcp, tn, MDB_TABC_MEMBERS));

        if (argc == 1 && (flags & DCMD_TAB_SPACE))
                return (mdb_tab_complete_member(mcp, tn, NULL));

        if (argc == 2)
                return (mdb_tab_complete_member(mcp, tn, argv[1].a_un.a_str));

        return (0);
}

/*
 * This is similar to mdb_print.c's args_to_typename, but it has subtle
 * differences surrounding how the strings of one element are handled that have
 * 'struct', 'enum', or 'union' in them and instead works with them for tab
 * completion purposes.
 */
int
mdb_tab_typename(int *argcp, const mdb_arg_t **argvp, char *buf, size_t len)
{
        int argc = *argcp;
        const mdb_arg_t *argv = *argvp;

        if (argc < 1 || argv->a_type != MDB_TYPE_STRING)
                return (DCMD_USAGE);

        if (strcmp(argv->a_un.a_str, "struct") == 0 ||
            strcmp(argv->a_un.a_str, "enum") == 0 ||
            strcmp(argv->a_un.a_str, "union") == 0) {
                if (argc == 1) {
                        (void) mdb_snprintf(buf, len, "%s ",
                            argv[0].a_un.a_str);
                        return (1);
                }

                if (argv[1].a_type != MDB_TYPE_STRING)
                        return (DCMD_USAGE);

                (void) mdb_snprintf(buf, len, "%s %s",
                    argv[0].a_un.a_str, argv[1].a_un.a_str);

                *argcp = argc - 1;
                *argvp = argv + 1;
        } else {
                (void) mdb_snprintf(buf, len, "%s", argv[0].a_un.a_str);
        }

        return (0);
}