/*
 * Copyright (C) 2016 Oracle.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
 */

/*
 * The point here is to store the relationships between two variables.
 * Ie:  y > x.
 * To do that we create a state with the two variables in alphabetical order:
 * ->name = "x vs y" and the state would be "<".  On the false path the state
 * would be ">=".
 *
 * Part of the trick of it is that if x or y is modified then we need to reset
 * the state.  We need to keep a list of all the states which depend on x and
 * all the states which depend on y.  The link_id code handles this.
 *
 */

#include "smatch.h"
#include "smatch_extra.h"
#include "smatch_slist.h"

static int compare_id;
static int link_id;

static struct smatch_state *alloc_link_state(struct string_list *links)
{
        struct smatch_state *state;
        static char buf[256];
        char *tmp;
        int i;

        state = __alloc_smatch_state(0);

        i = 0;
        FOR_EACH_PTR(links, tmp) {
                if (!i++) {
                        snprintf(buf, sizeof(buf), "%s", tmp);
                } else {
                        append(buf, ", ", sizeof(buf));
                        append(buf, tmp, sizeof(buf));
                }
        } END_FOR_EACH_PTR(tmp);

        state->name = alloc_sname(buf);
        state->data = links;
        return state;
}

static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
{
        struct smatch_state *ret;
        struct string_list *links;

        links = combine_string_lists(s1->data, s2->data);
        ret = alloc_link_state(links);
        return ret;
}

static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
{
        struct smatch_state *old_state, *new_state;
        struct string_list *links;
        char *new;

        old_state = get_state(link_id, var, sym);
        if (old_state)
                links = clone_str_list(old_state->data);
        else
                links = NULL;

        new = alloc_sname(link);
        insert_string(&links, new);

        new_state = alloc_link_state(links);
        set_state(link_id, var, sym, new_state);
}

static void add_comparison_var_sym(const char *left_name,
                struct var_sym_list *left_vsl,
                int comparison,
                const char *right_name, struct var_sym_list *right_vsl)
{
        struct smatch_state *state;
        struct var_sym *vs;
        char state_name[256];

        if (strcmp(left_name, right_name) > 0) {
                const char *tmp_name = left_name;
                struct var_sym_list *tmp_vsl = left_vsl;

                left_name = right_name;
                left_vsl = right_vsl;
                right_name = tmp_name;
                right_vsl = tmp_vsl;
                comparison = flip_comparison(comparison);
        }
        snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
        state = alloc_compare_state(NULL, left_name, left_vsl, comparison, NULL, right_name, right_vsl);

        set_state(compare_id, state_name, NULL, state);

        FOR_EACH_PTR(left_vsl, vs) {
                save_link_var_sym(vs->var, vs->sym, state_name);
        } END_FOR_EACH_PTR(vs);
        FOR_EACH_PTR(right_vsl, vs) {
                save_link_var_sym(vs->var, vs->sym, state_name);
        } END_FOR_EACH_PTR(vs);
}

/*
 * This is quite a bit more limitted, less ambitious, simpler compared to
 * smatch_camparison.c.
 */
void __compare_param_limit_hook(struct expression *left_expr, struct expression *right_expr,
                                const char *state_name,
                                struct smatch_state *true_state, struct smatch_state *false_state)
{
        char *left_name = NULL;
        char *right_name = NULL;
        char *tmp_name = NULL;
        struct symbol *left_sym, *right_sym, *tmp_sym;

        left_name = expr_to_var_sym(left_expr, &left_sym);
        if (!left_name || !left_sym)
                goto free;
        right_name = expr_to_var_sym(right_expr, &right_sym);
        if (!right_name || !right_sym)
                goto free;

        if (get_param_num_from_sym(left_sym) < 0 ||
            get_param_num_from_sym(right_sym) < 0)
                return;

        tmp_name = get_other_name_sym(left_name, left_sym, &tmp_sym);
        if (tmp_name) {
                free_string(left_name);
                left_name = tmp_name;
                left_sym = tmp_sym;
        }

        tmp_name = get_other_name_sym(right_name, right_sym, &tmp_sym);
        if (tmp_name) {
                free_string(right_name);
                right_name = tmp_name;
                right_sym = tmp_sym;
        }

        if (param_was_set_var_sym(left_name, left_sym))
                return;
        if (param_was_set_var_sym(right_name, right_sym))
                return;

        set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
        save_link_var_sym(left_name, left_sym, state_name);
        save_link_var_sym(right_name, right_sym, state_name);
free:
        free_string(left_name);
        free_string(right_name);
}

static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
{
        struct sm_state *tmp;
        struct string_list *links;
        char *link;
        struct sm_state *sm;
        struct compare_data *data;
        struct var_sym *left, *right;
        int left_param, right_param;
        static char left_buf[248];
        static char right_buf[248];
        static char info_buf[256];
        const char *tmp_name;

        FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
                links = tmp->state->data;
                FOR_EACH_PTR(links, link) {
                        sm = get_sm_state(compare_id, link, NULL);
                        if (!sm)
                                continue;
                        data = sm->state->data;
                        if (!data || !data->comparison)
                                continue;
                        if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
                            ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
                                continue;
                        left = first_ptr_list((struct ptr_list *)data->left_vsl);
                        right = first_ptr_list((struct ptr_list *)data->right_vsl);
                        if (left->sym == right->sym &&
                            strcmp(left->var, right->var) == 0)
                                continue;
                        /*
                         * Both parameters link to this comparison so only
                         * record the first one.
                         */
                        if (left->sym != tmp->sym ||
                            strcmp(left->var, tmp->name) != 0)
                                continue;

                        left_param = get_param_num_from_sym(left->sym);
                        right_param = get_param_num_from_sym(right->sym);
                        if (left_param < 0 || right_param < 0) /* can't happen hopefully */
                                continue;

                        tmp_name = get_param_name_var_sym(left->var, left->sym);
                        if (!tmp_name)
                                continue;
                        snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);

                        tmp_name = get_param_name_var_sym(right->var, right->sym);
                        if (!tmp_name || tmp_name[0] != '$')
                                continue;
                        snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);

                        snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_buf);
                        sql_insert_return_states(return_id, return_ranges,
                                        COMPARE_LIMIT, left_param, left_buf, info_buf);
                } END_FOR_EACH_PTR(link);

        } END_FOR_EACH_SM(tmp);
}

static int parse_comparison(char **value, int *op)
{

        *op = **value;

        switch (*op) {
        case '<':
                (*value)++;
                if (**value == '=') {
                        (*value)++;
                        *op = SPECIAL_LTE;
                }
                break;
        case '=':
                (*value)++;
                (*value)++;
                *op = SPECIAL_EQUAL;
                break;
        case '!':
                (*value)++;
                (*value)++;
                *op = SPECIAL_NOTEQUAL;
                break;
        case '>':
                (*value)++;
                if (**value == '=') {
                        (*value)++;
                        *op = SPECIAL_GTE;
                }
                break;
        default:
                return 0;
        }

        if (**value != ' ') {
                sm_perror("parsing comparison.  %s", *value);
                return 0;
        }

        (*value)++;
        return 1;
}

static int split_op_param_key(char *value, int *op, int *param, char **key)
{
        static char buf[256];
        char *p;

        if (!parse_comparison(&value, op))
                return 0;

        snprintf(buf, sizeof(buf), "%s", value);

        p = buf;
        if (*p++ != '$')
                return 0;

        *param = atoi(p);
        if (*param < 0 || *param > 99)
                return 0;
        p++;
        if (*param > 9)
                p++;
        p--;
        *p = '$';
        *key = p;

        return 1;
}

static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
{
        struct expression *left_arg, *right_arg;
        char *left_name = NULL;
        struct symbol *left_sym;
        char *right_name = NULL;
        struct symbol *right_sym;
        int op;
        int right_param;
        char *right_key;
        struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;

        while (expr->type == EXPR_ASSIGNMENT)
                expr = strip_expr(expr->right);
        if (expr->type != EXPR_CALL)
                return;

        if (!split_op_param_key(value, &op, &right_param, &right_key))
                return;

        left_arg = get_argument_from_call_expr(expr->args, left_param);
        if (!left_arg)
                return;

        right_arg = get_argument_from_call_expr(expr->args, right_param);
        if (!right_arg)
                return;

        left_name = get_variable_from_key(left_arg, key, &left_sym);
        if (!left_name || !left_sym)
                goto free;
        if (get_param_num_from_sym(left_sym) < 0)
                goto free;

        right_name = get_variable_from_key(right_arg, right_key, &right_sym);
        if (!right_name || !right_sym)
                goto free;
        if (get_param_num_from_sym(right_sym) < 0)
                goto free;

        add_var_sym(&left_vsl, left_name, left_sym);
        add_var_sym(&right_vsl, right_name, right_sym);

        add_comparison_var_sym(left_name, left_vsl, op, right_name, right_vsl);

free:
        free_string(left_name);
        free_string(right_name);
}

void register_param_compare_limit(int id)
{
        compare_id = id;

        set_dynamic_states(compare_id);
        add_merge_hook(compare_id, &merge_compare_states);
        add_split_return_callback(&print_return_comparison);

        select_return_states_hook(COMPARE_LIMIT, &db_return_comparison);
}

void register_param_compare_limit_links(int id)
{
        link_id = id;

        set_dynamic_states(link_id);
        add_merge_hook(link_id, &merge_links);
}