// SPDX-License-Identifier: GPL-2.0
#include "cache.h"
#include "config.h"
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <subcmd/help.h>
#include "../builtin.h"
#include "levenshtein.h"
#include <linux/zalloc.h>

static int autocorrect;

static int perf_unknown_cmd_config(const char *var, const char *value,
                                   void *cb __maybe_unused)
{
        if (!strcmp(var, "help.autocorrect"))
                return perf_config_int(&autocorrect, var,value);

        return 0;
}

static int levenshtein_compare(const void *p1, const void *p2)
{
        const struct cmdname *const *c1 = p1, *const *c2 = p2;
        const char *s1 = (*c1)->name, *s2 = (*c2)->name;
        int l1 = (*c1)->len;
        int l2 = (*c2)->len;
        return l1 != l2 ? l1 - l2 : strcmp(s1, s2);
}

static int add_cmd_list(struct cmdnames *cmds, struct cmdnames *old)
{
        unsigned int i, nr = cmds->cnt + old->cnt;
        void *tmp;

        if (nr > cmds->alloc) {
                /* Choose bigger one to alloc */
                if (alloc_nr(cmds->alloc) < nr)
                        cmds->alloc = nr;
                else
                        cmds->alloc = alloc_nr(cmds->alloc);
                tmp = realloc(cmds->names, cmds->alloc * sizeof(*cmds->names));
                if (!tmp)
                        return -1;
                cmds->names = tmp;
        }
        for (i = 0; i < old->cnt; i++)
                cmds->names[cmds->cnt++] = old->names[i];
        zfree(&old->names);
        old->cnt = 0;
        return 0;
}

const char *help_unknown_cmd(const char *cmd, struct cmdnames *main_cmds)
{
        unsigned int i, n = 0, best_similarity = 0;
        struct cmdnames other_cmds;

        memset(&other_cmds, 0, sizeof(other_cmds));

        perf_config(perf_unknown_cmd_config, NULL);

        load_command_list("perf-", main_cmds, &other_cmds);

        if (add_cmd_list(main_cmds, &other_cmds) < 0) {
                fprintf(stderr, "ERROR: Failed to allocate command list for unknown command.\n");
                goto end;
        }
        qsort(main_cmds->names, main_cmds->cnt,
              sizeof(main_cmds->names), cmdname_compare);
        uniq(main_cmds);

        if (main_cmds->cnt) {
                /* This reuses cmdname->len for similarity index */
                for (i = 0; i < main_cmds->cnt; ++i) {
                        main_cmds->names[i]->len =
                                levenshtein(cmd, main_cmds->names[i]->name,
                                        /*swap_penalty=*/0,
                                        /*substition_penality=*/2,
                                        /*insertion_penality=*/1,
                                        /*deletion_penalty=*/1);
                }
                qsort(main_cmds->names, main_cmds->cnt,
                      sizeof(*main_cmds->names), levenshtein_compare);

                best_similarity = main_cmds->names[0]->len;
                n = 1;
                while (n < main_cmds->cnt && best_similarity == main_cmds->names[n]->len)
                        ++n;
        }

        if (autocorrect && n == 1) {
                const char *assumed = main_cmds->names[0]->name;

                main_cmds->names[0] = NULL;
                clean_cmdnames(&other_cmds);
                fprintf(stderr, "WARNING: You called a perf program named '%s', "
                        "which does not exist.\n"
                        "Continuing under the assumption that you meant '%s'\n",
                        cmd, assumed);
                if (autocorrect > 0) {
                        fprintf(stderr, "in %0.1f seconds automatically...\n",
                                (float)autocorrect/10.0);
                        poll(NULL, 0, autocorrect * 100);
                }
                return assumed;
        }

        fprintf(stderr, "perf: '%s' is not a perf-command. See 'perf --help'.\n", cmd);

        if (main_cmds->cnt && best_similarity < 6) {
                fprintf(stderr, "\nDid you mean %s?\n",
                        n < 2 ? "this": "one of these");

                for (i = 0; i < n; i++)
                        fprintf(stderr, "\t%s\n", main_cmds->names[i]->name);
        }
end:
        clean_cmdnames(&other_cmds);
        return NULL;
}