/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*  Fluent Bit
 *  ==========
 *  Copyright (C) 2015-2026 The Fluent Bit Authors
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include <fluent-bit/flb_info.h>
#include <fluent-bit/flb_mem.h>
#include <fluent-bit/flb_str.h>
#include <fluent-bit/flb_input.h>
#include <fluent-bit/flb_input_chunk.h>
#include <fluent-bit/flb_output.h>
#include <fluent-bit/flb_config.h>
#include <fluent-bit/flb_router.h>
#include <fluent-bit/flb_routes_mask.h>

#ifdef FLB_HAVE_REGEX
#include <onigmo.h>
#endif

#include <string.h>

/* wildcard support */
/* match should be null terminated; tag length is provided explicitly. */
static inline int router_match(const char *tag, int tag_len,
                               const char *match,
                               void *match_r)
{
    int ret = FLB_FALSE;
    const char *tag_end;
    const char *tag_cursor;
    size_t remaining;
    static const char empty_tag[] = "";

    if (tag_len < 0) {
        return FLB_FALSE;
    }

    if (!tag) {
        if (tag_len == 0) {
            tag = empty_tag;
        }
        else {
            return FLB_FALSE;
        }
    }

    tag_end = tag + tag_len;
    tag_cursor = tag;
    remaining = (size_t) tag_len;

#ifdef FLB_HAVE_REGEX
    struct flb_regex *match_regex = match_r;
    int n;
    if (match_regex) {
        n = onig_match(match_regex->regex,
                       (const unsigned char *) tag,
                       (const unsigned char *) tag + tag_len,
                       (const unsigned char *) tag, 0,
                       ONIG_OPTION_NONE);
        if (n > 0) {
            return 1;
        }
    }
#else
    (void) match_r;
#endif

    if (!match) {
        return ret;
    }

    while (*match) {
        if (*match == '*') {
            while (*++match == '*'){
                /* skip successive '*' */
            }
            if (*match == '\0') {
                /*  '*' is last of string */
                ret = 1;
                break;
            }

            const char *search = tag_cursor;

            while (search < tag_end) {
                size_t span = (size_t) (tag_end - search);
                const char *pos;

                pos = memchr(search, (unsigned char) *match, span);
                if (!pos) {
                    break;
                }

#ifndef FLB_HAVE_REGEX
                if (router_match(pos, (int) (tag_end - pos), match, NULL)) {
#else
                /* We don't need to pass the regex recursively,
                 * we matched in order above
                 */
                if (router_match(pos, (int) (tag_end - pos), match, NULL)) {
#endif
                    ret = 1;
                    goto done;
                }
                search = pos + 1;
            }
            break;
        }
        else if (remaining == 0 || *tag_cursor != *match) {
            /* mismatch! */
            break;
        }
        tag_cursor++;
        remaining--;
        match++;
    }

    if (*match == '\0' && remaining == 0) {
        ret = 1;
    }

done:
    return ret;
}

int flb_router_match(const char *tag, int tag_len, const char *match,
                     void *match_regex)
{
    return router_match(tag, tag_len, match, match_regex);
}

/* Associate and input and output instances due to a previous match */
int flb_router_connect(struct flb_input_instance *in,
                       struct flb_output_instance *out)
{
    struct flb_router_path *p;

    p = flb_malloc(sizeof(struct flb_router_path));
    if (!p) {
        flb_errno();
        return -1;
    }

    p->ins = out;
    p->route = NULL;
    cfl_list_add(&p->_head, &in->routes);

    return 0;
}

int flb_router_connect_direct(struct flb_input_instance *in,
                              struct flb_output_instance *out)
{
    struct flb_router_path *p;

    p = flb_malloc(sizeof(struct flb_router_path));
    if (!p) {
        flb_errno();
        return -1;
    }

    p->ins = out;
    p->route = NULL;
    cfl_list_add(&p->_head, &in->routes_direct);

    return 0;
}

/*
 * This routine defines static routes for the plugins that have registered
 * tags. It check where data should go before the service start running, each
 * input 'instance' plugin will contain a list of destinations.
 */
int flb_router_io_set(struct flb_config *config)
{
    int in_count = 0;
    int out_count = 0;
    struct mk_list *i_head;
    struct mk_list *o_head;
    struct flb_input_instance *i_ins;
    struct flb_output_instance *o_ins;

    /* Quick setup for 1:1 */
    in_count = mk_list_size(&config->inputs);
    out_count = mk_list_size(&config->outputs);

    /* Mostly used for command line tests */
    if (in_count == 1 && out_count == 1) {
        i_ins = mk_list_entry_first(&config->inputs, struct flb_input_instance, _head);
        o_ins = mk_list_entry_first(&config->outputs, struct flb_output_instance, _head);

        if (!o_ins->match
#ifdef FLB_HAVE_REGEX
            && !o_ins->match_regex
#endif
            ) {

            o_ins->match = flb_sds_create_len("*", 1);
        }
        flb_router_connect(i_ins, o_ins);
        return 0;
    }

    /* N:M case, iterate all input instances */
    mk_list_foreach(i_head, &config->inputs) {
        i_ins = mk_list_entry(i_head, struct flb_input_instance, _head);
        if (!i_ins->p) {
            continue;
        }

        if (!i_ins->tag) {
            flb_warn("[router] NO tag for %s input instance",
                     i_ins->name);
            continue;
        }


        flb_trace("[router] input=%s tag=%s", i_ins->name, i_ins->tag);

        /* Try to find a match with output instances */
        mk_list_foreach(o_head, &config->outputs) {
            o_ins = mk_list_entry(o_head, struct flb_output_instance, _head);
            if (!o_ins->match
#ifdef FLB_HAVE_REGEX
                && !o_ins->match_regex
#endif
                ) {
                flb_warn("[router] NO match for %s output instance",
                          o_ins->name);
                continue;
            }

            if (flb_router_match(i_ins->tag, i_ins->tag_len, o_ins->match
#ifdef FLB_HAVE_REGEX
                , o_ins->match_regex
#else
                , NULL
#endif
            )) {

                flb_debug("[router] match rule %s:%s",
                          i_ins->name, o_ins->name);
                flb_router_connect(i_ins, o_ins);
            }
        }
    }

    /* Apply new router configuration if available */
    if (!cfl_list_is_empty(&config->input_routes)) {
        flb_debug("[router] new router configuration found, applying...");
        if (flb_router_apply_config(config) == -1) {
            flb_error("[router] failed to apply new router configuration");
            return -1;
        }
    }

    return 0;
}

void flb_router_exit(struct flb_config *config)
{
    struct mk_list *tmp;
    struct cfl_list *r_tmp;
    struct mk_list *head;
    struct cfl_list *r_head;
    struct flb_input_instance *in;
    struct flb_router_path *r;

    /* Iterate input plugins */
    mk_list_foreach_safe(head, tmp, &config->inputs) {
        in = mk_list_entry(head, struct flb_input_instance, _head);

        /* Iterate instance routes */
        cfl_list_foreach_safe(r_head, r_tmp, &in->routes) {
            r = cfl_list_entry(r_head, struct flb_router_path, _head);
            cfl_list_del(&r->_head);
            flb_free(r);
        }

        /* Iterate instance routes direct */
        cfl_list_foreach_safe(r_head, r_tmp, &in->routes_direct) {
            r = cfl_list_entry(r_head, struct flb_router_path, _head);
            cfl_list_del(&r->_head);
            flb_free(r);
        }
    }
}

static int router_metrics_create(struct flb_router *router)
{
    if (!router || !router->cmt) {
        return -1;
    }

    router->logs_records_total = cmt_counter_create(router->cmt,
                                                    "fluentbit",
                                                    "routing_logs",
                                                    "records_total",
                                                    "Total log records routed from input to output",
                                                    2,
                                                    (char *[]) {"input", "output"});
    if (!router->logs_records_total) {
        return -1;
    }

    router->logs_bytes_total = cmt_counter_create(router->cmt,
                                                  "fluentbit",
                                                  "routing_logs",
                                                  "bytes_total",
                                                  "Total bytes routed from input to output (logs)",
                                                  2,
                                                  (char *[]) {"input", "output"});
    if (!router->logs_bytes_total) {
        return -1;
    }

    router->logs_drop_records_total = cmt_counter_create(router->cmt,
                                                         "fluentbit",
                                                         "routing_logs",
                                                         "drop_records_total",
                                                         "Total log records dropped during routing",
                                                         2,
                                                         (char *[]) {"input", "output"});
    if (!router->logs_drop_records_total) {
        return -1;
    }

    router->logs_drop_bytes_total = cmt_counter_create(router->cmt,
                                                       "fluentbit",
                                                       "routing_logs",
                                                       "drop_bytes_total",
                                                       "Total bytes dropped during routing (logs)",
                                                       2,
                                                       (char *[]) {"input", "output"});
    if (!router->logs_drop_bytes_total) {
        return -1;
    }

    return 0;
}

struct flb_router *flb_router_create(struct flb_config *config)
{
    int ret;
    struct flb_router *router;
    (void) config;

    router = flb_calloc(1, sizeof(struct flb_router));
    if (!router) {
        flb_errno();
        return NULL;
    }

    router->cmt = cmt_create();
    if (!router->cmt) {
        flb_free(router);
        return NULL;
    }

    ret = router_metrics_create(router);
    if (ret != 0) {
        flb_error("[router] failed to create metrics");
        flb_router_destroy(router);
        return NULL;
    }

    return router;
}

void flb_router_destroy(struct flb_router *router)
{
    if (!router) {
        return;
    }

    flb_routes_empty_mask_destroy(router);

    if (router->cmt) {
        cmt_destroy(router->cmt);
    }

    flb_free(router);
}
