/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024 Arm Ltd.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/types.h>
#include <sys/errno.h>

#include <machine/atomic.h>
#include <machine/cpu.h>
#include <machine/cpufunc.h>

#include <assert.h>
#include <err.h>
#include <getopt.h>
#include <pthread.h>
#include <stdarg.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/* #define DEBUG_BUFRING */

#ifdef DEBUG_BUFRING
static void
panic(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        va_end(ap);
        fprintf(stderr, "\n");
        exit(1);
}
#endif

static void
critical_enter(void)
{
}

static void
critical_exit(void)
{
}

#include "../../../sys/sys/buf_ring.h"

#define PROD_ITERATIONS 100000000

static enum {
        CT_UNKNOWN,
        CT_MC,
        CT_MC_MT,
        CT_SC,
        CT_PEEK,
        CT_PEEK_CLEAR,
} cons_type = CT_UNKNOWN;

static unsigned int prod_count;

static struct buf_ring *br;
static _Atomic bool prod_done = false;
static _Atomic int prod_done_count = 0;
static _Atomic size_t total_cons_count = 0;

static uint64_t *mt_seen;

static void *
producer(void *arg)
{
        int id, rv;

        id = (int)(uintptr_t)arg;

        for (size_t i = 0; i < PROD_ITERATIONS;) {
                rv = buf_ring_enqueue(br, (void *)(i * prod_count + 1 + id));
                if (rv == 0) {
                        i++;
                }
        }
        if ((unsigned int)atomic_fetch_add(&prod_done_count, 1) ==
            (prod_count - 1))
                atomic_store(&prod_done, true);

        return (NULL);
}

static void *
consumer(void *arg)
{
        void *val;
        size_t *max_vals;
        size_t consume_count, curr;
        int id;

        (void)arg;

        max_vals = calloc(prod_count, sizeof(*max_vals));
        assert(max_vals != NULL);

        /* Set the initial value to be the expected value */
        for (unsigned int i = 1; i < prod_count; i++) {
                max_vals[i] = (int)(i - prod_count);
        }

        consume_count = 0;
        while (!atomic_load(&prod_done) || !buf_ring_empty(br)) {
                switch(cons_type) {
                case CT_MC:
                case CT_MC_MT:
                        val = buf_ring_dequeue_mc(br);
                        break;
                case CT_SC:
                        val = buf_ring_dequeue_sc(br);
                        break;
                case CT_PEEK:
                        val = buf_ring_peek(br);
                        if (val != NULL)
                                buf_ring_advance_sc(br);
                        break;
                case CT_PEEK_CLEAR:
                        val = buf_ring_peek_clear_sc(br);
                        if (val != NULL)
                                buf_ring_advance_sc(br);
                        break;
                case CT_UNKNOWN:
                        __unreachable();
                }
                if (val != NULL) {
                        consume_count++;
                        curr = (size_t)(uintptr_t)val;
                        id = curr % prod_count;
                        if (cons_type != CT_MC_MT) {
                                if (curr != max_vals[id] + prod_count)
                                        printf("Incorrect val: %zu Expect: %zu "
                                            "Difference: %zd\n", curr,
                                            max_vals[id] + prod_count,
                                            curr - max_vals[id] - prod_count);
                        } else {
                                size_t idx, bit;

                                idx = ((size_t)(uintptr_t)val - 1) /
                                    (sizeof(*mt_seen) * NBBY);
                                bit = ((size_t)(uintptr_t)val - 1) %
                                    (sizeof(*mt_seen) * NBBY);

                                if (atomic_testandset_64(&mt_seen[idx], bit))
                                        printf("Repeat ID: %zx\n", (size_t)(uintptr_t)val);
                        }

                        max_vals[id] = (uintptr_t)val;
                }
        }

        atomic_fetch_add(&total_cons_count, consume_count);

        for (unsigned int i = 0; i < prod_count; i++)
                printf("max[%d] = %zu\n", i, max_vals[i]);

        return (NULL);
}

static struct option longopts[] = {
        { "buf-size",   required_argument,      NULL,   'b'     },
        { "cons-type",  required_argument,      NULL,   'c'     },
        { "prod-count", required_argument,      NULL,   'p'     },
        { "help",       no_argument,            NULL,   'h'     },
        { NULL,         0,                      NULL,    0      },
};

static void
usage(void)
{
        errx(1, "test --cons-type=<mc|mc-mt|sc|peek|peek-clear> --prod-count=<prod thread count> [--buf-size=<buf_ring size>]");
}

static uint32_t
next_power_of_2(uint32_t x)
{
        x--;
        x |= x >> 1;
        x |= x >> 2;
        x |= x >> 4;
        x |= x >> 8;
        x |= x >> 16;
        x++;
        return (x);
}

int
main(int argc, char *argv[])
{
        pthread_t *prod;
        pthread_t cons[2];
        const char *errstr;
        uint32_t size;
        int ch, ret;

        size = 0;
        while ((ch = getopt_long(argc, argv, "bf:", longopts, NULL)) != -1) {
                switch(ch) {
                case 'b':
                        errstr = NULL;
                        size = strtonum(optarg, 1, UINT_MAX, &errstr);
                        if (errstr != NULL) {
                                errx(1, "--bufsize=%s: %s", optarg, errstr);
                        }
                        if (!powerof2(size)) {
                                errx(1, "--bufsize needs a power of 2 size");
                        }
                        break;
                case 'c':
                        if (strcmp(optarg, "mc") == 0) {
                                cons_type = CT_MC;
                        } else if (strcmp(optarg, "mc-mt") == 0) {
                                cons_type = CT_MC_MT;
                        } else if (strcmp(optarg, "sc") == 0) {
                                cons_type = CT_SC;
                        } else if (strcmp(optarg, "peek") == 0) {
                                cons_type = CT_PEEK;
                        } else if (strcmp(optarg, "peek-clear") == 0) {
                                cons_type = CT_PEEK_CLEAR;
                        } else {
                                errx(1, "Unknown --cons-type: %s", optarg);
                        }
                        break;
                case 'p':
                        errstr = NULL;
                        prod_count = strtonum(optarg, 1, UINT_MAX, &errstr);
                        if (errstr != NULL) {
                                errx(1, "--prod-count=%s: %s", optarg, errstr);
                        }
                        break;
                case 'h':
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (cons_type == CT_UNKNOWN)
                errx(1, "No cons-type set");

        if (prod_count == 0)
                errx(1, "prod-count is not set");

        if (size == 0)
                size = next_power_of_2(prod_count);

        if (cons_type == CT_MC_MT) {
                size_t entries;

                entries = (size_t)PROD_ITERATIONS * prod_count;
                entries = roundup2(entries, sizeof(*mt_seen));
                mt_seen = calloc(entries / (sizeof(*mt_seen) * NBBY),
                    sizeof(*mt_seen));
        }

        br = buf_ring_alloc(size);

        ret = pthread_create(&cons[0], NULL, consumer, NULL);
        assert(ret == 0);
        if (cons_type == CT_MC_MT) {
                ret = pthread_create(&cons[1], NULL, consumer, NULL);
                assert(ret == 0);
        }

        prod = calloc(prod_count, sizeof(*prod));
        assert(prod != NULL);
        for (unsigned i = 0; i < prod_count; i++) {
                ret = pthread_create(&prod[i], NULL, producer,
                    (void *)(uintptr_t)i);
                assert(ret == 0);
        }

        for (unsigned int i = 0; i < prod_count; i++) {
                ret = pthread_join(prod[i], NULL);
                assert(ret == 0);
        }
        ret = pthread_join(cons[0], NULL);
        assert(ret == 0);
        if (cons_type == CT_MC_MT) {
                ret = pthread_join(cons[1], NULL);
                assert(ret == 0);
        }

        printf("Expected: %zu\n", (size_t)PROD_ITERATIONS * prod_count);
        printf("Received: %zu\n", total_cons_count);

        buf_ring_free(br);

        return (0);
}