reaction.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h> /* SCNu64 */
#include <assert.h>

#include "discord.h"
#include "log.h"

void
print_usage(void)
{
    printf(
        "\n\nThis bot demonstrates how easy it is to create/delete"
        " reactions from a message.\n"
        "1. Reply to a message with 'reaction.get_users <emoji>' to get all "
        "the users who reacted with that particular emoji\n"
        "2. Reply to a message with 'reaction.create <emoji>' and the bot "
        "will react with that emoji\n"
        "3. Reply to a message with 'reaction.delete <emoji>' to delete all "
        "reactions with a particular emoji\n"
        "4. Reply to a message with 'reaction.delete_all' to delete all "
        "reactions\n"
        "5. Reply to a message with 'reaction.delete_self <emoji>' to delete "
        "your reaction with a particular emoji\n"
        "6. Reply to a message with 'reaction.delete_user <user_id> <emoji>' "
        "to delete the user reaction with a particular emoji\n"
        "\nTYPE ANY KEY TO START BOT\n");
}

void
on_ready(struct discord *client, const struct discord_ready *event)
{
    log_info("Reaction-Bot succesfully connected to Discord as %s#%s!",
             event->user->username, event->user->discriminator);
}

void
done_get_users(struct discord *client,
               struct discord_response *resp,
               const struct discord_users *users)
{
    const struct discord_message *event = resp->keep;
    char text[2000];

    if (!users->size) {
        snprintf(text, sizeof(text), "Nobody reacted with that emoji!");
    }
    else {
        char *cur = text;
        char *end = &text[sizeof(text) - 1];

        for (int i = 0; i < users->size; ++i) {
            cur += snprintf(cur, end - cur, "%s (%" PRIu64 ")\n",
                            users->array[i].username, users->array[i].id);

            if (cur >= end) break;
        }
    }

    struct discord_create_message params = { .content = text };
    discord_create_message(client, event->channel_id, &params, NULL);
}

void
fail_get_users(struct discord *client, struct discord_response *resp)
{
    const struct discord_message *event = resp->keep;
    char text[256];

    snprintf(text, sizeof(text), "Couldn't fetch reactions: %s",
             discord_strerror(resp->code, client));

    struct discord_create_message params = { .content = text };
    discord_create_message(client, event->channel_id, &params, NULL);
}

void
on_get_users(struct discord *client, const struct discord_message *event)
{
    if (event->author->bot || !event->referenced_message) return;

    struct discord_ret_users ret = {
        .done = &done_get_users,
        .fail = &fail_get_users,
        .keep = event,
    };
    struct discord_get_reactions params = { .limit = 25 };

    discord_get_reactions(client, event->channel_id,
                          event->referenced_message->id, 0, event->content,
                          &params, &ret);
}

void
on_create(struct discord *client, const struct discord_message *event)
{
    if (event->author->bot || !event->referenced_message) return;

    discord_create_reaction(client, event->referenced_message->channel_id,
                            event->referenced_message->id, 0, event->content,
                            NULL);
}

void
on_delete(struct discord *client, const struct discord_message *event)
{
    if (event->author->bot || !event->referenced_message) return;

    discord_delete_all_reactions_for_emoji(
        client, event->referenced_message->channel_id,
        event->referenced_message->id, 0, event->content, NULL);
}

void
on_delete_all(struct discord *client, const struct discord_message *event)
{
    if (event->author->bot || !event->referenced_message) return;

    discord_delete_all_reactions(client, event->referenced_message->channel_id,
                                 event->referenced_message->id, NULL);
}

void
on_delete_self(struct discord *client, const struct discord_message *event)
{
    if (event->author->bot || !event->referenced_message) return;

    discord_delete_own_reaction(client, event->referenced_message->channel_id,
                                event->referenced_message->id, 0,
                                event->content, NULL);
}

void
on_delete_user(struct discord *client, const struct discord_message *event)
{
    if (event->author->bot || !event->referenced_message) return;

    u64snowflake user_id = 0;
    char emoji_name[256] = "";

    sscanf(event->content, "%" SCNu64 " %s", &user_id, emoji_name);

    discord_delete_user_reaction(client, event->referenced_message->channel_id,
                                 event->referenced_message->id, user_id, 0,
                                 emoji_name, NULL);
}

int
main(int argc, char *argv[])
{
    const char *config_file;
    if (argc > 1)
        config_file = argv[1];
    else
        config_file = "../config.json";

    ccord_global_init();
    struct discord *client = discord_config_init(config_file);
    assert(NULL != client && "Couldn't initialize client");

    discord_set_on_ready(client, &on_ready);

    discord_set_prefix(client, "reaction.");
    discord_set_on_command(client, "get_users", &on_get_users);
    discord_set_on_command(client, "create", &on_create);
    discord_set_on_command(client, "delete", &on_delete);
    discord_set_on_command(client, "delete_all", &on_delete_all);
    discord_set_on_command(client, "delete_self", &on_delete_self);
    discord_set_on_command(client, "delete_user", &on_delete_user);

    print_usage();
    fgetc(stdin); // wait for input

    discord_run(client);

    discord_cleanup(client);
    ccord_global_cleanup();
}