reminder-bot/src/framework.rs

use async_trait::async_trait;

use serenity::{
    client::Context,
    constants::MESSAGE_CODE_LIMIT,
    framework::{standard::CommandResult, Framework},
    futures::prelude::future::BoxFuture,
    http::Http,
    model::{
        channel::{Channel, GuildChannel, Message},
        guild::{Guild, Member},
        id::ChannelId,
    },
    Result as SerenityResult,
};

use log::{error, info, warn};

use regex::{Match, Regex};

use std::{collections::HashMap, env, fmt};

use crate::{consts::PREFIX, models::ChannelData, SQLPool};

type CommandFn =
    for<'fut> fn(&'fut Context, &'fut Message, String) -> BoxFuture<'fut, CommandResult>;

#[derive(Debug, PartialEq)]
pub enum PermissionLevel {
    Unrestricted,
    Managed,
    Restricted,
}

pub struct Command {
    pub name: &'static str,
    pub required_perms: PermissionLevel,
    pub supports_dm: bool,
    pub can_blacklist: bool,
    pub func: CommandFn,
}

impl Command {
    async fn check_permissions(&self, ctx: &Context, guild: &Guild, member: &Member) -> bool {
        if self.required_perms == PermissionLevel::Unrestricted {
            true
        } else {
            for role_id in &member.roles {
                let role = role_id.to_role_cached(&ctx).await;

                if let Some(cached_role) = role {
                    if cached_role.permissions.manage_guild()
                        || (self.required_perms == PermissionLevel::Managed
                            && cached_role.permissions.manage_messages())
                    {
                        return true;
                    }
                }
            }

            if self.required_perms == PermissionLevel::Managed {
                let pool = ctx
                    .data
                    .read()
                    .await
                    .get::<SQLPool>()
                    .cloned()
                    .expect("Could not get SQLPool from data");

                match sqlx::query!(
                    "
SELECT
    role
FROM
    roles
INNER JOIN
    command_restrictions ON roles.id = command_restrictions.role_id
WHERE
    command_restrictions.command = ? AND
    roles.guild_id = (
        SELECT
            id
        FROM
            guilds
        WHERE
            guild = ?)
                    ",
                    self.name,
                    guild.id.as_u64()
                )
                .fetch_all(&pool)
                .await
                {
                    Ok(rows) => {
                        let role_ids = member
                            .roles
                            .iter()
                            .map(|r| *r.as_u64())
                            .collect::<Vec<u64>>();

                        for row in rows {
                            if role_ids.contains(&row.role) {
                                return true;
                            }
                        }

                        false
                    }

                    Err(sqlx::Error::RowNotFound) => false,

                    Err(e) => {
                        warn!(
                            "Unexpected error occurred querying command_restrictions: {:?}",
                            e
                        );

                        false
                    }
                }
            } else {
                false
            }
        }
    }
}

impl fmt::Debug for Command {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Command")
            .field("name", &self.name)
            .field("required_perms", &self.required_perms)
            .field("supports_dm", &self.supports_dm)
            .field("can_blacklist", &self.can_blacklist)
            .finish()
    }
}

// create event handler for bot
pub struct RegexFramework {
    commands: HashMap<String, &'static Command>,
    command_matcher: Regex,
    dm_regex_matcher: Regex,
    default_prefix: String,
    client_id: u64,
    ignore_bots: bool,
}

#[async_trait]
pub trait SendIterator {
    async fn say_lines(
        self,
        http: impl AsRef<Http> + Send + Sync + 'async_trait,
        content: impl Iterator<Item = String> + Send + 'async_trait,
    ) -> SerenityResult<()>;
}

#[async_trait]
impl SendIterator for ChannelId {
    async fn say_lines(
        self,
        http: impl AsRef<Http> + Send + Sync + 'async_trait,
        content: impl Iterator<Item = String> + Send + 'async_trait,
    ) -> SerenityResult<()> {
        let mut current_content = String::new();

        for line in content {
            if current_content.len() + line.len() > MESSAGE_CODE_LIMIT as usize {
                self.say(&http, &current_content).await?;

                current_content = line;
            } else {
                current_content = format!("{}\n{}", current_content, line);
            }
        }
        if !current_content.is_empty() {
            self.say(&http, &current_content).await?;
        }

        Ok(())
    }
}

impl RegexFramework {
    pub fn new<T: Into<u64>>(client_id: T) -> Self {
        Self {
            commands: HashMap::new(),
            command_matcher: Regex::new(r#"^$"#).unwrap(),
            dm_regex_matcher: Regex::new(r#"^$"#).unwrap(),
            default_prefix: env::var("DEFAULT_PREFIX").unwrap_or_else(|_| PREFIX.to_string()),
            client_id: client_id.into(),
            ignore_bots: true,
        }
    }

    pub fn default_prefix<T: ToString>(mut self, new_prefix: T) -> Self {
        self.default_prefix = new_prefix.to_string();

        self
    }

    pub fn ignore_bots(mut self, ignore_bots: bool) -> Self {
        self.ignore_bots = ignore_bots;

        self
    }

    pub fn add_command<S: ToString>(mut self, name: S, command: &'static Command) -> Self {
        self.commands.insert(name.to_string(), command);

        self
    }

    pub fn build(mut self) -> Self {
        {
            let command_names;

            {
                let mut command_names_vec =
                    self.commands.keys().map(|k| &k[..]).collect::<Vec<&str>>();

                command_names_vec.sort_unstable_by(|a, b| b.len().cmp(&a.len()));

                command_names = command_names_vec.join("|");
            }

            info!("Command names: {}", command_names);

            {
                let match_string = r#"^(?:(?:<@ID>\s+)|(?:<@!ID>\s+)|(?P<prefix>\S{1,5}?))(?P<cmd>COMMANDS)(?:$|\s+(?P<args>.*))$"#
                    .replace("COMMANDS", command_names.as_str())
                    .replace("ID", self.client_id.to_string().as_str());

                self.command_matcher = Regex::new(match_string.as_str()).unwrap();
            }
        }

        {
            let dm_command_names;

            {
                let mut command_names_vec = self
                    .commands
                    .iter()
                    .filter_map(|(key, command)| {
                        if command.supports_dm {
                            Some(&key[..])
                        } else {
                            None
                        }
                    })
                    .collect::<Vec<&str>>();

                command_names_vec.sort_unstable_by(|a, b| b.len().cmp(&a.len()));

                dm_command_names = command_names_vec.join("|");
            }

            {
                let match_string = r#"^(?:(?:<@ID>\s+)|(?:<@!ID>\s+)|(\$)|())(?P<cmd>COMMANDS)(?:$|\s+(?P<args>.*))$"#
                    .replace("COMMANDS", dm_command_names.as_str())
                    .replace("ID", self.client_id.to_string().as_str());

                self.dm_regex_matcher = Regex::new(match_string.as_str()).unwrap();
            }
        }

        self
    }
}

enum PermissionCheck {
    None,  // No permissions
    Basic, // Send + Embed permissions (sufficient to reply)
    All,   // Above + Manage Webhooks (sufficient to operate)
}

#[async_trait]
impl Framework for RegexFramework {
    async fn dispatch(&self, ctx: Context, msg: Message) {
        async fn check_self_permissions(
            ctx: &Context,
            guild: &Guild,
            channel: &GuildChannel,
        ) -> Result<PermissionCheck, Box<dyn std::error::Error + Sync + Send>> {
            let user_id = ctx.cache.current_user_id().await;

            let guild_perms = guild.member_permissions(user_id);
            let perms = channel.permissions_for_user(ctx, user_id).await?;

            let basic_perms = perms.send_messages() && perms.embed_links();

            Ok(if basic_perms && guild_perms.manage_webhooks() {
                PermissionCheck::All
            } else if basic_perms {
                PermissionCheck::Basic
            } else {
                PermissionCheck::None
            })
        }

        async fn check_prefix(ctx: &Context, guild: &Guild, prefix_opt: Option<Match<'_>>) -> bool {
            if let Some(prefix) = prefix_opt {
                let pool = ctx
                    .data
                    .read()
                    .await
                    .get::<SQLPool>()
                    .cloned()
                    .expect("Could not get SQLPool from data");

                match sqlx::query!(
                    "SELECT prefix FROM guilds WHERE guild = ?",
                    guild.id.as_u64()
                )
                .fetch_one(&pool)
                .await
                {
                    Ok(row) => prefix.as_str() == row.prefix,

                    Err(sqlx::Error::RowNotFound) => {
                        let _ = sqlx::query!(
                            "INSERT INTO guilds (guild, name) VALUES (?, ?)",
                            guild.id.as_u64(),
                            guild.name
                        )
                        .execute(&pool)
                        .await;

                        prefix.as_str() == "$"
                    }

                    Err(e) => {
                        warn!("Unexpected error in prefix query: {:?}", e);

                        false
                    }
                }
            } else {
                true
            }
        }

        // gate to prevent analysing messages unnecessarily
        if (msg.author.bot && self.ignore_bots)
            || msg.tts
            || msg.content.is_empty()
            || !msg.attachments.is_empty()
        {
        }
        // Guild Command
        else if let (Some(guild), Some(Channel::Guild(channel))) =
            (msg.guild(&ctx).await, msg.channel(&ctx).await)
        {
            let member = guild.member(&ctx, &msg.author).await.unwrap();

            if let Some(full_match) = self.command_matcher.captures(&msg.content[..]) {
                if check_prefix(&ctx, &guild, full_match.name("prefix")).await {
                    match check_self_permissions(&ctx, &guild, &channel).await {
                        Ok(perms) => match perms {
                            PermissionCheck::All => {
                                let pool = ctx
                                    .data
                                    .read()
                                    .await
                                    .get::<SQLPool>()
                                    .cloned()
                                    .expect("Could not get SQLPool from data");

                                let command = self
                                    .commands
                                    .get(full_match.name("cmd").unwrap().as_str())
                                    .unwrap();
                                let channel_data = ChannelData::from_channel(
                                    msg.channel(&ctx).await.unwrap(),
                                    &pool,
                                )
                                .await;

                                if !command.can_blacklist
                                    || !channel_data.map(|c| c.blacklisted).unwrap_or(false)
                                {
                                    let args = full_match
                                        .name("args")
                                        .map(|m| m.as_str())
                                        .unwrap_or("")
                                        .to_string();

                                    if command.check_permissions(&ctx, &guild, &member).await {
                                        (command.func)(&ctx, &msg, args).await.unwrap();
                                    } else if command.required_perms == PermissionLevel::Restricted
                                    {
                                        let _ = msg.channel_id.say(&ctx, "You must have permission level `Manage Server` or greater to use this command.").await;
                                    } else if command.required_perms == PermissionLevel::Managed {
                                        let _ = msg.channel_id.say(&ctx, "You must have `Manage Messages` or have a role capable of sending reminders to that channel. Please talk to your server admin, and ask them to use the `{prefix}restrict` command to specify allowed roles.").await;
                                    }
                                }
                            }

                            PermissionCheck::Basic => {
                                let _ = msg.channel_id.say(&ctx, "Not enough perms").await;
                            }

                            PermissionCheck::None => {
                                warn!("Missing enough permissions for guild {}", guild.id);
                            }
                        },

                        Err(e) => {
                            error!(
                                "Error occurred getting permissions in guild {}: {:?}",
                                guild.id, e
                            );
                        }
                    }
                }
            }
        }
        // DM Command
        else if let Some(full_match) = self.dm_regex_matcher.captures(&msg.content[..]) {
            let command = self
                .commands
                .get(full_match.name("cmd").unwrap().as_str())
                .unwrap();
            let args = full_match
                .name("args")
                .map(|m| m.as_str())
                .unwrap_or("")
                .to_string();

            (command.func)(&ctx, &msg, args).await.unwrap();
        }
    }
}