//! Configuration file and settings management
use config::{Config, ConfigError, File};
use serde::{Deserialize, Serialize};
use std::time::Duration;
use tracing::warn;

#[derive(Debug, Serialize, Deserialize, Clone)]
#[allow(unused)]
pub struct Info {
    pub relay_url: Option<String>,
    pub name: Option<String>,
    pub description: Option<String>,
    pub pubkey: Option<String>,
    pub contact: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Database {
    pub data_directory: String,
    pub engine: String,
    pub in_memory: bool,
    pub min_conn: u32,
    pub max_conn: u32,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Network {
    pub port: u16,
    pub address: String,
    pub remote_ip_header: Option<String>, // retrieve client IP from this HTTP header if present
    pub ping_interval_seconds: u32,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Options {
    pub reject_future_seconds: Option<usize>, // if defined, reject any events with a timestamp more than X seconds in the future
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Retention {
    // TODO: implement
    pub max_events: Option<usize>,                // max events
    pub max_bytes: Option<usize>,                 // max size
    pub persist_days: Option<usize>,              // oldest message
    pub whitelist_addresses: Option<Vec<String>>, // whitelisted addresses (never delete)
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Limits {
    pub messages_per_sec: Option<u32>, // Artificially slow down event writing to limit disk consumption (averaged over 1 minute)
    pub subscriptions_per_min: Option<u32>, // Artificially slow down request (db query) creation to prevent abuse (averaged over 1 minute)
    pub db_conns_per_client: Option<u32>, // How many concurrent database queries (not subscriptions) may a client have?
    pub max_blocking_threads: usize,
    pub max_event_bytes: Option<usize>, // Maximum size of an EVENT message
    pub max_ws_message_bytes: Option<usize>,
    pub max_ws_frame_bytes: Option<usize>,
    pub broadcast_buffer: usize, // events to buffer for subscribers (prevents slow readers from consuming memory)
    pub event_persist_buffer: usize, // events to buffer for database commits (block senders if database writes are too slow)
    pub event_kind_blacklist: Option<Vec<u64>>
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Authorization {
    pub pubkey_whitelist: Option<Vec<String>>, // If present, only allow these pubkeys to publish events
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Diagnostics {
    pub tracing: bool, // enables tokio console-subscriber
}

#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Clone, Copy)]
#[serde(rename_all = "lowercase")]
pub enum VerifiedUsersMode {
    Enabled,
    Passive,
    Disabled,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct VerifiedUsers {
    pub mode: VerifiedUsersMode, // Mode of operation: "enabled" (enforce) or "passive" (check only). If none, this is simply disabled.
    pub domain_whitelist: Option<Vec<String>>, // If present, only allow verified users from these domains can publish events
    pub domain_blacklist: Option<Vec<String>>, // If present, allow all verified users from any domain except these
    pub verify_expiration: Option<String>, // how long a verification is cached for before no longer being used
    pub verify_update_frequency: Option<String>, // how often to attempt to update verification
    pub verify_expiration_duration: Option<Duration>, // internal result of parsing verify_expiration
    pub verify_update_frequency_duration: Option<Duration>, // internal result of parsing verify_update_frequency
    pub max_consecutive_failures: usize, // maximum number of verification failures in a row, before ceasing future checks
}

impl VerifiedUsers {
    pub fn init(&mut self) {
        self.verify_expiration_duration = self.verify_expiration_duration();
        self.verify_update_frequency_duration = self.verify_update_duration();
    }

    #[must_use]
    pub fn is_enabled(&self) -> bool {
        self.mode == VerifiedUsersMode::Enabled
    }

    #[must_use]
    pub fn is_active(&self) -> bool {
        self.mode == VerifiedUsersMode::Enabled || self.mode == VerifiedUsersMode::Passive
    }

    #[must_use]
    pub fn is_passive(&self) -> bool {
        self.mode == VerifiedUsersMode::Passive
    }

    #[must_use]
    pub fn verify_expiration_duration(&self) -> Option<Duration> {
        self.verify_expiration
            .as_ref()
            .and_then(|x| parse_duration::parse(x).ok())
    }

    #[must_use]
    pub fn verify_update_duration(&self) -> Option<Duration> {
        self.verify_update_frequency
            .as_ref()
            .and_then(|x| parse_duration::parse(x).ok())
    }

    #[must_use]
    pub fn is_valid(&self) -> bool {
        self.verify_expiration_duration().is_some() && self.verify_update_duration().is_some()
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[allow(unused)]
pub struct Settings {
    pub info: Info,
    pub diagnostics: Diagnostics,
    pub database: Database,
    pub network: Network,
    pub limits: Limits,
    pub authorization: Authorization,
    pub verified_users: VerifiedUsers,
    pub retention: Retention,
    pub options: Options,
}

impl Settings {
    #[must_use]
    pub fn new() -> Self {
        let default_settings = Self::default();
        // attempt to construct settings with file
        let from_file = Self::new_from_default(&default_settings);
        match from_file {
            Ok(f) => f,
            Err(e) => {
                warn!("Error reading config file ({:?})", e);
                default_settings
            }
        }
    }

    fn new_from_default(default: &Settings) -> Result<Self, ConfigError> {
        let builder = Config::builder();
        let config: Config = builder
            // use defaults
            .add_source(Config::try_from(default)?)
            // override with file contents
            .add_source(File::with_name("config.toml"))
            .build()?;
        let mut settings: Settings = config.try_deserialize()?;
        // ensure connection pool size is logical
        assert!(
            settings.database.min_conn <= settings.database.max_conn,
            "Database min_conn setting ({}) cannot exceed max_conn ({})",
            settings.database.min_conn,
            settings.database.max_conn
        );
        // ensure durations parse
        assert!(
            settings.verified_users.is_valid(),
            "VerifiedUsers time settings could not be parsed"
        );
        // initialize durations for verified users
        settings.verified_users.init();
        Ok(settings)
    }
}

impl Default for Settings {
    fn default() -> Self {
        Settings {
            info: Info {
                relay_url: None,
                name: Some("Unnamed nostr-rs-relay".to_owned()),
                description: None,
                pubkey: None,
                contact: None,
            },
            diagnostics: Diagnostics { tracing: false },
            database: Database {
                data_directory: ".".to_owned(),
		engine: "sqlite".to_owned(),
                in_memory: false,
                min_conn: 4,
                max_conn: 8,
            },
            network: Network {
                port: 8080,
                ping_interval_seconds: 300,
                address: "0.0.0.0".to_owned(),
                remote_ip_header: None,
            },
            limits: Limits {
                messages_per_sec: None,
                subscriptions_per_min: None,
                db_conns_per_client: None,
                max_blocking_threads: 16,
                max_event_bytes: Some(2 << 17),      // 128K
                max_ws_message_bytes: Some(2 << 17), // 128K
                max_ws_frame_bytes: Some(2 << 17),   // 128K
                broadcast_buffer: 16384,
                event_persist_buffer: 4096,
                event_kind_blacklist: None,
            },
            authorization: Authorization {
                pubkey_whitelist: None, // Allow any address to publish
            },
            verified_users: VerifiedUsers {
                mode: VerifiedUsersMode::Disabled,
                domain_whitelist: None,
                domain_blacklist: None,
                verify_expiration: Some("1 week".to_owned()),
                verify_update_frequency: Some("1 day".to_owned()),
                verify_expiration_duration: None,
                verify_update_frequency_duration: None,
                max_consecutive_failures: 20,
            },
            retention: Retention {
                max_events: None,          // max events
                max_bytes: None,           // max size
                persist_days: None,        // oldest message
                whitelist_addresses: None, // whitelisted addresses (never delete)
            },
            options: Options {
                reject_future_seconds: None, // Reject events in the future if defined
            },
        }
    }
}