//! Server deployment configuration.
//!
//! Reads from environment variables to select adapter (local/redis/nats)
//! and WebTransport settings.

use std::env;

/// Adapter + message bus configuration for multi-node scale-out.
#[derive(Debug, Clone)]
pub struct DeployConfig {
    /// "local" | "redis" | "nats"
    pub adapter_mode: String,
    /// Redis URL for single-node Redis, e.g. `redis://localhost:6379`.
    pub redis_url: Option<String>,
    /// Whether Redis cluster mode is enabled.
    pub redis_cluster_enabled: bool,
    /// Redis cluster nodes, comma-separated host:port pairs.
    /// Example: "redis1:6379,redis2:6379,redis3:6379"
    pub redis_cluster_nodes: String,
    /// Redis password (optional).
    pub redis_password: String,
    /// NATS connection URL (used when adapter_mode = "nats").
    pub nats_url: String,
    /// Unique server ID for this node.
    pub server_id: String,
    /// Enable WebTransport server.
    pub webtransport_enabled: bool,
    /// WebTransport listen port.
    pub webtransport_port: u16,
    /// TLS certificate path (required for WebTransport).
    pub cert_path: String,
    /// TLS key path (required for WebTransport).
    pub key_path: String,
}

impl DeployConfig {
    pub fn from_env() -> Self {
        let server_id = env::var("IMKS_SERVER_ID").unwrap_or_else(|_| hostname());

        Self {
            adapter_mode: env::var("IMKS_ADAPTER").unwrap_or_else(|_| "local".into()),
            redis_url: env::var("IMKS_REDIS_URL")
                .ok()
                .or_else(|| env::var("APP_REDIS_URL").ok())
                .filter(|v| !v.trim().is_empty()),
            redis_cluster_enabled: env_bool("IMKS_REDIS_CLUSTER_ENABLED")
                .or_else(|| env_bool("APP_REDIS_CLUSTER_ENABLED"))
                .unwrap_or(false),
            redis_cluster_nodes: env::var("IMKS_REDIS_CLUSTER_NODES")
                .or_else(|_| env::var("APP_REDIS_CLUSTER_NODES"))
                .unwrap_or_default(),
            redis_password: env::var("IMKS_REDIS_PASSWORD")
                .or_else(|_| env::var("APP_REDIS_PASSWORD"))
                .unwrap_or_default(),
            nats_url: env::var("IMKS_NATS_URL").unwrap_or_else(|_| "nats://localhost:4222".into()),
            server_id,
            webtransport_enabled: env::var("IMKS_WT_ENABLED")
                .map(|v| v == "true" || v == "1")
                .unwrap_or(false),
            webtransport_port: env::var("IMKS_WT_PORT")
                .ok()
                .and_then(|v| v.parse().ok())
                .unwrap_or(3001),
            cert_path: env::var("IMKS_WT_CERT_PATH").unwrap_or_default(),
            key_path: env::var("IMKS_WT_KEY_PATH").unwrap_or_default(),
        }
    }

    /// Build a redis-rs compatible Redis URL.
    ///
    /// This mirrors appks:
    /// - cluster disabled: require `IMKS_REDIS_URL` or `APP_REDIS_URL`
    /// - cluster enabled: require `IMKS_REDIS_CLUSTER_NODES` or `APP_REDIS_CLUSTER_NODES`
    pub fn redis_url(&self) -> Result<String, String> {
        if self.redis_cluster_enabled {
            return self.redis_cluster_url();
        }

        self.redis_url.clone().ok_or_else(|| {
            "Redis cluster disabled but IMKS_REDIS_URL/APP_REDIS_URL is not set".into()
        })
    }

    /// Build a redis-cluster URL from cluster_nodes and optional password.
    ///
    /// Produces a redis-rs compatible URL in the format:
    /// `redis-cluster://[password@]host1:port1?node=host2:port2&node=host3:port3`
    ///
    /// The first node becomes the URL authority host:port; additional nodes
    /// are appended as `node` query parameters.
    pub fn redis_cluster_url(&self) -> Result<String, String> {
        let auth = if self.redis_password.is_empty() {
            String::new()
        } else {
            format!(":{}@", self.redis_password)
        };

        let nodes: Vec<String> = self
            .redis_cluster_nodes
            .split(',')
            .map(normalize_redis_cluster_node)
            .filter(|s| !s.is_empty())
            .collect();

        if nodes.is_empty() {
            return Err("Redis cluster enabled but IMKS_REDIS_CLUSTER_NODES/APP_REDIS_CLUSTER_NODES is empty".into());
        }

        if nodes.len() == 1 {
            return Ok(format!("redis-cluster://{}{}", auth, nodes[0]));
        }

        let mut url = format!("redis-cluster://{}{}", auth, nodes[0]);
        for (i, node) in nodes.iter().skip(1).enumerate() {
            url.push(if i == 0 { '?' } else { '&' });
            url.push_str(&format!("node={}", node));
        }
        Ok(url)
    }
}

impl Default for DeployConfig {
    fn default() -> Self {
        Self::from_env()
    }
}

fn env_bool(key: &str) -> Option<bool> {
    env::var(key).ok().map(|v| v == "true" || v == "1")
}

fn normalize_redis_cluster_node(node: &str) -> String {
    let trimmed = node.trim();
    let without_scheme = trimmed
        .strip_prefix("redis://")
        .or_else(|| trimmed.strip_prefix("rediss://"))
        .unwrap_or(trimmed);
    let without_auth = without_scheme
        .rsplit_once('@')
        .map(|(_, host)| host)
        .unwrap_or(without_scheme);
    without_auth
        .split('/')
        .next()
        .unwrap_or_default()
        .to_string()
}

fn hostname() -> String {
    env::var("HOSTNAME")
        .or_else(|_| env::var("HOST"))
        .unwrap_or_else(|_| "imks-node-1".into())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn normalize_cluster_nodes_accepts_appks_style_urls() {
        assert_eq!(
            normalize_redis_cluster_node("redis://127.0.0.1:6380"),
            "127.0.0.1:6380"
        );
        assert_eq!(
            normalize_redis_cluster_node("rediss://127.0.0.1:6381/0"),
            "127.0.0.1:6381"
        );
        assert_eq!(
            normalize_redis_cluster_node("redis://:secret@127.0.0.1:6382"),
            "127.0.0.1:6382"
        );
        assert_eq!(
            normalize_redis_cluster_node("127.0.0.1:6383"),
            "127.0.0.1:6383"
        );
    }

    #[test]
    fn redis_cluster_url_normalizes_nodes() {
        let config = DeployConfig {
            adapter_mode: "redis".into(),
            redis_url: None,
            redis_cluster_enabled: true,
            redis_cluster_nodes: "redis://127.0.0.1:6380,redis://127.0.0.1:6381".into(),
            redis_password: String::new(),
            nats_url: "nats://localhost:4222".into(),
            server_id: "test".into(),
            webtransport_enabled: false,
            webtransport_port: 3001,
            cert_path: String::new(),
            key_path: String::new(),
        };

        assert_eq!(
            config.redis_cluster_url().unwrap(),
            "redis-cluster://127.0.0.1:6380?node=127.0.0.1:6381"
        );
    }
}