use serde::Deserialize;

/// Gateway configuration, loaded from environment variables with BASCULE_ prefix.
#[derive(Debug, Deserialize)]
pub struct BasculeConfig {
    /// gRPC listen address (default: 0.0.0.0:50052)
    #[serde(default = "default_listen_addr")]
    pub listen_addr: String,

    /// OIDC issuer URL for token validation
    #[serde(default = "default_oidc_issuer")]
    pub oidc_issuer: String,

    /// Expected OIDC audience (client_id)
    #[serde(default = "default_oidc_audience")]
    pub oidc_audience: String,

    /// Default session lifetime in seconds for self-grant ceremonies
    #[serde(default = "default_session_lifetime")]
    pub session_lifetime_secs: u64,

    // --- Database (QM-provisioned bascule_svc credentials) ---
    #[serde(default = "default_db_host")]
    pub db_host: String,

    #[serde(default = "default_db_port")]
    pub db_port: u16,

    #[serde(default = "default_db_name")]
    pub db_name: String,

    #[serde(default = "default_db_user")]
    pub db_user: String,

    #[serde(default)]
    pub db_password: String,

    // --- OPA sidecar ---
    #[serde(default = "default_opa_url")]
    pub opa_url: String,

    // --- Quartermaster endpoint ---
    #[serde(default = "default_qm_endpoint")]
    pub qm_endpoint: String,

    // --- Accord ---
    #[serde(default = "default_accord_path")]
    pub accord_path: String,

    // --- Audit pipeline ---
    #[serde(default = "default_audit_batch_size")]
    pub audit_batch_size: usize,

    #[serde(default = "default_audit_flush_interval")]
    pub audit_flush_interval_secs: u64,
}

fn default_listen_addr() -> String {
    "0.0.0.0:50052".to_string()
}

fn default_oidc_issuer() -> String {
    "http://localhost:8080/realms/guildhouse".to_string()
}

fn default_oidc_audience() -> String {
    "bascule-gateway".to_string()
}

fn default_session_lifetime() -> u64 {
    28800 // 8 hours
}

fn default_db_host() -> String {
    "localhost".to_string()
}

fn default_db_port() -> u16 {
    5432
}

fn default_db_name() -> String {
    "telemetry".to_string()
}

fn default_db_user() -> String {
    "bascule_svc".to_string()
}

fn default_opa_url() -> String {
    "http://localhost:8181".to_string()
}

fn default_qm_endpoint() -> String {
    "http://quartermaster.quartermaster.svc.cluster.local:50051".to_string()
}

fn default_accord_path() -> String {
    "/accord/accord.yaml".to_string()
}

fn default_audit_batch_size() -> usize {
    50
}

fn default_audit_flush_interval() -> u64 {
    10
}

impl BasculeConfig {
    pub fn from_env() -> anyhow::Result<Self> {
        let config = config::Config::builder()
            .add_source(
                config::Environment::with_prefix("BASCULE")
                    .separator("__")
                    .try_parsing(true),
            )
            .set_default("listen_addr", default_listen_addr())?
            .set_default("oidc_issuer", default_oidc_issuer())?
            .set_default("oidc_audience", default_oidc_audience())?
            .set_default("session_lifetime_secs", default_session_lifetime() as i64)?
            .set_default("db_host", default_db_host())?
            .set_default("db_port", default_db_port() as i64)?
            .set_default("db_name", default_db_name())?
            .set_default("db_user", default_db_user())?
            .set_default("db_password", "")?
            .set_default("opa_url", default_opa_url())?
            .set_default("qm_endpoint", default_qm_endpoint())?
            .set_default("accord_path", default_accord_path())?
            .set_default("audit_batch_size", default_audit_batch_size() as i64)?
            .set_default("audit_flush_interval_secs", default_audit_flush_interval() as i64)?
            .build()?;

        Ok(config.try_deserialize()?)
    }

    /// HTTP listen address for ceremony approval endpoints.
    pub fn http_listen_addr(&self) -> String {
        std::env::var("BASCULE__HTTP_LISTEN_ADDR").unwrap_or_else(|_| "0.0.0.0:8443".to_string())
    }

    /// Build a PostgreSQL connection URL from the individual config fields.
    pub fn database_url(&self) -> String {
        format!(
            "postgresql://{}:{}@{}:{}/{}",
            self.db_user, self.db_password, self.db_host, self.db_port, self.db_name
        )
    }
}