use std::collections::HashMap;
use std::env;
use std::path::PathBuf;

#[derive(Debug, Clone)]
pub struct Config {
    pub gateway_id: String,
    pub farm_id: String,
    pub gateway_token: String,
    pub uplink_url: String,
    pub go2rtc_bin: String,
    pub go2rtc_config: String,
    /// Path to the fleet config file - see `fleet.rs` and
    /// `printers.example.toml` for the shape.
    pub printers_path: String,

    /// Per-printer CA certificate overrides, keyed by printer ID. Most
    /// Bambu printers chain to the bundled shared CA (`certs/bambu_ca2.pem`)
    /// and don't need an entry here - but some models (P1P, at least) ship
    /// their own certificate instead of one signed by that shared CA, with
    /// no single file covering all of them. Look up a printer's own entry
    /// (if any) when constructing it; there's no fleet-wide "the" override.
    pub bambu_ca_cert_overrides: HashMap<String, PathBuf>,
    /// When `false`, Bambu MQTTS connections skip certificate verification
    /// entirely instead of checking against a CA. `true` (the default) is
    /// the secure choice; only flip this fleet-wide policy if you have
    /// printers you can't get to verify any other way.
    pub bambu_require_valid_cert: bool,
}

impl Config {
    pub fn from_env() -> anyhow::Result<Self> {
        Ok(Self {
            gateway_id: require("CONTINUUM_GATEWAY_ID")?,
            farm_id: require("CONTINUUM_FARM_ID")?,
            gateway_token: require("CONTINUUM_GATEWAY_TOKEN")?,
            uplink_url: env_or("CONTINUUM_UPLINK_URL", "wss://api.continuum.local/ws/edge/v1"),
            go2rtc_bin: env_or("CONTINUUM_GO2RTC_BIN", "go2rtc"),
            go2rtc_config: env_or("CONTINUUM_GO2RTC_CONFIG", "./go2rtc.yaml"),
            printers_path: env_or("CONTINUUM_PRINTERS_PATH", "printers.toml"),

            bambu_ca_cert_overrides: parse_cert_overrides(&env_or("CONTINUUM_BAMBU_CA_CERT_OVERRIDES", "")),
            bambu_require_valid_cert: env_or("CONTINUUM_BAMBU_REQUIRE_VALID_CERT", "true") == "true",
        })
    }
}

/// Parses `"printer_id=path,printer_id2=path2"` into a lookup map. Empty
/// input (the common case - no overrides needed) yields an empty map.
fn parse_cert_overrides(raw: &str) -> HashMap<String, PathBuf> {
    raw.split(',')
        .filter_map(|entry| entry.split_once('='))
        .map(|(id, path)| (id.trim().to_string(), PathBuf::from(path.trim())))
        .collect()
}

fn require(key: &str) -> anyhow::Result<String> {
    env::var(key).map_err(|_| anyhow::anyhow!("missing required env var {key}"))
}

fn env_or(key: &str, default: &str) -> String {
    env::var(key).unwrap_or_else(|_| default.to_string())
}