//! FIPS daemon config + key materialisation.
//!
//! Writes `/etc/fips/fips.yaml`, `/etc/fips/fips.key`, and
//! `/etc/fips/fips.pub` from the archipelago node's seed-derived FIPS
//! keypair, then chmod 0600 the private key.
//!
//! Privileged filesystem writes go through a `sudo install` invocation
//! rather than opening `/etc/fips/*` directly — the archipelago service
//! user cannot write `/etc` itself. The sudoers policy in the ISO
//! whitelists `install` into `/etc/fips/`.

use anyhow::{Context, Result};
use serde::Serialize;
use std::path::Path;
use tokio::process::Command;

use super::{
    DAEMON_CONFIG_PATH, DAEMON_KEY_PATH, DAEMON_PUB_PATH, DEFAULT_TCP_PORT, PUBLISHED_UDP_PORT,
};

/// Header prepended to the generated YAML. serde doesn't emit comments, so
/// this is concatenated onto the serialised body.
const CONFIG_HEADER: &str = "# Generated by archipelago — do not edit by hand.\n\
                             # Regenerated on every key change and daemon upgrade.\n";

/// Typed mirror of the subset of upstream `fips.yaml` that archipelago owns.
///
/// This was previously built by `format!`-ing a string literal. Upstream's
/// config structs are `#[serde(deny_unknown_fields)]`, so a key we get wrong
/// doesn't degrade gracefully — the daemon refuses to start and the node drops
/// off the mesh. Serialising from typed structs lets the compiler and the
/// tests below catch drift, instead of a node discovering it at boot after an
/// upgrade.
///
/// Schema verified field-by-field against jmcorgan/fips **v0.4.1** (2026-07-20).
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct FipsConfig {
    pub node: NodeSection,
    pub tun: TunSection,
    pub dns: DnsSection,
    pub transports: TransportsSection,
    /// Static peers. Always empty: archipelago feeds peers dynamically via the
    /// seed-anchors apply loop and federation-invite hooks.
    pub peers: Vec<PeerEntry>,
}

#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct NodeSection {
    pub identity: IdentitySection,
    pub discovery: DiscoverySection,
    pub retry: RetrySection,
    pub rate_limit: RateLimitSection,
}

/// Fast-reconnect profile (`node.retry.*`). Upstream defaults (5s base
/// doubling to 300s) are tuned for stable always-on links; a node redialing
/// a recycled anchor sat off-mesh for ~90s. Field names verified live on
/// 2026-07-24: a daemon restarted with these keys in fips.yaml and peered.
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct RetrySection {
    pub base_interval_secs: u64,
    pub max_backoff_secs: u64,
    pub max_retries: u32,
}

/// Session-handshake resend pacing (`node.rate_limit.*`). Stock 1s x2.0
/// gaps out to 8-16s between resends exactly when a route has just
/// appeared; 400ms x1.5 keeps continuous coverage through the connect
/// window (phone measured session-after-route: 225ms).
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct RateLimitSection {
    pub handshake_resend_interval_ms: u64,
    pub handshake_resend_backoff: f64,
    pub handshake_max_resends: u32,
}

#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct IdentitySection {
    /// With `persistent: true` the daemon reuses the key file at
    /// config-dir/fips.key (= `DAEMON_KEY_PATH`) instead of generating an
    /// ephemeral identity on every start.
    pub persistent: bool,
}

#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct DiscoverySection {
    /// Lookup completion timeout. Lookups fired while the tree position is
    /// still settling are doomed; failing them fast (5s, not 10s) lets the
    /// 1s-backoff retry find the route the moment it exists.
    pub timeout_secs: u64,
    pub backoff_base_secs: u64,
    pub backoff_max_secs: u64,
    pub retry_interval_secs: u64,
    pub max_attempts: u8,
    pub lan: LanDiscoverySection,
}

/// mDNS / DNS-SD discovery on the local link (`node.discovery.lan.*`), added
/// upstream in v0.4.0 and opt-in there (upstream default is `false`).
///
/// We enable it so co-located nodes peer directly instead of depending on the
/// public anchor being reachable — an anchor blackhole on one network segment
/// otherwise islands a node completely.
///
/// Emitted unconditionally rather than version-gated: v0.3.0's `DiscoveryConfig`
/// has no `lan` field *and* no `deny_unknown_fields`, so a v0.3.0 daemon ignores
/// this key harmlessly (verified against the v0.3.0 source). It therefore starts
/// working on its own when a node upgrades, with no second config migration.
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct LanDiscoverySection {
    pub enabled: bool,
}

#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct TunSection {
    pub enabled: bool,
    pub name: String,
    pub mtu: u16,
}

#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct DnsSection {
    pub enabled: bool,
    pub bind_addr: String,
}

/// Both UDP and TCP are enabled: the public anchor answers on TCP/8443 only,
/// and networks that block outbound UDP can still bootstrap over TCP.
/// Upstream dropped the `tor:` transport variant — archipelago's own Tor
/// fallback handles that layer.
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct TransportsSection {
    pub udp: TransportBind,
    pub tcp: TransportBind,
}

#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct TransportBind {
    /// Upstream takes `bind_addr` ("host:port"), not `enabled` + `port`.
    pub bind_addr: String,
}

/// A static peer entry. Never constructed today (see `FipsConfig::peers`), but
/// typed so the shape is checked if static peering is ever needed.
#[derive(Debug, Clone, PartialEq, Serialize)]
pub struct PeerEntry {
    pub npub: String,
    pub address: String,
    pub transport: String,
}

impl Default for FipsConfig {
    fn default() -> Self {
        Self {
            node: NodeSection {
                identity: IdentitySection { persistent: true },
                discovery: DiscoverySection {
                    timeout_secs: 5,
                    backoff_base_secs: 1,
                    backoff_max_secs: 30,
                    retry_interval_secs: 2,
                    max_attempts: 3,
                    lan: LanDiscoverySection { enabled: true },
                },
                retry: RetrySection {
                    base_interval_secs: 1,
                    max_backoff_secs: 30,
                    max_retries: 30,
                },
                rate_limit: RateLimitSection {
                    handshake_resend_interval_ms: 400,
                    handshake_resend_backoff: 1.5,
                    handshake_max_resends: 10,
                },
            },
            tun: TunSection {
                enabled: true,
                name: "fips0".to_string(),
                mtu: 1280,
            },
            dns: DnsSection {
                enabled: true,
                bind_addr: "127.0.0.1".to_string(),
            },
            transports: TransportsSection {
                udp: TransportBind {
                    bind_addr: format!("0.0.0.0:{PUBLISHED_UDP_PORT}"),
                },
                tcp: TransportBind {
                    bind_addr: format!("0.0.0.0:{DEFAULT_TCP_PORT}"),
                },
            },
            peers: Vec::new(),
        }
    }
}

/// Render the FIPS daemon config. Overwrites any existing file — callers
/// re-run this whenever the key or daemon version changes.
///
/// Node identity comes from the key file on disk; the static peer list stays
/// empty because peers are fed dynamically at runtime.
pub fn render_config_yaml() -> String {
    let body = serde_yaml::to_string(&FipsConfig::default())
        .expect("FipsConfig is a plain struct tree and cannot fail to serialise");
    format!("{CONFIG_HEADER}{body}")
}

/// Install the local FIPS key + rendered config into `/etc/fips/`.
/// Requires the seed-derived key to already exist at `identity_dir/fips_key`.
pub async fn install(identity_dir: &Path) -> Result<()> {
    let src_key = identity_dir.join("fips_key");
    let src_pub = identity_dir.join("fips_key.pub");
    if !src_key.exists() {
        anyhow::bail!(
            "FIPS key not materialised at {} — run seed onboarding first",
            src_key.display()
        );
    }

    // Ensure /etc/fips exists with mode 0755.
    sudo_install_dir("/etc/fips").await?;

    // Render + write the yaml via a staging file the archipelago user owns,
    // then `sudo install` it into place so we never need to write to
    // /etc directly.
    let yaml = render_config_yaml();
    let stage = std::env::temp_dir().join(format!("fips-{}.yaml", std::process::id()));
    tokio::fs::write(&stage, yaml)
        .await
        .context("Failed to stage fips.yaml")?;
    let install_result = sudo_install_file(&stage, DAEMON_CONFIG_PATH, "0644").await;
    let _ = tokio::fs::remove_file(&stage).await;
    install_result?;

    // The release-hardening firewall (/etc/fips/fips.nft, provisioned
    // out-of-band) default-denies inbound on fips0 — without an explicit
    // allowance the node's web UI is unreachable over the mesh (phones got
    // RST on :80 with a healthy session; root-caused 2026-07-26 on
    // framework-pt). Ship the allowance as a fips.d drop-in on every
    // install/upgrade so no node ever regresses to a UI-less mesh.
    sudo_install_dir("/etc/fips/fips.d").await?;
    // PEER_PORT (5679) carries ALL federation sync, cloud browse/download,
    // mesh envelopes, DWN and invoices. It was missing from this allowlist
    // while the comment claimed "web UI + peer API" — so every hardened
    // node silently dropped peers' FIPS dials at the firewall and the whole
    // fleet fell back to Tor (root-caused live 2026-07-27: 28k drops on
    // .198's counter; :5679 answered in 0.35s once the rule was inserted).
    let dropin = format!(
        "# Written by archipelago on every daemon config install.\n\
         # Allows the web UI + peer API through the fips0\n\
         # default-deny inbound baseline (fips.nft).\n\
         tcp dport 80 accept\n\
         tcp dport 8443 accept\n\
         tcp dport {peer_port} accept\n",
        peer_port = crate::fips::dial::PEER_PORT
    );
    let nft_stage = std::env::temp_dir().join(format!("fips-webui-{}.nft", std::process::id()));
    tokio::fs::write(&nft_stage, dropin)
        .await
        .context("Failed to stage web-ui nft drop-in")?;
    let nft_install = sudo_install_file(&nft_stage, "/etc/fips/fips.d/80-web-ui.nft", "0644").await;
    let _ = tokio::fs::remove_file(&nft_stage).await;
    nft_install?;

    // App launch ports: the companion opens catalog apps by direct port
    // over the mesh. Ports of apps that aren't installed have no listener,
    // so the allowance is inert until an app exists to answer.
    let port_list = super::app_ports::APP_LAUNCH_PORTS
        .iter()
        .map(|p| p.to_string())
        .collect::<Vec<_>>()
        .join(", ");
    let app_dropin = format!(
        "# Written by archipelago on every daemon config install.\n\
         # Catalog app launch ports (web UIs) allowed through the fips0\n\
         # default-deny inbound baseline. Service/RPC ports stay closed.\n\
         tcp dport {{ {port_list} }} accept\n"
    );
    let app_stage = std::env::temp_dir().join(format!("fips-appports-{}.nft", std::process::id()));
    tokio::fs::write(&app_stage, app_dropin)
        .await
        .context("Failed to stage app-ports nft drop-in")?;
    let app_install =
        sudo_install_file(&app_stage, "/etc/fips/fips.d/85-app-ports.nft", "0644").await;
    let _ = tokio::fs::remove_file(&app_stage).await;
    app_install?;
    // Make the allowance live immediately; a no-op error when the
    // hardening baseline isn't installed on this node yet.
    if tokio::fs::try_exists("/etc/fips/fips.nft").await.unwrap_or(false) {
        match Command::new("sudo")
            .args(["nft", "-f", "/etc/fips/fips.nft"])
            .output()
            .await
        {
            Ok(out) if !out.status.success() => tracing::warn!(
                "nft reload after web-ui drop-in failed: {}",
                String::from_utf8_lossy(&out.stderr).trim()
            ),
            Err(e) => tracing::warn!("nft reload after web-ui drop-in failed: {e}"),
            _ => {}
        }
    }

    sudo_install_file(&src_key, DAEMON_KEY_PATH, "0600").await?;
    // Heal a legacy fips_key.pub that was written as bech32 npub text
    // (pre-fix identity::write_fips_key_from_seed did this). Upstream
    // fips expects 32 raw bytes; a text file silently passes through
    // and then the daemon can't identify itself to peers. This
    // rewrites the source file in place with the correct binary form
    // derived from fips_key before staging it to /etc/fips/fips.pub.
    normalize_pub_file(&src_key, &src_pub).await?;
    sudo_install_file(&src_pub, DAEMON_PUB_PATH, "0644").await?;

    Ok(())
}

/// Ensure `fips_key.pub` is 32 raw bytes. If it's a bech32 npub text
/// file (from the pre-fix writer), decode it and rewrite in place. If
/// the file is missing or its content doesn't match either format,
/// re-derive the public key from `fips_key` and write that.
pub async fn normalize_pub_file(key_path: &Path, pub_path: &Path) -> Result<()> {
    // Happy path: already 32 raw bytes.
    if let Ok(bytes) = tokio::fs::read(pub_path).await {
        if bytes.len() == 32 {
            return Ok(());
        }
        // bech32 npub text from the pre-fix writer: decode in place.
        if let Ok(s) = std::str::from_utf8(&bytes) {
            let trimmed = s.trim();
            if trimmed.starts_with("npub1") {
                if let Ok(pk) = nostr_sdk::PublicKey::parse(trimmed) {
                    let raw: [u8; 32] = pk.to_bytes();
                    tokio::fs::write(pub_path, raw)
                        .await
                        .context("rewriting fips_key.pub as 32 raw bytes")?;
                    tracing::info!(
                        "Migrated legacy bech32 fips_key.pub to raw-byte form at {}",
                        pub_path.display()
                    );
                    return Ok(());
                }
            }
        }
    }

    // Fallback: no pub file, or unreadable format. Re-derive from the
    // private key file (already validated by load_fips_keys).
    let secret_bytes = tokio::fs::read(key_path)
        .await
        .with_context(|| format!("read {} to derive public", key_path.display()))?;
    let text = std::str::from_utf8(&secret_bytes)
        .context("fips_key is not UTF-8 — can't derive public")?;
    let secret = nostr_sdk::SecretKey::parse(text.trim())
        .context("fips_key not parseable as bech32 nsec")?;
    let keys = nostr_sdk::Keys::new(secret);
    let raw: [u8; 32] = keys.public_key().to_bytes();
    tokio::fs::write(pub_path, raw)
        .await
        .context("writing re-derived fips_key.pub")?;
    tracing::info!("Re-derived fips_key.pub from fips_key");
    Ok(())
}

async fn sudo_install_dir(path: &str) -> Result<()> {
    let out = Command::new("sudo")
        .args(["install", "-d", "-m", "0755", path])
        .output()
        .await
        .with_context(|| format!("sudo install -d {}", path))?;
    if !out.status.success() {
        anyhow::bail!(
            "sudo install -d {}: {}",
            path,
            String::from_utf8_lossy(&out.stderr).trim()
        );
    }
    Ok(())
}

async fn sudo_install_file(src: &Path, dest: &str, mode: &str) -> Result<()> {
    let out = Command::new("sudo")
        .args([
            "install",
            "-m",
            mode,
            src.to_str().context("Non-UTF8 source path")?,
            dest,
        ])
        .output()
        .await
        .with_context(|| format!("sudo install {} -> {}", src.display(), dest))?;
    if !out.status.success() {
        anyhow::bail!(
            "sudo install {} -> {}: {}",
            src.display(),
            dest,
            String::from_utf8_lossy(&out.stderr).trim()
        );
    }
    Ok(())
}

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

    #[test]
    fn test_rendered_yaml_matches_upstream_schema() {
        let yaml = render_config_yaml();
        assert!(yaml.contains("persistent: true"));
        assert!(yaml.contains(&format!("0.0.0.0:{}", PUBLISHED_UDP_PORT)));
        assert!(yaml.contains(&format!("0.0.0.0:{}", DEFAULT_TCP_PORT)));
        assert!(yaml.contains("udp:"));
        assert!(yaml.contains("tcp:"));
        assert!(yaml.contains("tun:"));
        assert!(yaml.contains("name: fips0"));
        // Upstream fips dropped the `tor:` transport variant; archipelago
        // handles Tor fallback itself. Make sure we didn't regress.
        assert!(!yaml.contains("tor:"));
    }

    /// Exact-output snapshot. Upstream's config structs are
    /// `deny_unknown_fields`, so an accidental key rename/addition means the
    /// daemon won't start. Pinning the full rendering makes any such change
    /// fail here — where it's cheap — instead of on a node after an upgrade.
    /// If this fails, re-verify against the upstream schema before updating it.
    #[test]
    fn test_rendered_yaml_exact_snapshot() {
        let expected = "\
# Generated by archipelago — do not edit by hand.
# Regenerated on every key change and daemon upgrade.
node:
  identity:
    persistent: true
  discovery:
    timeout_secs: 5
    backoff_base_secs: 1
    backoff_max_secs: 30
    retry_interval_secs: 2
    max_attempts: 3
    lan:
      enabled: true
  retry:
    base_interval_secs: 1
    max_backoff_secs: 30
    max_retries: 30
  rate_limit:
    handshake_resend_interval_ms: 400
    handshake_resend_backoff: 1.5
    handshake_max_resends: 10
tun:
  enabled: true
  name: fips0
  mtu: 1280
dns:
  enabled: true
  bind_addr: 127.0.0.1
transports:
  udp:
    bind_addr: 0.0.0.0:2121
  tcp:
    bind_addr: 0.0.0.0:8443
peers: []
";
        assert_eq!(render_config_yaml(), expected);
    }

    /// The rendered config must parse as YAML and carry the mDNS opt-in at the
    /// exact path upstream reads (`node.discovery.lan.enabled`) — a typo there
    /// would silently leave LAN discovery off rather than erroring.
    #[test]
    fn test_lan_discovery_enabled_at_upstream_path() {
        let yaml = render_config_yaml();
        let parsed: serde_yaml::Value = serde_yaml::from_str(&yaml).expect("renders valid YAML");
        assert_eq!(
            parsed["node"]["discovery"]["lan"]["enabled"],
            serde_yaml::Value::Bool(true),
        );
    }

    /// Rendering is deterministic: the startup drift check in server.rs compares
    /// the freshly rendered config against what's on disk, so any instability
    /// here would cause an endless reinstall+restart loop of the daemon.
    #[test]
    fn test_render_is_deterministic() {
        assert_eq!(render_config_yaml(), render_config_yaml());
    }

    #[tokio::test]
    async fn test_install_refuses_when_key_missing() {
        let dir = tempfile::tempdir().unwrap();
        let err = install(dir.path()).await.unwrap_err();
        assert!(err.to_string().contains("FIPS key not materialised"));
    }
}