//! `spectra connect` and the client configuration (spec §8.6): trust a

//! Spectra on another machine because the owner's own identity delegates

//! to its instance key and that key vouches for its certificate; pin the

//! certificate; claim a server set up with `spectra init --owner`.

use super::{identity, ui, Ctx};

use anyhow::{bail, Context, Result};

use oxy_core::identity::Identity;

use serde_json::Value as Json;

use spectra_core::daemon::WireEvent;

use spectra_core::keys::KeyPair;

use spectra_core::principals::{identity_payload, signed_event, DELEGATION_SCOPE};

use spectra_mcp::client::{host_port, Client, Endpoint};

use spectra_mcp::tls::Pinned;

use std::path::{Path, PathBuf};

/// The client configuration: which server, and what to trust there.

#[derive(Clone, Debug)]

pub struct ClientCfg {

    pub server: String,

    pub instance: String,

    pub tls_spki: [u8; 32],

}

impl ClientCfg {

    pub fn endpoint(&self) -> Result<Endpoint> {

        Endpoint::tls(&self.server, self.tls_spki)

    }

}

/// `SPECTRA_SERVER`, else `$XDG_CONFIG_HOME/spectra/client.toml`, else

/// `~/.config/spectra/client.toml`.

pub fn path() -> PathBuf {

    if let Some(p) = std::env::var_os("SPECTRA_SERVER").filter(|p| !p.is_empty()) {

        return PathBuf::from(p);

    }

    config_dir().join("client.toml")

}

fn config_dir() -> PathBuf {

    let base = std::env::var_os("XDG_CONFIG_HOME")

        .filter(|p| !p.is_empty())

        .map(PathBuf::from)

        .or_else(|| std::env::var_os("HOME").map(|h| PathBuf::from(h).join(".config")))

        .unwrap_or_else(|| PathBuf::from("."));

    base.join("spectra")

}

/// The client configuration, if this machine uses a Spectra elsewhere.

pub fn load() -> Result<Option<ClientCfg>> {

    let p = path();

    let text = match std::fs::read_to_string(&p) {

        Ok(t) => t,

        Err(e) if e.kind() == std::io::ErrorKind::NotFound => return Ok(None),

        Err(e) => return Err(e).with_context(|| format!("reading {}", p.display())),

    };

    let t: toml::Table = text.parse().with_context(|| format!("reading {}", p.display()))?;

    let get = |k: &str| t.get(k).and_then(|v| v.as_str()).map(String::from).with_context(|| format!("{} has no {k}", p.display()));

    let spki = hex::decode(get("tls_spki")?).ok().and_then(|b| b.try_into().ok()).with_context(|| format!("{}: tls_spki", p.display()))?;

    Ok(Some(ClientCfg { server: get("server")?, instance: get("instance")?, tls_spki: spki }))

}

fn save(cfg: &ClientCfg) -> Result<PathBuf> {

    let p = path();

    if let Some(dir) = p.parent() {

        std::fs::create_dir_all(dir)?;

    }

    std::fs::write(

        &p,

        format!(

            "# Spectra on another machine (spec §8.6), written by `spectra connect`.\n\nserver = \"{}\"\ninstance = \"{}\"                    # the instance key, delegated by the owner\ntls_spki = \"{}\"   # the certificate the instance key vouches for\n",

            cfg.server,

            cfg.instance,

            hex::encode(cfg.tls_spki)

        ),

    )?;

    Ok(p)

}

/// The key pair of the identity `key` in the owner's home, if it is theirs.

fn own(home: &Path, key: &str) -> Option<KeyPair> {

    let keys = home.join("keys");

    KeyPair::load(&keys.join(format!("{key}.secret")), &keys.join(format!("{key}.identity"))).ok()

}

pub async fn connect(_ctx: &Ctx, url: &str, owner_home: Option<PathBuf>) -> Result<i32> {

    let server = format!("https://{}", host_port(url)?);

    let home = owner_home.unwrap_or_else(oxy_core::repo::default_home);

    let owner = KeyPair::load_home(&home)

        .with_context(|| format!("the owner connects with their own identity: none usable in {} (or --owner-home)", home.display()))?;

    // Who is there, before trusting anything.

    let probe = Pinned::new(None);

    let anon = Client::at(Endpoint::Tls { addr: host_port(url)?, config: probe.client_config()? }, None);

    let r = anon.send("GET", "/api/v1/instance", &[], vec![]).await.with_context(|| format!("reaching {server}"))?;

    if r.status != 200 {

        bail!("{server} answered {} to /api/v1/instance: is it a Spectra?", r.status);

    }

    let answer = r.json()?;

    let (_, seen) = probe.seen().context("the server showed no certificate")?;

    let checked = spectra_mcp::instance::check(&answer, &seen)?;

    let instance_key = checked.instance.hash();

    // Whose it is, or whose it is waiting for.

    let recorded = checked.owner.clone();

    let named = answer.get("named_owner").and_then(Json::as_str).map(String::from);

    match (&recorded, &named) {

        (Some(k), _) if *k != owner.key.to_hex() && own(&home, k).is_none() => {

            bail!("{server} belongs to someone else (owner {})", &k[..12.min(k.len())]);

        }

        (None, Some(k)) if own(&home, k).is_none() => {

            bail!("{server} was set up for {}, which is not an identity in {}", &k[..12.min(k.len())], home.display());

        }

        (None, None) => bail!("{server} has no owner and names none"),

        _ => {}

    }

    // Trust: the owner's own identity delegates to that instance key now.

    if !owner.identity.delegates_to(&instance_key, DELEGATION_SCOPE, spectra_core::ids::now_ms()) {

        let dir = config_dir();

        std::fs::create_dir_all(&dir)?;

        let file = dir.join(format!("{}-instance.identity", safe(&checked.name)));

        std::fs::write(&file, checked.instance.encode())?;

        println!("{} {} {}", ui::caution(), ui::subject(&server), ui::dim("is not yet yours to trust"));

        println!("{}", ui::kv("instance", format!("{}{}{}", checked.name, ui::sep(), ui::hash(instance_key.short(12)))));

        println!("  {} {}", ui::note(), ui::dim("your identity does not delegate to its instance key; if this is your server, run:"));

        println!("    {}", ui::id(format!("oxy identity delegate add {} --scope changes", file.display())));

        println!("  {} {}", ui::note(), ui::dim("then run spectra connect again"));

        return Ok(1);

    }

    let cfg = ClientCfg { server: server.clone(), instance: instance_key.to_hex(), tls_spki: seen };

    let saved = save(&cfg)?;

    let pinned = cfg.endpoint()?;

    // Claim it, or bring it up to the owner's current identity.

    let mut claimed = false;

    match (&recorded, &named) {

        (None, Some(k)) => {

            let named_pair = own(&home, k).expect("checked above");

            let mut events =

                vec![WireEvent::from_new(&signed_event(&named_pair, "human", "identity.owner", identity_payload(&named_pair.identity)))];

            if let Some(e) = identity::rotation(&named_pair.identity, &home)? {

                events.push(WireEvent::from_new(&e));

            }

            let r = Client::at(pinned.clone(), None).send("POST", "/api/v1/claim", &[], serde_json::to_vec(&events)?).await?;

            if r.status != 200 {

                bail!("{server} refused the claim: {}", problem(&r.body));

            }

            claimed = true;

        }

        (Some(k), _) if *k != owner.key.to_hex() => {

            let rec_pair = own(&home, k).expect("checked above");

            let rec_id: Identity = rec_pair.identity.clone();

            if let Some(e) = identity::rotation(&rec_id, &home)? {

                let body = serde_json::to_vec(&vec![WireEvent::from_new(&e)])?;

                let r = Client::at(pinned.clone(), Some(rec_pair)).send("POST", "/api/v1/ledger/events", &[], body).await?;

                if r.status != 200 {

                    bail!("{server} refused the owner's current identity: {}", problem(&r.body));

                }

            }

        }

        _ => {}

    }

    println!("{} {}  {}", ui::done(if claimed { "Claimed" } else { "Connected" }), ui::subject(&checked.name), ui::path(&server));

    println!("{}", ui::kv("owner", format!("{}{}{}", ui::author(&owner.identity.name), ui::sep(), ui::hash(owner.key.short(12)))));

    println!("{}", ui::kv("instance", format!("{}{}", ui::hash(instance_key.short(12)), ui::dim(" (delegated by you)"))));

    println!(

        "{}",

        ui::kv("certificate", format!("{}{}", ui::hash(hex::encode(&seen[..8])), ui::dim(" (pinned; vouched for by the instance key)")))

    );

    println!("{}", ui::kv("config", ui::path(saved.display())));

    Ok(0)

}

fn safe(name: &str) -> String {

    let s: String = name.chars().map(|c| if c.is_ascii_alphanumeric() || c == '-' { c } else { '_' }).collect();

    if s.is_empty() {

        "spectra".into()

    } else {

        s

    }

}

fn problem(body: &[u8]) -> String {

    serde_json::from_slice::<Json>(body)

        .ok()

        .and_then(|v| v.get("detail").or_else(|| v.get("title")).and_then(Json::as_str).map(String::from))

        .unwrap_or_else(|| String::from_utf8_lossy(body).into_owned())

}