//! `install --game rust` and `update --game rust` — one pipeline, as for ServUO.
//!
//! docs/modules/rust/PLAN.md §34.2.3. What an instance is: one Rust server root, its plugin, and a
//! sidecar of its own — service, config, database, game port and web port — named by `--server-id`
//! (D148). What instances share: the one sidecar binary and the one bundle, so `update` moves every
//! instance on the host together (§34.4).
//!
//! The order follows ServUO's, for the same reasons:
//!
//! 1. **Resolve everything that can fail cheaply first** — the bundle, this host's binary, the
//!    server root and its framework, the plugin's config and the ports — so a run that cannot
//!    finish ends before anything is written.
//! 2. **The sidecar before the plugin.** Both frameworks load a plugin file the moment it lands,
//!    even on a running server (§34.2.3), so the sidecar it dials is registered first.
//! 3. **Provision the config before registering the service**, record last, handoff after that.

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

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

use super::npc;
use super::plugin::{self, ConfigView};
use super::record::{ComponentRecord, DeployedFile, Instance, NpcRecord, RustRecord, SCHEMA};
use super::server::{self, RustServer};
use super::sidecar;
use crate::bundle::{self, RustBundle};
use crate::cli::Cli;
use crate::install::Mode;
use crate::record::{now_rfc3339, BinaryRef, BundleRef, InstallerInfo, ServiceRecord};
use crate::sidecar::BinaryAction;
use crate::util::{write_atomic, TempDir};
use crate::{paths, service, ui};

/// The plugin's own default game port, and where the search for a free one starts.
const GAME_PORT_START: u16 = 7799;
/// Where the search for a free web port starts. Clear of ServUO's uo-link default (8080).
const WEB_PORT_START: u16 = 8090;

/// One instance this run is about, with every decision made and nothing written.
struct Planned {
    id: String,
    server: RustServer,
    running: bool,
    plugin_config: Option<ConfigView>,
    plugin_action: BinaryAction,
    /// Each helper in the release and what happens to it, in the release's (name) order.
    helper_actions: Vec<BinaryAction>,
    /// Helpers this instance's record holds that the release no longer ships: removed.
    retired_helpers: Vec<String>,
    /// RunicNPC, when the bundle carries it (D224): absent, identical or replaced.
    npc_action: Option<BinaryAction>,
    game_port: u16,
    web_port: u16,
    config_path: PathBuf,
    db_path: PathBuf,
    config_exists: bool,
}

pub fn deploy(cli: &Cli, mode: Mode) -> Result<()> {
    let layout = paths::layout();
    let record_path = layout.rust_record();
    let prior = RustRecord::load(&record_path)?;

    // ── Which instances ──────────────────────────────────────────────────────
    let targets: Vec<(String, PathBuf)> = match mode {
        Mode::Install => {
            let id = cli.server_id.clone().ok_or_else(|| {
                anyhow::anyhow!(
                    "install --game rust needs --server-id <id>: the id the website will know this \
                     server by, which also names its sidecar. For example:\n  \
                     runicgateway-installer install --game rust --rust /srv/rust --server-id main"
                )
            })?;
            let recorded = prior
                .as_ref()
                .and_then(|p| p.instances.get(&id))
                .map(|i| PathBuf::from(&i.server_root));
            let root = match (&cli.rust, recorded) {
                (Some(path), _) => PathBuf::from(path),
                (None, Some(root)) => root,
                (None, None) => bail!(
                    "install --game rust needs --rust <path>: the Rust server root, the directory \
                     holding RustDedicated"
                ),
            };
            vec![(id, root)]
        }
        Mode::Update => {
            if cli.server_id.is_some() || cli.rust.is_some() {
                bail!(
                    "update --game rust moves every Rust instance on this host together — they \
                     share one sidecar binary, and a host whose instances spoke two protocols is one \
                     no bundle describes. Run it without --server-id or --rust."
                );
            }
            let Some(prior) = prior.as_ref() else {
                bail!(
                    "nothing to update — no Rust deployment is recorded on this host (looked for {}). \
                     Run `install --game rust` first.",
                    record_path.display()
                );
            };
            prior
                .instances
                .iter()
                .map(|(id, i)| (id.clone(), PathBuf::from(&i.server_root)))
                .collect()
        }
    };

    // ── What to install ──────────────────────────────────────────────────────
    let (bundle, bundle_url) = bundle::fetch_rust(cli.bundle.as_deref())?;
    let asset = bundle.sidecar_asset()?.clone();
    println!(
        "\nRunic Gateway installer {} — Rust {} to bundle {} (protocol {}){}",
        env!("CARGO_PKG_VERSION"),
        if mode.is_update() {
            "update"
        } else {
            "install"
        },
        bundle.bundle,
        bundle.protocol,
        if cli.verify {
            "  [--verify: nothing will be written]"
        } else {
            ""
        }
    );
    println!();
    ui::row(
        "Sidecar",
        &format!(
            "{:<24} protocol {}",
            format!("rust-link {}", bundle.sidecar.tag),
            bundle.sidecar.protocol
        ),
    );
    ui::row(
        "Plugin",
        &format!(
            "{:<24} protocol {}",
            format!("Rust-Plugins {}", bundle.payload.tag),
            bundle.payload.protocol
        ),
    );
    if let Some(npc) = &bundle.npc {
        ui::row(
            "RunicNPC",
            &format!(
                "{:<24} API {}",
                format!("runicnpc-rust {}", npc.tag),
                npc.api
            ),
        );
    }

    // The plugin is fetched before anything is planned: its manifest is the last statement of the
    // protocol to check, and a pair that disagrees must stop the run before any file moves.
    let scratch = TempDir::new("runicgateway-rust")?;
    let tarball = scratch.path().join(&bundle.payload.asset.name);
    crate::net::download_verified(
        &bundle.payload.asset.url,
        &tarball,
        &bundle.payload.asset.sha256,
    )?;
    let released = plugin::read_tarball(&tarball)?;
    if released.manifest.version != bundle.payload.version {
        ui::warn(&format!(
            "the plugin tarball says version {} but bundle {} names {}. The checksum matched, so \
             this is a labelling mismatch in the release rather than a wrong download.",
            released.manifest.version, bundle.bundle, bundle.payload.version
        ));
    }
    if released.manifest.protocol != bundle.protocol {
        bail!(
            "the plugin in bundle {} declares protocol {}, and the bundle {}. The Rust game link \
             has no version handshake, so a mismatched plugin mis-parses rather than being \
             refused — refusing the pair here.",
            bundle.bundle,
            released.manifest.protocol,
            bundle.protocol
        );
    }

    // RunicNPC (D224), fetched and checked beside the plugin, before anything is planned. It is
    // required since RunicNPC's stage 9 (D310): the bridge refuses every NPC an event places
    // without it, so a bundle that cannot place it is refused before anything is written.
    let npc_released = match &bundle.npc {
        Some(component) => {
            let path = scratch.path().join(&component.asset.name);
            crate::net::download_verified(&component.asset.url, &path, &component.asset.sha256)?;
            let released = npc::read_tarball(&path)?;
            if released.manifest.api != component.api {
                bail!(
                    "RunicNPC in bundle {} answers API {}, but the bundle says {} — refusing a \
                     component the bundle does not describe.",
                    bundle.bundle,
                    released.manifest.api,
                    component.api
                );
            }
            if released.manifest.version != component.version {
                ui::warn(&format!(
                    "the RunicNPC tarball says version {} but bundle {} names {}. The checksum matched, \n                     so this is a labelling mismatch in the release rather than a wrong download.",
                    released.manifest.version, bundle.bundle, component.version
                ));
            }
            Some(released)
        }
        None => bail!(
            "bundle {} carries no RunicNPC, and Runic Gateway's Rust events need it: without it \
             the bridge refuses every NPC an event places. Install the current bundle (leave \
             --bundle off), or pin one published with RunicNPC v1.0.0 or later.",
            bundle.bundle
        ),
    };

    // ── Plan every instance ──────────────────────────────────────────────────
    let mut planned = Vec::new();
    for (id, root) in &targets {
        planned.push(plan_instance(
            cli,
            &layout,
            prior.as_ref(),
            id,
            root,
            &released,
            npc_released.as_ref(),
        )?);
    }
    let binary_action = crate::sidecar::decide(&asset, &layout.rust_sidecar_bin)?;
    print_plan(&layout, &planned, binary_action, &bundle, &released);

    if cli.verify {
        println!(
            "\nNothing was written. Re-run without --verify to {}.",
            if mode.is_update() { "update" } else { "deploy" }
        );
        return Ok(());
    }

    preflight_writable(&layout)?;

    // ── The sidecar binary, shared by every instance ─────────────────────────
    let prepared = service::prepare(layout.relocated);
    let binary_sha256 = if binary_action.writes() {
        // Every instance runs this one file: on Windows it is locked while any of them runs, and on
        // Linux replacing it leaves each one serving old code until restarted.
        let mut running: Vec<String> = prior
            .as_ref()
            .map(|p| p.instances.keys().cloned().collect())
            .unwrap_or_default();
        running.extend(planned.iter().map(|p| p.id.clone()));
        running.sort();
        running.dedup();
        service::stop_rust_instances(&prepared.manager, &running)?;
        let sha = crate::sidecar::place(&asset, &layout.rust_sidecar_bin, scratch.path())?;
        ui::ok(&format!(
            "rust-link binary verified    sha256 {}…",
            &asset.sha256[..8.min(asset.sha256.len())]
        ));
        sha
    } else {
        asset.sha256.trim().to_ascii_lowercase()
    };

    // ── Each instance ────────────────────────────────────────────────────────
    let mut record = prior
        .clone()
        .unwrap_or_else(|| empty_record(&bundle, &bundle_url));
    let mut handoffs = Vec::new();
    for plan in &planned {
        let (instance, doc, registered) = deploy_instance(
            &layout,
            &prepared,
            &bundle,
            &released,
            npc_released.as_ref(),
            plan,
            binary_action.writes(),
            prior
                .as_ref()
                .and_then(|p| p.instances.get(&plan.id))
                .map(|i| i.plugin_config_written)
                .unwrap_or(false),
        )?;
        record.instances.insert(plan.id.clone(), instance);
        handoffs.push((plan.id.clone(), doc, registered, plan.running));
    }

    // Instances this run did not touch still run the binary it just replaced.
    if binary_action.writes() {
        if let Some(prior) = &prior {
            for (id, instance) in &prior.instances {
                if planned.iter().any(|p| &p.id == id) || instance.service.is_none() {
                    continue;
                }
                match service::restart_rust_instance(id) {
                    Ok(()) => ui::ok(&format!(
                        "restarted {} on the new binary",
                        service::rust_service_name(id)
                    )),
                    Err(e) => ui::warn(&format!("could not restart {id} on the new binary: {e}")),
                }
            }
        }
    }

    // ── Record ───────────────────────────────────────────────────────────────
    record.schema = SCHEMA;
    record.installer = InstallerInfo {
        version: env!("CARGO_PKG_VERSION").to_string(),
    };
    record.updated = now_rfc3339();
    record.bundle = BundleRef {
        tag: bundle.bundle.clone(),
        protocol: bundle.protocol,
        url: bundle_url.clone(),
    };
    record.sidecar = component(
        &bundle.sidecar.repo,
        &bundle.sidecar.tag,
        &bundle.sidecar.version,
        "",
        bundle.sidecar.protocol,
    );
    record.binary = BinaryRef {
        path: layout.rust_sidecar_bin.display().to_string(),
        sha256: binary_sha256,
    };
    record.plugin = component(
        &bundle.payload.repo,
        &bundle.payload.tag,
        &bundle.payload.version,
        &bundle.payload.commit,
        bundle.payload.protocol,
    );
    // A bundle without RunicNPC leaves a recorded one where it is: it may be an operator's.
    if let Some(component) = &bundle.npc {
        record.npc = Some(NpcRecord {
            repo: component.repo.clone(),
            tag: component.tag.clone(),
            version: component.version.clone(),
            commit: component.commit.clone(),
            api: component.api,
        });
    }
    record.service_user_created |= prepared.user_created;

    match prior.as_ref() {
        Some(previous) if previous.same_deployment_as(&record) => {
            println!("\n  {} unchanged", record_path.display());
        }
        _ => {
            record.save(&record_path).with_context(|| {
                format!(
                    "cannot write {} — run as root/Administrator, or set {} for a test run",
                    record_path.display(),
                    paths::STATE_DIR_ENV
                )
            })?;
            println!("\n  Recorded {}", record_path.display());
        }
    }

    // ── What is left for the operator ────────────────────────────────────────
    match mode {
        Mode::Install => {
            let host = crate::install::resolve_host(cli);
            for (id, doc, registered, running) in &handoffs {
                println!(
                    "{}",
                    sidecar::handoff(
                        id,
                        doc,
                        &host,
                        cli.site_url.as_deref(),
                        *registered,
                        *running
                    )
                );
            }
        }
        Mode::Update => {
            let before = prior.as_ref().map(|p| p.bundle.clone());
            match before {
                Some(b) if b.tag == bundle.bundle => {
                    // The same bundle can still have written something: a plugin edited by hand is
                    // put back, which is what `doctor` tells an operator to run `update` for.
                    let restored = planned
                        .iter()
                        .filter(|p| {
                            p.plugin_action.writes()
                                || p.npc_action.is_some_and(|a| a.writes())
                                || p.helper_actions.iter().any(|a| a.writes())
                                || !p.retired_helpers.is_empty()
                        })
                        .count();
                    if restored == 0 && !binary_action.writes() {
                        println!("\nAlready on bundle {} — nothing moved.", bundle.bundle)
                    } else {
                        println!(
                            "\nAlready on bundle {} — put back what no longer matched it (see above).",
                            bundle.bundle
                        )
                    }
                }
                Some(b) => {
                    println!(
                        "\nMoved {} instance(s) from bundle {} to {}.",
                        planned.len(),
                        b.tag,
                        bundle.bundle
                    );
                    if b.protocol != bundle.protocol {
                        ui::warn(&format!(
                            "The protocol moved from {} to {}. The website's Rust module must speak \
                             {} too, or it will be refused with 409 — update the site first.",
                            b.protocol, bundle.protocol, bundle.protocol
                        ));
                    }
                }
                None => {}
            }
        }
    }
    Ok(())
}

/// Every decision for one instance, made without writing anything.
fn plan_instance(
    cli: &Cli,
    layout: &paths::Layout,
    prior: Option<&RustRecord>,
    id: &str,
    root: &Path,
    released: &plugin::Released,
    npc_released: Option<&npc::Released>,
) -> Result<Planned> {
    let server = server::open(root)
        .with_context(|| format!("cannot use {} as a Rust server root", root.display()))?;
    let recorded = prior.and_then(|p| p.instances.get(id));

    if let Some(instance) = recorded {
        if Path::new(&instance.server_root) != server.path {
            bail!(
                "instance {id:?} is recorded for {}, not {}. An id names one server; uninstall it \
                 first (`uninstall --game rust --server-id {id}`) to move it.",
                instance.server_root,
                server.path.display()
            );
        }
    }
    if let Some((other, _)) = prior.and_then(|p| {
        p.instances
            .iter()
            .find(|(other, i)| other.as_str() != id && Path::new(&i.server_root) == server.path)
    }) {
        bail!(
            "{} is already installed as instance {other:?}. One server root has one plugin and one \
             ServerId; run with --server-id {other}.",
            server.path.display()
        );
    }

    let plugin_config = plugin::read_config(&server.plugin_config_path())?;
    let held_game = prior.map(|p| p.game_ports_except(id)).unwrap_or_default();
    let game_port = match &plugin_config {
        Some(view) => {
            plugin::check_server_id(view, id, &server.plugin_config_path())?;
            // A config without a Port gets the plugin's default.
            let port = view.port.unwrap_or(GAME_PORT_START);
            if held_game.contains(&port) {
                bail!(
                    "{} says the plugin dials port {port}, which another Rust instance on this host \
                     already listens on. Give it a free Port and run again.",
                    server.plugin_config_path().display()
                );
            }
            port
        }
        None => sidecar::choose_port(GAME_PORT_START, &held_game, recorded.map(|i| i.game_port))?,
    };

    let held_web = prior.map(|p| p.web_ports_except(id)).unwrap_or_default();
    if let Some(port) = cli.web_port {
        if held_web.contains(&port) {
            bail!("--web-port {port} is already another Rust instance's web port");
        }
    }
    let web_port = match (cli.web_port, recorded) {
        (Some(port), _) => port,
        (None, Some(instance)) => instance.web_port,
        (None, None) => sidecar::choose_port(WEB_PORT_START, &held_web, None)?,
    };

    let plugin_action = match std::fs::read(server.plugin_path()) {
        Err(_) => BinaryAction::Install,
        Ok(bytes) if crate::util::sha256_bytes(&bytes) == released.sha256 => {
            BinaryAction::Unchanged
        }
        Ok(_) => BinaryAction::Replace,
    };
    // Helpers are decided the same way as the plugin: absent, identical or replaced. One the
    // operator deleted is put back — the installer owns it, and `doctor` says what its absence costs.
    let helper_actions = released
        .helpers
        .iter()
        .map(
            |helper| match std::fs::read(server.plugins_dir().join(&helper.name)) {
                Err(_) => BinaryAction::Install,
                Ok(bytes) if crate::util::sha256_bytes(&bytes) == helper.sha256 => {
                    BinaryAction::Unchanged
                }
                Ok(_) => BinaryAction::Replace,
            },
        )
        .collect();
    let retired_helpers = recorded
        .map(|i| {
            i.helpers
                .keys()
                .filter(|name| !released.helpers.iter().any(|h| &h.name == *name))
                .cloned()
                .collect()
        })
        .unwrap_or_default();
    // RunicNPC as the plugin is: put back when it was deleted or edited (D224).
    let npc_action =
        npc_released.map(
            |r| match std::fs::read(server.plugins_dir().join(npc::FILE)) {
                Err(_) => BinaryAction::Install,
                Ok(bytes) if crate::util::sha256_bytes(&bytes) == r.sha256 => {
                    BinaryAction::Unchanged
                }
                Ok(_) => BinaryAction::Replace,
            },
        );
    let config_path = layout.rust_config(id);
    Ok(Planned {
        id: id.to_string(),
        running: server::is_running(&server.path),
        config_exists: config_path.exists(),
        config_path,
        db_path: layout.rust_db(id),
        server,
        plugin_config,
        plugin_action,
        helper_actions,
        retired_helpers,
        npc_action,
        game_port,
        web_port,
    })
}

fn print_plan(
    layout: &paths::Layout,
    planned: &[Planned],
    binary: BinaryAction,
    bundle: &RustBundle,
    released: &plugin::Released,
) {
    ui::row(
        "binary",
        &format!("{}   {}", layout.rust_sidecar_bin.display(), binary.label()),
    );
    for p in planned {
        ui::heading(&format!("Instance {}", p.id));
        ui::row(
            "server",
            &format!(
                "{}  ({}, {})",
                p.server.path.display(),
                p.server.framework.as_str(),
                if p.running {
                    "running — the plugin loads at once"
                } else {
                    "not running — the plugin loads at next boot"
                }
            ),
        );
        ui::row(
            "plugin",
            &format!(
                "{}   {}",
                p.server.plugin_path().display(),
                p.plugin_action.label()
            ),
        );
        for (helper, action) in released.helpers.iter().zip(&p.helper_actions) {
            ui::row(
                "helper",
                &format!(
                    "{}   {}",
                    p.server.plugins_dir().join(&helper.name).display(),
                    action.label()
                ),
            );
        }
        for name in &p.retired_helpers {
            ui::row(
                "helper",
                &format!(
                    "{}   removed (no longer released)",
                    p.server.plugins_dir().join(name).display()
                ),
            );
        }
        if let Some(action) = p.npc_action {
            ui::row(
                "RunicNPC",
                &format!(
                    "{}   {}",
                    p.server.plugins_dir().join(npc::FILE).display(),
                    action.label()
                ),
            );
        }
        ui::row(
            "plugin config",
            &match &p.plugin_config {
                Some(_) => format!(
                    "{}   kept (the website's)",
                    p.server.plugin_config_path().display()
                ),
                None => format!(
                    "{}   written: ServerId {}, Port {}",
                    p.server.plugin_config_path().display(),
                    p.id,
                    p.game_port
                ),
            },
        );
        ui::row(
            "sidecar config",
            &format!(
                "{}   {}",
                p.config_path.display(),
                if p.config_exists { "kept" } else { "written" }
            ),
        );
        ui::row(
            "ports",
            &format!(
                "game 127.0.0.1:{}   web 127.0.0.1:{}",
                p.game_port, p.web_port
            ),
        );
        // RunicNPC's own requirements join the bridge's: it will not load without Kits (D217).
        let mut required = bundle.payload.compat.requires_plugins.clone();
        if let Some(component) = &bundle.npc {
            for name in &component.compat.requires_plugins {
                if !required.contains(name) {
                    required.push(name.clone());
                }
            }
        }
        let missing = plugin::missing_plugins(&p.server.plugins_dir(), &required);
        if !missing.is_empty() {
            ui::warn(&format!(
                "{} not in {} — the features that use {} stay off until you install {} from uMod. \
                 The installer does not fetch third-party plugins (D153).",
                missing.join(", "),
                p.server.plugins_dir().display(),
                if missing.len() == 1 { "it" } else { "them" },
                if missing.len() == 1 { "it" } else { "them" },
            ));
        }
    }
}

/// Writes one instance: plugin config, sidecar config, service, plugin — in that order.
#[allow(clippy::too_many_arguments)]
fn deploy_instance(
    layout: &paths::Layout,
    prepared: &service::Prepared,
    bundle: &RustBundle,
    released: &plugin::Released,
    npc_released: Option<&npc::Released>,
    plan: &Planned,
    binary_changed: bool,
    plugin_config_written_before: bool,
) -> Result<(Instance, sidecar::ConfigDoc, bool)> {
    ui::heading(&format!("Instance {}", plan.id));
    let data_dir = layout.rust_data_dir(&plan.id);
    std::fs::create_dir_all(&data_dir)
        .with_context(|| format!("cannot create {}", data_dir.display()))?;

    // The plugin's config, once, and only if it does not exist (§34.2.3).
    let plugin_config_path = plan.server.plugin_config_path();
    let wrote_plugin_config = plan.plugin_config.is_none();
    if wrote_plugin_config {
        if let Some(parent) = plugin_config_path.parent() {
            std::fs::create_dir_all(parent)
                .with_context(|| format!("cannot create {}", parent.display()))?;
        }
        write_atomic(
            &plugin_config_path,
            plugin::initial_config(&plan.id, plan.game_port).as_bytes(),
        )?;
        ui::ok(&format!("wrote {}", plugin_config_path.display()));
    }

    // The sidecar's config, once; the token is the sidecar's to generate.
    if !plan.config_exists {
        if let Some(parent) = plan.config_path.parent() {
            std::fs::create_dir_all(parent)
                .with_context(|| format!("cannot create {}", parent.display()))?;
        }
        write_atomic(
            &plan.config_path,
            sidecar::instance_config(&plan.id, plan.game_port, plan.web_port, &plan.db_path)
                .as_bytes(),
        )?;
    }
    let doc = sidecar::print_config(&layout.rust_sidecar_bin, &plan.config_path)?;
    if doc.protocol != bundle.protocol {
        bail!(
            "the installed rust-link sidecar reports protocol {} but bundle {} was composed at {}. \
             Refusing to register a service for a pair that was never checked together.",
            doc.protocol,
            bundle.bundle,
            bundle.protocol
        );
    }
    if doc.version != bundle.sidecar.version {
        ui::warn(&format!(
            "the installed binary reports version {} but bundle {} names {}. The checksum matched, \
             so this is a labelling mismatch in the release rather than a wrong download.",
            doc.version, bundle.bundle, bundle.sidecar.version
        ));
    }
    // The sidecar's server_id is a cross-check against the plugin's hello. An edited config that
    // names another server makes every hello log a disagreement, so it is said here, once.
    if !doc.game.server_id.is_empty() && doc.game.server_id != plan.id {
        ui::warn(&format!(
            "{} cross-checks server id {:?}, but this instance is {:?}; the sidecar will log a \
             disagreement on every connect.",
            doc.config_path, doc.game.server_id, plan.id
        ));
    }
    // An existing sidecar config is the operator's; what it says is what runs. Say so when it
    // disagrees with the plugin, because that pair never meets.
    if let Some(port) = sidecar::port_of(&doc.game.bind) {
        if port != plan.game_port {
            ui::warn(&format!(
                "{} listens for the plugin on {port}, but the plugin dials {}. Make them agree, or \
                 the plugin never connects.",
                doc.config_path, plan.game_port
            ));
        }
    }
    ui::row(
        "sidecar config",
        &format!(
            "{}   {}",
            doc.config_path,
            if doc.token_generated {
                "token generated"
            } else {
                "token kept"
            }
        ),
    );

    service::protect_config(
        &plan.config_path,
        &data_dir,
        prepared.user.as_deref(),
        layout.relocated,
    )?;
    let mut outcome = service::register_rust(
        prepared,
        layout,
        &plan.id,
        &plan.config_path,
        binary_changed,
    )?;
    service::grant_service_access(&plan.config_path, &data_dir, &outcome)?;
    service::start_registered(&mut outcome, &layout.rust_sidecar_bin, &plan.config_path)?;
    let service_record = match &outcome {
        service::Outcome::Registered {
            kind,
            name,
            user,
            state,
            ..
        } => {
            ui::row("service", &format!("{name}   {state}"));
            Some(ServiceRecord {
                kind: (*kind).to_string(),
                name: name.clone(),
                unit_path: None,
                user: user.clone(),
                // The account is shared with every instance and possibly with ServUO's sidecar, so
                // no single instance's removal may delete it (see `RustRecord`).
                user_created: false,
            })
        }
        service::Outcome::Skipped { reason, manual } => {
            ui::warn(&format!(
                "service NOT REGISTERED — {reason}.\n  The binary and config are in place; nothing is \
                 running them. Do this by hand:"
            ));
            print!("{manual}");
            None
        }
    };

    // The helpers before the plugin (D182): each loads the moment it lands, and the bridge reads a
    // helper's state at hello — a helper already there is one the bridge's first hello reports.
    // Written in place for the plugin's reason below.
    let mut helpers = std::collections::BTreeMap::new();
    for (helper, action) in released.helpers.iter().zip(&plan.helper_actions) {
        let path = plan.server.plugins_dir().join(&helper.name);
        if action.writes() {
            std::fs::create_dir_all(plan.server.plugins_dir()).with_context(|| {
                format!("cannot create {}", plan.server.plugins_dir().display())
            })?;
            std::fs::write(&path, &helper.source)
                .with_context(|| format!("cannot write {}", path.display()))?;
            ui::ok(&format!(
                "helper {}   {}",
                if *action == BinaryAction::Replace {
                    "replaced"
                } else {
                    "installed"
                },
                path.display()
            ));
        }
        helpers.insert(
            helper.name.clone(),
            DeployedFile {
                path: path.display().to_string(),
                sha256: helper.sha256.clone(),
            },
        );
    }
    for name in &plan.retired_helpers {
        let path = plan.server.plugins_dir().join(name);
        match std::fs::remove_file(&path) {
            Ok(()) => ui::ok(&format!("helper removed   {}", path.display())),
            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
            Err(e) => ui::warn(&format!("could not remove {}: {e}", path.display())),
        }
    }

    // RunicNPC before the bridge (D224): the bridge reports it at hello, and one already loaded is
    // one its first hello names. Written in place, for the plugin's reason below.
    let npc_file = match (npc_released, plan.npc_action) {
        (Some(r), Some(action)) => {
            let path = plan.server.plugins_dir().join(npc::FILE);
            if action.writes() {
                std::fs::create_dir_all(plan.server.plugins_dir()).with_context(|| {
                    format!("cannot create {}", plan.server.plugins_dir().display())
                })?;
                std::fs::write(&path, &r.source)
                    .with_context(|| format!("cannot write {}", path.display()))?;
                ui::ok(&format!(
                    "RunicNPC {}   {}",
                    if action == BinaryAction::Replace {
                        "replaced"
                    } else {
                        "installed"
                    },
                    path.display()
                ));
            }
            Some(DeployedFile {
                path: path.display().to_string(),
                sha256: r.sha256.clone(),
            })
        }
        _ => None,
    };

    // The plugin last: it loads the moment it lands, and its sidecar is now there to dial.
    let plugin_path = plan.server.plugin_path();
    if plan.plugin_action.writes() {
        std::fs::create_dir_all(plan.server.plugins_dir())
            .with_context(|| format!("cannot create {}", plan.server.plugins_dir().display()))?;
        // Overwritten in place, NOT `write_atomic`. Oxide and Carbon watch the plugins directory
        // and reload on a CHANGE; `write_atomic` removes the old file and renames a `.tmp` over it,
        // which both frameworks see as a delete — they unload the bridge — and a rename they
        // ignore, so the new file is never loaded. On a running server that was an `update` that
        // silently took the bridge down until the next boot (the phase 18 walk, on all three
        // instances and both frameworks). A write in place is what an operator's `cp` does, and
        // it reloads. A crash mid-write leaves a file that fails to compile; `doctor` reports it
        // as not the deployed file and `update` writes it again.
        std::fs::write(&plugin_path, &released.source)
            .with_context(|| format!("cannot write {}", plugin_path.display()))?;
        ui::ok(&format!(
            "plugin {}   {}",
            if plan.plugin_action == BinaryAction::Replace {
                "replaced"
            } else {
                "installed"
            },
            plugin_path.display()
        ));
    }

    Ok((
        Instance {
            server_root: plan.server.path.display().to_string(),
            framework: plan.server.framework.as_str().to_string(),
            plugin_path: plugin_path.display().to_string(),
            plugin_sha256: released.sha256.clone(),
            helpers,
            npc: npc_file,
            plugin_config: plugin_config_path.display().to_string(),
            plugin_config_written: wrote_plugin_config || plugin_config_written_before,
            game_port: plan.game_port,
            web_port: sidecar::port_of(&doc.web.bind).unwrap_or(plan.web_port),
            config_path: doc.config_path.clone(),
            db_path: doc.store.path.clone(),
            service: service_record,
        },
        doc,
        outcome.registered(),
    ))
}

fn component(repo: &str, tag: &str, version: &str, commit: &str, protocol: u32) -> ComponentRecord {
    ComponentRecord {
        repo: repo.to_string(),
        tag: tag.to_string(),
        version: version.to_string(),
        commit: commit.to_string(),
        protocol,
    }
}

fn empty_record(bundle: &RustBundle, url: &str) -> RustRecord {
    RustRecord {
        schema: SCHEMA,
        installer: InstallerInfo {
            version: env!("CARGO_PKG_VERSION").to_string(),
        },
        updated: String::new(),
        bundle: BundleRef {
            tag: bundle.bundle.clone(),
            protocol: bundle.protocol,
            url: url.to_string(),
        },
        sidecar: component("", "", "", "", 0),
        binary: BinaryRef {
            path: String::new(),
            sha256: String::new(),
        },
        plugin: component("", "", "", "", 0),
        npc: None,
        service_user_created: false,
        instances: Default::default(),
        extra: Default::default(),
    }
}

/// Fails before anything is written if this process cannot write where it must.
fn preflight_writable(layout: &paths::Layout) -> Result<()> {
    let bin_dir = layout
        .rust_sidecar_bin
        .parent()
        .unwrap_or(&layout.rust_sidecar_bin)
        .to_path_buf();
    for dir in [
        layout.rust_config_dir(),
        layout.data_dir.join("rust"),
        bin_dir,
    ] {
        std::fs::create_dir_all(&dir)
            .and_then(|_| {
                let probe = dir.join(".runicgateway-write-test");
                std::fs::write(&probe, b"")?;
                std::fs::remove_file(&probe)
            })
            .with_context(|| {
                format!(
                    "cannot write to {}. Run as {}, or set {} for a test run (no service is \
                     registered then).",
                    dir.display(),
                    if cfg!(windows) {
                        "Administrator"
                    } else {
                        "root (sudo)"
                    },
                    paths::STATE_DIR_ENV
                )
            })?;
    }
    Ok(())
}