//! Bootstrap host-side artifacts on every archipelago startup.
//!
//! The update pipeline swaps the archipelago binary but does not touch
//! scripts, systemd units, or nginx configuration — those are installed
//! once by the ISO builder. Without this module, changes to
//! `container-doctor.sh`, the doctor service/timer, or the nginx config
//! never reach boxes installed before the change.
//!
//! Two things are synced on startup:
//!   1. Doctor artifacts (container-doctor.sh + service + timer).
//!   2. An nginx `location /api/app-catalog` proxy block — required for
//!      the App Store catalog proxy to actually reach the backend.
//!
//! Idempotent: no-ops on boxes that are already in sync. All work is
//! best-effort — failures are logged but never abort the backend.

use anyhow::{Context, Result};
use std::path::Path;
use tokio::fs;
use tracing::{debug, info, warn};

use crate::update::host_sudo;

const DOCTOR_SH: &str = include_str!("../../../scripts/container-doctor.sh");
const DOCTOR_SERVICE: &str =
    include_str!("../../../image-recipe/configs/archipelago-doctor.service");
const DOCTOR_TIMER: &str =
    include_str!("../../../image-recipe/configs/archipelago-doctor.timer");

const DOCTOR_SH_PATH: &str = "/home/archipelago/archy/scripts/container-doctor.sh";
const DOCTOR_SERVICE_PATH: &str = "/etc/systemd/system/archipelago-doctor.service";
const DOCTOR_TIMER_PATH: &str = "/etc/systemd/system/archipelago-doctor.timer";

const NGINX_CONF_PATH: &str = "/etc/nginx/sites-available/archipelago";

/// Inserted into every server block of the nginx config that lacks the
/// `/api/app-catalog` proxy. Kept in sync with the canonical block in
/// image-recipe/configs/nginx-archipelago.conf.
const NGINX_APP_CATALOG_BLOCK: &str = "\n    # App Store catalog proxy — backend fetches from configured registries\n    # so the browser doesn't hit CORS/CSP. Without this block nginx falls\n    # through to the SPA index.html and the frontend gets HTML back instead\n    # of JSON.\n    location /api/app-catalog {\n        proxy_pass http://127.0.0.1:5678;\n        proxy_http_version 1.1;\n        proxy_set_header Host $host;\n        proxy_set_header X-Real-IP $remote_addr;\n        proxy_set_header Cookie $http_cookie;\n        proxy_connect_timeout 15s;\n        proxy_read_timeout 30s;\n        proxy_send_timeout 15s;\n        error_page 502 503 = @backend_unavailable;\n        error_page 504 = @backend_timeout;\n    }\n\n";

/// Entry point called from main startup. Never returns an error to the caller —
/// failing to bootstrap host artifacts must not prevent the backend from serving.
pub async fn ensure_doctor_installed() {
    match run().await {
        Ok(changed) if changed => info!("Doctor artifacts synchronized with binary"),
        Ok(_) => debug!("Doctor artifacts already in sync"),
        Err(e) => warn!("Doctor bootstrap failed (non-fatal): {:#}", e),
    }
    match run_nginx().await {
        Ok(true) => info!("Patched nginx config to proxy /api/app-catalog"),
        Ok(false) => debug!("Nginx already has /api/app-catalog block"),
        Err(e) => warn!("Nginx bootstrap failed (non-fatal): {:#}", e),
    }
}

async fn run() -> Result<bool> {
    // Dev-box guard: on contributors' laptops `/home/archipelago/archy` is
    // typically a symlink into the git checkout, and writing through it
    // would clobber the working tree with whatever the binary happens to
    // have been compiled from. Production ISO installs materialize a real
    // directory.
    let home_archy = Path::new("/home/archipelago/archy");
    if fs::symlink_metadata(home_archy)
        .await
        .map(|m| m.file_type().is_symlink())
        .unwrap_or(false)
    {
        debug!("/home/archipelago/archy is a symlink — skipping doctor bootstrap (dev box)");
        return Ok(false);
    }

    // Skip entirely on machines without the canonical scripts directory —
    // writing orphan files there just causes confusion.
    let scripts_dir = Path::new(DOCTOR_SH_PATH)
        .parent()
        .context("doctor script path has no parent")?;
    if !scripts_dir.exists() {
        debug!(
            "Scripts dir {} missing — skipping doctor bootstrap",
            scripts_dir.display()
        );
        return Ok(false);
    }

    let mut changed = false;

    // 1. Script — lives in archipelago's home dir, user-writable.
    if needs_write(DOCTOR_SH_PATH, DOCTOR_SH).await {
        fs::write(DOCTOR_SH_PATH, DOCTOR_SH)
            .await
            .with_context(|| format!("write {}", DOCTOR_SH_PATH))?;
        let _ = tokio::process::Command::new("chmod")
            .args(["+x", DOCTOR_SH_PATH])
            .status()
            .await;
        info!("Updated {}", DOCTOR_SH_PATH);
        changed = true;
    }

    // 2. Systemd unit files — /etc is restricted; route through host_sudo.
    let service_changed = write_root_if_needed(DOCTOR_SERVICE_PATH, DOCTOR_SERVICE).await?;
    let timer_changed = write_root_if_needed(DOCTOR_TIMER_PATH, DOCTOR_TIMER).await?;
    changed = changed || service_changed || timer_changed;

    // 3. Reload + enable. Only when we actually touched units, or when the
    // timer isn't enabled yet (catches fresh upgrades of boxes that predate
    // the doctor entirely).
    let timer_enabled = is_timer_enabled().await;
    if service_changed || timer_changed || !timer_enabled {
        if let Err(e) = host_sudo(&["systemctl", "daemon-reload"]).await {
            warn!("daemon-reload failed: {:#}", e);
        }
        if let Err(e) = host_sudo(&["systemctl", "enable", "--now", "archipelago-doctor.timer"])
            .await
        {
            warn!("enable archipelago-doctor.timer failed: {:#}", e);
        } else if !timer_enabled {
            info!("Enabled archipelago-doctor.timer");
        }
    }

    Ok(changed)
}

async fn needs_write(path: &str, expected: &str) -> bool {
    match fs::read_to_string(path).await {
        Ok(current) => current != expected,
        Err(_) => true,
    }
}

/// Write content to a root-owned path via `sudo mv` of a user-owned tmp file.
/// Returns true if a write happened.
async fn write_root_if_needed(path: &str, content: &str) -> Result<bool> {
    if !needs_write(path, content).await {
        return Ok(false);
    }
    let tmp = format!(
        "/tmp/archipelago-bootstrap-{}-{}.tmp",
        std::process::id(),
        Path::new(path)
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("unit")
    );
    fs::write(&tmp, content)
        .await
        .with_context(|| format!("write tmp {}", tmp))?;
    let status = host_sudo(&["mv", &tmp, path])
        .await
        .with_context(|| format!("sudo mv {} -> {}", tmp, path))?;
    if !status.success() {
        let _ = fs::remove_file(&tmp).await;
        anyhow::bail!("sudo mv to {} exited with {}", path, status);
    }
    info!("Updated {}", path);
    Ok(true)
}

async fn is_timer_enabled() -> bool {
    tokio::process::Command::new("systemctl")
        .args(["is-enabled", "--quiet", "archipelago-doctor.timer"])
        .status()
        .await
        .map(|s| s.success())
        .unwrap_or(false)
}

/// Patch the nginx site config to add a `/api/app-catalog` proxy block if
/// it's missing. The original ISO shipped individual per-endpoint `location`
/// blocks and no catch-all `/api/`, so `/api/app-catalog` silently fell
/// through to the SPA `index.html` and the frontend got HTML instead of
/// JSON. We anchor the insert to the DWN comment that already sits right
/// after the `/api/blob` block, so the new block lands in both the HTTP
/// and HTTPS server blocks.
///
/// Validates via `nginx -t` before reloading. On failure the patch is
/// rolled back from a backup written just before the write.
async fn run_nginx() -> Result<bool> {
    // Skip on dev symlinks — we don't want to touch `/etc/nginx` on laptops.
    let home_archy = Path::new("/home/archipelago/archy");
    if fs::symlink_metadata(home_archy)
        .await
        .map(|m| m.file_type().is_symlink())
        .unwrap_or(false)
    {
        return Ok(false);
    }

    if !Path::new(NGINX_CONF_PATH).exists() {
        debug!(
            "{} missing — skipping nginx bootstrap",
            NGINX_CONF_PATH
        );
        return Ok(false);
    }

    let content = fs::read_to_string(NGINX_CONF_PATH)
        .await
        .with_context(|| format!("read {}", NGINX_CONF_PATH))?;
    if content.contains("location /api/app-catalog") {
        return Ok(false);
    }

    // The DWN comment sits at the same indent right after the `/api/blob`
    // block in both server blocks — a stable anchor that existed on every
    // ISO shipped to date. If it's absent (config got heavily customized),
    // we bail rather than guess where to splice.
    let anchor = "    # DWN endpoints — peer access over Tor (no auth)";
    if !content.contains(anchor) {
        warn!("nginx conf missing DWN anchor — skipping /api/app-catalog patch");
        return Ok(false);
    }

    let replacement = format!("{}{}", NGINX_APP_CATALOG_BLOCK, anchor);
    let patched = content.replace(anchor, &replacement);

    // Write patched config via a user-owned tmp + sudo mv, after stashing
    // a backup so we can revert if `nginx -t` hates what we produced.
    let pid = std::process::id();
    let tmp = format!("/tmp/archipelago-nginx-{}.conf", pid);
    fs::write(&tmp, &patched)
        .await
        .with_context(|| format!("write {}", tmp))?;

    let backup = format!("/tmp/archipelago-nginx-backup-{}.conf", pid);
    if let Err(e) = host_sudo(&["cp", NGINX_CONF_PATH, &backup]).await {
        let _ = fs::remove_file(&tmp).await;
        return Err(e.context("backup nginx conf"));
    }

    let mv = host_sudo(&["mv", &tmp, NGINX_CONF_PATH]).await;
    match mv {
        Ok(s) if s.success() => {}
        Ok(s) => {
            let _ = fs::remove_file(&tmp).await;
            anyhow::bail!("sudo mv nginx conf exited with {}", s);
        }
        Err(e) => {
            let _ = fs::remove_file(&tmp).await;
            return Err(e.context("mv tmp -> nginx conf"));
        }
    }

    // Validate.
    let test = host_sudo(&["nginx", "-t"]).await;
    let valid = matches!(&test, Ok(s) if s.success());
    if !valid {
        warn!("nginx -t failed after patch — reverting");
        let _ = host_sudo(&["mv", &backup, NGINX_CONF_PATH]).await;
        if let Err(e) = test {
            return Err(e.context("nginx -t"));
        }
        anyhow::bail!("nginx config invalid after patch — reverted");
    }

    // Reload nginx so the new block takes effect immediately. Reload (not
    // restart) keeps in-flight connections alive.
    if let Err(e) = host_sudo(&["systemctl", "reload", "nginx"]).await {
        warn!("nginx reload failed (non-fatal): {:#}", e);
    }
    let _ = host_sudo(&["rm", "-f", &backup]).await;
    Ok(true)
}