impulse-server-kit 1.1.9

Highly configurable backend framework based on `salvo`
Documentation 
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//! Configuration for the SSR adapter.

use std::path::PathBuf;
use std::sync::Arc;

use serde::{Deserialize, Serialize};

/// Conventional sub-directory under `site_root` that holds the wasm/JS/CSS
/// bundle. Matches `cargo-leptos`'s default output layout.
pub const PKG_SUBDIR: &str = "pkg";

/// Default local dist directory; matches `impulse-static-server`'s convention.
pub const LOCAL_FRONTEND_DISTRIBUTABLE: &str = "dist";

/// Default container-deployment dist directory; matches `impulse-static-server`'s convention.
pub const CONTAINER_FRONTEND_DISTRIBUTABLE: &str = "/usr/local/frontend-dist";

/// Environment variable that overrides the dist path at runtime.
pub const FRONTEND_DIST_ENV: &str = "IMPULSE_FRONTEND_DIST";

/// SEO defaults consumed by the SSR HTML prefix builder.
///
/// These defaults are written into the rendered `<head>` only when the
/// rendered tree does not already supply a corresponding `leptos_meta`
/// element. The fields map to standard SEO/social metadata.
#[derive(Clone, Debug, Default, Serialize, Deserialize)]
pub struct SeoDefaults {
  /// Title template with `{}` substituted by the page-specific title.
  /// Example: `"{} | Impulse"`.
  #[serde(default)]
  pub title_template: Option<String>,
  /// Default `<title>` used when the rendered tree does not set one.
  #[serde(default)]
  pub default_title: Option<String>,
  /// Default `<meta name="description">` content.
  #[serde(default)]
  pub description: Option<String>,
  /// Default `og:image` URL.
  #[serde(default)]
  pub og_image: Option<String>,
  /// Brand logo URL emitted as `og:logo`. Not part of the original OG spec
  /// but consumed by some validators and structured-data scrapers; commonly
  /// distinct from `og_image` (square mark vs. social preview).
  #[serde(default)]
  pub og_logo: Option<String>,
  /// Canonical base URL; the request path is appended to form
  /// `<link rel="canonical">`.
  #[serde(default)]
  pub canonical_base: Option<String>,
  /// Default Twitter handle for `twitter:site`.
  #[serde(default)]
  pub twitter_handle: Option<String>,
  /// Default `robots` directive (e.g. `"index,follow"`).
  #[serde(default)]
  pub robots: Option<String>,
  /// Default `<html lang>` value (e.g. `"en"`).
  ///
  /// Also used to populate `og:locale` when set. For OpenGraph the value is
  /// normalised to a `lang_REGION` form (e.g. `en` → `en_US`, `ru` → `ru_RU`)
  /// per the OG spec.
  #[serde(default)]
  pub locale: Option<String>,
  /// Brand name emitted as `og:site_name`. Independent from `default_title`
  /// because most sites render `Brand` once and `Page Title — Brand` per page.
  /// Falls back to `default_title` when unset.
  #[serde(default)]
  pub site_name: Option<String>,
}

/// What to do when the SSR handler cannot produce a useful response.
#[derive(Clone, Default)]
pub enum FallbackStrategy {
  /// Render a minimal, JS-free 404/500 page from `impulse-error-pages`.
  #[default]
  ErrorPage,
  /// User-supplied fallback HTML.
  Custom(Arc<dyn Fn() -> String + Send + Sync>),
}

impl std::fmt::Debug for FallbackStrategy {
  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    match self {
      FallbackStrategy::ErrorPage => f.write_str("ErrorPage"),
      FallbackStrategy::Custom(_) => f.write_str("Custom(<fn>)"),
    }
  }
}

/// SSR adapter options.
///
/// Build via [`LeptosOptions::from_generic_values`] when the configuration
/// already lives in YAML, or construct manually for tests.
#[derive(Clone, Debug)]
pub struct LeptosOptions {
  /// Bundle name. Used to compute URLs for the wasm/JS/CSS bundle, e.g.
  /// `/pkg/<output_name>.js`.
  pub output_name: String,
  /// Path to the front-end distributable directory (the `dist/` folder built
  /// by `cargo-leptos` / `trunk`). All static files — wasm bundle, CSS,
  /// images, favicon, robots.txt — are served from this directory.
  ///
  /// Resolution order:
  /// 1. `IMPULSE_FRONTEND_DIST` environment variable, if set.
  /// 2. `frontend_dist_path` from config.
  /// 3. `./dist` if it exists.
  /// 4. `/usr/local/frontend-dist` (container default).
  pub site_root: PathBuf,
  /// URL prefix under which `#[server]` functions are mounted. Used by
  /// [`crate::leptos_ssr::server_fn_router`] when building the Salvo router.
  pub server_fn_prefix: String,
  /// SEO defaults injected into the rendered HTML prefix.
  pub seo_defaults: SeoDefaults,
  /// Fallback when rendering yields no content.
  pub fallback: FallbackStrategy,
  /// When `true`, the rendered HTML embeds the hydration bootstrap
  /// `<script>` and links the wasm bundle. Set to `true` when shipping a
  /// matching `hydrate`-mode wasm bundle.
  pub include_hydration_script: bool,
  /// Streaming mode used by the SSR handler.
  pub stream_mode: super::handler::SsrStreamMode,
}

impl Default for LeptosOptions {
  fn default() -> Self {
    Self {
      output_name: String::new(),
      site_root: PathBuf::from(LOCAL_FRONTEND_DISTRIBUTABLE),
      server_fn_prefix: "/api".to_string(),
      seo_defaults: SeoDefaults::default(),
      fallback: FallbackStrategy::ErrorPage,
      include_hydration_script: false,
      stream_mode: super::handler::SsrStreamMode::InOrder,
    }
  }
}

impl LeptosOptions {
  /// Resolve the front-end dist directory following the documented order:
  /// env var → config value → `./dist` → `/usr/local/frontend-dist`.
  pub fn resolve_site_root(g: &crate::setup::GenericValues) -> PathBuf {
    if let Ok(env_path) = std::env::var(FRONTEND_DIST_ENV)
      && !env_path.is_empty()
    {
      return PathBuf::from(env_path);
    }
    if let Some(p) = &g.frontend_dist_path {
      return p.clone();
    }
    let local = PathBuf::from(LOCAL_FRONTEND_DISTRIBUTABLE);
    if local.exists() {
      return local;
    }
    PathBuf::from(CONTAINER_FRONTEND_DISTRIBUTABLE)
  }

  /// Build options from the generic YAML configuration. Missing fields fall
  /// back to sensible defaults.
  pub fn from_generic_values(g: &crate::setup::GenericValues) -> Self {
    let mut opts = LeptosOptions {
      site_root: LeptosOptions::resolve_site_root(g),
      ..Default::default()
    };
    if let Some(name) = &g.leptos_output_name {
      opts.output_name = name.clone();
    } else {
      opts.output_name = g.app_name.clone();
    }
    if let Some(prefix) = &g.leptos_server_fn_prefix {
      opts.server_fn_prefix = prefix.clone();
    }
    if let Some(seo) = &g.leptos_seo {
      opts.seo_defaults = seo.clone();
    }
    opts
  }
}