euv_cli/build/

fn.rs

use super::*;

/// Checks whether `wasm_pack_args` already contains a build mode flag.
///
/// Returns `true` if any of `--dev`, `--release`, or `--profiling`
/// is present in the arguments list.
///
/// # Arguments
///
/// - `&[String]` - The wasm-pack arguments to search.
///
/// # Returns
///
/// - `bool` - Whether a build mode flag is already present.
pub fn has_build_mode_flag(wasm_pack_args: &[String]) -> bool {
    wasm_pack_args
        .iter()
        .any(|arg: &String| arg == DEV_FLAG || arg == RELEASE_FLAG || arg == PROFILING_FLAG)
}

/// Filters out euv-specific arguments from the wasm-pack arguments.
///
/// First locates the genuine passthrough arguments by taking everything
/// after the last `--` separator (or the full list if no `--` is present).
/// Then removes all known euv-specific flags and their values so that
/// only wasm-pack-compatible arguments remain.
///
/// # Arguments
///
/// - `&[String]` - The raw wasm-pack arguments to filter.
///
/// # Returns
///
/// - `Vec<String>` - The filtered arguments safe for wasm-pack.
pub fn filter_euv_args(wasm_pack_args: &[String]) -> Vec<String> {
    let raw_args: &[String] = if let Some(position) = wasm_pack_args
        .iter()
        .rposition(|arg: &String| arg == DOUBLE_DASH)
    {
        &wasm_pack_args[position + 1..]
    } else {
        wasm_pack_args
    };
    let mut filtered: Vec<String> = Vec::new();
    let mut skip_next: bool = false;
    for arg in raw_args {
        if skip_next {
            skip_next = false;
            continue;
        }
        // Compare the flag NAME, not the whole argument: clap accepts both
        // `--port 3000` and `--port=3000`, and only the first form ever
        // matched `EUV_ARGS` exactly. Without the split, `--port=3000` was
        // forwarded to wasm-pack even though `reconcile_args` had already
        // consumed its value — the same string both used and leaked.
        let name: &str = arg.split('=').next().unwrap_or(arg.as_str());
        if EUV_ARGS.contains(&name) {
            if arg.contains('=') || name == NO_GITIGNORE_ARG {
                // `--no-gitignore` is a bare boolean: there is no value to
                // skip, so treating it like `--port 3000` ate whatever
                // argument followed it.
                continue;
            }
            skip_next = true;
            continue;
        }
        filtered.push(arg.clone());
    }
    filtered
}

/// Reconciles euv-specific arguments that may have been collected into
/// `wasm_pack_args` (e.g. when placed after `--`) back into the
/// corresponding `ModeArgs` fields.
///
/// Because clap's `trailing_var_arg` collects all unrecognized arguments
/// into `wasm_pack_args`, any euv flag placed after `--` is not parsed
/// by clap into its dedicated field. This function scans `wasm_pack_args`
/// for known euv flags and overwrites the `ModeArgs` fields so that the
/// rest of the codebase can rely on the typed accessors regardless of
/// argument order.
///
/// # Arguments
///
/// - `&mut ModeArgs` - The CLI arguments to reconcile in-place.
pub fn reconcile_args(args: &mut ModeArgs) {
    let wasm_pack_args: Vec<String> = args.get_wasm_pack_args().clone();
    let mut crate_path: Option<PathBuf> = None;
    let mut port: Option<u16> = None;
    let mut www_dir: Option<String> = None;
    let mut index_html: Option<Option<PathBuf>> = None;
    let mut no_gitignore: Option<bool> = None;
    let mut dev: Option<bool> = None;
    let mut release: Option<bool> = None;
    let mut profiling: Option<bool> = None;
    let mut iter: Iter<String> = wasm_pack_args.iter();
    while let Some(arg) = iter.next() {
        match arg.as_str() {
            CRATE_PATH_ARG | CRATE_PATH_ARG_SHORT => {
                if let Some(value) = iter.next() {
                    crate_path = Some(PathBuf::from(value));
                }
            }
            PORT_ARG | PORT_ARG_SHORT => {
                if let Some(value) = iter.next()
                    && let Ok(parsed_port) = value.parse::<u16>()
                {
                    port = Some(parsed_port);
                }
            }
            WWW_DIR_ARG => {
                if let Some(value) = iter.next() {
                    www_dir = Some(value.clone());
                }
            }
            INDEX_HTML_ARG => {
                if let Some(value) = iter.next() {
                    index_html = Some(Some(PathBuf::from(value)));
                }
            }
            NO_GITIGNORE_ARG => {
                no_gitignore = Some(true);
            }
            DEV_FLAG => {
                dev = Some(true);
            }
            RELEASE_FLAG => {
                release = Some(true);
            }
            PROFILING_FLAG => {
                profiling = Some(true);
            }
            other => {
                if let Some(value) = other.strip_prefix(&format!("{CRATE_PATH_ARG}=")) {
                    crate_path = Some(PathBuf::from(value));
                } else if let Some(value) = other.strip_prefix(&format!("{PORT_ARG}=")) {
                    if let Ok(parsed_port) = value.parse::<u16>() {
                        port = Some(parsed_port);
                    }
                } else if let Some(value) = other.strip_prefix(&format!("{WWW_DIR_ARG}=")) {
                    www_dir = Some(value.to_string());
                } else if let Some(value) = other.strip_prefix(&format!("{INDEX_HTML_ARG}=")) {
                    index_html = Some(Some(PathBuf::from(value)));
                }
            }
        }
    }
    if let Some(value) = crate_path {
        args.set_crate_path(value);
    }
    if let Some(value) = port {
        args.set_port(value);
    }
    if let Some(value) = www_dir {
        args.set_www_dir(value);
    }
    if let Some(value) = index_html {
        args.set_index_html(value);
    }
    if let Some(value) = no_gitignore {
        args.set_no_gitignore(value);
    }
    if let Some(value) = dev {
        args.set_dev(value);
    }
    if let Some(value) = release {
        args.set_release(value);
    }
    if let Some(value) = profiling {
        args.set_profiling(value);
    }
}

/// Resolves the build mode from CLI arguments.
///
/// First checks the explicit `--dev`, `--release`, and `--profiling` flags on `ModeArgs`.
/// If none of those are set, inspects `wasm_pack_args` for any build mode flag
/// that may have been forwarded by the user.
/// Defaults to `BuildMode::Dev` if no build mode flag is found anywhere.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing the build mode flags and wasm_pack_args.
///
/// # Returns
///
/// - `BuildMode` - The resolved build mode.
pub fn resolve_build_mode(args: &ModeArgs) -> BuildMode {
    if args.get_profiling() {
        BuildMode::Profiling
    } else if args.get_release() {
        BuildMode::Release
    } else if args.get_dev() {
        BuildMode::Dev
    } else if args
        .get_wasm_pack_args()
        .iter()
        .any(|arg: &String| arg == PROFILING_FLAG)
    {
        BuildMode::Profiling
    } else if args
        .get_wasm_pack_args()
        .iter()
        .any(|arg: &String| arg == RELEASE_FLAG)
    {
        BuildMode::Release
    } else {
        BuildMode::Dev
    }
}

/// Converts a `BuildMode` to the corresponding wasm-pack flag string.
///
/// # Arguments
///
/// - `BuildMode` - The build mode to convert.
///
/// # Returns
///
/// - `&'static str` - The wasm-pack command-line flag.
pub fn build_mode_to_flag(build_mode: BuildMode) -> &'static str {
    match build_mode {
        BuildMode::Dev => DEV_FLAG,
        BuildMode::Release => RELEASE_FLAG,
        BuildMode::Profiling => PROFILING_FLAG,
    }
}

/// Builds a `Gitignore` matcher from the `.gitignore` file at the given root path.
///
/// # Arguments
///
/// - `&PathBuf` - The root directory where `.gitignore` is located.
///
/// # Returns
///
/// - `Gitignore` - The compiled gitignore matcher.
async fn build_gitignore(root: &PathBuf) -> Gitignore {
    let gitignore_path: PathBuf = root.join(GITIGNORE_FILE_NAME);
    let mut builder: GitignoreBuilder = GitignoreBuilder::new(root);
    let gitignore_exists: bool = metadata(&gitignore_path).await.is_ok();
    if gitignore_exists && let Some(error) = builder.add(&gitignore_path) {
        log::warn!("Failed to load .gitignore: {error}");
    }
    match builder.build() {
        Ok(gitignore) => {
            if gitignore_exists {
                log::info!("Loaded .gitignore to filter file change events");
            }
            gitignore
        }
        Err(error) => {
            log::warn!("Failed to build gitignore matcher: {error}");
            GitignoreBuilder::new(root)
                .build()
                .unwrap_or_else(|_error: ignore::Error| Gitignore::empty())
        }
    }
}

/// Extracts the value of `--out-name` from the wasm-pack arguments.
///
/// Returns `None` if `--out-name` is not specified.
///
/// # Arguments
///
/// - `&[String]` - The wasm-pack arguments to search.
///
/// # Returns
///
/// - `Option<String>` - The value of `--out-name` if found.
fn extract_out_name(wasm_pack_args: &[String]) -> Option<String> {
    let mut iter: Iter<'_, String> = wasm_pack_args.iter();
    while let Some(arg) = iter.next() {
        if arg == OUT_NAME_ARG {
            return iter.next().cloned();
        }
        if let Some(value) = arg.strip_prefix(&format!("{OUT_NAME_ARG}=")) {
            return Some(value.to_string());
        }
    }
    None
}

/// Extracts the value of `--out-dir` from the wasm-pack arguments.
///
/// Returns `None` if `--out-dir` is not specified.
///
/// # Arguments
///
/// - `&[String]` - The wasm-pack arguments to search.
///
/// # Returns
///
/// - `Option<String>` - The value of `--out-dir` if found.
fn extract_out_dir(wasm_pack_args: &[String]) -> Option<String> {
    let mut iter: Iter<'_, String> = wasm_pack_args.iter();
    while let Some(arg) = iter.next() {
        if arg == OUT_DIR_ARG {
            return iter.next().cloned();
        }
        if let Some(value) = arg.strip_prefix(&format!("{OUT_DIR_ARG}=")) {
            return Some(value.to_string());
        }
    }
    None
}

/// Resolves the output JS filename for HTML generation.
///
/// Uses `--out-name` from wasm-pack args if specified,
/// otherwise reads the crate name from `Cargo.toml` `[package] name` field
/// and replaces hyphens with underscores (matching wasm-pack behavior).
/// Appends `.js` extension to form the complete JS filename.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing crate_path and wasm_pack_args.
///
/// # Returns
///
/// - `String` - The resolved JS filename with `.js` extension (e.g. `euv_example.js`).
pub fn resolve_out_name(args: &ModeArgs) -> String {
    let name: String = if let Some(out_name) = extract_out_name(args.get_wasm_pack_args()) {
        out_name.replace(STR_HYPHEN, STR_UNDERSCORE)
    } else {
        let cargo_toml_path: PathBuf = args.get_crate_path().join(CARGO_TOML_FILE_NAME);
        read_crate_name_from_toml(&cargo_toml_path)
            .unwrap_or_else(|| {
                args.get_crate_path()
                    .file_name()
                    .unwrap_or_default()
                    .to_string_lossy()
                    .to_string()
            })
            .replace(STR_HYPHEN, STR_UNDERSCORE)
    };
    format!("{name}{JS_EXTENSION}")
}

/// Reads the `name` field from a Cargo.toml file.
///
/// Parses the file line-by-line looking for `name = "..."` within the `[package]` section.
///
/// # Arguments
///
/// - `&Path` - The path to the Cargo.toml file.
///
/// # Returns
///
/// - `Option<String>` - The crate name if found.
fn read_crate_name_from_toml(path: &Path) -> Option<String> {
    let content: String = sync_read_to_string(path).ok()?;
    let mut in_package: bool = false;
    for line in content.lines() {
        let trimmed: &str = line.trim();
        if trimmed.starts_with('[') {
            in_package = trimmed == "[package]";
            continue;
        }
        if in_package
            && trimmed.starts_with("name")
            && let Some(value) = trimmed.strip_prefix("name")
        {
            let value: &str = value.trim().strip_prefix('=')?.trim();
            let value: &str = value.strip_prefix('"')?.strip_suffix('"')?;
            return Some(value.to_string());
        }
    }
    None
}

/// Computes the relative path from a base directory to a target directory.
///
/// Compares the component sequences of both paths to find the common prefix,
/// then emits `..` for each remaining base component followed by the remaining
/// target components.
///
/// # Arguments
///
/// - `&Path` - The base directory path.
/// - `&Path` - The target directory path.
///
/// # Returns
///
/// - `PathBuf` - The relative path from base to target.
fn compute_relative_path(base: &Path, target: &Path) -> PathBuf {
    let base_components: Vec<Component> = base.components().collect();
    let target_components: Vec<Component> = target.components().collect();
    let common_len: usize = base_components
        .iter()
        .zip(target_components.iter())
        .take_while(
            |(base_component, target_component): &(&Component, &Component)| {
                base_component == target_component
            },
        )
        .count();
    let mut result: PathBuf = PathBuf::new();
    for _ in &base_components[common_len..] {
        result.push("..");
    }
    for component in &target_components[common_len..] {
        if let Component::Normal(os_str) = component {
            result.push(os_str);
        }
    }
    result
}

/// Resolves the serving root directory for the development server.
///
/// When the output directory is inside the www directory, returns the resolved www directory.
/// When the output directory is outside the www directory, returns the parent of the output directory
/// so that `index.html` and WASM artifacts are co-located under the same serving root.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing crate_path, www_dir, wasm_pack_args.
///
/// # Returns
///
/// - `PathBuf` - The resolved serving root directory.
pub async fn resolve_serving_root(args: &ModeArgs) -> PathBuf {
    let www_absolute: PathBuf = args.get_crate_path().join(args.get_www_dir());
    let out_dir_absolute: PathBuf = resolve_out_dir(args);
    if out_dir_absolute.strip_prefix(&www_absolute).is_ok() {
        resolve_www_dir(&www_absolute).await
    } else {
        out_dir_absolute
            .parent()
            .map(|p: &Path| p.to_path_buf())
            .unwrap_or_else(|| www_absolute)
    }
}

/// Resolves the serving route prefix relative to the crate path.
///
/// Returns the forward-slash-separated path of the serving root relative to the crate path.
/// Used for server route registration and URL display.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing crate_path, www_dir, wasm_pack_args.
///
/// # Returns
///
/// - `String` - The serving route prefix (e.g. `www` or `wwws`).
pub fn resolve_serving_route_prefix(args: &ModeArgs) -> String {
    let www_absolute: PathBuf = args.get_crate_path().join(args.get_www_dir());
    let out_dir_absolute: PathBuf = resolve_out_dir(args);
    let serving_root: PathBuf = if out_dir_absolute.strip_prefix(&www_absolute).is_ok() {
        www_absolute
    } else {
        out_dir_absolute
            .parent()
            .map(|p: &Path| p.to_path_buf())
            .unwrap_or_else(|| www_absolute)
    };
    serving_root
        .strip_prefix(args.get_crate_path())
        .map(|rel: &Path| {
            rel.to_string_lossy()
                .replace(CHAR_SLASH_BACK, STR_SLASH_FORWARD)
        })
        .unwrap_or_else(|_| {
            args.get_www_dir()
                .replace(CHAR_SLASH_BACK, STR_SLASH_FORWARD)
        })
}

/// Resolves the JS import path for HTML generation.
///
/// Computes the relative path from the serving root to the output directory,
/// then appends the JS filename (from `resolve_out_name`, which includes `.js`)
/// to form the full import path (e.g. `./pkg/euv.js` or `./pksg/cc.js`).
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing crate_path, www_dir, wasm_pack_args.
///
/// # Returns
///
/// - `String` - The resolved JS import path relative to the serving root.
pub fn resolve_import_path(args: &ModeArgs) -> String {
    let out_name: String = resolve_out_name(args);
    let www_absolute: PathBuf = args.get_crate_path().join(args.get_www_dir());
    let out_dir_absolute: PathBuf = resolve_out_dir(args);
    let serving_root: PathBuf = if out_dir_absolute.strip_prefix(&www_absolute).is_ok() {
        www_absolute
    } else {
        out_dir_absolute
            .parent()
            .map(|p: &Path| p.to_path_buf())
            .unwrap_or_else(|| www_absolute)
    };
    let relative: PathBuf = compute_relative_path(&serving_root, &out_dir_absolute);
    let mut components: Vec<String> = relative
        .components()
        .filter_map(|component: Component| match component {
            Component::Normal(os_str) => os_str.to_str().map(|text: &str| text.to_string()),
            Component::ParentDir => Some(PARENT_DIR.to_string()),
            _ => None,
        })
        .collect();
    components.push(out_name);
    format!("{RELATIVE_PATH_PREFIX}{}", components.join(PATH_SEPARATOR))
}

/// Resolves the output directory for wasm-pack artifacts.
///
/// Uses `--out-dir` from wasm-pack args if specified,
/// otherwise defaults to `{www_dir}/pkg` so that build artifacts
/// are placed directly inside the www directory served
/// by the development server.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing crate_path, www_dir, and wasm_pack_args.
///
/// # Returns
///
/// - `PathBuf` - The resolved output directory (absolute if crate_path is joined).
pub fn resolve_out_dir(args: &ModeArgs) -> PathBuf {
    let out_dir_path: PathBuf = PathBuf::from(
        extract_out_dir(args.get_wasm_pack_args())
            .unwrap_or_else(|| format!("{}/{PKG_DIR_NAME}", args.get_www_dir())),
    );
    if out_dir_path.is_absolute() {
        out_dir_path
    } else {
        args.get_crate_path().join(&out_dir_path)
    }
}

/// Executes a build-only pipeline: formats euv macros, cleans output directory,
/// builds WASM, and generates HTML.
///
/// Unlike `run_build_pipeline`, this cleans the output directory before building
/// and skips reload notifications — only the essential WASM build artifacts are kept.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments.
///
/// # Returns
///
/// - `Result<(), EuvError>` - Indicates success or failure of the build.
pub async fn run_build_only_pipeline(args: &ModeArgs) -> Result<(), EuvError> {
    let src_path: PathBuf = args.get_crate_path().join(SRC_DIR_NAME);
    if let Err(error) = format_dir(&src_path, FmtMode::Write).await {
        log::warn!("euv fmt error: {error}");
    }
    let out_dir: PathBuf = resolve_out_dir(args);
    clean_out_dir(&out_dir).await;
    build_wasm(args).await?;
    log::info!("WASM build completed successfully");
    let html_config: HtmlConfig = HtmlConfig::new(
        resolve_serving_root(args).await,
        resolve_import_path(args),
        resolve_build_mode(args) == BuildMode::Release,
        args.try_get_index_html().clone(),
        false,
    );
    generate_html(&html_config).await?;
    Ok(())
}

/// Cleans the output directory before a fresh build.
///
/// Removes all files and subdirectories within the output directory
/// so that stale artifacts from previous builds do not remain.
/// The directory itself is preserved (recreated if missing).
///
/// # Arguments
///
/// - `&Path` - The output directory to clean.
pub async fn clean_out_dir(out_dir: &Path) {
    let mut entries: ReadDir = match read_dir(out_dir).await {
        Ok(dir) => dir,
        Err(_) => return,
    };
    while let Ok(Some(entry)) = entries.next_entry().await {
        let path: PathBuf = entry.path();
        if path.is_dir() {
            if let Err(error) = remove_dir_all(&path).await {
                log::warn!("Failed to remove directory '{}': {error}", path.display());
            }
        } else if let Err(error) = remove_file(&path).await {
            log::warn!("Failed to remove file '{}': {error}", path.display());
        }
    }
}

/// Executes a full build pipeline: euv fmt, build wasm, generate HTML.
/// Notifies the reload channel on build success or failure.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments.
/// - `Option<&broadcast::Sender<ReloadEvent>>` - Optional reload channel for notifying clients.
///
/// # Returns
///
/// - `Result<String, EuvError>` - The generated HTML with reload script injected on success.
pub async fn run_build_pipeline(
    args: &ModeArgs,
    reload_tx: Option<&broadcast::Sender<ReloadEvent>>,
) -> Result<String, EuvError> {
    let src_path: PathBuf = args.get_crate_path().join(SRC_DIR_NAME);
    if let Err(error) = format_dir(&src_path, FmtMode::Write).await {
        log::warn!("euv fmt error: {error}");
    }
    match build_wasm(args).await {
        Ok(()) => {
            log::info!("WASM build completed successfully");
            if let Some(sender) = reload_tx {
                let _: Result<usize, tokio::sync::broadcast::error::SendError<ReloadEvent>> =
                    sender.send(ReloadEvent::Reload);
            }
        }
        Err(error) => {
            log::error!("WASM build failed: {error}");
            if let Some(sender) = reload_tx {
                let _: Result<usize, tokio::sync::broadcast::error::SendError<ReloadEvent>> =
                    sender.send(ReloadEvent::Error(error.to_string()));
            }
        }
    }
    let html_config: HtmlConfig = HtmlConfig::new(
        resolve_serving_root(args).await,
        resolve_import_path(args),
        resolve_build_mode(args) == BuildMode::Release,
        args.try_get_index_html().clone(),
        true,
    );
    let html: String = generate_html(&html_config).await?;
    Ok(html)
}

/// Watches source files and triggers WASM builds.
///
/// # Arguments
///
/// - `Arc<AppState>` - The shared application state.
///
/// # Returns
///
/// - `Result<(), EuvError>` - Indicates success or failure of the file watcher.
pub(crate) async fn watch_and_build(state: Arc<AppState>) -> Result<(), EuvError> {
    let crate_path: PathBuf = state.get_args().get_crate_path().clone();
    let src_path: PathBuf = crate_path.join(SRC_DIR_NAME);
    let gitignore: Gitignore = build_gitignore(&crate_path).await;
    let (tx, mut rx): (Sender<Event>, Receiver<Event>) = channel(32);
    let mut watcher: RecommendedWatcher = RecommendedWatcher::new(
        move |result: Result<Event, notify::Error>| {
            if let Ok(event) = result {
                let _: Result<(), tokio::sync::mpsc::error::SendError<Event>> =
                    tx.blocking_send(event);
            }
        },
        Config::default(),
    )?;
    watcher.watch(&src_path, RecursiveMode::Recursive)?;
    log::info!("Watching {} for changes...", src_path.display());
    let mut debounce: Interval = interval(Duration::from_millis(500));
    debounce.tick().await;
    while let Some(event) = rx.recv().await {
        let filtered_paths: Vec<String> = event
            .paths
            .iter()
            .filter(|path: &&PathBuf| !gitignore.matched(*path, path.is_dir()).is_ignore())
            .map(|path: &PathBuf| path.display().to_string())
            .collect();
        if filtered_paths.is_empty() {
            continue;
        }
        log::warn!("File change detected: {}", filtered_paths.join(", "));
        debounce.reset();
        sleep(Duration::from_millis(300)).await;
        let mut building: RwLockWriteGuard<bool> = state.get_is_building().write().await;
        if *building {
            continue;
        }
        *building = true;
        drop(building);
        let state_for_build: Arc<AppState> = Arc::clone(&state);
        spawn(async move {
            let args: ModeArgs = state_for_build.get_args().clone();
            let reload_tx: broadcast::Sender<ReloadEvent> = state_for_build.get_reload_tx().clone();
            match run_build_pipeline(&args, Some(&reload_tx)).await {
                Ok(html) => {
                    let mut content: RwLockWriteGuard<String> =
                        state_for_build.get_html_content().write().await;
                    *content = html;
                }
                Err(error) => {
                    log::error!("Build pipeline error: {error}");
                }
            }
            let mut building: RwLockWriteGuard<bool> =
                state_for_build.get_is_building().write().await;
            *building = false;
        });
    }
    Ok(())
}

/// Runs wasm-pack build for the target crate.
///
/// All arguments in `args.wasm_pack_args` are transparently forwarded
/// to `wasm-pack build`. If `--out-dir` is not specified by the user,
/// `--out-dir {www_dir}/pkg` is automatically injected so that build artifacts
/// are placed inside the www directory served by the development server.
///
/// # Arguments
///
/// - `&ModeArgs` - The CLI arguments containing crate_path, www_dir, and wasm_pack_args.
///
/// # Returns
///
/// - `Result<(), EuvError>` - Indicates success or failure of the wasm-pack build.
pub async fn build_wasm(args: &ModeArgs) -> Result<(), EuvError> {
    let build_mode: BuildMode = resolve_build_mode(args);
    let build_mode_flag: &str = build_mode_to_flag(build_mode);
    let filtered_args: Vec<String> = filter_euv_args(args.get_wasm_pack_args());
    let has_existing_build_mode: bool = has_build_mode_flag(&filtered_args);
    let default_out_dir: String = format!("{}/{PKG_DIR_NAME}", args.get_www_dir());
    let mut command: Command = Command::new(WASM_PACK_COMMAND);
    command.arg(WASM_PACK_BUILD_SUBCOMMAND);
    if !has_existing_build_mode {
        command.arg(build_mode_flag);
    }
    command
        .args(&filtered_args)
        .env(RUST_MIN_STACK_ENV, RUST_MIN_STACK_VALUE);
    let has_out_dir: bool = extract_out_dir(&filtered_args).is_some();
    if !has_out_dir {
        command.arg(OUT_DIR_ARG).arg(&default_out_dir);
    }
    let has_target: bool = filtered_args
        .iter()
        .any(|arg: &String| arg == TARGET_ARG || arg.starts_with(&format!("{TARGET_ARG}=")));
    if !has_target {
        command.arg(TARGET_ARG).arg(TARGET_WEB);
    }
    command.current_dir(args.get_crate_path());
    command.stdout(Stdio::piped()).stderr(Stdio::piped());
    let display_args: Vec<String> = (if has_existing_build_mode {
        filtered_args.to_vec()
    } else {
        once(build_mode_flag.to_string())
            .chain(filtered_args.iter().cloned())
            .collect::<Vec<String>>()
    })
    .into_iter()
    .chain(if has_out_dir {
        Vec::new()
    } else {
        vec![OUT_DIR_ARG.to_string(), default_out_dir.clone()]
    })
    .chain(if has_target {
        Vec::new()
    } else {
        vec![TARGET_ARG.to_string(), TARGET_WEB.to_string()]
    })
    .collect();
    let out_dir_absolute: PathBuf = resolve_out_dir(args);
    create_dir_all(&out_dir_absolute)
        .await
        .map_err(|error: io::Error| EuvError::IoPath {
            message: String::from("Failed to create output directory"),
            path: out_dir_absolute.clone(),
            error,
        })?;
    log::info!(
        "Running: {WASM_PACK_COMMAND} {WASM_PACK_BUILD_SUBCOMMAND} {} ...",
        display_args.join(" ")
    );
    let output: Output = command
        .output()
        .await
        .map_err(|error: io::Error| EuvError::Io {
            message: String::from("Failed to execute wasm-pack"),
            error,
        })?;
    let stdout: String = String::from_utf8_lossy(&output.stdout).to_string();
    let stderr: String = String::from_utf8_lossy(&output.stderr).to_string();
    if args.get_no_gitignore() {
        let gitignore_path: PathBuf = out_dir_absolute.join(GITIGNORE_FILE_NAME);
        if gitignore_path.exists()
            && let Err(error) = remove_file(&gitignore_path).await
        {
            log::warn!("Failed to remove '{}': {error}", gitignore_path.display());
        }
    }
    for line in stdout.lines().filter(|line: &&str| !line.is_empty()) {
        log::info!("{line}");
    }
    if output.status.success() {
        for line in stderr.lines().filter(|line: &&str| !line.is_empty()) {
            log::info!("{line}");
        }
    } else {
        for line in stderr.lines().filter(|line: &&str| !line.is_empty()) {
            log::error!("{line}");
        }
        return Err(EuvError::Message(String::from("wasm-pack build failed")));
    }
    Ok(())
}

/// Prints the startup banner and command information.
///
/// # Arguments
///
/// - `Action` - The action to perform (run or build).
pub fn print_banner(action: Action) {
    let version: &str = env!("CARGO_PKG_VERSION");
    if version.is_empty() {
        log::warn!("Failed to parse version from root Cargo.toml");
    } else {
        log::info!("euv v{version}");
    }
    let action_name: &str = match action {
        Action::Run => ACTION_RUN,
        Action::Build => ACTION_BUILD,
    };
    log::info!("Mode: {action_name}");
    log::info!(
        "Use .gitignore to filter file change events; pass --no-gitignore to remove .gitignore from output"
    );
}

/// Enumerates all network interface IP addresses and prints each server URL
/// along with its corresponding QR code to the console.
///
/// Includes both loopback (127.0.0.1) and all private/public IPv4 addresses
/// bound to the host's network interfaces. Each address produces one URL line
/// followed by a Unicode QR code rendered with half-block characters,
/// where every line carries the standard log prefix (timestamp + level).
///
/// # Arguments
///
/// - `&ServerUrlConfig` - The server URL configuration.
pub(crate) fn print_server_urls(config: &ServerUrlConfig) {
    let port: u16 = config.get_port();
    let route_prefix: &str = config.get_route_prefix();
    let index_html_file_name: &str = config.get_index_html_file_name();
    let mut addresses: Vec<IpAddr> = Vec::new();
    match if_addrs::get_if_addrs() {
        Ok(interfaces) => {
            for interface in interfaces {
                let ip: IpAddr = interface.addr.ip();
                if !addresses.contains(&ip) {
                    addresses.push(ip);
                }
            }
        }
        Err(error) => {
            log::warn!("Failed to enumerate network interfaces: {error}");
        }
    }
    if addresses.is_empty() {
        addresses.push(IpAddr::V4(Ipv4Addr::LOCALHOST));
    }
    for ip in addresses {
        let host: String = match ip {
            IpAddr::V6(_) => format!("[{ip}]"),
            IpAddr::V4(_) => format!("{ip}"),
        };
        let url: String =
            format!("{HTTP_SCHEME}://{host}:{port}/{route_prefix}/{index_html_file_name}");
        log::info!("Server: {url}");
        match QrCode::new(url.as_str()) {
            Ok(code) => {
                let string: String = code.render::<Dense1x2>().quiet_zone(false).build();
                for line in string.lines() {
                    log::info!("{line}");
                }
            }
            Err(error) => {
                log::warn!("Failed to generate QR code: {error}");
            }
        }
    }
}

/// Reads the wasm-bindgen JS bridge produced by `wasm-pack build
/// --target web` and returns a synchronous IIFE that inlines the bridge
/// and its snippet modules, fetches the wasm module from `wasm_url`,
/// then calls `main()` once the instance is ready.
///
/// The bridge's own top-level `import` lines (the tiny snippet helpers
/// under `./snippets/`) are stripped and their bodies inlined, so the
/// result is self-contained and the browser makes zero extra requests
/// for the bridge file.
/// # Arguments
///
/// - `&Path` - Directory holding the wasm-pack output.
/// - `&str` - File name of the generated JS bridge inside it.
/// - `&str` - URL the page will fetch the `.wasm` module from.
///
/// # Returns
///
/// - `Result<String, EuvError>` - The IIFE source, or an error if the
///   bridge or one of its snippet imports cannot be read.
pub(crate) async fn build_inline_bridge(
    pkg_dir: &Path,
    js_name: &str,
    wasm_url: &str,
) -> Result<String, EuvError> {
    let js_path: PathBuf = pkg_dir.join(js_name);
    let bridge_source: String =
        read_to_string(&js_path)
            .await
            .map_err(|error: io::Error| EuvError::IoPath {
                message: String::from("Failed to read wasm-bindgen JS bridge"),
                path: js_path.clone(),
                error,
            })?;
    let snippet_bodies: String = collect_snippet_bodies(&bridge_source, pkg_dir).await?;
    let stripped: String = strip_module_imports(&bridge_source);
    let js_only: String = strip_trailing_module_exports(&stripped);
    let wasm_url_json: String = serde_json_wasm_url(wasm_url);
    Ok(format!(
        "(function() {{\n\
         {snippet_bodies}\n\
         {js_only}\n\
         var __euv_wasm_url = {wasm_url_json};\n\
         if (typeof __wbg_init === 'function') {{\n\
         var __euv_base = (document.querySelector('base[href]') && document.baseURI) || location.href;\n         __wbg_init(new URL(__euv_wasm_url, __euv_base).toString()).then(function() {{\n\
         if (typeof main === 'function') main();\n\
         }}).catch(function(e) {{ console.error('[euv] inline bridge init failed:', e); }});\n\
         }} else if (typeof initSync === 'function') {{\n\
         initSync();\n\
         if (typeof main === 'function') main();\n\
         }} else {{\n\
         console.error('[euv] inline bridge: no __wbg_init or initSync exported');\n\
         }}\n\
         }})();\n"
    ))
}

/// Returns the inline `<script>` body to use when JS bridge inlining is
/// disabled, restoring the classic module import as a fallback during
/// wasm-pack output transitions.
///
/// # Arguments
///
/// - `&str` - The module import path the browser should resolve.
///
/// # Returns
///
/// - `String` - The `<script>` body, ready to be embedded in the page.
pub(crate) fn build_module_fallback_bridge(import_path: &str) -> String {
    format!(
        "    import init, {{ main }} from '{import_path}';\n    \
         await init();\n    \
         main();\n"
    )
}

/// Returns `true` when the inline bridge should be skipped.
///
/// # Returns
///
/// - `bool` - `true` if the env var is set to a non-empty value.
pub(crate) fn inline_bridge_disabled() -> bool {
    matches!(var(EUV_NO_INLINE_BRIDGE_ENV), Ok(value) if !value.is_empty())
}

/// Collects the source of every module the bridge imports, inlined in
/// dependency order, and materialises each namespace import as a `var`
/// object so the bridge body keeps working without the module graph.
///
/// # Arguments
///
/// - `&str` - The bridge source whose `import` lines drive the scan.
/// - `&Path` - Directory holding the wasm-pack output, used to resolve
///   each relative specifier.
///
/// # Returns
///
/// - `Result<String, EuvError>` - The concatenated snippet bodies, or an
///   error if a specifier escapes the package directory.
async fn collect_snippet_bodies(bridge_source: &str, pkg_dir: &Path) -> Result<String, EuvError> {
    let mut bodies: String = String::new();
    let mut namespace_imports: Vec<NamespaceImport> = Vec::new();
    for line in bridge_source.lines() {
        let trimmed: &str = line.trim();
        if !trimmed.starts_with("import ") {
            continue;
        }
        let rest: &str = match trimmed.strip_prefix("import ") {
            Some(value) => value,
            None => continue,
        };
        let spec: &str = match extract_import_spec(rest) {
            Some(value) => value,
            None => continue,
        };
        if is_namespace_import(rest)
            && let Some(alias) = extract_namespace_alias(rest)
        {
            namespace_imports.push(NamespaceImport {
                alias: alias.to_string(),
                spec: spec.to_string(),
            });
        }
        let body: Option<String> = read_snippet_module(pkg_dir, spec).await?;
        if let Some(body) = body {
            if !bodies.is_empty() {
                bodies.push('\n');
            }
            bodies.push_str(&body);
        }
    }
    for ns in &namespace_imports {
        let snippet_path: PathBuf = resolve_snippet_path(pkg_dir, &ns.spec)?;
        let exports: Vec<String> = if snippet_path.exists() {
            let raw: String = read_to_string(&snippet_path)
                .await
                .map_err(|error: io::Error| EuvError::IoPath {
                    message: String::from(
                        "Failed to read wasm-pack snippet module for namespace export scan",
                    ),
                    path: snippet_path.clone(),
                    error,
                })?;
            extract_exported_function_names(&raw)
        } else {
            Vec::new()
        };
        if !bodies.is_empty() {
            bodies.push('\n');
        }
        bodies.push_str(&format!("var {} = {{", ns.alias));
        for (i, name) in exports.iter().enumerate() {
            if i > 0 {
                bodies.push(',');
            }
            bodies.push_str(name);
            bodies.push(':');
            bodies.push_str(name);
        }
        bodies.push_str("};\n");
    }
    Ok(bodies)
}

/// Scans a snippet module for `export function NAME(` declarations and
/// returns their names. The IIFE relies on function declarations being
/// hoisted, so these names resolve to the same bindings that
/// wasm-bindgen's `__wbg_get_imports` expects.
///
/// # Arguments
///
/// - `&str` - The snippet module source to scan.
///
/// # Returns
///
/// - `Vec<String>` - Every exported function name, in source order.
pub fn extract_exported_function_names(source: &str) -> Vec<String> {
    let mut names: Vec<String> = Vec::new();
    for line in source.lines() {
        let trimmed: &str = line.trim();
        if let Some(rest) = trimmed.strip_prefix("export function ") {
            let name_end: usize =
                match rest.find(|c: char| !c.is_alphanumeric() && c != '_' && c != '$') {
                    Some(value) => value,
                    None => rest.len(),
                };
            let name: &str = &rest[..name_end];
            if !name.is_empty() {
                names.push(name.to_string());
            }
        }
    }
    names
}

/// Returns `true` when the clause is a namespace import (`import * as X`).
///
/// # Arguments
///
/// - `&str` - The import clause, without its leading `import` keyword.
///
/// # Returns
///
/// - `bool` - `true` for `* as <alias>` clauses.
pub fn is_namespace_import(rest: &str) -> bool {
    rest.trim_start().starts_with('*')
}

/// Extracts the local binding a namespace import introduces.
///
/// # Arguments
///
/// - `&str` - The import clause, without its leading `import` keyword.
///
/// # Returns
///
/// - `Option<&str>` - The alias, or `None` if the clause is not a
///   namespace import or carries no name.
pub fn extract_namespace_alias(rest: &str) -> Option<&str> {
    let rest: &str = rest.trim_end_matches(';').trim();
    if !rest.starts_with('*') {
        return None;
    }
    let rest: &str = rest.strip_prefix('*')?.trim();
    let rest: &str = rest.strip_prefix("as")?.trim();
    let end: usize = match rest.find(|c: char| !c.is_alphanumeric() && c != '_' && c != '$') {
        Some(value) => value,
        None => rest.len(),
    };
    let alias: &str = &rest[..end];
    if alias.is_empty() { None } else { Some(alias) }
}

/// Extracts the relative specifier an import clause resolves against.
///
/// Bare specifiers are rejected: only `./` and `../` targets are inlined,
/// because anything else would drag in a module this code does not
/// control.
///
/// # Arguments
///
/// - `&str` - The import clause, without its leading `import` keyword.
///
/// # Returns
///
/// - `Option<&str>` - The specifier with its quotes stripped, or `None`
///   when the clause has no `from` or names a non-relative module.
pub fn extract_import_spec(rest: &str) -> Option<&str> {
    let rest: &str = rest.trim_end_matches(';').trim();
    let from_idx: usize = rest.find(" from ")?;
    let spec_part: &str = rest[from_idx + " from ".len()..].trim();
    let spec: &str = spec_part
        .trim_start_matches('\'')
        .trim_start_matches('"')
        .trim_end_matches('\'')
        .trim_end_matches('"');
    if spec.starts_with("./") || spec.starts_with("../") {
        Some(spec)
    } else {
        None
    }
}

/// Reads one snippet module and returns its body with the `export` keyword
/// stripped, so it can be concatenated into the IIFE as a plain
/// declaration.
///
/// # Arguments
///
/// - `&Path` - Directory holding the wasm-pack output.
/// - `&str` - Relative specifier of the snippet to read.
///
/// # Returns
///
/// - `Result<Option<String>, EuvError>` - The stripped body, `None` if the
///   file does not exist, or an error if it cannot be read or decoded.
async fn read_snippet_module(pkg_dir: &Path, spec: &str) -> Result<Option<String>, EuvError> {
    let snippet_path: PathBuf = resolve_snippet_path(pkg_dir, spec)?;
    if !snippet_path.exists() {
        return Ok(None);
    }
    let bytes: Vec<u8> =
        read(&snippet_path)
            .await
            .map_err(|error: io::Error| EuvError::IoPath {
                message: String::from("Failed to read wasm-pack snippet module"),
                path: snippet_path.clone(),
                error,
            })?;
    let raw: String = String::from_utf8(bytes).map_err(|error: FromUtf8Error| EuvError::Utf8 {
        message: String::from("Snippet module is not valid UTF-8"),
        error,
    })?;
    Ok(Some(strip_snippet_export(&raw)))
}

/// Resolves a relative specifier to a path inside `pkg_dir`.
///
/// # Arguments
///
/// - `&Path` - Directory holding the wasm-pack output.
/// - `&str` - Relative specifier taken from the bridge's import clause.
///
/// # Returns
///
/// - `Result<PathBuf, EuvError>` - The resolved path, or an error if the
///   specifier climbs above `pkg_dir`.
fn resolve_snippet_path(pkg_dir: &Path, spec: &str) -> Result<PathBuf, EuvError> {
    let base: &str = spec.trim_start_matches('.').trim_start_matches('/');
    let mut path: PathBuf = pkg_dir.to_path_buf();
    for segment in base.split('/') {
        if segment.is_empty() || segment == "." {
            continue;
        }
        if segment == ".." {
            return Err(EuvError::Message(String::from(
                "Snippet import spec escapes pkg directory",
            )));
        }
        path.push(segment);
    }
    Ok(path)
}

/// Rewrites a snippet module's source into bare declarations by removing
/// the `export ` prefix from every line that carries one.
///
/// # Arguments
///
/// - `&str` - The snippet module source.
///
/// # Returns
///
/// - `String` - The same source with the `export ` keywords removed.
fn strip_snippet_export(raw: &str) -> String {
    let mut out: String = String::with_capacity(raw.len());
    for line in raw.lines() {
        let trimmed: &str = line.trim();
        if trimmed.starts_with("export ") {
            if let Some(rest) = trimmed.strip_prefix("export ") {
                out.push_str(rest);
                out.push('\n');
            }
        } else {
            out.push_str(line);
            out.push('\n');
        }
    }
    out
}

/// Removes the bridge's own `import` lines and any line referencing
/// `import.meta.url`, since the inlined IIFE has neither.
///
/// # Arguments
///
/// - `&str` - The bridge source.
///
/// # Returns
///
/// - `String` - The source with those lines dropped.
fn strip_module_imports(source: &str) -> String {
    let mut out: String = String::with_capacity(source.len());
    for line in source.lines() {
        let trimmed: &str = line.trim();
        if trimmed.starts_with("import ") {
            continue;
        }
        if trimmed.contains("import.meta.url") {
            continue;
        }
        out.push_str(line);
        out.push('\n');
    }
    out
}

/// Removes the bridge's trailing `export { ... }` and `export function`
/// lines, turning each exported alias into the assignment that keeps the
/// local function reachable under its exported name.
///
/// # Arguments
///
/// - `&str` - The bridge source, after [`strip_module_imports`].
///
/// # Returns
///
/// - `String` - The source with its module-level export syntax removed.
fn strip_trailing_module_exports(source: &str) -> String {
    let mut out: String = String::with_capacity(source.len());
    for line in source.lines() {
        let trimmed: &str = line.trim();
        if trimmed.starts_with("export ") && trimmed.contains('{') && trimmed.contains('}') {
            let inner: &str = &trimmed["export ".len()..];
            let stripped: &str = match inner.strip_prefix('{') {
                Some(value) => value,
                None => {
                    out.push_str(line);
                    out.push('\n');
                    continue;
                }
            };
            let close: usize = match stripped.rfind('}') {
                Some(value) => value,
                None => {
                    out.push_str(line);
                    out.push('\n');
                    continue;
                }
            };
            let names_block: &str = &stripped[..close];
            let inlined: String = inline_export_aliases(names_block.trim());
            if !inlined.is_empty() {
                out.push_str(&inlined);
                out.push('\n');
            }
            continue;
        }
        if trimmed.starts_with("export function ") {
            let rest: &str = match trimmed.strip_prefix("export function ") {
                Some(value) => value,
                None => {
                    out.push_str(line);
                    out.push('\n');
                    continue;
                }
            };
            let name_end: usize = match rest.find(|c: char| !c.is_alphanumeric() && c != '_') {
                Some(value) => value,
                None => rest.len(),
            };
            let name: &str = &rest[..name_end];
            if !name.is_empty() {
                out.push_str("function ");
                out.push_str(name);
                out.push_str(&rest[name_end..]);
                out.push('\n');
                continue;
            }
        }
        out.push_str(line);
        out.push('\n');
    }
    out
}

/// Converts the body of an `export { a, b as c }` clause into the
/// assignments that keep each local function reachable under its
/// exported name. Exports of `wasm` are dropped: the IIFE is a plain
/// `<script>`, so there is no `wasm` binding in scope.
///
/// # Arguments
///
/// - `&str` - The comma-separated body between the export braces.
///
/// # Returns
///
/// - `String` - The assignments, one per line, or empty when every alias
///   is a no-op.
fn inline_export_aliases(block: &str) -> String {
    let mut out: String = String::new();
    for entry in block.split(',') {
        let entry: &str = entry.trim();
        if entry.is_empty() {
            continue;
        }
        if let Some((original, exported)) = entry.split_once(" as ") {
            let original: &str = original.trim();
            let exported: &str = exported.trim();
            if original == exported || exported == "default" || original == "wasm" {
                continue;
            }
            out.push_str(exported);
            out.push_str(" = ");
            out.push_str(original);
            out.push_str(";\n");
        }
    }
    out
}

/// Encodes a URL as a JSON string literal, including the surrounding
/// quotes.
///
/// Hand-rolled rather than `serde_json::to_string` because the value is
/// interpolated into a template that is already assembling JavaScript,
/// and the only characters that can appear here are URL characters.
///
/// # Arguments
///
/// - `&str` - The URL to encode.
///
/// # Returns
///
/// - `String` - A quoted, escaped JSON string.
fn serde_json_wasm_url(url: &str) -> String {
    let mut out: String = String::with_capacity(url.len() + 2);
    out.push('"');
    for ch in url.chars() {
        match ch {
            '"' => out.push_str("\\\""),
            '\\' => out.push_str("\\\\"),
            '\n' => out.push_str("\\n"),
            '\r' => out.push_str("\\r"),
            '\t' => out.push_str("\\t"),
            '\u{08}' => out.push_str("\\b"),
            '\u{0C}' => out.push_str("\\f"),
            c if (c as u32) < 0x20 => out.push_str(&format!("\\u{:04x}", c as u32)),
            c => out.push(c),
        }
    }
    out.push('"');
    out
}