day-spec 0.6.2

// Copyright © The Daybrite Project
// SPDX-License-Identifier: MPL-2.0

//! Bundled resources: efficient random read-only access to app-declared data, backed by each
//! toolkit's native resource mechanism (DESIGN.md §18.3).
//!
//! `day build` stages the files declared under a project's `assets/` (and `images/`) into each
//! platform's native resource store, **uncompressed where possible** so the runtime can hand back a
//! zero-copy view. At runtime `resource("name")` returns a [`Resource`] whose bytes are borrowed
//! directly from that store: an mmap of a bundle file on Apple, the NDK `AAssetManager` buffer on
//! Android, `g_resources_lookup_data` on GTK, `QResource::data` on Qt, the rawfile fd on ArkUI.
//!
//! The active backend registers its opener once via [`set_resource_opener`]; if none is registered
//! (desktop dev, host tests, and the Apple backends, whose native mechanism *is* a bundle file) the
//! default opener mmaps the file resolved from `DAY_ASSET_ROOT` or the app bundle.

use std::any::Any;
use std::borrow::Cow;
use std::path::PathBuf;
use std::sync::OnceLock;

// ---------------------------------------------------------------------------
// Typed resource identifiers (§18.5)
//
// `image(...)`, `resource(...)`, and `Font::custom(...)` take these newtypes rather than a bare
// `&str`. Every value is meant to come from a generated `res::images/assets/fonts::…` constant
// (`day-build`), so referencing a resource that isn't bundled is a compile error and the available
// names autocomplete. A string *literal* does not coerce, which is what turns "present" from a
// convention into a guarantee; a name only known at runtime uses the explicit `::dynamic`
// escape hatch (or, for images/assets, `From<String>`).
// ---------------------------------------------------------------------------

macro_rules! resource_name {
    ($(#[$m:meta])* $name:ident, $what:literal) => {
        $(#[$m])*
        #[derive(Clone, Debug, PartialEq, Eq)]
        pub struct $name(Cow<'static, str>);

        impl $name {
            #[doc = concat!("A ", $what, " known at compile time — the form the generated `res::…` constants use.")]
            pub const fn from_static(name: &'static str) -> Self {
                $name(Cow::Borrowed(name))
            }
            #[doc = concat!("Escape hatch for a ", $what, " computed at runtime (no build-time presence guarantee).")]
            pub fn dynamic(name: impl Into<String>) -> Self {
                $name(Cow::Owned(name.into()))
            }
            /// The underlying wire name the backend resolves by.
            pub fn as_str(&self) -> &str {
                &self.0
            }
        }

        // Owned strings convert (dynamic names); a `&str` literal does not, so
        // `image("typo")` / `resource("typo")` fail to compile.
        impl From<String> for $name {
            fn from(s: String) -> Self {
                $name(Cow::Owned(s))
            }
        }

        impl std::fmt::Display for $name {
            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
                f.write_str(&self.0)
            }
        }
    };
}

resource_name!(
    /// The bundled-image name that [`resource()`](crate::resource()) callers resolve by (the file stem).
    ImageName,
    "bundled-image name"
);
resource_name!(
    /// The bundled-data name that [`resource`] resolves by: the file's path relative to
    /// `resource/assets/`, `/`-separated (a top-level file is just its file name, extension
    /// included).
    AssetName,
    "bundled-asset name"
);
resource_name!(
    /// A bundled-asset directory (§18.5): a folder's path relative to `resource/assets/`,
    /// `/`-separated, no trailing slash. The generated `res::assets::…` tree carries one
    /// constant per folder, sharing its module's name: `res::assets::web::minisite` is the
    /// `AssetDir` and `res::assets::web::minisite::index_html` a file within it.
    AssetDir,
    "bundled-asset directory"
);

impl AssetDir {
    /// Name a file under this directory, for [`resource`]: the escape hatch for paths
    /// composed at runtime (`dir.join("posts/1.html")`); prefer the generated file constants
    /// where the path is known.
    pub fn join(&self, rel: &str) -> AssetName {
        AssetName::dynamic(format!("{}/{}", self.as_str(), rel.trim_start_matches('/')))
    }
}
resource_name!(
    /// The bundled-vector name that [`resource()`](crate::resource()) callers resolve by (docs/vectors.md):
    /// the stem of a `resource/vectors/` SVG (or `.symbolset` bundle). Vectors and images share one
    /// per-backend resolution namespace; staging guarantees every vector name resolves as whatever
    /// form that backend loads natively (a VectorDrawable, a catalog entry, a rasterized PNG).
    VectorName,
    "bundled-vector name"
);

/// Vector and image names resolve through the same per-backend channel (nav-item icons, the
/// toolbar's `.image(…)`, `bar_action`, all name-based); this conversion is that shared
/// namespace made explicit.
impl From<VectorName> for ImageName {
    fn from(v: VectorName) -> ImageName {
        ImageName::dynamic(v.as_str().to_owned())
    }
}

/// The family name of a bundled custom font, feeding `Font::custom`. Holds a `&'static str` (so
/// `Font` stays `Copy`); generated `res::fonts::…` constants supply it. The untyped
/// `Font::Custom(&'static str, f64)` variant remains the escape hatch for a family known another way.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct FontFamily(&'static str);

impl FontFamily {
    /// A font family known at compile time: the form the generated `res::fonts::…` constants use.
    pub const fn from_static(family: &'static str) -> Self {
        FontFamily(family)
    }
    /// The underlying family name (what `Font::Custom` carries).
    pub const fn as_str(&self) -> &'static str {
        self.0
    }
}

impl std::fmt::Display for FontFamily {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.0)
    }
}

/// A handle to a bundled resource's bytes with efficient random read-only access.
///
/// The bytes stay valid for the lifetime of the `Resource`: it owns a guard (an mmap, a native
/// `GBytes`/`QResource`/`AAsset` handle, or an owned buffer) that keeps the backing store alive.
/// `Resource` is neither `Send` nor `Sync`; like the rest of the day runtime it is used on the
/// main/UI thread.
pub struct Resource {
    ptr: *const u8,
    len: usize,
    /// Keeps the backing store alive while `ptr`/`len` are borrowed from it.
    _guard: Box<dyn Any>,
}

impl Resource {
    /// Build a `Resource` from a raw byte view plus the guard that owns it. Backends call this from
    /// their opener after obtaining a zero-copy pointer from the native resource API.
    ///
    /// # Safety
    /// `ptr` must point to `len` valid, immutable bytes that remain valid for as long as `guard` is
    /// alive, and `guard` must own (and keep alive) that backing store.
    pub unsafe fn from_raw(ptr: *const u8, len: usize, guard: Box<dyn Any>) -> Resource {
        Resource {
            ptr,
            len,
            _guard: guard,
        }
    }

    /// Build a `Resource` from owned bytes: the copy fallback for backends that cannot expose a
    /// stable pointer into their store (or when a native API only offers a read-into-buffer call).
    pub fn from_vec(bytes: Vec<u8>) -> Resource {
        let boxed: Box<[u8]> = bytes.into_boxed_slice();
        let ptr = boxed.as_ptr();
        let len = boxed.len();
        // Moving the box moves the (fat) pointer, not the heap allocation, so `ptr` stays valid.
        Resource {
            ptr,
            len,
            _guard: Box::new(boxed),
        }
    }

    /// Total byte length of the resource.
    pub fn len(&self) -> usize {
        self.len
    }

    /// Whether the resource is empty.
    pub fn is_empty(&self) -> bool {
        self.len == 0
    }

    /// A zero-copy view of the full contents. Backed directly by the native store (no allocation,
    /// no copy). Wrap in [`std::io::Cursor`] for `Read`/`Seek`-style access.
    pub fn as_slice(&self) -> &[u8] {
        // Safety: `ptr`/`len` describe a valid immutable region kept alive by `_guard`.
        unsafe { std::slice::from_raw_parts(self.ptr, self.len) }
    }

    /// Random-access read: copy up to `buf.len()` bytes starting at `offset` into `buf`, returning
    /// the number of bytes copied (0 if `offset >= len`). A direct `memcpy` from the backing store,
    /// no allocation: the efficient primitive for seeking around a large embedded blob.
    pub fn read_at(&self, offset: usize, buf: &mut [u8]) -> usize {
        let data = self.as_slice();
        if offset >= data.len() {
            return 0;
        }
        let n = buf.len().min(data.len() - offset);
        buf[..n].copy_from_slice(&data[offset..offset + n]);
        n
    }

    /// Copy the full contents into a freshly allocated `Vec`.
    pub fn to_vec(&self) -> Vec<u8> {
        self.as_slice().to_vec()
    }
}

/// A backend's resource opener: maps a declared name (e.g. `"stations.json"`) to its bytes, or
/// `None` if there is no such resource.
pub type ResourceOpener = fn(&str) -> Option<Resource>;

static OPENER: OnceLock<ResourceOpener> = OnceLock::new();

/// Register the active backend's resource opener (Android `AAssetManager`, GTK `GResource`, Qt
/// `QResource`, ArkUI rawfile, …). Called once during backend init. A second call is ignored, so a
/// backend that shares the default file opener need not call this at all.
pub fn set_resource_opener(opener: ResourceOpener) {
    let _ = OPENER.set(opener);
}

/// Open a bundled resource by name for efficient random read-only access.
///
/// Returns `None` if the backend has no resource with that name. Takes an [`AssetName`]: pass a
/// generated `res::assets::…` constant (e.g. `resource(res::assets::stations_json)`) for a checked,
/// guaranteed-present reference, or [`AssetName::dynamic`] for a name known only at runtime.
pub fn resource(name: impl Into<AssetName>) -> Option<Resource> {
    let name = name.into();
    let name = name.as_str();
    match OPENER.get() {
        Some(open) => open(name),
        None => default_open(name),
    }
}

/// The default opener: mmap the file resolved from `DAY_ASSET_ROOT` (dev runs / `day launch`) or the
/// app bundle's `Resources/assets`. This is the Apple backends' native path (a plain bundle file)
/// and the desktop/host-test path.
fn default_open(name: &str) -> Option<Resource> {
    let path = resolve_resource_path(name)?;
    let file = std::fs::File::open(&path).ok()?;
    // Safety: we open read-only and never mutate the mapping; the `Mmap` guard keeps it alive.
    let mmap = unsafe { memmap2::Mmap::map(&file).ok()? };
    let ptr = mmap.as_ptr();
    let len = mmap.len();
    Some(unsafe { Resource::from_raw(ptr, len, Box::new(mmap)) })
}

/// Resolve a data-resource name to an on-disk path: `DAY_ASSET_ROOT` first (dev / CLI launch), then
/// bundle-relative locations next to the executable (macOS `.app`, Linux `share`).
fn resolve_resource_path(name: &str) -> Option<PathBuf> {
    for var in ASSET_ROOT_VARS {
        if let Ok(root) = std::env::var(var) {
            let p = PathBuf::from(root).join(name);
            if p.exists() {
                return Some(p);
            }
        }
    }
    if let Ok(exe) = std::env::current_exe()
        && let Some(dir) = exe.parent()
    {
        for rel in ["../Resources/assets", "Resources/assets", "assets"] {
            let p = dir.join(rel).join(name);
            if p.exists() {
                return Some(p);
            }
        }
    }
    None
}

/// Resolve a data-asset file (a `/`-relative path under `resource/assets/`) to its on-disk
/// location, for consumers that must hand a native API a path rather than bytes: lottie-ios
/// takes a filepath, and its by-name initializer would otherwise look only at the bundle root,
/// where Day stages nothing. Same probe order as [`resource`]: `DAY_ASSET_ROOT` (dev /
/// `day launch`), then the bundle-relative roots.
/// The roots a dev run probes for data assets, in order: the project's own `resource/assets/`,
/// then the tree `day build` stages the assets its pieces ship into (docs/extending.md). A
/// packaged app has one merged `assets/` directory beside the binary and needs neither.
const ASSET_ROOT_VARS: [&str; 2] = ["DAY_ASSET_ROOT", "DAY_PIECE_ASSET_ROOT"];

pub fn resolve_asset_file(name: &str) -> Option<PathBuf> {
    resolve_resource_path(name)
}

/// Resolve a data-asset directory (an [`AssetDir`]'s `/`-relative path) to its on-disk
/// location, for consumers whose local-content channel is a file URL, like the inline web
/// view on the Apple backends (day-piece-webview's docs/webview.md). Same probe order as file
/// resolution: `DAY_ASSET_ROOT` (dev / `day launch`), then the bundle-relative roots.
pub fn resolve_asset_dir(rel: &str) -> Option<PathBuf> {
    // Canonicalized: consumers derive URLs from this path, and a literal `..` segment (the
    // bundle probe below goes through `MacOS/../Resources`) breaks prefix comparison against
    // the standardized URLs engines report back.
    let canon = |p: PathBuf| p.canonicalize().ok().filter(|c| c.is_dir());
    for var in ASSET_ROOT_VARS {
        if let Ok(root) = std::env::var(var)
            && let Some(p) = canon(PathBuf::from(root).join(rel))
        {
            return Some(p);
        }
    }
    if let Ok(exe) = std::env::current_exe()
        && let Some(dir) = exe.parent()
    {
        for base in ["../Resources/assets", "Resources/assets", "assets"] {
            if let Some(p) = canon(dir.join(base).join(rel)) {
                return Some(p);
            }
        }
    }
    None
}

/// Image file extensions probed when an `image("name")` reference omits an extension.
const IMAGE_EXTS: [&str; 8] = ["png", "jpg", "jpeg", "gif", "bmp", "webp", "pdf", "svg"];

/// The suffixes `Vector::weight` appends to a glyph name (docs/vectors.md).
pub const WEIGHT_SUFFIXES: [&str; 2] = ["__light", "__bold"];

/// The base glyph a weight-suffixed name aliases, or `None` if the name carries no suffix.
///
/// Only SF-template sources have true per-weight art, so only they stage `__light`/`__bold`
/// assets. A plain SVG stages once and every weight resolves back to it here, which is what
/// keeps `.weight(…)` from 404-ing on art that has no weight axis, without staging a byte-identical
/// copy of every glyph per weight. (Before this, 38 of Day-Showcase's 39 sources were staged three
/// times over as identical copies.)
pub fn weight_alias(name: &str) -> Option<&str> {
    WEIGHT_SUFFIXES
        .iter()
        .find_map(|s| name.strip_suffix(s))
        .filter(|base| !base.is_empty())
}

/// Resolve an image name to an on-disk file, for the file-loading backends (AppKit/GTK/Qt, and the
/// desktop/dev path). Probes `DAY_IMAGE_ROOT` (the project's `images/` under `day launch`) first,
/// then `DAY_ASSET_ROOT` and the bundle, trying the bare name and, if it has no extension, each
/// known image extension. Native-pipeline backends (iOS `Assets.car`, Android `R`, …) resolve by
/// name through their own store and do not use this.
pub fn resolve_image_file(name: &str) -> Option<PathBuf> {
    let mut roots: Vec<PathBuf> = Vec::new();
    // DAY_VECTOR_RASTER_ROOT: the build-time raster cache for `resource/vectors/`
    // (docs/vectors.md), which is how the file-loading desktop backends resolve a vector name
    // with no native vector pipeline.
    for var in ["DAY_IMAGE_ROOT", "DAY_VECTOR_RASTER_ROOT", "DAY_ASSET_ROOT"] {
        if let Ok(v) = std::env::var(var) {
            roots.push(PathBuf::from(v));
        }
    }
    if let Ok(exe) = std::env::current_exe()
        && let Some(dir) = exe.parent()
    {
        // Packed layouts (docs/vectors.md): `day pack` stages the vector raster cache under
        // `vectors/raster` (inside `Contents/Resources` for a .app, beside the exe for the
        // flat Windows payload), ordered after `images` to mirror the env-root precedence.
        for rel in [
            "../Resources/images",
            "../Resources/vectors/raster",
            "../Resources/assets",
            "images",
            "vectors/raster",
            "assets",
        ] {
            roots.push(dir.join(rel));
        }
    }
    // A weight-suffixed name probes its own art first, then the base glyph it aliases
    // (`weight_alias`): the raster half of the same fallback the SVG resolver does.
    let names: Vec<&str> = match weight_alias(name) {
        Some(base) => vec![name, base],
        None => vec![name],
    };
    let has_ext = std::path::Path::new(name).extension().is_some();
    // Name-major, not root-major: a staged variant found in any root beats the base glyph found in
    // a higher-precedence one, so a template's own `__bold` art is never shadowed by its Regular.
    for (name, root) in names
        .iter()
        .flat_map(|n| roots.iter().map(move |r| (*n, r.clone())))
    {
        let exact = root.join(name);
        if exact.is_file() {
            return Some(exact);
        }
        if !has_ext {
            for ext in IMAGE_EXTS {
                let p = root.join(format!("{name}.{ext}"));
                if p.is_file() {
                    return Some(p);
                }
            }
        }
    }
    None
}

/// Resolve a vector name to its staged glyph SVG, for backends that render SVG natively
/// (docs/vectors.md): `DAY_VECTOR_SVG_ROOT` under `day launch`, else the packed layouts:
/// `Contents/Resources/vectors/svg` in a .app, `vectors/svg` beside a flat-layout exe.
/// `None` (name isn't a vector, or the layout carries no SVGs) means fall back to
/// [`resolve_image_file`]'s raster resolution.
pub fn resolve_vector_svg(name: &str) -> Option<PathBuf> {
    let mut roots: Vec<PathBuf> = Vec::new();
    if let Ok(v) = std::env::var("DAY_VECTOR_SVG_ROOT") {
        roots.push(PathBuf::from(v));
    }
    if let Ok(exe) = std::env::current_exe()
        && let Some(dir) = exe.parent()
    {
        roots.push(dir.join("../Resources/vectors/svg"));
        roots.push(dir.join("vectors/svg"));
    }
    if let Some(found) = roots
        .iter()
        .map(|r| r.join(format!("{name}.svg")))
        .find(|p| p.is_file())
    {
        return Some(found);
    }
    // A weight that stages no art of its own resolves to the base glyph (see `weight_alias`).
    let base = weight_alias(name)?;
    roots
        .into_iter()
        .map(|r| r.join(format!("{base}.svg")))
        .find(|p| p.is_file())
}

/// Resolve a vector name to its staged XAML geometry (docs/vectors.md), the form day-toolkit-winui draws
/// as real `Path` geometry: vector at any size, and tintable by brush at runtime.
/// `DAY_VECTOR_XAML_ROOT` under `day launch`, else `vectors/xaml` beside a flat-layout exe.
/// `None` (name isn't a vector, the art was outside the convertible subset, or the layout
/// carries no geometry) means fall back to [`resolve_image_file`]'s raster resolution.
pub fn resolve_vector_xaml(name: &str) -> Option<PathBuf> {
    let mut roots: Vec<PathBuf> = Vec::new();
    if let Ok(v) = std::env::var("DAY_VECTOR_XAML_ROOT") {
        roots.push(PathBuf::from(v));
    }
    if let Ok(exe) = std::env::current_exe()
        && let Some(dir) = exe.parent()
    {
        roots.push(dir.join("vectors/xaml"));
    }
    if let Some(found) = roots
        .iter()
        .map(|r| r.join(format!("{name}.xamlgeom")))
        .find(|p| p.is_file())
    {
        return Some(found);
    }
    let base = weight_alias(name)?;
    roots
        .into_iter()
        .map(|r| r.join(format!("{base}.xamlgeom")))
        .find(|p| p.is_file())
}

/// Day's own drawing of `sym`, written to a cache file and answered as a path.
///
/// Backends that load icons from files (Qt's SVG icon engine, gdk-pixbuf) can then use the shared
/// fallback through the loader they already have, instead of each growing a way to rasterize a
/// path string. Written once per symbol per process; a failure to write answers `None` and the
/// caller falls back to a label.
pub fn stage_symbol_svg(sym: crate::Symbol) -> Option<PathBuf> {
    let svg = sym.outline_svg()?;
    let dir = std::env::temp_dir().join("day-symbols");
    let file = dir.join(format!("{sym:?}.svg"));
    if file.is_file() {
        return Some(file);
    }
    std::fs::create_dir_all(&dir).ok()?;
    std::fs::write(&file, svg).ok()?;
    Some(file)
}

#[cfg(test)]
mod tests {
    use super::*;

    // One test owns the process env (set_var races across threads), covering both the default
    // data opener and the image-file resolver sequentially.
    #[test]
    fn env_backed_resource_access() {
        let dir = std::env::temp_dir().join(format!("day-res-test-{}", std::process::id()));
        std::fs::create_dir_all(&dir).unwrap();
        let payload: Vec<u8> = (0u8..=255).cycle().take(1000).collect();
        std::fs::write(dir.join("blob.bin"), &payload).unwrap();
        std::fs::write(dir.join("logo.png"), b"x").unwrap();
        // SAFETY: this is the only test that touches the env.
        unsafe {
            std::env::set_var("DAY_ASSET_ROOT", &dir);
            std::env::set_var("DAY_IMAGE_ROOT", &dir);
        }

        // default data opener: whole view + random access + clamping + miss.
        let res = resource(AssetName::from_static("blob.bin")).expect("resource present");
        assert_eq!(res.len(), 1000);
        assert!(!res.is_empty());
        assert_eq!(res.as_slice(), &payload[..]);
        let mut buf = [0u8; 16];
        assert_eq!(res.read_at(500, &mut buf), 16);
        assert_eq!(&buf, &payload[500..516]);
        assert_eq!(res.read_at(995, &mut buf), 5);
        assert_eq!(&buf[..5], &payload[995..1000]);
        assert_eq!(res.read_at(2000, &mut buf), 0);
        assert!(resource(AssetName::from_static("does-not-exist.bin")).is_none());
        // Dynamic names go through the explicit escape hatch.
        assert!(resource(AssetName::dynamic(String::from("nope.bin"))).is_none());

        // image-file resolver: extension inference + exact + miss.
        assert_eq!(resolve_image_file("logo"), Some(dir.join("logo.png")));
        assert_eq!(resolve_image_file("logo.png"), Some(dir.join("logo.png")));
        assert_eq!(resolve_image_file("missing"), None);

        // Weight aliasing (docs/vectors.md): a plain SVG stages one asset, so its `__light` /
        // `__bold` names must resolve back to it rather than miss. `logo` has no weight art of
        // its own, which is exactly the case every non-template glyph is in.
        assert_eq!(weight_alias("logo__bold"), Some("logo"));
        assert_eq!(weight_alias("logo"), None);
        assert_eq!(weight_alias("__bold"), None); // suffix alone aliases nothing
        assert_eq!(resolve_image_file("logo__bold"), Some(dir.join("logo.png")));
        assert_eq!(
            resolve_image_file("logo__light"),
            Some(dir.join("logo.png"))
        );
        // A miss stays a miss: the alias must not invent art for a name with no base either.
        assert_eq!(resolve_image_file("missing__bold"), None);

        // The SVG resolver aliases the same way, and a staged variant still wins over its base.
        let svgs = dir.join("svg");
        std::fs::create_dir_all(&svgs).unwrap();
        std::fs::write(svgs.join("plain.svg"), b"<svg/>").unwrap();
        std::fs::write(svgs.join("tmpl.svg"), b"<svg/>").unwrap();
        std::fs::write(svgs.join("tmpl__bold.svg"), b"<svg/>").unwrap();
        // SAFETY: single test owning the env.
        unsafe { std::env::set_var("DAY_VECTOR_SVG_ROOT", &svgs) };
        assert_eq!(
            resolve_vector_svg("plain__bold"),
            Some(svgs.join("plain.svg"))
        );
        assert_eq!(
            resolve_vector_svg("tmpl__bold"),
            Some(svgs.join("tmpl__bold.svg")),
            "a staged variant must not be shadowed by its base"
        );
        assert_eq!(resolve_vector_svg("absent__bold"), None);
        // SAFETY: single test owning the env.
        unsafe { std::env::remove_var("DAY_VECTOR_SVG_ROOT") };

        // SAFETY: single test owning the env.
        unsafe {
            std::env::remove_var("DAY_ASSET_ROOT");
            std::env::remove_var("DAY_IMAGE_ROOT");
        }
        std::fs::remove_dir_all(&dir).ok();
    }

    #[test]
    fn from_vec_view_is_stable() {
        let r = Resource::from_vec(vec![1, 2, 3, 4]);
        assert_eq!(r.as_slice(), &[1, 2, 3, 4]);
        assert_eq!(r.to_vec(), vec![1, 2, 3, 4]);
        let mut b = [0u8; 2];
        assert_eq!(r.read_at(2, &mut b), 2);
        assert_eq!(b, [3, 4]);
    }
}