// Copyright 2022 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use {
    crate::{
        component_instance::{ComponentInstanceInterface, ExtendedInstanceInterface},
        error::ComponentInstanceError,
    },
    anyhow::Error,
    clonable_error::ClonableError,
    fidl_fuchsia_component_resolution as fresolution, fidl_fuchsia_io as fio,
    fuchsia_zircon_status as zx,
    lazy_static::lazy_static,
    std::sync::Arc,
    thiserror::Error,
    url::Url,
    version_history::AbiRevision,
};

/// The prefix for relative URLs internally represented as url::Url.
const RELATIVE_URL_PREFIX: &str = "relative:///";
lazy_static! {
    /// A default base URL from which to parse relative component URL
    /// components.
    static ref RELATIVE_URL_BASE: Url = Url::parse(RELATIVE_URL_PREFIX).unwrap();
}

/// The response returned from a Resolver. This struct is derived from the FIDL
/// [`fuchsia.component.resolution.Component`][fidl_fuchsia_component_resolution::Component]
/// table, except that the opaque binary ComponentDecl has been deserialized and validated.
#[derive(Debug)]
pub struct ResolvedComponent {
    /// The url used to resolve this component.
    pub resolved_url: String,
    /// The package context, from the component resolution context returned by
    /// the resolver.
    pub context_to_resolve_children: Option<ComponentResolutionContext>,
    pub decl: cm_rust::ComponentDecl,
    pub package: Option<ResolvedPackage>,
    pub config_values: Option<cm_rust::ConfigValuesData>,
    pub abi_revision: Option<AbiRevision>,
}

/// The response returned from a Resolver. This struct is derived from the FIDL
/// [`fuchsia.component.resolution.Package`][fidl_fuchsia_component_resolution::Package]
/// table.
#[derive(Debug)]
pub struct ResolvedPackage {
    /// The package url.
    pub url: String,
    /// The package directory client proxy.
    pub directory: fidl::endpoints::ClientEnd<fio::DirectoryMarker>,
}

impl TryFrom<fresolution::Package> for ResolvedPackage {
    type Error = ResolverError;

    fn try_from(package: fresolution::Package) -> Result<Self, Self::Error> {
        Ok(ResolvedPackage {
            url: package.url.ok_or(ResolverError::PackageUrlMissing)?,
            directory: package.directory.ok_or(ResolverError::PackageDirectoryMissing)?,
        })
    }
}

/// Convenience wrapper type for the autogenerated FIDL
/// `fuchsia.component.resolution.Context`.
#[derive(Debug, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
pub struct ComponentResolutionContext {
    pub bytes: Vec<u8>,
}

impl ComponentResolutionContext {
    pub fn new(bytes: Vec<u8>) -> Self {
        ComponentResolutionContext { bytes }
    }
}

impl From<fresolution::Context> for ComponentResolutionContext {
    fn from(context: fresolution::Context) -> Self {
        ComponentResolutionContext { bytes: context.bytes }
    }
}

impl From<&fresolution::Context> for ComponentResolutionContext {
    fn from(context: &fresolution::Context) -> ComponentResolutionContext {
        ComponentResolutionContext { bytes: context.bytes.clone() }
    }
}

impl From<ComponentResolutionContext> for fresolution::Context {
    fn from(context: ComponentResolutionContext) -> Self {
        Self { bytes: context.bytes }
    }
}

impl From<&ComponentResolutionContext> for fresolution::Context {
    fn from(context: &ComponentResolutionContext) -> fresolution::Context {
        Self { bytes: context.bytes.clone() }
    }
}

impl<'a> From<&'a ComponentResolutionContext> for &'a [u8] {
    fn from(context: &'a ComponentResolutionContext) -> &'a [u8] {
        &context.bytes
    }
}

/// Provides the `ComponentAddress` and context for resolving a child or
/// descendent component.
#[derive(Debug, Clone, PartialEq, Eq)]
struct ResolvedAncestorComponent {
    /// The component address, needed for relative path URLs (to get the
    /// scheme used to find the required `Resolver`), or for relative resource
    /// URLs (which will clone the parent's address, but replace the resource).
    pub address: ComponentAddress,
    /// The component's resolution_context, required for resolving descendents
    /// using a relative path component URLs.
    pub context_to_resolve_children: Option<ComponentResolutionContext>,
}

impl ResolvedAncestorComponent {
    /// Creates a `ResolvedAncestorComponent` from one of its child components.
    pub async fn direct_parent_of<C: ComponentInstanceInterface>(
        component: &Arc<C>,
    ) -> Result<Self, ResolverError> {
        let parent_component = get_parent(component).await?;
        let resolved_parent = parent_component.lock_resolved_state().await?;
        Ok(Self {
            address: resolved_parent.address(),
            context_to_resolve_children: resolved_parent.context_to_resolve_children(),
        })
    }

    /// Creates a `ResolvedAncestorComponent` from one of its child components.
    pub async fn first_packaged_ancestor_of<C: ComponentInstanceInterface>(
        component: &Arc<C>,
    ) -> Result<Self, ResolverError> {
        let mut parent_component = get_parent(component).await?;
        loop {
            // Loop until the parent has a valid context_to_resolve_children,
            // or an error getting the next parent, or its resolved state.
            {
                let resolved_parent = parent_component.lock_resolved_state().await?;
                let address = resolved_parent.address();
                // TODO(https://fxbug.dev/42053123): change this test to something more
                // explicit, that is, return the parent's address and context if
                // the component address is a packaged component (determined in
                // some way).
                //
                // The issue being addressed here is, when resolving a relative
                // subpackaged component URL, component manager MUST resolve the
                // component using a "resolution context" _AND_ the resolver
                // that provided that context. Typically these are provided by
                // the parent component, but in the case of a RealmBuilder child
                // component, its parent is the built "realm" (which was
                // resolved by the realm_builder_resolver, using URL scheme
                // "realm-builder://"). The child component's URL is supposed to
                // be relative to the test component (the parent of the realm),
                // which was probably resolved by the full-resolver (scheme
                // "fuchsia-pkg://"). Knowing this expected topology, we can
                // skip "realm-builder" components when searching for the
                // required ancestor's URL scheme (to get the right resolver)
                // and context. This is a brittle workaround that will be
                // replaced.
                //
                // Some alternatives are under discussion, but the leading
                // candidate, for now, is to allow a resolver to return a flag
                // (with the resolved Component; perhaps `is_packaged()`) to
                // indicate that descendents should (if true) use this component
                // to get scheme and context for resolving relative path URLs
                // (for example, subpackages). If false, get the parent's parent
                // and so on.
                if address.scheme() != "realm-builder" {
                    return Ok(Self {
                        address,
                        context_to_resolve_children: resolved_parent.context_to_resolve_children(),
                    });
                }
            }
            parent_component = get_parent(&parent_component).await?;
        }
    }
}

async fn get_parent<C: ComponentInstanceInterface>(
    component: &Arc<C>,
) -> Result<Arc<C>, ResolverError> {
    if let ExtendedInstanceInterface::Component(parent_component) =
        component.try_get_parent().map_err(|err| {
            ResolverError::no_parent_context(anyhow::format_err!(
                "Component {} ({}) has no parent for context: {:?}.",
                component.moniker(),
                component.url(),
                err,
            ))
        })?
    {
        Ok(parent_component.clone())
    } else {
        Err(ResolverError::no_parent_context(anyhow::format_err!(
            "Component {} ({}) has no parent for context.",
            component.moniker(),
            component.url(),
        )))
    }
}

/// Indicates the kind of `ComponentAddress`, and holds `ComponentAddress`
/// properties specific to its kind. Note that there is no kind for a relative
/// resource component URL (a URL that only contains a resource fragment, such
/// as `#meta/comp.cm`) because `ComponentAddress::from()` will translate a
/// resource fragment component URL into one of the fully-resolvable
/// `ComponentAddress`s.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ComponentAddress {
    /// A fully-qualified component URL.
    Absolute { url: Url },

    /// A relative Component URL, starting with the package path; for example a
    /// subpackage relative URL such as "needed_package#meta/dep_component.cm".
    RelativePath {
        /// This is the scheme of the ancestor component's absolute URL, used to identify the
        /// `Resolver` in a `ResolverRegistry`.
        scheme: String,

        /// The relative URL, represented as a `url::Url` with the `relative:///` base prefix.
        /// `url::Url` cannot represent relative urls directly.
        url: Url,

        /// An opaque value (from the perspective of component resolution)
        /// required by the resolver when resolving a relative package path.
        /// For a given child component, this property is populated from a
        /// parent component's `resolution_context`, as returned by the parent
        /// component's resolver.
        context: ComponentResolutionContext,
    },
}

impl ComponentAddress {
    /// Creates a new `ComponentAddress` of the `Absolute` kind.
    fn new_absolute(url: Url) -> Self {
        Self::Absolute { url }
    }

    /// Creates a new `ComponentAddress` of the `RelativePath` kind.
    fn new_relative_path(
        path: &str,
        some_resource: Option<&str>,
        scheme: &str,
        context: ComponentResolutionContext,
    ) -> Result<Self, ResolverError> {
        let mut url = RELATIVE_URL_BASE.clone();
        url.set_path(path);
        url.set_fragment(some_resource);
        Self::check_relative_url(&url)?;
        Ok(Self::RelativePath { url, context, scheme: scheme.into() })
    }

    /// Parse the given absolute `component_url` and create a `ComponentAddress`
    /// with kind `Absolute`.
    pub fn from_absolute_url(component_url: &cm_types::Url) -> Result<Self, ResolverError> {
        match Url::parse(component_url.as_str()) {
            Ok(url) => Ok(Self::new_absolute(url)),
            Err(url::ParseError::RelativeUrlWithoutBase) => {
                Err(ResolverError::RelativeUrlNotExpected(component_url.to_string()))
            }
            Err(err) => Err(ResolverError::malformed_url(err)),
        }
    }

    /// Assumes the given string is a relative URL, and converts this string into
    /// a `url::Url` by attaching a known, internal absolute URL prefix.
    fn parse_relative_url(component_url: &cm_types::Url) -> Result<Url, ResolverError> {
        let component_url = component_url.as_str();
        match Url::parse(component_url) {
            Ok(_) => Err(ResolverError::malformed_url(anyhow::format_err!(
                "Error parsing a relative URL given absolute URL '{}'.",
                component_url,
            ))),
            Err(url::ParseError::RelativeUrlWithoutBase) => {
                RELATIVE_URL_BASE.join(component_url).map_err(|err| {
                    ResolverError::malformed_url(anyhow::format_err!(
                        "Error parsing a relative component URL '{}': {:?}.",
                        component_url,
                        err
                    ))
                })
            }
            Err(err) => Err(ResolverError::malformed_url(anyhow::format_err!(
                "Unexpected error while parsing a component URL '{}': {:?}.",
                component_url,
                err,
            ))),
        }
    }

    fn check_relative_url(url: &Url) -> Result<(), ResolverError> {
        let truncated_url = url.as_str().strip_prefix(RELATIVE_URL_PREFIX).ok_or_else(|| {
            ResolverError::malformed_url(anyhow::format_err!(
                "Could not strip relative prefix from url. This is a bug. {}",
                url
            ))
        })?;
        let relative_url = RELATIVE_URL_BASE.make_relative(&url).ok_or_else(|| {
            ResolverError::malformed_url(anyhow::format_err!(
                "Could not make relative url. This is a bug. {}",
                url
            ))
        })?;
        if truncated_url != relative_url {
            return Err(ResolverError::malformed_url(anyhow::format_err!(
                "Relative url generated from url::Url did not match expectations. \
                This is a bug. {}",
                url
            )));
        }
        Ok(())
    }

    /// For `Url`s constructed from `parse_relative_url()`, the `path()` is expected
    /// to include a slash prefix, but a String representation of a relative path
    /// URL should not include the slash prefix. This convenience API assumes the
    /// given `Url` is a relative URL, and strips the slash prefix, if present.
    fn relative_path(relative_url: &Url) -> &str {
        let path = relative_url.path();
        path.strip_prefix('/').unwrap_or(path)
    }

    /// Parse the given `component_url` to determine if it is an absolute URL,
    /// a relative subpackage URL, or a relative resource URL, and return the
    /// corresponding `ComponentAddress` enum variant and value. If the URL is
    /// relative, use the component instance to get the required resolution
    /// context from the component's parent.
    pub async fn from<C: ComponentInstanceInterface>(
        component_url: &cm_types::Url,
        component: &Arc<C>,
    ) -> Result<Self, ResolverError> {
        let result = Self::from_absolute_url(component_url);
        if !matches!(result, Err(ResolverError::RelativeUrlNotExpected(_))) {
            return result;
        }
        let relative_url = Self::parse_relative_url(component_url)?;
        let relative_path = Self::relative_path(&relative_url);
        if relative_url.fragment().is_none() && relative_path.is_empty() {
            return Err(ResolverError::malformed_url(anyhow::format_err!("{}", component_url)));
        }
        if relative_url.query().is_some() {
            return Err(ResolverError::malformed_url(anyhow::format_err!(
                "Query strings are not allowed in relative component URLs: {}",
                component_url
            )));
        }
        if relative_path.is_empty() {
            // The `component_url` had only a fragment, so the new address will
            // be the same as its parent (for example, the same package), except
            // for its resource.
            let resolved_parent = ResolvedAncestorComponent::direct_parent_of(component).await?;
            resolved_parent.address.clone_with_new_resource(relative_url.fragment())
        } else {
            // The `component_url` starts with a relative path (for example, a
            // subpackage name). Create a `RelativePath` address, and resolve it
            // using the `context_to_resolve_children`, from this component's
            // parent, or the first ancestor that is from a "package". (Note
            // that Realm Builder realms are synthesized, and not from a
            // package. A test component using Realm Builder will build a realm
            // and may add child components using subpackage references. Those
            // child components should get resolved using the context of the
            // test package, not the intermediate realm created via
            // RealmBuilder.)
            let resolved_ancestor =
                ResolvedAncestorComponent::first_packaged_ancestor_of(component).await?;
            let scheme = resolved_ancestor.address.scheme();
            let context = resolved_ancestor.context_to_resolve_children.clone().ok_or_else(|| {
                    ResolverError::RelativeUrlMissingContext(format!(
                        "Relative path component URL '{}' cannot be resolved because its ancestor did not provide a resolution context. The ancestor's component address is {:?}.",
                         component_url, resolved_ancestor.address
                    ))
                })?;
            Self::new_relative_path(relative_path, relative_url.fragment(), scheme, context)
        }
    }

    /// Creates a new `ComponentAddress` from `self` by replacing only the
    /// component URL resource.
    pub fn clone_with_new_resource(
        &self,
        some_resource: Option<&str>,
    ) -> Result<Self, ResolverError> {
        let mut url = match &self {
            Self::Absolute { url } => url.clone(),
            Self::RelativePath { url, .. } => url.clone(),
        };
        url.set_fragment(some_resource);
        match &self {
            Self::Absolute { .. } => Ok(Self::Absolute { url }),
            Self::RelativePath { context, scheme, .. } => {
                Self::check_relative_url(&url)?;
                Ok(Self::RelativePath { url, context: context.clone(), scheme: scheme.clone() })
            }
        }
    }

    /// True if the address is `Absolute`.
    pub fn is_absolute(&self) -> bool {
        matches!(self, Self::Absolute { .. })
    }

    /// True if the address is `RelativePath`.
    pub fn is_relative_path(&self) -> bool {
        matches!(self, Self::RelativePath { .. })
    }

    /// Returns the `ComponentResolutionContext` value required to resolve for a
    /// `RelativePath` component URL.
    ///
    /// Panics if called for an `Absolute` component address.
    pub fn context(&self) -> &ComponentResolutionContext {
        if let Self::RelativePath { context, .. } = self {
            &context
        } else {
            panic!("context() is only valid for `ComponentAddressKind::RelativePath");
        }
    }

    /// Returns the URL scheme either provided for an `Absolute` URL or derived
    /// from the component's parent. The scheme is used to look up a registered
    /// resolver, when resolving the component.
    pub fn scheme(&self) -> &str {
        match self {
            Self::Absolute { url } => url.scheme(),
            Self::RelativePath { scheme, .. } => &scheme,
        }
    }

    /// Returns the URL path.
    pub fn path(&self) -> &str {
        match self {
            Self::Absolute { url } => url.path(),
            Self::RelativePath { url, .. } => Self::relative_path(&url),
        }
    }

    /// Returns the optional query value for an `Absolute` component URL.
    /// Always returns `None` for `Relative` component URLs.
    pub fn query(&self) -> Option<&str> {
        match self {
            Self::Absolute { url } => url.query(),
            Self::RelativePath { .. } => None,
        }
    }

    /// Returns the optional component resource, from the URL fragment.
    pub fn resource(&self) -> Option<&str> {
        match self {
            Self::Absolute { url } => url.fragment(),
            Self::RelativePath { url, .. } => url.fragment(),
        }
    }

    /// Returns the resolver-ready URL string and, if it is a `RelativePath`,
    /// `Some(context)`, or `None` for an `Absolute` address.
    pub fn url(&self) -> &str {
        match self {
            Self::Absolute { url } => url.as_str(),
            Self::RelativePath { url, .. } => &url.as_str()[RELATIVE_URL_PREFIX.len()..],
        }
    }

    /// Returns the `url()` and `Some(context)` for resolving the URL,
    /// if the kind is `RelativePath` (or `None` if `Absolute`).
    pub fn to_url_and_context(&self) -> (&str, Option<&ComponentResolutionContext>) {
        match self {
            Self::Absolute { .. } => (self.url(), None),
            Self::RelativePath { context, .. } => (self.url(), Some(context)),
        }
    }
}

/// Errors produced by built-in `Resolver`s and `resolving` APIs.
#[derive(Debug, Error, Clone)]
pub enum ResolverError {
    #[error("an unexpected error occurred: {0}")]
    Internal(#[source] ClonableError),
    #[error("an IO error occurred: {0}")]
    Io(#[source] ClonableError),
    #[error("component manifest not found: {0}")]
    ManifestNotFound(#[source] ClonableError),
    #[error("package not found: {0}")]
    PackageNotFound(#[source] ClonableError),
    #[error("component manifest invalid: {0}")]
    ManifestInvalid(#[source] ClonableError),
    #[error("config values file invalid: {0}")]
    ConfigValuesInvalid(#[source] ClonableError),
    #[error("abi revision not found")]
    AbiRevisionNotFound,
    #[error("abi revision invalid: {0}")]
    AbiRevisionInvalid(#[source] ClonableError),
    #[error("failed to read config values: {0}")]
    ConfigValuesIo(zx::Status),
    #[error("scheme not registered")]
    SchemeNotRegistered,
    #[error("malformed url: {0}")]
    MalformedUrl(#[source] ClonableError),
    #[error("relative url requires a parent component with resolution context: {0}")]
    NoParentContext(#[source] ClonableError),
    #[error("package URL missing")]
    PackageUrlMissing,
    #[error("package directory handle missing")]
    PackageDirectoryMissing,
    #[error("a relative URL was not expected: {0}")]
    RelativeUrlNotExpected(String),
    #[error("failed to route resolver capability: {0}")]
    RoutingError(#[source] ClonableError),
    #[error("a context is required to resolve relative url: {0}")]
    RelativeUrlMissingContext(String),
    #[error("this component resolver does not resolve relative path component URLs: {0}")]
    UnexpectedRelativePath(String),
    #[error("the remote resolver returned invalid data")]
    RemoteInvalidData,
    #[error("an error occurred sending a FIDL request to the remote resolver: {0}")]
    FidlError(#[source] ClonableError),
}

impl ResolverError {
    pub fn as_zx_status(&self) -> zx::Status {
        match self {
            ResolverError::PackageNotFound(_)
            | ResolverError::ManifestNotFound(_)
            | ResolverError::ManifestInvalid(_)
            | ResolverError::ConfigValuesInvalid(_)
            | ResolverError::Io(_)
            | ResolverError::ConfigValuesIo(_)
            | ResolverError::AbiRevisionNotFound
            | ResolverError::AbiRevisionInvalid(_)
            | ResolverError::SchemeNotRegistered
            | ResolverError::MalformedUrl(_)
            | ResolverError::NoParentContext(_)
            | ResolverError::RelativeUrlMissingContext(_)
            | ResolverError::RemoteInvalidData
            | ResolverError::PackageUrlMissing
            | ResolverError::PackageDirectoryMissing
            | ResolverError::UnexpectedRelativePath(_) => zx::Status::NOT_FOUND,

            ResolverError::Internal(_)
            | ResolverError::RelativeUrlNotExpected(_)
            | ResolverError::RoutingError(_)
            | ResolverError::FidlError(_) => zx::Status::INTERNAL,
        }
    }

    pub fn internal(err: impl Into<Error>) -> Self {
        Self::Internal(err.into().into())
    }

    pub fn io(err: impl Into<Error>) -> Self {
        Self::Io(err.into().into())
    }

    pub fn manifest_not_found(err: impl Into<Error>) -> Self {
        Self::ManifestNotFound(err.into().into())
    }

    pub fn package_not_found(err: impl Into<Error>) -> Self {
        Self::PackageNotFound(err.into().into())
    }

    pub fn manifest_invalid(err: impl Into<Error>) -> Self {
        Self::ManifestInvalid(err.into().into())
    }

    pub fn config_values_invalid(err: impl Into<Error>) -> Self {
        Self::ConfigValuesInvalid(err.into().into())
    }

    pub fn abi_revision_invalid(err: impl Into<Error>) -> Self {
        Self::AbiRevisionInvalid(err.into().into())
    }

    pub fn malformed_url(err: impl Into<Error>) -> Self {
        Self::MalformedUrl(err.into().into())
    }

    pub fn no_parent_context(err: impl Into<Error>) -> Self {
        Self::NoParentContext(err.into().into())
    }

    pub fn routing_error(err: impl Into<Error>) -> Self {
        Self::RoutingError(err.into().into())
    }

    pub fn fidl_error(err: impl Into<Error>) -> Self {
        Self::FidlError(err.into().into())
    }
}

impl From<fresolution::ResolverError> for ResolverError {
    fn from(err: fresolution::ResolverError) -> ResolverError {
        match err {
            fresolution::ResolverError::Internal => ResolverError::internal(RemoteError(err)),
            fresolution::ResolverError::Io => ResolverError::io(RemoteError(err)),
            fresolution::ResolverError::PackageNotFound
            | fresolution::ResolverError::NoSpace
            | fresolution::ResolverError::ResourceUnavailable
            | fresolution::ResolverError::NotSupported => {
                ResolverError::package_not_found(RemoteError(err))
            }
            fresolution::ResolverError::ManifestNotFound => {
                ResolverError::manifest_not_found(RemoteError(err))
            }
            fresolution::ResolverError::InvalidArgs => {
                ResolverError::malformed_url(RemoteError(err))
            }
            fresolution::ResolverError::InvalidManifest => {
                ResolverError::ManifestInvalid(anyhow::Error::from(RemoteError(err)).into())
            }
            fresolution::ResolverError::ConfigValuesNotFound => {
                ResolverError::ConfigValuesIo(zx::Status::NOT_FOUND)
            }
            fresolution::ResolverError::AbiRevisionNotFound => ResolverError::AbiRevisionNotFound,
            fresolution::ResolverError::InvalidAbiRevision => {
                ResolverError::abi_revision_invalid(RemoteError(err))
            }
        }
    }
}

impl From<ComponentInstanceError> for ResolverError {
    fn from(err: ComponentInstanceError) -> ResolverError {
        use ComponentInstanceError::*;
        match &err {
            ComponentManagerInstanceUnavailable {}
            | InstanceNotFound { .. }
            | ResolveFailed { .. } => {
                ResolverError::Internal(ClonableError::from(anyhow::format_err!("{:?}", err)))
            }
            NoAbsoluteUrl { .. } => ResolverError::NoParentContext(ClonableError::from(
                anyhow::format_err!("{:?}", err),
            )),
            MalformedUrl { .. } => {
                ResolverError::MalformedUrl(ClonableError::from(anyhow::format_err!("{:?}", err)))
            }
        }
    }
}

#[derive(Error, Clone, Debug)]
#[error("remote resolver responded with {0:?}")]
struct RemoteError(fresolution::ResolverError);

#[cfg(test)]
mod tests {
    use {super::*, assert_matches::assert_matches, fidl::endpoints::create_endpoints};

    fn from_absolute_url(url: &str) -> ComponentAddress {
        ComponentAddress::from_absolute_url(&url.parse().unwrap()).unwrap()
    }

    fn parse_relative_url(url: &str) -> Url {
        ComponentAddress::parse_relative_url(&url.parse().unwrap()).unwrap()
    }

    #[test]
    fn test_resolved_package() {
        let url = "some_url".to_string();
        let (dir_client, _) = create_endpoints::<fio::DirectoryMarker>();
        let fidl_package = fresolution::Package {
            url: Some(url.clone()),
            directory: Some(dir_client),
            ..Default::default()
        };
        let resolved_package = ResolvedPackage::try_from(fidl_package).unwrap();
        assert_eq!(resolved_package.url, url);
    }

    #[test]
    fn test_component_address() {
        let address = from_absolute_url("some-scheme://fuchsia.com/package#meta/comp.cm");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "some-scheme");
        assert_eq!(address.path(), "/package");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), Some("meta/comp.cm"));
        assert_eq!(address.url(), "some-scheme://fuchsia.com/package#meta/comp.cm");
        assert_matches!(
            address.to_url_and_context(),
            ("some-scheme://fuchsia.com/package#meta/comp.cm", None)
        );

        let abs_address = ComponentAddress::new_absolute(
            Url::parse("some-scheme://fuchsia.com/package#meta/comp.cm").unwrap(),
        );
        assert_eq!(abs_address, address);

        assert_eq!(abs_address, address);
        assert!(abs_address.is_absolute());
        assert_eq!(abs_address.scheme(), "some-scheme");
        assert_eq!(abs_address.path(), "/package");
        assert_eq!(abs_address.query(), None);
        assert_eq!(abs_address.resource(), Some("meta/comp.cm"));
        assert_eq!(abs_address.url(), "some-scheme://fuchsia.com/package#meta/comp.cm");
        assert_matches!(
            abs_address.to_url_and_context(),
            ("some-scheme://fuchsia.com/package#meta/comp.cm", None)
        );

        let cloned_address = abs_address.clone();
        assert_eq!(abs_address, cloned_address);

        let address2 = abs_address.clone_with_new_resource(Some("meta/other_comp.cm")).unwrap();
        assert_ne!(address2, abs_address);
        assert!(address2.is_absolute());
        assert_eq!(address2.resource(), Some("meta/other_comp.cm"));
        assert_eq!(address2.scheme(), "some-scheme");
        assert_eq!(address2.path(), "/package");
        assert_eq!(address2.query(), None);

        let rel_address = ComponentAddress::new_relative_path(
            "subpackage",
            Some("meta/subcomp.cm"),
            "some-scheme",
            ComponentResolutionContext::new(vec![b'4', b'5', b'6']),
        )
        .unwrap();
        if let ComponentAddress::RelativePath { ref context, .. } = rel_address {
            assert_eq!(&context.bytes, &vec![b'4', b'5', b'6']);
        }
        assert!(rel_address.is_relative_path());
        assert_eq!(rel_address.path(), "subpackage");
        assert_eq!(rel_address.query(), None);
        assert_eq!(rel_address.resource(), Some("meta/subcomp.cm"));
        assert_eq!(&rel_address.context().bytes, &vec![b'4', b'5', b'6']);
        assert_eq!(rel_address.url(), "subpackage#meta/subcomp.cm");
        assert_eq!(
            rel_address.to_url_and_context(),
            (
                "subpackage#meta/subcomp.cm",
                Some(&ComponentResolutionContext::new(vec![b'4', b'5', b'6']))
            )
        );

        let rel_address2 =
            rel_address.clone_with_new_resource(Some("meta/other_subcomp.cm")).unwrap();
        assert_ne!(rel_address2, rel_address);
        assert!(rel_address2.is_relative_path());
        assert_eq!(rel_address2.path(), "subpackage");
        assert_eq!(rel_address2.query(), None);
        assert_eq!(rel_address2.resource(), Some("meta/other_subcomp.cm"));
        assert_eq!(&rel_address2.context().bytes, &vec![b'4', b'5', b'6']);
        assert_eq!(rel_address2.url(), "subpackage#meta/other_subcomp.cm");
        assert_eq!(
            rel_address2.to_url_and_context(),
            (
                "subpackage#meta/other_subcomp.cm",
                Some(&ComponentResolutionContext::new(vec![b'4', b'5', b'6']))
            )
        );

        let address = from_absolute_url("base://b");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "base");
        assert_eq!(address.path(), "");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), None);
        assert_eq!(address.url(), "base://b");
        assert_matches!(address.to_url_and_context(), ("base://b", None));

        let address = from_absolute_url("fuchsia-boot:///#meta/root.cm");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "fuchsia-boot");
        assert_eq!(address.path(), "/");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), Some("meta/root.cm"));
        assert_eq!(address.url(), "fuchsia-boot:///#meta/root.cm");
        assert_matches!(address.to_url_and_context(), ("fuchsia-boot:///#meta/root.cm", None));

        let address = from_absolute_url("custom-resolver:my:special:path#meta/root.cm");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "custom-resolver");
        assert_eq!(address.path(), "my:special:path");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), Some("meta/root.cm"));
        assert_eq!(address.url(), "custom-resolver:my:special:path#meta/root.cm");
        assert_matches!(
            address.to_url_and_context(),
            ("custom-resolver:my:special:path#meta/root.cm", None)
        );

        let address = from_absolute_url("cast:00000000");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "cast");
        assert_eq!(address.path(), "00000000");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), None);
        assert_eq!(address.url(), "cast:00000000");
        assert_matches!(address.to_url_and_context(), ("cast:00000000", None));

        let address = from_absolute_url("cast:00000000#meta/root.cm");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "cast");
        assert_eq!(address.path(), "00000000");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), Some("meta/root.cm"));
        assert_eq!(address.url(), "cast:00000000#meta/root.cm");
        assert_matches!(address.to_url_and_context(), ("cast:00000000#meta/root.cm", None));

        let address =
            from_absolute_url("fuchsia-pkg://fuchsia.com/package?hash=cafe0123#meta/comp.cm");
        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "fuchsia-pkg");
        assert_eq!(address.path(), "/package");
        assert_eq!(address.resource(), Some("meta/comp.cm"));
        assert_eq!(address.query(), Some("hash=cafe0123"));
        assert_eq!(address.url(), "fuchsia-pkg://fuchsia.com/package?hash=cafe0123#meta/comp.cm");
        assert_matches!(
            address.to_url_and_context(),
            ("fuchsia-pkg://fuchsia.com/package?hash=cafe0123#meta/comp.cm", None)
        );
    }

    #[test]
    fn test_relative_path() {
        let url = Url::parse("relative:///package#fragment").unwrap();
        assert_eq!(url.path(), "/package");
        assert_eq!(ComponentAddress::relative_path(&url), "package");

        let url = Url::parse("cast:00000000#fragment").unwrap();
        assert_eq!(url.path(), "00000000");
        assert_eq!(ComponentAddress::relative_path(&url), "00000000");
    }

    #[test]
    fn test_parse_relative_url() {
        let relative_prefix_with_one_less_slash = Url::parse("relative://").unwrap();
        assert_eq!(relative_prefix_with_one_less_slash.scheme(), "relative");
        assert_eq!(relative_prefix_with_one_less_slash.host(), None);
        assert_eq!(relative_prefix_with_one_less_slash.path(), "");

        assert_eq!(RELATIVE_URL_BASE.scheme(), "relative");
        assert_eq!(RELATIVE_URL_BASE.host(), None);
        assert_eq!(RELATIVE_URL_BASE.path(), "/");

        let mut clone_relative_base = RELATIVE_URL_BASE.clone();
        assert_eq!(clone_relative_base.path(), "/");
        clone_relative_base.set_path("");
        assert_eq!(clone_relative_base.path(), "");

        let mut clone_relative_base = RELATIVE_URL_BASE.clone();
        assert_eq!(clone_relative_base.path(), "/");
        clone_relative_base.set_path("some_path_no_initial_slash");
        assert_eq!(clone_relative_base.path(), "/some_path_no_initial_slash");

        let clone_relative_base = RELATIVE_URL_BASE.clone();
        let joined = clone_relative_base.join("some_path_no_initial_slash").unwrap();
        assert_eq!(joined.path(), "/some_path_no_initial_slash");

        let clone_relative_base = relative_prefix_with_one_less_slash.clone();
        let joined = clone_relative_base.join("some_path_no_initial_slash").unwrap();
        // Same result as with three slashes
        assert_eq!(joined.path(), "/some_path_no_initial_slash");

        let relative_url = parse_relative_url("subpackage#meta/subcomp.cm");
        assert_eq!(relative_url.path(), "/subpackage");
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/subcomp.cm"));

        let relative_url = parse_relative_url("/subpackage#meta/subcomp.cm");
        assert_eq!(relative_url.path(), "/subpackage");
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/subcomp.cm"));

        let relative_url = parse_relative_url("//subpackage#meta/subcomp.cm");
        assert_eq!(relative_url.path(), "");
        assert_eq!(relative_url.host_str(), Some("subpackage"));
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/subcomp.cm"));

        let relative_url = parse_relative_url("///subpackage#meta/subcomp.cm");
        assert_eq!(relative_url.path(), "/subpackage");
        assert_eq!(relative_url.host_str(), None);
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/subcomp.cm"));

        let relative_url = parse_relative_url("fuchsia.com/subpackage#meta/subcomp.cm");
        assert_eq!(relative_url.path(), "/fuchsia.com/subpackage");
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/subcomp.cm"));

        let relative_url = parse_relative_url("//fuchsia.com/subpackage#meta/subcomp.cm");
        assert_eq!(relative_url.path(), "/subpackage");
        assert_eq!(relative_url.host_str(), Some("fuchsia.com"));
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/subcomp.cm"));

        assert_matches!(
            ComponentAddress::parse_relative_url(
                &"fuchsia-pkg://fuchsia.com/subpackage#meta/subcomp.cm".parse().unwrap()
            ),
            Err(ResolverError::MalformedUrl(..))
        );

        let relative_url = parse_relative_url("#meta/peercomp.cm");
        assert_eq!(relative_url.path(), "/");
        assert_eq!(relative_url.query(), None);
        assert_eq!(relative_url.fragment(), Some("meta/peercomp.cm"));

        let address = from_absolute_url("some-scheme://fuchsia.com/package#meta/comp.cm")
            .clone_with_new_resource(relative_url.fragment())
            .unwrap();

        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "some-scheme");
        assert_eq!(address.path(), "/package");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), Some("meta/peercomp.cm"));
        assert_eq!(address.url(), "some-scheme://fuchsia.com/package#meta/peercomp.cm");

        let address = from_absolute_url("cast:00000000")
            .clone_with_new_resource(relative_url.fragment())
            .unwrap();

        assert!(address.is_absolute());
        assert_eq!(address.scheme(), "cast");
        assert_eq!(address.path(), "00000000");
        assert_eq!(address.query(), None);
        assert_eq!(address.resource(), Some("meta/peercomp.cm"));
        assert_eq!(address.url(), "cast:00000000#meta/peercomp.cm");
    }
}