/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use std::path::PathBuf;
use std::sync::RwLock;

static RES: RwLock<Option<Box<dyn ResourceReaderMethods + Sync + Send>>> = RwLock::new(None);

#[cfg(feature = "baked-default-resources")]
static INIT_TEST_RESOURCES: std::sync::Once = std::sync::Once::new();

#[cfg(all(feature = "baked-default-resources", servo_production))]
const _: () = assert!(
    false,
    "baked-default-resources should not be used in production"
);

/// The Embedder should initialize the ResourceReader early.
pub fn set(reader: Box<dyn ResourceReaderMethods + Sync + Send>) {
    *RES.write().unwrap() = Some(reader);
}

#[cfg(not(feature = "baked-default-resources"))]
pub fn read_bytes(res: Resource) -> Vec<u8> {
    if let Some(reader) = RES.read().unwrap().as_ref() {
        reader.read(res)
    } else {
        log::error!("Resource reader not set.");
        vec![]
    }
}

#[cfg(feature = "baked-default-resources")]
pub fn read_bytes(res: Resource) -> Vec<u8> {
    INIT_TEST_RESOURCES.call_once(|| {
        let mut reader = RES.write().unwrap();
        if reader.is_none() {
            *reader = Some(resources_for_tests())
        }
    });
    RES.read()
        .unwrap()
        .as_ref()
        .expect("Resource reader not set.")
        .read(res)
}

pub fn read_string(res: Resource) -> String {
    String::from_utf8(read_bytes(res)).unwrap()
}

pub fn sandbox_access_files() -> Vec<PathBuf> {
    RES.read()
        .unwrap()
        .as_ref()
        .map(|reader| reader.sandbox_access_files())
        .unwrap_or_default()
}

pub fn sandbox_access_files_dirs() -> Vec<PathBuf> {
    RES.read()
        .unwrap()
        .as_ref()
        .map(|reader| reader.sandbox_access_files_dirs())
        .unwrap_or_default()
}

pub enum Resource {
    /// A list of GATT services that are blocked from being used by web bluetooth.
    /// The format of the file is a list of UUIDs, one per line, with an optional second word to specify the
    /// type of blocklist.
    /// It can be empty but then all GATT services will be allowed.
    BluetoothBlocklist,
    /// A list of domain names that are considered public suffixes, typically obtained from <https://publicsuffix.org/list/>.
    /// The Public Suffix List is a cross-vendor initiative to provide an accurate list of domain name suffixes
    /// that are under the control of a registry. This is used to prevent cookies from being set for top-level
    /// domains that are not controlled by the same entity as the website.
    /// It can be empty but all domain names will be considered not public suffixes.
    DomainList,
    /// A preloaded list of HTTP Strict Transport Security. It can be an empty list and
    /// `HstsList::default()` will be called.
    HstsPreloadList,
    /// A HTML page to display when `net_traits::NetworkError::SslValidation` network error is
    /// reported.
    /// The page contains placeholder `${reason}` for the error code and `${bytes}` for the certificate bytes,
    /// and also `${secret}` for the privileged secret.
    /// It can be empty but then nothing will be displayed when a certificate error occurs.
    BadCertHTML,
    /// A HTML page to display when any network error occurs that is not related to SSL validation.
    /// The message can contain a placeholder `${reason}` for the error code.
    /// It can be empty but then nothing will be displayed when an internal error occurs.
    NetErrorHTML,
    /// A placeholder image to display if we couldn't get the requested image.
    ///
    /// ## Panic
    ///
    /// If the resource is not provided, servo will fallback to a baked in default (See resources/rippy.png).
    /// However, if the image is provided but invalid, Servo will crash.
    RippyPNG,
    /// A placeholder HTML page to display when the code responsible for rendering a page panics and the original
    /// page can no longer be displayed.
    /// The message can contain a placeholder `${details}` for the error details.
    /// It can be empty but then nothing will be displayed when a crash occurs.
    CrashHTML,
    /// A HTML page to display when a directory listing is requested.
    /// The page contains a js function `setData` that will then be used to build the list of directory.
    /// It can be empty but then nothing will be displayed when a directory listing is requested.
    DirectoryListingHTML,
    /// A HTML page that is used for the about:memory url.
    AboutMemoryHTML,
}

impl Resource {
    pub fn filename(&self) -> &'static str {
        match self {
            Resource::BluetoothBlocklist => "gatt_blocklist.txt",
            Resource::DomainList => "public_domains.txt",
            Resource::HstsPreloadList => "hsts_preload.fstmap",
            Resource::BadCertHTML => "badcert.html",
            Resource::NetErrorHTML => "neterror.html",
            Resource::RippyPNG => "rippy.png",
            Resource::CrashHTML => "crash.html",
            Resource::DirectoryListingHTML => "directory-listing.html",
            Resource::AboutMemoryHTML => "about-memory.html",
        }
    }
}

pub trait ResourceReaderMethods {
    fn read(&self, res: Resource) -> Vec<u8>;
    fn sandbox_access_files(&self) -> Vec<PathBuf>;
    fn sandbox_access_files_dirs(&self) -> Vec<PathBuf>;
}

/// Provides baked in resources for tests.
///
/// Embedder builds (e.g. servoshell) should use [`set`] and ship the resources themselves.
#[cfg(feature = "baked-default-resources")]
fn resources_for_tests() -> Box<dyn ResourceReaderMethods + Sync + Send> {
    struct ResourceReader;
    impl ResourceReaderMethods for ResourceReader {
        fn sandbox_access_files(&self) -> Vec<PathBuf> {
            vec![]
        }
        fn sandbox_access_files_dirs(&self) -> Vec<PathBuf> {
            vec![]
        }
        fn read(&self, file: Resource) -> Vec<u8> {
            match file {
                Resource::BluetoothBlocklist => {
                    &include_bytes!("../../../resources/gatt_blocklist.txt")[..]
                },
                Resource::DomainList => {
                    &include_bytes!("../../../resources/public_domains.txt")[..]
                },
                Resource::HstsPreloadList => {
                    &include_bytes!("../../../resources/hsts_preload.fstmap")[..]
                },
                Resource::BadCertHTML => &include_bytes!("../../../resources/badcert.html")[..],
                Resource::NetErrorHTML => &include_bytes!("../../../resources/neterror.html")[..],
                Resource::RippyPNG => &include_bytes!("../../../resources/rippy.png")[..],
                Resource::CrashHTML => &include_bytes!("../../../resources/crash.html")[..],
                Resource::DirectoryListingHTML => {
                    &include_bytes!("../../../resources/directory-listing.html")[..]
                },
                Resource::AboutMemoryHTML => {
                    &include_bytes!("../../../resources/about-memory.html")[..]
                },
            }
            .to_owned()
        }
    }
    Box::new(ResourceReader)
}