// 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/.

/*! Debian repository HTTP client.

This module provides functionality for interfacing with HTTP based Debian
repositories.
*/

use {
    crate::{
        error::{DebianError, Result},
        io::DataResolver,
        repository::{release::ReleaseFile, Compression, ReleaseReader, RepositoryRootReader},
    },
    async_trait::async_trait,
    futures::{stream::TryStreamExt, AsyncRead},
    reqwest::{Client, ClientBuilder, IntoUrl, StatusCode, Url},
    std::pin::Pin,
};

/// Default HTTP user agent string.
pub const USER_AGENT: &str =
    "debian-packaging Rust crate (https://crates.io/crates/debian-packaging)";

async fn fetch_url(
    client: &Client,
    root_url: &Url,
    path: &str,
) -> Result<Pin<Box<dyn AsyncRead + Send>>> {
    let request_url = root_url.join(path)?;

    let res = client.get(request_url.clone()).send().await.map_err(|e| {
        DebianError::RepositoryIoPath(
            path.to_string(),
            std::io::Error::new(
                std::io::ErrorKind::Other,
                format!("error sending HTTP request: {:?}", e),
            ),
        )
    })?;

    let res = res.error_for_status().map_err(|e| {
        if e.status() == Some(StatusCode::NOT_FOUND) {
            DebianError::RepositoryIoPath(
                path.to_string(),
                std::io::Error::new(
                    std::io::ErrorKind::NotFound,
                    format!("HTTP 404 for {}", request_url),
                ),
            )
        } else {
            DebianError::RepositoryIoPath(
                path.to_string(),
                std::io::Error::new(
                    std::io::ErrorKind::Other,
                    format!("bad HTTP status code: {:?}", e),
                ),
            )
        }
    })?;

    Ok(Box::pin(
        res.bytes_stream()
            .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, format!("{:?}", e)))
            .into_async_read(),
    ))
}

/// Client for a Debian repository served via HTTP.
///
/// Instances are bound to a base URL, which represents the base directory.
///
/// Distributions (typically) exist in a `dists/<distribution>` directory.
/// Distributions have an `InRelease` and/or `Release` file under it.
#[derive(Debug)]
pub struct HttpRepositoryClient {
    /// HTTP client to use.
    client: Client,

    /// Base URL for this Debian archive.
    ///
    /// Contains both distributions and the files pool.
    root_url: Url,
}

impl HttpRepositoryClient {
    /// Construct an instance bound to the specified URL.
    pub fn new(url: impl IntoUrl) -> Result<Self> {
        let builder = ClientBuilder::new().user_agent(USER_AGENT);

        Self::new_client(builder.build()?, url)
    }

    /// Construct an instance using the given [Client] and URL.
    ///
    /// The given URL should be the value that follows the
    /// `deb` line in apt sources files. e.g. for
    /// `deb https://deb.debian.org/debian stable main`, the value would be
    /// `https://deb.debian.org/debian`. The URL typically has a `dists/` directory
    /// underneath.
    pub fn new_client(client: Client, url: impl IntoUrl) -> Result<Self> {
        let mut root_url = url.into_url()?;

        // Trailing URLs are significant to the Url type when we .join(). So ensure
        // the URL has a trailing path.
        if !root_url.path().ends_with('/') {
            root_url.set_path(&format!("{}/", root_url.path()));
        }

        Ok(Self { client, root_url })
    }
}

#[async_trait]
impl DataResolver for HttpRepositoryClient {
    async fn get_path(&self, path: &str) -> Result<Pin<Box<dyn AsyncRead + Send>>> {
        fetch_url(&self.client, &self.root_url, path).await
    }
}

#[async_trait]
impl RepositoryRootReader for HttpRepositoryClient {
    fn url(&self) -> Result<Url> {
        Ok(self.root_url.clone())
    }

    async fn release_reader_with_distribution_path(
        &self,
        path: &str,
    ) -> Result<Box<dyn ReleaseReader>> {
        let distribution_path = path.trim_matches('/').to_string();
        let release_path = join_path(&distribution_path, "InRelease");
        let mut root_url = self.root_url.join(&distribution_path)?;

        // Trailing URLs are significant to the Url type when we .join(). So ensure
        // the URL has a trailing path.
        if !root_url.path().ends_with('/') {
            root_url.set_path(&format!("{}/", root_url.path()));
        }

        let release = self.fetch_inrelease(&release_path).await?;

        let fetch_compression = Compression::default_preferred_order()
            .next()
            .expect("iterator should not be empty");

        Ok(Box::new(HttpReleaseClient {
            client: self.client.clone(),
            root_url,
            relative_path: distribution_path,
            release,
            fetch_compression,
        }))
    }
}

fn join_path(a: &str, b: &str) -> String {
    format!("{}/{}", a.trim_matches('/'), b.trim_start_matches('/'))
}

/// Repository HTTP client bound to a parsed `Release` or `InRelease` file.
pub struct HttpReleaseClient {
    client: Client,
    root_url: Url,
    relative_path: String,
    release: ReleaseFile<'static>,
    fetch_compression: Compression,
}

#[async_trait]
impl DataResolver for HttpReleaseClient {
    async fn get_path(&self, path: &str) -> Result<Pin<Box<dyn AsyncRead + Send>>> {
        fetch_url(&self.client, &self.root_url, path).await
    }
}

#[async_trait]
impl ReleaseReader for HttpReleaseClient {
    fn url(&self) -> Result<Url> {
        Ok(self.root_url.clone())
    }

    fn root_relative_path(&self) -> &str {
        &self.relative_path
    }

    fn release_file(&self) -> &ReleaseFile<'static> {
        &self.release
    }

    fn preferred_compression(&self) -> Compression {
        self.fetch_compression
    }

    fn set_preferred_compression(&mut self, compression: Compression) {
        self.fetch_compression = compression;
    }
}

#[cfg(test)]
mod test {
    use {
        super::*,
        crate::{
            dependency::BinaryDependency, dependency_resolution::DependencyResolver, error::Result,
            io::ContentDigest, repository::release::ChecksumType,
        },
    };

    const BULLSEYE_URL: &str = "http://snapshot.debian.org/archive/debian/20211120T085721Z";

    #[tokio::test]
    async fn bullseye_release() -> Result<()> {
        let root = HttpRepositoryClient::new(BULLSEYE_URL)?;

        let release = root.release_reader("bullseye").await?;

        let packages = release.resolve_packages("main", "amd64", false).await?;
        assert_eq!(packages.len(), 58606);

        let sources = release.sources_indices_entries()?;
        assert_eq!(sources.len(), 9);

        let p = packages.iter().next().unwrap();
        assert_eq!(p.package()?, "0ad");
        assert_eq!(
            p.field_str("SHA256"),
            Some("610e9f9c41be18af516dd64a6dc1316dbfe1bb8989c52bafa556de9e381d3e29")
        );

        let p = packages.iter().last().unwrap();
        assert_eq!(p.package()?, "python3-zzzeeksphinx");
        assert_eq!(
            p.field_str("SHA256"),
            Some("6e35f5805e808c19becd3b9ce25c4cf40c41aa0cf5d81fab317198ded917fec1")
        );

        // Make sure dependency syntax parsing works.
        let mut resolver = DependencyResolver::default();
        resolver.load_binary_packages(packages.iter()).unwrap();

        for p in packages.iter() {
            resolver
                .find_direct_binary_package_dependencies(p, BinaryDependency::Depends)
                .unwrap();
        }

        let deps = resolver
            .find_transitive_binary_package_dependencies(
                p,
                [
                    BinaryDependency::Depends,
                    BinaryDependency::PreDepends,
                    BinaryDependency::Recommends,
                ]
                .into_iter(),
            )
            .unwrap();

        let sources = deps.packages_with_sources().collect::<Vec<_>>();
        assert_eq!(sources.len(), 128);

        Ok(())
    }

    #[tokio::test]
    async fn bullseye_sources() -> Result<()> {
        let root = HttpRepositoryClient::new(BULLSEYE_URL)?;

        let release = root.release_reader("bullseye").await?;

        let sources_entries = release.sources_indices_entries()?;
        assert_eq!(sources_entries.len(), 9);

        let entry = release.sources_entry("main")?;
        assert_eq!(entry.path, "main/source/Sources.xz");
        assert_eq!(
            entry.digest,
            ContentDigest::sha256_hex(
                "1801d18c1135168d5dd86a8cb85fb5cd5bd81e16174acc25d900dee11389e9cd"
            )
            .unwrap()
        );
        assert_eq!(entry.size, 8616784);
        assert_eq!(entry.component, "main");
        assert_eq!(entry.compression, Compression::Xz);

        let sources = release.resolve_sources("main").await?;
        assert_eq!(sources.len(), 30952);

        let source = sources.iter().next().unwrap();
        assert_eq!(source.binary().unwrap().collect::<Vec<_>>(), vec!["0ad"]);
        assert_eq!(source.version_str()?, "0.0.23.1-5");

        // Make sure field extraction works.
        for source in sources.iter() {
            source.required_field_str("Package")?;
            source.required_field_str("Directory")?;
            source.format()?;
            source.version()?;
            source.maintainer()?;
            source.package_dependency_fields()?;
            if let Some(packages) = source.package_list() {
                for p in packages {
                    p?;
                }
            }
            if let Some(entries) = source.checksums_sha1() {
                for entry in entries {
                    entry?;
                }
            }
            if let Some(entries) = source.checksums_sha256() {
                for entry in entries {
                    entry?;
                }
            }
            for entry in source.files()? {
                entry?;
            }
            for fetch in source.file_fetches(ChecksumType::Sha256)? {
                fetch?;
            }
        }

        let controls = sources
            .iter_with_package_name("libzstd".to_string())
            .collect::<Vec<_>>();
        assert_eq!(controls.len(), 1);

        let controls = sources
            .iter_with_binary_package("zstd".to_string())
            .collect::<Vec<_>>();
        assert_eq!(controls.len(), 1);

        let controls = sources
            .iter_with_architecture("amd64".to_string())
            .collect::<Vec<_>>();
        assert_eq!(controls.len(), 297);

        Ok(())
    }

    #[tokio::test]
    async fn bullseye_contents() -> Result<()> {
        let root = HttpRepositoryClient::new(BULLSEYE_URL)?;

        let release = root.release_reader("bullseye").await?;

        let contents_entries = release.contents_indices_entries()?;
        assert_eq!(contents_entries.len(), 126);

        let contents = release.resolve_contents("contrib", "all", false).await?;

        let packages = contents
            .packages_with_path("etc/cron.d/zfs-auto-snapshot")
            .collect::<Vec<_>>();
        assert_eq!(packages, vec!["contrib/utils/zfs-auto-snapshot"]);

        let paths = contents
            .package_paths("contrib/utils/zfs-auto-snapshot")
            .collect::<Vec<_>>();
        assert_eq!(
            paths,
            vec![
                "etc/cron.d/zfs-auto-snapshot",
                "etc/cron.daily/zfs-auto-snapshot",
                "etc/cron.hourly/zfs-auto-snapshot",
                "etc/cron.monthly/zfs-auto-snapshot",
                "etc/cron.weekly/zfs-auto-snapshot",
                "usr/sbin/zfs-auto-snapshot",
                "usr/share/doc/zfs-auto-snapshot/changelog.Debian.gz",
                "usr/share/doc/zfs-auto-snapshot/copyright",
                "usr/share/man/man8/zfs-auto-snapshot.8.gz"
            ]
        );

        Ok(())
    }
}