// Copyright 2019 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.

#![warn(missing_docs)]

//! `component_index` provides a fuzzy search for locally-known component URLs.

use anyhow::{Context as _, Error};
use fidl_fuchsia_sys_index::{
    ComponentIndexRequest, ComponentIndexRequestStream, FuzzySearchError,
};
use fuchsia_async as fasync;
use fuchsia_component::server::ServiceFs;
use futures::prelude::*;
use std::fs;
use std::sync::Arc;

async fn run_fuzzy_search_server(
    mut stream: ComponentIndexRequestStream,
    index: Arc<Vec<String>>,
) -> Result<(), Error> {
    while let Some(ComponentIndexRequest::FuzzySearch { needle, responder }) =
        stream.try_next().await.context("Error serving fuzzy search")?
    {
        if !check_needle(&needle) {
            responder
                .send(&mut Err(FuzzySearchError::MalformedInput))
                .context("error sending response")?;
        } else {
            let res: Vec<String> = index.iter().filter(|c| c.contains(&needle)).cloned().collect();
            responder.send(&mut Ok(res)).context("error sending response")?;
        }
    }
    Ok(())
}

/// Needle only accepts [A-Z a-z 0-9 / _ - .].
fn check_needle(needle: &str) -> bool {
    return needle
        .chars()
        .all(|c| c.is_alphanumeric() || c == '/' || c == '_' || c == '-' || c == '.');
}

enum IncomingServices {
    ComponentIndex(ComponentIndexRequestStream),
}

#[fasync::run_singlethreaded]
async fn main() -> Result<(), Error> {
    let mut fs = ServiceFs::new_local();

    let index_string = fs::read_to_string("/pkg/data/component_index.txt")
        .expect("Error reading component_index.txt");
    let index_vec: Vec<String> = index_string.lines().map(|l| l.to_string()).collect();
    let index = Arc::new(index_vec);

    fs.dir("svc").add_fidl_service(IncomingServices::ComponentIndex);
    fs.take_and_serve_directory_handle()?;

    const MAX_CONCURRENT: usize = 10_000;
    let fut = fs.for_each_concurrent(MAX_CONCURRENT, |IncomingServices::ComponentIndex(stream)| {
        run_fuzzy_search_server(stream, index.clone()).unwrap_or_else(|e| println!("{:?}", e))
    });
    fut.await;
    Ok(())
}

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

    macro_rules! test_check_needle {
        (
            $(
                $test_name:ident => {
                    needle = $fuzzy_needle:expr,
                    accept = $fuzzy_accept:expr,
                }
            )+
        ) => {
            $(
                mod $test_name {
                    use super::*;
                    #[test]
                    fn test_eq() {
                        assert_eq!(check_needle($fuzzy_needle), $fuzzy_accept);
                    }
                }
            )+
        }
    }

    test_check_needle! {
        test_parse_alphanumeric => {
            needle = "F00bar",
            accept = true,
        }
        test_parse_dashes => {
            needle = "foo_bar-baz",
            accept = true,
        }
        test_parse_forward_slash => {
            needle = "foo/bar",
            accept = true,
        }
        test_parse_period => {
            needle = "foo.cmx",
            accept = true,
        }
        test_parse_false => {
            needle = "foo bar",
            accept = false,
        }
        test_parse_url => {
            // colon is invalid character
            needle = "fuchsia-pkg://",
            accept = false,
        }
        test_parse_bang => {
            needle = "hello!",
            accept = false,
        }
        test_parse_shebang => {
            needle = "#!/etc/bin",
            accept = false,
        }
        test_parse_hash => {
            needle = "package#foo.cmx",
            accept = false,
        }
    }
}