// yabridge: a Wine VST bridge
// Copyright (C) 2020  Robbert van der Helm
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

//! Functions to index plugins and to set up yabridge for those plugins.

use aho_corasick::AhoCorasick;
use anyhow::{Context, Result};
use lazy_static::lazy_static;
use rayon::prelude::*;
use std::collections::{BTreeMap, HashMap};
use std::path::{Path, PathBuf};
use std::process::Command;
use walkdir::WalkDir;

/// Stores the results from searching for Windows VST plugin `.dll` files and native Linux `.so`
/// files inside of a directory. These `.so` files are kept track of so we can report the current
/// installation status and to be able to prune orphan files.
#[derive(Debug)]
pub struct SearchResults {
    /// Absolute paths to the found VST2 `.dll` files.
    pub vst2_files: Vec<PathBuf>,
    /// `.dll` files skipped over during the serach. Used for printing statistics and shown when
    /// running `yabridgectl sync --verbose`.
    pub skipped_files: Vec<PathBuf>,
    /// Absolute paths to any `.so` files inside of the directory, and whether they're a symlink or
    /// a regular file.
    pub so_files: Vec<FoundFile>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum FoundFile {
    Symlink(PathBuf),
    Regular(PathBuf),
}

impl SearchResults {
    /// For every found VST2 plugin, find the associated copy or symlink of `libyabridge.so`. The
    /// returned hashmap will contain a `None` value for plugins that have not yet been set up.
    ///
    /// These two functions could be combined into a single function, but speed isn't really an
    /// issue here and it's a bit more organized this way.
    pub fn installation_status(&self) -> BTreeMap<&Path, Option<&FoundFile>> {
        let so_files: HashMap<&Path, &FoundFile> = self
            .so_files
            .iter()
            .map(|file| (file.path(), file))
            .collect();

        self.vst2_files
            .iter()
            .map(
                |path| match so_files.get(path.with_extension("so").as_path()) {
                    Some(&file) => (path.as_path(), Some(file)),
                    None => (path.as_path(), None),
                },
            )
            .collect()
    }

    /// Find all `.so` files in the search results that do not belong to a VST2 plugin `.dll` file.
    pub fn orphans(&self) -> Vec<&FoundFile> {
        // We need to store these in a map so we can easily entries with corresponding `.dll` files
        let mut orphans: HashMap<&Path, &FoundFile> = self
            .so_files
            .iter()
            .map(|file| (file.path(), file))
            .collect();
        for vst2_path in &self.vst2_files {
            orphans.remove(vst2_path.with_extension("so").as_path());
        }

        orphans.into_iter().map(|(_, file)| file).collect()
    }
}

impl FoundFile {
    /// Return the path of a found `.so` file.
    pub fn path(&self) -> &Path {
        match &self {
            FoundFile::Symlink(path) => path,
            FoundFile::Regular(path) => path,
        }
    }
}

/// Search for Windows VST2 plugins and .so files under a directory. This will return an error if
/// the directory does not exist, or if `winedump` could not be found.
pub fn index(directory: &Path) -> Result<SearchResults> {
    // First we'll find all .dll and .so files in the directory
    let (dll_files, so_files) = find_files(directory);

    lazy_static! {
        static ref VST2_AUTOMATON: AhoCorasick =
            AhoCorasick::new_auto_configured(&["VSTPluginMain", "main", "main_plugin"]);
    }

    // THne we'll figure out which `.dll` files are VST2 plugins and which should be skipped by
    // checking whether the file contains one of the VST2 entry point functions. The boolean flag in
    // this vector indicates whether it is a VST2 plugin.
    let dll_files: Vec<(PathBuf, bool)> = dll_files
        .into_par_iter()
        .map(|path| {
            let exported_functions = Command::new("winedump")
                .arg("-j")
                .arg("export")
                .arg(&path)
                .output()
                .context(
                    "Could not find 'winedump'. In some distributions this is part of a seperate \
                     Wine tools package.",
                )?
                .stdout;

            Ok((path, VST2_AUTOMATON.is_match(exported_functions)))
        })
        .collect::<Result<_>>()?;

    let mut vst2_files = Vec::new();
    let mut skipped_files = Vec::new();
    for (path, is_vst2_plugin) in dll_files {
        if is_vst2_plugin {
            vst2_files.push(path);
        } else {
            skipped_files.push(path);
        }
    }

    Ok(SearchResults {
        vst2_files,
        skipped_files,
        so_files,
    })
}

/// THe same as [index()](index), but only report found `.so` files. This avoids unnecesarily
/// filtering the found `.dll` files.
pub fn index_so_files(directory: &Path) -> Vec<FoundFile> {
    let (_, so_files) = find_files(directory);

    so_files
}

/// Find all `.dll` and `.so` files under a directory. The results are a pair of `(dll_files,
/// so_files)`.
fn find_files(directory: &Path) -> (Vec<PathBuf>, Vec<FoundFile>) {
    let mut dll_files: Vec<PathBuf> = Vec::new();
    let mut so_files: Vec<FoundFile> = Vec::new();
    // XXX: We're silently skipping directories and files we don't have permission to read. This
    //      sounds like the expected behavior, but I"m not entirely sure.
    for (file_idx, entry) in WalkDir::new(directory)
        .follow_links(true)
        .into_iter()
        .filter_map(|e| e.ok())
        .filter(|e| !e.file_type().is_dir())
        .enumerate()
    {
        // This is a bit of an odd warning, but I can see it happening that someone adds their
        // entire home directory by accident. Removing the home directory would cause yabridgectl to
        // scan for leftover `.so` files, which would of course take an enternity. This warning will
        // at least tell the user what's happening and that they can safely cancel the scan.
        if file_idx == 100_000 {
            eprintln!(
                "Indexed over 100.000 files, press Ctrl+C to cancel this operation if this was not \
                 intentional."
            )
        }

        match entry.path().extension().and_then(|os| os.to_str()) {
            Some("dll") => dll_files.push(entry.into_path()),
            Some("so") => {
                if entry.path_is_symlink() {
                    so_files.push(FoundFile::Symlink(entry.into_path()));
                } else {
                    so_files.push(FoundFile::Regular(entry.into_path()));
                }
            }
            _ => (),
        }
    }

    (dll_files, so_files)
}