// Copyright 2022 The Goscript 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::engine::{Config, Engine, ImportKey, SourceRead};
use crate::vfs::VirtualFs;
use crate::ErrorList;
use go_parser::Map;
use std::io;
use std::path::{Path, PathBuf};
use std::rc::Rc;

pub fn run(
    config: Config,
    source: &SourceReader,
    path: &Path,
    panic_handler: Option<Rc<dyn Fn(String, String)>>,
) -> Result<(), ErrorList> {
    let engine = Engine::new();
    #[cfg(feature = "go_std")]
    engine.set_std_io(config.std_in, config.std_out, config.std_err);
    engine.run_source(
        config.trace_parser,
        config.trace_checker,
        source,
        path,
        panic_handler,
    )
}

pub struct SourceReader {
    /// base directory for non-local imports(library files)
    base_dir: Option<PathBuf>,
    /// working directory
    working_dir: PathBuf,
    /// The virtual file system from which to read files.
    vfs: Box<dyn VirtualFs>,
}

impl SourceReader {
    pub fn new(
        base_dir: Option<PathBuf>,
        working_dir: PathBuf,
        vfs: Box<dyn VirtualFs>,
    ) -> SourceReader {
        SourceReader {
            base_dir,
            working_dir,
            vfs,
        }
    }

    /// Create a SourceReader that reads from local file system.
    #[cfg(feature = "read_fs")]
    pub fn local_fs(base_dir: PathBuf, working_dir: PathBuf) -> SourceReader {
        SourceReader::new(Some(base_dir), working_dir, Box::new(crate::VfsFs {}))
    }

    /// Create a SourceReader that reads from a zip file and a string.
    #[cfg(feature = "read_fs")]
    pub fn fs_lib_and_string(
        base_dir: PathBuf,
        source: std::borrow::Cow<'static, str>,
    ) -> (SourceReader, PathBuf) {
        let temp_file_name = "temp_file.gos";
        let vfs_map_name = "vfs_map";
        let vfs_fs_name = "vfs_fs";
        (
            SourceReader::new(
                Some(Path::new(vfs_fs_name).join(base_dir)),
                PathBuf::from(format!("{}/", vfs_map_name)),
                Box::new(crate::CompoundFs::new(Map::from([
                    (
                        vfs_fs_name.to_owned(),
                        Box::new(crate::VfsFs {}) as Box<dyn VirtualFs>,
                    ),
                    (
                        vfs_map_name.to_owned(),
                        Box::new(crate::VfsMap::new(Map::from([(
                            PathBuf::from(temp_file_name),
                            source,
                        )]))),
                    ),
                ]))),
            ),
            PathBuf::from(format!("./{}", temp_file_name)),
        )
    }

    /// Creates a SourceReader that reads from a zip archive and a string.
    /// Returns the SourceReader and the path of the virtual file that contains the string.
    #[cfg(feature = "read_zip")]
    pub fn zip_lib_and_string(
        archive: std::borrow::Cow<'static, [u8]>,
        base_dir: PathBuf,
        source: std::borrow::Cow<'static, str>,
    ) -> (SourceReader, PathBuf) {
        let temp_file_name = "temp_file.gos";
        let vfs_map_name = "vfs_map";
        let vfs_zip_name = "vfs_zip";
        (
            SourceReader::new(
                Some(Path::new(vfs_zip_name).join(base_dir)),
                PathBuf::from(format!("{}/", vfs_map_name)),
                Box::new(crate::CompoundFs::new(Map::from([
                    (
                        vfs_zip_name.to_owned(),
                        Box::new(crate::VfsZip::new(archive).unwrap()) as Box<dyn VirtualFs>,
                    ),
                    (
                        vfs_map_name.to_owned(),
                        Box::new(crate::VfsMap::new(Map::from([(
                            PathBuf::from(temp_file_name),
                            source,
                        )]))),
                    ),
                ]))),
            ),
            PathBuf::from(format!("./{}", temp_file_name)),
        )
    }

    /// Creates a SourceReader that reads from a zip archive and local file system.
    /// Can be used when you want to read library files from a zip archive and user's
    /// source code from the local file system.
    #[cfg(feature = "read_zip")]
    pub fn zip_lib_and_local_fs(
        archive: std::borrow::Cow<'static, [u8]>,
        base_dir: PathBuf,
        working_dir: PathBuf,
    ) -> SourceReader {
        let vfs_fs_name = "local_fs";
        let vfs_zip_name = "vfs_zip";

        SourceReader::new(
            Some(Path::new(vfs_zip_name).join(base_dir)),
            Path::new(&vfs_fs_name).join(working_dir),
            Box::new(crate::CompoundFs::new(Map::from([
                (
                    vfs_fs_name.to_owned(),
                    Box::new(crate::VfsFs {}) as Box<dyn VirtualFs>,
                ),
                (
                    vfs_zip_name.to_owned(),
                    Box::new(crate::VfsZip::new(archive).unwrap()) as Box<dyn VirtualFs>,
                ),
            ]))),
        )
    }
}

impl SourceRead for SourceReader {
    fn working_dir(&self) -> &Path {
        &self.working_dir
    }

    fn base_dir(&self) -> Option<&Path> {
        self.base_dir.as_ref().map(|x| x.as_path())
    }

    fn read_file(&self, path: &Path) -> io::Result<String> {
        self.vfs.read_file(path)
    }

    fn read_dir(&self, path: &Path) -> io::Result<Vec<PathBuf>> {
        self.vfs.read_dir(path)
    }

    fn is_file(&self, path: &Path) -> bool {
        self.vfs.is_file(path)
    }

    fn is_dir(&self, path: &Path) -> bool {
        self.vfs.is_dir(path)
    }

    fn canonicalize_import(&self, key: &ImportKey) -> io::Result<(PathBuf, String)> {
        let mut import_path = key.path.clone();
        let path = if self.vfs.is_local(&key.path) {
            let mut wd = self.working_dir().to_owned();
            wd.push(self.vfs.strip_prefix(Path::new(&key.dir)));
            wd.push(&key.path);
            if let Some(base) = &self.base_dir() {
                if let Ok(rel) = wd.as_path().strip_prefix(base) {
                    import_path = rel.to_string_lossy().to_string()
                }
            }
            wd
        } else {
            if let Some(base) = &self.base_dir() {
                let mut p = PathBuf::new();
                p.push(base);
                p.push(&key.path);
                p
            } else {
                return Err(io::Error::new(
                    io::ErrorKind::Other,
                    format!("base dir required for path: {}", key.path),
                ));
            }
        };
        self.vfs.canonicalize_path(&path).map(|p| (p, import_path))
    }
}