//! This file defines data structures to store contents in bom file
//! as well as all management on these structures.
//! Structures `Bom`, `Target`, `SymLink`, `Source`, `NormalFile`, `FileWithOption`
//! are used to parse the bom file.
//! Structures ending with `management` are used to define managements on different levels.
//! We will construct a BomManagement for each bom file (the top bom file and all included bom files).
//! Then do real file operations on each BomManagement
use crate::error::{FILE_NOT_EXISTS_ERROR, INVALID_BOM_FILE_ERROR};
use crate::util::{
    check_file_hash, copy_dir, copy_file, copy_shared_object, create_link, dest_in_root,
    find_dependent_shared_objects, find_included_bom_file, infer_default_loader,
    lazy_check_missing_libraries, mkdir, resolve_envs, warn_on_nonempty_image_dir,
};
use serde::{Deserialize, Serialize};
use serde_yaml;
use std::collections::{HashSet, VecDeque};
use std::hash::Hash;
use std::path::PathBuf;
use std::slice::Iter;
use walkdir::WalkDir;

// The whole bom file
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Bom {
    pub includes: Option<Vec<String>>,
    pub excludes: Option<Vec<String>>,
    targets: Option<Vec<Target>>,
}

// target in a bom file.
// Each target represents the same destination.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Target {
    target: String,
    mkdirs: Option<Vec<String>>,
    createlinks: Option<Vec<SymLink>>,
    copy: Option<Vec<Source>>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SymLink {
    src: String,
    linkname: String,
}

// source in a target.
// each Source has the same `from` directory.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Source {
    from: Option<String>,
    dirs: Option<Vec<String>>,
    files: Option<Vec<NormalFile>>,
}

// A file need to be copied
// It can be only a filename; or file with multiple options to enable checking hash, renaming file, etc.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
#[serde(untagged)]
pub enum NormalFile {
    FileName(String),
    FileWithOption(FileWithOption),
}

// A file with multiple optional options
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct FileWithOption {
    name: String,
    hash: Option<String>,
    autodep: Option<bool>,
    rename: Option<String>,
}

/// all operations defined for one bom file
#[derive(Default)]
pub struct BomManagement {
    dirs_to_make: Vec<String>,
    links_to_create: Vec<(String, String)>,
    dirs_to_copy: Vec<(String, String)>,
    files_to_copy: Vec<(String, String)>,
    shared_objects_to_copy: Vec<(String, String)>,
}

/// all operations defined for one target
#[derive(Default)]
pub struct TargetManagement {
    dirs_to_make: Vec<String>,
    links_to_create: Vec<(String, String)>,
    dirs_to_copy: Vec<(String, String)>,
    files_to_copy: Vec<(String, String)>,
    files_autodep: Vec<String>,
}

/// all operations defined for one source
#[derive(Default)]
pub struct SourceManagement {
    dirs_to_copy: Vec<(String, String)>,
    files_to_copy: Vec<(String, String)>,
    files_autodep: Vec<String>,
}

impl Bom {
    /// This func will manage the root bom file. Find all included bom files, and manage files defined in each bom file
    pub fn manage_top_bom(
        &self,
        bom_file: &str,
        root_dir: &str,
        dry_run: bool,
        included_dirs: &Vec<String>,
    ) {
        warn_on_nonempty_image_dir(root_dir);
        // We need to keep the order of boms and bom managements
        let mut sorted_boms = Vec::new();
        let mut bom_managements = Vec::new();
        // find all included boms
        let all_included_boms = find_all_included_bom_files(bom_file, included_dirs);
        for included_bom in all_included_boms.iter() {
            let bom = Bom::from_yaml_file(included_bom);
            sorted_boms.push(bom.clone());
            let bom_management = bom.get_bom_management(root_dir);
            bom_managements.push(bom_management);
        }
        // remove redundant operations in each bom management
        remove_redundant(&mut bom_managements);
        // Since we have different copy options for each bom, we cannot copy all targets together.
        let mut bom_managements_iter = bom_managements.iter();
        for bom in sorted_boms.into_iter() {
            // each bom corresponds to a bom management, so the unwrap will never fail
            bom.manage_self(bom_managements_iter.next().unwrap(), dry_run);
        }
        // Try to autodep for each copydir
        if !dry_run {
            let mut made_dirs = Vec::new();
            let mut copied_shared_objects = Vec::new();
            for bom_management in bom_managements.iter() {
                let dirs = bom_management.dirs_to_make.clone();
                let shared_objects = bom_management.shared_objects_to_copy.clone();
                made_dirs.extend(dirs);
                copied_shared_objects.extend(shared_objects);
            }
            for bom_management in bom_managements.iter() {
                bom_management.autodep_for_copydirs(&made_dirs, &copied_shared_objects, root_dir);
            }
            // check all missing libraries after building the image directory
            lazy_check_missing_libraries(root_dir);
        }
    }

    /// This func will only manage the current bom file without finding included bom files
    pub fn manage_self(self, bom_management: &BomManagement, dry_run: bool) {
        let excludes = self.excludes.unwrap_or(Vec::new());
        bom_management.manage(dry_run, excludes);
    }

    /// This func will return all operations in one bom
    fn get_bom_management(self, root_dir: &str) -> BomManagement {
        let mut bom_management = BomManagement::default();
        bom_management.dirs_to_make.push(root_dir.to_string()); // init root dir
        let mut target_managements = Vec::new();
        if let Some(ref targets) = self.targets {
            for target in targets {
                let target_management = target.get_target_management(root_dir);
                target_managements.push(target_management);
            }
        }
        bom_management.add_target_managements(target_managements, root_dir);
        bom_management
    }

    /// init a bom from a yaml string
    fn from_yaml_string(yaml: &str) -> Result<Self, serde_yaml::Error> {
        serde_yaml::from_str(yaml)
    }

    /// init a bom from a yaml file
    pub fn from_yaml_file(filename: &str) -> Self {
        let file_content = std::fs::read_to_string(filename).unwrap_or_else(|e| {
            error!("cannot read bom file {}. {}.", filename, e);
            std::process::exit(FILE_NOT_EXISTS_ERROR);
        });
        Bom::from_yaml_string(&file_content).unwrap_or_else(|e| {
            error!("{} is not a valid bom file. {}.", filename, e);
            std::process::exit(INVALID_BOM_FILE_ERROR);
        })
    }
}

impl Target {
    fn get_target_management(&self, root_dir: &str) -> TargetManagement {
        let dirs_to_make = self.get_dirs_to_make(root_dir);
        let links_to_create = self.get_links_to_create(root_dir);
        let source_managements = self.get_source_managements(root_dir);
        let mut target_management = TargetManagement::default();
        target_management.dirs_to_make = dirs_to_make;
        target_management.links_to_create = links_to_create;
        for source_management in source_managements.into_iter() {
            target_management.add_source_management(source_management);
        }
        target_management
    }

    fn get_dirs_to_make(&self, root_dir: &str) -> Vec<String> {
        let mut dirs_to_make = Vec::new();
        let target_path = dest_in_root(root_dir, &self.target);
        // mkdir: target path
        dirs_to_make.push(target_path.to_string_lossy().to_string());
        // mkdir: each sub dir
        if let Some(ref dirs) = self.mkdirs {
            for dir in dirs {
                let dir_path = target_path.join(dir);
                dirs_to_make.push(dir_path.to_string_lossy().to_string());
            }
        }
        dirs_to_make
    }

    fn get_links_to_create(&self, root_dir: &str) -> Vec<(String, String)> {
        let target_path = dest_in_root(root_dir, &self.target);
        let mut links_to_create = Vec::new();
        if let Some(ref links) = self.createlinks {
            for link in links {
                let linkname = target_path.join(&link.linkname);
                links_to_create.push((link.src.clone(), linkname.to_string_lossy().to_string()));
            }
        }
        links_to_create
    }

    fn get_source_managements(&self, root_dir: &str) -> Vec<SourceManagement> {
        let target_path = dest_in_root(root_dir, &self.target);
        let mut source_managements = Vec::new();
        if let Some(ref sources) = self.copy {
            let root_dir_path = PathBuf::from(root_dir);
            let workspace_dir = root_dir_path
                .parent()
                .map(|parent| parent.to_string_lossy().to_string())
                .unwrap_or(".".to_string());
            for source in sources {
                let source_management =
                    source.get_source_management(&workspace_dir, &target_path.to_string_lossy());
                source_managements.push(source_management);
            }
        }
        source_managements
    }
}

impl Source {
    fn get_source_management(&self, workspace_dir: &str, target_dir: &str) -> SourceManagement {
        let src_dir = self
            .from
            .as_deref()
            .map(|from| {
                PathBuf::from(workspace_dir)
                    .join(from)
                    .to_string_lossy()
                    .to_string()
            })
            .unwrap_or(workspace_dir.to_string());
        let mut dirs_to_copy = self.get_dirs_to_copy(&src_dir, target_dir);
        let (files_to_copy, files_autodep) =
            self.get_files_to_copy_and_autodep(&src_dir, target_dir);
        // if files and dirs are all None, we will copy the entire `from` directory
        if None == self.files && None == self.dirs {
            let src = self.from.as_deref().unwrap_or_else(|| {
                error!("field 'from' cannot be empty");
                std::process::exit(INVALID_BOM_FILE_ERROR);
            });
            // add the "/" to the directory and will copy the entire directory
            let mut new_src = src.to_string();
            if !new_src.ends_with("/") {
                new_src.push('/');
            }
            dirs_to_copy.push((new_src, target_dir.to_string()));
        }
        SourceManagement {
            dirs_to_copy,
            files_to_copy,
            files_autodep,
        }
    }

    fn get_files_to_copy_and_autodep(
        &self,
        src_dir: &str,
        target_dir: &str,
    ) -> (Vec<(String, String)>, Vec<String>) {
        let mut files_to_copy = Vec::new();
        let mut files_autodep = Vec::new();
        if let Some(ref files) = self.files {
            for file in files {
                let (file_to_copy, file_autodep) =
                    file.get_file_to_copy_and_autodep(src_dir, target_dir);
                files_to_copy.extend(file_to_copy.into_iter());
                files_autodep.extend(file_autodep.into_iter());
            }
        }
        (files_to_copy, files_autodep)
    }

    fn get_dirs_to_copy(&self, src_dir: &str, target_dir: &str) -> Vec<(String, String)> {
        let mut dirs_to_copy = Vec::new();
        if let Some(ref dirs) = self.dirs {
            for dir in dirs {
                let src_path = PathBuf::from(src_dir).join(dir);
                dirs_to_copy.push((
                    src_path.to_string_lossy().to_string(),
                    target_dir.to_string(),
                ));
            }
        }
        dirs_to_copy
    }
}

impl NormalFile {
    fn get_file_to_copy_and_autodep(
        &self,
        src_dir: &str,
        target_dir: &str,
    ) -> (Vec<(String, String)>, Vec<String>) {
        let target_dir_path = PathBuf::from(target_dir);
        let src_dir_path = PathBuf::from(src_dir);
        let mut file_to_copy = Vec::new();
        let mut file_autodep = Vec::new();
        match self {
            NormalFile::FileName(file_name) => {
                let src_file_path = src_dir_path.join(file_name);
                // This unwrap should never fail
                let src_file_name = src_file_path
                    .file_name()
                    .unwrap()
                    .to_string_lossy()
                    .to_string();
                let src_file = src_file_path.to_string_lossy().to_string();
                let target_file = target_dir_path
                    .join(src_file_name)
                    .to_string_lossy()
                    .to_string();
                file_to_copy.push((src_file.clone(), target_file));
                // default : autodep is true
                file_autodep.push(src_file);
            }
            NormalFile::FileWithOption(file_with_option) => {
                let file_name = &file_with_option.name;
                let src_file_path = src_dir_path.join(file_name);
                //This unwrap should never fail
                let src_file_name = src_file_path
                    .file_name()
                    .unwrap()
                    .to_string_lossy()
                    .to_string();
                let src_file = src_file_path.to_string_lossy().to_string();
                // check file hash
                if let Some(ref hash) = file_with_option.hash {
                    check_file_hash(&src_file, hash);
                }
                // autodep
                if file_with_option.autodep.clone().unwrap_or(true) {
                    file_autodep.push(src_file.clone())
                }
                // rename file
                let target_file = match file_with_option.rename {
                    Some(ref rename) => target_dir_path.join(rename).to_string_lossy().to_string(),
                    None => target_dir_path
                        .join(src_file_name)
                        .to_string_lossy()
                        .to_string(),
                };
                file_to_copy.push((src_file, target_file));
            }
        }
        (file_to_copy, file_autodep)
    }
}

impl BomManagement {
    fn add_target_managements(
        &mut self,
        target_managements: Vec<TargetManagement>,
        root_dir: &str,
    ) {
        let mut files_autodep_in_bom = Vec::new();
        for mut target_management in target_managements.into_iter() {
            // First, we need to resolve environmental variables
            target_management.resolve_environmental_variables();
            let TargetManagement {
                dirs_to_make,
                links_to_create,
                dirs_to_copy,
                files_to_copy,
                files_autodep,
            } = target_management;
            self.dirs_to_make.extend(dirs_to_make.into_iter());
            self.links_to_create.extend(links_to_create.into_iter());
            self.dirs_to_copy.extend(dirs_to_copy.into_iter());
            self.files_to_copy.extend(files_to_copy.into_iter());
            files_autodep_in_bom.extend(files_autodep.into_iter());
        }

        self.autodep(files_autodep_in_bom, root_dir);
    }

    fn autodep(&mut self, files_autodep: Vec<String>, root_dir: &str) {
        let default_loader = infer_default_loader(&files_autodep);
        debug!("default loader in autodep: {:?}", default_loader);
        for file_autodep in files_autodep.iter() {
            let mut shared_objects =
                find_dependent_shared_objects(file_autodep, &default_loader, true);
            for (src, dest) in shared_objects.drain() {
                let dest_path = dest_in_root(root_dir, &dest);
                // First, we create dir to store the dependency
                // This unwrap should *NEVER* fail
                let dest_dir = dest_path.parent().unwrap().to_string_lossy().to_string();
                self.dirs_to_make.push(dest_dir);
                // Then we copy the dependency to the the dir
                let dest_file = dest_path.to_string_lossy().to_string();
                self.shared_objects_to_copy.push((src, dest_file));
            }
        }
    }

    // do real jobs
    // mkdirs, create links, copy dirs, copy files(including shared objects)
    fn manage(&self, dry_run: bool, excludes: Vec<String>) {
        let BomManagement {
            dirs_to_make,
            links_to_create,
            dirs_to_copy,
            files_to_copy,
            shared_objects_to_copy,
        } = self;
        dirs_to_make.iter().for_each(|dir| mkdir(dir, dry_run));
        links_to_create
            .iter()
            .for_each(|(src, linkname)| create_link(src, linkname, dry_run));
        dirs_to_copy
            .iter()
            .for_each(|(src, dest)| copy_dir(src, dest, dry_run, &excludes));
        files_to_copy
            .iter()
            .for_each(|(src, dest)| copy_file(src, dest, dry_run));
        shared_objects_to_copy
            .iter()
            .for_each(|(src, dest)| copy_shared_object(src, dest, dry_run));
    }

    // Try to analyse and copy dependencies for files in copydirs.
    // We do this job after we really copy dirs. This is because rsync will help deal with soft link
    // when we copy dirs. soft links pointing to file/dir out of tree will be transformed to the referent file/dir.
    // soft links pointing to files(dirs) in tree will be kept.
    // So, we can simply skip any soft link when we walk the dir.
    // This func will also not take effect if we are with dry run mode.
    // `copied_shared_objects` stores shared objects for copyfiles. We use it here to remove redundance.
    fn autodep_for_copydirs(
        &self,
        made_dirs: &Vec<String>,
        copied_shared_objects: &Vec<(String, String)>,
        root_dir: &str,
    ) {
        let BomManagement { dirs_to_copy, .. } = self;
        // get all files in copydirs. filter directories and symlinks
        let mut files_in_copied_dirs = Vec::new();
        for (src, dest) in dirs_to_copy {
            let dirname = src.split('/').last().unwrap();
            let dest_dir = PathBuf::from(dest)
                .join(dirname)
                .to_string_lossy()
                .to_string();
            for entry in WalkDir::new(dest_dir)
                .into_iter()
                .filter_map(|e| e.ok())
                .filter(|entry| entry.file_type().is_file())
            {
                files_in_copied_dirs.push(entry.path().to_string_lossy().to_string());
            }
        }
        // analyse dependencies for all files
        // TODO: fix false-positive warnings
        // When we find dependent shared objects for all files in copydir, it may report warning
        // if we can't find the shared object. For files in directories, it may be a false-positive case,
        // because we may already copy these shared objects when we copy the directory.
        // But the loader cannot find these libraries antomatically
        // since we don't know how to set the proper LD_LIBRARY_PATH env.
        // One possible method to fix this problem is that we don't directly report warning message
        // when we can't find dependencies. We return all warning message instead. Before we log these message,
        // we can check whether these libraries has already been copied when we copy the directory.
        // This method can help avoid most false-positive warnings while not affecting which files to copy.
        // User also can avoid these warnings by setting proper LD_LIBRARY_PATH in `/opt/occlum/etc/template/occlum_elf_loader.config`.
        let default_loader = infer_default_loader(&files_in_copied_dirs);
        let mut all_shared_objects = Vec::new();
        for file_path in files_in_copied_dirs.into_iter() {
            let shared_objects = find_dependent_shared_objects(&file_path, &default_loader, false);
            all_shared_objects.extend(shared_objects);
        }
        // We should not copy shared libraries already in image directory.
        // This is due to some libraries are in relative path. We will filter these libraries.
        let absolute_root_dir = std::fs::canonicalize(root_dir)
            .unwrap()
            .to_string_lossy()
            .to_string();
        all_shared_objects = all_shared_objects
            .into_iter()
            .filter(|(src, _)| !src.starts_with(&absolute_root_dir))
            .map(|(src, dest)| {
                let dest = dest_in_root(root_dir, &dest);
                (src, dest.to_string_lossy().to_string())
            })
            .collect();
        // remove redundancy
        let shared_objects =
            remove_redundant_items_in_vec(&all_shared_objects, copied_shared_objects.iter());
        // create dirs for shared objects
        let mut mkdirs = Vec::new();
        for (_, shared_object_dest) in shared_objects.iter() {
            let shared_object_dir = PathBuf::from(shared_object_dest)
                .parent()
                .unwrap()
                .to_string_lossy()
                .to_string();
            mkdirs.push(shared_object_dir);
        }
        let mkdirs = remove_redundant_items_in_vec(&mkdirs, made_dirs.iter());
        // do real operations
        mkdirs.iter().for_each(|dir| mkdir(dir, false));
        shared_objects
            .iter()
            .for_each(|(src, dest)| copy_shared_object(src, dest, false));
    }
}

impl TargetManagement {
    fn add_source_management(&mut self, source_management: SourceManagement) {
        let SourceManagement {
            dirs_to_copy,
            files_to_copy,
            files_autodep,
        } = source_management;
        self.dirs_to_copy.extend(dirs_to_copy.into_iter());
        self.files_to_copy.extend(files_to_copy.into_iter());
        self.files_autodep.extend(files_autodep.into_iter());
    }

    fn resolve_environmental_variables(&mut self) {
        self.dirs_to_make = self
            .dirs_to_make
            .iter()
            .map(|dir| resolve_envs(dir))
            .collect();
        self.links_to_create = self
            .links_to_create
            .iter()
            .map(|(src, linkname)| (resolve_envs(src), resolve_envs(linkname)))
            .collect();
        self.dirs_to_copy = self
            .dirs_to_copy
            .iter()
            .map(|(src, dest)| (resolve_envs(src), resolve_envs(dest)))
            .collect();
        self.files_to_copy = self
            .files_to_copy
            .iter()
            .map(|(src, dest)| (resolve_envs(src), resolve_envs(dest)))
            .collect();
        self.files_autodep = self
            .files_autodep
            .iter()
            .map(|file| resolve_envs(file))
            .collect();
    }
}

/// This function will return all included bom files in the order to deal with.
/// This function operates in such a way: It starts from putting the root bom into a queue,
/// In each iteration of the loop, it will fetch the first bom from the head of the queue,
/// Then it find all included files of the bom file. The all included bom files will put into the queue as well as a vector(sorted boms).
/// The loop will end if there's no more elements in the queue.
/// There is also a max_iteration bound. If the loop exceeds the bound and the queue is not empty, the function will abort the program.
/// Because excess of the bound often means there's a reference cycles in the bom tree, which is an invalid case.
/// After we visit all boms in the queue, we will get all boms sorted in the order of being included in the vector.
/// Then we will remove redundant boms in the vector. For a bom file that may exist more than one time,
/// only the last one will be kept in the final result. To remove redundancy, we will reverse the vector,
/// and only keep the first one for each duplicate bom.
fn find_all_included_bom_files(bom_file: &str, included_dirs: &Vec<String>) -> Vec<String> {
    let mut boms = VecDeque::new();
    let mut sorted_boms = Vec::new();
    const MAX_ITERATION: usize = 100;

    boms.push_back(bom_file.to_string());
    sorted_boms.push(bom_file.to_string());
    for _ in 0..MAX_ITERATION {
        if boms.is_empty() {
            break;
        }
        // This unwrap can never fail
        let current_bom = boms.pop_front().unwrap();
        let bom = Bom::from_yaml_file(&current_bom);
        // find includes for current bom
        if let Some(includes) = bom.includes {
            includes.into_iter().for_each(|include| {
                let included_bom_file =
                    find_included_bom_file(&include, &current_bom, included_dirs);
                boms.push_back(included_bom_file.clone());
                sorted_boms.push(included_bom_file);
            });
        }
    }
    if !boms.is_empty() {
        // The iteration exceeds the MAX_ITERATION and there still are elements in the queue.
        error!("The bom file number exceeds the MAX_ITERATION bound. Please check if there is including cycle.");
        std::process::exit(INVALID_BOM_FILE_ERROR);
    }
    // remove redundant boms in sorted boms
    sorted_boms.reverse();
    let mut res = remove_redundant_items_in_vec(&sorted_boms, Vec::new().iter());
    res.reverse();
    res
}

/// This function will try to remove redundant operations in all target_managements
fn remove_redundant(bom_managements: &mut Vec<BomManagement>) {
    remove_redundant_mkdir(bom_managements);
    remove_redundant_createlink(bom_managements);
    remove_redundant_copydir(bom_managements);
    remove_redundant_copyfile(bom_managements);
}

/// If multiple operation tries to make the same directory. Only the *FIRST* mkdir will reserve.
fn remove_redundant_mkdir(bom_managements: &mut Vec<BomManagement>) {
    let mut all_mkdirs = Vec::new();
    for bom_management in bom_managements.iter_mut() {
        let mkdirs = bom_management
            .dirs_to_make
            .iter()
            .map(|s| s.trim_end_matches("/").to_string())
            .collect();
        let tmp = remove_redundant_items_in_vec(&mkdirs, all_mkdirs.iter());
        bom_management.dirs_to_make = tmp.clone();
        all_mkdirs.extend(tmp);
    }
}

/// If multiple operation tries to create the same link, Only the *LAST* createlink will reserve
fn remove_redundant_createlink(bom_managements: &mut Vec<BomManagement>) {
    // reverse the array. Then we can reserve the first operation
    bom_managements.reverse();
    let mut all_createlinks = HashSet::new();
    for bom_management in bom_managements.iter_mut() {
        let mut tmp = Vec::new();
        bom_management.links_to_create.reverse();
        for (src, linkname) in bom_management.links_to_create.iter() {
            if all_createlinks.insert(linkname.clone()) {
                tmp.push((src.clone(), linkname.clone()));
            }
        }
        tmp.reverse();
        bom_management.links_to_create = tmp;
    }
    // reverse back
    bom_managements.reverse();
}

/// If multiple operation tries to copy dir to the same dest, Only the *LAST* copy dir will reserve.
/// Known limitations: if the source dir does not have filename, e.g., /home/root/, it will not be analyzed now.
fn remove_redundant_copydir(bom_managements: &mut Vec<BomManagement>) {
    // reverse, then can save the first operation
    bom_managements.reverse();
    let mut all_copydirs = HashSet::new();
    for bom_management in bom_managements.iter_mut() {
        let mut tmp = Vec::new();
        bom_management.dirs_to_copy.reverse();
        for (src, dest) in bom_management.dirs_to_copy.iter() {
            let src_path = PathBuf::from(src);
            match src_path.file_name() {
                None => tmp.push((src.clone(), dest.clone())),
                Some(filename) => {
                    let dest_dir = PathBuf::from(dest)
                        .join(filename)
                        .to_string_lossy()
                        .to_string();
                    if all_copydirs.insert(dest_dir) {
                        tmp.push((src.clone(), dest.clone()));
                    }
                }
            }
        }
        tmp.reverse();
        bom_management.dirs_to_copy = tmp;
    }
    // reverse back
    bom_managements.reverse();
}

/// If multiple files will be copied to the same destination, only the *LAST* file will be copied.
/// This function will deal with files to copy and shared objects to copy.
/// In the same bom file, if shared objects and user-written file has the same destination, the user-written file first.
fn remove_redundant_copyfile(bom_managements: &mut Vec<BomManagement>) {
    // reverse the array
    bom_managements.reverse();
    let mut all_files = HashSet::new();
    for bom_management in bom_managements.iter_mut() {
        let mut tmp_files = Vec::new();
        bom_management.files_to_copy.reverse();
        // files first
        for (src, dest) in bom_management.files_to_copy.iter() {
            if all_files.insert(dest.clone()) {
                tmp_files.push((src.clone(), dest.clone()));
            }
        }
        tmp_files.reverse();
        bom_management.files_to_copy = tmp_files;
        // then shared object
        let mut tmp_shared_objects = Vec::new();
        bom_management.shared_objects_to_copy.reverse();
        for (src, dest) in bom_management.shared_objects_to_copy.iter() {
            if all_files.insert(dest.clone()) {
                tmp_shared_objects.push((src.clone(), dest.clone()));
            }
        }
        tmp_shared_objects.reverse();
        bom_management.shared_objects_to_copy = tmp_shared_objects;
    }
    // reverse back
    bom_managements.reverse();
}

// remove redundant items in a vec. For duplicate items, only the first item will be reserved
fn remove_redundant_items_in_vec<T>(raw: &Vec<T>, excludes: Iter<'_, T>) -> Vec<T>
where
    T: Hash + Eq + Clone,
{
    let mut exists = HashSet::new();
    for item in excludes {
        exists.insert(item.clone());
    }
    let mut res = Vec::new();
    for item in raw {
        if exists.insert(item.clone()) {
            res.push(item.clone());
        }
    }
    res
}