use crate::common::Common;
use crate::common_directory::Directories;
use crate::common_messages::Messages;
use crate::common_traits::{DebugPrint, PrintResults, SaveResults};
use crossbeam_channel::Receiver;
use std::collections::BTreeMap;
use std::fs;
use std::fs::{File, Metadata};
use std::io::Write;
use std::path::PathBuf;
use std::time::{SystemTime, UNIX_EPOCH};

/// Enum with values which show if folder is empty.
/// In function "optimize_folders" automatically "Maybe" is changed to "Yes", so it is not necessary to put it here
#[derive(Eq, PartialEq, Copy, Clone)]
enum FolderEmptiness {
    No,
    Maybe,
}

/// Struct assigned to each checked folder with parent path(used to ignore parent if children are not empty) and flag which shows if folder is empty
#[derive(Clone)]
pub struct FolderEntry {
    parent_path: Option<PathBuf>, // Usable only when finding
    is_empty: FolderEmptiness,
    pub modified_date: u64,
}

/// Struct to store most basics info about all folder
pub struct EmptyFolder {
    information: Info,
    delete_folders: bool,
    text_messages: Messages,
    empty_folder_list: BTreeMap<PathBuf, FolderEntry>, // Path, FolderEntry
    directories: Directories,
    stopped_search: bool,
}

/// Info struck with helpful information's about results
#[derive(Default)]
pub struct Info {
    number_of_checked_folders: usize,
    pub number_of_empty_folders: usize,
}
impl Info {
    pub fn new() -> Self {
        Default::default()
    }
}

/// Method implementation for EmptyFolder
impl EmptyFolder {
    /// New function providing basics values
    pub fn new() -> Self {
        Self {
            information: Default::default(),
            delete_folders: false,
            text_messages: Messages::new(),
            empty_folder_list: Default::default(),
            directories: Directories::new(),
            stopped_search: false,
        }
    }

    pub fn get_stopped_search(&self) -> bool {
        self.stopped_search
    }

    pub const fn get_empty_folder_list(&self) -> &BTreeMap<PathBuf, FolderEntry> {
        &self.empty_folder_list
    }

    pub const fn get_text_messages(&self) -> &Messages {
        &self.text_messages
    }
    pub const fn get_information(&self) -> &Info {
        &self.information
    }

    /// Public function used by CLI to search for empty folders
    pub fn find_empty_folders(&mut self, rx: Option<&Receiver<()>>) {
        self.directories.optimize_directories(true, &mut self.text_messages);
        if !self.check_for_empty_folders(rx) {
            self.stopped_search = true;
            return;
        }
        self.optimize_folders();
        if self.delete_folders {
            self.delete_empty_folders();
        }
        self.debug_print();
    }

    pub fn set_delete_folder(&mut self, delete_folder: bool) {
        self.delete_folders = delete_folder;
    }

    /// Clean directory tree
    /// If directory contains only 2 empty folders, then this directory should be removed instead two empty folders inside because it will produce another empty folder.
    fn optimize_folders(&mut self) {
        let mut new_directory_folders: BTreeMap<PathBuf, FolderEntry> = Default::default();

        for (name, folder_entry) in &self.empty_folder_list {
            match &folder_entry.parent_path {
                Some(t) => {
                    if !self.empty_folder_list.contains_key(t) {
                        new_directory_folders.insert(name.clone(), folder_entry.clone());
                    }
                }
                None => {
                    new_directory_folders.insert(name.clone(), folder_entry.clone());
                }
            }
        }
        self.empty_folder_list = new_directory_folders;
        self.information.number_of_empty_folders = self.empty_folder_list.len();
    }

    /// Function to check if folder are empty.
    /// Parameter initial_checking for second check before deleting to be sure that checked folder is still empty
    fn check_for_empty_folders(&mut self, rx: Option<&Receiver<()>>) -> bool {
        let start_time: SystemTime = SystemTime::now();
        let mut folders_to_check: Vec<PathBuf> = Vec::with_capacity(1024 * 2); // This should be small enough too not see to big difference and big enough to store most of paths without needing to resize vector
        let mut folders_checked: BTreeMap<PathBuf, FolderEntry> = Default::default();

        // Add root folders for finding
        for id in &self.directories.included_directories {
            folders_checked.insert(
                id.clone(),
                FolderEntry {
                    parent_path: None,
                    is_empty: FolderEmptiness::Maybe,
                    modified_date: 0,
                },
            );
            folders_to_check.push(id.clone());
        }

        while !folders_to_check.is_empty() {
            if rx.is_some() && rx.unwrap().try_recv().is_ok() {
                return false;
            }
            self.information.number_of_checked_folders += 1;
            let current_folder = folders_to_check.pop().unwrap();
            // Checked folder may be deleted or we may not have permissions to open it so we assume that this folder is not be empty
            let read_dir = match fs::read_dir(&current_folder) {
                Ok(t) => t,
                Err(_) => {
                    folders_checked.get_mut(&current_folder).unwrap().is_empty = FolderEmptiness::No;
                    continue;
                }
            };

            for entry in read_dir {
                let entry_data = match entry {
                    Ok(t) => t,
                    Err(_) => continue, //Permissions denied
                };
                let metadata: Metadata = match entry_data.metadata() {
                    Ok(t) => t,
                    Err(_) => continue, //Permissions denied
                };
                // If child is dir, still folder may be considered as empty if all children are only directories.
                if metadata.is_dir() {
                    let next_folder = current_folder.join(entry_data.file_name());
                    folders_to_check.push(next_folder.clone());
                    folders_checked.insert(
                        next_folder.clone(),
                        FolderEntry {
                            parent_path: Option::from(current_folder.clone()),
                            is_empty: FolderEmptiness::Maybe,
                            modified_date: match metadata.modified() {
                                Ok(t) => match t.duration_since(UNIX_EPOCH) {
                                    Ok(d) => d.as_secs(),
                                    Err(_) => {
                                        self.text_messages.warnings.push(format!("Folder {} seems to be modified before Unix Epoch.", current_folder.display()));
                                        0
                                    }
                                },
                                Err(_) => {
                                    self.text_messages.warnings.push(format!("Failed to read modification date of folder {}", current_folder.display()));
                                    continue;
                                }
                            },
                        },
                    );
                } else {
                    // Not folder so it may be a file or symbolic link so it isn't empty
                    folders_checked.get_mut(&current_folder).unwrap().is_empty = FolderEmptiness::No;
                    let mut d = folders_checked.get_mut(&current_folder).unwrap();
                    // Loop to recursively set as non empty this and all his parent folders
                    loop {
                        d.is_empty = FolderEmptiness::No;
                        if d.parent_path != None {
                            let cf = d.parent_path.clone().unwrap();
                            d = folders_checked.get_mut(&cf).unwrap();
                        } else {
                            break;
                        }
                    }
                }
            }
        }

        // We need to set empty folder list
        #[allow(unused_mut)] // Used is later by Windows build
        for (mut name, folder_entry) in folders_checked {
            if folder_entry.is_empty != FolderEmptiness::No {
                self.empty_folder_list.insert(name, folder_entry);
            }
        }

        Common::print_time(start_time, SystemTime::now(), "check_for_empty_folder".to_string());
        true
    }

    /// Deletes earlier found empty folders
    fn delete_empty_folders(&mut self) {
        let start_time: SystemTime = SystemTime::now();
        // Folders may be deleted or require too big privileges
        for name in self.empty_folder_list.keys() {
            match fs::remove_dir_all(name) {
                Ok(_) => (),
                Err(_) => self.text_messages.warnings.push(format!("Failed to remove folder {}", name.display())),
            };
        }

        Common::print_time(start_time, SystemTime::now(), "delete_files".to_string());
    }

    /// Set included dir which needs to be relative, exists etc.
    pub fn set_included_directory(&mut self, included_directory: String) {
        self.directories.set_included_directory(included_directory, &mut self.text_messages);
    }
}
impl Default for EmptyFolder {
    fn default() -> Self {
        Self::new()
    }
}

impl DebugPrint for EmptyFolder {
    #[allow(dead_code)]
    #[allow(unreachable_code)]
    fn debug_print(&self) {
        #[cfg(not(debug_assertions))]
        {
            return;
        }

        println!("---------------DEBUG PRINT---------------");
        println!("Number of all checked folders - {}", self.information.number_of_checked_folders);
        println!("Number of empty folders - {}", self.information.number_of_empty_folders);
        println!("Included directories - {:?}", self.directories.included_directories);
        println!("-----------------------------------------");
    }
}
impl SaveResults for EmptyFolder {
    fn save_results_to_file(&mut self, file_name: &str) -> bool {
        let start_time: SystemTime = SystemTime::now();
        let file_name: String = match file_name {
            "" => "results.txt".to_string(),
            k => k.to_string(),
        };

        let mut file = match File::create(&file_name) {
            Ok(t) => t,
            Err(_) => {
                self.text_messages.errors.push("Failed to create file ".to_string() + file_name.as_str());
                return false;
            }
        };

        if writeln!(file, "Results of searching {:?} with excluded directories {:?}", self.directories.included_directories, self.directories.excluded_directories).is_err() {
            self.text_messages.errors.push("Failed to save results to file ".to_string() + file_name.as_str());
            return false;
        }

        if !self.empty_folder_list.is_empty() {
            writeln!(file, "-------------------------------------------------Empty folder list-------------------------------------------------").unwrap();
            writeln!(file, "Found {} empty folders", self.information.number_of_empty_folders).unwrap();
            for name in self.empty_folder_list.keys() {
                writeln!(file, "{}", name.display()).unwrap();
            }
        } else {
            write!(file, "Not found any empty folders.").unwrap();
        }
        Common::print_time(start_time, SystemTime::now(), "save_results_to_file".to_string());
        true
    }
}
impl PrintResults for EmptyFolder {
    /// Prints basic info about empty folders // TODO print better
    fn print_results(&self) {
        if !self.empty_folder_list.is_empty() {
            println!("Found {} empty folders", self.empty_folder_list.len());
        }
        for name in self.empty_folder_list.keys() {
            println!("{}", name.display());
        }
    }
}