todotxt-tui 0.2.0

use crate::{
    config::{FileWorkerConfig, SavePolicy},
    error::Result,
    todo::ToDo,
    ToDoError,
};
use notify::{
    event::{AccessKind, AccessMode, EventKind},
    Config as NotifyConfig, RecommendedWatcher, RecursiveMode, Watcher,
};
use std::fs::File;
use std::io::{BufRead, BufReader, BufWriter, Read, Write};
use std::path::Path;
use std::str::FromStr;
use std::sync::mpsc::Sender;
use std::sync::{mpsc, Arc, Mutex};
use std::{thread, time::Duration};
use todo_txt::Task;

/// Commands that can be sent to the `FileWorker` for various file-related operations.
pub enum FileWorkerCommands {
    ForceSave,
    Save,
    Load,
    Exit,
}

/// Manages file operations for the todo list and archive.
pub struct FileWorker {
    config: FileWorkerConfig,
    todo: Arc<Mutex<ToDo>>,
}

impl FileWorker {
    /// Creates a new `FileWorker` instance.
    ///
    /// # Arguments
    ///
    /// * `todo_path` - The path to the todo list file.
    /// * `archive_path` - The optional path to the archive file.
    /// * `todo` - A shared reference to the `ToDo` data structure.
    ///
    /// # Returns
    ///
    /// A `FileWorker` instance.
    pub fn new(config: FileWorkerConfig, todo: Arc<Mutex<ToDo>>) -> FileWorker {
        log::info!(
            "Init file worker: file: {:?}, archive: {:?}",
            config.todo_path,
            config.archive_path
        );
        FileWorker { config, todo }
    }

    /// Loads todo list data from the file(s).
    ///
    /// This method loads data from the main todo list file and optionally from an archive file.
    ///
    /// # Returns
    ///
    /// An `ioResult` indicating success or an error if file operations fail.
    pub fn load(&self) -> Result<()> {
        let mut todo = ToDo::default(); // TODO this can be improved
        Self::load_tasks(
            File::open(&self.config.todo_path)
                .map_err(|e| ToDoError::io_operation_failed(&self.config.todo_path, e))?,
            &mut todo,
        )?;
        log::info!(
            "Load tasks from file {}",
            self.config.todo_path.to_string_lossy()
        );
        if let Some(path) = &self.config.archive_path {
            log::info!("Load tasks from achive file {}", path.to_string_lossy());
            Self::load_tasks(
                File::open(path).map_err(|e| ToDoError::io_operation_failed(path, e))?,
                &mut todo,
            )?;
        }
        log::debug!("Loaded pending {}x tasks", todo.pending.len());
        log::debug!("Loaded done {}x tasks", todo.done.len());
        self.todo.lock().unwrap().move_data(todo);
        Ok(())
    }

    /// Loads tasks from a given reader and adds them to the provided `ToDo` instance.
    ///
    /// # Arguments
    ///
    /// * `reader` - A readable source (e.g., a file) to load tasks from.
    /// * `todo` - A mutable reference to the `ToDo` instance where tasks will be added.
    ///
    /// # Returns
    ///
    /// An `ioResult` indicating success or an error if file operations fail.
    fn load_tasks<R: Read>(reader: R, todo: &mut ToDo) -> Result<()> {
        for line in BufReader::new(reader).lines() {
            let line = line?;
            let line = line.trim();
            if line.is_empty() {
                continue;
            }
            match Task::from_str(line) {
                Ok(task) => todo.add_task(task),
                Err(e) => log::warn!("Task cannot be load due {e}: {line}"),
            }
        }
        Ok(())
    }

    /// Saves todo list data to the file(s).
    ///
    /// This method saves data to the main todo list file and optionally to an archive file.
    ///
    /// # Returns
    ///
    /// An `ioResult` indicating success or an error if file operations fail.
    fn save(&self) -> Result<()> {
        let mut f = File::create(&self.config.todo_path)
            .map_err(|e| ToDoError::io_operation_failed(&self.config.todo_path, e))?;
        let todo = self.todo.lock().unwrap();
        log::info!(
            "Saving todo task to {}{}",
            self.config.todo_path.to_string_lossy(),
            self.config
                .archive_path
                .as_ref()
                .map_or(String::from(""), |p| String::from(" and")
                    + &p.to_string_lossy()),
        );
        Self::save_tasks(&mut f, &todo.pending)?;
        match &self.config.archive_path {
            Some(s) => Self::save_tasks(
                &mut File::create(s).map_err(|err| ToDoError::io_operation_failed(s, err))?,
                &todo.done,
            ),
            None => Self::save_tasks(&mut f, &todo.done),
        }
    }

    /// Saves a list of tasks to the provided writer.
    ///
    /// # Arguments
    ///
    /// * `writer` - A writable destination (e.g., a file) where tasks will be saved.
    /// * `tasks` - A reference to a slice of tasks to be saved.
    ///
    /// # Returns
    ///
    /// An `ioResult` indicating success or an error if file operations fail.
    fn save_tasks<W: Write>(writer: &mut W, tasks: &[Task]) -> Result<()> {
        let mut writer = BufWriter::new(writer);
        for task in tasks.iter() {
            writer.write_all((task.to_string() + "\n").as_bytes())?;
        }
        Ok(())
    }

    /// Runs the `FileWorker` thread.
    ///
    /// This method starts the `FileWorker` thread and handles file-related operations and
    /// synchronization with other parts of the application.
    ///
    /// # Arguments
    ///
    /// * `autosave_duration` - The duration between automatic saves of todo data.
    /// * `handle_changes` - A flag indicating whether to handle file change events.
    ///
    /// # Returns
    ///
    /// A `Sender` that can be used to send commands to the `FileWorker` thread.
    pub fn run(self) -> Result<Sender<FileWorkerCommands>> {
        use FileWorkerCommands::*;
        let (tx, rx) = mpsc::channel::<FileWorkerCommands>();

        match self.config.save_policy {
            SavePolicy::AutoSave if !self.config.autosave_duration.is_zero() => {
                Self::spawn_autosave(tx.clone(), self.config.autosave_duration);
            }
            SavePolicy::OnChange => {
                self.todo.lock().unwrap().get_version_mut().tx = Some(tx.clone());
            }
            _ => {}
        }

        if self.config.file_watcher {
            Self::spawn_watcher(tx.clone(), &self.config.todo_path)?;
            if let Some(path) = &self.config.archive_path {
                Self::spawn_watcher(tx.clone(), path)?;
            }
        }

        thread::spawn(move || {
            let mut versions = self.todo.lock().unwrap().get_version().get_version_all();
            let mut save_queue = 0;
            for received in rx {
                log::debug!("Save queue value: {save_queue}");
                if let Err(e) = match received {
                    Save => {
                        log::trace!("Try to save Todo list.");
                        if self
                            .todo
                            .lock()
                            .unwrap()
                            .get_version()
                            .is_actual_all(versions)
                        {
                            log::info!("File Worker: Todo list is actual.");
                            Ok(())
                        } else {
                            save_queue += 1;
                            if self.config.archive_path.is_some() {
                                save_queue += 1;
                            }
                            self.save()
                        }
                    }
                    ForceSave => {
                        log::trace!("Force save Todo list.");
                        save_queue += 1;
                        if self.config.archive_path.is_some() {
                            save_queue += 1;
                        }
                        let result = self.save();
                        versions = self.todo.lock().unwrap().get_version().get_version_all();
                        result
                    }
                    Load => {
                        if save_queue == 0 {
                            let result = self.load();
                            versions = self.todo.lock().unwrap().get_version().get_version_all();
                            log::info!("Todo list updated from file.");
                            result
                        } else {
                            save_queue -= 1;
                            Ok(())
                        }
                    }
                    Exit => break,
                } {
                    log::error!("File Worker: {}", e);
                }
            }
        });
        Ok(tx)
    }

    /// Spawns an autosave thread that periodically saves the todo list data.
    ///
    /// # Arguments
    ///
    /// * `tx` - A sender for sending `FileWorkerCommands` to the `FileWorker` thread.
    /// * `duration` - The duration between automatic saves of todo data.
    fn spawn_autosave(tx: Sender<FileWorkerCommands>, duration: Duration) {
        log::trace!("Start autosaver");
        thread::spawn(move || loop {
            thread::sleep(duration);
            log::trace!("Autosave with duration {}", duration.as_secs_f64());
            if tx.send(FileWorkerCommands::Save).is_err() {
                log::trace!("Autosave end");
            }
        });
    }

    /// Spawns a file watcher thread to monitor changes to a specific file.
    ///
    /// # Arguments
    ///
    /// * `tx` - A sender for sending `FileWorkerCommands` to the `FileWorker` thread.
    /// * `path` - The path to the file to be watched for changes.
    fn spawn_watcher(tx: Sender<FileWorkerCommands>, path: &Path) -> Result<()> {
        log::trace!("Start file watcher");
        let (tx_handle, rx_handle) = std::sync::mpsc::channel();
        let mut watcher: RecommendedWatcher = Watcher::new(tx_handle, NotifyConfig::default())?;
        watcher.watch(Path::new(path), RecursiveMode::NonRecursive)?;
        let path = path.to_path_buf();
        thread::spawn(move || {
            for res in rx_handle {
                match res {
                    Ok(event) => match event.kind {
                        EventKind::Access(AccessKind::Close(AccessMode::Write)) => {
                            log::trace!("File {} changed", path.to_string_lossy());
                            if tx.send(FileWorkerCommands::Load).is_err() {
                                break;
                            };
                        }
                        _ => log::debug!("Change: {event:?}"),
                    },
                    Err(error) => log::error!("Error: {error:?}"),
                }
            }
            drop(watcher);
        });
        Ok(())
    }
}

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

    const TESTING_STRING: &str = r#"
        x (A) 2023-05-21 2023-04-30 measure space for 1 +project1 @context1 #hashtag1 due:2023-06-30
                         2023-04-30 measure space for 2 +project2 @context2           due:2023-06-30
                     (C) 2023-04-30 measure space for 3 +project3 @context3           due:2023-06-30
                                    measure space for 4 +project2 @context3 #hashtag1 due:2023-06-30
                                  x measure space for 5 +project3 @context3 #hashtag2 due:2023-06-30
                                    measure space for 6 +project3 @context2 #hashtag2 due:2023-06-30
        "#;

    #[test]
    fn test_load_tasks() -> Result<()> {
        let mut todo = ToDo::default();
        FileWorker::load_tasks(TESTING_STRING.as_bytes(), &mut todo)?;
        assert_eq!(todo.pending.len(), 4);
        assert_eq!(todo.done.len(), 2);
        assert_eq!(
            todo.pending[0].subject,
            "measure space for 2 +project2 @context2"
        );
        assert_eq!(
            todo.pending[1].subject,
            "measure space for 3 +project3 @context3"
        );
        assert_eq!(todo.pending[1].priority, 2);
        assert_eq!(
            todo.pending[2].subject,
            "measure space for 4 +project2 @context3 #hashtag1"
        );
        assert_eq!(
            todo.pending[3].subject,
            "measure space for 6 +project3 @context2 #hashtag2"
        );

        assert_eq!(
            todo.done[0].subject,
            "measure space for 1 +project1 @context1 #hashtag1"
        );
        assert_eq!(
            todo.done[1].subject,
            "measure space for 5 +project3 @context3 #hashtag2"
        );

        Ok(())
    }

    #[test]
    fn test_write_tasks() -> Result<()> {
        let mut todo = ToDo::default();
        FileWorker::load_tasks(TESTING_STRING.as_bytes(), &mut todo)?;
        let get_expected = |line: fn(&String) -> bool| {
            TESTING_STRING
                .trim()
                .lines()
                .map(|line| line.split_whitespace().collect::<Vec<_>>().join(" "))
                .filter(line)
                .collect::<Vec<String>>()
                .join("\n")
                + "\n"
        };
        let pretty_assert = |tasks, expected: &str, msg: &str| -> Result<()> {
            let mut buf: Vec<u8> = Vec::new();
            FileWorker::save_tasks(&mut buf, tasks)?;
            assert_eq!(
                expected.as_bytes(),
                buf,
                // if test failed print data in string not only in byte array
                "\n-----{}-----\nGET:\n{}\n----------------\nEXPECTED:\n{}\n",
                msg,
                String::from_utf8(buf.clone()).unwrap(),
                expected
            );
            Ok(())
        };

        pretty_assert(
            &todo.pending,
            &get_expected(|line| !line.starts_with("x ")),
            "Pending check is wrong",
        )?;
        pretty_assert(
            &todo.done,
            &get_expected(|line| line.starts_with("x ")),
            "Done check is wrong",
        )?;

        Ok(())
    }
}