elmo 0.0.1

#![doc(html_logo_url = "https://i.imgur.com/Le9EOww.png")]
//! # Introduction
//!
//! This library provides functionality for emitting, scheduling and listing notifications. It utilizes
//! an SQLite database for storing regular events (notify at a given datetime) and recurring events
//! (notify at a given pattern). Basically, it is a combination of services that communicate with the
//! notification daemon of a UNIX system, play sounds via the sound output device of the system, and
//! insert/fetch events from the database.
//!
//! # Public functions
//!
//! Five public functions are available:
//! - **`set_event`** (Either insert a new entry in the database or emit a notification directly)
//! - **`emit_event`** (Sleep for a given duration in a separate thread or emit a notification directly)
//! - **`check_events`** (Check for entries within the database that should be emitted)
//! - **`list_events`** (List entries from the database)
//! - **`delete_event`** (Delete a recurring or regular event by ID)
//!
//! **`set_event`** requires an SQlitepool from the sqlx library and needs to be called from an
//! async function, while **`emit_event`** is the synchronous variation it doesn't require a
//! database connection. An event stored into the database by **`set_event`** can only be triggered
//! by calling **`check_events`**.
//!
//! The **`check_events`** function is designed to be used in combination with a cronjob or with a daemon,
//! as it simply checks if an entry within the database matches the current datetime (or in case of
//! recurring events, if we missed it within a range of 30 minutes).
//!
//! The **`list_events`** function is
//! utilized to pretty-print events to the terminal, with a fixed format, so its use case is quite
//! specialized at the moment. In order to create a notification, you have to first establish a
//! connection to an SQLite database pool and fill out an `EventTemplate`.
//!
//! ## Example with a database
//!
//! Here we create an in-memory SQLite database with the events table and insert a single event,
//! this is not a very practical example as events stored in an in-memory database are lost when
//! the main function exits, but it shows how the function should be used.
//!
//! The function `check_events` can be used to display notifications, that are stored in a
//! database.
//!
//! ```edition2018
//! use eyre::Result;
//! use elmo_lib::{set_event, EventTemplate};
//! use sqlx::sqlite::SqlitePool;
//!
//! #[tokio::main]
//! async fn main() -> Result<()> {
//!     let pool = SqlitePool::connect("file::memory:").await?;
//!     sqlx::query(
//!         "CREATE TABLE IF NOT EXISTS events(
//!             id INTEGER PRIMARY KEY NOT NULL,
//!             name TEXT NOT NULL,
//!             description TEXT NULL,
//!             event_date TEXT NOT NULL,
//!             icon TEXT NULL,
//!             sound_file_path TEXT NULL
//!             )
//!         "
//!         ).execute(&pool).await?;
//!
//!     let new_event = EventTemplate {
//!         name: String::from("Test notification"),
//!         desc: String::from("description of an event in the future"),
//!         date_str: Some(String::from("2099-10-10T18:00")),
//!         wait_expr: None,
//!         cron_str: None,
//!         icon_name: Some(String::from("future_icon")),
//!         sound_path: None,
//!         announce: true,
//!         test_sound: false,
//!     };
//!     set_event(new_event, &pool).await?;
//!     Ok(())
//! }
//! ```
//!
//! Within the repository of this project you can locate the `migrations/1_events.sql` file, which
//! contains the SQL statements for the two tables used by the project.
//!
//! To create a new SQLite database and create the required tables issue the following command:
//! ```bash
//! sqlite3 /tmp/events.db < /path/to/elmo/migrations/1_events.sql
//! ```
//!
//! ## Example without a database
//!
//! This example doesn't utilize a database but instead creates a separate thread that sleeps for
//! the specified amount of time.
//!
//! ```edition2018
//! use elmo_lib::{emit_event, EventTemplate};
//!
//! fn main() {
//!     let new_event = EventTemplate {
//!         name: String::from("Test notification"),
//!         desc: String::from("description of a notification in 5 minutes"),
//!         date_str: None,
//!         wait_expr: Some(String::from("5 seconds")),
//!         cron_str: None,
//!         icon_name: Some(String::from("dog_icon")),
//!         sound_path: None,
//!         announce: true,
//!         test_sound: false,
//!     };
//!     emit_event(new_event);
//! }
//! ```
//!
//! # Additional hints
//!
//! To use custom icons you have to place the new images into a folder that is known to the
//! notification daemon.  Please refer to the documnetation of the software you use on your system to
//! find out how to declare custom locations, for example in [dunst](https://dunst-project.org/) you
//! simply have to add the folder to the `icon_path` variable in the configuration (dunstrc).
mod events;

use crate::events::{CronEvent, CronEventRequest, Event, EventRepo, EventRequest};
use chrono::offset::TimeZone;
use chrono::{DateTime, Local, NaiveDateTime};
use cron::Schedule;
use eyre::{eyre, Result, WrapErr};
use notify_rust::Notification;
use rodio::{Decoder, OutputStream, Sink};
pub use sqlx::sqlite::SqlitePool;

use std::fs::File;
use std::io::BufReader;
use std::str::FromStr;
use std::thread;

static SQLITE_DATE: &str = "%Y-%m-%d %H:%M:%S";
static CLI_DATE: &str = "%Y-%m-%dT%H:%M";

/// TODO Implement an optional maximum sound playing time as a parameter
/// Fetch the sound device of the system, decode the sound file and play the sound.
///
/// # Parameters
/// - `sound_file_str`L Path on the system to sound file to be played
fn play_sound(sound_file_str: &str) -> Result<()> {
    let stream = OutputStream::try_default().wrap_err("Unable to open sound output stream")?;
    let (_stream, stream_handle) = stream;
    let sink = Sink::try_new(&stream_handle).wrap_err("Unable to open sound output device")?;
    let file_buffer: BufReader<File> = BufReader::new(File::open(sound_file_str)?);
    match Decoder::new(file_buffer) {
        Ok(x) => sink.append(x),
        Err(why) => return Err(eyre!(why)),
    }
    sink.sleep_until_end();
    Ok(())
}

/// Emit a notification and play a sound if available.
///
/// # Parameters:
/// - `name`: Title of the notification window
/// - `desc`: Text body of the notification window
/// - `icon`: Optional name without extension or path of the icon for the notification
/// - `sound_file_path`: Optional full-path to the sound file (e.g. mp3, mpg, wav etc)
fn notify(
    name: String,
    desc: String,
    icon: Option<String>,
    sound_file_path: Option<String>,
) -> Result<()> {
    let icon_name = match icon {
        Some(icon) => icon,
        None => "".to_string(),
    };
    // TODO make the persistence of the notification configurable
    Notification::new()
        .summary(&name)
        .body(&desc)
        .icon(&icon_name)
        .timeout(0)
        .show()
        .unwrap();

    if sound_file_path.is_some() {
        play_sound(&sound_file_path.unwrap())?;
    }
    Ok(())
}

/// Describe how much time has passed since the notification should have been triggered.
///
/// # Parameters
///
/// - `desc`: The current notification body
/// - `diff_in_sec`: The difference between the trigger date of the event and now
fn prepare_notification_body(
    event_desc: Option<String>,
    now: NaiveDateTime,
    event_date: NaiveDateTime,
) -> String {
    let diff_in_sec = now.signed_duration_since(event_date).num_seconds();
    let mut description = match event_desc {
        Some(x) => x,
        None => "".to_string(),
    };
    if diff_in_sec > 60 {
        // Notify how much time has passed since the scheduled date
        // This useful when the system has been shutdown during the
        // scheduled event
        let time_passed = match diff_in_sec {
            i if i > 120 && i <= 7200 => format!("{} minutes ago", i / 60),
            i if i > 7200 && i <= 172800 => format!("{} hours ago", i / 3600),
            i if i > 172800 && i <= 1209600 => format!("{} days ago", i / 86400),
            i if i > 1209600 => format!("{} weeks ago", i / 604800),
            _ => format!("{} seconds ago", diff_in_sec),
        };
        if description.is_empty() {
            description.push_str(&time_passed);
        } else {
            description.push_str(format!("\n{}", time_passed).as_ref());
        }
    }
    description
}

/// Get all scheduled events matching the cron expression between the
/// start and end date, that occur after the last notification was triggered.
///
/// # Parameters
///
/// - `start_date`: Datetime in the past used to find events that were missed
///                 because the system was powered down
/// - `end_date`: Upper end of the date range to look for valid events
/// - `last_notify_date`: Datetime stored in the database when the event was triggered,
///                       used to avoid triggering multiple times in a row, when the
///                       time between each check is lower than the than the time
///                       between each trigger of this event
/// - `cron_string`: Cron expression of the event to find scheduled dates
///
/// # Returns
///
/// - `valid_events`: All scheduled dates that satisfy the conditions
fn get_valid_scheduled_dates(
    start_date: DateTime<Local>,
    end_date: NaiveDateTime,
    last_notify_date: Option<String>,
    cron_string: String,
) -> Result<Vec<NaiveDateTime>> {
    let schedule = Schedule::from_str(&cron_string)?;
    // Search for all matching events within (now - 5min) and now
    // pick the last one for the notification
    let valid_events = schedule
        .after(&start_date)
        .take(5)
        .filter(|x| x <= &Local.from_local_datetime(&end_date).unwrap())
        .map(|x| x.naive_local());
    let last_notify_date = match last_notify_date {
        Some(date) => Some(NaiveDateTime::parse_from_str(&date, SQLITE_DATE)?),
        None => None,
    };
    let valid_events: Vec<NaiveDateTime> = match last_notify_date {
        Some(date) => valid_events.filter(|x| x > &date).collect(),
        None => valid_events.collect(),
    };
    Ok(valid_events)
}

/// Search for upcoming or just missed events within all database tables.
///
/// The events table is scanned for events that either match the current date or which could not be
/// notified as the no check was executed at the scheduled datetime, the event is notified and
/// deleted from the database.
/// The recurring_events table is scanned for the most recent match to the cronjob pattern within
/// the last 30 minutes, the last notification date is updated to avoid issuing the same
/// notification multiple times.
///
/// # Parameters
///
/// - `pool`: instance of an SQLite database pool, that takes SQL requests
pub async fn check_events(pool: &SqlitePool) -> Result<()> {
    let now: NaiveDateTime = Local::now().naive_local();
    let past_events = Event::find_current_events(pool, now.to_string()).await?;
    // FIXME current problem is that if multiple events are handled at the
    // same time and each of them emits a sound, then the sound device is blocked
    // by each event
    for event in past_events {
        let event_date: NaiveDateTime =
            NaiveDateTime::parse_from_str(&event.date, SQLITE_DATE).unwrap();
        let description: String = prepare_notification_body(event.description, now, event_date);

        notify(
            event.name,
            description,
            event.icon_name,
            event.sound_file_path,
        )?;
        Event::delete_event(pool, event.id).await?;
    }

    let recurring_events = CronEvent::find_events(pool).await?;
    let past_events_check = Local
        .from_local_datetime(
            &now.checked_sub_signed(chrono::Duration::minutes(30))
                .unwrap(),
        )
        .unwrap();

    for event in recurring_events {
        let valid_dates = get_valid_scheduled_dates(
            past_events_check,
            now,
            event.last_notification,
            event.cron_string,
        )?;

        if valid_dates.is_empty() {
            continue;
        }
        let event_date: NaiveDateTime = *valid_dates.last().unwrap();
        let description = prepare_notification_body(event.description, now, event_date);
        notify(
            event.name,
            description,
            event.icon_name,
            event.sound_file_path,
        )?;
        CronEvent::update_last_notification_date(pool, event.id, event_date).await?;
        // TODO Implement an optional maximum number of repetitions
    }
    Ok(())
}

/// Check if the user-supplied `date_str` from the EventTemplate is valid.
///
///A valid date must be in the future and must have the following format: "YYYY-mm-ddTHH:MM"
///
///# Parameter
///
///- `date_str`: User-supplied string from the EventTemplate
///
///# Returns
///
///- `date`: Datetime without timezone information as String
fn parse_date(date_str: &str) -> Result<String> {
    let now: NaiveDateTime = Local::now().naive_local();
    let date = NaiveDateTime::parse_from_str(date_str, CLI_DATE)?;
    if date < now {
        return Err(eyre!("Date must be in the future, got: {}", date));
    }
    Ok(date.to_string())
}

/// Interpret a time duration string expression and add it onto the current date.
///
/// # Parameters
///
/// - `expr`: String from the argument parser containing a time duration expression.
///           Examples: 1 second, 4 minutes, 3 hours, 2 weeks 4 days 3 hours
/// - `now`: The current date and time without timezone information
///
/// # Returns:
///
/// - A new NaiveDateTime which is equal to `now` + `expr`
fn get_date_after_duration(expr: &str, now: NaiveDateTime) -> Result<String> {
    let duration = parse_duration::parse(expr);
    if duration.is_err() {
        // Get the relevant part of the error message without the Error name
        // We could also do this with .description() but that is deprecated
        return Err(eyre!(format!(
            "Invalid duration expression because {}",
            duration
                .as_ref()
                .err()
                .unwrap()
                .to_string()
                .split(": ")
                .last()
                .unwrap()
        )));
    }
    let chrono_duration = chrono::Duration::from_std(duration.unwrap())?;
    Ok(now
        .checked_add_signed(chrono_duration)
        .ok_or_else(|| eyre!("Invalid duration {}", chrono_duration))?
        .format("%Y-%m-%d %H:%M:%S")
        .to_string())
}

/// Structure describing a notification
#[derive(Clone)]
pub struct EventTemplate {
    /// Title of the notification
    pub name: String,

    /// Body of the notification message
    pub desc: String,

    /// Optional specific datetime in the future with the format YYYY-mm-ddTHH:MM
    ///
    /// # Example
    /// - `2023-10-03T15:00`
    pub date_str: Option<String>,

    /// Optional duration expression that states a time span from now to now + duration as the
    /// waiting time until the notification is issued.
    ///
    /// # Example
    /// - `5 min`
    /// - `30 minutes`
    /// - `20 seconds`
    /// - `3 days`
    pub wait_expr: Option<String>,

    /// An optional cron pattern to store in the database for recurring events.
    ///
    /// # Example
    /// - `* */5 * * * *` (Every 5 minutes)
    /// - `* 30 16 * * *` (Every day at 16:30)
    pub cron_str: Option<String>,

    /// Optional filename without extension or path of a specific icon, the icon must be placed within a
    /// folder that is known to the notification daemon.
    pub icon_name: Option<String>,

    /// Optional full-path to sound file (.mp3, .mpg, etc.)
    pub sound_path: Option<String>,

    /// Decide whether to announce the notification in advance when either `date_str`, `wait_expr`,
    /// or `cron_str` are given, the announcement shows the content of the notification and might be
    /// used to test if the EventTemplate works as expected.
    /// When `test_sound` is true and the `sound_path` points to a valid file the sound is played
    /// during the announcement.
    pub announce: bool,

    /// Only works in combination with `announce` and `sound_path`, play the sound file during the
    /// announcement to check in advance if it works.
    pub test_sound: bool,
}

/// Handle adding a new event to the database and announce the creation.
///
/// # Parameters
///
/// - `template`: Structure that defines a new event
/// - `pool`: Instance of an SQLite database pool, that takes SQL requests
async fn schedule_event(template: EventTemplate, pool: &SqlitePool) -> Result<()> {
    let mut notify_at = String::from("");
    let mut date: String = String::from("");
    // TODO Make sure that only valid dates are entered into the database
    if let Some(ref date_str) = &template.date_str {
        date = parse_date(date_str)?;
    } else if let Some(ref expr) = &template.wait_expr {
        let now: NaiveDateTime = Local::now().naive_local();
        date = get_date_after_duration(expr, now)?;
    } else if let Some(ref cron_expr) = &template.cron_str {
        // Verify that the cron expression is valid
        // TODO only take the last 5 elements from the expected 6 elements from the
        // user as the first element describes seconds which is meaningless if we check
        // with crontab
        Schedule::from_str(cron_expr)?;
        // TODO implement parse to human readable cron
        notify_at = format!("trigger at {}", cron_expr);
        let request = CronEventRequest {
            name: template.name.to_string(),
            description: template.desc.to_string(),
            cron_string: cron_expr.to_string(),
            icon_name: template.icon_name.as_ref().map(|x| x.to_string()),
            sound_file_path: template.sound_path.as_ref().map(|x| x.to_string()),
        };
        CronEvent::create_event(pool, request).await?;
    }
    if !date.is_empty() {
        notify_at = date.clone();
        let request = EventRequest {
            name: template.name.to_string(),
            description: template.desc.to_string(),
            date,
            icon_name: template.icon_name.as_ref().map(|x| x.to_string()),
            sound_file_path: template.sound_path.as_ref().map(|x| x.to_string()),
        };
        Event::create_event(pool, request).await?;
    }

    if template.announce {
        let mut with_sound = String::from("");
        if template.test_sound {
            with_sound = String::from("\n(play the sound as a test..)")
        }
        let display_name = String::from("New notification created");
        let display_desc = format!(
            "Title:\n{}\n\nDescription:\n{}\n\nNotify at:\n{}\n{}",
            template.name, template.desc, notify_at, with_sound
        );
        notify(
            display_name,
            display_desc,
            template.icon_name.to_owned(),
            match template.test_sound {
                true => template.sound_path.to_owned(),
                false => None,
            },
        )?;
    }
    Ok(())
}

/// Create a delayed, recurring or direct notification.
///
/// # Parameters
///
/// - `template`: Structure that defines a new event
/// - `pool`: Optional instance of a Sqlite database pool
///
/// # Errors
///
/// Possible errors are:
/// - an invalid connection to the database
/// - unable to access the sound output device
/// - An invalid input date, which is either not in the format of
///   YYYY-mm-ddTHH:MM or smaller than now
/// - An invalid duration value for the `--wait` argument
/// - An incorrect cron string
pub async fn set_event(template: EventTemplate, pool: &SqlitePool) -> Result<()> {
    if template.date_str.is_some() || template.cron_str.is_some() || template.wait_expr.is_some() {
        schedule_event(template, pool).await?;
    } else {
        notify(
            template.name.to_owned(),
            template.desc.to_owned(),
            template.icon_name.to_owned(),
            template.sound_path.to_owned(),
        )?;
    }
    Ok(())
}

pub fn emit_event(template: EventTemplate) -> Result<()> {
    let local_dates: Vec<NaiveDateTime>;
    if let Some(ref date_str) = template.date_str {
        let date = parse_date(&date_str.to_string())?;
        local_dates = vec![NaiveDateTime::parse_from_str(&date, SQLITE_DATE)
            .wrap_err(format!("Invalid date {}", date))?]
    } else if let Some(ref expr) = template.wait_expr {
        let now: NaiveDateTime = Local::now().naive_local();
        let date = get_date_after_duration(expr.as_ref(), now)?;
        local_dates = vec![NaiveDateTime::parse_from_str(&date, SQLITE_DATE)
            .wrap_err(format!("Invalid date {}", date))?]
    } else if let Some(ref cron_expr) = template.cron_str {
        // TODO make the amount of dates configurable
        local_dates = Schedule::from_str(cron_expr.as_ref())?
            .upcoming(Local)
            .take(50)
            .map(|date| date.naive_local())
            .collect();
    } else {
        notify(
            template.name.to_string(),
            template.desc.to_string(),
            template.icon_name,
            template.sound_path,
        )?;
        return Ok(());
    }
    let dates = local_dates;
    // let name = template.name.to_string();
    // let desc = template.desc.to_string();
    // let icon = template.icon_name.map(|x| x.to_string());
    // let sound = template.sound_path.map(|x| x.to_string());
    std::thread::spawn(move || {
        for date in dates {
            let now: NaiveDateTime = Local::now().naive_local();
            let duration = date.signed_duration_since(now);
            thread::sleep(duration.to_std().unwrap());
            let notify_result = notify(
                template.name.to_string(),
                template.desc.to_string(),
                template.icon_name.as_ref().map(|x| x.to_string()),
                template.sound_path.as_ref().map(|x| x.to_string()),
            );
            assert!(
                !notify_result.is_err(),
                "Notification failed {}",
                notify_result.err().unwrap()
            );
        }
    });
    Ok(())
}

/// Colorful output to the terminal of all listed events
///
/// # Parameters:
///
/// - `response`: Either a vector of Event objects from the `events` table
///               or a vector or CronEvent objects from the 'recurring_events` table'.
///               Sorting of any kind has to be performed in advance.
/// - `print_function`: Specific function used to print the particular kind of object.
///                     Currently either `print_event` or `print_cron`.
fn print_event_response<T>(
    response: &[T],
    print_function: fn(&mut Box<term::StdoutTerminal>, event: &T),
) {
    let mut terminal = term::stdout().unwrap();
    for event in response {
        print_function(&mut terminal, event);
    }
}

fn print_header(id: i64, terminal: &mut Box<term::StdoutTerminal>) {
    terminal.fg(term::color::BRIGHT_YELLOW).unwrap();
    terminal.bg(term::color::BRIGHT_BLACK).unwrap();
    terminal.attr(term::Attr::Bold).unwrap();
    print!(" {0: <93}", format!("Event id: {}", id));
    terminal.reset().unwrap();
    println!();
}

fn print_title(title: &str, terminal: &mut Box<term::StdoutTerminal>) {
    terminal.fg(term::color::BRIGHT_YELLOW).unwrap();
    terminal.bg(term::color::BRIGHT_BLACK).unwrap();
    terminal.attr(term::Attr::Underline(true)).unwrap();
    print!(" {0: <27}", title);
    terminal.reset().unwrap();
}

fn print_content(content: &str, terminal: &mut Box<term::StdoutTerminal>) {
    terminal.fg(term::color::MAGENTA).unwrap();
    terminal.bg(term::color::BRIGHT_YELLOW).unwrap();
    terminal.attr(term::Attr::Bold).unwrap();
    print!(" {0: <65}", content);
    terminal.reset().unwrap();
    println!();
}

/// Colorful output to the terminal of a single event
///
/// # Parameters:
///
/// - `terminal`: Terminal writer with capabilities for changing colors and style
/// - `event`: A single row from the `events` database table
fn print_event(terminal: &mut Box<term::StdoutTerminal>, event: &Event) {
    print_header(event.id, terminal);
    print_title("Datetime", terminal);
    print_content(&event.date, terminal);
    print_title("Name", terminal);
    print_content(&event.name, terminal);
    print_title("Description", terminal);
    let desc = match &event.description {
        Some(x) => x,
        None => "---",
    };
    print_content(desc, terminal);
    print_title("Icon", terminal);
    let icon_name = match &event.icon_name {
        Some(x) => x,
        None => "---",
    };
    print_content(icon_name, terminal);
    print_title("Sound file", terminal);
    let sound_file_path = match &event.sound_file_path {
        Some(x) => x,
        None => "---",
    };
    print_content(sound_file_path, terminal);
    println!();
}

/// Parse the cron expression and get the next valid date that matches it
///
/// # Parameters
///
/// - `cron_string`: Cron expression with 6 fields (sec, min, hour, day(month), month, day(week))
///
/// # Result
///
/// - `upcoming`: The next matching date if any as DateTime without time zone information
fn get_upcoming_scheduled_date(cron_string: String) -> Result<NaiveDateTime> {
    let schedule = Schedule::from_str(&cron_string)?;
    let upcoming = schedule
        .upcoming(Local)
        .next()
        .ok_or_else(|| eyre!("No upcoming date found"))?
        .naive_local();
    Ok(upcoming)
}

// TODO write the events in order of their next notification
/// Colorful output to the terminal of a single recurring event
///
/// # Parameters:
///
/// - `terminal`: Terminal writer with capabilities for changing colors and style
/// - `event`: A single row from the `recurring_events` database table
fn print_cron(terminal: &mut Box<term::StdoutTerminal>, event: &CronEvent) {
    print_header(event.id, terminal);
    print_title("Next notification", terminal);
    let next_notify = get_upcoming_scheduled_date(event.cron_string.clone()).unwrap();
    print_content(&next_notify.to_string(), terminal);
    print_title("Last notification", terminal);
    let last_notify = match &event.last_notification {
        Some(date) => date.to_string(),
        None => "---".to_string(),
    };
    print_content(&last_notify, terminal);
    print_title("Name", terminal);
    print_content(&event.name, terminal);
    print_title("Description", terminal);
    let desc = match &event.description {
        Some(x) => x,
        None => "---",
    };
    print_content(desc, terminal);
    print_title("Cron expression", terminal);
    print_content(&event.cron_string, terminal);
    print_title("Icon", terminal);
    let icon_name = match &event.icon_name {
        Some(x) => x,
        None => "---",
    };
    print_content(icon_name, terminal);
    print_title("Sound file", terminal);
    let sound_file_path = match &event.sound_file_path {
        Some(x) => x,
        None => "---",
    };
    print_content(sound_file_path, terminal);
    println!();
}

/// List upcoming events or recurring events within the CLI with colorful output.
///
/// The colors are dependent on your bash color profile.
///
/// # Parameters
///
/// - `pool`: instance of an SQLite database pool, that takes SQL requests
/// - `expression`: Optional duration expression as String reference like `30 min` or `10 days`,
/// that limits the output to all events within now -> now + expression
/// - `cron_mode`: When set recurring events are listed instead of regular events from the events
/// table
pub async fn list_events(
    pool: &SqlitePool,
    expression: Option<&str>,
    cron_mode: bool,
) -> Result<()> {
    let now: NaiveDateTime = Local::now().naive_local();
    if let Some(expr) = expression {
        let end_date = get_date_after_duration(expr, now)?;
        print_event_response::<Event>(
            &Event::find_future_events(pool, now.to_string(), Some(end_date)).await?,
            print_event,
        );
    } else if cron_mode {
        print_event_response::<CronEvent>(&CronEvent::find_events(pool).await?, print_cron);
    } else {
        // TODO sort the events by their next notification date before printing them
        print_event_response::<Event>(
            &Event::find_future_events(pool, now.to_string(), None).await?,
            print_event,
        );
    }
    Ok(())
}

fn deletion_confirmation(event_id: i64, event_name: String) -> bool {
    loop {
        let mut input = String::new();
        println!(
            "Delete event {} with the name: {} (Y/n)",
            event_id, event_name
        );
        std::io::stdin()
            .read_line(&mut input)
            .expect("Unable to read user input");
        if !input.is_ascii() {
            println!("Input contains non ASCII values ...");
            continue;
        }
        match input.chars().next().unwrap().to_ascii_lowercase() {
            'y' | 'j' | '\n' => return true,
            'n' => return false,
            _ => continue,
        }
    }
}

/// Delete a recurring or regular event by ID.
///
/// # Parameters
/// - `pool`: instance of an SQLite database pool, that takes SQL requests
/// - `id`: ID of the event in the database
/// - `cron_mode`: Delete recurring events when this is `true`
/// - `confirm`: Ask the user for confirmation unless this is `true`
pub async fn delete_event(
    pool: &SqlitePool,
    id: i64,
    cron_mode: bool,
    confirm: bool,
) -> Result<()> {
    if !confirm {
        if cron_mode {
            let event = &CronEvent::get_event(pool, id).await;
            match event {
                Ok(ev) => {
                    if !deletion_confirmation(ev.id, ev.name.clone()) {
                        return Err(eyre!("Deletion aborted by the user"));
                    }
                }
                Err(err) => {
                    return Err(eyre!(
                        "Deletion of the recurring event with ID {} failed, due to {}",
                        id,
                        err
                    ))
                }
            }
        } else {
            let event = &Event::get_event(pool, id).await;
            match event {
                Ok(ev) => {
                    if !deletion_confirmation(ev.id, ev.name.clone()) {
                        return Err(eyre!("Deletion aborted by the user"));
                    }
                }
                Err(err) => {
                    return Err(eyre!(
                        "Deletion of the event with ID {} failed, due to {}",
                        id,
                        err
                    ))
                }
            }
        }
    }
    match cron_mode {
        true => &CronEvent::delete_event(pool, id).await?,
        false => &Event::delete_event(pool, id).await?,
    };
    Ok(())
}

pub async fn prepare_environment(pool: &SqlitePool) -> Result<()> {
    Event::create_table(pool).await?;
    CronEvent::create_table(pool).await?;
    Ok(())
}

#[cfg(test)]
mod tests {
    use chrono::NaiveDate;

    use super::*;

    #[test]
    fn test_get_valid_scheduled_dates_with_no_valid_dates() -> Result<(), String> {
        let start_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 0, 0);
        let end_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 5, 0);
        let last_notify_date = None;
        let cron_string = String::from("0 30 16 * * *");
        let expected_result = vec![];
        let result = get_valid_scheduled_dates(
            Local.from_local_datetime(&start_date).unwrap(),
            end_date,
            last_notify_date,
            cron_string,
        )
        .unwrap();
        assert_eq!(result, expected_result);
        Ok(())
    }

    #[test]
    fn test_get_valid_scheduled_dates_with_one_valid_date() -> Result<(), String> {
        let start_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 0, 0);
        let end_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 5, 0);
        let last_notify_date = None;
        let cron_string = String::from("0 3 16 * * *");
        let expected_result = vec![NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 3, 0)];
        let result = get_valid_scheduled_dates(
            Local.from_local_datetime(&start_date).unwrap(),
            end_date,
            last_notify_date,
            cron_string,
        )
        .unwrap();
        assert_eq!(result, expected_result);
        Ok(())
    }

    #[test]
    fn test_get_valid_scheduled_dates_with_multiple_matches() -> Result<(), String> {
        let start_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 0, 0);
        let end_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 10, 0);
        let last_notify_date = None;
        let cron_string = String::from("0 */3 * * * *");
        let expected_result = vec![
            NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 3, 0),
            NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 6, 0),
            NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 9, 0),
        ];
        let result = get_valid_scheduled_dates(
            Local.from_local_datetime(&start_date).unwrap(),
            end_date,
            last_notify_date,
            cron_string,
        )
        .unwrap();
        assert_eq!(result, expected_result);
        Ok(())
    }

    #[test]
    fn test_get_valid_scheduled_dates_with_last_notify_hide_past_events() -> Result<(), String> {
        let start_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 0, 0);
        let end_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 10, 0);
        let last_notify_date = Some(String::from("2021-09-10 16:05:00"));
        let cron_string = String::from("0 */5 * * * *");
        let expected_result = vec![NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 10, 0)];
        let result = get_valid_scheduled_dates(
            Local.from_local_datetime(&start_date).unwrap(),
            end_date,
            last_notify_date,
            cron_string,
        )
        .unwrap();
        assert_eq!(result, expected_result);
        Ok(())
    }

    #[test]
    fn test_get_valid_scheduled_dates_with_last_notify_no_matches() -> Result<(), String> {
        let start_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 0, 0);
        let end_date = NaiveDate::from_ymd(2021, 9, 10).and_hms(16, 15, 0);
        let last_notify_date = Some(String::from("2021-09-10 16:00:00"));
        let cron_string = String::from("0 */30 * * * *");
        let expected_result = vec![];
        let result = get_valid_scheduled_dates(
            Local.from_local_datetime(&start_date).unwrap(),
            end_date,
            last_notify_date,
            cron_string,
        )
        .unwrap();
        assert_eq!(result, expected_result);
        Ok(())
    }
}