tmux-backup 0.5.15

//! High-level representation of a backup for catalog operations and reporting.

use std::fmt;
use std::path::PathBuf;

use chrono::{Duration, NaiveDateTime};
use clap::ValueEnum;

/// Quick access, high-level representation of a backup.
///
/// `Backup` provides only information which can be derived from the file name, avoiding to open
/// the file, deal with the format, parse the metadata, etc.
///
/// This is sufficient for the [`Catalog`](crate::management::catalog::Catalog) to list backups
/// and decide whether or not a backup should be deleted or kept.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct Backup {
    /// Path to the backup file.
    pub filepath: PathBuf,

    /// Backup date.
    pub creation_date: NaiveDateTime,
}

impl Backup {
    /// Return a string representing the duration since the backup file was created.
    ///
    // This function can only receive properly formatted files
    pub fn age(&self, now: NaiveDateTime) -> String {
        let duration = now.signed_duration_since(self.creation_date);
        let duration_secs = duration.num_seconds();

        // Month scale -> "n months ago"
        let month = Duration::weeks(4).num_seconds();
        if duration_secs >= 2 * month {
            return format!("{} months", duration_secs / month);
        }
        if duration_secs >= month {
            return "1 month".into();
        }

        // Week scale -> "n weeks ago"
        let week = Duration::weeks(1).num_seconds();
        if duration_secs >= 2 * week {
            return format!("{} weeks", duration_secs / week);
        }
        if duration_secs >= week {
            return "1 week".into();
        }

        // Day scale -> "n days ago"
        let day = Duration::days(1).num_seconds();
        if duration_secs >= 2 * day {
            return format!("{} days", duration_secs / day);
        }
        if duration_secs >= day {
            return "1 day".into();
        }

        // Hour scale -> "n hours ago"
        let hour = Duration::hours(1).num_seconds();
        if duration_secs >= 2 * hour {
            return format!("{} hours", duration_secs / hour);
        }
        if duration_secs >= hour {
            return "1 hour".into();
        }

        // Minute scale -> "n minutes ago"
        let minute = Duration::minutes(1).num_seconds();
        if duration_secs >= 2 * minute {
            return format!("{} minutes", duration_secs / minute);
        }
        if duration_secs >= minute {
            return "1 minute".into();
        }

        format!("{duration_secs} seconds")
    }
}

/// Which subset of backups to print.
#[derive(Debug, Clone, ValueEnum)]
pub enum BackupStatus {
    /// Retainable backups only.
    Retainable,

    /// Purgeable backups only.
    Purgeable,
}

impl fmt::Display for BackupStatus {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            BackupStatus::Retainable => write!(f, "{:12}", "retainable"),
            BackupStatus::Purgeable => write!(f, "{:12}", "purgeable"),
        }
    }
}

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

    /// Helper to create a backup with a given datetime for testing.
    fn backup_at(year: i32, month: u32, day: u32, hour: u32, min: u32, sec: u32) -> Backup {
        Backup {
            filepath: PathBuf::from("/tmp/backup.tar.zst"),
            creation_date: NaiveDate::from_ymd_opt(year, month, day)
                .unwrap()
                .and_hms_opt(hour, min, sec)
                .unwrap(),
        }
    }

    fn datetime(year: i32, month: u32, day: u32, hour: u32, min: u32, sec: u32) -> NaiveDateTime {
        NaiveDate::from_ymd_opt(year, month, day)
            .unwrap()
            .and_hms_opt(hour, min, sec)
            .unwrap()
    }

    mod age_formatting {
        use super::*;

        #[test]
        fn fresh_backup_shows_seconds() {
            let backup = backup_at(2024, 6, 15, 10, 30, 0);
            let now = datetime(2024, 6, 15, 10, 30, 45);

            assert_eq!(backup.age(now), "45 seconds");
        }

        #[test]
        fn zero_seconds_is_still_seconds() {
            let backup = backup_at(2024, 6, 15, 10, 30, 0);
            let now = datetime(2024, 6, 15, 10, 30, 0);

            assert_eq!(backup.age(now), "0 seconds");
        }

        #[test]
        fn exactly_one_minute() {
            let backup = backup_at(2024, 6, 15, 10, 30, 0);
            let now = datetime(2024, 6, 15, 10, 31, 0);

            assert_eq!(backup.age(now), "1 minute");
        }

        #[test]
        fn just_under_two_minutes_is_still_one_minute() {
            let backup = backup_at(2024, 6, 15, 10, 30, 0);
            let now = datetime(2024, 6, 15, 10, 31, 59);

            assert_eq!(backup.age(now), "1 minute");
        }

        #[test]
        fn two_minutes_uses_plural() {
            let backup = backup_at(2024, 6, 15, 10, 30, 0);
            let now = datetime(2024, 6, 15, 10, 32, 0);

            assert_eq!(backup.age(now), "2 minutes");
        }

        #[test]
        fn fifty_nine_minutes_before_hour_threshold() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 15, 10, 59, 59);

            assert_eq!(backup.age(now), "59 minutes");
        }

        #[test]
        fn exactly_one_hour() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 15, 11, 0, 0);

            assert_eq!(backup.age(now), "1 hour");
        }

        #[test]
        fn just_under_two_hours_is_still_one_hour() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 15, 11, 59, 59);

            assert_eq!(backup.age(now), "1 hour");
        }

        #[test]
        fn two_hours_uses_plural() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 15, 12, 0, 0);

            assert_eq!(backup.age(now), "2 hours");
        }

        #[test]
        fn twenty_three_hours_before_day_threshold() {
            let backup = backup_at(2024, 6, 15, 0, 0, 0);
            let now = datetime(2024, 6, 15, 23, 59, 59);

            assert_eq!(backup.age(now), "23 hours");
        }

        #[test]
        fn exactly_one_day() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 16, 10, 0, 0);

            assert_eq!(backup.age(now), "1 day");
        }

        #[test]
        fn six_days_before_week_threshold() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 21, 9, 59, 59);

            assert_eq!(backup.age(now), "5 days");
        }

        #[test]
        fn exactly_one_week() {
            let backup = backup_at(2024, 6, 15, 10, 0, 0);
            let now = datetime(2024, 6, 22, 10, 0, 0);

            assert_eq!(backup.age(now), "1 week");
        }

        #[test]
        fn two_weeks() {
            let backup = backup_at(2024, 6, 1, 10, 0, 0);
            let now = datetime(2024, 6, 15, 10, 0, 0);

            assert_eq!(backup.age(now), "2 weeks");
        }

        #[test]
        fn three_weeks_exactly() {
            let backup = backup_at(2024, 6, 1, 10, 0, 0);
            let now = datetime(2024, 6, 22, 10, 0, 0); // exactly 21 days = 3 weeks

            assert_eq!(backup.age(now), "3 weeks");
        }

        #[test]
        fn just_under_four_weeks_still_shows_weeks() {
            let backup = backup_at(2024, 6, 1, 10, 0, 0);
            let now = datetime(2024, 6, 29, 9, 59, 59); // just under 28 days

            assert_eq!(backup.age(now), "3 weeks");
        }

        #[test]
        fn exactly_one_month_four_weeks() {
            let backup = backup_at(2024, 6, 1, 10, 0, 0);
            let now = datetime(2024, 6, 29, 10, 0, 0);

            // 4 weeks = 28 days, which is the "month" threshold in this implementation
            assert_eq!(backup.age(now), "1 month");
        }

        #[test]
        fn two_months() {
            let backup = backup_at(2024, 1, 1, 10, 0, 0);
            let now = datetime(2024, 3, 1, 10, 0, 0);

            // ~60 days = 2 "months" (8 weeks)
            assert_eq!(backup.age(now), "2 months");
        }

        #[test]
        fn many_months_ago() {
            let backup = backup_at(2024, 1, 1, 0, 0, 0);
            let now = datetime(2024, 12, 1, 0, 0, 0);

            // ~11 months = roughly 48 weeks
            let age = backup.age(now);
            assert!(age.ends_with("months"), "Expected months, got: {age}");
        }
    }

    mod backup_status_display {
        use super::*;

        #[test]
        fn retainable_is_padded_to_12_chars() {
            let status = BackupStatus::Retainable;
            assert_eq!(format!("{status}"), "retainable  ");
        }

        #[test]
        fn purgeable_is_padded_to_12_chars() {
            let status = BackupStatus::Purgeable;
            assert_eq!(format!("{status}"), "purgeable   ");
        }
    }

    mod backup_equality {
        use super::*;

        #[test]
        fn same_path_and_date_are_equal() {
            let a = backup_at(2024, 6, 15, 10, 30, 0);
            let b = backup_at(2024, 6, 15, 10, 30, 0);

            assert_eq!(a, b);
        }

        #[test]
        fn different_dates_are_not_equal() {
            let a = backup_at(2024, 6, 15, 10, 30, 0);
            let b = backup_at(2024, 6, 15, 10, 30, 1);

            assert_ne!(a, b);
        }

        #[test]
        fn different_paths_are_not_equal() {
            let a = Backup {
                filepath: PathBuf::from("/tmp/a.tar.zst"),
                creation_date: datetime(2024, 6, 15, 10, 30, 0),
            };
            let b = Backup {
                filepath: PathBuf::from("/tmp/b.tar.zst"),
                creation_date: datetime(2024, 6, 15, 10, 30, 0),
            };

            assert_ne!(a, b);
        }
    }
}