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//  ------------------------------------------------------------------
//  Airone
//  is a Rust library which provides a simple in-memory,
//  write-on-update database that is persisted
//  to an append-only transaction file.
//
//  Copyright © 2022 Massimo Gismondi
//
//  This file is part of Airone.
//  Airone is free software: you can redistribute it and/or
//  modify it under the terms of the GNU Affero General Public License
//  as published by the Free Software Foundation, either version 3
//  of the License, or (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
//  GNU General Public License for more details.

//  You should have received a copy of the GNU Affero General Public License
//  along with this program. If not, see <https://www.gnu.org/licenses/>.
//  ------------------------------------------------------------------

/// A value that can be converted to a String
/// properly escaping characters that are not
/// allowed in airone's CSV format
///
/// Sometimes it's enough to format!() the value,
/// sometimes it needs custom conversions.
pub trait PersistableValue
{
    fn to_persistable_string(&self) -> String;
}

/// A value that can be converted from the String
/// to its actual type.
///
/// Sometimes it's enough to parse the value,
/// sometimes it needs custom conversions.
pub trait LoadableValue
{
    fn from_persistable_string(s: &String) -> Self;
}

macro_rules! impl_persistable_value_with_format {
    ($($t:ty),*) => {
        $(
            impl PersistableValue for $t
            {

                fn to_persistable_string(&self) -> String
                {
                    format!("{}", &self)
                }
            }
        )*
    };
}
impl_persistable_value_with_format!(
    bool, i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize, f32, f64
);

macro_rules! impl_loadable_value_with_parse {
    ($($t:ty),*) => {
        $(
            impl LoadableValue for $t
            {
                fn from_persistable_string(s: &String) -> $t
                {
                    return (s.parse::<$t>().unwrap()).clone()
                }
            }
        )*
    };
}
impl_loadable_value_with_parse!(
    bool, i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize, f32, f64
);

impl PersistableValue for String
{
    fn to_persistable_string(&self) -> String
    {
        let a = &self.clone();
        return a
            .replace("\n", "\\n")
            .replace("\r", "\\r")
            .replace("\t", "\\t")
            .replace("\"", "\\\"");
    }
}
impl LoadableValue for String
{
    fn from_persistable_string(s: &String) -> String
    {
        let a = s.clone();
        return a
            .replace("\\n", "\n")
            .replace("\\r", "\r")
            .replace("\\t", "\t")
            .replace("\\\"", "\"");
    }
}

impl<T> PersistableValue for Option<T>
where
    T: PersistableValue
{
    fn to_persistable_string(&self) -> String
    {
        if let Some(el) = &self
        {
            return el.to_persistable_string();
        }
        else
        {
            return String::new();
        }
    }
}

impl<A: LoadableValue> LoadableValue for Option<A>
{
    fn from_persistable_string(s: &String) -> Option<A>
    {
        if s.len() > 0
        {
            let b: A = LoadableValue::from_persistable_string(s);
            return Some(b);
        }
        else
        {
            return None;
        }
    }
}