// This file is part of bsv.
//
// bsv 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.
//
// bsv 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 Affero General Public License for
// more details.
//
// You should have received a copy of the Affero GNU General Public License
// along with bsv.  If not, see <https://www.gnu.org/licenses/>.


use camino::{Utf8Path, Utf8PathBuf};
use toml::{Value, Table};

use cas_core::{err, Error, Result};


#[derive(Debug, Clone)]
pub struct PathPair {
    pub logic: Utf8PathBuf,
    pub physic: Utf8PathBuf,
}

impl PathPair {
    pub fn new(logic: Utf8PathBuf, physic: Utf8PathBuf) -> Self {
        Self { logic, physic }
    }

    pub fn physic_from_logic<P: AsRef<Utf8Path>>(&self, logic_path: P) -> Result<Utf8PathBuf> {
        let mut physic = self.physic.clone();
        physic.push(
            logic_path.as_ref().strip_prefix(&self.logic)?
        );

        Ok(physic)
    }

    pub fn logic_from_physic<P: AsRef<Utf8Path>>(&self, physic_path: P) -> Result<Utf8PathBuf> {
        let mut logic = self.logic.clone();
        logic.push(
            physic_path.as_ref().strip_prefix(&self.physic)?
        );

        Ok(logic)
    }
}


#[derive(Clone, Debug)]
pub struct PathMap {
    pairs: Vec<PathPair>,
    logic_order: Vec<usize>,
    physic_order: Vec<usize>,
}


impl PathMap {
    pub fn new() -> PathMap {
        PathMap {
            pairs: vec![],
            logic_order: vec![],
            physic_order: vec![],
        }
    }

    pub fn from_vec(vec: Vec<PathPair>) -> Result<Self> {
        if let Some(pair) =
            vec.iter()
                .filter(|p| !p.logic.is_absolute())
                .next() {
            return err!("relative logic path: {}", pair.logic);
        }

        let mut logic_order: Vec<_> = (0..vec.len()).collect();
        logic_order.sort_by(|&i0, &i1| vec[i0].logic.cmp(&vec[i1].logic).reverse());

        if let Some((&index, _)) =
            logic_order[..logic_order.len()-1].iter()
                .zip(logic_order[1..].iter())
                .filter(|(&i0, &i1)| vec[i0].logic == vec[i1].logic)
                .next() {
            return err!("duplicate logic path: {:?}", vec[index]);
        }

        let mut physic_order: Vec<_> = (0..vec.len()).collect();
        physic_order.sort_by(|&i0, &i1| vec[i0].physic.cmp(&vec[i1].physic).reverse());

        if let Some((&index, _)) =
            physic_order[..physic_order.len()-1].iter()
                .zip(physic_order[1..].iter())
                .filter(|(&i0, &i1)| vec[i0].physic == vec[i1].physic)
                .next() {
            return err!("duplicate physic path: {:?}", vec[index]);
        }

        Ok(Self {
            pairs: vec,
            logic_order,
            physic_order,
        })
    }

    pub fn from_toml_value(config: &Value) -> Result<Self> {
        let map = if let Some(mapping) = config.get("mapping") {
            if let Some(ref table) = mapping.as_table() {
                table.iter()
                    .map(|(k, v)| Ok(PathPair{
                        logic: k.into(),
                        physic: Utf8PathBuf::from_path_buf(
                            Utf8Path::new(
                                v.as_str()
                                    .ok_or_else(|| Error::unknown("mapping values must be strings"))?
                            ).canonicalize()?
                        ).or_else(|e| err!("non-unicode character in path: {:?}", e))?
                    }))
                    .collect::<Result<_>>()?
            }
            else {
                err!("mapping must be a table, got {}", mapping)?
            }
        }
        else {
            vec![]
        };

        Self::from_vec(map)
    }

    pub fn to_toml_value(&self) -> Result<Value> {
        let mut table = Table::new();
        for pair in self.pairs.iter() {
            table[pair.logic.as_str()] = pair.physic.as_str().into();
        }
        Ok(Value::Table(table))
    }

    pub fn path_pair_from_logic<P: AsRef<Utf8Path>>(&self, logic_path: P) -> Option<&PathPair> {
        let path = logic_path.as_ref();

        Some(self.logic_order.iter()
            .map(|&i| &self.pairs[i])
            .filter(|p| path.starts_with(&p.logic))
            .next()?
        )
    }

    pub fn path_pair_from_physic<P: AsRef<Utf8Path>>(&self, physic_path: P) -> Option<&PathPair> {
        let path = physic_path.as_ref();

        Some(self.physic_order.iter()
            .map(|&i| &self.pairs[i])
            .filter(|p| path.starts_with(&p.physic))
            .next()?
        )
    }

    pub fn physic_from_logic<P: AsRef<Utf8Path>>(&self, logic_path: P) -> Option<Utf8PathBuf> {
        self.path_pair_from_logic(&logic_path)?
            .physic_from_logic(&logic_path).ok()
    }

    pub fn logic_from_physic<P: AsRef<Utf8Path>>(&self, physic_path: P) -> Option<Utf8PathBuf> {
        self.path_pair_from_physic(&physic_path)?
            .logic_from_physic(&physic_path).ok()
    }
}



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

    #[test]
    fn test_path_map() {
        let path_map = PathMap::from_vec(vec![
            PathPair::new("/foo/bar".into(), "/home/user/bar".into()),
        ]).unwrap();

        assert_eq!(
            path_map.physic_from_logic("/bar"),
            None,
        );
        assert_eq!(
            path_map.physic_from_logic("/foo/bar"),
            Some("/home/user/bar".into()),
        );
        assert_eq!(
            path_map.physic_from_logic("/foo/bar/file.txt"),
            Some("/home/user/bar/file.txt".into()),
        );

        assert_eq!(
            path_map.logic_from_physic("/home/user"),
            None,
        );
        assert_eq!(
            path_map.logic_from_physic("/home/user/bar"),
            Some("/foo/bar".into()),
        );
        assert_eq!(
            path_map.logic_from_physic("/home/user/bar/file.txt"),
            Some("/foo/bar/file.txt".into()),
        );
    }

    #[test]
    fn test_path_map_subdirs() {
        let path_map = PathMap::from_vec(vec![
            PathPair::new("/foo/bar/baz".into(), "/home/user/bar/test".into()),
            PathPair::new("/foo/bar".into(), "/home/user/bar".into()),
        ]).unwrap();

        assert_eq!(
            path_map.physic_from_logic("/foo/bar/file.txt"),
            Some("/home/user/bar/file.txt".into()),
        );
        assert_eq!(
            path_map.physic_from_logic("/foo/bar/baz/file.txt"),
            Some("/home/user/bar/test/file.txt".into()),
        );

        assert_eq!(
            path_map.logic_from_physic("/home/user/bar/file.txt"),
            Some("/foo/bar/file.txt".into()),
        );
        assert_eq!(
            path_map.logic_from_physic("/home/user/bar/test/file.txt"),
            Some("/foo/bar/baz/file.txt".into()),
        );
    }

    #[test]
    fn test_path_map_crossed_subdirs() {
        let path_map = PathMap::from_vec(vec![
            PathPair::new("/foo/bar/baz".into(), "/home/user/bar".into()),
            PathPair::new("/foo/bar".into(), "/home/user/bar/test".into()),
        ]).unwrap();

        assert_eq!(
            path_map.physic_from_logic("/foo/bar/baz/file.txt"),
            Some("/home/user/bar/file.txt".into()),
        );
        assert_eq!(
            path_map.physic_from_logic("/foo/bar/file.txt"),
            Some("/home/user/bar/test/file.txt".into()),
        );

        assert_eq!(
            path_map.logic_from_physic("/home/user/bar/test/file.txt"),
            Some("/foo/bar/file.txt".into()),
        );
        assert_eq!(
            path_map.logic_from_physic("/home/user/bar/file.txt"),
            Some("/foo/bar/baz/file.txt".into()),
        );
    }


    #[test]
    fn test_path_fail_on_duplicates() {
        PathMap::from_vec(vec![
            PathPair::new("/foo/bar".into(), "/home/user/bar".into()),
            PathPair::new("/foo/bar".into(), "/home/user/bar/test".into()),
        ]).expect_err("should fail on duplicate logic path");

        PathMap::from_vec(vec![
            PathPair::new("/foo/bar/baz".into(), "/home/user/bar".into()),
            PathPair::new("/foo/bar".into(), "/home/user/bar".into()),
        ]).expect_err("should fail on duplicate physic path");
    }
}