use std::path::Path;
use std::{fs, io};

use crate::error::BakareError;
use crate::index::{Index, IndexIterator, ItemVersion};
use crate::repository_item::RepositoryItem;
use sha2::Digest;
use sha2::Sha512;
use std::fs::File;
use std::io::BufReader;

/// represents a place where backup is stored an can be restored from.
/// right now only on-disk directory storage is supported
/// repository always knows the newest version of the index and is responsible for syncing the index to disk
/// and making sure that different threads can access index in parallel
pub struct Repository<'a> {
    /// absolute path to where the repository is stored on disk
    path: &'a Path,
    index: Index,
}

pub struct RepositoryIterator<'a> {
    index_iterator: IndexIterator<'a>,
}

impl<'a> Iterator for RepositoryIterator<'a> {
    type Item = RepositoryItem;

    fn next(&mut self) -> Option<Self::Item> {
        self.index_iterator.next()
    }
}

impl<'a> Repository<'a> {
    pub fn init(path: &Path) -> Result<(), BakareError> {
        let index = Index::new(path);
        index.save()?;
        Ok(())
    }

    pub fn open(path: &Path) -> Result<Repository, BakareError> {
        if !path.is_absolute() {
            return Err(BakareError::RepositoryPathNotAbsolute);
        }

        let index = Index::load(path)?;
        Ok(Repository { path, index })
    }

    pub fn iter(&self) -> RepositoryIterator {
        RepositoryIterator {
            index_iterator: self.index.iter(),
        }
    }

    pub fn store(&mut self, source_path: &Path) -> Result<(), BakareError> {
        if !source_path.is_absolute() {
            return Err(BakareError::PathToStoreNotAbsolute);
        }
        let destination_path: &str = &(self.path.to_string_lossy() + source_path.to_string_lossy());
        let destination_path = Path::new(&destination_path);
        if source_path == destination_path {
            return Err(BakareError::SourceSameAsRepository);
        }
        if source_path.is_dir() {
            fs::create_dir(destination_path)?;
        }

        if source_path.is_file() {
            fs::create_dir_all(destination_path.parent().unwrap())?;
            let version = Repository::calculate_version(source_path)?;
            fs::copy(source_path, destination_path)?;

            self.index.remember(RepositoryItem::from(
                source_path,
                destination_path,
                destination_path.strip_prefix(self.path)?,
                version,
            ));
            self.index.save()?;
        }
        Ok(())
    }

    fn calculate_version(source_path: &Path) -> Result<ItemVersion, BakareError> {
        let source_file = File::open(source_path)?;
        let mut reader = BufReader::new(source_file);
        let mut hasher = Sha512::new();

        io::copy(&mut reader, &mut hasher)?;

        Ok(hasher.result().as_slice().into())
    }

    pub fn item_by_source_path(&self, path: &Path) -> Result<Option<RepositoryItem>, BakareError> {
        if !path.is_absolute() {
            return Err(BakareError::RepositoryPathNotAbsolute);
        }
        Ok(self.iter().find(|i| i.original_source_path() == path))
    }
}