use std::fs::File;
use std::io::{Read, Seek, Write};
use std::path::PathBuf;

#[derive(serde::Serialize, serde::Deserialize, Debug, Clone)]
pub struct TrashFile {
    pub name: String,
    pub origin: PathBuf,
}

pub struct Manifest {
    files: Vec<TrashFile>,
    manifest: File,
}

impl Manifest {
    /// Creates a new Manifest from a .manifest.ron file.
    /// Expects File to be read and write.
    pub fn new(mut manifest: File) -> Result<Self, TrashManifestError> {
        let mut contents = String::new();
        manifest.read_to_string(&mut contents)?;
        manifest.rewind()?;

        if contents.len() < 2 {
            contents = "[]".to_string();
        }
        let files: Vec<TrashFile> = ron::from_str(&contents)?;
        Ok(Self { files, manifest })
    }

    /// Get a certain file from the manifest by it's name.
    pub fn get(&self, name: String) -> Option<TrashFile> {
        self.files
            .iter()
            .find(|file| file.name == *name)
            .map(|file| file.clone())
    }

    /// Get a clone of the underlying Vec of TrashFile.
    pub fn get_all(&self) -> Vec<TrashFile> {
        self.files.clone()
    }

    /// Remove a file from the manifest by it's name.
    /// Consumes self and returns self back in a result to prevent inconsistencies
    /// between self and the actual manifest file in case of Err.
    pub fn remove(mut self, name: String) -> Result<Self, TrashManifestError> {
        self.files.retain(|file| file.name != name);
        let contents = ron::to_string(&self.files)?;
        self.manifest.set_len(0)?;
        self.manifest.rewind()?;
        write!(&mut self.manifest, "{}", contents)?;
        Ok(self)
    }

    /// Add a file to the manifest by it's name and path to origin.
    /// Consumes self and returns self back in a result to prevent inconsistencies
    /// between self and the actual manifest file in case of Err.
    pub fn add(mut self, name: String, origin: PathBuf) -> Result<Self, TrashManifestError> {
        self.files.push(TrashFile { name, origin });
        dbg!(&self.files);
        let contents = ron::to_string(&self.files)?;
        self.manifest.set_len(0)?;
        self.manifest.rewind()?;
        write!(&mut self.manifest, "{}", contents)?;
        Ok(self)
    }
}

#[derive(thiserror::Error, Debug)]
pub enum TrashManifestError {
    #[error("Could not read manifest file")]
    IoError(#[from] std::io::Error),
    #[error("Could not serialize or deserialize manifest file")]
    SerializationError(#[from] ron::Error),
}