use std::error::Error;
use std::fmt::Display;
use std::fmt::Formatter;
use std::fmt::Error as FmtError;
use std::clone::Clone;

/**
 * Kind of store error
 */
#[derive(Clone, Copy, Debug)]
pub enum StoreErrorKind {
    FileError,
    IdLocked,
    IdNotFound,
    OutOfMemory,
    FileNotFound,
    FileNotCreated,
    // maybe more
}

fn store_error_type_as_str(e: &StoreErrorKind) -> &'static str {
    match e {
        &StoreErrorKind::FileError   => "File Error",
        &StoreErrorKind::IdLocked    => "ID locked",
        &StoreErrorKind::IdNotFound  => "ID not found",
        &StoreErrorKind::OutOfMemory => "Out of Memory",
        &StoreErrorKind::FileNotFound => "File corresponding to ID not found",
        &StoreErrorKind::FileNotCreated => "File corresponding to ID could not be created",
    }
}

impl Display for StoreErrorKind {

    fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
        try!(write!(fmt, "{}", store_error_type_as_str(self)));
        Ok(())
    }

}

/**
 * Store error type
 */
#[derive(Debug)]
pub struct StoreError {
    err_type: StoreErrorKind,
    cause: Option<Box<Error>>,
}

impl StoreError {

    /**
     * Build a new StoreError from an StoreErrorKind, optionally with cause
     */
    pub fn new(errtype: StoreErrorKind, cause: Option<Box<Error>>)
        -> StoreError
    {
        StoreError {
            err_type: errtype,
            cause: cause,
        }
    }

    /**
     * Get the error type of this StoreError
     */
    pub fn err_type(&self) -> StoreErrorKind {
        self.err_type.clone()
    }

}

impl Display for StoreError {

    fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
        try!(write!(fmt, "[{}]", store_error_type_as_str(&self.err_type.clone())));
        Ok(())
    }

}

impl Error for StoreError {

    fn description(&self) -> &str {
        store_error_type_as_str(&self.err_type.clone())
    }

    fn cause(&self) -> Option<&Error> {
        self.cause.as_ref().map(|e| &**e)
    }

}