use std::fmt::{Display, Formatter};
use std::convert::From;
use std::str::Utf8Error;

use sqlx::{
    error::Error as SqlxError,
    migrate::MigrateError,
};


// error during initial setup (primarily loading state from db)
pub enum SetupError {
    InvalidRecord, // e.g. wrong size blob for nonce or salt
    DbError(SqlxError),
}
impl From<SqlxError> for SetupError {
    fn from(e: SqlxError) -> SetupError {
        SetupError::DbError(e)
    }
}
impl From<MigrateError> for SetupError {
    fn from (e: MigrateError) -> SetupError {
        SetupError::DbError(SqlxError::from(e))
    }
}
impl Display for SetupError {
    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {
        match self {
            SetupError::InvalidRecord => write!(f, "Malformed database record"),
            SetupError::DbError(e) => write!(f, "Error from database: {e}"),
        }
    }
}


// error when attempting to tell a request handler whether to release or deny crednetials
pub enum SendResponseError {
    NotFound, // no request with the given id
    Abandoned, // request has already been closed by client
}

impl Display for SendResponseError {
    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {
        use SendResponseError::*;
        match self {
            NotFound => write!(f, "The specified command was not found."),
            Abandoned => write!(f, "The specified request was closed by the client."),
        }
    }
}


// errors encountered while handling an HTTP request
pub enum RequestError {
    StreamIOError(std::io::Error),
    InvalidUtf8,
    MalformedHttpRequest,
    RequestTooLarge,
    NoCredentials(GetCredentialsError),
    ClientInfo(ClientInfoError),
}
impl From<tokio::io::Error> for RequestError {
    fn from(e: std::io::Error) -> RequestError {
        RequestError::StreamIOError(e)
    }
}
impl From<Utf8Error> for RequestError {
    fn from(_e: Utf8Error) -> RequestError {
        RequestError::InvalidUtf8
    }
}
impl From<GetCredentialsError> for RequestError {
    fn from (e: GetCredentialsError) -> RequestError {
        RequestError::NoCredentials(e)
    }
}
impl From<ClientInfoError> for RequestError {
    fn from(e: ClientInfoError) -> RequestError {
        RequestError::ClientInfo(e)
    }
}

impl Display for RequestError {
    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {
        use RequestError::*;
        match self {
            StreamIOError(e) => write!(f, "Stream IO error: {e}"),
            InvalidUtf8 => write!(f, "Could not decode UTF-8 from bytestream"),
            MalformedHttpRequest => write!(f, "Maformed HTTP request"),
            RequestTooLarge => write!(f, "HTTP request too large"),
            NoCredentials(GetCredentialsError::Locked) => write!(f, "Recieved go-ahead but app is locked"),
            NoCredentials(GetCredentialsError::Empty) => write!(f, "Received go-ahead but no credentials are known"),
            ClientInfo(ClientInfoError::PidNotFound) => write!(f, "Could not resolve PID of client process."),
            ClientInfo(ClientInfoError::NetstatError(e)) => write!(f, "Error getting client socket details: {e}"),
        }
    }
}


pub enum GetCredentialsError {
    Locked,
    Empty,
}


pub enum UnlockError {
    NotLocked,
    NoCredentials,
    BadPassphrase,
    InvalidUtf8, // Somehow we got invalid utf-8 even though decryption succeeded
    DbError(SqlxError),
}
impl From<SqlxError> for UnlockError {
    fn from (e: SqlxError) -> UnlockError {
        match e {
            SqlxError::RowNotFound => UnlockError::NoCredentials,
            _ => UnlockError::DbError(e),
        }
    }
}
impl Display for UnlockError {
    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {
        use UnlockError::*;
        match self {
            NotLocked => write!(f, "App is not locked"),
            NoCredentials => write!(f, "No saved credentials were found"),
            BadPassphrase => write!(f, "Invalid passphrase"),
            InvalidUtf8 => write!(f, "Decrypted data was corrupted"),
            DbError(e) => write!(f, "Database error: {e}"),
        }
    }
}


// Errors encountered while trying to figure out who's on the other end of a request
pub enum ClientInfoError {
    PidNotFound,
    NetstatError(netstat2::error::Error),
}
impl From<netstat2::error::Error> for ClientInfoError {
    fn from(e: netstat2::error::Error) -> ClientInfoError {
        ClientInfoError::NetstatError(e)
    }
}