use byteorder;
use phf;
use std::error;
use std::convert::From;
use std::fmt;
use std::io;
use std::result;
use std::collections::HashMap;

use {Result, DbErrorNew};
use types::Type;

include!(concat!(env!("OUT_DIR"), "/sqlstate.rs"));

/// A Postgres error or notice.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct DbError {
    severity: String,
    code: SqlState,
    message: String,
    detail: Option<String>,
    hint: Option<String>,
    position: Option<ErrorPosition>,
    where_: Option<String>,
    schema: Option<String>,
    table: Option<String>,
    column: Option<String>,
    datatype: Option<String>,
    constraint: Option<String>,
    file: String,
    line: u32,
    routine: String,
}

impl DbErrorNew for DbError {
    fn new_raw(fields: Vec<(u8, String)>) -> result::Result<DbError, ()> {
        let mut map: HashMap<_, _> = fields.into_iter().collect();
        Ok(DbError {
            severity: try!(map.remove(&b'S').ok_or(())),
            code: SqlState::from_code(try!(map.remove(&b'C').ok_or(()))),
            message: try!(map.remove(&b'M').ok_or(())),
            detail: map.remove(&b'D'),
            hint: map.remove(&b'H'),
            position: match map.remove(&b'P') {
                Some(pos) => Some(ErrorPosition::Normal(try!(pos.parse().map_err(|_| ())))),
                None => match map.remove(&b'p') {
                    Some(pos) => Some(ErrorPosition::Internal {
                        position: try!(pos.parse().map_err(|_| ())),
                        query: try!(map.remove(&b'q').ok_or(()))
                    }),
                    None => None
                }
            },
            where_: map.remove(&b'W'),
            schema: map.remove(&b's'),
            table: map.remove(&b't'),
            column: map.remove(&b'c'),
            datatype: map.remove(&b'd'),
            constraint: map.remove(&b'n'),
            file: try!(map.remove(&b'F').ok_or(())),
            line: try!(map.remove(&b'L').and_then(|l| l.parse().ok()).ok_or(())),
            routine: try!(map.remove(&b'R').ok_or(())),
        })
    }

    fn new_connect<T>(fields: Vec<(u8, String)>) -> result::Result<T, ConnectError> {
        match DbError::new_raw(fields) {
            Ok(err) => Err(ConnectError::DbError(err)),
            Err(()) => Err(ConnectError::IoError(::bad_response())),
        }
    }

    fn new<T>(fields: Vec<(u8, String)>) -> Result<T> {
        match DbError::new_raw(fields) {
            Ok(err) => Err(Error::DbError(err)),
            Err(()) => Err(Error::IoError(::bad_response())),
        }
    }
}

impl DbError {
    /// The field contents are ERROR, FATAL, or PANIC (in an error message),
    /// or WARNING, NOTICE, DEBUG, INFO, or LOG (in a notice message), or a
    /// localized translation of one of these.
    pub fn severity(&self) -> &str {
        &self.severity
    }

    /// The SQLSTATE code for the error.
    pub fn code(&self) -> &SqlState {
        &self.code
    }

    /// The primary human-readable error message. This should be accurate but
    /// terse (typically one line).
    pub fn message(&self) -> &str {
        &self.message
    }

    /// An optional secondary error message carrying more detail about the
    /// problem. Might run to multiple lines.
    pub fn detail(&self) -> Option<&str> {
        self.detail.as_ref().map(|s| &**s)
    }

    /// An optional suggestion what to do about the problem. This is intended
    /// to differ from Detail in that it offers advice (potentially
    /// inappropriate) rather than hard facts. Might run to multiple lines.
    pub fn hint(&self) -> Option<&str> {
        self.hint.as_ref().map(|s| &**s)
    }

    /// An optional error cursor position into either the original query string
    /// or an internally generated query.
    pub fn position(&self) -> Option<&ErrorPosition> {
        self.position.as_ref()
    }

    /// An indication of the context in which the error occurred. Presently
    /// this includes a call stack traceback of active procedural language
    /// functions and internally-generated queries. The trace is one entry per
    /// line, most recent first.
    pub fn where_(&self) -> Option<&str> {
        self.where_.as_ref().map(|s| &**s)
    }

    /// If the error was associated with a specific database object, the name
    /// of the schema containing that object, if any. (PostgreSQL 9.3+)
    pub fn schema(&self) -> Option<&str> {
        self.schema.as_ref().map(|s| &**s)
    }

    /// If the error was associated with a specific table, the name of the
    /// table. (Refer to the schema name field for the name of the table's
    /// schema.) (PostgreSQL 9.3+)
    pub fn table(&self) -> Option<&str> {
        self.table.as_ref().map(|s| &**s)
    }

    /// If the error was associated with a specific table column, the name of
    /// the column. (Refer to the schema and table name fields to identify the
    /// table.) (PostgreSQL 9.3+)
    pub fn column(&self) -> Option<&str> {
        self.column.as_ref().map(|s| &**s)
    }

    /// If the error was associated with a specific data type, the name of the
    /// data type. (Refer to the schema name field for the name of the data
    /// type's schema.) (PostgreSQL 9.3+)
    pub fn datatype(&self) -> Option<&str> {
        self.datatype.as_ref().map(|s| &**s)
    }

    /// If the error was associated with a specific constraint, the name of the
    /// constraint. Refer to fields listed above for the associated table or
    /// domain. (For this purpose, indexes are treated as constraints, even if
    /// they weren't created with constraint syntax.) (PostgreSQL 9.3+)
    pub fn constraint(&self) -> Option<&str> {
        self.constraint.as_ref().map(|s| &**s)
    }

    /// The file name of the source-code location where the error was reported.
    pub fn file(&self) -> &str {
        &self.file
    }

    /// The line number of the source-code location where the error was
    /// reported.
    pub fn line(&self) -> u32 {
        self.line
    }

    /// The name of the source-code routine reporting the error.
    pub fn routine(&self) -> &str {
        &self.routine
    }
}

impl fmt::Display for DbError {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        write!(fmt, "{}: {}", self.severity, self.message)
    }
}

impl error::Error for DbError {
    fn description(&self) -> &str {
        &self.message
    }
}

/// Reasons a new Postgres connection could fail.
#[derive(Debug)]
pub enum ConnectError {
    /// The provided URL could not be parsed.
    InvalidUrl(String),
    /// The URL was missing a user.
    MissingUser,
    /// An error from the Postgres server itself.
    DbError(DbError),
    /// A password was required but not provided in the URL.
    MissingPassword,
    /// The Postgres server requested an authentication method not supported
    /// by the driver.
    UnsupportedAuthentication,
    /// The Postgres server does not support SSL encryption.
    NoSslSupport,
    /// There was an error initializing the SSL session
    SslError(Box<error::Error+Sync+Send>),
    /// There was an error communicating with the server.
    IoError(io::Error),
}

impl fmt::Display for ConnectError {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        try!(fmt.write_str(error::Error::description(self)));
        match *self {
            ConnectError::InvalidUrl(ref msg) => write!(fmt, ": {}", msg),
            _ => Ok(())
        }
    }
}

impl error::Error for ConnectError {
    fn description(&self) -> &str {
        match *self {
            ConnectError::InvalidUrl(_) => "Invalid URL",
            ConnectError::MissingUser => "User missing in URL",
            ConnectError::DbError(_) => "An error from the Postgres server itself",
            ConnectError::MissingPassword => "The server requested a password but none was provided",
            ConnectError::UnsupportedAuthentication => {
                "The server requested an unsupported authentication method"
            }
            ConnectError::NoSslSupport => "The server does not support SSL",
            ConnectError::SslError(_) => "Error initiating SSL session",
            ConnectError::IoError(_) => "Error communicating with server",
        }
    }

    fn cause(&self) -> Option<&error::Error> {
        match *self {
            ConnectError::DbError(ref err) => Some(err),
            ConnectError::SslError(ref err) => Some(&**err),
            ConnectError::IoError(ref err) => Some(err),
            _ => None
        }
    }
}

impl From<io::Error> for ConnectError {
    fn from(err: io::Error) -> ConnectError {
        ConnectError::IoError(err)
    }
}

impl From<DbError> for ConnectError {
    fn from(err: DbError) -> ConnectError {
        ConnectError::DbError(err)
    }
}

impl From<byteorder::Error> for ConnectError {
    fn from(err: byteorder::Error) -> ConnectError {
        ConnectError::IoError(From::from(err))
    }
}

/// Represents the position of an error in a query.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum ErrorPosition {
    /// A position in the original query.
    Normal(u32),
    /// A position in an internally generated query.
    Internal {
        /// The byte position.
        position: u32,
        /// A query generated by the Postgres server.
        query: String
    }
}

/// An error encountered when communicating with the Postgres server.
#[derive(Debug)]
pub enum Error {
    /// An error reported by the Postgres server.
    DbError(DbError),
    /// An error communicating with the Postgres server.
    IoError(io::Error),
    /// The communication channel with the Postgres server has desynchronized
    /// due to an earlier communications error.
    StreamDesynchronized,
    /// An attempt was made to convert between incompatible Rust and Postgres
    /// types.
    WrongType(Type),
    /// An attempt was made to read from a column that does not exist.
    InvalidColumn,
    /// An error converting between Postgres and Rust types.
    Conversion(Box<error::Error+Sync+Send>),
}

impl fmt::Display for Error {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        try!(fmt.write_str(error::Error::description(self)));
        match *self {
            Error::WrongType(ref ty) => write!(fmt, ": saw type {:?}", ty),
            _ => Ok(()),
        }
    }
}

impl error::Error for Error {
    fn description(&self) -> &str {
        match *self {
            Error::DbError(_) => "An error reported by the Postgres server",
            Error::IoError(_) => "An error communicating with the Postgres server",
            Error::StreamDesynchronized => {
                "Communication with the server has desynchronized due to an earlier IO error"
            }
            Error::WrongType(_) => "Unexpected type",
            Error::InvalidColumn => "Invalid column",
            Error::Conversion(_) => "An error converting between Postgres and Rust types",
        }
    }

    fn cause(&self) -> Option<&error::Error> {
        match *self {
            Error::DbError(ref err) => Some(err),
            Error::IoError(ref err) => Some(err),
            Error::Conversion(ref err) => Some(&**err),
            _ => None
        }
    }
}

impl From<DbError> for Error {
    fn from(err: DbError) -> Error {
        Error::DbError(err)
    }
}

impl From<io::Error> for Error {
    fn from(err: io::Error) -> Error {
        Error::IoError(err)
    }
}

impl From<byteorder::Error> for Error {
    fn from(err: byteorder::Error) -> Error {
        Error::IoError(From::from(err))
    }
}