use std::libc::c_int;
use std::ptr;
use std::str;
use std::vec;

mod ffi {
    use std::libc::{c_char, c_int, c_void};
    use std::cast;

    pub type sqlite3 = c_void;
    pub type sqlite3_stmt = c_void;

    pub static SQLITE_OK: c_int = 0;
    pub static SQLITE_ROW: c_int = 100;
    pub static SQLITE_DONE: c_int = 101;

    pub static SQLITE_NULL: c_int = 5;

    // A function because Rust doesn't like casting from an int to a function
    // pointer in a static declaration
    pub fn SQLITE_TRANSIENT() -> extern "C" fn(*c_void) {
        unsafe { cast::transmute(-1) }
    }

    #[link_args = "-lsqlite3"]
    extern "C" {
        fn sqlite3_open(filename: *c_char, ppDb: *mut *sqlite3) -> c_int;
        fn sqlite3_close(db: *sqlite3) -> c_int;
        fn sqlite3_errmsg(db: *sqlite3) -> *c_char;
        fn sqlite3_changes(db: *sqlite3) -> c_int;
        fn sqlite3_prepare_v2(db: *sqlite3, zSql: *c_char, nByte: c_int,
                              ppStmt: *mut *sqlite3_stmt, pzTail: *mut *c_char)
                              -> c_int;
        fn sqlite3_reset(pStmt: *sqlite3_stmt) -> c_int;
        fn sqlite3_bind_text(pStmt: *sqlite3_stmt, idx: c_int, text: *c_char,
                             n: c_int, free: extern "C" fn(*c_void)) -> c_int;
        fn sqlite3_bind_null(pStmt: *sqlite3_stmt, idx: c_int) -> c_int;
        fn sqlite3_step(pStmt: *sqlite3_stmt) -> c_int;
        fn sqlite3_column_count(pStmt: *sqlite3_stmt) -> c_int;
        fn sqlite3_column_type(pStmt: *sqlite3_stmt, iCol: c_int) -> c_int;
        fn sqlite3_column_text(pStmt: *sqlite3_stmt, iCol: c_int) -> *c_char;
        fn sqlite3_finalize(pStmt: *sqlite3_stmt) -> c_int;
    }
}

pub fn open(filename: &str) -> Result<~Connection, ~str> {
    let mut conn = ~Connection {conn: ptr::null()};
    let ret = do filename.as_c_str |c_filename| {
        unsafe { ffi::sqlite3_open(c_filename, &mut conn.conn) }
    };

    match ret {
        ffi::SQLITE_OK => Ok(conn),
        _ => Err(conn.get_error())
    }
}

pub struct Connection {
    priv conn: *ffi::sqlite3
}

impl Drop for Connection {
    fn drop(&self) {
        unsafe { ffi::sqlite3_close(self.conn) };
    }
}

impl Connection {
    fn get_error(&self) -> ~str {
        unsafe {
            str::raw::from_c_str(ffi::sqlite3_errmsg(self.conn))
        }
    }
}

macro_rules! ret_err(
    ($mat:expr { $($p:pat => $blk:expr),+ }) => (
        match $mat {
            Err(err) => return Err(err),
            $(
                $p => $blk,
            )+
        }
    );

    ($mat:expr) => (
        match $mat {
            Err(err) => return Err(err),
            _ => ()
        }
    )
)

impl Connection {
    pub fn prepare<'a>(&'a self, query: &str)
                       -> Result<~PreparedStatement<'a>, ~str> {
        let mut stmt = ~PreparedStatement {conn: self, stmt: ptr::null()};
        let ret = do query.as_c_str |c_query| {
            unsafe {
                ffi::sqlite3_prepare_v2(self.conn, c_query, -1, &mut stmt.stmt,
                                        ptr::mut_null())
            }
        };

        match ret {
            ffi::SQLITE_OK => Ok(stmt),
            _ => Err(self.get_error())
        }
    }

    pub fn update(&self, query: &str) -> Result<uint, ~str> {
        self.update_params(query, [])
    }

    pub fn update_params(&self, query: &str, params: &[@SqlType])
                         -> Result<uint, ~str> {
        self.prepare(query).chain(|stmt| stmt.update_params(params))
    }

    pub fn query<T>(&self, query: &str, blk: &fn (&mut ResultIterator) -> T)
                    -> Result<T, ~str> {
        self.query_params(query, [], blk)
    }

    pub fn query_params<T>(&self, query: &str, params: &[@SqlType],
                           blk: &fn (&mut ResultIterator) -> T)
                           -> Result<T, ~str> {
        let stmt = ret_err!(self.prepare(query) { Ok(stmt) => stmt });
        let mut it = ret_err!(stmt.query_params(params) { Ok(it) => it });
        Ok(blk(&mut it))
    }

    pub fn in_transaction<T>(&self, blk: &fn(&Connection) -> Result<T, ~str>)
                             -> Result<T, ~str> {
        ret_err!(self.update("BEGIN"));

        let ret = blk(self);

        // TODO: What to do with errors here?
        match ret {
            Ok(_) => self.update("COMMIT"),
            Err(_) => self.update("ROLLBACK")
        };

        ret
    }
}

pub struct PreparedStatement<'self> {
    priv conn: &'self Connection,
    priv stmt: *ffi::sqlite3_stmt
}

#[unsafe_destructor]
impl<'self> Drop for PreparedStatement<'self> {
    fn drop(&self) {
        unsafe { ffi::sqlite3_finalize(self.stmt); }
    }
}

impl<'self> PreparedStatement<'self> {
    fn reset(&self) {
        unsafe { ffi::sqlite3_reset(self.stmt); }
    }

    fn bind_params(&self, params: &[@SqlType]) -> Result<(), ~str> {
        for (idx, param) in params.iter().enumerate() {
            let ret = match param.to_sql_str() {
                Some(val) => do val.as_c_str |c_param| {
                    unsafe {
                        ffi::sqlite3_bind_text(self.stmt, (idx+1) as c_int,
                                               c_param, -1,
                                               ffi::SQLITE_TRANSIENT())
                    }
                },
                None => unsafe {
                    ffi::sqlite3_bind_null(self.stmt, (idx+1) as c_int)
                }
            };

            if ret != ffi::SQLITE_OK {
                return Err(self.conn.get_error());
            }
        }

        Ok(())
    }
}

impl<'self> PreparedStatement<'self> {

    pub fn update(&self) -> Result<uint, ~str> {
        self.update_params([])
    }

    pub fn update_params(&self, params: &[@SqlType]) -> Result<uint, ~str> {
        self.reset();
        ret_err!(self.bind_params(params));

        let ret = unsafe { ffi::sqlite3_step(self.stmt) };

        match ret {
            // TODO: Should we consider a query that returned rows an error?
            ffi::SQLITE_DONE | ffi::SQLITE_ROW =>
                Ok(unsafe { ffi::sqlite3_changes(self.conn.conn) } as uint),
            _ => Err(self.conn.get_error())
        }
    }

    pub fn query(&'self self) -> Result<ResultIterator<'self>, ~str> {
        self.query_params([])
    }

    pub fn query_params(&'self self, params: &[@SqlType])
            -> Result<ResultIterator<'self>, ~str> {
        self.reset();
        ret_err!(self.bind_params(params));
        Ok(ResultIterator {stmt: self})
    }
}

pub struct ResultIterator<'self> {
    priv stmt: &'self PreparedStatement<'self>
}

impl<'self> Iterator<Row<'self>> for ResultIterator<'self> {
    fn next(&mut self) -> Option<Row<'self>> {
        let ret = unsafe { ffi::sqlite3_step(self.stmt.stmt) };
        match ret {
            ffi::SQLITE_ROW => Some(Row::new(self.stmt)),
            // TODO: Ignoring errors for now
            _ => None
        }
    }
}

pub struct Row<'self> {
    // Only here to enforce lifetime restrictions
    priv stmt: &'self PreparedStatement<'self>,
    priv cols: ~[Option<~str>]
}

impl<'self> Row<'self> {
    fn new(stmt: &'self PreparedStatement<'self>) -> Row<'self> {
        let count = unsafe { ffi::sqlite3_column_count(stmt.stmt) as uint};
        let mut row = Row {stmt: stmt, cols: vec::with_capacity(count)};

        for i in range(0, count) {
            let typ = unsafe {
                ffi::sqlite3_column_type(stmt.stmt, i as c_int)
            };
            let val = match typ {
                ffi::SQLITE_NULL => None,
                _ => Some(unsafe {
                    str::raw::from_c_str(ffi::sqlite3_column_text(stmt.stmt,
                                                                  i as c_int))
                })
            };
            row.cols.push(val);
        }

        return row
    }
}

impl<'self> Row<'self> {
    pub fn get<T: SqlType>(&self, idx: uint) -> T {
        SqlType::from_sql_str(&self.cols[idx])
    }
}

impl<'self> Container for Row<'self> {
    fn len(&self) -> uint {
        self.cols.len()
    }
}

impl<'self, T: SqlType> Index<uint, T> for Row<'self> {
    fn index(&self, idx: &uint) -> T {
        self.get(*idx)
    }
}

pub trait SqlType {
    fn to_sql_str(&self) -> Option<~str>;
    fn from_sql_str(sql_str: &Option<~str>) -> Self;
}

// See #8075
macro_rules! to_from_str_impl(
    ($t:ty) => (
        impl SqlType for $t {
            fn to_sql_str(&self) -> Option<~str> {
                Some(self.to_str())
            }

            fn from_sql_str(sql_str: &Option<~str>) -> $t {
                FromStr::from_str(*sql_str.get_ref()).get()
            }
        }
    )
)

macro_rules! option_impl(
    ($t:ty) => (
        impl SqlType for Option<$t> {
            fn to_sql_str(&self) -> Option<~str> {
                match *self {
                    None => None,
                    Some(ref v) => Some(v.to_sql_str().get())
                }
            }

            fn from_sql_str(sql_str: &Option<~str>) -> Option<$t> {
                match *sql_str {
                    None => None,
                    Some(_) => Some(SqlType::from_sql_str(sql_str))
                }
            }
        }
    )
)

to_from_str_impl!(int)
option_impl!(int)
to_from_str_impl!(i8)
option_impl!(i8)
to_from_str_impl!(i16)
option_impl!(i16)
to_from_str_impl!(i32)
option_impl!(i32)
to_from_str_impl!(i64)
option_impl!(i64)
to_from_str_impl!(uint)
option_impl!(uint)
to_from_str_impl!(u8)
option_impl!(u8)
to_from_str_impl!(u16)
option_impl!(u16)
to_from_str_impl!(u32)
option_impl!(u32)
to_from_str_impl!(u64)
option_impl!(u64)
to_from_str_impl!(float)
option_impl!(float)
to_from_str_impl!(f32)
option_impl!(f32)
to_from_str_impl!(f64)
option_impl!(f64)

impl SqlType for ~str {
    fn to_sql_str(&self) -> Option<~str> {
        Some(self.clone())
    }

    fn from_sql_str(sql_str: &Option<~str>) -> ~str {
        sql_str.get_ref().clone()
    }
}
option_impl!(~str)