/// Represents database driver that can be shared between threads, and can therefore implement
/// a connection pool
pub trait Driver: Sync + Send {
    /// Create a connection to the database. Note that connections are intended to be used
    /// in a single thread since most database connections are not thread-safe
    fn connect(&self, url: &str) -> Result<Box<dyn Connection>>;
}

/// Represents a connection to a database
pub trait Connection {
    /// Create a statement for execution
    fn create(&mut self, sql: &str) -> Result<Box<dyn Statement + '_>>;

    /// Create a prepared statement for execution
    fn prepare(&mut self, sql: &str) -> Result<Box<dyn Statement + '_>>;
}

/// Represents an executable statement
pub trait Statement {
    /// Execute a query that is expected to return a result set, such as a `SELECT` statement
    fn execute_query(&mut self, params: &[Value]) -> Result<Box<dyn ResultSet + '_>>;

    /// Execute a query that is expected to update some rows.
    fn execute_update(&mut self, params: &[Value]) -> Result<u64>;
}

/// Result set from executing a query against a statement
pub trait ResultSet {
    /// get meta data about this result set
    fn meta_data(&self) -> Result<Box<dyn ResultSetMetaData>>;

    /// Move the cursor to the next available row if one exists and return true if it does
    fn next(&mut self) -> bool;

    fn get_i8(&self, i: u64) -> Result<Option<i8>>;
    fn get_i16(&self, i: u64) -> Result<Option<i16>>;
    fn get_i32(&self, i: u64) -> Result<Option<i32>>;
    fn get_i64(&self, i: u64) -> Result<Option<i64>>;
    fn get_f32(&self, i: u64) -> Result<Option<f32>>;
    fn get_f64(&self, i: u64) -> Result<Option<f64>>;
    fn get_string(&self, i: u64) -> Result<Option<String>>;
    fn get_bytes(&self, i: u64) -> Result<Option<Vec<u8>>>;

    // NOTE that only a subset of data types are supported so far in this PoC
    // and accessors need to be added for other types such as date and time
}

/// Meta data for result set
pub trait ResultSetMetaData {
    fn num_columns(&self) -> u64;
    fn column_name(&self, i: usize) -> String;
    fn column_type(&self, i: usize) -> DataType;
}

let driver: Arc<dyn rdbc::Driver> = Arc::new(PostgresDriver::new());
let mut conn = driver.connect("postgres:https://user:[email protected]:5433")?;
let mut stmt = conn.prepare("SELECT a FROM test")?;
let mut rs = stmt.execute_query(&vec![])?;
while rs.next() {
  println!("{:?}", rs.get_string(1)?);
}