use std::fmt;
use std::ffi::CString;
use std::path::PathBuf;
use std::mem;
use std::ptr;

use mongo_c_driver_wrapper::bindings;

use bson::Document;

use super::Result;
use super::BsoncError;
use super::bsonc::Bsonc;
use super::collection::{Collection,CreatedBy};
use super::database::Database;
use super::uri::Uri;
use super::read_prefs::ReadPrefs;

// TODO: We're using a sort of poor man's Arc here
// with this root bool, there must be a better way.
pub struct ClientPool {
    root_instance: bool,
    uri:           Uri,
    inner:         *mut bindings::mongoc_client_pool_t
}

impl ClientPool {
    /// Create a new ClientPool with optionally SSL options
    ///
    /// See: http://api.mongodb.org/c/current/mongoc_client_pool_t.html
    /// And: http://api.mongodb.org/c/current/mongoc_ssl_opt_t.html
    pub fn new(uri: Uri, ssl_options: Option<SslOptions>) -> ClientPool {
        super::init();
        let pool = unsafe {
            let pool_ptr = bindings::mongoc_client_pool_new(uri.inner());
            assert!(!pool_ptr.is_null());
            pool_ptr
        };
        match ssl_options {
            Some(options) => {
                unsafe {
                    bindings::mongoc_client_pool_set_ssl_opts(
                        pool,
                        options.inner()
                    );
                }
            },
            None => ()
        };
        ClientPool {
            root_instance: true,
            uri:           uri, // Become owner of uri so it doesn't go out of scope
            inner:         pool
        }
    }

    /// Retrieve a client from the client pool, possibly blocking until one is available.
    /// See: http://api.mongodb.org/c/current/mongoc_client_pool_pop.html
    pub fn pop(&self) -> Client {
        assert!(!self.inner.is_null());
        let client = unsafe { bindings::mongoc_client_pool_pop(self.inner) };
        Client{
            client_pool: self,
            inner:       client
        }
    }

    /// Return a client back to the client pool, called from drop of client.
    /// See: http://api.mongodb.org/c/current/mongoc_client_pool_push.html
    unsafe fn push(&self, mongo_client: *mut bindings::mongoc_client_t) {
        assert!(!self.inner.is_null());
        bindings::mongoc_client_pool_push(
            self.inner,
            mongo_client
        );
    }
}

unsafe impl Send for ClientPool { }
unsafe impl Sync for ClientPool { }

impl fmt::Debug for ClientPool {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "ClientPool for {}", self.uri.as_str())
    }
}

impl Clone for ClientPool {
    fn clone(&self) -> ClientPool {
        assert!(!self.inner.is_null());
        ClientPool {
            root_instance: false,
            uri:           self.uri.clone(),
            inner:         self.inner.clone()
        }
    }
}

impl Drop for ClientPool {
    fn drop(&mut self) {
        if self.root_instance {
            assert!(!self.inner.is_null());
            unsafe {
                bindings::mongoc_client_pool_destroy(self.inner);
            }
        }
    }
}

pub struct SslOptions {
    inner:                bindings::mongoc_ssl_opt_t,
    pem_file:             Option<PathBuf>,
    pem_password:         Option<String>,
    ca_file:              Option<PathBuf>,
    ca_dir:               Option<PathBuf>,
    crl_file:             Option<PathBuf>,
    weak_cert_validation: bool
}

impl SslOptions {
    pub fn new(
        pem_file:             Option<PathBuf>,
        pem_password:         Option<String>,
        ca_file:              Option<PathBuf>,
        ca_dir:               Option<PathBuf>,
        crl_file:             Option<PathBuf>,
        weak_cert_validation: bool
    ) -> SslOptions {
        let ssl_options = bindings::mongoc_ssl_opt_t {
            pem_file: match pem_file {
                Some(ref f) => Self::path_ptr(f),
                None    => ptr::null()
            },
            pem_pwd: match pem_password {
                Some(ref password) => CString::new(password.clone()).unwrap().as_ptr(),
                None => ptr::null()
            },
            ca_file: match ca_file {
                Some(ref f) => Self::path_ptr(f),
                None    => ptr::null()
            },
            ca_dir: match ca_dir {
                Some(ref f) => Self::path_ptr(f),
                None    => ptr::null()
            },
            crl_file: match crl_file {
                Some(ref f) => Self::path_ptr(f),
                None    => ptr::null()
            },
            weak_cert_validation: weak_cert_validation as u8,
            padding:              unsafe { mem::uninitialized() }
        };

        SslOptions {
            inner:                ssl_options,
            pem_file:             pem_file,
            pem_password:         pem_password,
            ca_file:              ca_file,
            ca_dir:               ca_dir,
            crl_file:             crl_file,
            weak_cert_validation: weak_cert_validation
        }
    }

    fn path_ptr(path: &PathBuf) -> *const i8 {
        path.as_os_str().to_cstring().unwrap().as_ptr()
    }

    fn inner(&self) -> *const bindings::mongoc_ssl_opt_t {
        &self.inner
    }
}

impl Clone for SslOptions {
    fn clone(&self) -> SslOptions {
        SslOptions::new(
            self.pem_file.clone(),
            self.pem_password.clone(),
            self.ca_file.clone(),
            self.ca_dir.clone(),
            self.crl_file.clone(),
            self.weak_cert_validation
        )
    }
}

pub struct Client<'a> {
    client_pool: &'a ClientPool,
    inner:       *mut bindings::mongoc_client_t
}

impl<'a> Client<'a> {
    pub fn get_collection<S: Into<Vec<u8>>>(&'a self, db: S, collection: S) -> Collection<'a> {
        assert!(!self.inner.is_null());
        let coll = unsafe {
            let db_cstring         = CString::new(db).unwrap();
            let collection_cstring = CString::new(collection).unwrap();
            bindings::mongoc_client_get_collection(
                self.inner,
                db_cstring.as_ptr(),
                collection_cstring.as_ptr()
            )
        };
        Collection::new(CreatedBy::Client(self), coll)
    }

    pub fn get_database<S: Into<Vec<u8>>>(&'a self, db: S) -> Database<'a> {
        assert!(!self.inner.is_null());
        let coll = unsafe {
            let db_cstring = CString::new(db).unwrap();
            bindings::mongoc_client_get_database(
                self.inner,
                db_cstring.as_ptr()
            )
        };
        Database::new(self, coll)
    }

    /// Queries the server for the current server status.
    ///
    /// See: http://api.mongodb.org/c/current/mongoc_client_get_server_status.html
    pub fn get_server_status(&self, read_prefs: Option<ReadPrefs>) -> Result<Document> {
        assert!(!self.inner.is_null());

        // Bsonc to store the reply
        let mut reply = Bsonc::new();
        // Empty error that might be filled
        let mut error = BsoncError::empty();

        let success = unsafe {
            bindings::mongoc_client_get_server_status(
                self.inner,
                match read_prefs {
                    Some(ref prefs) => prefs.mut_inner(),
                    None => ptr::null_mut()
                },
                reply.mut_inner(),
                error.mut_inner()
            )
        };

        if success == 1 {
            match reply.as_document() {
                Ok(document) => return Ok(document),
                Err(error)   => return Err(error.into())
            }
        } else {
            Err(error.into())
        }
    }
}

impl<'a> Drop for Client<'a> {
    fn drop(&mut self) {
        assert!(!self.inner.is_null());
        unsafe {
            self.client_pool.push(self.inner);
        }
    }
}

#[cfg(test)]
mod tests {
    use std::path::PathBuf;
    use std::thread;
    use super::super::uri::Uri;
    use super::{ClientPool,SslOptions};

    #[test]
    fn test_new_pool_and_pop_client() {
        let uri = Uri::new("mongodb://localhost:27017/");
        let pool = ClientPool::new(uri, None);

        // Pop a client and get a database and collection
        let client = pool.pop();
        pool.pop();

        let database = client.get_database("rust_test");
        assert_eq!("rust_test", database.get_name().to_mut());

        let collection = client.get_collection("rust_test", "items");
        assert_eq!("items", collection.get_name().to_mut());
    }

    #[test]
    fn test_new_pool_and_pop_client_in_threads() {
        let uri = Uri::new("mongodb://localhost:27017/");
        let pool = ClientPool::new(uri, None);

        let pool1 = pool.clone();
        let guard1 = thread::spawn(move || {
            let client = pool1.pop();
            client.get_collection("test", "items");
        });

        let pool2 = pool.clone();
        let guard2 = thread::spawn(move || {
            let client = pool2.pop();
            client.get_collection("test", "items");
        });

        guard1.join().unwrap();
        guard2.join().unwrap();
    }

    #[test]
    fn test_get_server_status() {
        let uri = Uri::new("mongodb://localhost:27017/");
        let pool = ClientPool::new(uri, None);
        let client = pool.pop();

        let status = client.get_server_status(None).unwrap();

        assert!(status.contains_key("host"));
        assert!(status.contains_key("version"));
    }

    #[test]
    fn test_new_pool_with_ssl_options() {
        // We currently have no way to test full operations
        let uri = Uri::new("mongodb://localhost:27017/");
        let ssl_options = SslOptions::new(
            Some(PathBuf::from("/tmp/pem_file")),
            Some("password".to_string()),
            Some(PathBuf::from("/tmp/ca_file")),
            Some(PathBuf::from("/tmp/ca_dir")),
            Some(PathBuf::from("/tmp/crl_file")),
            false
        );
        ClientPool::new(uri, Some(ssl_options));
    }
}