/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
use std::borrow::ToOwned;
use std::collections::BTreeMap;
use std::collections::HashMap;
use std::sync::mpsc::channel;
use url::Url;

use net_traits::storage_task::{StorageTask, StorageTaskMsg, StorageType};
use util::str::DOMString;
use util::task::spawn_named;

pub trait StorageTaskFactory {
    fn new() -> Self;
}

impl StorageTaskFactory for StorageTask {
    /// Create a StorageTask
    fn new() -> StorageTask {
        let (chan, port) = ipc::channel().unwrap();
        spawn_named("StorageManager".to_owned(), move || {
            StorageManager::new(port).start();
        });
        chan
    }
}

struct StorageManager {
    port: IpcReceiver<StorageTaskMsg>,
    session_data: HashMap<String, BTreeMap<DOMString, DOMString>>,
    local_data: HashMap<String, BTreeMap<DOMString, DOMString>>,
}

impl StorageManager {
    fn new(port: IpcReceiver<StorageTaskMsg>) -> StorageManager {
        StorageManager {
            port: port,
            session_data: HashMap::new(),
            local_data: HashMap::new(),
        }
    }
}

impl StorageManager {
    fn start(&mut self) {
        loop {
            match self.port.recv().unwrap() {
                StorageTaskMsg::Length(sender, url, storage_type) => {
                    self.length(sender, url, storage_type)
                }
                StorageTaskMsg::Key(sender, url, storage_type, index) => {
                    self.key(sender, url, storage_type, index)
                }
                StorageTaskMsg::SetItem(sender, url, storage_type, name, value) => {
                    self.set_item(sender, url, storage_type, name, value)
                }
                StorageTaskMsg::GetItem(sender, url, storage_type, name) => {
                    self.request_item(sender, url, storage_type, name)
                }
                StorageTaskMsg::RemoveItem(sender, url, storage_type, name) => {
                    self.remove_item(sender, url, storage_type, name)
                }
                StorageTaskMsg::Clear(sender, url, storage_type) => {
                    self.clear(sender, url, storage_type)
                }
                StorageTaskMsg::Exit => {
                    break
                }
            }
        }
    }

    fn select_data(&self, storage_type: StorageType)
                   -> &HashMap<String, BTreeMap<DOMString, DOMString>> {
        match storage_type {
            StorageType::Session => &self.session_data,
            StorageType::Local => &self.local_data
        }
    }

    fn select_data_mut(&mut self, storage_type: StorageType)
                       -> &mut HashMap<String, BTreeMap<DOMString, DOMString>> {
        match storage_type {
            StorageType::Session => &mut self.session_data,
            StorageType::Local => &mut self.local_data
        }
    }

    fn length(&self, sender: IpcSender<usize>, url: Url, storage_type: StorageType) {
        let origin = self.origin_as_string(url);
        let data = self.select_data(storage_type);
        sender.send(data.get(&origin).map_or(0, |entry| entry.len())).unwrap();
    }

    fn key(&self,
           sender: IpcSender<Option<DOMString>>,
           url: Url,
           storage_type: StorageType,
           index: u32) {
        let origin = self.origin_as_string(url);
        let data = self.select_data(storage_type);
        sender.send(data.get(&origin)
                    .and_then(|entry| entry.keys().nth(index as usize))
                    .map(|key| key.clone())).unwrap();
    }

    /// Sends Some(old_value) in case there was a previous value with the same key name but with different
    /// value name, otherwise sends None
    fn set_item(&mut self,
                sender: IpcSender<(bool, Option<DOMString>)>,
                url: Url,
                storage_type: StorageType,
                name: DOMString,
                value: DOMString) {
        let origin = self.origin_as_string(url);
        let data = self.select_data_mut(storage_type);
        if !data.contains_key(&origin) {
            data.insert(origin.clone(), BTreeMap::new());
        }

        let (changed, old_value) = data.get_mut(&origin).map(|entry| {
            entry.insert(name, value.clone()).map_or(
                (true, None),
                |old| if old == value {
                    (false, None)
                } else {
                    (true, Some(old))
                })
        }).unwrap();
        sender.send((changed, old_value)).unwrap();
    }

    fn request_item(&self,
                sender: IpcSender<Option<DOMString>>,
                url: Url,
                storage_type: StorageType,
                name: DOMString) {
        let origin = self.origin_as_string(url);
        let data = self.select_data(storage_type);
        sender.send(data.get(&origin)
                    .and_then(|entry| entry.get(&name))
                    .map(|value| value.to_string())).unwrap();
    }

    /// Sends Some(old_value) in case there was a previous value with the key name, otherwise sends None
    fn remove_item(&mut self,
                   sender: IpcSender<Option<DOMString>>,
                   url: Url,
                   storage_type: StorageType,
                   name: DOMString) {
        let origin = self.origin_as_string(url);
        let data = self.select_data_mut(storage_type);
        let old_value = data.get_mut(&origin).and_then(|entry| {
            entry.remove(&name)
        });
        sender.send(old_value).unwrap();
    }

    fn clear(&mut self, sender: IpcSender<bool>, url: Url, storage_type: StorageType) {
        let origin = self.origin_as_string(url);
        let data = self.select_data_mut(storage_type);
        sender.send(data.get_mut(&origin)
                    .map_or(false, |entry| {
                        if !entry.is_empty() {
                            entry.clear();
                            true
                        } else {
                            false
                        }})).unwrap();
    }

    fn origin_as_string(&self, url: Url) -> String {
        let mut origin = "".to_string();
        origin.push_str(&url.scheme);
        origin.push_str("://");
        url.domain().map(|domain| origin.push_str(&domain));
        url.port().map(|port| {
            origin.push_str(":");
            origin.push_str(&port.to_string());
        });
        origin.push_str("/");
        origin
    }
}