/* 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/. */

//! The high-level interface from script to constellation. Using this abstract interface helps
//! reduce coupling between these two components.

use std::cell::Cell;
use std::fmt;
use std::num::NonZeroU32;

#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
pub enum TraversalDirection {
    Forward(usize),
    Back(usize),
}

/// Each pipeline ID needs to be unique. However, it also needs to be possible to
/// generate the pipeline ID from an iframe element (this simplifies a lot of other
/// code that makes use of pipeline IDs).
///
/// To achieve this, each pipeline index belongs to a particular namespace. There is
/// a namespace for the constellation thread, and also one for every script thread.
/// This allows pipeline IDs to be generated by any of those threads without conflicting
/// with pipeline IDs created by other script threads or the constellation. The
/// constellation is the only code that is responsible for creating new *namespaces*.
/// This ensures that namespaces are always unique, even when using multi-process mode.
///
/// It may help conceptually to think of the namespace ID as an identifier for the
/// thread that created this pipeline ID - however this is really an implementation
/// detail so shouldn't be relied upon in code logic. It's best to think of the
/// pipeline ID as a simple unique identifier that doesn't convey any more information.
#[derive(Clone, Copy)]
pub struct PipelineNamespace {
    id: PipelineNamespaceId,
    index: u32,
}

impl PipelineNamespace {
    pub fn install(namespace_id: PipelineNamespaceId) {
        PIPELINE_NAMESPACE.with(|tls| {
            assert!(tls.get().is_none());
            tls.set(Some(PipelineNamespace {
                id: namespace_id,
                index: 0,
            }));
        });
    }

    fn next_index(&mut self) -> NonZeroU32 {
        self.index += 1;
        NonZeroU32::new(self.index).expect("pipeline id index wrapped!")
    }

    fn next_pipeline_id(&mut self) -> PipelineId {
        PipelineId {
            namespace_id: self.id,
            index: PipelineIndex(self.next_index()),
        }
    }

    fn next_browsing_context_id(&mut self) -> BrowsingContextId {
        BrowsingContextId {
            namespace_id: self.id,
            index: BrowsingContextIndex(self.next_index()),
        }
    }

    fn next_history_state_id(&mut self) -> HistoryStateId {
        HistoryStateId {
            namespace_id: self.id,
            index: HistoryStateIndex(self.next_index()),
        }
    }
}

thread_local!(pub static PIPELINE_NAMESPACE: Cell<Option<PipelineNamespace>> = Cell::new(None));

#[derive(
    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
)]
pub struct PipelineNamespaceId(pub u32);

#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
pub struct PipelineIndex(pub NonZeroU32);
malloc_size_of_is_0!(PipelineIndex);

#[derive(
    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
)]
pub struct PipelineId {
    pub namespace_id: PipelineNamespaceId,
    pub index: PipelineIndex,
}

impl PipelineId {
    pub fn new() -> PipelineId {
        PIPELINE_NAMESPACE.with(|tls| {
            let mut namespace = tls.get().expect("No namespace set for this thread!");
            let new_pipeline_id = namespace.next_pipeline_id();
            tls.set(Some(namespace));
            new_pipeline_id
        })
    }

    pub fn to_webrender(&self) -> webrender_api::PipelineId {
        let PipelineNamespaceId(namespace_id) = self.namespace_id;
        let PipelineIndex(index) = self.index;
        webrender_api::PipelineId(namespace_id, index.get())
    }

    #[allow(unsafe_code)]
    pub fn from_webrender(pipeline: webrender_api::PipelineId) -> PipelineId {
        let webrender_api::PipelineId(namespace_id, index) = pipeline;
        unsafe {
            PipelineId {
                namespace_id: PipelineNamespaceId(namespace_id),
                index: PipelineIndex(NonZeroU32::new_unchecked(index)),
            }
        }
    }

    pub fn root_scroll_node(&self) -> webrender_api::ClipId {
        webrender_api::ClipId::root_scroll_node(self.to_webrender())
    }

    pub fn root_scroll_id(&self) -> webrender_api::ExternalScrollId {
        webrender_api::ExternalScrollId(0, self.to_webrender())
    }

    pub fn root_clip_and_scroll_info(&self) -> webrender_api::ClipAndScrollInfo {
        webrender_api::ClipAndScrollInfo::simple(self.root_scroll_node())
    }
}

impl fmt::Display for PipelineId {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        let PipelineNamespaceId(namespace_id) = self.namespace_id;
        let PipelineIndex(index) = self.index;
        write!(fmt, "({},{})", namespace_id, index.get())
    }
}

#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
pub struct BrowsingContextIndex(pub NonZeroU32);
malloc_size_of_is_0!(BrowsingContextIndex);

#[derive(
    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
)]
pub struct BrowsingContextId {
    pub namespace_id: PipelineNamespaceId,
    pub index: BrowsingContextIndex,
}

impl BrowsingContextId {
    pub fn new() -> BrowsingContextId {
        PIPELINE_NAMESPACE.with(|tls| {
            let mut namespace = tls.get().expect("No namespace set for this thread!");
            let new_browsing_context_id = namespace.next_browsing_context_id();
            tls.set(Some(namespace));
            new_browsing_context_id
        })
    }
}

impl fmt::Display for BrowsingContextId {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        let PipelineNamespaceId(namespace_id) = self.namespace_id;
        let BrowsingContextIndex(index) = self.index;
        write!(fmt, "({},{})", namespace_id, index.get())
    }
}

thread_local!(pub static TOP_LEVEL_BROWSING_CONTEXT_ID: Cell<Option<TopLevelBrowsingContextId>> = Cell::new(None));

#[derive(
    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
)]
pub struct TopLevelBrowsingContextId(BrowsingContextId);

impl TopLevelBrowsingContextId {
    pub fn new() -> TopLevelBrowsingContextId {
        TopLevelBrowsingContextId(BrowsingContextId::new())
    }
    /// Each script and layout thread should have the top-level browsing context id installed,
    /// since it is used by crash reporting.
    pub fn install(id: TopLevelBrowsingContextId) {
        TOP_LEVEL_BROWSING_CONTEXT_ID.with(|tls| tls.set(Some(id)))
    }

    pub fn installed() -> Option<TopLevelBrowsingContextId> {
        TOP_LEVEL_BROWSING_CONTEXT_ID.with(|tls| tls.get())
    }
}

impl fmt::Display for TopLevelBrowsingContextId {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(fmt)
    }
}

impl From<TopLevelBrowsingContextId> for BrowsingContextId {
    fn from(id: TopLevelBrowsingContextId) -> BrowsingContextId {
        id.0
    }
}

impl PartialEq<TopLevelBrowsingContextId> for BrowsingContextId {
    fn eq(&self, rhs: &TopLevelBrowsingContextId) -> bool {
        self.eq(&rhs.0)
    }
}

impl PartialEq<BrowsingContextId> for TopLevelBrowsingContextId {
    fn eq(&self, rhs: &BrowsingContextId) -> bool {
        self.0.eq(rhs)
    }
}

#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
pub struct HistoryStateIndex(pub NonZeroU32);
malloc_size_of_is_0!(HistoryStateIndex);

#[derive(
    Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, Ord, PartialEq, PartialOrd, Serialize,
)]
pub struct HistoryStateId {
    pub namespace_id: PipelineNamespaceId,
    pub index: HistoryStateIndex,
}

impl HistoryStateId {
    pub fn new() -> HistoryStateId {
        PIPELINE_NAMESPACE.with(|tls| {
            let mut namespace = tls.get().expect("No namespace set for this thread!");
            let next_history_state_id = namespace.next_history_state_id();
            tls.set(Some(namespace));
            next_history_state_id
        })
    }
}

impl fmt::Display for HistoryStateId {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        let PipelineNamespaceId(namespace_id) = self.namespace_id;
        let HistoryStateIndex(index) = self.index;
        write!(fmt, "({},{})", namespace_id, index.get())
    }
}

// We provide ids just for unit testing.
pub const TEST_NAMESPACE: PipelineNamespaceId = PipelineNamespaceId(1234);
#[allow(unsafe_code)]
pub const TEST_PIPELINE_INDEX: PipelineIndex =
    unsafe { PipelineIndex(NonZeroU32::new_unchecked(5678)) };
pub const TEST_PIPELINE_ID: PipelineId = PipelineId {
    namespace_id: TEST_NAMESPACE,
    index: TEST_PIPELINE_INDEX,
};
#[allow(unsafe_code)]
pub const TEST_BROWSING_CONTEXT_INDEX: BrowsingContextIndex =
    unsafe { BrowsingContextIndex(NonZeroU32::new_unchecked(8765)) };
pub const TEST_BROWSING_CONTEXT_ID: BrowsingContextId = BrowsingContextId {
    namespace_id: TEST_NAMESPACE,
    index: TEST_BROWSING_CONTEXT_INDEX,
};

// Used to specify the kind of input method editor appropriate to edit a field.
// This is a subset of htmlinputelement::InputType because some variants of InputType
// don't make sense in this context.
#[derive(Debug, Deserialize, Serialize)]
pub enum InputMethodType {
    Color,
    Date,
    DatetimeLocal,
    Email,
    Month,
    Number,
    Password,
    Search,
    Tel,
    Text,
    Time,
    Url,
    Week,
}