/* 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 https://mozilla.org/MPL/2.0/. */

//! before-change style: the `@starting-style` rules.
//! https://drafts.csswg.org/css-transitions-2/#defining-before-change-style

use crate::shared_lock::{DeepCloneParams, DeepCloneWithLock, Locked};
use crate::shared_lock::{SharedRwLock, SharedRwLockReadGuard, ToCssWithGuard};
use crate::str::CssStringWriter;
use crate::stylesheets::CssRules;
use cssparser::SourceLocation;
use malloc_size_of::{MallocSizeOfOps, MallocUnconditionalShallowSizeOf};
use servo_arc::Arc;
use std::fmt::{self, Debug, Write};

/// A [`@starting-style`][starting-style] rule.
///
/// [starting-style]: https://drafts.csswg.org/css-transitions-2/#at-ruledef-starting-style
#[derive(Debug, ToShmem)]
pub struct StartingStyleRule {
    /// The nested rules to this starting-style rule.
    pub rules: Arc<Locked<CssRules>>,
    /// The source position where this starting-style rule was found.
    pub source_location: SourceLocation,
}

impl StartingStyleRule {
    /// Measure heap usage.
    #[cfg(feature = "gecko")]
    pub fn size_of(&self, guard: &SharedRwLockReadGuard, ops: &mut MallocSizeOfOps) -> usize {
        self.rules.unconditional_shallow_size_of(ops) +
            self.rules.read_with(guard).size_of(guard, ops)
    }
}

impl ToCssWithGuard for StartingStyleRule {
    fn to_css(&self, guard: &SharedRwLockReadGuard, dest: &mut CssStringWriter) -> fmt::Result {
        dest.write_str("@starting-style")?;
        self.rules.read_with(guard).to_css_block(guard, dest)
    }
}

impl DeepCloneWithLock for StartingStyleRule {
    fn deep_clone_with_lock(
        &self,
        lock: &SharedRwLock,
        guard: &SharedRwLockReadGuard,
        params: &DeepCloneParams,
    ) -> Self {
        let rules = self.rules.read_with(guard);
        StartingStyleRule {
            rules: Arc::new(lock.wrap(rules.deep_clone_with_lock(lock, guard, params))),
            source_location: self.source_location.clone(),
        }
    }
}