/* 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/. */

//! Common handling for the specified value CSS url() values.

use cssparser::Parser;
use gecko_bindings::bindings;
use gecko_bindings::structs::{ServoBundledURI, URLExtraData};
use gecko_bindings::structs::mozilla::css::URLValueData;
use gecko_bindings::structs::root::{RustString, nsStyleImageRequest};
use gecko_bindings::structs::root::mozilla::css::{ImageValue, URLValue};
use gecko_bindings::sugar::refptr::RefPtr;
use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
use parser::{Parse, ParserContext};
use servo_arc::{Arc, RawOffsetArc};
use std::mem;
use style_traits::ParseError;

/// A CSS url() value for gecko.
#[css(function = "url")]
#[derive(Clone, Debug, PartialEq, ToCss)]
pub struct CssUrl {
    /// The URL in unresolved string form.
    ///
    /// Refcounted since cloning this should be cheap and data: uris can be
    /// really large.
    serialization: Arc<String>,

    /// The URL extra data.
    #[css(skip)]
    pub extra_data: RefPtr<URLExtraData>,
}

impl CssUrl {
    /// Try to parse a URL from a string value that is a valid CSS token for a
    /// URL.
    ///
    /// Returns `Err` in the case that extra_data is incomplete.
    pub fn parse_from_string<'a>(
        url: String,
        context: &ParserContext,
    ) -> Result<Self, ParseError<'a>> {
        Ok(CssUrl {
            serialization: Arc::new(url),
            extra_data: context.url_data.clone(),
        })
    }

    /// Returns true if the URL is definitely invalid. We don't eagerly resolve
    /// URLs in gecko, so we just return false here.
    /// use its |resolved| status.
    pub fn is_invalid(&self) -> bool {
        false
    }

    /// Convert from URLValueData to SpecifiedUrl.
    unsafe fn from_url_value_data(url: &URLValueData) -> Result<Self, ()> {
        let arc_type =
            &url.mString as *const _ as *const RawOffsetArc<String>;
        Ok(CssUrl {
            serialization: Arc::from_raw_offset((*arc_type).clone()),
            extra_data: url.mExtraData.to_safe(),
        })
    }

    /// Returns true if this URL looks like a fragment.
    /// See https://drafts.csswg.org/css-values/#local-urls
    pub fn is_fragment(&self) -> bool {
        self.as_str().chars().next().map_or(false, |c| c == '#')
    }

    /// Return the resolved url as string, or the empty string if it's invalid.
    ///
    /// FIXME(bholley): This returns the unresolved URL while the servo version
    /// returns the resolved URL.
    pub fn as_str(&self) -> &str {
        &*self.serialization
    }

    /// Little helper for Gecko's ffi.
    pub fn as_slice_components(&self) -> (*const u8, usize) {
        (
            self.serialization.as_str().as_ptr(),
            self.serialization.as_str().len(),
        )
    }

    /// Create a bundled URI suitable for sending to Gecko
    /// to be constructed into a css::URLValue
    pub fn for_ffi(&self) -> ServoBundledURI {
        let arc_offset = Arc::into_raw_offset(self.serialization.clone());
        ServoBundledURI {
            mURLString: unsafe { mem::transmute::<_, RawOffsetArc<RustString>>(arc_offset) },
            mExtraData: self.extra_data.get(),
        }
    }
}

impl Parse for CssUrl {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        let url = input.expect_url()?;
        Self::parse_from_string(url.as_ref().to_owned(), context)
    }
}

impl Eq for CssUrl {}

impl MallocSizeOf for CssUrl {
    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
        // XXX: measure `serialization` once bug 1397971 lands

        // We ignore `extra_data`, because RefPtr is tricky, and there aren't
        // many of them in practise (sharing is common).

        0
    }
}

/// A specified url() value for general usage.
#[derive(Clone, Debug, ToComputedValue, ToCss)]
pub struct SpecifiedUrl {
    /// The specified url value.
    pub url: CssUrl,
    /// Gecko's URLValue so that we can reuse it while rematching a
    /// property with this specified value.
    #[css(skip)]
    pub url_value: RefPtr<URLValue>,
}

impl SpecifiedUrl {
    fn from_css_url(url: CssUrl) -> Self {
        let url_value = unsafe {
            let ptr = bindings::Gecko_NewURLValue(url.for_ffi());
            // We do not expect Gecko_NewURLValue returns null.
            debug_assert!(!ptr.is_null());
            RefPtr::from_addrefed(ptr)
        };
        SpecifiedUrl { url, url_value }
    }

    /// Convert from URLValueData to SpecifiedUrl.
    pub unsafe fn from_url_value_data(url: &URLValueData) -> Result<Self, ()> {
        CssUrl::from_url_value_data(url).map(Self::from_css_url)
    }
}

impl PartialEq for SpecifiedUrl {
    fn eq(&self, other: &Self) -> bool {
        self.url.eq(&other.url)
    }
}

impl Eq for SpecifiedUrl {}

impl Parse for SpecifiedUrl {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        CssUrl::parse(context, input).map(Self::from_css_url)
    }
}

impl MallocSizeOf for SpecifiedUrl {
    fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
        let mut n = self.url.size_of(ops);
        // Although this is a RefPtr, this is the primary reference because
        // SpecifiedUrl is responsible for creating the url_value. So we
        // measure unconditionally here.
        n += unsafe { bindings::Gecko_URLValue_SizeOfIncludingThis(self.url_value.get()) };
        n
    }
}

/// A specified url() value for image.
///
/// This exists so that we can construct `ImageValue` and reuse it.
#[derive(Clone, Debug, ToComputedValue, ToCss)]
pub struct SpecifiedImageUrl {
    /// The specified url value.
    pub url: CssUrl,
    /// Gecko's ImageValue so that we can reuse it while rematching a
    /// property with this specified value.
    #[css(skip)]
    pub image_value: RefPtr<ImageValue>,
}

impl SpecifiedImageUrl {
    fn from_css_url(url: CssUrl) -> Self {
        let image_value = unsafe {
            let ptr = bindings::Gecko_ImageValue_Create(url.for_ffi());
            // We do not expect Gecko_ImageValue_Create returns null.
            debug_assert!(!ptr.is_null());
            RefPtr::from_addrefed(ptr)
        };
        SpecifiedImageUrl { url, image_value }
    }

    /// Parse a URL from a string value. See SpecifiedUrl::parse_from_string.
    pub fn parse_from_string<'a>(
        url: String,
        context: &ParserContext,
    ) -> Result<Self, ParseError<'a>> {
        CssUrl::parse_from_string(url, context).map(Self::from_css_url)
    }

    /// Convert from URLValueData to SpecifiedUrl.
    pub unsafe fn from_url_value_data(url: &URLValueData) -> Result<Self, ()> {
        CssUrl::from_url_value_data(url).map(Self::from_css_url)
    }

    /// Convert from nsStyleImageRequest to SpecifiedUrl.
    pub unsafe fn from_image_request(image_request: &nsStyleImageRequest) -> Result<Self, ()> {
        if image_request.mImageValue.mRawPtr.is_null() {
            return Err(());
        }

        let image_value = image_request.mImageValue.mRawPtr.as_ref().unwrap();
        let url_value_data = &image_value._base;
        Self::from_url_value_data(url_value_data)
    }
}

impl Parse for SpecifiedImageUrl {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        CssUrl::parse(context, input).map(Self::from_css_url)
    }
}

impl PartialEq for SpecifiedImageUrl {
    fn eq(&self, other: &Self) -> bool {
        self.url.eq(&other.url)
    }
}

impl Eq for SpecifiedImageUrl {}

impl MallocSizeOf for SpecifiedImageUrl {
    fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
        let mut n = self.url.size_of(ops);
        // Although this is a RefPtr, this is the primary reference because
        // SpecifiedUrl is responsible for creating the image_value. So we
        // measure unconditionally here.
        n += unsafe { bindings::Gecko_ImageValue_SizeOfIncludingThis(self.image_value.get()) };
        n
    }
}

/// The computed value of a CSS `url()`.
pub type ComputedUrl = SpecifiedUrl;
/// The computed value of a CSS `url()` for image.
pub type ComputedImageUrl = SpecifiedImageUrl;