/* 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 std::str;

use encoding::label::encoding_from_whatwg_label;

use encoding::all::UTF_8;

use encoding::{EncodingRef, DecodeReplace, decode};

use tokenizer::{tokenize, Tokenizer};

use parser::{parse_stylesheet_rules, StylesheetParser};

/// Determine the character encoding of a CSS stylesheet and decode it.

///

/// This is based on the presence of a :abbr:`BOM (Byte Order Mark)`,

/// an `@charset` rule,

/// and encoding meta-information.

///

/// :param css_bytes: A byte string.

/// :param protocol_encoding:

/// The encoding label, if any, defined by HTTP or equivalent protocol.

/// (e.g. via the `charset` parameter of the `Content-Type` header.)

/// :param environment_encoding:

/// An optional `Encoding` object

/// for the `environment encoding

/// <http://www.w3.org/TR/css-syntax/#environment-encoding>`_,

/// if any.

/// :returns:

/// A 2-tuple of a decoded Unicode string

/// and the `Encoding` object that was used.

pub fn decode_stylesheet_bytes(css: &[u8], protocol_encoding_label: Option<&str>,

environment_encoding: Option<EncodingRef>)

-> (~str, EncodingRef) {

// http://dev.w3.org/csswg/css-syntax/#the-input-byte-stream

match protocol_encoding_label {

None => (),

Some(label) => match encoding_from_whatwg_label(label) {

None => (),

Some(fallback) => return decode_replace(css, fallback)

}

}

if css.starts_with("@charset \"".as_bytes()) {

// 10 is "@charset \"".len()

// 100 is arbitrary so that no encoding label is more than 100-10 bytes.

match css.slice(10, css.len().min(&100)).position_elem(&('"' as u8)) {

None => (),

Some(label_length)

=> if css.slice_from(10 + label_length).starts_with("\";".as_bytes()) {

let label = css.slice(10, 10 + label_length);

let label = str::from_chars(label.iter().map(|&b| b as char).to_owned_vec());

match encoding_from_whatwg_label(label) {

None => (),

Some(fallback) => match fallback.name() {

"utf-16be" | "utf-16le"

=> return decode_replace(css, UTF_8 as EncodingRef),

_ => return decode_replace(css, fallback),

}

}

}

}

}

match environment_encoding {

None => (),

Some(fallback) => return decode_replace(css, fallback)

}

return decode_replace(css, UTF_8 as EncodingRef)

}

#[inline]

fn decode_replace(input: &[u8], fallback_encoding: EncodingRef)-> (~str, EncodingRef) {

let (result, used_encoding) = decode(input, DecodeReplace, fallback_encoding);

(result.unwrap(), used_encoding)

}

/// Parse stylesheet from bytes.

///

/// :param css_bytes: A byte string.

/// :param protocol_encoding:

/// The encoding label, if any, defined by HTTP or equivalent protocol.

/// (e.g. via the `charset` parameter of the `Content-Type` header.)

/// :param environment_encoding:

/// An optional `Encoding` object

/// for the `environment encoding

/// <http://www.w3.org/TR/css-syntax/#environment-encoding>`_,

/// if any.

/// :returns:

/// A 2-tuple of a Iterator<Result<Rule, SyntaxError>>

/// and the `Encoding` object that was used.

pub fn parse_stylesheet_rules_from_bytes(

css_bytes: &[u8], protocol_encoding_label: Option<&str>,

environment_encoding: Option<EncodingRef>)

-> (StylesheetParser<Tokenizer>, EncodingRef) {

let (css_unicode, encoding) = decode_stylesheet_bytes(

css_bytes, protocol_encoding_label, environment_encoding);

(parse_stylesheet_rules(tokenize(css_unicode)), encoding)

}