/* 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 app_units::Au;
use libc::c_char;
use num::ToPrimitive;
use std::borrow::ToOwned;
use std::convert::AsRef;
use std::ffi::CStr;
use std::fmt;
use std::iter::{Filter, Peekable};
use std::ops::{Deref, DerefMut};
use std::str::{Bytes, Split, from_utf8};
use string_cache::Atom;

#[derive(Clone, Debug, Deserialize, Eq, Hash, HeapSizeOf, Ord, PartialEq, PartialOrd, Serialize)]
pub struct DOMString(String);

impl !Send for DOMString {}

impl DOMString {
    pub fn new() -> DOMString {
        DOMString(String::new())
    }
    pub fn from_string(s: String) -> DOMString {
        DOMString(s)
    }
    // FIXME(ajeffrey): implement more of the String methods on DOMString?
    pub fn push_str(&mut self, string: &str) {
        self.0.push_str(string)
    }
    pub fn clear(&mut self) {
        self.0.clear()
    }

    pub fn bytes(&self) -> Bytes {
        self.0.bytes()
    }
}

impl Default for DOMString {
    fn default() -> Self {
        DOMString(String::new())
    }
}

impl Deref for DOMString {
    type Target = str;

    #[inline]
    fn deref(&self) -> &str {
        &self.0
    }
}

impl DerefMut for DOMString {
    #[inline]
    fn deref_mut(&mut self) -> &mut str {
        &mut self.0
    }
}

impl AsRef<str> for DOMString {
    fn as_ref(&self) -> &str {
        &self.0
    }
}

impl fmt::Display for DOMString {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&**self, f)
    }
}

impl PartialEq<str> for DOMString {
    fn eq(&self, other: &str) -> bool {
        &**self == other
    }
}

impl<'a> PartialEq<&'a str> for DOMString {
    fn eq(&self, other: &&'a str) -> bool {
        &**self == *other
    }
}

impl From<String> for DOMString {
    fn from(contents: String) -> DOMString {
        DOMString(contents)
    }
}

impl<'a> From<&'a str> for DOMString {
    fn from(contents: &str) -> DOMString {
        DOMString::from(String::from(contents))
    }
}

impl From<DOMString> for Atom {
    fn from(contents: DOMString) -> Atom {
        Atom::from(contents.0)
    }
}

impl From<DOMString> for String {
    fn from(contents: DOMString) -> String {
        contents.0
    }
}

impl Into<Vec<u8>> for DOMString {
    fn into(self) -> Vec<u8> {
        self.0.into()
    }
}

impl Extend<char> for DOMString {
    fn extend<I>(&mut self, iterable: I) where I: IntoIterator<Item=char> {
        self.0.extend(iterable)
    }
}

pub type StaticCharVec = &'static [char];
pub type StaticStringVec = &'static [&'static str];

/// A "space character" according to:
///
/// https://html.spec.whatwg.org/multipage/#space-character
pub static HTML_SPACE_CHARACTERS: StaticCharVec = &[
    '\u{0020}',
    '\u{0009}',
    '\u{000a}',
    '\u{000c}',
    '\u{000d}',
];

#[inline]
pub fn char_is_whitespace(c: char) -> bool {
    HTML_SPACE_CHARACTERS.contains(&c)
}

pub fn is_whitespace(s: &str) -> bool {
    s.chars().all(char_is_whitespace)
}

pub fn split_html_space_chars<'a>(s: &'a str) ->
                                  Filter<Split<'a, StaticCharVec>, fn(&&str) -> bool> {
    fn not_empty(&split: &&str) -> bool { !split.is_empty() }
    s.split(HTML_SPACE_CHARACTERS).filter(not_empty as fn(&&str) -> bool)
}


fn is_ascii_digit(c: &char) -> bool {
    match *c {
        '0'...'9' => true,
        _ => false,
    }
}

fn is_decimal_point(c: char) -> bool {
    c == '.'
}

fn is_exponent_char(c: char) -> bool {
    match c {
        'e' | 'E' => true,
        _ => false,
    }
}

pub fn read_numbers<I: Iterator<Item=char>>(mut iter: Peekable<I>) -> (Option<i64>, usize) {
    match iter.peek() {
        Some(c) if is_ascii_digit(c) => (),
        _ => return (None, 0),
    }

    iter.take_while(is_ascii_digit).map(|d| {
        d as i64 - '0' as i64
    }).fold((Some(0i64), 0), |accumulator, d| {
        let digits = accumulator.0.and_then(|accumulator| {
            accumulator.checked_mul(10)
        }).and_then(|accumulator| {
            accumulator.checked_add(d)
        });
        (digits, accumulator.1 + 1)
    })
}

pub fn read_fraction<I: Iterator<Item=char>>(mut iter: Peekable<I>,
                                             mut divisor: f64,
                                             value: f64) -> (f64, usize) {
    match iter.peek() {
        Some(c) if is_decimal_point(*c) => (),
        _ => return (value, 0),
    }
    iter.next();

    iter.take_while(is_ascii_digit).map(|d|
        d as i64 - '0' as i64
    ).fold((value, 1), |accumulator, d| {
        divisor *= 10f64;
        (accumulator.0 + d as f64 / divisor,
            accumulator.1 + 1)
    })
}

pub fn read_exponent<I: Iterator<Item=char>>(mut iter: Peekable<I>) -> Option<i32> {
    match iter.peek() {
        Some(c) if is_exponent_char(*c) => (),
        _ => return None,
    }
    iter.next();

    match iter.peek() {
        None => None,
        Some(&'-') => {
            iter.next();
            read_numbers(iter).0.map(|exp| -exp.to_i32().unwrap_or(0))
        }
        Some(&'+') => {
            iter.next();
            read_numbers(iter).0.map(|exp| exp.to_i32().unwrap_or(0))
        }
        Some(_) => read_numbers(iter).0.map(|exp| exp.to_i32().unwrap_or(0))
    }
}

#[derive(Clone, Copy, Debug, HeapSizeOf, PartialEq)]
pub enum LengthOrPercentageOrAuto {
    Auto,
    Percentage(f32),
    Length(Au),
}

#[derive(Clone, Eq, PartialEq, Hash, Debug, Deserialize, Serialize)]
pub struct LowercaseString {
    inner: String,
}

impl LowercaseString {
    pub fn new(s: &str) -> LowercaseString {
        LowercaseString {
            inner: s.to_lowercase(),
        }
    }
}

impl Deref for LowercaseString {
    type Target = str;

    #[inline]
    fn deref(&self) -> &str {
        &*self.inner
    }
}

/// Creates a String from the given null-terminated buffer.
/// Panics if the buffer does not contain UTF-8.
pub unsafe fn c_str_to_string(s: *const c_char) -> String {
    from_utf8(CStr::from_ptr(s).to_bytes()).unwrap().to_owned()
}

pub fn str_join<I, T>(strs: I, join: &str) -> String
    where I: IntoIterator<Item=T>, T: AsRef<str>,
{
    strs.into_iter().enumerate().fold(String::new(), |mut acc, (i, s)| {
        if i > 0 { acc.push_str(join); }
        acc.push_str(s.as_ref());
        acc
    })
}