use aho_corasick::{AhoCorasick, AhoCorasickBuilder};
use css_minify::optimizations::{Level, Minifier};
use lazy_static::lazy_static;

use std::str::from_utf8_unchecked;

use crate::err::ProcessingResult;
use crate::proc::checkpoint::WriteCheckpoint;
use crate::proc::MatchAction::*;
use crate::proc::MatchMode::*;
use crate::proc::Processor;
use crate::Cfg;

lazy_static! {
    static ref STYLE_END: AhoCorasick = AhoCorasickBuilder::new()
        .ascii_case_insensitive(true)
        .build(&["</style"]);
}

#[inline(always)]
pub fn process_style(proc: &mut Processor, cfg: &Cfg) -> ProcessingResult<()> {
    let start = WriteCheckpoint::new(proc);
    proc.require_not_at_end()?;
    let src = proc.m(WhileNotSeq(&STYLE_END), Discard);
    // `process_tag` will require closing tag.

    if cfg.minify_css {
        let result = Minifier::default()
            .minify(unsafe { from_utf8_unchecked(&proc[src]) }, Level::Three)
            .ok();
        // TODO Collect error as warning.
        if result.as_ref().filter(|r| r.len() < src.len()).is_some() {
            proc.write_slice(result.unwrap().as_bytes());
        } else {
            proc.write_range(src);
        };
    } else {
        proc.write_range(src);
    };

    Ok(())
}