#![no_main]

//! Differential fuzzing of pulldown-cmark and commonmark.js.

//!

//! This fuzzer sends the same input to both Markdown parsers and

//! compares the output. The output from commonmark.js is turned into

//! `pulldown_cmark::Event` values for this purpose.

//!

//! Run the fuzzer like this to only test ASCII input (which is

//! usually enough to find parsing differences):

//!

//!     cargo fuzz run commonmark_js -- -only_ascii=1

use libfuzzer_sys::fuzz_target;

use pretty_assertions::assert_eq;

use pulldown_cmark_fuzz::{commonmark_js, normalize, print_events, pulldown_cmark, xml_to_events};

fuzz_target!(|text: String| {

    // There are some differences in handling of non-UTF-8 input.

    if text.bytes().any(|b| b.is_ascii_control() && b != b'\n') {

        return;

    }

    // There are some trivial differences due to trailing whitespace.

    let text = text

        .lines()

        .map(|line| line.trim_end())

        .collect::<Vec<_>>()

        .join("\n");

    let pulldown_cmark_events = normalize(pulldown_cmark(&text));

    let commonmark_js_xml = &commonmark_js(&text).unwrap();

    let raw_events = match xml_to_events(commonmark_js_xml) {

        Ok(raw_events) => raw_events,

        Err(err) => {

            print_events(&text, &pulldown_cmark_events);

            eprintln!("XML from commonmark.js:\n{commonmark_js_xml}");

            panic!("Could not parse XML: {}", err);

        }

    };

    let commonmark_js_events = normalize(raw_events);

    if pulldown_cmark_events != commonmark_js_events {

        eprintln!("Events from pulldown-cmark:\n\n```rust");

        print_events(&text, &pulldown_cmark_events);

        eprintln!("```");

        eprintln!();

        eprintln!("Events from commonmark.js:\n\n```rust");

        print_events(&text, &commonmark_js_events);

        eprintln!("```");

        eprintln!();

        let dingus_url = format!(

            "https://spec.commonmark.org/dingus/?text={}",

            urlencoding::encode(&text)

        );

        eprintln!("XML from [commonmark.js]({dingus_url}):\n\n```xml\n{commonmark_js_xml}```");

        eprintln!();

        assert_eq!(pulldown_cmark_events, commonmark_js_events);

    }

});