#[macro_use]
extern crate proptest;

use proptest::collection::vec;
use proptest::test_runner::Config;

use ropey::Rope;

use backend::change::{ApplyChange, Change};

fn make_edit_list_valid(edits: &mut Vec<(usize, usize, String)>, start_text: &str) {
    edits.sort_by_key(|e| e.0);
    let mut tail = 0;
    for e in edits.iter_mut() {
        e.0 = e.0.max(tail);
        while e.0 < start_text.len() && !start_text.is_char_boundary(e.0) {
            e.0 += 1;
        }
        while (e.0 + e.1) < start_text.len() && !start_text.is_char_boundary(e.0 + e.1) {
            e.1 += 1;
        }
        tail = e.0 + e.1;
    }
    for i in (0..edits.len()).rev() {
        if edits[i].0 > start_text.len() {
            edits.remove(i);
        } else if (edits[i].0 + edits[i].1) > start_text.len() {
            edits[i].1 = start_text.len() - edits[i].0;
        }
    }
}

proptest! {
    #![proptest_config(Config::with_cases(512))]

    #[test]
    fn compose(
        ref start_text in "\\PC{0, 200}",
        mut edits1 in vec((0usize..100, 0usize..10, "\\PC{0, 10}"), 0..5),
        mut edits2 in vec((0usize..100, 0usize..10, "\\PC{0, 10}"), 0..5),
    ) {
        // Make edits1 valid and compute the post-edits1 string.
        make_edit_list_valid(&mut edits1, start_text);
        let change1 = Change::from_ordered_edit_set(edits1.iter().map(|e| {
            (e.0, &start_text[e.0..(e.0+e.1)], &e.2[..])
        }));
        let mut r1 = Rope::from_str(start_text);
        r1.apply_change(&change1);
        let text1: String = r1.clone().into();

        // Make edits2 valid and compute the post-edits2 string.
        make_edit_list_valid(&mut edits2, &text1);
        let change2 = Change::from_ordered_edit_set(edits2.iter().map(|e| {
            (e.0, &text1[e.0..(e.0+e.1)], &e.2[..])
        }));
        r1.apply_change(&change2);

        // Do the test!
        let change3 = change1.compose(&change2);
        let mut r2 = Rope::from_str(start_text);
        r2.apply_change(&change3);

        assert_eq!(r1, r2);
    }
}