use rand::RngCore;
use std::iter::{repeat, FromIterator};
use test::{black_box, Bencher};

#[bench]
fn bench_new(b: &mut Bencher) {
    b.iter(|| {
        let v: Vec<u32> = Vec::new();
        assert_eq!(v.len(), 0);
        assert_eq!(v.capacity(), 0);
        v
    })
}

fn do_bench_with_capacity(b: &mut Bencher, src_len: usize) {
    b.bytes = src_len as u64;

    b.iter(|| {
        let v: Vec<u32> = Vec::with_capacity(src_len);
        assert_eq!(v.len(), 0);
        assert_eq!(v.capacity(), src_len);
        v
    })
}

#[bench]
fn bench_with_capacity_0000(b: &mut Bencher) {
    do_bench_with_capacity(b, 0)
}

#[bench]
fn bench_with_capacity_0010(b: &mut Bencher) {
    do_bench_with_capacity(b, 10)
}

#[bench]
fn bench_with_capacity_0100(b: &mut Bencher) {
    do_bench_with_capacity(b, 100)
}

#[bench]
fn bench_with_capacity_1000(b: &mut Bencher) {
    do_bench_with_capacity(b, 1000)
}

fn do_bench_from_fn(b: &mut Bencher, src_len: usize) {
    b.bytes = src_len as u64;

    b.iter(|| {
        let dst = (0..src_len).collect::<Vec<_>>();
        assert_eq!(dst.len(), src_len);
        assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
        dst
    })
}

#[bench]
fn bench_from_fn_0000(b: &mut Bencher) {
    do_bench_from_fn(b, 0)
}

#[bench]
fn bench_from_fn_0010(b: &mut Bencher) {
    do_bench_from_fn(b, 10)
}

#[bench]
fn bench_from_fn_0100(b: &mut Bencher) {
    do_bench_from_fn(b, 100)
}

#[bench]
fn bench_from_fn_1000(b: &mut Bencher) {
    do_bench_from_fn(b, 1000)
}

fn do_bench_from_elem(b: &mut Bencher, src_len: usize) {
    b.bytes = src_len as u64;

    b.iter(|| {
        let dst: Vec<usize> = repeat(5).take(src_len).collect();
        assert_eq!(dst.len(), src_len);
        assert!(dst.iter().all(|x| *x == 5));
        dst
    })
}

#[bench]
fn bench_from_elem_0000(b: &mut Bencher) {
    do_bench_from_elem(b, 0)
}

#[bench]
fn bench_from_elem_0010(b: &mut Bencher) {
    do_bench_from_elem(b, 10)
}

#[bench]
fn bench_from_elem_0100(b: &mut Bencher) {
    do_bench_from_elem(b, 100)
}

#[bench]
fn bench_from_elem_1000(b: &mut Bencher) {
    do_bench_from_elem(b, 1000)
}

fn do_bench_from_slice(b: &mut Bencher, src_len: usize) {
    let src: Vec<_> = FromIterator::from_iter(0..src_len);

    b.bytes = src_len as u64;

    b.iter(|| {
        let dst = src.clone()[..].to_vec();
        assert_eq!(dst.len(), src_len);
        assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
        dst
    });
}

#[bench]
fn bench_from_slice_0000(b: &mut Bencher) {
    do_bench_from_slice(b, 0)
}

#[bench]
fn bench_from_slice_0010(b: &mut Bencher) {
    do_bench_from_slice(b, 10)
}

#[bench]
fn bench_from_slice_0100(b: &mut Bencher) {
    do_bench_from_slice(b, 100)
}

#[bench]
fn bench_from_slice_1000(b: &mut Bencher) {
    do_bench_from_slice(b, 1000)
}

fn do_bench_from_iter(b: &mut Bencher, src_len: usize) {
    let src: Vec<_> = FromIterator::from_iter(0..src_len);

    b.bytes = src_len as u64;

    b.iter(|| {
        let dst: Vec<_> = FromIterator::from_iter(src.clone());
        assert_eq!(dst.len(), src_len);
        assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
        dst
    });
}

#[bench]
fn bench_from_iter_0000(b: &mut Bencher) {
    do_bench_from_iter(b, 0)
}

#[bench]
fn bench_from_iter_0010(b: &mut Bencher) {
    do_bench_from_iter(b, 10)
}

#[bench]
fn bench_from_iter_0100(b: &mut Bencher) {
    do_bench_from_iter(b, 100)
}

#[bench]
fn bench_from_iter_1000(b: &mut Bencher) {
    do_bench_from_iter(b, 1000)
}

fn do_bench_extend(b: &mut Bencher, dst_len: usize, src_len: usize) {
    let dst: Vec<_> = FromIterator::from_iter(0..dst_len);
    let src: Vec<_> = FromIterator::from_iter(dst_len..dst_len + src_len);

    b.bytes = src_len as u64;

    b.iter(|| {
        let mut dst = dst.clone();
        dst.extend(src.clone());
        assert_eq!(dst.len(), dst_len + src_len);
        assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
        dst
    });
}

#[bench]
fn bench_extend_0000_0000(b: &mut Bencher) {
    do_bench_extend(b, 0, 0)
}

#[bench]
fn bench_extend_0000_0010(b: &mut Bencher) {
    do_bench_extend(b, 0, 10)
}

#[bench]
fn bench_extend_0000_0100(b: &mut Bencher) {
    do_bench_extend(b, 0, 100)
}

#[bench]
fn bench_extend_0000_1000(b: &mut Bencher) {
    do_bench_extend(b, 0, 1000)
}

#[bench]
fn bench_extend_0010_0010(b: &mut Bencher) {
    do_bench_extend(b, 10, 10)
}

#[bench]
fn bench_extend_0100_0100(b: &mut Bencher) {
    do_bench_extend(b, 100, 100)
}

#[bench]
fn bench_extend_1000_1000(b: &mut Bencher) {
    do_bench_extend(b, 1000, 1000)
}

fn do_bench_extend_from_slice(b: &mut Bencher, dst_len: usize, src_len: usize) {
    let dst: Vec<_> = FromIterator::from_iter(0..dst_len);
    let src: Vec<_> = FromIterator::from_iter(dst_len..dst_len + src_len);

    b.bytes = src_len as u64;

    b.iter(|| {
        let mut dst = dst.clone();
        dst.extend_from_slice(&src);
        assert_eq!(dst.len(), dst_len + src_len);
        assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
        dst
    });
}

#[bench]
fn bench_extend_recycle(b: &mut Bencher) {
    let mut data = vec![0; 1000];

    b.iter(|| {
        let tmp = std::mem::take(&mut data);
        let mut to_extend = black_box(Vec::new());
        to_extend.extend(tmp.into_iter());
        data = black_box(to_extend);
    });

    black_box(data);
}

#[bench]
fn bench_extend_from_slice_0000_0000(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 0, 0)
}

#[bench]
fn bench_extend_from_slice_0000_0010(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 0, 10)
}

#[bench]
fn bench_extend_from_slice_0000_0100(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 0, 100)
}

#[bench]
fn bench_extend_from_slice_0000_1000(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 0, 1000)
}

#[bench]
fn bench_extend_from_slice_0010_0010(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 10, 10)
}

#[bench]
fn bench_extend_from_slice_0100_0100(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 100, 100)
}

#[bench]
fn bench_extend_from_slice_1000_1000(b: &mut Bencher) {
    do_bench_extend_from_slice(b, 1000, 1000)
}

fn do_bench_clone(b: &mut Bencher, src_len: usize) {
    let src: Vec<usize> = FromIterator::from_iter(0..src_len);

    b.bytes = src_len as u64;

    b.iter(|| {
        let dst = src.clone();
        assert_eq!(dst.len(), src_len);
        assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
        dst
    });
}

#[bench]
fn bench_clone_0000(b: &mut Bencher) {
    do_bench_clone(b, 0)
}

#[bench]
fn bench_clone_0010(b: &mut Bencher) {
    do_bench_clone(b, 10)
}

#[bench]
fn bench_clone_0100(b: &mut Bencher) {
    do_bench_clone(b, 100)
}

#[bench]
fn bench_clone_1000(b: &mut Bencher) {
    do_bench_clone(b, 1000)
}

fn do_bench_clone_from(b: &mut Bencher, times: usize, dst_len: usize, src_len: usize) {
    let dst: Vec<_> = FromIterator::from_iter(0..src_len);
    let src: Vec<_> = FromIterator::from_iter(dst_len..dst_len + src_len);

    b.bytes = (times * src_len) as u64;

    b.iter(|| {
        let mut dst = dst.clone();

        for _ in 0..times {
            dst.clone_from(&src);
            assert_eq!(dst.len(), src_len);
            assert!(dst.iter().enumerate().all(|(i, x)| dst_len + i == *x));
        }
        dst
    });
}

#[bench]
fn bench_clone_from_01_0000_0000(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 0, 0)
}

#[bench]
fn bench_clone_from_01_0000_0010(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 0, 10)
}

#[bench]
fn bench_clone_from_01_0000_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 0, 100)
}

#[bench]
fn bench_clone_from_01_0000_1000(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 0, 1000)
}

#[bench]
fn bench_clone_from_01_0010_0010(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 10, 10)
}

#[bench]
fn bench_clone_from_01_0100_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 100, 100)
}

#[bench]
fn bench_clone_from_01_1000_1000(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 1000, 1000)
}

#[bench]
fn bench_clone_from_01_0010_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 10, 100)
}

#[bench]
fn bench_clone_from_01_0100_1000(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 100, 1000)
}

#[bench]
fn bench_clone_from_01_0010_0000(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 10, 0)
}

#[bench]
fn bench_clone_from_01_0100_0010(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 100, 10)
}

#[bench]
fn bench_clone_from_01_1000_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 1, 1000, 100)
}

#[bench]
fn bench_clone_from_10_0000_0000(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 0, 0)
}

#[bench]
fn bench_clone_from_10_0000_0010(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 0, 10)
}

#[bench]
fn bench_clone_from_10_0000_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 0, 100)
}

#[bench]
fn bench_clone_from_10_0000_1000(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 0, 1000)
}

#[bench]
fn bench_clone_from_10_0010_0010(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 10, 10)
}

#[bench]
fn bench_clone_from_10_0100_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 100, 100)
}

#[bench]
fn bench_clone_from_10_1000_1000(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 1000, 1000)
}

#[bench]
fn bench_clone_from_10_0010_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 10, 100)
}

#[bench]
fn bench_clone_from_10_0100_1000(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 100, 1000)
}

#[bench]
fn bench_clone_from_10_0010_0000(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 10, 0)
}

#[bench]
fn bench_clone_from_10_0100_0010(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 100, 10)
}

#[bench]
fn bench_clone_from_10_1000_0100(b: &mut Bencher) {
    do_bench_clone_from(b, 10, 1000, 100)
}

macro_rules! bench_in_place {
    ($($fname:ident, $type:ty, $count:expr, $init:expr);*) => {
        $(
            #[bench]
            fn $fname(b: &mut Bencher) {
                b.iter(|| {
                    let src: Vec<$type> = black_box(vec![$init; $count]);
                    let mut sink = src.into_iter()
                        .enumerate()
                        .map(|(idx, e)| idx as $type ^ e)
                        .collect::<Vec<$type>>();
                    black_box(sink.as_mut_ptr())
                });
            }
        )+
    };
}

bench_in_place![
    bench_in_place_xxu8_0010_i0,   u8,   10, 0;
    bench_in_place_xxu8_0100_i0,   u8,  100, 0;
    bench_in_place_xxu8_1000_i0,   u8, 1000, 0;
    bench_in_place_xxu8_0010_i1,   u8,   10, 1;
    bench_in_place_xxu8_0100_i1,   u8,  100, 1;
    bench_in_place_xxu8_1000_i1,   u8, 1000, 1;
    bench_in_place_xu32_0010_i0,  u32,   10, 0;
    bench_in_place_xu32_0100_i0,  u32,  100, 0;
    bench_in_place_xu32_1000_i0,  u32, 1000, 0;
    bench_in_place_xu32_0010_i1,  u32,   10, 1;
    bench_in_place_xu32_0100_i1,  u32,  100, 1;
    bench_in_place_xu32_1000_i1,  u32, 1000, 1;
    bench_in_place_u128_0010_i0, u128,   10, 0;
    bench_in_place_u128_0100_i0, u128,  100, 0;
    bench_in_place_u128_1000_i0, u128, 1000, 0;
    bench_in_place_u128_0010_i1, u128,   10, 1;
    bench_in_place_u128_0100_i1, u128,  100, 1;
    bench_in_place_u128_1000_i1, u128, 1000, 1
];

#[bench]
fn bench_in_place_recycle(b: &mut Bencher) {
    let mut data = vec![0; 1000];

    b.iter(|| {
        let tmp = std::mem::take(&mut data);
        data = black_box(
            tmp.into_iter()
                .enumerate()
                .map(|(idx, e)| idx.wrapping_add(e))
                .fuse()
                .peekable()
                .collect::<Vec<usize>>(),
        );
    });
}

#[bench]
fn bench_in_place_zip_recycle(b: &mut Bencher) {
    let mut data = vec![0u8; 1000];
    let mut rng = rand::thread_rng();
    let mut subst = vec![0u8; 1000];
    rng.fill_bytes(&mut subst[..]);

    b.iter(|| {
        let tmp = std::mem::take(&mut data);
        let mangled = tmp
            .into_iter()
            .zip(subst.iter().copied())
            .enumerate()
            .map(|(i, (d, s))| d.wrapping_add(i as u8) ^ s)
            .collect::<Vec<_>>();
        assert_eq!(mangled.len(), 1000);
        data = black_box(mangled);
    });
}

#[bench]
fn bench_in_place_zip_iter_mut(b: &mut Bencher) {
    let mut data = vec![0u8; 256];
    let mut rng = rand::thread_rng();
    let mut subst = vec![0u8; 1000];
    rng.fill_bytes(&mut subst[..]);

    b.iter(|| {
        data.iter_mut().enumerate().for_each(|(i, d)| {
            *d = d.wrapping_add(i as u8) ^ subst[i];
        });
    });

    black_box(data);
}

#[derive(Clone)]
struct Droppable(usize);

impl Drop for Droppable {
    fn drop(&mut self) {
        black_box(self);
    }
}

#[bench]
fn bench_in_place_collect_droppable(b: &mut Bencher) {
    let v: Vec<Droppable> = std::iter::repeat_with(|| Droppable(0)).take(1000).collect();
    b.iter(|| {
        v.clone()
            .into_iter()
            .skip(100)
            .enumerate()
            .map(|(i, e)| Droppable(i ^ e.0))
            .collect::<Vec<_>>()
    })
}

const LEN: usize = 16384;

#[bench]
fn bench_chain_collect(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| data.iter().cloned().chain([1].iter().cloned()).collect::<Vec<_>>());
}

#[bench]
fn bench_chain_chain_collect(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| {
        data.iter()
            .cloned()
            .chain([1].iter().cloned())
            .chain([2].iter().cloned())
            .collect::<Vec<_>>()
    });
}

#[bench]
fn bench_nest_chain_chain_collect(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| {
        data.iter().cloned().chain([1].iter().chain([2].iter()).cloned()).collect::<Vec<_>>()
    });
}

pub fn example_plain_slow(l: &[u32]) -> Vec<u32> {
    let mut result = Vec::with_capacity(l.len());
    result.extend(l.iter().rev());
    result
}

pub fn map_fast(l: &[(u32, u32)]) -> Vec<u32> {
    let mut result = Vec::with_capacity(l.len());
    for i in 0..l.len() {
        unsafe {
            *result.get_unchecked_mut(i) = l[i].0;
            result.set_len(i);
        }
    }
    result
}

#[bench]
fn bench_range_map_collect(b: &mut Bencher) {
    b.iter(|| (0..LEN).map(|_| u32::default()).collect::<Vec<_>>());
}

#[bench]
fn bench_chain_extend_ref(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| {
        let mut v = Vec::<u32>::with_capacity(data.len() + 1);
        v.extend(data.iter().chain([1].iter()));
        v
    });
}

#[bench]
fn bench_chain_extend_value(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| {
        let mut v = Vec::<u32>::with_capacity(data.len() + 1);
        v.extend(data.iter().cloned().chain(Some(1)));
        v
    });
}

#[bench]
fn bench_rev_1(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| {
        let mut v = Vec::<u32>::new();
        v.extend(data.iter().rev());
        v
    });
}

#[bench]
fn bench_rev_2(b: &mut Bencher) {
    let data = black_box([0; LEN]);
    b.iter(|| example_plain_slow(&data));
}

#[bench]
fn bench_map_regular(b: &mut Bencher) {
    let data = black_box([(0, 0); LEN]);
    b.iter(|| {
        let mut v = Vec::<u32>::new();
        v.extend(data.iter().map(|t| t.1));
        v
    });
}

#[bench]
fn bench_map_fast(b: &mut Bencher) {
    let data = black_box([(0, 0); LEN]);
    b.iter(|| map_fast(&data));
}