// Copyright 2020 Tyler Neely
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

mod util;

use pretty_assertions::assert_eq;

use rocksdb::{DBCompactionStyle, MergeOperands, Options, DB};
use util::DBPath;

fn test_provided_merge(
    _new_key: &[u8],
    existing_val: Option<&[u8]>,
    operands: &mut MergeOperands,
) -> Option<Vec<u8>> {
    let nops = operands.size_hint().0;
    let mut result: Vec<u8> = Vec::with_capacity(nops);
    if let Some(v) = existing_val {
        for e in v {
            result.push(*e);
        }
    }
    for op in operands {
        for e in op {
            result.push(*e);
        }
    }
    Some(result)
}

#[test]
fn merge_test() {
    use crate::{Options, DB};

    let db_path = DBPath::new("_rust_rocksdb_merge_test");
    let mut opts = Options::default();
    opts.create_if_missing(true);
    opts.set_merge_operator("test operator", test_provided_merge, None);

    let db = DB::open(&opts, &db_path).unwrap();
    let p = db.put(b"k1", b"a");
    assert!(p.is_ok());
    let _ = db.merge(b"k1", b"b");
    let _ = db.merge(b"k1", b"c");
    let _ = db.merge(b"k1", b"d");
    let _ = db.merge(b"k1", b"efg");
    let m = db.merge(b"k1", b"h");
    assert!(m.is_ok());
    match db.get(b"k1") {
        Ok(Some(value)) => {
            if let Ok(v) = std::str::from_utf8(&value) {
                println!("retrieved utf8 value: {}", v)
            } else {
                println!("did not read valid utf-8 out of the db")
            }
        }
        Err(_) => println!("error reading value"),
        _ => panic!("value not present"),
    }

    assert!(m.is_ok());
    let r = db.get(b"k1");
    assert_eq!(r.unwrap().unwrap(), b"abcdefgh");
    assert!(db.delete(b"k1").is_ok());
    assert!(db.get(b"k1").unwrap().is_none());
}

unsafe fn to_slice<T: Sized>(p: &T) -> &[u8] {
    ::std::slice::from_raw_parts((p as *const T) as *const u8, ::std::mem::size_of::<T>())
}

fn from_slice<T: Sized>(s: &[u8]) -> Option<&T> {
    if std::mem::size_of::<T>() == s.len() {
        unsafe { Some(&*(s.as_ptr() as *const T)) }
    } else {
        println!(
            "slice {:?} is len {}, but T is size {}",
            s,
            s.len(),
            std::mem::size_of::<T>()
        );
        None
    }
}

#[repr(packed)]
#[derive(Copy, Clone, Debug, Default)]
struct ValueCounts {
    num_a: u32,
    num_b: u32,
    num_c: u32,
    num_d: u32,
}

fn test_counting_partial_merge(
    _new_key: &[u8],
    _existing_val: Option<&[u8]>,
    operands: &mut MergeOperands,
) -> Option<Vec<u8>> {
    let nops = operands.size_hint().0;
    let mut result: Vec<u8> = Vec::with_capacity(nops);
    for op in operands {
        for e in op {
            result.push(*e);
        }
    }
    Some(result)
}

fn test_counting_full_merge(
    _new_key: &[u8],
    existing_val: Option<&[u8]>,
    operands: &mut MergeOperands,
) -> Option<Vec<u8>> {
    let mut counts = if let Some(v) = existing_val {
        *from_slice::<ValueCounts>(v).unwrap_or(&ValueCounts::default())
    } else {
        ValueCounts::default()
    };

    for op in operands {
        for e in op {
            match *e {
                b'a' => counts.num_a += 1,
                b'b' => counts.num_b += 1,
                b'c' => counts.num_c += 1,
                b'd' => counts.num_d += 1,
                _ => {}
            }
        }
    }
    let slc = unsafe { to_slice(&counts) };
    Some(slc.to_vec())
}

#[test]
#[allow(clippy::too_many_lines)]
fn counting_merge_test() {
    use std::sync::Arc;
    use std::thread;

    let db_path = DBPath::new("_rust_rocksdb_partial_merge_test");
    let mut opts = Options::default();
    opts.create_if_missing(true);
    opts.set_compaction_style(DBCompactionStyle::Universal);
    opts.set_min_write_buffer_number_to_merge(10);

    opts.set_merge_operator(
        "sort operator",
        test_counting_full_merge,
        Some(test_counting_partial_merge),
    );

    let db = Arc::new(DB::open(&opts, &db_path).unwrap());
    let _ = db.delete(b"k1");
    let _ = db.delete(b"k2");
    let _ = db.merge(b"k1", b"a");
    let _ = db.merge(b"k1", b"b");
    let _ = db.merge(b"k1", b"d");
    let _ = db.merge(b"k1", b"a");
    let _ = db.merge(b"k1", b"a");
    let _ = db.merge(b"k1", b"efg");
    for i in 0..500 {
        let _ = db.merge(b"k2", b"c");
        if i % 20 == 0 {
            let _ = db.get(b"k2");
        }
    }
    for i in 0..500 {
        let _ = db.merge(b"k2", b"c");
        if i % 20 == 0 {
            let _ = db.get(b"k2");
        }
    }
    db.compact_range(None::<&[u8]>, None::<&[u8]>);
    let d1 = db.clone();
    let d2 = db.clone();
    let d3 = db.clone();

    let h1 = thread::spawn(move || {
        for i in 0..500 {
            let _ = d1.merge(b"k2", b"c");
            if i % 20 == 0 {
                let _ = d1.get(b"k2");
            }
        }
        for i in 0..500 {
            let _ = d1.merge(b"k2", b"a");
            if i % 20 == 0 {
                let _ = d1.get(b"k2");
            }
        }
    });
    let h2 = thread::spawn(move || {
        for i in 0..500 {
            let _ = d2.merge(b"k2", b"b");
            if i % 20 == 0 {
                let _ = d2.get(b"k2");
            }
        }
        for i in 0..500 {
            let _ = d2.merge(b"k2", b"d");
            if i % 20 == 0 {
                let _ = d2.get(b"k2");
            }
        }
        d2.compact_range(None::<&[u8]>, None::<&[u8]>);
    });
    h2.join().unwrap();
    let h3 = thread::spawn(move || {
        for i in 0..500 {
            let _ = d3.merge(b"k2", b"a");
            if i % 20 == 0 {
                let _ = d3.get(b"k2");
            }
        }
        for i in 0..500 {
            let _ = d3.merge(b"k2", b"c");
            if i % 20 == 0 {
                let _ = d3.get(b"k2");
            }
        }
    });
    let m = db.merge(b"k1", b"b");
    assert!(m.is_ok());
    h3.join().unwrap();
    h1.join().unwrap();
    match db.get(b"k2") {
        Ok(Some(value)) => match from_slice::<ValueCounts>(&*value) {
            Some(v) => unsafe {
                assert_eq!(v.num_a, 1000);
                assert_eq!(v.num_b, 500);
                assert_eq!(v.num_c, 2000);
                assert_eq!(v.num_d, 500);
            },
            None => panic!("Failed to get ValueCounts from db"),
        },
        Err(e) => panic!("error reading value {:?}", e),
        _ => panic!("value not present"),
    }
    match db.get(b"k1") {
        Ok(Some(value)) => match from_slice::<ValueCounts>(&*value) {
            Some(v) => unsafe {
                assert_eq!(v.num_a, 3);
                assert_eq!(v.num_b, 2);
                assert_eq!(v.num_c, 0);
                assert_eq!(v.num_d, 1);
            },
            None => panic!("Failed to get ValueCounts from db"),
        },
        Err(e) => panic!("error reading value {:?}", e),
        _ => panic!("value not present"),
    }
}

#[test]
fn failed_merge_test() {
    fn test_failing_merge(
        _key: &[u8],
        _val: Option<&[u8]>,
        _operands: &mut MergeOperands,
    ) -> Option<Vec<u8>> {
        None
    }
    use crate::{Options, DB};

    let db_path = DBPath::new("_rust_rocksdb_failed_merge_test");
    let mut opts = Options::default();
    opts.create_if_missing(true);
    opts.set_merge_operator("test operator", test_failing_merge, None);

    let db = DB::open(&opts, &db_path).expect("open with a merge operator");
    db.put(b"key", b"value").expect("put_ok");
    let res = db.merge(b"key", b"new value");
    match res.and_then(|_e| db.get(b"key")) {
        Ok(val) => panic!("expected merge failure to propagate, got: {:?}", val),
        Err(e) => {
            assert!(e.into_string().contains("Could not perform merge."));
        }
    }
}