use async_trait::async_trait;
use libc::off_t;
use nix::fcntl::{fallocate, open, openat, FallocateFlags, OFlag};
use nix::sys::{
    stat::Mode,
    uio::{pread, pwrite},
};
use nix::unistd::{close, ftruncate, mkdir, unlinkat, UnlinkatFlags};
use rand::{seq::SliceRandom, Rng};
use std::os::unix::io::RawFd;

use growthring::wal::{
    WALBytes, WALFile, WALLoader, WALPos, WALRingId, WALStore, WALWriter,
};

struct WALFileTest {
    filename: String,
    fd: RawFd,
}

impl WALFileTest {
    fn new(rootfd: RawFd, filename: &str) -> Result<Self, ()> {
        openat(
            rootfd,
            filename,
            OFlag::O_CREAT | OFlag::O_RDWR,
            Mode::S_IRUSR | Mode::S_IWUSR,
        )
        .and_then(|fd| {
            let filename = filename.to_string();
            Ok(WALFileTest { filename, fd })
        })
        .or_else(|_| Err(()))
    }
}

impl Drop for WALFileTest {
    fn drop(&mut self) {
        close(self.fd).unwrap();
    }
}

#[async_trait(?Send)]
impl WALFile for WALFileTest {
    async fn allocate(&self, offset: WALPos, length: usize) -> Result<(), ()> {
        println!(
            "{}.allocate(offset=0x{:x}, end=0x{:x})",
            self.filename,
            offset,
            offset + length as u64
        );
        fallocate(
            self.fd,
            FallocateFlags::FALLOC_FL_ZERO_RANGE,
            offset as off_t,
            length as off_t,
        )
        .and_then(|_| Ok(()))
        .or_else(|_| Err(()))
    }

    fn truncate(&self, length: usize) -> Result<(), ()> {
        println!("{}.truncate(length={})", self.filename, length);
        ftruncate(self.fd, length as off_t).or_else(|_| Err(()))
    }

    async fn write(&self, offset: WALPos, data: WALBytes) -> Result<(), ()> {
        println!(
            "{}.write(offset=0x{:x}, end=0x{:x}, data=0x{})",
            self.filename,
            offset,
            offset + data.len() as u64,
            hex::encode(&data)
        );
        pwrite(self.fd, &*data, offset as off_t)
            .or_else(|_| Err(()))
            .and_then(|nwrote| {
                if nwrote == data.len() {
                    Ok(())
                } else {
                    Err(())
                }
            })
    }

    fn read(
        &self,
        offset: WALPos,
        length: usize,
    ) -> Result<Option<WALBytes>, ()> {
        let mut buff = Vec::new();
        buff.resize(length, 0);
        pread(self.fd, &mut buff[..], offset as off_t)
            .or_else(|_| Err(()))
            .and_then(|nread| {
                Ok(if nread == length {
                    Some(buff.into_boxed_slice())
                } else {
                    None
                })
            })
    }
}

struct WALStoreTest {
    rootfd: RawFd,
    rootpath: String,
}

impl WALStoreTest {
    fn new(wal_dir: &str, truncate: bool) -> Self {
        let rootpath = wal_dir.to_string();
        if truncate {
            let _ = std::fs::remove_dir_all(wal_dir);
        }
        match mkdir(wal_dir, Mode::S_IRUSR | Mode::S_IWUSR | Mode::S_IXUSR) {
            Err(e) => {
                if truncate {
                    panic!("error while creating directory: {}", e)
                }
            }
            Ok(_) => (),
        }
        let rootfd = match open(
            wal_dir,
            OFlag::O_DIRECTORY | OFlag::O_PATH,
            Mode::empty(),
        ) {
            Ok(fd) => fd,
            Err(_) => panic!("error while opening the DB"),
        };
        WALStoreTest { rootfd, rootpath }
    }
}

impl Drop for WALStoreTest {
    fn drop(&mut self) {
        close(self.rootfd).unwrap();
    }
}

#[async_trait(?Send)]
impl WALStore for WALStoreTest {
    type FileNameIter = std::vec::IntoIter<String>;

    async fn open_file(
        &self,
        filename: &str,
        touch: bool,
    ) -> Result<Box<dyn WALFile>, ()> {
        println!("open_file(filename={}, touch={})", filename, touch);
        let filename = filename.to_string();
        WALFileTest::new(self.rootfd, &filename)
            .and_then(|f| Ok(Box::new(f) as Box<dyn WALFile>))
    }

    async fn remove_file(&self, filename: String) -> Result<(), ()> {
        println!("remove_file(filename={})", filename);
        unlinkat(
            Some(self.rootfd),
            filename.as_str(),
            UnlinkatFlags::NoRemoveDir,
        )
        .or_else(|_| Err(()))
    }

    fn enumerate_files(&self) -> Result<Self::FileNameIter, ()> {
        println!("enumerate_files()");
        let mut logfiles = Vec::new();
        for fname in std::fs::read_dir(&self.rootpath).unwrap() {
            logfiles.push(fname.unwrap().file_name().into_string().unwrap())
        }
        Ok(logfiles.into_iter())
    }

    fn apply_payload(
        &self,
        payload: WALBytes,
        ringid: WALRingId,
    ) -> Result<(), ()> {
        println!(
            "apply_payload(payload={}, ringid={:?})",
            std::str::from_utf8(&payload).unwrap(),
            ringid
        );
        Ok(())
    }
}

fn test(
    records: Vec<String>,
    wal: &mut WALWriter<WALStoreTest>,
) -> Vec<WALRingId> {
    let records: Vec<WALBytes> = records
        .into_iter()
        .map(|s| s.into_bytes().into_boxed_slice())
        .collect();
    let mut res = Vec::new();
    for r in wal.grow(&records).into_iter() {
        let ring_id = futures::executor::block_on(r).unwrap();
        println!("got ring id: {:?}", ring_id);
        res.push(ring_id);
    }
    res
}

fn main() {
    let mut rng = rand::thread_rng();
    let store = WALStoreTest::new("./wal_demo1", true);
    let mut wal = WALLoader::new(9, 8, 1000).recover(store).unwrap();
    for _ in 0..3 {
        test(
            ["hi", "hello", "lol"]
                .iter()
                .map(|s| s.to_string())
                .collect::<Vec<String>>(),
            &mut wal,
        );
    }
    for _ in 0..3 {
        test(
            vec!["a".repeat(10), "b".repeat(100), "c".repeat(1000)],
            &mut wal,
        );
    }

    let store = WALStoreTest::new("./wal_demo1", false);
    let mut wal = WALLoader::new(9, 8, 1000).recover(store).unwrap();
    for _ in 0..3 {
        test(
            vec![
                "a".repeat(10),
                "b".repeat(100),
                "c".repeat(300),
                "d".repeat(400),
            ],
            &mut wal,
        );
    }

    let store = WALStoreTest::new("./wal_demo1", false);
    let mut wal = WALLoader::new(9, 8, 1000).recover(store).unwrap();
    for _ in 0..3 {
        let mut ids = Vec::new();
        for _ in 0..3 {
            let mut records = Vec::new();
            for _ in 0..100 {
                records.push("a".repeat(rng.gen_range(1, 10)))
            }
            for id in test(records, &mut wal).iter() {
                ids.push(*id)
            }
        }
        ids.shuffle(&mut rng);
        for e in ids.chunks(20) {
            println!("peel(20)");
            futures::executor::block_on(wal.peel(e)).unwrap();
        }
    }
}