use anyhow::Result;
use serde::Serialize;
use std::path::Path;

#[derive(Debug, Clone, Serialize)]
pub struct PerRequestRow {
    pub req_id: u64,
    pub arrival: f64,
    pub ttft: f64,
    pub e2e: f64,
    pub bucket: u32,
    pub instance: u32,
    pub length_bucket_match: bool,
    pub total_blocks: u32,
    pub l0_hit_blocks: u32,
    pub l1_hit_blocks: u32,
    pub remote_hit_blocks: u32,
    pub miss_blocks: u32,
    pub rdma_bytes: u64,
    pub pcie_bytes: u64,
    pub probe_overhead_s: f64,
}

pub struct PerRequestWriter {
    inner: csv::Writer<std::fs::File>,
}

impl PerRequestWriter {
    pub fn create<P: AsRef<Path>>(path: P) -> Result<Self> {
        let f = std::fs::File::create(path)?;
        let inner = csv::Writer::from_writer(f);
        Ok(Self { inner })
    }

    pub fn write(&mut self, row: &PerRequestRow) -> Result<()> {
        self.inner.serialize(row)?;
        Ok(())
    }

    pub fn finish(mut self) -> Result<()> {
        self.inner.flush()?;
        Ok(())
    }
}