use std::collections::HashSet;
use std::os::unix::fs::MetadataExt;

use anyhow::{Error};
use serde_json::Value;
use lazy_static::lazy_static;

use super::LsblkInfo;

lazy_static!{
    static ref LVM_UUIDS: HashSet<&'static str> = {
        let mut set = HashSet::new();
        set.insert("e6d6d379-f507-44c2-a23c-238f2a3df928");
        set
    };
}

/// Get set of devices used by LVM (pvs).
///
/// The set is indexed by using the unix raw device number (dev_t is u64)
pub fn get_lvm_devices(
    lsblk_info: &[LsblkInfo],
) -> Result<HashSet<u64>, Error> {

    const PVS_BIN_PATH: &str = "pvs";

    let mut command = std::process::Command::new(PVS_BIN_PATH);
    command.args(&["--reportformat", "json", "--noheadings", "--readonly", "-o", "pv_name"]);

    let output = pbs_tools::run_command(command, None)?;

    let mut device_set: HashSet<u64> = HashSet::new();

    for info in lsblk_info.iter() {
        if let Some(partition_type) = &info.partition_type {
            if LVM_UUIDS.contains(partition_type.as_str()) {
                let meta = std::fs::metadata(&info.path)?;
                device_set.insert(meta.rdev());
            }
        }
    }

    let output: Value = output.parse()?;

    match output["report"][0]["pv"].as_array() {
        Some(list) => {
            for info in list {
                if let Some(pv_name) = info["pv_name"].as_str() {
                    let meta = std::fs::metadata(pv_name)?;
                    device_set.insert(meta.rdev());
                }
            }
        }
        None => return Ok(device_set),
    }

    Ok(device_set)
}