use anyhow::{ensure, Context, Ok, Result};
use std::{
    path::{Path, PathBuf},
    process::Command,
};

use crate::apk_sign::get_apk_signature;

const KERNEL_PARAM_PATH: &str = "/sys/module/kernelsu";

fn read_u32(path: &PathBuf) -> Result<u32> {
    let content = std::fs::read_to_string(path)?;
    let content = content.trim();
    let content = content.parse::<u32>()?;
    Ok(content)
}

fn set_kernel_param(size: u32, hash: String) -> Result<()> {
    let kernel_param_path = Path::new(KERNEL_PARAM_PATH).join("parameters");

    let expeced_size_path = kernel_param_path.join("ksu_expected_size");
    let expeced_hash_path = kernel_param_path.join("ksu_expected_hash");

    println!(
        "before size: {:#x} hash: {}",
        read_u32(&expeced_size_path)?,
        std::fs::read_to_string(&expeced_hash_path)?
    );

    std::fs::write(&expeced_size_path, size.to_string())?;
    std::fs::write(&expeced_hash_path, hash)?;

    println!(
        "after size: {:#x} hash: {}",
        read_u32(&expeced_size_path)?,
        std::fs::read_to_string(&expeced_hash_path)?
    );

    Ok(())
}

fn get_apk_path(package_name: &str) -> Result<String> {
    // `cmd package path` is not available below Android 9
    let output = Command::new("pm").args(["path", package_name]).output()?;

    // package:/data/app/<xxxx>/base.apk
    let output = String::from_utf8_lossy(&output.stdout);
    let path = output.trim().replace("package:", "");
    Ok(path)
}

pub fn set_manager(pkg: &str) -> Result<()> {
    ensure!(
        Path::new(KERNEL_PARAM_PATH).exists(),
        "CONFIG_KSU_DEBUG is not enabled"
    );

    let path = get_apk_path(pkg).with_context(|| format!("{pkg} does not exist!"))?;
    let sign = get_apk_signature(&path)?;
    set_kernel_param(sign.0, sign.1)?;
    Ok(())
}
