use std::{process::{exit, Command, Stdio, Child}, env, rc::Rc, io::{Read, self}, cell::RefCell, fs::{File, self}, os::fd::FromRawFd, sync::OnceLock, path::PathBuf};

use matrix_lang::prelude::*;
use matrix_macros::native_func;
use os_info::Info;
use crate::{VmArgs, error, unpack_args};

#[native_func(1)]
fn sys_exit(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [value] = unpack_args!(args);
    let Value::Int(i) = value else {
        return error!("exit requires a int exit code")
    };
    exit(i as i32);
}

#[native_func(0)]
fn argv(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    Ok(Value::List(
            Gc::new(
                env::args()
                .map(|a| Value::String(Rc::from(a.as_str())))
                .collect()
    )))
}

#[native_func(1)]
fn env(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [value] = unpack_args!(args);
    let Value::String(value) = value else {
        return error!("env requires a string name")
    };
    match std::env::var(value.as_ref()) {
        Ok(v) => Ok(Value::String(v.into())),
        Err(e) => error!("couldn't read env var: {e}")
    }
}

fn exec_impl(cmd: io::Result<Child>) -> Result<Value> {
    let mut child = match cmd {
        Ok(c) => c,
        Err(e) => return error!("error executing command: {e}")
    };
    let status = match child.wait() {
        Ok(s) => s,
        Err(e) => return error!("error executing command: {e}")
    };

    let stdout = match child.stdout {
        Some(ref mut out) => {
            let mut buf = String::new();
            let _ = out.read_to_string(&mut buf);
            buf
        },
        None => String::new()
    };

    let stderr = match child.stderr {
        Some(ref mut err) => {
            let mut buf = String::new();
            let _ = err.read_to_string(&mut buf);
            buf
        },
        None => String::new()
    };

    let mut res = ValueMap::new();
    res.insert(Value::from("success"), Value::Bool(status.success()))?;
    res.insert(Value::from("code"), Value::Int(status.code().unwrap_or(0) as i64))?;
    res.insert(Value::from("out"), Value::String(stdout.into()))?;
    res.insert(Value::from("err"), Value::String(stderr.into()))?;

    Ok(Value::Table(res.into()))
}

#[native_func(2)]
fn exec(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [cmd, args] = unpack_args!(args);
    let (cmd, args) = match (cmd, args) {
        (Value::String(s), Value::List(l)) => (s, l.into_inner()),
        _ => return error!("exec requires a string cmd and string argument list")
    };
    let mut sargs = Vec::new();
    for arg in args {
        let Value::String(arg) = arg else {
            return error!("exec requires a string cmd and string argument list")
        };
        sargs.push(arg.to_string());
    };
    let cmd = Command::new(cmd.to_string())
        .args(sargs)
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .spawn();

    exec_impl(cmd)
}

#[native_func(1)]
fn system(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [cmd] = unpack_args!(args);
    let Value::String(cmd) = cmd else {
        return error!("system requires a full command argument string")
    };
    let sh = String::from("/bin/sh");
    let args = vec!["-c".to_string(), cmd.to_string()];

    let cmd = Command::new(sh)
        .args(args)
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .spawn();

    exec_impl(cmd)
}

#[native_func(1)]
fn systemi(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [cmd] = unpack_args!(args);
    let Value::String(cmd) = cmd else {
        return error!("systemi requires a full command argument string")
    };
    let sh = String::from("/bin/sh");
    let args = vec!["-c".to_string(), cmd.to_string()];

    let cmd = Command::new(sh)
        .args(args)
        .stdin(Stdio::inherit())
        .stdout(Stdio::inherit())
        .stderr(Stdio::inherit())
        .spawn();

    exec_impl(cmd)
}

fn stdin() -> Value {
    let f = unsafe { File::from_raw_fd(0) };
    Value::File(Rc::new(RefCell::new(f)))
}

fn stdout() -> Value {
    let f = unsafe { File::from_raw_fd(1) };
    Value::File(Rc::new(RefCell::new(f)))
}

fn stderr() -> Value {
    let f = unsafe { File::from_raw_fd(2) };
    Value::File(Rc::new(RefCell::new(f)))
}

const OS_INFO: OnceLock<Info> = OnceLock::new();

#[native_func(0)]
fn os_type(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    Ok(Value::String(OS_INFO.get_or_init(|| os_info::get()).os_type().to_string().into()))
}

#[native_func(0)]
fn os_version(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    Ok(Value::String(OS_INFO.get_or_init(|| os_info::get()).version().to_string().into()))
}

#[native_func(0)]
fn os_edition(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    Ok(Value::String(OS_INFO.get_or_init(|| os_info::get()).edition().unwrap_or("Unknown").into()))
}

#[native_func(0)]
fn os_bitness(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    Ok(Value::String(OS_INFO.get_or_init(|| os_info::get()).bitness().to_string().into()))
}

#[native_func(0)]
fn os_arch(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    Ok(Value::String(OS_INFO.get_or_init(|| os_info::get()).architecture().unwrap_or("Unknown").into()))
}

#[native_func(0)]
fn cwd(_: VmArgs, _: Vec<Value>) -> Result<Value> {
    match env::current_dir() {
        Ok(v) => Ok(Value::String(v.into_os_string().into_string().unwrap_or(String::new()).into())),
        Err(e) => error!("cant get cwd: {e}")
    }
}

#[native_func(1)]
fn basename(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [value] = unpack_args!(args);
    let Value::String(value) = value else {
        return error!("basename requires a string path")
    };
    let path = PathBuf::from(value.to_string());
    match path.file_name() {
        Some(p) => Ok(Value::String(p.to_str().unwrap().into())),
        None => Ok(Value::String(value.into()))
    }
}

#[native_func(1)]
fn dirname(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [value] = unpack_args!(args);
    let Value::String(value) = value else {
        return error!("basename requires a string path")
    };
    let path = PathBuf::from(value.to_string());
    let parent = match path.parent() {
        Some(p) => p,
        None => path.as_path()
    };
    let str = parent.as_os_str().to_str().unwrap();
    match str {
        "" => Ok(Value::String(".".into())),
        s => Ok(Value::String(s.into()))
    }
}

#[native_func(1)]
fn realpath(_: VmArgs, args: Vec<Value>) -> Result<Value> {
    let [value] = unpack_args!(args);
    let Value::String(value) = value else {
        return error!("basename requires a string path")
    };
    let path = match fs::canonicalize(value.as_ref()) {
        Ok(p) => p,
        Err(e) => return error!("could not get realpath: {e}")
    };
    Ok(Value::String(path.to_str().unwrap().into()))
}


pub fn load(vm: &mut Vm) {
    vm.load_global_fn(sys_exit(), "exit");
    vm.load_global_fn(argv(), "argv");
    vm.load_global_fn(exec(), "exec");
    vm.load_global_fn(system(), "system");
    vm.load_global_fn(systemi(), "systemi");
    vm.load_global_fn(env(), "env");
    vm.load_global(stdin(), "stdin");
    vm.load_global(stdout(), "stdout");
    vm.load_global(stderr(), "stderr");
    vm.load_global_fn(os_type(), "os_type");
    vm.load_global_fn(os_version(), "os_version");
    vm.load_global_fn(os_edition(), "os_edition");
    vm.load_global_fn(os_bitness(), "os_bitness");
    vm.load_global_fn(os_arch(), "os_arch");
    vm.load_global_fn(cwd(), "cwd");
    vm.load_global_fn(basename(), "basename");
    vm.load_global_fn(dirname(), "dirname");
    vm.load_global_fn(realpath(), "realpath");
}