use std::{io, path::Path, thread};

use crate::error::{CliError, Result};

use super::{
    config::{DebugConfig, ResolvedModDir},
    hotreload::HotReloadTask,
    ipc::DebugIpcServer,
    log::{self, LineBuffer},
};

#[cfg(windows)]
use std::{ffi::OsStr, os::windows::ffi::OsStrExt, ptr};

#[cfg(windows)]
use windows_sys::Win32::{
    Foundation::{
        CloseHandle, ERROR_BROKEN_PIPE, GetLastError, HANDLE, HANDLE_FLAG_INHERIT,
        SetHandleInformation,
    },
    Storage::FileSystem::ReadFile,
    System::{
        Console::{GetStdHandle, STD_INPUT_HANDLE},
        Pipes::CreatePipe,
        Threading::{
            CREATE_UNICODE_ENVIRONMENT, CreateProcessW, INFINITE, PROCESS_INFORMATION,
            STARTF_USESTDHANDLES, STARTUPINFOW, WaitForSingleObject,
        },
    },
};

#[cfg(windows)]
use windows_sys::Win32::Security::SECURITY_ATTRIBUTES;

#[cfg(windows)]
use super::win::WinHandle;

#[cfg(windows)]
pub fn launch_game(
    config: &DebugConfig,
    config_arg: Option<&Path>,
    mod_dirs: &[ResolvedModDir],
) -> Result<()> {
    let enable_ipc = config.auto_hot_reload_mods;
    let ipc = if enable_ipc {
        let server = DebugIpcServer::start()?;
        println!("[MCDK] IPC调试服务器已启动，端口：{}", server.port());
        Some(server)
    } else {
        None
    };

    let command = build_command(config, config_arg);
    let mut command_w = wide_null(OsStr::new(&command));
    let env_block = ipc
        .as_ref()
        .map(|server| build_environment_block(server.port()));

    let mut security = SECURITY_ATTRIBUTES {
        nLength: std::mem::size_of::<SECURITY_ATTRIBUTES>() as u32,
        lpSecurityDescriptor: ptr::null_mut(),
        bInheritHandle: 1,
    };

    let (out_read, out_write) = create_pipe_pair(&mut security)?;
    let (err_read, err_write) = create_pipe_pair(&mut security)?;

    let mut startup: STARTUPINFOW = unsafe { std::mem::zeroed() };
    startup.cb = std::mem::size_of::<STARTUPINFOW>() as u32;
    startup.dwFlags = STARTF_USESTDHANDLES;
    startup.hStdOutput = out_write.raw();
    startup.hStdError = err_write.raw();
    startup.hStdInput = unsafe { GetStdHandle(STD_INPUT_HANDLE) };

    let mut process_info: PROCESS_INFORMATION = unsafe { std::mem::zeroed() };
    let env_ptr = env_block
        .as_ref()
        .map(|block| block.as_ptr().cast_mut().cast())
        .unwrap_or(ptr::null_mut());
    let creation_flags = if env_block.is_some() {
        CREATE_UNICODE_ENVIRONMENT
    } else {
        0
    };

    let ok = unsafe {
        CreateProcessW(
            ptr::null(),
            command_w.as_mut_ptr(),
            ptr::null_mut(),
            ptr::null_mut(),
            1,
            creation_flags,
            env_ptr,
            ptr::null(),
            &startup,
            &mut process_info,
        )
    };
    if ok == 0 {
        let err = io::Error::last_os_error();
        return Err(CliError::Io(io::Error::new(
            err.kind(),
            format!("CreateProcessW failed for command {command:?}: {err}"),
        )));
    }

    drop(out_write);
    drop(err_write);

    let pid = process_info.dwProcessId;
    let stdout_filter = config.include_debug_mod;
    let stderr_filter = config.include_debug_mod;
    let stdout_thread =
        thread::spawn(move || read_pipe(out_read, stdout_filter, log::process_stdout_line));
    let stderr_thread =
        thread::spawn(move || read_pipe(err_read, stderr_filter, log::process_stderr_line));

    let mut hotreload = if config.auto_hot_reload_mods {
        ipc.clone()
            .and_then(|server| HotReloadTask::start(pid, mod_dirs, server))
    } else {
        None
    };

    unsafe { WaitForSingleObject(process_info.hProcess, INFINITE) };

    if let Some(task) = &mut hotreload {
        task.safe_exit();
    }
    if let Some(server) = &ipc {
        server.safe_exit();
    }

    let _ = stdout_thread.join();
    let _ = stderr_thread.join();

    unsafe {
        CloseHandle(process_info.hProcess);
        CloseHandle(process_info.hThread);
    }
    Ok(())
}

#[cfg(not(windows))]
pub fn launch_game(
    _config: &DebugConfig,
    _config_arg: Option<&Path>,
    _mod_dirs: &[ResolvedModDir],
) -> Result<()> {
    Err(CliError::InvalidInput(
        "debug launch is only supported on Windows".to_string(),
    ))
}

#[cfg(windows)]
fn build_command(config: &DebugConfig, config_arg: Option<&Path>) -> String {
    let mut command = String::new();
    command.push('"');
    command.push_str(&config.game_executable_path);
    command.push('"');
    if !config.netease_config.chat_extension {
        command.push_str(" chatExtension=false");
    }
    if let Some(path) = config_arg {
        command.push_str(" config=\"");
        command.push_str(&path.to_string_lossy().replace('\\', "/"));
        command.push('"');
    }
    command
}

#[cfg(windows)]
fn create_pipe_pair(security: &mut SECURITY_ATTRIBUTES) -> Result<(WinHandle, WinHandle)> {
    let mut read: HANDLE = ptr::null_mut();
    let mut write: HANDLE = ptr::null_mut();
    let ok = unsafe { CreatePipe(&mut read, &mut write, security, 0) };
    if ok == 0 {
        return Err(CliError::Io(io::Error::last_os_error()));
    }
    let read = WinHandle::new(read)?;
    let write = WinHandle::new(write)?;
    let ok = unsafe { SetHandleInformation(read.raw(), HANDLE_FLAG_INHERIT, 0) };
    if ok == 0 {
        return Err(CliError::Io(io::Error::last_os_error()));
    }
    Ok((read, write))
}

#[cfg(windows)]
fn read_pipe<F>(pipe: WinHandle, filter_python: bool, process_line: F)
where
    F: Fn(&str) + Send + 'static,
{
    const BUFSZ: usize = 4096;
    let mut line_buffer = LineBuffer::new(filter_python);
    let mut buffer = [0u8; BUFSZ];

    loop {
        let mut bytes_read = 0u32;
        let ok = unsafe {
            ReadFile(
                pipe.raw(),
                buffer.as_mut_ptr().cast(),
                buffer.len() as u32,
                &mut bytes_read,
                ptr::null_mut(),
            )
        };
        if ok == 0 {
            let err = unsafe { GetLastError() };
            if err == ERROR_BROKEN_PIPE {
                line_buffer.flush(|line| process_line(&line));
            }
            break;
        }
        if bytes_read == 0 {
            line_buffer.flush(|line| process_line(&line));
            break;
        }
        line_buffer.append(&buffer[..bytes_read as usize], |line| process_line(&line));
    }
}

#[cfg(windows)]
fn build_environment_block(ipc_port: u16) -> Vec<u16> {
    let mut pairs: Vec<(Vec<u16>, Vec<u16>)> = std::env::vars_os()
        .map(|(key, value)| (key.encode_wide().collect(), value.encode_wide().collect()))
        .collect();
    pairs.push((
        OsStr::new("MCDEV_DEBUG_IPC_PORT").encode_wide().collect(),
        OsStr::new(&ipc_port.to_string()).encode_wide().collect(),
    ));
    pairs.sort_by(|a, b| a.0.cmp(&b.0));

    let mut block = Vec::new();
    for (key, value) in pairs {
        block.extend(key);
        block.push('=' as u16);
        block.extend(value);
        block.push(0);
    }
    block.push(0);
    block
}

#[cfg(windows)]
fn wide_null(value: &OsStr) -> Vec<u16> {
    value.encode_wide().chain(std::iter::once(0)).collect()
}