use base64::{Engine as _, engine::general_purpose::STANDARD};
use clap::Parser;
use smartfs_core::{FsOps, WatchManager};
use smartfs_protocol::*;
use std::collections::HashMap;
use std::io::{self, BufRead, BufWriter, Write as IoWrite};
use std::path::{Path, PathBuf};
use std::os::unix::fs::PermissionsExt;

#[derive(Parser)]
#[command(name = "smartfs-bin", about = "SmartFS Rust filesystem backend")]
struct Cli {
    /// Run in management/IPC mode (JSON over stdin/stdout)
    #[arg(long)]
    management: bool,
}

fn main() {
    let cli = Cli::parse();

    if cli.management {
        run_management_mode();
    } else {
        eprintln!("smartfs-bin: use --management flag for IPC mode");
        std::process::exit(1);
    }
}

/// State for open write streams
struct WriteStreamState {
    writer: BufWriter<std::fs::File>,
    final_path: PathBuf,
    temp_path: Option<PathBuf>,
    mode: Option<u32>,
}

fn run_management_mode() {
    // Send ready event
    let ready = IpcEvent {
        event: "ready".to_string(),
        data: serde_json::json!({
            "version": env!("CARGO_PKG_VERSION"),
            "provider": "rust"
        }),
    };
    send_json(&ready);

    let watch_manager = WatchManager::new();
    let mut write_streams: HashMap<String, WriteStreamState> = HashMap::new();
    let stdin = io::stdin();

    for line in stdin.lock().lines() {
        let line = match line {
            Ok(l) => l,
            Err(_) => break,
        };

        if line.trim().is_empty() {
            continue;
        }

        let request: IpcRequest = match serde_json::from_str(&line) {
            Ok(r) => r,
            Err(e) => {
                eprintln!("smartfs-bin: invalid JSON: {}", e);
                continue;
            }
        };

        let response = dispatch_command(&request, &watch_manager, &mut write_streams);
        send_json(&response);
    }
}

fn dispatch_command(
    req: &IpcRequest,
    watch_manager: &WatchManager,
    write_streams: &mut HashMap<String, WriteStreamState>,
) -> IpcResponse {
    match req.method.as_str() {
        "readFile" => {
            match serde_json::from_value::<ReadFileParams>(req.params.clone()) {
                Ok(params) => match FsOps::read_file(&params) {
                    Ok(result) => IpcResponse::ok(req.id.clone(), result),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "writeFile" => {
            match serde_json::from_value::<WriteFileParams>(req.params.clone()) {
                Ok(params) => match FsOps::write_file(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "appendFile" => {
            match serde_json::from_value::<AppendFileParams>(req.params.clone()) {
                Ok(params) => match FsOps::append_file(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "deleteFile" => {
            match serde_json::from_value::<PathParams>(req.params.clone()) {
                Ok(params) => match FsOps::delete_file(Path::new(&params.path)) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "copyFile" => {
            match serde_json::from_value::<CopyMoveParams>(req.params.clone()) {
                Ok(params) => match FsOps::copy_file(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "moveFile" => {
            match serde_json::from_value::<CopyMoveParams>(req.params.clone()) {
                Ok(params) => match FsOps::move_file(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "fileExists" => {
            match serde_json::from_value::<PathParams>(req.params.clone()) {
                Ok(params) => {
                    let exists = FsOps::file_exists(Path::new(&params.path));
                    IpcResponse::ok(req.id.clone(), serde_json::json!(exists))
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "fileStat" => {
            match serde_json::from_value::<PathParams>(req.params.clone()) {
                Ok(params) => match FsOps::file_stat(Path::new(&params.path)) {
                    Ok(stats) => {
                        IpcResponse::ok(req.id.clone(), serde_json::to_value(&stats).unwrap())
                    }
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "listDirectory" => {
            match serde_json::from_value::<ListDirectoryParams>(req.params.clone()) {
                Ok(params) => match FsOps::list_directory(&params) {
                    Ok(entries) => {
                        IpcResponse::ok(req.id.clone(), serde_json::to_value(&entries).unwrap())
                    }
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "createDirectory" => {
            match serde_json::from_value::<CreateDirectoryParams>(req.params.clone()) {
                Ok(params) => match FsOps::create_directory(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "deleteDirectory" => {
            match serde_json::from_value::<DeleteDirectoryParams>(req.params.clone()) {
                Ok(params) => match FsOps::delete_directory(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "directoryExists" => {
            match serde_json::from_value::<PathParams>(req.params.clone()) {
                Ok(params) => {
                    let exists = FsOps::directory_exists(Path::new(&params.path));
                    IpcResponse::ok(req.id.clone(), serde_json::json!(exists))
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "directoryStat" => {
            match serde_json::from_value::<PathParams>(req.params.clone()) {
                Ok(params) => match FsOps::directory_stat(Path::new(&params.path)) {
                    Ok(stats) => {
                        IpcResponse::ok(req.id.clone(), serde_json::to_value(&stats).unwrap())
                    }
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "watch" => {
            match serde_json::from_value::<WatchParams>(req.params.clone()) {
                Ok(params) => {
                    match watch_manager.add_watch(
                        params.id,
                        &params.path,
                        params.recursive.unwrap_or(false),
                    ) {
                        Ok(()) => IpcResponse::ok_void(req.id.clone()),
                        Err(e) => IpcResponse::err(req.id.clone(), e),
                    }
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "unwatchAll" => {
            match watch_manager.remove_all() {
                Ok(()) => IpcResponse::ok_void(req.id.clone()),
                Err(e) => IpcResponse::err(req.id.clone(), e),
            }
        }

        "batch" => {
            match serde_json::from_value::<BatchParams>(req.params.clone()) {
                Ok(params) => {
                    let results = FsOps::batch(&params);
                    IpcResponse::ok(req.id.clone(), serde_json::to_value(&results).unwrap())
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "executeTransaction" => {
            match serde_json::from_value::<TransactionParams>(req.params.clone()) {
                Ok(params) => match FsOps::execute_transaction(&params) {
                    Ok(()) => IpcResponse::ok_void(req.id.clone()),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "normalizePath" => {
            match serde_json::from_value::<NormalizePathParams>(req.params.clone()) {
                Ok(params) => {
                    let result = FsOps::normalize_path(&params.path);
                    IpcResponse::ok(req.id.clone(), serde_json::json!(result))
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "joinPath" => {
            match serde_json::from_value::<JoinPathParams>(req.params.clone()) {
                Ok(params) => {
                    let result = FsOps::join_path(&params.segments);
                    IpcResponse::ok(req.id.clone(), serde_json::json!(result))
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "readFileStream" => {
            match serde_json::from_value::<ReadFileStreamParams>(req.params.clone()) {
                Ok(params) => match FsOps::read_file_stream(&req.id, &params) {
                    Ok(total) => IpcResponse::ok(req.id.clone(), serde_json::json!({ "totalBytes": total })),
                    Err(e) => IpcResponse::err(req.id.clone(), e),
                },
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "writeStreamBegin" => {
            match serde_json::from_value::<WriteStreamBeginParams>(req.params.clone()) {
                Ok(params) => {
                    let final_path = PathBuf::from(&params.path);

                    // Ensure parent directory exists
                    if let Some(parent) = final_path.parent() {
                        if !parent.exists() {
                            if let Err(e) = std::fs::create_dir_all(parent) {
                                return IpcResponse::err(req.id.clone(), format!("writeStreamBegin mkdir: {}", e));
                            }
                        }
                    }

                    let (write_path, temp_path) = if params.atomic.unwrap_or(false) {
                        let temp = final_path.with_extension(format!(
                            "tmp.{}",
                            std::time::SystemTime::now()
                                .duration_since(std::time::SystemTime::UNIX_EPOCH)
                                .unwrap()
                                .as_nanos()
                        ));
                        (temp.clone(), Some(temp))
                    } else {
                        (final_path.clone(), None)
                    };

                    match std::fs::File::create(&write_path) {
                        Ok(file) => {
                            let stream_id = format!("ws_{}", req.id);
                            write_streams.insert(stream_id.clone(), WriteStreamState {
                                writer: BufWriter::new(file),
                                final_path,
                                temp_path,
                                mode: params.mode,
                            });
                            IpcResponse::ok(req.id.clone(), serde_json::json!({ "streamId": stream_id }))
                        }
                        Err(e) => IpcResponse::err(req.id.clone(), format!("writeStreamBegin create: {}", e)),
                    }
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "writeStreamChunk" => {
            match serde_json::from_value::<WriteStreamChunkParams>(req.params.clone()) {
                Ok(params) => {
                    let stream = match write_streams.get_mut(&params.stream_id) {
                        Some(s) => s,
                        None => return IpcResponse::err(req.id.clone(), format!("unknown streamId: {}", params.stream_id)),
                    };

                    // Write data if non-empty
                    if !params.data.is_empty() {
                        match STANDARD.decode(&params.data) {
                            Ok(bytes) => {
                                if let Err(e) = stream.writer.write_all(&bytes) {
                                    write_streams.remove(&params.stream_id);
                                    return IpcResponse::err(req.id.clone(), format!("writeStreamChunk write: {}", e));
                                }
                            }
                            Err(e) => {
                                write_streams.remove(&params.stream_id);
                                return IpcResponse::err(req.id.clone(), format!("writeStreamChunk decode: {}", e));
                            }
                        }
                    }

                    if params.last {
                        // Finalize: flush, fsync, set mode, rename if atomic, fsync parent
                        let state = write_streams.remove(&params.stream_id).unwrap();
                        let mut writer = state.writer;

                        if let Err(e) = writer.flush() {
                            return IpcResponse::err(req.id.clone(), format!("writeStreamChunk flush: {}", e));
                        }

                        // Get inner file for fsync
                        let file = match writer.into_inner() {
                            Ok(f) => f,
                            Err(e) => {
                                return IpcResponse::err(req.id.clone(), format!("writeStreamChunk into_inner: {}", e.error()));
                            }
                        };
                        if let Err(e) = file.sync_all() {
                            return IpcResponse::err(req.id.clone(), format!("writeStreamChunk fsync: {}", e));
                        }
                        drop(file);

                        // Set mode if requested
                        if let Some(mode) = state.mode {
                            let write_path = state.temp_path.as_ref().unwrap_or(&state.final_path);
                            let _ = std::fs::set_permissions(write_path, std::fs::Permissions::from_mode(mode));
                        }

                        // Rename if atomic
                        if let Some(ref temp_path) = state.temp_path {
                            if let Err(e) = std::fs::rename(temp_path, &state.final_path) {
                                let _ = std::fs::remove_file(temp_path);
                                return IpcResponse::err(req.id.clone(), format!("writeStreamChunk rename: {}", e));
                            }
                        }

                        // Fsync parent
                        if let Some(parent) = state.final_path.parent() {
                            let _ = std::fs::File::open(parent).and_then(|f| f.sync_all());
                        }
                    }

                    IpcResponse::ok_void(req.id.clone())
                }
                Err(e) => IpcResponse::err(req.id.clone(), format!("invalid params: {}", e)),
            }
        }

        "ping" => IpcResponse::ok(req.id.clone(), serde_json::json!({ "pong": true })),

        other => IpcResponse::err(req.id.clone(), format!("unknown method: {}", other)),
    }
}

fn send_json<T: serde::Serialize>(value: &T) {
    if let Ok(json) = serde_json::to_string(value) {
        let stdout = io::stdout();
        let mut out = stdout.lock();
        let _ = writeln!(out, "{}", json);
        let _ = out.flush();
    }
}