use std::net::SocketAddr;
use std::path::PathBuf;
use std::process::ExitCode;
use std::sync::Arc;

use tokio::net::TcpListener;
use yoi_workspace_server::{
    SqliteWorkspaceStore, WORKSPACE_BACKEND_CONFIG_TEMPLATE, WorkspaceBackendConfigFile,
    WorkspaceIdentity, serve,
};

#[derive(Debug)]
enum Command {
    Serve(ServeOptions),
    Init(InitOptions),
    ConfigDefault,
    ConfigDiff(WorkspacePathOptions),
    Help,
}

#[derive(Debug)]
struct ServeOptions {
    workspace: PathBuf,
    db: Option<PathBuf>,
    frontend: Option<PathBuf>,
    listen: Option<SocketAddr>,
}

#[derive(Debug)]
struct InitOptions {
    workspace: PathBuf,
}

#[derive(Debug)]
struct WorkspacePathOptions {
    workspace: PathBuf,
}

#[derive(Debug)]
struct CliError(String);

impl std::fmt::Display for CliError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(&self.0)
    }
}

impl std::error::Error for CliError {}

#[tokio::main]
async fn main() -> ExitCode {
    match run().await {
        Ok(()) => ExitCode::SUCCESS,
        Err(error) => {
            eprintln!("yoi-workspace-server: {error}");
            ExitCode::FAILURE
        }
    }
}

async fn run() -> Result<(), Box<dyn std::error::Error>> {
    let args = std::env::args().skip(1).collect::<Vec<_>>();
    match parse_command(&args)? {
        Command::Serve(options) => run_serve(options).await,
        Command::Init(options) => run_init(options),
        Command::ConfigDefault => run_config_default(),
        Command::ConfigDiff(options) => run_config_diff(options),
        Command::Help => Ok(()),
    }
}

fn parse_command(args: &[String]) -> Result<Command, CliError> {
    let Some((command, rest)) = args.split_first() else {
        print_help();
        return Ok(Command::Help);
    };

    match command.as_str() {
        "init" => {
            if rest.iter().any(|arg| arg == "--help" || arg == "-h") {
                print_init_help();
                return Ok(Command::Help);
            }
            Ok(Command::Init(parse_init_options(rest)?))
        }
        "config" => parse_config_command(rest),
        "serve" => {
            if rest.iter().any(|arg| arg == "--help" || arg == "-h") {
                print_serve_help();
                return Ok(Command::Help);
            }
            Ok(Command::Serve(parse_serve_options(rest)?))
        }
        "--help" | "-h" => {
            print_help();
            Ok(Command::Help)
        }
        other => Err(CliError(format!(
            "unknown command `{other}`; expected `init`, `config`, or `serve`"
        ))),
    }
}

fn run_init(options: InitOptions) -> Result<(), Box<dyn std::error::Error>> {
    let identity = WorkspaceIdentity::load_or_init(&options.workspace)?;
    WorkspaceBackendConfigFile::ensure_local_config_for_workspace(&options.workspace)?;
    eprintln!(
        "yoi-workspace-server: initialized workspace `{}` ({})",
        options.workspace.display(),
        identity.workspace_id
    );
    Ok(())
}

fn run_config_default() -> Result<(), Box<dyn std::error::Error>> {
    print!("{WORKSPACE_BACKEND_CONFIG_TEMPLATE}");
    Ok(())
}

fn run_config_diff(options: WorkspacePathOptions) -> Result<(), Box<dyn std::error::Error>> {
    let diff = WorkspaceBackendConfigFile::local_config_diff_for_workspace(&options.workspace)?;
    print!("{}", diff.text);
    Ok(())
}

async fn run_serve(options: ServeOptions) -> Result<(), Box<dyn std::error::Error>> {
    let identity = WorkspaceIdentity::load_required(&options.workspace)?;
    let config_file = WorkspaceBackendConfigFile::load_for_workspace(&options.workspace)?;
    let mut resolved = config_file.resolve(&options.workspace, identity)?;
    if let Some(db) = options.db {
        resolved = resolved.with_database_path(db);
    }
    if let Some(frontend) = options.frontend {
        resolved = resolved.with_static_assets_dir(Some(frontend));
    }
    if let Some(listen) = options.listen {
        resolved = resolved.with_listen(listen);
    }

    if let Some(parent) = resolved.database_path.parent() {
        tokio::fs::create_dir_all(parent).await?;
    }

    let store = Arc::new(SqliteWorkspaceStore::open(&resolved.database_path)?);
    let listener = TcpListener::bind(resolved.listen).await?;
    eprintln!(
        "yoi-workspace-server: serving workspace `{}` on http://{}",
        options.workspace.display(),
        listener.local_addr()?
    );
    serve(resolved.server, store, listener).await?;
    Ok(())
}

fn parse_config_command(args: &[String]) -> Result<Command, CliError> {
    let Some((subcommand, rest)) = args.split_first() else {
        print_config_help();
        return Ok(Command::Help);
    };
    match subcommand.as_str() {
        "default" => {
            if rest.iter().any(|arg| arg == "--help" || arg == "-h") {
                print_config_help();
                return Ok(Command::Help);
            }
            if !rest.is_empty() {
                return Err(CliError(
                    "config default does not accept options".to_string(),
                ));
            }
            Ok(Command::ConfigDefault)
        }
        "diff" => {
            if rest.iter().any(|arg| arg == "--help" || arg == "-h") {
                print_config_help();
                return Ok(Command::Help);
            }
            Ok(Command::ConfigDiff(parse_workspace_path_options(rest)?))
        }
        "--help" | "-h" => {
            print_config_help();
            Ok(Command::Help)
        }
        other => Err(CliError(format!(
            "unknown config subcommand `{other}`; expected `default` or `diff`"
        ))),
    }
}

fn parse_workspace_path_options(args: &[String]) -> Result<WorkspacePathOptions, CliError> {
    let mut workspace = std::env::current_dir()
        .map_err(|error| CliError(format!("failed to read current dir: {error}")))?;
    let mut iter = args.iter();
    while let Some(arg) = iter.next() {
        match arg.as_str() {
            "--workspace" => {
                let value = iter
                    .next()
                    .ok_or_else(|| CliError("--workspace requires a path".to_string()))?;
                workspace = PathBuf::from(value);
            }
            value if value.starts_with("--workspace=") => {
                workspace = PathBuf::from(value_after_equals(arg, "--workspace")?);
            }
            other => return Err(CliError(format!("unknown workspace option `{other}`"))),
        }
    }
    let workspace = workspace
        .canonicalize()
        .map_err(|error| CliError(format!("failed to canonicalize workspace: {error}")))?;
    Ok(WorkspacePathOptions { workspace })
}

fn parse_init_options(args: &[String]) -> Result<InitOptions, CliError> {
    let mut workspace = std::env::current_dir()
        .map_err(|error| CliError(format!("failed to read current dir: {error}")))?;
    let mut iter = args.iter();
    while let Some(arg) = iter.next() {
        match arg.as_str() {
            "--workspace" => {
                let value = iter
                    .next()
                    .ok_or_else(|| CliError("--workspace requires a path".to_string()))?;
                workspace = PathBuf::from(value);
            }
            value if value.starts_with("--workspace=") => {
                workspace = PathBuf::from(value_after_equals(arg, "--workspace")?);
            }
            other => return Err(CliError(format!("unknown init option `{other}`"))),
        }
    }

    let workspace = workspace
        .canonicalize()
        .map_err(|error| CliError(format!("failed to canonicalize workspace: {error}")))?;
    Ok(InitOptions { workspace })
}

fn parse_serve_options(args: &[String]) -> Result<ServeOptions, CliError> {
    let mut workspace = std::env::current_dir()
        .map_err(|error| CliError(format!("failed to resolve current directory: {error}")))?;
    let mut db = None;
    let mut frontend = None;
    let mut listen = None;

    let mut index = 0;
    while index < args.len() {
        let arg = &args[index];
        match arg.as_str() {
            "--workspace" => {
                index += 1;
                let value = args
                    .get(index)
                    .ok_or_else(|| CliError("--workspace requires a value".to_string()))?;
                workspace = PathBuf::from(value);
            }
            "--db" => {
                index += 1;
                let value = args
                    .get(index)
                    .ok_or_else(|| CliError("--db requires a value".to_string()))?;
                db = Some(PathBuf::from(value));
            }
            "--frontend" => {
                index += 1;
                let value = args
                    .get(index)
                    .ok_or_else(|| CliError("--frontend requires a value".to_string()))?;
                frontend = Some(PathBuf::from(value));
            }
            "--listen" => {
                index += 1;
                let value = args
                    .get(index)
                    .ok_or_else(|| CliError("--listen requires a value".to_string()))?;
                listen = Some(parse_listen(value)?);
            }
            _ if arg.starts_with("--workspace=") => {
                workspace = PathBuf::from(value_after_equals(arg, "--workspace")?);
            }
            _ if arg.starts_with("--db=") => {
                db = Some(PathBuf::from(value_after_equals(arg, "--db")?));
            }
            _ if arg.starts_with("--frontend=") => {
                frontend = Some(PathBuf::from(value_after_equals(arg, "--frontend")?));
            }
            _ if arg.starts_with("--listen=") => {
                listen = Some(parse_listen(value_after_equals(arg, "--listen")?)?);
            }
            _ if arg.starts_with('-') => {
                return Err(CliError(format!("unknown serve option `{arg}`")));
            }
            _ => {
                return Err(CliError(format!(
                    "unexpected positional argument `{arg}`; use --workspace <PATH>"
                )));
            }
        }
        index += 1;
    }

    let workspace = workspace.canonicalize().map_err(|error| {
        CliError(format!(
            "failed to canonicalize workspace `{}`: {error}",
            workspace.display()
        ))
    })?;

    Ok(ServeOptions {
        workspace,
        db,
        frontend,
        listen,
    })
}

fn value_after_equals<'a>(arg: &'a str, flag: &str) -> Result<&'a str, CliError> {
    let value = arg
        .strip_prefix(flag)
        .and_then(|rest| rest.strip_prefix('='))
        .unwrap_or_default();
    if value.is_empty() {
        return Err(CliError(format!("{flag} requires a value")));
    }
    Ok(value)
}

fn parse_listen(value: &str) -> Result<SocketAddr, CliError> {
    value
        .parse()
        .map_err(|_| CliError(format!("invalid --listen address `{value}`")))
}

fn print_help() {
    println!(
        "yoi-workspace-server\n\nUsage:\n  yoi-workspace-server init [OPTIONS]\n  yoi-workspace-server config <COMMAND> [OPTIONS]\n  yoi-workspace-server serve [OPTIONS]\n\nOptions:\n  -h, --help    Print help"
    );
}

fn print_init_help() {
    println!(
        "yoi-workspace-server init\n\nUsage:\n  yoi-workspace-server init [OPTIONS]\n\nDescription:\n  Initializes a Workspace identity and copies the packaged Backend config template to .yoi/workspace-backend.local.toml. Does not create Backend data stores.\n\nOptions:\n      --workspace <PATH>  Workspace root to initialize (defaults to cwd)\n  -h, --help              Print help"
    );
}

fn print_config_help() {
    println!(
        "yoi-workspace-server config\n\nUsage:\n  yoi-workspace-server config default\n  yoi-workspace-server config diff [OPTIONS]\n\nDescription:\n  Prints the packaged Workspace Backend config template or compares it with the workspace-local config.\n\nOptions for diff:\n      --workspace <PATH>  Workspace root (defaults to cwd)\n  -h, --help              Print help"
    );
}

fn print_serve_help() {
    println!(
        "yoi-workspace-server serve\n\nUsage:\n  yoi-workspace-server serve [OPTIONS]\n\nDescription:\n  Serves an already initialized Workspace. Run `yoi workspace init` first.\n\nOptions:\n      --workspace <PATH>  Workspace root containing .yoi project records (defaults to cwd)\n      --db <PATH>         SQLite database path (legacy dev override)\n      --frontend <PATH>   Static SPA build directory to serve (legacy dev override)\n      --listen <ADDR>     Listen address (legacy dev override; default 127.0.0.1:8787)\n  -h, --help              Print help"
    );
}

#[cfg(test)]
mod tests {
    use super::*;
    use yoi_workspace_server::{
        WORKSPACE_BACKEND_CONFIG_RELATIVE_PATH, WORKSPACE_BACKEND_CONFIG_TEMPLATE,
        WORKSPACE_IDENTITY_RELATIVE_PATH,
    };

    #[test]
    fn parse_init_defaults_workspace_to_cwd_or_flag() {
        let temp = tempfile::tempdir().unwrap();
        let args = vec!["--workspace".to_string(), temp.path().display().to_string()];
        let options = parse_init_options(&args).unwrap();
        assert_eq!(options.workspace, temp.path().canonicalize().unwrap());
    }

    #[test]
    fn init_creates_identity_and_local_config_only() {
        let temp = tempfile::tempdir().unwrap();
        run_init(InitOptions {
            workspace: temp.path().canonicalize().unwrap(),
        })
        .unwrap();

        assert!(temp.path().join(WORKSPACE_IDENTITY_RELATIVE_PATH).exists());
        let local_config_path = temp.path().join(WORKSPACE_BACKEND_CONFIG_RELATIVE_PATH);
        assert!(local_config_path.exists());
        assert_eq!(
            std::fs::read_to_string(local_config_path).unwrap(),
            WORKSPACE_BACKEND_CONFIG_TEMPLATE
        );
        assert!(
            !temp
                .path()
                .join(".yoi/workspace-backend.default.toml")
                .exists()
        );
        assert!(!temp.path().join(".yoi/workspace.db").exists());
        assert!(!temp.path().join(".yoi/embedded-runtime").exists());
    }
}