use clap::Parser;
use futures_util::{SinkExt, StreamExt};
use std::os::unix::net::UnixStream as StdUnixStream;
use std::path::PathBuf;
use tokio::net::UnixStream as TokioUnixStream;

use crate::{
    cli::{
        common::erroneous_server_response,
        database_command,
        mysql_admutils_compatibility::{
            common::trim_to_32_chars,
            error_messages::{
                format_show_database_error_message, handle_create_database_error,
                handle_drop_database_error,
            },
        },
    },
    core::{
        bootstrap::bootstrap_server_connection_and_drop_privileges,
        protocol::{
            create_client_to_server_message_stream, ClientToServerMessageStream,
            GetDatabasesPrivilegeDataError, Request, Response,
        },
    },
    server::sql::database_privilege_operations::DatabasePrivilegeRow,
};

const HELP_DB_PERM: &str = r#"
Edit permissions for the DATABASE(s). Running this command will
spawn the editor stored in the $EDITOR environment variable.
(pico will be used if the variable is unset)

The file should contain one line per user, starting with the
username and followed by ten Y/N-values seperated by whitespace.
Lines starting with # are ignored.

The Y/N-values corresponds to the following mysql privileges:
  Select     - Enables use of SELECT
  Insert     - Enables use of INSERT
  Update     - Enables use of UPDATE
  Delete     - Enables use of DELETE
  Create     - Enables use of CREATE TABLE
  Drop       - Enables use of DROP TABLE
  Alter      - Enables use of ALTER TABLE
  Index      - Enables use of CREATE INDEX and DROP INDEX
  Temp       - Enables use of CREATE TEMPORARY TABLE
  Lock       - Enables use of LOCK TABLE
  References - Enables use of REFERENCES
"#;

#[derive(Parser)]
pub struct Args {
    #[command(subcommand)]
    pub command: Option<Command>,

    /// Path to the socket of the server, if it already exists.
    #[arg(
        short,
        long,
        value_name = "PATH",
        global = true,
        hide_short_help = true
    )]
    server_socket_path: Option<PathBuf>,

    /// Config file to use for the server.
    #[arg(
        short,
        long,
        value_name = "PATH",
        global = true,
        hide_short_help = true
    )]
    config: Option<PathBuf>,

    /// Print help for the 'editperm' subcommand.
    #[arg(long, global = true)]
    pub help_editperm: bool,
}

// NOTE: mysql-dbadm explicitly calls privileges "permissions".
//       This is something we're trying to move away from.
//       See https://git.pvv.ntnu.no/Projects/mysqladm-rs/issues/29

/// Create, drop or edit permissions for the DATABASE(s),
/// as determined by the COMMAND.
///
/// This is a compatibility layer for the mysql-dbadm command.
/// Please consider using the newer mysqladm command instead.
#[derive(Parser)]
#[command(version, about, disable_help_subcommand = true, verbatim_doc_comment)]
pub enum Command {
    /// create the DATABASE(s).
    Create(CreateArgs),

    /// delete the DATABASE(s).
    Drop(DatabaseDropArgs),

    /// give information about the DATABASE(s), or, if
    /// none are given, all the ones you own.
    Show(DatabaseShowArgs),

    // TODO: make this output more verbatim_doc_comment-like,
    //       without messing up the indentation.
    /// change permissions for the DATABASE(s). Your
    /// favorite editor will be started, allowing you
    /// to make changes to the permission table.
    /// Run 'mysql-dbadm --help-editperm' for more
    /// information.
    Editperm(EditPermArgs),
}

#[derive(Parser)]
pub struct CreateArgs {
    /// The name of the DATABASE(s) to create.
    #[arg(num_args = 1..)]
    name: Vec<String>,
}

#[derive(Parser)]
pub struct DatabaseDropArgs {
    /// The name of the DATABASE(s) to drop.
    #[arg(num_args = 1..)]
    name: Vec<String>,
}

#[derive(Parser)]
pub struct DatabaseShowArgs {
    /// The name of the DATABASE(s) to show.
    #[arg(num_args = 0..)]
    name: Vec<String>,
}

#[derive(Parser)]
pub struct EditPermArgs {
    /// The name of the DATABASE to edit permissions for.
    pub database: String,
}

pub fn main() -> anyhow::Result<()> {
    let args: Args = Args::parse();

    if args.help_editperm {
        println!("{}", HELP_DB_PERM);
        return Ok(());
    }

    let server_connection =
        bootstrap_server_connection_and_drop_privileges(args.server_socket_path, args.config)?;

    let command = match args.command {
        Some(command) => command,
        None => {
            println!(
                "Try `{} --help' for more information.",
                std::env::args().next().unwrap_or("mysql-dbadm".to_string())
            );
            return Ok(());
        }
    };

    tokio_run_command(command, server_connection)?;

    Ok(())
}

fn tokio_run_command(command: Command, server_connection: StdUnixStream) -> anyhow::Result<()> {
    tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap()
        .block_on(async {
            let tokio_socket = TokioUnixStream::from_std(server_connection)?;
            let message_stream = create_client_to_server_message_stream(tokio_socket);
            match command {
                Command::Create(args) => create_databases(args, message_stream).await,
                Command::Drop(args) => drop_databases(args, message_stream).await,
                Command::Show(args) => show_databases(args, message_stream).await,
                Command::Editperm(args) => {
                    let edit_privileges_args = database_command::DatabaseEditPrivsArgs {
                        name: Some(args.database),
                        privs: vec![],
                        json: false,
                        // TODO: use this to mimic the old editor-finding logic
                        editor: None,
                        yes: false,
                    };

                    database_command::edit_database_privileges(edit_privileges_args, message_stream)
                        .await
                }
            }
        })
}

async fn create_databases(
    args: CreateArgs,
    mut server_connection: ClientToServerMessageStream,
) -> anyhow::Result<()> {
    let database_names = args
        .name
        .iter()
        .map(|name| trim_to_32_chars(name))
        .collect();

    let message = Request::CreateDatabases(database_names);
    server_connection.send(message).await?;

    let result = match server_connection.next().await {
        Some(Ok(Response::CreateDatabases(result))) => result,
        response => return erroneous_server_response(response),
    };

    server_connection.send(Request::Exit).await?;

    for (name, result) in result {
        match result {
            Ok(()) => println!("Database {} created.", name),
            Err(err) => handle_create_database_error(err, &name),
        }
    }

    Ok(())
}

async fn drop_databases(
    args: DatabaseDropArgs,
    mut server_connection: ClientToServerMessageStream,
) -> anyhow::Result<()> {
    let database_names = args
        .name
        .iter()
        .map(|name| trim_to_32_chars(name))
        .collect();

    let message = Request::DropDatabases(database_names);
    server_connection.send(message).await?;

    let result = match server_connection.next().await {
        Some(Ok(Response::DropDatabases(result))) => result,
        response => return erroneous_server_response(response),
    };

    server_connection.send(Request::Exit).await?;

    for (name, result) in result {
        match result {
            Ok(()) => println!("Database {} dropped.", name),
            Err(err) => handle_drop_database_error(err, &name),
        }
    }

    Ok(())
}

async fn show_databases(
    args: DatabaseShowArgs,
    mut server_connection: ClientToServerMessageStream,
) -> anyhow::Result<()> {
    let database_names: Vec<String> = args
        .name
        .iter()
        .map(|name| trim_to_32_chars(name))
        .collect();

    let message = if database_names.is_empty() {
        let message = Request::ListDatabases;
        server_connection.send(message).await?;
        let response = server_connection.next().await;
        let databases = match response {
            Some(Ok(Response::ListAllDatabases(databases))) => databases.unwrap_or(vec![]),
            response => return erroneous_server_response(response),
        };

        Request::ListPrivileges(Some(databases))
    } else {
        Request::ListPrivileges(Some(database_names))
    };
    server_connection.send(message).await?;

    let response = server_connection.next().await;

    server_connection.send(Request::Exit).await?;

    // NOTE: mysql-dbadm show has a quirk where valid database names
    //       for non-existent databases will report with no users.
    let results: Vec<Result<(String, Vec<DatabasePrivilegeRow>), String>> = match response {
        Some(Ok(Response::ListPrivileges(result))) => result
            .into_iter()
            .map(|(name, rows)| match rows.map(|rows| (name.clone(), rows)) {
                Ok(rows) => Ok(rows),
                Err(GetDatabasesPrivilegeDataError::DatabaseDoesNotExist) => Ok((name, vec![])),
                Err(err) => Err(format_show_database_error_message(err, &name)),
            })
            .collect(),
        response => return erroneous_server_response(response),
    };

    results.into_iter().try_for_each(|result| match result {
        Ok((name, rows)) => print_db_privs(&name, rows),
        Err(err) => {
            eprintln!("{}", err);
            Ok(())
        }
    })?;

    Ok(())
}

#[inline]
fn yn(value: bool) -> &'static str {
    if value {
        "Y"
    } else {
        "N"
    }
}

fn print_db_privs(name: &str, rows: Vec<DatabasePrivilegeRow>) -> anyhow::Result<()> {
    println!(
        concat!(
            "Database '{}':\n",
            "# User                Select  Insert  Update  Delete  Create   Drop   Alter   Index    Temp    Lock  References\n",
            "# ----------------    ------  ------  ------  ------  ------   ----   -----   -----    ----    ----  ----------"
        ),
        name,
    );
    if rows.is_empty() {
        println!("# (no permissions currently granted to any users)");
    } else {
        for privilege in rows {
            println!(
                "  {:<16}      {:<7} {:<7} {:<7} {:<7} {:<7} {:<7} {:<7} {:<7} {:<7} {:<7} {}",
                privilege.user,
                yn(privilege.select_priv),
                yn(privilege.insert_priv),
                yn(privilege.update_priv),
                yn(privilege.delete_priv),
                yn(privilege.create_priv),
                yn(privilege.drop_priv),
                yn(privilege.alter_priv),
                yn(privilege.index_priv),
                yn(privilege.create_tmp_table_priv),
                yn(privilege.lock_tables_priv),
                yn(privilege.references_priv)
            );
        }
    }

    Ok(())
}