use std::{

    collections::{BTreeMap, BTreeSet},

    io::IsTerminal,

};

use anyhow::Context;

use clap::{Args, Parser};

use clap_complete::ArgValueCompleter;

use dialoguer::{Confirm, Editor};

use futures_util::SinkExt;

use itertools::Itertools;

use nix::unistd::{User, getuid};

use tokio_stream::StreamExt;

use crate::{

    client::commands::{erroneous_server_response, print_authorization_owner_hint},

    core::{

        completion::{mysql_database_completer, mysql_user_completer},

        database_privileges::{

            DatabasePrivilegeEdit, DatabasePrivilegeEditEntry, DatabasePrivilegeRow,

            DatabasePrivilegeRowDiff, DatabasePrivilegesDiff, create_or_modify_privilege_rows,

            diff_privileges, display_privilege_diffs, generate_editor_content_from_privilege_data,

            parse_privilege_data_from_editor_content, reduce_privilege_diffs,

        },

        protocol::{

            ClientToServerMessageStream, ListDatabasesError, ListUsersError,

            ModifyDatabasePrivilegesError, Request, Response,

            print_modify_database_privileges_output_status, request_validation::ValidationError,

        },

        types::{MySQLDatabase, MySQLUser},

    },

};

#[derive(Parser, Debug, Clone)]

pub struct EditPrivsArgs {

    /// The privileges to set, grant or revoke, in the format `DATABASE:USER:[+-]PRIVILEGES`

    ///

    /// This option allows for changing privileges for multiple databases and users in batch.

    ///

    /// This can not be used together with the positional `DB_NAME`, `USER_NAME` and `PRIVILEGES` arguments.

    #[arg(

      short,

      long,

      value_name = "DB_NAME:USER_NAME:[+-]PRIVILEGES",

      num_args = 0..,

      value_parser = DatabasePrivilegeEditEntry::parse_from_str,

      conflicts_with("single_priv"),

    )]

    pub privs: Vec<DatabasePrivilegeEditEntry>,

    #[command(flatten)]

    pub single_priv: Option<SinglePrivilegeEditArgs>,

    /// Print the information as JSON

    #[arg(short, long)]

    pub json: bool,

    /// Specify the text editor to use for editing privileges

    #[arg(

      short,

      long,

      value_name = "COMMAND",

      value_hint = clap::ValueHint::CommandString,

    )]

    pub editor: Option<String>,

    /// Disable interactive confirmation before saving changes

    #[arg(short, long)]

    pub yes: bool,

}

#[derive(Args, Debug, Clone)]

pub struct SinglePrivilegeEditArgs {

    /// The `MySQL` database to edit privileges for

    #[cfg_attr(not(feature = "suid-sgid-mode"), arg(add = ArgValueCompleter::new(mysql_database_completer)))]

    #[arg(

        value_name = "DB_NAME",

        requires = "user_name",

        requires = "single_priv"

    )]

    pub db_name: Option<MySQLDatabase>,

    /// The `MySQL` database to edit privileges for

    #[cfg_attr(not(feature = "suid-sgid-mode"), arg(add = ArgValueCompleter::new(mysql_user_completer)))]

    #[arg(value_name = "USER_NAME")]

    pub user_name: Option<MySQLUser>,

    /// The privileges to set, grant or revoke

    #[arg(

      allow_hyphen_values = true,

      value_name = "[+-]PRIVILEGES",

      value_parser = DatabasePrivilegeEdit::parse_from_str,

    )]

    pub single_priv: Option<DatabasePrivilegeEdit>,

}

async fn users_exist(

    server_connection: &mut ClientToServerMessageStream,

    privilege_diff: &BTreeSet<DatabasePrivilegesDiff>,

) -> anyhow::Result<BTreeMap<MySQLUser, Result<(), ListUsersError>>> {

    let user_list = privilege_diff

        .iter()

        .collect();

    let message = Request::ListUsers(Some(user_list));

    server_connection.send(message).await?;

    let result = match server_connection.next().await {

        Some(Ok(Response::ListUsers(user_map))) => user_map,

        response => {

            erroneous_server_response(response)?;

            // Unreachable, but needed to satisfy the type checker

            BTreeMap::new()

        }

    };

    let result = result

        .into_iter()

        .collect();

    Ok(result)

}

async fn databases_exist(

    server_connection: &mut ClientToServerMessageStream,

    privilege_diff: &BTreeSet<DatabasePrivilegesDiff>,

) -> anyhow::Result<BTreeMap<MySQLDatabase, Result<(), ListDatabasesError>>> {

    let database_list = privilege_diff

        .iter()

        .collect();

    let message = Request::ListDatabases(Some(database_list));

    server_connection.send(message).await?;

    let result = match server_connection.next().await {

        Some(Ok(Response::ListDatabases(database_map))) => database_map,

        response => {

            erroneous_server_response(response)?;

            // Unreachable, but needed to satisfy the type checker

            BTreeMap::new()

        }

    };

    let result = result

        .into_iter()

        .collect();

    Ok(result)

}

// TODO: reduce the complexity of this function

    let message = Request::ListPrivileges(use_database.clone().map(|db| vec![db]));

    server_connection.send(message).await?;

    debug_assert!(args.privs.is_empty() ^ args.single_priv.is_none());

    let privs = if let Some(single_priv_entry) = &args.single_priv {

        let database = single_priv_entry.db_name.clone().ok_or_else(|| {

            anyhow::anyhow!(

                "DB_NAME must be specified when editing privileges in single privilege mode"

            )

        })?;

        let user = single_priv_entry.user_name.clone().ok_or_else(|| {

            anyhow::anyhow!(

                "USER_NAME must be specified when DB_NAME is specified in single privilege mode"

            )

        })?;

        let privilege_edit = single_priv_entry.single_priv.clone().ok_or_else(|| {

            anyhow::anyhow!(

                "PRIVILEGES must be specified when DB_NAME is specified in single privilege mode"

            )

        })?;

        vec![DatabasePrivilegeEditEntry {

            database,

            user,

            privilege_edit,

        }]

    } else {

        args.privs.clone()

    };

    let existing_privilege_rows = match server_connection.next().await {

        Some(Ok(Response::ListPrivileges(databases))) => databases

            .into_iter()

                }

            .flatten()

            .collect::<Vec<_>>(),

        Some(Ok(Response::ListAllPrivileges(privilege_rows))) => match privilege_rows {

            Ok(list) => list

                .into_iter()

                .collect(),

            Err(err) => {

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

                return Err(anyhow::anyhow!(err.to_error_message())

                    .context("Failed to list database privileges"));

            }

        },

        response => return erroneous_server_response(response),

    };

    let diffs: BTreeSet<DatabasePrivilegesDiff> = if privs.is_empty() {

        if !std::io::stdin().is_terminal() {

            anyhow::bail!(

                "Cannot launch editor in non-interactive mode. Please provide privileges via command line arguments."

            );

        }

        let privileges_to_change =

            edit_privileges_with_editor(&existing_privilege_rows, use_database.as_ref())?;

        diff_privileges(&existing_privilege_rows, &privileges_to_change)

    } else {

        let privileges_to_change = parse_privilege_tables(&privs)?;

        create_or_modify_privilege_rows(&existing_privilege_rows, &privileges_to_change)?

    };

    let database_existence_map = databases_exist(&mut server_connection, &diffs).await?;

    let user_existence_map = users_exist(&mut server_connection, &diffs).await?;

    let diffs = reduce_privilege_diffs(&existing_privilege_rows, diffs)?

        .into_iter()

        .collect::<BTreeSet<_>>();

    if database_existence_map.values().any(|res| {

        matches!(

            res,

            Err(ListDatabasesError::ValidationError(

                ValidationError::AuthorizationError(_)

            ))

        )

    }) || user_existence_map.values().any(|res| {

        matches!(

            res,

            Err(ListUsersError::ValidationError(

                ValidationError::AuthorizationError(_)

            ))

        )

    }) {

        println!();

        print_authorization_owner_hint(&mut server_connection).await?;

        println!();

    }

    if diffs.is_empty() {

        println!("No changes to make.");

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

        return Ok(());

    }

    println!("The following changes will be made:\n");

    println!("{}", display_privilege_diffs(&diffs));

    if std::io::stdin().is_terminal()

        && !args.yes

        && !Confirm::new()

            .with_prompt("Do you want to apply these changes?")

            .default(false)

            .show_default(true)

            .interact()?

    {

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

        return Ok(());

    }

    let message = Request::ModifyPrivileges(diffs);

    server_connection.send(message).await?;

    let result = match server_connection.next().await {

        Some(Ok(Response::ModifyPrivileges(result))) => result,

        response => return erroneous_server_response(response),

    };

    print_modify_database_privileges_output_status(&result);

            Err(ModifyDatabasePrivilegesError::UserValidationError(

                ValidationError::AuthorizationError(_)

            ) | ModifyDatabasePrivilegesError::DatabaseValidationError(

                ValidationError::AuthorizationError(_)

            ))

        )

        print_authorization_owner_hint(&mut server_connection).await?;

    }

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

        std::process::exit(1);

    }

    Ok(())

}

                    "Failed parsing database privileges: `{priv_edit_entry}`"

                ))

    // TODO: handle errors better here

    }