osdb/src/command.rs

use crate::meta_commands::{MetaCommand, MetaCommandExecuteResult, MetaCommandParseError};
use crate::statements::{Statement, StatementExecuteResult, StatementParseError};

#[derive(Debug)]
pub enum Command {
    MetaCommand(MetaCommand),
    Statement(Statement),
}

#[derive(Debug)]
pub struct CommandExecuteResult {
    pub should_exit: bool,
    msg: String,
}

impl CommandExecuteResult {
    pub fn display(&self) -> String {
        self.msg.to_string()
    }
}

impl From<MetaCommandExecuteResult> for CommandExecuteResult {
    fn from(value: MetaCommandExecuteResult) -> Self {
        Self {
            should_exit: value.should_exit,
            msg: String::new(),
        }
    }
}

impl From<StatementExecuteResult> for CommandExecuteResult {
    fn from(value: StatementExecuteResult) -> Self {
        Self {
            should_exit: false,
            msg: value.msg,
        }
    }
}

impl Command {
    pub fn execute(&self) -> CommandExecuteResult {
        match self {
            Command::MetaCommand(cmd) => cmd.execute().into(),
            Command::Statement(stmt) => stmt.execute().into(),
        }
    }
}

#[derive(Debug)]
pub enum CommandParseError {
    MetaCommand(MetaCommandParseError),
    Statement(StatementParseError),
}

impl std::fmt::Display for CommandParseError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            CommandParseError::MetaCommand(meta_command_parse_error) => {
                write!(f, "{meta_command_parse_error}")
            }
            CommandParseError::Statement(statement_parse_error) => {
                write!(f, "{statement_parse_error}")
            }
        }
    }
}

impl From<MetaCommand> for Command {
    fn from(value: MetaCommand) -> Self {
        Command::MetaCommand(value)
    }
}

impl From<MetaCommandParseError> for CommandParseError {
    fn from(value: MetaCommandParseError) -> Self {
        CommandParseError::MetaCommand(value)
    }
}

impl From<Statement> for Command {
    fn from(value: Statement) -> Self {
        Command::Statement(value)
    }
}

impl From<StatementParseError> for CommandParseError {
    fn from(value: StatementParseError) -> Self {
        CommandParseError::Statement(value)
    }
}

impl std::str::FromStr for Command {
    type Err = CommandParseError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if s.starts_with(".") {
            s.parse::<MetaCommand>()
                .map(|x| x.into())
                .map_err(|x| x.into())
        } else {
            s.parse::<Statement>()
                .map(|x| x.into())
                .map_err(|x| x.into())
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::{command::Command, meta_commands::MetaCommand, statements::Statement};
    use insta::{assert_debug_snapshot, assert_snapshot};

    #[test]
    fn test_execute_insert_statement() {
        let statement: Command = Statement::Insert.into();
        let result = statement.execute().display();
        assert_snapshot!(result);
    }

    #[test]
    fn test_execute_select_statement() {
        let statement: Command = Statement::Select.into();
        let result = statement.execute().display();
        assert_snapshot!(result);
    }

    #[test]
    fn test_execute_exit_metacommand() {
        assert_debug_snapshot!(Into::<Command>::into(MetaCommand::Exit).execute());
    }

    #[test]
    fn test_parse_wrong_statement() {
        assert_debug_snapshot!("salact".parse::<Command>());
    }
}