pub enum Statement {
    Insert,
    Select,
}

pub enum StatementParseError {
    Unrecognized { stmt: String },
}

impl std::fmt::Display for StatementParseError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            StatementParseError::Unrecognized { stmt } => {
                write!(f, "unrecognized statement {stmt:?}")
            }
        }
    }
}

impl std::str::FromStr for Statement {
    type Err = StatementParseError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let s = s.trim();
        let lower = s.to_lowercase();
        if lower.starts_with("insert") {
            Ok(Statement::Insert)
        } else if lower.starts_with("select") {
            Ok(Statement::Select)
        } else {
            Err(StatementParseError::Unrecognized {
                stmt: s.to_string(),
            })
        }
    }
}

pub struct StatementExecuteResult {}

impl Statement {
    pub fn execute(&self) -> StatementExecuteResult {
        match self {
            Statement::Insert => println!("insert"),
            Statement::Select => println!("select"),
        }
        StatementExecuteResult {}
    }
}