use crate::prelude::*;

#[derive(Debug)]
pub enum Expression {
    Column { table: Table, column: Column },
    Value(Value),
    Param(Param),
    Unknown,
}

impl Sql for Expression {
    fn sql(&self, s: String, ctx: &Context) -> Result<String> {
        match self {
            Expression::Column { table, column } => {
                let mut s = table.sql(s, ctx)?;
                s.push('.');
                let s = column.sql(s, ctx);

                s
            }
            Expression::Value(value) => {
                let s = value.sql(s, ctx);

                s
            }
            Expression::Param(param) => {
                let s = param.sql(s, ctx);

                s
            }
            Expression::Unknown => Err(SqlGenError::ParseFailed(
                "Was not able to parse Expression".into(),
            )),
        }
    }
}

impl From<&str> for Expression {
    fn from(value: &str) -> Self {
        match value {
            param if param.starts_with(':') => Expression::Param(Param::Param(param.into())),
            column if column.contains('.') => {
                let split: Vec<&str> = column.split('.').collect();
                match split[..] {
                    [table, column] => Expression::Column {
                        table: table.into(),
                        column: column.into(),
                    },
                    _ => Expression::Unknown,
                }
            }
            value => Expression::Value(value.into()),
        }
    }
}