sqlite-clone/sqlite_core/src/statement.rs

use crate::row;
use crate::row::Serialize;
use crate::table::Table;

pub enum StatementType {
    Insert { row: row::Row },
    Select,
}

pub enum StatementResultType {
    Insert,
    Select { rows: Vec<row::Row> },
}

pub enum ExecuteResult {
    Error {
        error: String,
    },
    Success {
        statement_result_type: StatementResultType,
    },
}

pub struct Statement {
    statement_type: StatementType,
}

impl Statement {
    pub fn new(statement_type: StatementType) -> Self {
        Self { statement_type }
    }

    pub fn parse_statement(command: &String) -> Result<Self, String> {
        if command.starts_with("insert") {
            match sscanf::scanf!(command, "insert {} {} {}", usize, str, str) {
                Ok((id, username, email)) => {
                    match row::Row::new(
                        u32::try_from(id).unwrap(),
                        username.to_string(),
                        email.to_string(),
                    ) {
                        Ok(row) => Ok(Statement::new(StatementType::Insert { row })),
                        Err(e) => Err(e),
                    }
                }
                _ => Err(String::from("could not parse insert statement")),
            }
        } else if command.starts_with("select") {
            Ok(Statement::new(StatementType::Select))
        } else {
            Err(String::from("Could not parse command"))
        }
    }

    pub fn execute(&self, table: &mut Table) -> ExecuteResult {
        match &self.statement_type {
            StatementType::Insert { row } => match row.serialize() {
                Err(e) => ExecuteResult::Error {
                    error: e.to_string(),
                },
                Ok(serialization) => {
                    table.append_row(serialization);
                    ExecuteResult::Success {
                        statement_result_type: StatementResultType::Insert {},
                    }
                }
            },
            StatementType::Select => {
                let rows = table.get_rows();

                return ExecuteResult::Success {
                    statement_result_type: StatementResultType::Select { rows },
                };
            }
        }
    }
}