db_builder/src/schemas/builders.rs

use crate::mappings::SQLiteDatatypes;
use crate::schemas::entities::{Column, Table};

pub struct ColumnBuilder {
    name: String,
    datatype: SQLiteDatatypes,
    nullable: bool,
    default: Option<String>,
    auto_increment: bool,
    unique: bool,
    check_constraint: Option<String>,
    primary_key: bool,
}

impl ColumnBuilder {
    pub fn new() -> ColumnBuilder {
        ColumnBuilder {
            name: String::new(),
            datatype: SQLiteDatatypes::Text,
            nullable: false,
            default: None,
            auto_increment: false,
            unique: false,
            check_constraint: None,
            primary_key: false,
        }
    }

    pub fn with_name(mut self, name: String) -> Self {
        self.name = name;
        self
    }

    pub fn with_datatype(mut self, datatype: SQLiteDatatypes) -> Self {
        self.datatype = datatype;
        self
    }

    pub fn with_nullable(mut self) -> Self {
        self.nullable = true;
        self
    }

    pub fn with_default(mut self, default: String) -> Self {
        self.default = Some(default);
        self
    }

    pub fn with_auto_increment(mut self) -> Self {
        self.auto_increment = true;
        self
    }

    pub fn with_unique(mut self) -> Self {
        self.unique = true;
        self
    }

    pub fn with_check_constraint(mut self, constraint: String) -> Self {
        self.check_constraint = Some(constraint);
        self
    }
    
    pub fn with_primary_key(mut self) -> Self {
        self.primary_key = true;
        self
    }

    pub fn build(self) -> Result<Column, String> {
        if self.auto_increment && self.datatype != SQLiteDatatypes::Integer {
            return Err("Cannot set AUTO_INCREMENT on non-INTEGER column".to_string());
        }

        Ok(Column {
            name: self.name,
            datatype: self.datatype,
            nullable: self.nullable,
            default: self.default,
            auto_increment: self.auto_increment,
            unique: self.unique,
            check_constraint: self.check_constraint,
            primary_key: self.primary_key,
        })
    }
}

impl Default for ColumnBuilder {
    fn default() -> Self {
        Self::new()
    }
}

pub struct TableBuilder {
    name: String,
    columns: Vec<Column>,
    strict: bool
}

impl TableBuilder {
    pub fn new() -> TableBuilder {
        TableBuilder {
            name: String::new(),
            columns: Vec::new(),
            strict: false,
        }
    }

    pub fn with_name(mut self, name: String) -> Self {
        self.name = name;
        self
    }

    pub fn with_strict(mut self) -> Self {
        self.strict = true;
        self
    }

    pub fn with_column(mut self, column: Column) -> Self {
        self.columns.push(column);
        self
    }

    pub fn build(self) -> Table {
        Table { name: self.name, columns: self.columns, strict: self.strict }
    }
}

impl Default for TableBuilder {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod test {
    use crate::mappings::SQLiteDatatypes;
    use crate::schemas::builders::{ColumnBuilder, TableBuilder};

    #[test]
    fn test_column_builder() {
        let result = ColumnBuilder::new()
            .with_name("name".to_string())
            .with_datatype(SQLiteDatatypes::Text)
            .with_nullable()
            .build();

        match result {
            Ok(column) => {
                assert_eq!(column.name, String::from("name"));
                assert_eq!(column.datatype, SQLiteDatatypes::Text);
                assert_eq!(column.nullable, true);
            },
            Err(_) => {
                assert!(false, "should not fail");
            }
        }
    }

    #[test]
    fn test_column_builder_should_fail() {
        let result = ColumnBuilder::new()
            .with_name("name".to_string())
            .with_datatype(SQLiteDatatypes::Blob)
            .with_auto_increment()
            .build();

        match result {
            Ok(_) => {
                assert!(false, "Should not make auto increment with another type than integer")
            },
            Err(_) => {
                assert!(true);
            }
        }
    }

    #[test]
    fn test_table_builder() {
        let column = ColumnBuilder::new()
            .with_name("id".to_string())
            .with_datatype(SQLiteDatatypes::Integer)
            .with_auto_increment()
            .build()
            .expect("Failed to create id column");

        let table = TableBuilder::new()
            .with_name("my_table".to_string())
            .with_column(column.clone())
            .build();

        assert_eq!(table.name, String::from("my_table"));
        assert_eq!(*table.columns.first().unwrap(), column);
    }
}