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/*!
Collection of types and helpers for building hopefully correctly escaped SQL queries.

Example usage
=============

```rust
use format_sql_query::*;

println!("SELECT {} FROM {} WHERE {} = {}", Column("foo bar".into()), Table::with_schema("foo", "baz"), Column("blah".into()), QuotedData("hello 'world' foo"));
// SELECT "foo bar" FROM foo.baz WHERE blah = 'hello ''world'' foo'
```
 */
use std::fmt;
use itertools::Itertools;

/// Object like table, schema, column etc.
///
/// Escaping rules:
/// * as is if does not contain " or space
/// * put in " and escape " with ""
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Object<'i>(pub &'i str);

impl<'i> From<&'i str> for Object<'i> {
    fn from(value: &'i str) -> Object<'i> {
        Object(value)
    }
}

impl fmt::Display for Object<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if self.0.contains("'") || self.0.contains("\\") {
            // MonetDB does not like ' or \ in column names
            return Err(fmt::Error)
        }

        if self.0.contains(" ") || self.0.contains("\"") {
            f.write_str("\"")?;
            for part in self.0.split("\"").intersperse("\"\"") {
                f.write_str(part)?;
            }
            f.write_str("\"")?;
        } else {
            f.write_str(self.0)?;
        }
        Ok(())
    }
}

/// Strings and other data in single quotes.
///
/// Escaping rules:
/// * put in ' and escape ' with ''
/// * escape / with //
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct QuotedData<'i>(pub &'i str);

impl<'i> From<&'i str> for QuotedData<'i> {
    fn from(value: &'i str) -> QuotedData<'i> {
        QuotedData(value)
    }
}

impl<'i> QuotedData<'i> {
    pub fn map<F>(self, f: F) -> MapQuotedData<'i, F> where F: Fn(&'i str) -> String {
        MapQuotedData(self.0, f)
    }
}

impl fmt::Display for QuotedData<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.write_str("'")?;
        for part in self.0.split("'").intersperse("''") {
            for part in part.split("\\").intersperse("\\\\") {
                f.write_str(part)?;
            }
        }
        f.write_str("'")?;
        Ok(())
    }
}

/// Wrapper around `QuotedData` that maps its content.
pub struct MapQuotedData<'i, F>(pub &'i str, F);

impl<'i, F> fmt::Display for MapQuotedData<'i, F> where F: Fn(&'i str) -> String {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let data = self.1(self.0);
        write!(f, "{}", QuotedData(&data))
    }
}

/// Represents table name with optional schema.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Table<'i> {
    pub schema: Option<Object<'i>>,
    pub table: Object<'i>,
}

impl<'i> Table<'i> {
    pub fn with_schema(schema: impl Into<Object<'i>>, table: impl Into<Object<'i>>) -> Table<'i> {
        Table {
            schema: Some(schema.into()),
            table: table.into(),
        }
    }

    pub fn new(table: impl Into<Object<'i>>) -> Table<'i> {
        Table {
            schema: None,
            table: table.into(),
        }
    }
}

impl fmt::Display for Table<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        if let Some(schema) = self.schema {
            write!(f, "{}", Object(&format!("{}.{}", schema.0, self.table.0)))
        } else {
            write!(f, "{}", self.table)
        }
    }
}

/// Represents table column name.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Column<'i>(pub Object<'i>);

impl<'i> From<&'i str> for Column<'i> {
    fn from(value: &'i str) -> Column<'i> {
        Column(value.into())
    }
}

impl fmt::Display for Column<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl<'i> Column<'i> {
    pub fn new(name: impl Into<Object<'i>>) -> Column<'i> {
        Column(name.into())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_works() {
        assert_eq!(
            r#"SELECT "foo bar" FROM foo.baz WHERE blah = 'hello ''world'' foo'"#,
            &format!("SELECT {} FROM {} WHERE {} = {}", Column("foo bar".into()), Table::with_schema("foo", "baz"), Column("blah".into()), QuotedData("hello 'world' foo"))
        )
    }
}