serde_rusqlite 0.43.0

use std::marker::PhantomData;

use rusqlite::{Row, Rows};
use serde_core::de::DeserializeOwned;

use crate::{Error, Result};

/// Iterator to automatically deserialize each row from owned `rusqlite::Rows` into `D: serde::Deserialize`
pub struct DeserRows<'stmt, D> {
	rows: Rows<'stmt>,
	columns: Option<Vec<String>>,
	d: PhantomData<*const D>,
}

impl<'stmt, D: DeserializeOwned> DeserRows<'stmt, D> {
	pub fn new(rows: Rows<'stmt>) -> Self {
		Self {
			columns: columns_from_rows(&rows),
			rows,
			d: PhantomData,
		}
	}
}

impl<D: DeserializeOwned> Iterator for DeserRows<'_, D> {
	type Item = Result<D>;

	fn next(&mut self) -> Option<Self::Item> {
		deser_row(self.rows.next(), &self.columns)
	}
}

/// Iterator to automatically deserialize each row from borrowed `rusqlite::Rows` into `D: serde::Deserialize`
pub struct DeserRowsRef<'rows, 'stmt, D> {
	rows: &'rows mut Rows<'stmt>,
	columns: Option<Vec<String>>,
	d: PhantomData<*const D>,
}

impl<'rows, 'stmt, D: DeserializeOwned> DeserRowsRef<'rows, 'stmt, D> {
	pub fn new(rows: &'rows mut Rows<'stmt>) -> Self {
		Self {
			columns: columns_from_rows(rows),
			rows,
			d: PhantomData,
		}
	}
}

impl<D: DeserializeOwned> Iterator for DeserRowsRef<'_, '_, D> {
	type Item = Result<D>;

	fn next(&mut self) -> Option<Self::Item> {
		deser_row(self.rows.next(), &self.columns)
	}
}

#[inline]
fn deser_row<D: DeserializeOwned>(row: rusqlite::Result<Option<&Row>>, columns: &Option<Vec<String>>) -> Option<Result<D>> {
	if let Some(columns) = columns {
		match row {
			Ok(Some(row)) => Some(crate::from_row_with_columns(row, columns)),
			Ok(None) => None,
			Err(e) => Some(Err(e.into())),
		}
	} else {
		Some(Err(Error::ColumnNamesNotAvailable))
	}
}

fn columns_from_rows(rows: &Rows) -> Option<Vec<String>> {
	rows.as_ref().map(|stmt| {
		let len = stmt.column_count();
		let mut out = Vec::with_capacity(len);
		for i in 0..len {
			out.push(stmt.column_name(i).expect("Impossible, we checked the length").to_owned())
		}
		out
	})
}