floz_orm/

expr.rs

//! Expression tree for building WHERE clauses and filter conditions.
//!
//! Expressions are created via methods on `Column<T>` and composed
//! with `.and()`, `.or()`, `.not()`.
//!
//! ```ignore
//! use floz::prelude::*;
//!
//! let filter = col_age.gt(25).and(col_name.eq("Alice").or(col_name.eq("Bob")));
//! // Renders: (age > $1 AND (name = $2 OR name = $3))
//! ```

use std::fmt::Write;

use crate::column::AnyColumn;
use crate::value::Value;

/// A composable SQL expression node.
///
/// Built via `Column<T>` methods, composed via `.and()`, `.or()`, `.not()`.
/// Rendered to SQL + params via `to_sql()`.
#[derive(Debug, Clone)]
pub enum Expr {
    // ── Comparison ──
    /// `column = $N`
    Eq(AnyColumn, Value),
    /// `column != $N`
    Ne(AnyColumn, Value),
    /// `column > $N`
    Gt(AnyColumn, Value),
    /// `column >= $N`
    Gte(AnyColumn, Value),
    /// `column < $N`
    Lt(AnyColumn, Value),
    /// `column <= $N`
    Lte(AnyColumn, Value),

    // ── Range ──
    /// `column BETWEEN $N AND $M`
    Between(AnyColumn, Value, Value),
    /// `column IN ($N, $M, ...)` — empty list renders as `1=0`
    InList(AnyColumn, Vec<Value>),
    /// `column NOT IN ($N, $M, ...)` — empty list renders as `1=1`
    NotIn(AnyColumn, Vec<Value>),

    // ── String ──
    /// `column LIKE $N`
    Like(AnyColumn, Value),
    /// `column ILIKE $N` (case-insensitive, PostgreSQL)
    ILike(AnyColumn, Value),

    // ── Null ──
    /// `column IS NULL`
    IsNull(AnyColumn),
    /// `column IS NOT NULL`
    IsNotNull(AnyColumn),

    // ── Logical ──
    /// `(left AND right)`
    And(Box<Expr>, Box<Expr>),
    /// `(left OR right)`
    Or(Box<Expr>, Box<Expr>),
    /// `NOT (expr)`
    Not(Box<Expr>),
}

impl Expr {
    /// Combine with AND: `self AND other`
    pub fn and(self, other: Expr) -> Expr {
        Expr::And(Box::new(self), Box::new(other))
    }

    /// Combine with OR: `self OR other`
    pub fn or(self, other: Expr) -> Expr {
        Expr::Or(Box::new(self), Box::new(other))
    }

    /// Negate: `NOT self`
    pub fn not(self) -> Expr {
        Expr::Not(Box::new(self))
    }

    /// Render this expression to a SQL string fragment, pushing parameters into `params`
    /// and incrementing `idx` for each `$N` placeholder.
    ///
    /// The `idx` counter is shared across the entire query so parameter numbers
    /// are globally unique (e.g., a WHERE clause with 3 params followed by a
    /// HAVING clause continues from `$4`).
    pub fn to_sql(&self, sql: &mut String, params: &mut Vec<Value>, idx: &mut usize) {
        match self {
            // ── Comparison ──
            Expr::Eq(col, val) => {
                *idx += 1;
                write!(sql, "{} = ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }
            Expr::Ne(col, val) => {
                *idx += 1;
                write!(sql, "{} != ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }
            Expr::Gt(col, val) => {
                *idx += 1;
                write!(sql, "{} > ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }
            Expr::Gte(col, val) => {
                *idx += 1;
                write!(sql, "{} >= ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }
            Expr::Lt(col, val) => {
                *idx += 1;
                write!(sql, "{} < ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }
            Expr::Lte(col, val) => {
                *idx += 1;
                write!(sql, "{} <= ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }

            // ── Range ──
            Expr::Between(col, low, high) => {
                *idx += 1;
                let low_idx = *idx;
                *idx += 1;
                let high_idx = *idx;
                write!(sql, "{} BETWEEN ${} AND ${}", col.name(), low_idx, high_idx).unwrap();
                params.push(low.clone());
                params.push(high.clone());
            }
            Expr::InList(col, values) => {
                if values.is_empty() {
                    // Empty IN is logically impossible — short-circuit to FALSE
                    sql.push_str("1=0");
                } else {
                    write!(sql, "{} IN (", col.name()).unwrap();
                    for (i, val) in values.iter().enumerate() {
                        if i > 0 {
                            sql.push_str(", ");
                        }
                        *idx += 1;
                        write!(sql, "${}", idx).unwrap();
                        params.push(val.clone());
                    }
                    sql.push(')');
                }
            }
            Expr::NotIn(col, values) => {
                if values.is_empty() {
                    // Empty NOT IN excludes nothing — short-circuit to TRUE
                    sql.push_str("1=1");
                } else {
                    write!(sql, "{} NOT IN (", col.name()).unwrap();
                    for (i, val) in values.iter().enumerate() {
                        if i > 0 {
                            sql.push_str(", ");
                        }
                        *idx += 1;
                        write!(sql, "${}", idx).unwrap();
                        params.push(val.clone());
                    }
                    sql.push(')');
                }
            }

            // ── String ──
            Expr::Like(col, val) => {
                *idx += 1;
                write!(sql, "{} LIKE ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }
            Expr::ILike(col, val) => {
                *idx += 1;
                write!(sql, "{} ILIKE ${}", col.name(), idx).unwrap();
                params.push(val.clone());
            }

            // ── Null (no parameters) ──
            Expr::IsNull(col) => {
                write!(sql, "{} IS NULL", col.name()).unwrap();
            }
            Expr::IsNotNull(col) => {
                write!(sql, "{} IS NOT NULL", col.name()).unwrap();
            }

            // ── Logical (recursive with parentheses) ──
            Expr::And(left, right) => {
                sql.push('(');
                left.to_sql(sql, params, idx);
                sql.push_str(" AND ");
                right.to_sql(sql, params, idx);
                sql.push(')');
            }
            Expr::Or(left, right) => {
                sql.push('(');
                left.to_sql(sql, params, idx);
                sql.push_str(" OR ");
                right.to_sql(sql, params, idx);
                sql.push(')');
            }
            Expr::Not(inner) => {
                sql.push_str("NOT (");
                inner.to_sql(sql, params, idx);
                sql.push(')');
            }
        }
    }

    /// Convenience: render to a standalone (sql, params) tuple.
    /// Starts parameter numbering from $1.
    pub fn render(&self) -> (String, Vec<Value>) {
        let mut sql = String::new();
        let mut params = Vec::new();
        let mut idx = 0usize;
        self.to_sql(&mut sql, &mut params, &mut idx);
        (sql, params)
    }
}

/// An ordering expression for ORDER BY clauses.
#[derive(Debug, Clone)]
pub struct OrderExpr {
    pub(crate) column: AnyColumn,
    pub(crate) direction: OrderDirection,
}

/// The direction of an ORDER BY clause.
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum OrderDirection {
    Asc,
    Desc,
    AscNullsLast,
    DescNullsFirst,
}

impl OrderExpr {
    pub fn new(column: AnyColumn, direction: OrderDirection) -> Self {
        Self { column, direction }
    }

    /// Render this ordering clause to SQL.
    pub fn to_sql(&self, sql: &mut String) {
        sql.push_str(self.column.name());
        match self.direction {
            OrderDirection::Asc => sql.push_str(" ASC"),
            OrderDirection::Desc => sql.push_str(" DESC"),
            OrderDirection::AscNullsLast => sql.push_str(" ASC NULLS LAST"),
            OrderDirection::DescNullsFirst => sql.push_str(" DESC NULLS FIRST"),
        }
    }

    /// Convenience: render to a standalone SQL string.
    pub fn render(&self) -> String {
        let mut sql = String::new();
        self.to_sql(&mut sql);
        sql
    }
}

// ═══════════════════════════════════════════════════════════════
// Tests
// ═══════════════════════════════════════════════════════════════

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

    fn col_id() -> Column<i32> { Column::new("id", "users") }
    fn col_age() -> Column<i32> { Column::new("age", "users") }
    fn col_name() -> Column<String> { Column::new("name", "users") }
    fn col_email() -> Column<String> { Column::new("email", "users") }

    // ── Comparison rendering ──

    #[test]
    fn render_eq() {
        let (sql, params) = col_age().eq(25).render();
        assert_eq!(sql, "age = $1");
        assert_eq!(params, vec![Value::Int(25)]);
    }

    #[test]
    fn render_ne() {
        let (sql, params) = col_age().ne(0).render();
        assert_eq!(sql, "age != $1");
        assert_eq!(params, vec![Value::Int(0)]);
    }

    #[test]
    fn render_gt() {
        let (sql, params) = col_age().gt(25).render();
        assert_eq!(sql, "age > $1");
        assert_eq!(params, vec![Value::Int(25)]);
    }

    #[test]
    fn render_gte() {
        let (sql, params) = col_age().gte(18).render();
        assert_eq!(sql, "age >= $1");
        assert_eq!(params, vec![Value::Int(18)]);
    }

    #[test]
    fn render_lt() {
        let (sql, params) = col_age().lt(65).render();
        assert_eq!(sql, "age < $1");
        assert_eq!(params, vec![Value::Int(65)]);
    }

    #[test]
    fn render_lte() {
        let (sql, params) = col_age().lte(100).render();
        assert_eq!(sql, "age <= $1");
        assert_eq!(params, vec![Value::Int(100)]);
    }

    // ── Range rendering ──

    #[test]
    fn render_between() {
        let (sql, params) = col_age().between(18, 65).render();
        assert_eq!(sql, "age BETWEEN $1 AND $2");
        assert_eq!(params, vec![Value::Int(18), Value::Int(65)]);
    }

    #[test]
    fn render_in_list() {
        let (sql, params) = col_id().in_list(vec![1, 2, 3]).render();
        assert_eq!(sql, "id IN ($1, $2, $3)");
        assert_eq!(params, vec![Value::Int(1), Value::Int(2), Value::Int(3)]);
    }

    #[test]
    fn render_in_list_single() {
        let (sql, params) = col_id().in_list(vec![42]).render();
        assert_eq!(sql, "id IN ($1)");
        assert_eq!(params, vec![Value::Int(42)]);
    }

    #[test]
    fn render_in_list_empty() {
        let (sql, params) = col_id().in_list(Vec::<i32>::new()).render();
        assert_eq!(sql, "1=0");
        assert!(params.is_empty());
    }

    #[test]
    fn render_not_in() {
        let (sql, params) = col_id().not_in(vec![4, 5]).render();
        assert_eq!(sql, "id NOT IN ($1, $2)");
        assert_eq!(params, vec![Value::Int(4), Value::Int(5)]);
    }

    #[test]
    fn render_not_in_empty() {
        let (sql, params) = col_id().not_in(Vec::<i32>::new()).render();
        assert_eq!(sql, "1=1");
        assert!(params.is_empty());
    }

    // ── String rendering ──

    #[test]
    fn render_like() {
        let (sql, params) = col_name().like("A%").render();
        assert_eq!(sql, "name LIKE $1");
        assert_eq!(params, vec![Value::String("A%".into())]);
    }

    #[test]
    fn render_ilike() {
        let (sql, params) = col_name().ilike("alice%").render();
        assert_eq!(sql, "name ILIKE $1");
        assert_eq!(params, vec![Value::String("alice%".into())]);
    }

    #[test]
    fn render_contains() {
        let (sql, params) = col_name().contains("foo").render();
        assert_eq!(sql, "name LIKE $1");
        assert_eq!(params, vec![Value::String("%foo%".into())]);
    }

    #[test]
    fn render_starts_with() {
        let (sql, params) = col_name().starts_with("A").render();
        assert_eq!(sql, "name LIKE $1");
        assert_eq!(params, vec![Value::String("A%".into())]);
    }

    #[test]
    fn render_ends_with() {
        let (sql, params) = col_name().ends_with("z").render();
        assert_eq!(sql, "name LIKE $1");
        assert_eq!(params, vec![Value::String("%z".into())]);
    }

    // ── Null rendering ──

    #[test]
    fn render_is_null() {
        let (sql, params) = col_email().is_null().render();
        assert_eq!(sql, "email IS NULL");
        assert!(params.is_empty());
    }

    #[test]
    fn render_is_not_null() {
        let (sql, params) = col_email().is_not_null().render();
        assert_eq!(sql, "email IS NOT NULL");
        assert!(params.is_empty());
    }

    // ── Logical rendering ──

    #[test]
    fn render_and() {
        let (sql, params) = col_age().gt(25).and(col_name().eq("Alice")).render();
        assert_eq!(sql, "(age > $1 AND name = $2)");
        assert_eq!(params, vec![Value::Int(25), Value::String("Alice".into())]);
    }

    #[test]
    fn render_or() {
        let (sql, params) = col_age().lt(18).or(col_age().gt(65)).render();
        assert_eq!(sql, "(age < $1 OR age > $2)");
        assert_eq!(params, vec![Value::Int(18), Value::Int(65)]);
    }

    #[test]
    fn render_not() {
        let (sql, params) = col_email().is_null().not().render();
        assert_eq!(sql, "NOT (email IS NULL)");
        assert!(params.is_empty());
    }

    #[test]
    fn render_nested_and_or() {
        // age > 25 AND (name = 'Alice' OR name = 'Bob')
        let expr = col_age().gt(25).and(
            col_name().eq("Alice").or(col_name().eq("Bob")),
        );
        let (sql, params) = expr.render();
        assert_eq!(sql, "(age > $1 AND (name = $2 OR name = $3))");
        assert_eq!(params, vec![
            Value::Int(25),
            Value::String("Alice".into()),
            Value::String("Bob".into()),
        ]);
    }

    #[test]
    fn render_deep_nesting() {
        // NOT (age < 18 OR age > 65)
        let expr = col_age().lt(18).or(col_age().gt(65)).not();
        let (sql, params) = expr.render();
        assert_eq!(sql, "NOT ((age < $1 OR age > $2))");
        assert_eq!(params, vec![Value::Int(18), Value::Int(65)]);
    }

    #[test]
    fn render_complex_filter() {
        // (age BETWEEN 18 AND 65) AND (email IS NOT NULL) OR (name = 'admin')
        let expr = col_age()
            .between(18, 65)
            .and(col_email().is_not_null())
            .or(col_name().eq("admin"));
        let (sql, params) = expr.render();
        assert_eq!(
            sql,
            "((age BETWEEN $1 AND $2 AND email IS NOT NULL) OR name = $3)"
        );
        assert_eq!(params, vec![
            Value::Int(18),
            Value::Int(65),
            Value::String("admin".into()),
        ]);
    }

    // ── Parameter counter continuity ──

    #[test]
    fn render_shared_counter() {
        // Simulate two expressions sharing a counter (as in WHERE + HAVING)
        let mut sql = String::new();
        let mut params = Vec::new();
        let mut idx = 0usize;

        // First expression: age > $1
        col_age().gt(25).to_sql(&mut sql, &mut params, &mut idx);
        sql.push_str(" AND ");
        // Second expression: name = $2 (continues from $1)
        col_name().eq("Alice").to_sql(&mut sql, &mut params, &mut idx);

        assert_eq!(sql, "age > $1 AND name = $2");
        assert_eq!(idx, 2);
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn render_many_params() {
        // 5 IN list values → $1..$5, then one more → $6
        let mut sql = String::new();
        let mut params = Vec::new();
        let mut idx = 0usize;

        col_id().in_list(vec![1, 2, 3, 4, 5]).to_sql(&mut sql, &mut params, &mut idx);
        sql.push_str(" AND ");
        col_name().eq("test").to_sql(&mut sql, &mut params, &mut idx);

        assert_eq!(sql, "id IN ($1, $2, $3, $4, $5) AND name = $6");
        assert_eq!(params.len(), 6);
        assert_eq!(idx, 6);
    }

    // ── ORDER BY rendering ──

    #[test]
    fn render_order_asc() {
        assert_eq!(col_name().asc().render(), "name ASC");
    }

    #[test]
    fn render_order_desc() {
        assert_eq!(col_age().desc().render(), "age DESC");
    }

    #[test]
    fn render_order_asc_nulls_last() {
        assert_eq!(col_age().asc_nulls_last().render(), "age ASC NULLS LAST");
    }

    #[test]
    fn render_order_desc_nulls_first() {
        assert_eq!(col_age().desc_nulls_first().render(), "age DESC NULLS FIRST");
    }

    // ── Edge cases ──

    #[test]
    fn render_is_null_no_params() {
        let (_, params) = col_email().is_null().render();
        assert!(params.is_empty(), "IS NULL should not produce parameters");
    }

    #[test]
    fn render_and_with_null() {
        // age > 25 AND email IS NULL
        let (sql, params) = col_age().gt(25).and(col_email().is_null()).render();
        assert_eq!(sql, "(age > $1 AND email IS NULL)");
        assert_eq!(params.len(), 1); // only one param from gt
    }
}