const tokens = @import("tokens.zig");
const Token = tokens.Token;

pub const ExprType = enum {
    Unary,
    Binary,
    Grouping,
    Number,
    Bool,
    Nil,
    String,
};

pub const Expr = union(ExprType) {
    Unary: UnaryExpr,
    Binary: BinaryExpr,
    Grouping: Grouping,
    Number: Number,
    Bool: Bool,
    Nil: Nil,
    String: String,
};

pub const UnaryExpr = struct {
    operator: Token,
    right: *Expr,
};

pub fn mkUnary(operator: Token, right: *Expr) Expr {
    return Expr{
        .Unary = UnaryExpr{
            .operator = operator,
            .right = right,
        },
    };
}

pub const BinaryExpr = struct {
    left: *Expr,
    operator: Token,
    right: *Expr,
};

pub fn mkBinary(left: *Expr, operator: Token, right: *Expr) Expr {
    return Expr{
        .Binary = BinaryExpr{
            .left = left,
            .operator = operator,
            .right = right,
        },
    };
}

pub const Grouping = struct {
    expression: *Expr,
};

pub fn mkGrouping(expression: *Expr) Expr {
    return Expr{
        .Grouping = Grouping{
            .expression = expression,
        },
    };
}

/// Represents the default number literals in V.
pub const NumberType = enum {
    Integer32,
    Integer64,
    Unsigned32,
    Unsigned64,
    Float32,
    Float64,
};

/// "translation" of V number types to Zig number types for nicer
/// representation.
pub const Number = union(NumberType) {
    Integer32: i32,
    Integer64: i64,
    Unsigned32: u32,
    Unsigned64: u64,
    Float32: f32,
    Float64: f64,
};

pub fn mkNum(comptime T: type, num: T) Expr {
    var expr = switch (T) {
        i32 => Expr{ .Number = Number{ .Integer32 = num } },
        i64 => Expr{ .Number = Number{ .Integer64 = num } },
        u32 => Expr{ .Number = Number{ .Unsigned32 = num } },
        u64 => Expr{ .Number = Number{ .Unsigned64 = num } },
        f32 => Expr{ .Number = Number{ .Float32 = num } },
        f64 => Expr{ .Number = Number{ .Float64 = num } },
        else => unreachable,
    };

    return expr;
}

pub const Bool = bool;
pub const Nil = void;
pub const String = []u8;