use crate::ast::environment::Environment;
use crate::ast::types::{Signature, StaticType, Value};
use std::rc::Rc;

pub fn register(env: &Environment) {
    register_constants(env);
    register_arithmetic(env);
    register_comparison(env);
    register_logic(env);
}

fn register_constants(env: &Environment) {
    // True/False are keywords or literals in parser, but could be exposed as constants too if needed.
    // In Delphi RTL: CFalse, CTrue, CNaN

    // We register NaN as a value, not a function.
    env.register_constant("NaN", StaticType::Float, Value::Float(f64::NAN));
    env.register_constant("true", StaticType::Bool, Value::Bool(true));
    env.register_constant("false", StaticType::Bool, Value::Bool(false));
}

fn register_arithmetic(env: &Environment) {
    // --- Add (+) ---
    let add_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
            ret: StaticType::Int,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Float, StaticType::Float]),
            ret: StaticType::Float,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Text, StaticType::Text]),
            ret: StaticType::Text,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::DateTime, StaticType::Int]),
            ret: StaticType::DateTime,
        },
    ]);
    env.register_native("+", add_ty, true, |args| {
        if args.len() == 2 {
            match (&args[0], &args[1]) {
                (Value::Int(a), Value::Int(b)) => Value::Int(a + b),
                (Value::Float(a), Value::Float(b)) => Value::Float(a + b),
                (Value::Int(a), Value::Float(b)) => Value::Float(*a as f64 + b),
                (Value::Float(a), Value::Int(b)) => Value::Float(a + *b as f64),
                (Value::Text(a), Value::Text(b)) => {
                    let mut res = a.to_string();
                    res.push_str(b);
                    Value::Text(Rc::from(res))
                }
                (Value::DateTime(ts), Value::Int(ms)) => Value::DateTime(ts + ms),
                _ => Value::Void,
            }
        } else {
            // Variadic sum
            let mut acc = 0.0;
            for arg in args {
                if let Value::Int(i) = arg {
                    acc += i as f64;
                } else if let Value::Float(f) = arg {
                    acc += f;
                }
            }
            if acc.fract() == 0.0 {
                Value::Int(acc as i64)
            } else {
                Value::Float(acc)
            }
        }
    });

    // --- Subtract (-) ---
    let sub_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
            ret: StaticType::Int,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Float, StaticType::Float]),
            ret: StaticType::Float,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int]),
            ret: StaticType::Int,
        }, // Negation
        Signature {
            params: StaticType::Tuple(vec![StaticType::Float]),
            ret: StaticType::Float,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::DateTime, StaticType::DateTime]),
            ret: StaticType::Int,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::DateTime, StaticType::Int]),
            ret: StaticType::DateTime,
        },
    ]);
    env.register_native("-", sub_ty, true, |args| {
        if args.is_empty() {
            return Value::Void;
        }
        if args.len() == 1 {
            return match args[0] {
                Value::Int(i) => Value::Int(-i),
                Value::Float(f) => Value::Float(-f),
                _ => Value::Void,
            };
        }
        if args.len() == 2 {
            return match (&args[0], &args[1]) {
                (Value::Int(a), Value::Int(b)) => Value::Int(a - b),
                (Value::Float(a), Value::Float(b)) => Value::Float(a - b),
                (Value::Int(a), Value::Float(b)) => Value::Float(*a as f64 - b),
                (Value::Float(a), Value::Int(b)) => Value::Float(a - *b as f64),
                (Value::DateTime(a), Value::DateTime(b)) => Value::Int(a - b),
                (Value::DateTime(a), Value::Int(b)) => Value::DateTime(a - b),
                _ => Value::Void,
            };
        }
        // Variadic sub
        let mut acc = match args[0] {
            Value::Int(i) => i as f64,
            Value::Float(f) => f,
            _ => return Value::Void,
        };
        for arg in &args[1..] {
            if let Value::Int(i) = arg {
                acc -= *i as f64;
            } else if let Value::Float(f) = arg {
                acc -= f;
            }
        }
        if acc.fract() == 0.0 {
            Value::Int(acc as i64)
        } else {
            Value::Float(acc)
        }
    });

    // --- Multiply (*) ---
    let mul_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
            ret: StaticType::Int,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Float, StaticType::Float]),
            ret: StaticType::Float,
        },
    ]);
    env.register_native("*", mul_ty, true, |args| {
        if args.len() == 2 {
            match (&args[0], &args[1]) {
                (Value::Int(a), Value::Int(b)) => Value::Int(a * b),
                (Value::Float(a), Value::Float(b)) => Value::Float(a * b),
                (Value::Int(a), Value::Float(b)) => Value::Float(*a as f64 * b),
                (Value::Float(a), Value::Int(b)) => Value::Float(a * *b as f64),
                _ => Value::Void,
            }
        } else {
            let mut acc = 1.0;
            for arg in args {
                if let Value::Int(i) = arg {
                    acc *= i as f64;
                } else if let Value::Float(f) = arg {
                    acc *= f;
                }
            }
            if acc.fract() == 0.0 {
                Value::Int(acc as i64)
            } else {
                Value::Float(acc)
            }
        }
    });

    // --- Divide (/) ---
    let div_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
            ret: StaticType::Float,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Float, StaticType::Float]),
            ret: StaticType::Float,
        },
    ]);
    env.register_native("/", div_ty, true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        let a = match args[0] {
            Value::Int(i) => i as f64,
            Value::Float(f) => f,
            _ => return Value::Void,
        };
        let b = match args[1] {
            Value::Int(i) => i as f64,
            Value::Float(f) => f,
            _ => return Value::Void,
        };
        if b == 0.0 {
            Value::Float(f64::NAN)
        } else {
            Value::Float(a / b)
        }
    });

    // --- Integer Divide (//) ---
    let int_div_ty = StaticType::Function(Box::new(Signature {
        params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
        ret: StaticType::Int,
    }));
    env.register_native("//", int_div_ty, true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => {
                if *b == 0 {
                    Value::Void
                } else {
                    Value::Int(a / b)
                }
            }
            // Also allow float truncation? Delphi RTL says IntDivide takes DataValue and returns DataValue.
            // Usually div is for integers. Let's stick to Int.
            _ => Value::Void,
        }
    });

    // --- Modulus (%) ---
    let mod_ty = StaticType::Function(Box::new(Signature {
        params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
        ret: StaticType::Int,
    }));
    env.register_native("%", mod_ty, true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => {
                if *b == 0 {
                    Value::Void
                } else {
                    Value::Int(a % b)
                }
            }
            _ => Value::Void,
        }
    });
}

fn register_comparison(env: &Environment) {
    let cmp_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
            ret: StaticType::Bool,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Float, StaticType::Float]),
            ret: StaticType::Bool,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::DateTime, StaticType::DateTime]),
            ret: StaticType::Bool,
        },
    ]);

    // --- Greater Than (>) ---
    env.register_native(">", cmp_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Bool(a > b),
            (Value::Int(a), Value::Float(b)) => Value::Bool((*a as f64) > *b),
            (Value::Float(a), Value::Int(b)) => Value::Bool(*a > (*b as f64)),
            (Value::Float(a), Value::Float(b)) => Value::Bool(a > b),
            (Value::DateTime(a), Value::DateTime(b)) => Value::Bool(a > b),
            _ => Value::Bool(false),
        }
    });

    // --- Less Than (<) ---
    env.register_native("<", cmp_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Bool(a < b),
            (Value::Int(a), Value::Float(b)) => Value::Bool((*a as f64) < *b),
            (Value::Float(a), Value::Int(b)) => Value::Bool(*a < (*b as f64)),
            (Value::Float(a), Value::Float(b)) => Value::Bool(a < b),
            (Value::DateTime(a), Value::DateTime(b)) => Value::Bool(a < b),
            _ => Value::Bool(false),
        }
    });

    // --- Greater Or Equal (>=) ---
    env.register_native(">=", cmp_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Bool(a >= b),
            (Value::Int(a), Value::Float(b)) => Value::Bool((*a as f64) >= *b),
            (Value::Float(a), Value::Int(b)) => Value::Bool(*a >= (*b as f64)),
            (Value::Float(a), Value::Float(b)) => Value::Bool(a >= b),
            (Value::DateTime(a), Value::DateTime(b)) => Value::Bool(a >= b),
            _ => Value::Bool(false),
        }
    });

    // --- Less Or Equal (<=) ---
    env.register_native("<=", cmp_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Bool(a <= b),
            (Value::Int(a), Value::Float(b)) => Value::Bool((*a as f64) <= *b),
            (Value::Float(a), Value::Int(b)) => Value::Bool(*a <= (*b as f64)),
            (Value::Float(a), Value::Float(b)) => Value::Bool(a <= b),
            (Value::DateTime(a), Value::DateTime(b)) => Value::Bool(a <= b),
            _ => Value::Bool(false),
        }
    });

    // --- Equal (=) ---
    let eq_ty = StaticType::Function(Box::new(Signature {
        params: StaticType::Tuple(vec![StaticType::Any, StaticType::Any]),
        ret: StaticType::Bool,
    }));
    env.register_native("=", eq_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        // Simple equality check.
        // Note: Floating point equality is tricky, but we follow standard behavior for now.
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Bool(a == b),
            (Value::Float(a), Value::Float(b)) => Value::Bool((a - b).abs() < f64::EPSILON),
            (Value::Int(a), Value::Float(b)) => Value::Bool((*a as f64 - b).abs() < f64::EPSILON),
            (Value::Float(a), Value::Int(b)) => Value::Bool((a - *b as f64).abs() < f64::EPSILON),
            (Value::Text(a), Value::Text(b)) => Value::Bool(a == b),
            (Value::Bool(a), Value::Bool(b)) => Value::Bool(a == b),
            (Value::Keyword(a), Value::Keyword(b)) => Value::Bool(a == b),
            (Value::DateTime(a), Value::DateTime(b)) => Value::Bool(a == b),
            (Value::Void, Value::Void) => Value::Bool(true),
            _ => Value::Bool(false),
        }
    });

    // --- Not Equal (<>) ---
    env.register_native("<>", eq_ty, true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Bool(a != b),
            (Value::Float(a), Value::Float(b)) => Value::Bool((a - b).abs() >= f64::EPSILON),
            (Value::Int(a), Value::Float(b)) => Value::Bool((*a as f64 - b).abs() >= f64::EPSILON),
            (Value::Float(a), Value::Int(b)) => Value::Bool((a - *b as f64).abs() >= f64::EPSILON),
            (Value::Text(a), Value::Text(b)) => Value::Bool(a != b),
            (Value::Bool(a), Value::Bool(b)) => Value::Bool(a != b),
            (Value::Keyword(a), Value::Keyword(b)) => Value::Bool(a != b),
            (Value::DateTime(a), Value::DateTime(b)) => Value::Bool(a != b),
            (Value::Void, Value::Void) => Value::Bool(false),
            _ => Value::Bool(true),
        }
    });
}

fn register_logic(env: &Environment) {
    // --- Not (not) ---
    let not_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Bool]),
            ret: StaticType::Bool,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int]),
            ret: StaticType::Int,
        },
    ]);
    env.register_native("not", not_ty, true, |args| {
        if args.len() != 1 {
            return Value::Void;
        }
        match &args[0] {
            Value::Bool(b) => Value::Bool(!b),
            Value::Int(i) => Value::Int(!i), // Bitwise NOT
            _ => Value::Void,
        }
    });

    // --- And (and) ---
    let logic_op_ty = StaticType::FunctionOverloads(vec![
        Signature {
            params: StaticType::Tuple(vec![StaticType::Bool, StaticType::Bool]),
            ret: StaticType::Bool,
        },
        Signature {
            params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
            ret: StaticType::Int,
        },
    ]);
    env.register_native("and", logic_op_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Bool(a), Value::Bool(b)) => Value::Bool(*a && *b),
            (Value::Int(a), Value::Int(b)) => Value::Int(a & b),
            _ => Value::Void,
        }
    });

    // --- Or (or) ---
    env.register_native("or", logic_op_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Bool(a), Value::Bool(b)) => Value::Bool(*a || *b),
            (Value::Int(a), Value::Int(b)) => Value::Int(a | b),
            _ => Value::Void,
        }
    });

    // --- Xor (xor) ---
    env.register_native("xor", logic_op_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Bool(a), Value::Bool(b)) => Value::Bool(*a ^ *b),
            (Value::Int(a), Value::Int(b)) => Value::Int(a ^ b),
            _ => Value::Void,
        }
    });

    // --- Shift Left (<<) ---
    let shift_ty = StaticType::Function(Box::new(Signature {
        params: StaticType::Tuple(vec![StaticType::Int, StaticType::Int]),
        ret: StaticType::Int,
    }));
    env.register_native("<<", shift_ty.clone(), true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Int(a << b),
            _ => Value::Void,
        }
    });

    // --- Shift Right (>>) ---
    env.register_native(">>", shift_ty, true, |args| {
        if args.len() != 2 {
            return Value::Void;
        }
        match (&args[0], &args[1]) {
            (Value::Int(a), Value::Int(b)) => Value::Int(a >> b),
            _ => Value::Void,
        }
    });
}