#include "vm/builtins.h"

#include <stdio.h>

static void print_val(struct l2_vm *vm, struct l2_io_writer *out, struct l2_vm_value *val) {
	switch (l2_vm_value_type(val)) {
		case L2_VAL_TYPE_NONE:
			l2_io_printf(out, "(none)");
			break;

		case L2_VAL_TYPE_ATOM:
			if (val->atom == vm->values[vm->ktrue].atom) {
				l2_io_printf(out, "(true)");
			} else if (val->atom == vm->values[vm->kfalse].atom) {
				l2_io_printf(out, "(false)");
			} else {
				l2_io_printf(out, "(atom %u)", val->atom);
			}
			break;

		case L2_VAL_TYPE_REAL:
			l2_io_printf(out, "%g", val->real);
			break;

		case L2_VAL_TYPE_BUFFER:
			if (val->buffer != NULL) {
				out->write(out, val->buffer->data, val->buffer->len);
			}
			break;

		case L2_VAL_TYPE_ARRAY:
			if (val->array == NULL) {
				out->write(out, "[]", 2);
				break;
			}

			out->write(out, "[", 1);
			for (size_t i = 0; i < val->array->len; ++i) {
				if (i != 0) {
					out->write(out, " ", 1);
				}

				print_val(vm, out, &vm->values[val->array->data[i]]);
			}
			out->write(out, "]", 1);
			break;

		case L2_VAL_TYPE_NAMESPACE:
			l2_io_printf(out, "(namespace)");
			break;

		case L2_VAL_TYPE_FUNCTION:
		case L2_VAL_TYPE_CFUNCTION:
			l2_io_printf(out, "(function)");
			break;

		case L2_VAL_TYPE_ERROR:
			l2_io_printf(out, "(error: %s)", val->error);
			break;

		case L2_VAL_TYPE_CONTINUATION:
			l2_io_printf(out, "(continuation)");
			break;
	}
}

l2_word l2_builtin_add(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc < 1) {
		return 0;
	}

	struct l2_vm_value *val = &vm->values[argv[0]];
	if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
		return l2_vm_type_error(vm, val);
	}

	double sum = val->real;
	for (l2_word i = 1; i < argc; ++i) {
		val = &vm->values[argv[i]];
		if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
			return l2_vm_type_error(vm, val);
		}

		sum += val->real;
	}

	l2_word id = l2_vm_alloc(vm, L2_VAL_TYPE_REAL, 0);
	vm->values[id].real = sum;
	return id;
}

l2_word l2_builtin_sub(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc < 1) {
		return 0;
	}

	struct l2_vm_value *val = &vm->values[argv[0]];
	if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
		return l2_vm_type_error(vm, val);
	}

	double sum = val->real;
	for (l2_word i = 1; i < argc; ++i) {
		val = &vm->values[argv[i]];
		if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
			return l2_vm_type_error(vm, val);
		}

		sum -= val->real;
	}

	l2_word id = l2_vm_alloc(vm, L2_VAL_TYPE_REAL, 0);
	vm->values[id].real = sum;
	return id;
}

l2_word l2_builtin_mul(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc < 1) {
		return 0;
	}

	struct l2_vm_value *val = &vm->values[argv[0]];
	if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
		return l2_vm_type_error(vm, val);
	}

	double sum = val->real;
	for (l2_word i = 1; i < argc; ++i) {
		val = &vm->values[argv[i]];
		if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
			return l2_vm_type_error(vm, val);
		}

		sum *= val->real;
	}

	l2_word id = l2_vm_alloc(vm, L2_VAL_TYPE_REAL, 0);
	vm->values[id].real = sum;
	return id;
}

l2_word l2_builtin_div(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc < 1) {
		return 0;
	}

	struct l2_vm_value *val = &vm->values[argv[0]];
	if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
		return l2_vm_type_error(vm, val);
	}

	double sum = val->real;
	for (l2_word i = 1; i < argc; ++i) {
		val = &vm->values[argv[i]];
		if (l2_vm_value_type(val) != L2_VAL_TYPE_REAL) {
			return l2_vm_type_error(vm, val);
		}

		sum /= val->real;
	}

	l2_word id = l2_vm_alloc(vm, L2_VAL_TYPE_REAL, 0);
	vm->values[id].real = sum;
	return id;
}

l2_word l2_builtin_eq(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc < 2) {
		return l2_vm_error(vm, "Expected at least 2 arguments");
	}

	for (l2_word i = 1; i < argc; ++i) {
		if (argv[i - 1] == argv[i]) continue;
		struct l2_vm_value *a = &vm->values[argv[i - 1]];
		struct l2_vm_value *b = &vm->values[argv[i]];
		if (a->flags != b->flags) {
			return vm->kfalse;
		}

		enum l2_value_type typ = l2_vm_value_type(a);
		if (typ == L2_VAL_TYPE_ATOM) {
			if (a->atom != b->atom) {
				return vm->kfalse;
			}
		} else if (typ == L2_VAL_TYPE_REAL) {
			if (a->real != b->real) {
				return vm->kfalse;
			}
		} else if (typ == L2_VAL_TYPE_BUFFER) {
			if (a->buffer == NULL && b->buffer == NULL) continue;
			if (a->buffer == NULL || b->buffer == NULL) {
				return vm->kfalse;
			}

			if (a->buffer->len != b->buffer->len) {
				return vm->kfalse;
			}

			if (memcmp(a->buffer->data, b->buffer->data, a->buffer->len) != 0) {
				return vm->kfalse;
			}
		} else {
			return vm->kfalse;
		}
	}

	return vm->ktrue;
}

l2_word l2_builtin_neq(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	l2_word ret_id = l2_builtin_eq(vm, argc, argv);
	if (ret_id == vm->ktrue) {
		return vm->kfalse;
	} else if (ret_id == vm->kfalse) {
		return vm->ktrue;
	} else {
		return ret_id;
	}
}

#define X(name, op) \
l2_word name(struct l2_vm *vm, l2_word argc, l2_word *argv) { \
	if (argc < 2) { \
		return l2_vm_error(vm, "Expected at least 2 arguments"); \
	} \
	struct l2_vm_value *lhs = &vm->values[argv[0]]; \
	if (l2_vm_value_type(lhs) != L2_VAL_TYPE_REAL) { \
		return l2_vm_type_error(vm, lhs); \
	} \
	for (l2_word i = 1; i < argc; ++i) { \
		struct l2_vm_value *rhs = &vm->values[argv[i]]; \
		if (l2_vm_value_type(rhs) != L2_VAL_TYPE_REAL) { \
			return l2_vm_type_error(vm, rhs); \
		} \
		if (!(lhs->real op rhs->real)) { \
			return vm->kfalse; \
		} \
		lhs = rhs; \
	} \
	return vm->ktrue; \
}
X(l2_builtin_lt, <)
X(l2_builtin_lteq, <=)
X(l2_builtin_gt, >)
X(l2_builtin_gteq, >=)
#undef X

l2_word l2_builtin_print(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	for (size_t i = 0; i < argc; ++i) {
		if (i != 0) {
			vm->std_output->write(vm->std_output, " ", 1);
		}

		struct l2_vm_value *val = &vm->values[argv[i]];
		print_val(vm, vm->std_output, val);
	}

	vm->std_output->write(vm->std_output, "\n", 1);
	return 0;
}

l2_word l2_builtin_len(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc != 1) {
		return l2_vm_error(vm, "Expected 1 argument");
	}

	l2_word ret_id = l2_vm_alloc(vm, L2_VAL_TYPE_REAL, 0);
	struct l2_vm_value *ret = &vm->values[ret_id];
	ret->real = 0;

	struct l2_vm_value *val = &vm->values[argv[0]];
	switch (l2_vm_value_type(val)) {
	case L2_VAL_TYPE_NONE:
	case L2_VAL_TYPE_ATOM:
	case L2_VAL_TYPE_REAL:
	case L2_VAL_TYPE_FUNCTION:
	case L2_VAL_TYPE_CFUNCTION:
	case L2_VAL_TYPE_ERROR:
	case L2_VAL_TYPE_CONTINUATION:
		break;

	case L2_VAL_TYPE_BUFFER:
		if (val->buffer) {
			ret->real = val->buffer->len;
		}
		break;

	case L2_VAL_TYPE_ARRAY:
		if (val->array) {
			ret->real = val->array->len;
		}
		break;

	case L2_VAL_TYPE_NAMESPACE:
		if (val->ns) {
			ret->real = val->ns->len;
		}
	}

	return ret_id;
}

l2_word l2_builtin_if(struct l2_vm *vm, l2_word argc, l2_word *argv) {
	if (argc != 2 && argc != 3) {
		return l2_vm_error(vm, "Expected 2 or 3 arguments");
	}

	struct l2_vm_value *cond = &vm->values[argv[0]];

	if (
			l2_vm_value_type(cond) == L2_VAL_TYPE_ATOM &&
			cond->atom == vm->values[vm->ktrue].atom) {
		l2_word ret_id = l2_vm_alloc(vm, L2_VAL_TYPE_CONTINUATION, 0);
		struct l2_vm_value *ret = &vm->values[ret_id];
		ret->cont.call = argv[1];
		ret->cont.arg = 0;
		return ret_id;
	} else if (argc == 3) {
		l2_word ret_id = l2_vm_alloc(vm, L2_VAL_TYPE_CONTINUATION, 0);
		struct l2_vm_value *ret = &vm->values[ret_id];
		ret->cont.call = argv[2];
		ret->cont.arg = 0;
		return ret_id;
	} else {
		return 0;
	}
}