#include "UserScript.h"
#include "UserScriptRequire.h"
#include <algorithm>
#include <span>
#include <utility>

using interpreter = decltype(scripting::prepare_interpreter({}));
using namespace scripting;

struct fn_array final : public scripting::function_impl {
	const int32_t size_limit;
	const bool can_contain_arrays;
	
	fn_array(int32_t _size_limit, bool _can_contain_arrays)
		: size_limit(_size_limit)
		, can_contain_arrays(_can_contain_arrays)
	{}
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		array ary;
		if(not can_contain_arrays && details::NoArrays<0>{}.verify(self, n)) {
			error = script_error{
				.message = "/array: arrays cannot contain other arrays"
			};
			return std::nullopt;
		}
		
		if(n.size() > std::max<int32_t>(0, size_limit)) {
			error = script_error{
				.message = "/array: arrays exceeds max size"
			};
			return std::nullopt;
		}
		
		std::transform(n.rbegin(), n.rend(), std::back_inserter(ary.value), [&](argument& arg){
			if(std::holds_alternative<scripting::script_value>(arg)) {
				return std::get<scripting::script_value>(arg);
			} else {
				return self->resolve(std::get<scripting::script_variable>(arg).name);
			}
		});
		
		return ary;
	}
	
	~fn_array() final = default;
};

struct fn_array_reverse final : public scripting::function_impl {
	fn_array_reverse() = default;
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		using verifier = Verify<details::TypeVerifier<0, array>>;
		
		if(verifier{}.verify(self, n)) {
			error = script_error{
				.message = "/array_reverse takes exactly 1 argument of type array"
			};
			return std::nullopt;
		}
		
		auto& arg = n.front();
		script_value target;
		
		if(std::holds_alternative<scripting::script_value>(arg)) {
			target = std::get<scripting::script_value>(arg);
		} else {
			target = self->resolve(std::get<scripting::script_variable>(arg).name);
		}
		
		auto& ary = std::get<array>(target);
		
		std::reverse(ary.value.begin(), ary.value.end());
		
		return target;
	}
	
	~fn_array_reverse() final = default;
};

struct fn_array_append final : public scripting::function_impl {
	const std::string name;
	const int32_t size_limit;
	const bool can_contain_arrays;
	
	fn_array_append(std::string _name, int32_t _size_limit, bool _can_contain_arrays)
		: name(std::move(_name))
		, size_limit(_size_limit)
		, can_contain_arrays(_can_contain_arrays)
	{}
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		using verifier = Verify<
		    details::TypeVerifier<0, array>,
			details::VariableVerifier<0>,
			details::SizeAtLeast<1>
		>;
		
		if(verifier{}.verify(self, n) && can_contain_arrays || details::NoArrays<1>{}.verify(self, n)) {
			error = script_error{
				.message = "/array_append: must provide an array variable as first argument"
			};
			return std::nullopt;
		}
		
		auto target = self->getValue(std::get<script_variable>(n.back()).name);
		n.pop_back();
		
		auto& ary = std::get<array>(target.value().get()).value;
		
		if(n.size() + ary.size() > std::max<int32_t>(0, size_limit)) {
			error = script_error{
				.message = "/array_append: array would exceed size limit"
			};
			return script_value{0};
		}
		
		std::transform(n.rbegin(), n.rend(), std::back_inserter(ary), [&](argument& arg){
			if(std::holds_alternative<scripting::script_value>(arg)) {
				return std::get<scripting::script_value>(arg);
			} else {
				return self->resolve(std::get<scripting::script_variable>(arg).name);
			}
		});
		
		return script_value{1};
	}
	
	~fn_array_append() final = default;
};

struct fn_array_prepend final : public scripting::function_impl {
	const std::string name;
	const int32_t size_limit;
	const bool can_contain_arrays;
	
	fn_array_prepend(std::string _name, int32_t _size_limit, bool _can_contain_arrays)
		: name(std::move(_name))
		, size_limit(_size_limit)
		, can_contain_arrays(_can_contain_arrays)
	{}
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		using verifier = Verify<
			details::TypeVerifier<0, array>,
			details::VariableVerifier<0>,
			details::SizeEquals<2>
		>;
		
		if((verifier{}.verify(self, n)) && (can_contain_arrays || details::NoArrays<1>{}.verify(self, n))) {
			error = script_error{
				.message = "/array_append: must provide an array variable as first argument"
			};
			return std::nullopt;
		}
		
		auto target = self->getValue(std::get<script_variable>(n.back()).name);
		n.pop_back();
		
		auto& ary = std::get<array>(target.value().get()).value;
		
		if(n.size() + ary.size() > std::max<int32_t>(0, size_limit)) {
			error = script_error{
				.message = name + ": array would exceed size limit"
			};
			return script_value{0};
		}
		
		if(std::holds_alternative<scripting::script_value>(n.front())) {
			ary.push_front(std::get<scripting::script_value>(n.front()));
		} else {
			ary.push_front(self->resolve(std::get<scripting::script_variable>(n.front()).name));
		}
		
		return script_value{1};
	}
	
	~fn_array_prepend() final = default;
};

struct fn_array_pop final : public scripting::function_impl {
	std::string name;
	
	fn_array_pop(std::string _name) : name(std::move(_name)) {}
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		using verifier = Verify<
			details::TypeVerifier<0, array>,
			details::VariableVerifier<0>,
			details::SizeEquals<1>
		>;
		
		if(verifier{}.verify(self, n)) {
			error = script_error{
				.message = name + " takes exactly 1 argument of type array"
			};
			return std::nullopt;
		}
		
		auto& arg = n.front();
		script_value target;
		
		if(std::holds_alternative<scripting::script_value>(arg)) {
			target = std::get<scripting::script_value>(arg);
		} else {
			target = self->resolve(std::get<scripting::script_variable>(arg).name);
		}
		
		auto& ary = std::get<array>(target);
		
		if(ary.value.empty()) {
			return {null{}};
		}
		
		auto value = ary.value.back();
		
		ary.value.pop_back();
		
		return value;
	}
	
	~fn_array_pop() final = default;
};

struct fn_array_size final : public scripting::function_impl {
	fn_array_size() = default;
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {using verifier = Verify<
			details::TypeVerifier<0, array>,
			details::VariableVerifier<0>,
			details::SizeEquals<1>
		>;
		
		if(verifier{}.verify(self, n)) {
			error = script_error{
				.message = "/array_size takes exactly 1 argument of type array"
			};
			return std::nullopt;
		}
		
		auto& arg = n.front();
		script_value target;
		
		if(std::holds_alternative<scripting::script_value>(arg)) {
			target = std::get<scripting::script_value>(arg);
		} else {
			target = self->resolve(std::get<scripting::script_variable>(arg).name);
		}
		
		return static_cast<int32_t>(std::get<array>(target).value.size());
	}
	
	~fn_array_size() final = default;
};

struct fn_array_index final : public scripting::function_impl {
	fn_array_index() = default;
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		if(n.size() != 2) {
			error = script_error{
				.message = "/array_size takes exactly 2 argument of type (array, integer)"
			};
			return std::nullopt;
		}
		
		using verifier = Verify<
			details::TypeVerifier<0, array>,
			details::VariableVerifier<0>,
			details::TypeVerifier<1, int32_t>
		>;
		
		if(verifier{}.verify(self, n)) {
			error = script_error{
				.message = "/array_index takes exactly 2 argument of type (array, integer)"
			};
			return std::nullopt;
		}
		
		auto& arg = n.back();
		script_value target;
		
		if(std::holds_alternative<scripting::script_value>(arg)) {
			target = std::get<scripting::script_value>(arg);
		} else {
			target = self->resolve(std::get<scripting::script_variable>(arg).name);
		}
		
		auto& idx_arg = n.front();
		script_value idx;
		
		if(std::holds_alternative<scripting::script_value>(idx_arg)) {
			idx = std::get<scripting::script_value>(idx_arg);
		} else {
			idx = self->resolve(std::get<scripting::script_variable>(idx_arg).name);
		}
		
		if(static_cast<int32_t>(std::get<array>(target).value.size()) <= std::get<int32_t>(idx)) {
			error = script_error{
				.message = "/array_index index must be smaller that the array size, the first element of the array has index 0"
			};
			return std::nullopt;
		}
		
		if(std::get<int32_t>(idx) < 0) {
			error = script_error{
				.message = "/array_index index must be 0 or more"
			};
			return std::nullopt;
		}
		
		return std::get<array>(target).value.at(static_cast<size_t>(std::get<int32_t>(idx)));
	}
	
	~fn_array_index() final = default;
};

struct fn_array_set final : public scripting::function_impl {
	fn_array_set() = default;
	
	std::optional<script_value> apply(UserScript* self, std::vector<argument> n, std::optional<script_error>& error) final {
		if(n.size() != 3) {
			error = script_error{
				.message = "/array_set takes exactly 3 argument of type (array, integer, value), provided a different amount"
			};
			return std::nullopt;
		}
		
		auto& arg = n.back();
		
		if(std::holds_alternative<scripting::script_value>(arg)) {
			error = script_error{
				.message = "/array_set takes exactly 3 argument of type (array, integer, value), the array needs to be a variable"
			};
			return std::nullopt;
		}
		
		auto target = self->getValue(std::get<scripting::script_variable>(arg).name);
		
		if(not target) {
			error = script_error{
				.message = "/array_set takes exactly 3 argument of type (array, integer, value), provided array variable is undefined"
			};
			return std::nullopt;
		}
		
		if(not std::holds_alternative<array>(target.value().get())) {
			error = script_error{
				.message = "/array_set takes exactly 1 argument of type array followed by an integer, argument 1 is not an array"
			};
			return std::nullopt;
		}
		
		
		auto& concrete_target = std::get<array>(target.value().get());
		
		auto& idx_arg = n[1];
		script_value idx;
		
		if(std::holds_alternative<scripting::script_value>(idx_arg)) {
			idx = std::get<scripting::script_value>(idx_arg);
		} else {
			idx = self->resolve(std::get<scripting::script_variable>(idx_arg).name);
		}
		
		if(not std::holds_alternative<int32_t>(idx)) {
			error = script_error{
				.message = "/array_set takes exactly 1 argument of type array followed by an integer, argument 2 is not an integer"
			};
			return std::nullopt;
		}
		
		if(static_cast<int32_t>(concrete_target.value.size()) <= std::get<int32_t>(idx)) {
			error = script_error{
				.message = "/array_set index must be smaller that the array size, the first element of the array has index 0"
			};
			return std::nullopt;
		}
		
		if(std::get<int32_t>(idx) < 0) {
			error = script_error{
				.message = "/array_set index must be 0 or more"
			};
			return std::nullopt;
		}
		
		auto& value_arg = n.front();
		script_value value;
		
		if(std::holds_alternative<scripting::script_value>(value_arg)) {
			value = std::get<scripting::script_value>(value_arg);
		} else {
			value = self->resolve(std::get<scripting::script_variable>(value_arg).name);
		}
		
		concrete_target.value.at(std::get<int32_t>(idx)) = value;
		
		return concrete_target.value[std::get<int32_t>(idx)];
	}
	
	~fn_array_set() final = default;
};

namespace scripting {
	interpreter register_array_lib(interpreter target, bool recursive_arrays, int32_t size_limit) {
		target->registerFunction("array", std::make_unique<fn_array>(size_limit, recursive_arrays));
		target->registerFunction("array_reverse", std::make_unique<fn_array_reverse>());
		target->registerFunction("array_append", std::make_unique<fn_array_append>("array_append", size_limit, recursive_arrays));
		target->registerFunction("array_push", std::make_unique<fn_array_append>("array_push", size_limit, recursive_arrays));
		target->registerFunction("array_pop", std::make_unique<fn_array_pop>("array_pop"));
		target->registerFunction("array_size", std::make_unique<fn_array_size>());
		target->registerFunction("array_index", std::make_unique<fn_array_index>());
		target->registerFunction("array_set", std::make_unique<fn_array_set>());
		target->registerFunction("queue_enqueue", std::make_unique<fn_array_prepend>("queue_enqueue", size_limit, recursive_arrays));
		target->registerFunction("queue_dequeue", std::make_unique<fn_array_pop>("queue_dequeue"));
		return std::move(target);
	}
}