//
//  ColecoVision.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 23/02/2018.
//  Copyright 2018 Thomas Harte. All rights reserved.
//

#include "ColecoVision.hpp"

#include "../../Processors/Z80/Z80.hpp"

#include "../../Components/9918/9918.hpp"
#include "../../Components/AY38910/AY38910.hpp"	// For the Super Game Module.
#include "../../Components/SN76489/SN76489.hpp"

#include "../MachineTypes.hpp"
#include "../../Configurable/Configurable.hpp"

#include "../../Configurable/StandardOptions.hpp"
#include "../../ClockReceiver/ForceInline.hpp"
#include "../../ClockReceiver/JustInTime.hpp"

#include "../../Outputs/Speaker/Implementation/CompoundSource.hpp"
#include "../../Outputs/Speaker/Implementation/LowpassSpeaker.hpp"

#include "../../Analyser/Dynamic/ConfidenceCounter.hpp"

namespace {
constexpr int sn76489_divider = 2;
}

namespace Coleco {
namespace Vision {

class Joystick: public Inputs::ConcreteJoystick {
public:
	Joystick() :
		ConcreteJoystick({
			Input(Input::Up),
			Input(Input::Down),
			Input(Input::Left),
			Input(Input::Right),

			Input(Input::Fire, 0),
			Input(Input::Fire, 1),

			Input('0'),	Input('1'),	Input('2'),
			Input('3'),	Input('4'),	Input('5'),
			Input('6'),	Input('7'),	Input('8'),
			Input('9'),	Input('*'),	Input('#'),
		}) {}

	void did_set_input(const Input &digital_input, bool is_active) final {
		switch(digital_input.type) {
			default: return;

			case Input::Key:
				if(!is_active) keypad_ |= 0xf;
				else {
					uint8_t mask = 0xf;
					switch(digital_input.info.key.symbol) {
						case '8':	mask = 0x1;		break;
						case '4':	mask = 0x2;		break;
						case '5':	mask = 0x3;		break;
						case '7':	mask = 0x5;		break;
						case '#':	mask = 0x6;		break;
						case '2':	mask = 0x7;		break;
						case '*':	mask = 0x9;		break;
						case '0':	mask = 0xa;		break;
						case '9':	mask = 0xb;		break;
						case '3':	mask = 0xc;		break;
						case '1':	mask = 0xd;		break;
						case '6':	mask = 0xe;		break;
						default: break;
					}
					keypad_ = (keypad_ & 0xf0) | mask;
				}
			break;

			case Input::Up:		if(is_active) direction_ &= ~0x01; else direction_ |= 0x01;	break;
			case Input::Right:	if(is_active) direction_ &= ~0x02; else direction_ |= 0x02;	break;
			case Input::Down:	if(is_active) direction_ &= ~0x04; else direction_ |= 0x04;	break;
			case Input::Left:	if(is_active) direction_ &= ~0x08; else direction_ |= 0x08;	break;
			case Input::Fire:
				switch(digital_input.info.control.index) {
					default: break;
					case 0:	if(is_active) direction_ &= ~0x40; else direction_ |= 0x40;	break;
					case 1:	if(is_active) keypad_ &= ~0x40; else keypad_ |= 0x40;		break;
				}
			break;
		}
	}

	uint8_t get_direction_input() {
		return direction_;
	}

	uint8_t get_keypad_input() {
		return keypad_;
	}

private:
	uint8_t direction_ = 0xff;
	uint8_t keypad_ = 0x7f;
};

class ConcreteMachine:
	public Machine,
	public CPU::Z80::BusHandler,
	public Configurable::Device,
	public MachineTypes::TimedMachine,
	public MachineTypes::ScanProducer,
	public MachineTypes::AudioProducer,
	public MachineTypes::JoystickMachine {

public:
	ConcreteMachine(const Analyser::Static::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
		z80_(*this),
		sn76489_(TI::SN76489::Personality::SN76489, audio_queue_, sn76489_divider),
		ay_(GI::AY38910::Personality::AY38910, audio_queue_),
		mixer_(sn76489_, ay_),
		speaker_(mixer_) {
		speaker_.set_input_rate(3579545.0f / float(sn76489_divider));
		set_clock_rate(3579545);
		joysticks_.emplace_back(new Joystick);
		joysticks_.emplace_back(new Joystick);

		constexpr ROM::Name rom_name = ROM::Name::ColecoVisionBIOS;
		const ROM::Request request(rom_name);
		auto roms = rom_fetcher(request);
		if(!request.validate(roms)) {
			throw ROMMachine::Error::MissingROMs;
		}
		bios_ = roms.find(rom_name)->second;

		if(!target.media.cartridges.empty()) {
			const auto &segment = target.media.cartridges.front()->get_segments().front();
			cartridge_ = segment.data;
			if(cartridge_.size() >= 32768)
				cartridge_address_limit_ = 0xffff;
			else
				cartridge_address_limit_ = uint16_t(0x8000 + cartridge_.size() - 1);

			if(cartridge_.size() > 32768) {
				// Ensure the cartrige is a multiple of 16kb in size, as that won't
				// be checked when paging.
				const size_t extension = (16384 - (cartridge_.size() & 16383)) % 16384;
				cartridge_.resize(cartridge_.size() + extension);

				cartridge_pages_[0] = &cartridge_[cartridge_.size() - 16384];
				cartridge_pages_[1] = cartridge_.data();
				is_megacart_ = true;
			} else {
				// Ensure at least 32kb is allocated to the cartrige so that
				// reads are never out of bounds.
				cartridge_.resize(32768);

				cartridge_pages_[0] = cartridge_.data();
				cartridge_pages_[1] = cartridge_.data() + 16384;
				is_megacart_ = false;
			}
		}

		// ColecoVisions have composite output only.
		vdp_->set_display_type(Outputs::Display::DisplayType::CompositeColour);
	}

	~ConcreteMachine() {
		audio_queue_.flush();
	}

	const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() final {
		return joysticks_;
	}

	void set_scan_target(Outputs::Display::ScanTarget *scan_target) final {
		vdp_.last_valid()->set_scan_target(scan_target);
	}

	Outputs::Display::ScanStatus get_scaled_scan_status() const final {
		return vdp_.last_valid()->get_scaled_scan_status();
	}

	void set_display_type(Outputs::Display::DisplayType display_type) final {
		vdp_.last_valid()->set_display_type(display_type);
	}

	Outputs::Display::DisplayType get_display_type() const final {
		return vdp_.last_valid()->get_display_type();
	}

	Outputs::Speaker::Speaker *get_speaker() final {
		return &speaker_;
	}

	void run_for(const Cycles cycles) final {
		z80_.run_for(cycles);
	}

	// MARK: Z80::BusHandler
	forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
		// The SN76489 will use its ready line to trigger the Z80's wait, which will add
		// thirty-one (!) cycles when accessed. M1 cycles are extended by a single cycle.
		// This code works out the delay up front in order to simplify execution flow, though
		// technically this is a little duplicative.
		HalfCycles penalty(0);
		if(cycle.operation == CPU::Z80::PartialMachineCycle::Output && ((*cycle.address >> 5) & 7) == 7) {
			penalty = HalfCycles(62);
		} else if(cycle.operation == CPU::Z80::PartialMachineCycle::ReadOpcode) {
			penalty = HalfCycles(2);
		}
		const HalfCycles length = cycle.length + penalty;

		if(vdp_ += length) {
			z80_.set_non_maskable_interrupt_line(vdp_->get_interrupt_line());
		}
		time_since_sn76489_update_ += length;

		// Act only if necessary.
		if(cycle.is_terminal()) {
			uint16_t address = cycle.address ? *cycle.address : 0x0000;
			switch(cycle.operation) {
				case CPU::Z80::PartialMachineCycle::ReadOpcode:
					if(!address) pc_zero_accesses_++;
					[[fallthrough]];
				case CPU::Z80::PartialMachineCycle::Read:
					if(address < 0x2000) {
						if(super_game_module_.replace_bios) {
							*cycle.value = super_game_module_.ram[address];
						} else {
							*cycle.value = bios_[address];
						}
					} else if(super_game_module_.replace_ram && address < 0x8000) {
						*cycle.value = super_game_module_.ram[address];
					} else if(address >= 0x6000 && address < 0x8000) {
						*cycle.value = ram_[address & 1023];
					} else if(address >= 0x8000 && address <= cartridge_address_limit_) {
						if(is_megacart_ && address >= 0xffc0) {
							page_megacart(address);
						}
						*cycle.value = cartridge_pages_[(address >> 14)&1][address&0x3fff];
					} else {
						*cycle.value = 0xff;
					}
				break;

				case CPU::Z80::PartialMachineCycle::Write:
					if(super_game_module_.replace_bios && address < 0x2000) {
						super_game_module_.ram[address] = *cycle.value;
					} else if(super_game_module_.replace_ram && address >= 0x2000 && address < 0x8000) {
						super_game_module_.ram[address] = *cycle.value;
					} else if(address >= 0x6000 && address < 0x8000) {
						ram_[address & 1023] = *cycle.value;
					} else if(is_megacart_ && address >= 0xffc0) {
						page_megacart(address);
					}
				break;

				case CPU::Z80::PartialMachineCycle::Input:
					switch((address >> 5) & 7) {
						case 5:
							*cycle.value = vdp_->read(address);
							z80_.set_non_maskable_interrupt_line(vdp_->get_interrupt_line());
						break;

						case 7: {
							const std::size_t joystick_id = (address&2) >> 1;
							Joystick *joystick = static_cast<Joystick *>(joysticks_[joystick_id].get());
							if(joysticks_in_keypad_mode_) {
								*cycle.value = joystick->get_keypad_input();
							} else {
								*cycle.value = joystick->get_direction_input();
							}

							// Hitting exactly the recommended joypad input port is an indicator that
							// this really is a ColecoVision game. The BIOS won't do this when just waiting
							// to start a game (unlike accessing the VDP and SN).
							if((address&0xfc) == 0xfc) confidence_counter_.add_hit();
						} break;

						default:
							switch(address&0xff) {
								default: *cycle.value = 0xff; break;
								case 0x52:
									// Read AY data.
									update_audio();
									*cycle.value = GI::AY38910::Utility::read(ay_);
								break;
							}
						break;
					}
				break;

				case CPU::Z80::PartialMachineCycle::Output: {
					const int eighth = (address >> 5) & 7;
					switch(eighth) {
						case 4: case 6:
							joysticks_in_keypad_mode_ = eighth == 4;
						break;

						case 5:
							vdp_->write(address, *cycle.value);
							z80_.set_non_maskable_interrupt_line(vdp_->get_interrupt_line());
						break;

						case 7:
							update_audio();
							sn76489_.write(*cycle.value);
						break;

						default:
							// Catch Super Game Module accesses; it decodes more thoroughly.
							switch(address&0xff) {
								default: break;
								case 0x7f:
									super_game_module_.replace_bios = !((*cycle.value)&0x2);
								break;
								case 0x50:
									// Set AY address.
									update_audio();
									GI::AY38910::Utility::select_register(ay_, *cycle.value);
								break;
								case 0x51:
									// Set AY data.
									update_audio();
									GI::AY38910::Utility::write_data(ay_, *cycle.value);
								break;
								case 0x53:
									super_game_module_.replace_ram = !!((*cycle.value)&0x1);
								break;
							}
						break;
					}
				} break;

				default: break;
			}
		}

		return penalty;
	}

	void flush_output(int outputs) final {
		if(outputs & Output::Video) {
			vdp_.flush();
		}
		if(outputs & Output::Audio) {
			update_audio();
			audio_queue_.perform();
		}
	}

	float get_confidence() final {
		if(pc_zero_accesses_ > 1) return 0.0f;
		return confidence_counter_.get_confidence();
	}

	// MARK: - Configuration options.
	std::unique_ptr<Reflection::Struct> get_options() const final {
		auto options = std::make_unique<Options>(Configurable::OptionsType::UserFriendly);
		options->output = get_video_signal_configurable();
		return options;
	}

	void set_options(const std::unique_ptr<Reflection::Struct> &str) final {
		const auto options = dynamic_cast<Options *>(str.get());
		set_video_signal_configurable(options->output);
	}

private:
	inline void page_megacart(uint16_t address) {
		const std::size_t selected_start = (size_t(address&63) << 14) % cartridge_.size();
		cartridge_pages_[1] = &cartridge_[selected_start];
	}
	inline void update_audio() {
		speaker_.run_for(audio_queue_, time_since_sn76489_update_.divide_cycles(Cycles(sn76489_divider)));
	}

	CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
	JustInTimeActor<TI::TMS::TMS9918<TI::TMS::Personality::TMS9918A>> vdp_;

	Concurrency::AsyncTaskQueue<false> audio_queue_;
	TI::SN76489 sn76489_;
	GI::AY38910::AY38910<false> ay_;
	Outputs::Speaker::CompoundSource<TI::SN76489, GI::AY38910::AY38910<false>> mixer_;
	Outputs::Speaker::PullLowpass<Outputs::Speaker::CompoundSource<TI::SN76489, GI::AY38910::AY38910<false>>> speaker_;

	std::vector<uint8_t> bios_;
	std::vector<uint8_t> cartridge_;
	uint8_t *cartridge_pages_[2];
	uint8_t ram_[1024];
	bool is_megacart_ = false;
	uint16_t cartridge_address_limit_ = 0;
	struct {
		bool replace_bios = false;
		bool replace_ram = false;
		uint8_t ram[32768];
	} super_game_module_;

	std::vector<std::unique_ptr<Inputs::Joystick>> joysticks_;
	bool joysticks_in_keypad_mode_ = false;

	HalfCycles time_since_sn76489_update_;

	Analyser::Dynamic::ConfidenceCounter confidence_counter_;
	int pc_zero_accesses_ = 0;
};

}
}

using namespace Coleco::Vision;

std::unique_ptr<Machine> Machine::ColecoVision(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
	return std::make_unique<ConcreteMachine>(*target, rom_fetcher);
}