//
//  ADB.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 31/10/2020.
//  Copyright © 2020 Thomas Harte. All rights reserved.
//

#include "ADB.hpp"

#include <cassert>
#include <cstdio>

// TEST.
#include "../../../InstructionSets/M50740/Parser.hpp"
#include "../../../InstructionSets/Disassembler.hpp"

using namespace Apple::IIgs::ADB;

GLU::GLU() : executor_(*this) {}

// MARK: - Configuration.

void GLU::set_is_rom03(bool is_rom03) {
	is_rom03_ = is_rom03;
}

// MARK: - External interface.

uint8_t GLU::get_keyboard_data() {
	// The classic Apple II serial keyboard register:
	// b7:		key strobe.
	// b6–b0:	ASCII code.
	return 0x00;
}

void GLU::clear_key_strobe() {
	// Clears the key strobe of the classic Apple II serial keyboard register.
}

uint8_t GLU::get_any_key_down() {
	// The Apple IIe check-for-any-key-down bit.
	return 0x00;
}

uint8_t GLU::get_mouse_data() {
	// Alternates between returning x and y values.
	//
	// b7: 		1 = button is up; 0 = button is down.
	// b6:		delta sign bit; 1 = negative.
	// b5–b0:	mouse delta.
	return 0x80;
}

uint8_t GLU::get_modifier_status() {
	// b7:		1 = command key pressed; 0 = not.
	// b6:		option key.
	// b5:		1 = modifier key latch has been updated, no key has been pressed; 0 = not.
	// b4:		any numeric keypad key.
	// b3:		a key is down.
	// b2:		caps lock is pressed.
	// b1:		control key.
	// b0:		shift key.
	return 0x00;
}

uint8_t GLU::get_data() {
	printf("ADB get data\n");
	if(!pending_response_.empty()) {
		// A bit yucky, pull from the from the front.
		// This keeps my life simple for now, even though it's inefficient.
		const uint8_t next = pending_response_[0];
		pending_response_.erase(pending_response_.begin());
		return next;
	}

	// b0–2:	number of data bytes to be returned.
	// b3:		1 = a valid service request is pending; 0 = no request pending.
	// b4:		1 = control, command and delete keys have been pressed simultaneously; 0 = they haven't.
	// b5:		1 = control, command and reset have all been pressed together; 0 = they haven't.
	// b6:		1 = ADB controller encountered an error and reset itself; 0 = no error.
	// b7:		1 = ADB has received a response from the addressed ADB device; 0 = no respone.
	return 0x00;
}

uint8_t GLU::get_status() {
	// b7:	1 = mouse data register is full; 0 = empty.
	// b6:	1 = mouse interrupt is enabled.
	// b5:	1 = command/data has valid data.
	// b4:	1 = command/data interrupt is enabled.
	// b3:	1 = keyboard data is full.
	// b2:	1 = keyboard data interrupt is enabled.
	// b1:	1 = mouse x-data is available; 0 = y.
	// b0:	1 = command register is full (set when command is written); 0 = empty (cleared when data is read).
	const uint8_t status =
		(pending_response_.empty() ? 0 : 0x20);	// Data is valid if a response is pending.
//	printf("ADB get status : %02x\n", status);
	return status;
}

void GLU::set_command(uint8_t command) {
	// Accumulate input until a full comamnd is received;
	// the state machine otherwise gets somewhat oversized.
	next_command_.push_back(command);

	// Command dispatch; each entry should do whatever it needs
	// to do and then either: (i) break, if completed; or
	// (ii) return, if awaiting further input.
#define RequireSize(n)	if(next_command_.size() < (n)) return;
	switch(next_command_[0]) {
		case 0x01:	abort();					break;
		case 0x02:	reset_microcontroller();	break;
		case 0x03:	flush_keyboard_buffer();	break;

		case 0x04:	// Set modes.
			RequireSize(2);
			set_modes(modes_ | next_command_[1]);
		break;

		case 0x05:	// Clear modes.
			RequireSize(2);
			set_modes(modes_ & ~next_command_[1]);
		break;

		case 0x06:	// Set configuration bytes
			RequireSize(4);
			set_configuration_bytes(&next_command_[1]);
		break;

		case 0x07:	// Sync.
			RequireSize(is_rom03_ ? 9 : 5);
			set_modes(next_command_[1]);
			set_configuration_bytes(&next_command_[2]);

			// ROM03 seems to expect to send an extra four bytes here,
			// with values 0x20, 0x26, 0x2d, 0x2d.
			// TODO: what does the ROM03-paired ADB GLU do with the extra four bytes?
		break;

		case 0x09:	// Read microcontroller memory.
			RequireSize(3);
			pending_response_.push_back(read_microcontroller_address(uint16_t(next_command_[1] | (next_command_[2] << 8))));
		break;

		case 0x0d:	// Get version number.
			pending_response_.push_back(6);	// Seems to be what ROM03 is looking for?
		break;

		case 0x12:	// ???
			RequireSize(3);
		break;

		case 0x13: // ???
			RequireSize(3);
		break;

		// Enable device SRQ.
		case 0x50:	case 0x51:	case 0x52:	case 0x53:	case 0x54:	case 0x55:	case 0x56:	case 0x57:
		case 0x58:	case 0x59:	case 0x5a:	case 0x5b:	case 0x5c:	case 0x5d:	case 0x5e:	case 0x5f:
			set_device_srq(device_srq_ | (1 << (next_command_[1] & 0xf)));
		break;

		// Disable device SRQ.
		case 0x70:	case 0x71:	case 0x72:	case 0x73:	case 0x74:	case 0x75:	case 0x76:	case 0x77:
		case 0x78:	case 0x79:	case 0x7a:	case 0x7b:	case 0x7c:	case 0x7d:	case 0x7e:	case 0x7f:
			set_device_srq(device_srq_ & ~(1 << (next_command_[1] & 0xf)));
		break;

		// Transmit two bytes.
		case 0xb3:
			RequireSize(3);
		break;

		default:
			printf("TODO: ADB command %02x\n", next_command_[0]);
		break;
	}
#undef RequireSize

	printf("ADB executed: ");
	for(auto c : next_command_) printf("%02x ", c);
	printf("\n");

	// Input was dealt with, so throw it away.
	next_command_.clear();
}

void GLU::set_status(uint8_t status) {
	printf("TODO: set ADB status %02x\n", status);
}

// MARK: - Internal commands.

void GLU::set_modes(uint8_t modes) {
	modes_ = modes;	// TODO: and this has what effect?
}

void GLU::abort() {
}

void GLU::reset_microcontroller() {
}

void GLU::flush_keyboard_buffer() {
}

void GLU::set_configuration_bytes(uint8_t *) {
}

void GLU::set_device_srq(int mask) {
	// TODO: do I need to do any more than this here?
	device_srq_ = mask;
}

uint8_t GLU::read_microcontroller_address(uint16_t address) {
	printf("Read from microcontroller %04x\n", address);
	if(address == 0xe8)
		return 0x40;
	return 0;
}

void GLU::set_microcontroller_rom(const std::vector<uint8_t> &rom) {
	executor_.set_rom(rom);

	// TEST invocation.
	InstructionSet::Disassembler<InstructionSet::M50740::Parser, 0x1fff, InstructionSet::M50740::Instruction, uint8_t, uint16_t> disassembler;
	disassembler.disassemble(rom.data(), 0x1000, uint16_t(rom.size()), 0x1000);

	const auto instructions = disassembler.instructions();
	const auto entry_points = disassembler.entry_points();
	for(const auto &pair : instructions) {
		std::cout << std::hex << pair.first << "\t\t";
		if(entry_points.find(pair.first) != entry_points.end()) {
			std::cout << "L" << pair.first << "\t";
		} else {
			std::cout << "\t\t";
		}
		std::cout << operation_name(pair.second.operation) << " ";
		std::cout << address(pair.second.addressing_mode, &rom[pair.first - 0x1000], pair.first);

		std::cout << std::endl;
	}
}

void GLU::run_for(Cycles cycles) {
	executor_.run_for(cycles);
}

// MARK: - M50470 port handler

void GLU::set_port_output(int port, uint8_t value) {
	ports_[port] = value;
	switch(port) {
		case 0:
//			printf("Set R%d: %02x\n", register_address_, value);
			registers_[register_address_] = value;
		break;
		case 1:
//			printf("Keyboard write: %02x???\n", value);
		break;
		case 2:
//			printf("ADB data line input: %d???\n", value >> 7);
//			printf("IIe keyboard reset line: %d\n", (value >> 6)&1);
//			printf("IIgs reset line: %d\n", (value >> 5)&1);
//			printf("GLU strobe: %d\n", (value >> 4)&1);
//			printf("Select GLU register: %d [%02x]\n", value & 0xf, value);
			register_address_ = value & 0xf;
		break;
		case 3: {
//			printf("IIe KWS: %d\n", (value >> 6)&3);
//			printf("ADB data line output: %d\n", (value >> 3)&1);

			const bool new_adb_level = !(value & 0x08);
			if(new_adb_level != adb_level_) {
				if(!new_adb_level) {
					// Transition to low.
					constexpr float clock_rate = 894886.25;
					const float seconds = float(total_period_.as<int>()) / clock_rate;

					// Check for a valid bit length — 70 to 130 microseconds.
					// (Plus a little).
					if(seconds >= 0.000'56 && seconds <= 0.001'04) {
						printf("Attention\n");
					} else if(seconds >= 0.000'06 && seconds <= 0.000'14) {
						printf("bit: %d\n", (low_period_.as<int>() * 2) < total_period_.as<int>());
//						printf("tested: %0.2f\n", float(low_period_.as<int>()) / float(total_period_.as<int>()));
					} else {
						printf("Rejected %d microseconds\n", int(seconds * 1'000'000.0f));
					}

					total_period_ = low_period_ = Cycles(0);
				}
				adb_level_ = new_adb_level;
			}
		} break;

		default: assert(false);
	}
}

uint8_t GLU::get_port_input(int port) {
	switch(port) {
		case 0:
//			printf("Get R%d\n", register_address_);
		return registers_[register_address_];
		case 1:
//			printf("IIe keyboard read\n");
		return 0x06;
		case 2:
//			printf("ADB data line input, etc\n");
		return ports_[2];
		case 3:
//			printf("ADB data line output, etc\n");
		return ports_[3];

		default: assert(false);
	}
	return 0xff;
}

void GLU::run_ports_for(Cycles cycles) {
	total_period_ += cycles;
	if(!adb_level_) {
		low_period_ += cycles;
	}
}