//
//  Archimedes.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 04/03/2024.
//  Copyright © 2024 Thomas Harte. All rights reserved.
//

#include "Archimedes.hpp"

#include "../../AudioProducer.hpp"
#include "../../KeyboardMachine.hpp"
#include "../../MediaTarget.hpp"
#include "../../ScanProducer.hpp"
#include "../../TimedMachine.hpp"

#include "../../../InstructionSets/ARM/Executor.hpp"

#include <algorithm>
#include <array>
#include <vector>

namespace Archimedes {

struct Memory {
	void set_rom(const std::vector<uint8_t> &rom) {
		std::copy(
			rom.begin(),
			rom.begin() + static_cast<ptrdiff_t>(std::min(rom.size(), rom_.size())),
			rom_.begin());
	}

	template <typename IntT>
	bool write(uint32_t address, IntT source, InstructionSet::ARM::Mode mode, bool trans) {
		(void)mode;
		(void)trans;

		printf("W of %08x to %08x [%lu]\n", source, address, sizeof(IntT));

		if(has_moved_rom_ && address < ram_.size()) {
			*reinterpret_cast<IntT *>(&ram_[address]) = source;
		}

		return true;
	}

	template <typename IntT>
	bool read(uint32_t address, IntT &source, InstructionSet::ARM::Mode mode, bool trans) {
		(void)mode;
		(void)trans;

		if(address >= 0x3800000) {
			has_moved_rom_ = true;
			source = *reinterpret_cast<const IntT *>(&rom_[address - 0x3800000]);
		} else if(!has_moved_rom_) {
			// TODO: this is true only very transiently.
			source = *reinterpret_cast<const IntT *>(&rom_[address]);
		} else if(address < ram_.size()) {
			source = *reinterpret_cast<const IntT *>(&ram_[address]);
		} else {
			source = 0;
		}

		return true;
	}

	private:
		bool has_moved_rom_ = false;
		std::array<uint8_t, 4*1024*1024> ram_{};
		std::array<uint8_t, 2*1024*1024> rom_;
};

class ConcreteMachine:
	public Machine,
	public MachineTypes::MediaTarget,
	public MachineTypes::TimedMachine,
	public MachineTypes::ScanProducer
{
	public:
		ConcreteMachine(
			const Analyser::Static::Target &target,
			const ROMMachine::ROMFetcher &rom_fetcher
		) {
			constexpr ROM::Name risc_os = ROM::Name::AcornRISCOS319;
			ROM::Request request(risc_os);
			auto roms = rom_fetcher(request);
			if(!request.validate(roms)) {
				throw ROMMachine::Error::MissingROMs;
			}

			executor_.bus.set_rom(roms.find(risc_os)->second);

			// TODO: pick a sensible clock rate; this is just code for '20 MIPS, please'.
			set_clock_rate(20'000'000);

			insert_media(target.media);
		}

	private:

		// MARK: - ScanProducer.
		void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
			(void)scan_target;
		}
		Outputs::Display::ScanStatus get_scaled_scan_status() const override {
			return Outputs::Display::ScanStatus();
		}

		// MARK: - TimedMachine.
		void run_for(Cycles cycles) override {
			auto instructions = cycles.as<int>();
			while(instructions--) {
				uint32_t instruction;
				executor_.bus.read(executor_.pc(), instruction, executor_.registers().mode(), false);
				// TODO: what if abort? How about pipeline prefetch?

				InstructionSet::ARM::execute<arm_model>(instruction, executor_);
			}
		}

		// MARK: - MediaTarget
		bool insert_media(const Analyser::Static::Media &) override {
//			int c = 0;
//			for(auto &disk : media.disks) {
//				fdc_.set_disk(disk, c);
//				c++;
//				if(c == 4) break;
//			}
//			return true;
			return false;
		}

		// MARK: - ARM execution
		static constexpr auto arm_model = InstructionSet::ARM::Model::ARMv2;
		InstructionSet::ARM::Executor<arm_model, Memory> executor_;
};

}

using namespace Archimedes;

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