//
//  FAT12.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 07/01/2018.
//  Copyright 2018 Thomas Harte. All rights reserved.
//

#include "PCBooter.hpp"

#include "Utility/ImplicitSectors.hpp"

using namespace Storage::Disk;

PCBooter::PCBooter(const std::string &file_name) :
	MFMSectorDump(file_name) {
	// The only sanity check here is whether a sensible
	// geometry is encoded in the first sector, or can be guessed.
	const auto file_size = file_.stats().st_size;

	// Check that file size is one of the accepted options.
	switch(file_size) {
		default: throw Error::InvalidFormat;

		case 512 * 8 * 40:
			head_count_ = 1;
			track_count_ = 40;
			sector_count_ = 8;
		break;

		case 512 * 8 * 40 * 2:
			head_count_ = 2;
			track_count_ = 40;
			sector_count_ = 8;
		break;

		case 512 * 9 * 40:
			head_count_ = 1;
			track_count_ = 40;
			sector_count_ = 9;
		break;

		case 512 * 9 * 40 * 2:
			head_count_ = 2;
			track_count_ = 40;
			sector_count_ = 9;
		break;
	}

	// TODO: probably single density, actually?
	set_geometry(sector_count_, 2, 1, Encodings::MFM::Density::Double);

	// TODO: check that an appropriate INT or similar is in the boot sector?
	// Should probably factor out the "does this look like a PC boot sector?" test,
	// as it can also be used to disambiguate FAT12 disks.
}

HeadPosition PCBooter::get_maximum_head_position() {
	return HeadPosition(track_count_);
}

int PCBooter::get_head_count() {
	return head_count_;
}

long PCBooter::get_file_offset_for_position(Track::Address address) {
	return (address.position.as_int() * head_count_ + address.head) * 512 * sector_count_;
}