package disk

import (
	"math/rand"

	"github.com/osbuild/osbuild-composer/internal/blueprint"
)

const (
	BIOSBootPartitionGUID = "21686148-6449-6E6F-744E-656564454649"
	BIOSBootPartitionUUID = "FAC7F1FB-3E8D-4137-A512-961DE09A5549"

	FilesystemDataGUID = "0FC63DAF-8483-4772-8E79-3D69D8477DE4"
	FilesystemDataUUID = "CB07C243-BC44-4717-853E-28852021225B"

	EFISystemPartitionGUID = "C12A7328-F81F-11D2-BA4B-00A0C93EC93B"
	EFISystemPartitionUUID = "68B2905B-DF3E-4FB3-80FA-49D1E773AA33"
	EFIFilesystemUUID      = "7B77-95E7"

	RootPartitionUUID = "6264D520-3FB9-423F-8AB8-7A0A8E3D3562"
)

func CreatePartitionTable(
	mountpoints []blueprint.FilesystemCustomization,
	imageSize uint64,
	basePartitionTable *PartitionTable,
	rng *rand.Rand,
) (PartitionTable, error) {

	// we are modifying the contents of the base partition table,
	// including the file systems, which are shared among shallow
	// copies of the partition table, so make a copy first
	table, cloneOk := basePartitionTable.Clone().(*PartitionTable)
	if !cloneOk {
		panic("PartitionTable.Clone() returned an Entity that cannot be converted to *PartitionTable; this is a programming error")
	}

	for _, m := range mountpoints {
		// if we already have a partition ensure that the
		// size is at least the requested size, otherwise
		// create a new filesystem with that size
		part := table.FindPartitionForMountpoint(m.Mountpoint)
		if part != nil {
			part.EnsureSize(m.MinSize)
		} else {
			err := table.CreateFilesystem(m.Mountpoint, m.MinSize)
			if err != nil {
				return PartitionTable{}, err
			}
		}
	}

	// Calculate partition table offsets and sizes
	table.updatePartitionStartPointOffsets(imageSize)

	// Generate new UUIDs for filesystems and partitions
	table.GenerateUUIDs(rng)

	return *table, nil
}