package daemon

import (
	"context"
	"errors"

	"banger/internal/api"
	"banger/internal/model"
	"banger/internal/system"
)

func (d *Daemon) SetVM(ctx context.Context, params api.VMSetParams) (model.VMRecord, error) {
	return d.withVMLockByRef(ctx, params.IDOrName, func(vm model.VMRecord) (model.VMRecord, error) {
		return d.setVMLocked(ctx, vm, params)
	})
}

func (d *Daemon) setVMLocked(ctx context.Context, current model.VMRecord, params api.VMSetParams) (vm model.VMRecord, err error) {
	vm = current
	op := d.beginOperation("vm.set", "vm_ref", vm.ID)
	defer func() {
		if err != nil {
			op.fail(err, vmLogAttrs(vm)...)
			return
		}
		op.done(vmLogAttrs(vm)...)
	}()
	running := d.vmAlive(vm)
	if params.VCPUCount != nil {
		if err := validateOptionalPositiveSetting("vcpu", params.VCPUCount); err != nil {
			return model.VMRecord{}, err
		}
		if running {
			return model.VMRecord{}, errors.New("vcpu changes require the VM to be stopped")
		}
		op.stage("update_vcpu", "vcpu_count", *params.VCPUCount)
		vm.Spec.VCPUCount = *params.VCPUCount
	}
	if params.MemoryMiB != nil {
		if err := validateOptionalPositiveSetting("memory", params.MemoryMiB); err != nil {
			return model.VMRecord{}, err
		}
		if running {
			return model.VMRecord{}, errors.New("memory changes require the VM to be stopped")
		}
		op.stage("update_memory", "memory_mib", *params.MemoryMiB)
		vm.Spec.MemoryMiB = *params.MemoryMiB
	}
	if params.WorkDiskSize != "" {
		size, err := model.ParseSize(params.WorkDiskSize)
		if err != nil {
			return model.VMRecord{}, err
		}
		if running {
			return model.VMRecord{}, errors.New("disk changes require the VM to be stopped")
		}
		if size < vm.Spec.WorkDiskSizeBytes {
			return model.VMRecord{}, errors.New("disk size can only grow")
		}
		if size > vm.Spec.WorkDiskSizeBytes {
			if exists(vm.Runtime.WorkDiskPath) {
				op.stage("resize_work_disk", "from_bytes", vm.Spec.WorkDiskSizeBytes, "to_bytes", size)
				if err := d.validateWorkDiskResizePrereqs(); err != nil {
					return model.VMRecord{}, err
				}
				if err := system.ResizeExt4Image(ctx, d.runner, vm.Runtime.WorkDiskPath, size); err != nil {
					return model.VMRecord{}, err
				}
			}
			vm.Spec.WorkDiskSizeBytes = size
		}
	}
	if params.NATEnabled != nil {
		op.stage("update_nat", "nat_enabled", *params.NATEnabled)
		vm.Spec.NATEnabled = *params.NATEnabled
	}
	if running {
		if err := d.applyCapabilityConfigChanges(ctx, current, vm); err != nil {
			return model.VMRecord{}, err
		}
	}
	system.TouchNow(&vm)
	if err := d.store.UpsertVM(ctx, vm); err != nil {
		return model.VMRecord{}, err
	}
	return vm, nil
}