package daemon

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"banger/internal/api"
	"banger/internal/model"
	"banger/internal/vmdns"
)

func (d *Daemon) CreateVM(ctx context.Context, params api.VMCreateParams) (vm model.VMRecord, err error) {
	d.mu.Lock()
	defer d.mu.Unlock()
	op := d.beginOperation("vm.create")
	defer func() {
		if err != nil {
			op.fail(err)
			return
		}
		op.done(vmLogAttrs(vm)...)
	}()
	if err := validateOptionalPositiveSetting("vcpu", params.VCPUCount); err != nil {
		return model.VMRecord{}, err
	}
	if err := validateOptionalPositiveSetting("memory", params.MemoryMiB); err != nil {
		return model.VMRecord{}, err
	}

	imageName := params.ImageName
	if imageName == "" {
		imageName = d.config.DefaultImageName
	}
	vmCreateStage(ctx, "resolve_image", "resolving image")
	image, err := d.FindImage(ctx, imageName)
	if err != nil {
		return model.VMRecord{}, err
	}
	vmCreateStage(ctx, "resolve_image", "using image "+image.Name)
	op.stage("image_resolved", imageLogAttrs(image)...)
	name := strings.TrimSpace(params.Name)
	if name == "" {
		name, err = d.generateName(ctx)
		if err != nil {
			return model.VMRecord{}, err
		}
	}
	if _, err := d.FindVM(ctx, name); err == nil {
		return model.VMRecord{}, fmt.Errorf("vm name already exists: %s", name)
	}
	id, err := model.NewID()
	if err != nil {
		return model.VMRecord{}, err
	}
	unlockVM := d.lockVMID(id)
	defer unlockVM()
	guestIP, err := d.store.NextGuestIP(ctx, bridgePrefix(d.config.BridgeIP))
	if err != nil {
		return model.VMRecord{}, err
	}
	vmDir := filepath.Join(d.layout.VMsDir, id)
	if err := os.MkdirAll(vmDir, 0o755); err != nil {
		return model.VMRecord{}, err
	}
	vsockCID, err := defaultVSockCID(guestIP)
	if err != nil {
		return model.VMRecord{}, err
	}
	systemOverlaySize := int64(model.DefaultSystemOverlaySize)
	if params.SystemOverlaySize != "" {
		systemOverlaySize, err = model.ParseSize(params.SystemOverlaySize)
		if err != nil {
			return model.VMRecord{}, err
		}
	}
	workDiskSize := int64(model.DefaultWorkDiskSize)
	if params.WorkDiskSize != "" {
		workDiskSize, err = model.ParseSize(params.WorkDiskSize)
		if err != nil {
			return model.VMRecord{}, err
		}
	}
	now := model.Now()
	spec := model.VMSpec{
		VCPUCount:             optionalIntOrDefault(params.VCPUCount, model.DefaultVCPUCount),
		MemoryMiB:             optionalIntOrDefault(params.MemoryMiB, model.DefaultMemoryMiB),
		SystemOverlaySizeByte: systemOverlaySize,
		WorkDiskSizeBytes:     workDiskSize,
		NATEnabled:            params.NATEnabled,
	}
	vm = model.VMRecord{
		ID:            id,
		Name:          name,
		ImageID:       image.ID,
		State:         model.VMStateCreated,
		CreatedAt:     now,
		UpdatedAt:     now,
		LastTouchedAt: now,
		Spec:          spec,
		Runtime: model.VMRuntime{
			State:         model.VMStateCreated,
			GuestIP:       guestIP,
			DNSName:       vmdns.RecordName(name),
			VMDir:         vmDir,
			VSockPath:     defaultVSockPath(d.layout.RuntimeDir, id),
			VSockCID:      vsockCID,
			SystemOverlay: filepath.Join(vmDir, "system.cow"),
			WorkDiskPath:  filepath.Join(vmDir, "root.ext4"),
			LogPath:       filepath.Join(vmDir, "firecracker.log"),
			MetricsPath:   filepath.Join(vmDir, "metrics.json"),
		},
	}
	vmCreateBindVM(ctx, vm)
	vmCreateStage(ctx, "reserve_vm", fmt.Sprintf("allocated %s (%s)", vm.Name, vm.Runtime.GuestIP))
	if err := d.store.UpsertVM(ctx, vm); err != nil {
		return model.VMRecord{}, err
	}
	op.stage("persisted", vmLogAttrs(vm)...)
	if params.NoStart {
		vm.State = model.VMStateStopped
		vm.Runtime.State = model.VMStateStopped
		if err := d.store.UpsertVM(ctx, vm); err != nil {
			return model.VMRecord{}, err
		}
		return vm, nil
	}
	return d.startVMLocked(ctx, vm, image)
}