package proxmox

import (
	"context"
	"fmt"
	"time"

	"github.com/go-logr/logr"
)

// Delete is spec entry 11: under the per-name lock, stop and destroy the VM
// when it is ours, then delete its seed. Everything already gone is
// success, and nothing of ours is left when nil is returned, so Get
// afterwards is NotFound.
func (p *Provider) Delete(ctx context.Context, id string) error {
	vmid, name, err := parseProviderID(id)
	if err != nil {
		return p.wrapErr("delete", id, err)
	}
	log := p.logger(ctx).WithValues("vmid", vmid, "name", name)
	unlock, err := p.lockName(ctx, name)
	if err != nil {
		return p.wrapErr("delete", id, err)
	}
	defer unlock()

	node, err := p.destroy(ctx, log, vmid, name)
	if err != nil {
		return p.wrapErr("delete", id, err)
	}
	if node == "" {
		err = p.deleteSeedEverywhere(ctx, log, name)
	} else {
		log = log.WithValues("node", node)
		err = p.deleteSeed(ctx, log, node, name)
	}
	if err != nil {
		return p.wrapErr("delete", id, err)
	}
	log.V(1).Info("proxmox vm deleted", "destroyed", node != "")
	return nil
}

// destroy is steps 2 to 6. It returns the node of the VM it destroyed, or
// "" when there was no VM of ours to destroy: then the seed's node is not
// known, and the seed is looked for on every node.
func (p *Provider) destroy(ctx context.Context, log logr.Logger, vmid int, name string) (string, error) {
	r, ok, err := p.resolve(ctx, vmid)
	if err != nil {
		return "", err
	}
	if !ok {
		log.V(1).Info("proxmox vm already gone")
		return "", nil
	}
	log = log.WithValues("node", r.Node)
	if r.Lock != "" && r.Lock != lockSuspended {
		return "", transientf("VM %d is locked (%s)", vmid, r.Lock)
	}
	if r.Status == "unknown" {
		return "", transientf("VM %d has status unknown: its node %s is not answering", vmid, r.Node)
	}
	cfg, err := p.api.VMConfig(ctx, r.Node, vmid)
	if isNotExist(err) {
		log.V(1).Info("proxmox vm already gone")
		return "", nil
	}
	if err != nil {
		return "", fmt.Errorf("reading config of VM %d: %w", vmid, err)
	}
	if cfg["name"] != name {
		log.V(1).Info("proxmox vm at this vmid is not ours, left alone", "vmName", cfg["name"])
		return "", nil
	}
	if !parseDescription(cfg["description"]).Managed {
		log.V(1).Info("proxmox vm carries no proxy-operator mark, left alone")
		return "", nil
	}
	switch lock := cfg["lock"]; lock {
	case "":
	case lockSuspended:
		// Destroy refuses a locked VM and the lock never clears on its own,
		// so only an admin can move this on, as in Create's ownership check.
		return "", permanentf("VM %d named %s is hibernated (lock suspended); resume or destroy it in Proxmox", vmid, name)
	default:
		return "", transientf("VM %d is locked (%s)", vmid, lock)
	}

	// The listing shows a paused VM as running, and Stop ends it too.
	if r.Status != "stopped" {
		gone, err := p.runTask(ctx, log, "stopping", vmid, p.budgets.stop, func() (string, error) { return p.api.Stop(ctx, r.Node, vmid) })
		if err != nil || gone {
			return r.Node, err
		}
	}
	if _, err := p.runTask(ctx, log, "destroying", vmid, p.budgets.destroy, func() (string, error) { return p.api.Destroy(ctx, r.Node, vmid) }); err != nil {
		return "", err
	}
	return r.Node, nil
}

// runTask submits a task on a VM and waits for it. A VM that is gone by the
// time the task is submitted reports gone: it is what the task was for.
func (p *Provider) runTask(ctx context.Context, log logr.Logger, what string, vmid int, budget time.Duration, submit func() (string, error)) (bool, error) {
	upid, err := submit()
	if isNotExist(err) {
		log.V(1).Info("proxmox vm already gone")
		return true, nil
	}
	if err != nil {
		return false, fmt.Errorf("%s VM %d: %w", what, vmid, err)
	}
	if err := p.waitTask(ctx, log, upid, budget); err != nil {
		return false, fmt.Errorf("%s VM %d: %w", what, vmid, err)
	}
	return false, nil
}

// deleteSeed is step 7 on one node. A missing volume still ends in a
// successful task (F13), so nothing is matched.
func (p *Provider) deleteSeed(ctx context.Context, log logr.Logger, node, name string) error {
	volid := seedVolID(p.cfg.ISOStorage, name)
	upid, err := p.api.DeleteVolume(ctx, node, p.cfg.ISOStorage, volid)
	if err != nil {
		return fmt.Errorf("deleting seed %s on %s: %w", volid, node, err)
	}
	if err := p.waitTask(ctx, log, upid, p.budgets.seedDelete); err != nil {
		return fmt.Errorf("deleting seed %s on %s: %w", volid, node, err)
	}
	return nil
}

// deleteSeedEverywhere is step 7 when the VM's node is not known: every
// configured node is tried, and one that fails is logged and skipped, so a
// node that is down or lacks the storage cannot hold the Delete up. An
// ended ctx fails the call instead.
func (p *Provider) deleteSeedEverywhere(ctx context.Context, log logr.Logger, name string) error {
	for _, node := range p.cfg.Nodes {
		err := p.deleteSeed(ctx, log, node, name)
		if err == nil {
			continue
		}
		if ctx.Err() != nil {
			return err
		}
		log.V(1).Info("proxmox seed delete failed on a node, skipped", "node", node, "reason", err.Error())
	}
	return nil
}