package proxmox

import (
	"context"
	"strings"

	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
)

// proxyTag is the tag Create sets for the Proxmox UI; ListByTag uses it,
// with the name prefix provider.NameFromUID gives, only to pick candidates.
// The mark decides.
const (
	proxyTag        = "proxy_operator"
	proxyNamePrefix = "proxy-"
)

// ListByTag is spec entry 12: one resources call covers every node, then
// one config read per candidate for the mark. GC reads only ID, UID and
// CreatedAt (contract §2.4), so no status or agent call is made. The
// resources call failing fails the list; one unreadable candidate is
// skipped, unless ctx ended, which fails the list rather than pass off a
// partial view as complete.
func (p *Provider) ListByTag(ctx context.Context) ([]provider.Instance, error) {
	log := p.logger(ctx)
	rs, err := p.api.ClusterResources(ctx)
	if err != nil {
		return nil, p.wrapErr("list", "", err)
	}
	var (
		out                 []provider.Instance
		candidates, skipped int
	)
	for _, r := range rs {
		if !isCandidate(r) {
			continue
		}
		candidates++
		vlog := log.WithValues("vmid", r.VMID, "name", r.Name, "node", r.Node)
		cfg, err := p.api.VMConfig(ctx, r.Node, r.VMID)
		if err != nil {
			if ctx.Err() != nil {
				return nil, p.wrapErr("list", "", err)
			}
			skipped++
			vlog.V(1).Info("skipping unreadable proxmox vm", "error", err.Error())
			continue
		}
		mark := parseDescription(cfg["description"])
		if !mark.Managed {
			continue
		}
		inst := provider.Instance{ID: formatProviderID(r.VMID, r.Name), UID: mark.UID, CreatedAt: mark.CreatedAt}
		vlog.V(2).Info("proxmox listed instance", "id", inst.ID, "uid", inst.UID, "createdAt", inst.CreatedAt)
		out = append(out, inst)
	}
	log.V(1).Info("proxmox vms listed", "vms", len(rs), "candidates", candidates, "managed", len(out), "skipped", skipped)
	return out, nil
}

// isCandidate picks the resource entries worth a config read: QEMU VMs, not
// templates, named, and either tagged or named like a proxy. A nameless
// entry is a clone in progress, whose Create is still running.
func isCandidate(r vmResource) bool {
	if r.Type != "qemu" || r.Template != 0 || r.Name == "" {
		return false
	}
	return strings.HasPrefix(r.Name, proxyNamePrefix) || hasTag(r.Tags, proxyTag)
}

// hasTag reports whether tags, as Proxmox lists them (";"-separated, though
// "," and spaces are accepted on input), contains tag. Proxmox folds tags to
// lower case.
func hasTag(tags, tag string) bool {
	for _, t := range strings.FieldsFunc(tags, func(r rune) bool { return r == ';' || r == ',' || r == ' ' }) {
		if strings.EqualFold(t, tag) {
			return true
		}
	}
	return false
}