package kubeedit

import (
	"context"
	"fmt"
	"sort"

	"git.k8s-git-k6n.net/mats/fancy-dns/internal/config"
	"git.k8s-git-k6n.net/mats/fancy-dns/internal/kubesource"
)

// GroupObject is a stored ClientGroup.
type GroupObject struct {
	Name string
	Spec kubesource.ClientGroupSpec
}

// Groups lists the ClientGroup objects in evaluation order.
func (e *Editor) Groups(ctx context.Context) ([]GroupObject, error) {
	items, err := e.list(ctx, kubesource.GroupGVR)
	if err != nil {
		return nil, err
	}
	out := make([]GroupObject, 0, len(items))
	for i := range items {
		var s kubesource.ClientGroupSpec
		if err := decodeSpec(&items[i], &s); err != nil {
			continue // the runtime reports an undecodable object; the console skips it
		}
		out = append(out, GroupObject{Name: items[i].GetName(), Spec: s})
	}
	sort.SliceStable(out, func(i, j int) bool {
		if out[i].Spec.Priority != out[j].Spec.Priority {
			return out[i].Spec.Priority < out[j].Spec.Priority
		}
		return out[i].Name < out[j].Name
	})
	return out, nil
}

// SpecFromGroup converts the console's group to an object spec.
func SpecFromGroup(g config.Group, priority int32) kubesource.ClientGroupSpec {
	return kubesource.ClientGroupSpec{
		Priority:      priority,
		Comment:       g.Comment,
		Match:         g.Match,
		Policy:        g.Policy,
		AllowDomains:  g.AllowDomains,
		DenyDomains:   g.DenyDomains,
		SkipBlocklist: g.SkipBlocklist,
		SkipCache:     g.SkipCache,
		RateLimit:     g.RateLimit,
		MaxConcurrent: g.MaxConcurrent,
		LogQueries:    g.LogQueries,
		Upstreams:     g.Upstreams,
	}
}

// SyncResult says what SyncGroups changed.
type SyncResult struct {
	Created, Updated, Deleted []string
}

// SyncGroups makes the stored ClientGroups match the console's list.
//
// desired is the full list the console sent, in the order the operator put it.
// Groups for which foreign returns true belong to something else (the runtime's
// YAML) and are neither written nor deleted. Every group is validated before
// anything is written, so a bad group changes nothing. Priorities follow the
// list position, so reordering in the console reorders evaluation.
func (e *Editor) SyncGroups(ctx context.Context, desired []config.Group, foreign func(string) bool, actor string) (SyncResult, error) {
	var res SyncResult
	existing, err := e.Groups(ctx)
	if err != nil {
		return res, err
	}
	have := make(map[string]GroupObject, len(existing))
	for _, g := range existing {
		have[g.Name] = g
	}

	type write struct {
		name string
		spec kubesource.ClientGroupSpec
		new  bool
	}
	var writes []write
	keep := map[string]bool{}
	for i, g := range desired {
		if foreign != nil && foreign(g.Name) {
			if _, ours := have[g.Name]; !ours {
				continue
			}
		}
		if err := checkName("group", g.Name); err != nil {
			return res, err
		}
		spec := SpecFromGroup(g, int32(i+1)*10)
		if _, err := kubesource.CheckGroup(g.Name, spec); err != nil {
			return res, fmt.Errorf("group %q: %w", g.Name, err)
		}
		keep[g.Name] = true
		cur, ok := have[g.Name]
		switch {
		case !ok:
			writes = append(writes, write{g.Name, spec, true})
		case !sameSpec(cur.Spec, spec):
			writes = append(writes, write{g.Name, spec, false})
		}
	}
	for _, w := range writes {
		if _, err := e.upsert(ctx, kubesource.GroupGVR, "ClientGroup", w.name, actor, w.spec); err != nil {
			return res, fmt.Errorf("write group %q: %w", w.name, err)
		}
		if w.new {
			res.Created = append(res.Created, w.name)
		} else {
			res.Updated = append(res.Updated, w.name)
		}
	}
	for _, g := range existing {
		if keep[g.Name] {
			continue
		}
		if err := e.remove(ctx, kubesource.GroupGVR, g.Name); err != nil {
			return res, err
		}
		res.Deleted = append(res.Deleted, g.Name)
	}
	return res, nil
}