// Package adapter maps each object kind to its PVE API endpoints and knows
// which fields are computed by PVE, which are specific to a cluster and how a
// canonical value is written back. Paths and schemas: see docs/api-pve.md.
package adapter

import (
	"context"
	"fmt"
	"net/url"
	"sort"
	"strings"

	"pve-confsync/internal/model"
	"pve-confsync/internal/pve"
)

// Policy of one field.
type Policy string

const (
	Sync     Policy = "sync"     // the reference value is copied to the clients
	Ignore   Policy = "ignore"   // never read nor written
	Override Policy = "override" // value comes from the client mapping only
)

// ReadMode chooses which SDN configuration is read: the applied one (reference)
// or the current one including pending changes (clients, which are written).
type ReadMode int

const (
	ReadCurrent ReadMode = iota
	ReadRunning
)

// Adapter handles one object kind.
type Adapter interface {
	Kind() model.Kind
	// SDN reports whether writes must go through the SDN lock and reload.
	SDN() bool
	// List reads and normalizes every object of this kind. known holds the objects
	// already read for previous kinds (subnets need the vnets).
	List(ctx context.Context, c *pve.Client, mode ReadMode, known []model.Object) ([]model.Object, []string, error)
	// DefaultPolicy is the built-in policy of a field when the configuration says nothing.
	DefaultPolicy(field string) Policy
	// Forbidden fields are never synchronized, whatever the configuration says.
	Forbidden(field string) bool
	// Required lists the fields an object must have to be created.
	Required(obj model.Object) []string
	// Immutable fields cannot be changed by an update (re-creation needed).
	Immutable(field string) bool
	// Canonicalize puts user supplied values (mapping, YAML) in the canonical form of List.
	Canonicalize(fields map[string]any)
	// Singleton kinds have exactly one object that is never created nor deleted.
	Singleton() bool
	Create(ctx context.Context, c *pve.Client, obj model.Object, lock string) error
	// Update changes fields of an existing object (target carries the id and current fields).
	Update(ctx context.Context, c *pve.Client, target model.Object, set map[string]any, unset []string, lock string) error
	Delete(ctx context.Context, c *pve.Client, obj model.Object, lock string) error
}

// All returns the adapters in dependency order.
func All() []Adapter {
	return []Adapter{datacenter{}, zone{}, vnet{}, subnet{}}
}

// ByKind returns the adapter of a kind.
func ByKind(k model.Kind) (Adapter, error) {
	for _, a := range All() {
		if a.Kind() == k {
			return a, nil
		}
	}
	return nil, fmt.Errorf("unknown kind %q", k)
}

// canon converts one decoded API value into its canonical form:
// objects become property strings with sorted keys, lists sorted []string.
func canon(v any) any {
	switch t := v.(type) {
	case map[string]any:
		return propertyString(t)
	case []any:
		l := make([]string, 0, len(t))
		for _, e := range t {
			if m, ok := e.(map[string]any); ok {
				l = append(l, propertyString(m))
			} else {
				l = append(l, pve.Str(e))
			}
		}
		sort.Strings(l)
		return l
	default:
		return pve.Str(v)
	}
}

// propertyString prints a PVE property string ("k1=v1,k2=v2"), keys sorted.
// PVE parses property strings independently of the key order.
func propertyString(m map[string]any) string {
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	parts := make([]string, 0, len(keys))
	for _, k := range keys {
		v := m[k]
		if l, ok := v.([]any); ok {
			s := make([]string, 0, len(l))
			for _, e := range l {
				s = append(s, pve.Str(e))
			}
			sort.Strings(s)
			parts = append(parts, k+"="+strings.Join(s, ";"))
			continue
		}
		parts = append(parts, k+"="+pve.Str(v))
	}
	return strings.Join(parts, ",")
}

// normalizeAPI builds the canonical field map of an API object, without the given keys.
func normalizeAPI(raw map[string]any, drop ...string) map[string]any {
	skip := map[string]bool{"digest": true, "state": true, "pending": true}
	for _, d := range drop {
		skip[d] = true
	}
	out := map[string]any{}
	for k, v := range raw {
		if skip[k] || v == nil {
			continue
		}
		out[k] = canon(v)
	}
	return out
}

// form encodes canonical values for a write: lists become repeated parameters.
func form(set map[string]any, unset []string, lock string) url.Values {
	f := url.Values{}
	for k, v := range set {
		switch t := v.(type) {
		case []string:
			for _, e := range t {
				f.Add(k, e)
			}
		default:
			f.Set(k, fmt.Sprint(t))
		}
	}
	if len(unset) > 0 {
		u := append([]string(nil), unset...)
		sort.Strings(u)
		f.Set("delete", strings.Join(u, ","))
	}
	if lock != "" {
		f.Set("lock-token", lock)
	}
	return f
}

func modeQuery(mode ReadMode) url.Values {
	if mode == ReadRunning {
		return url.Values{"running": {"1"}}
	}
	return nil
}