// Package pvetest is an in-memory fake of the subset of the PVE 9.x API used by
// pve-confsync, for tests. It mimics the behaviours that matter for the engine:
// parsed datacenter options on GET, property strings on PUT, SDN pending/running
// configurations, global SDN lock with token, rollback and reload task.
package pvetest

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"net/url"
	"sort"
	"strings"
	"sync"
)

// SDN holds one SDN configuration (pending or running).
type SDN struct {
	Zones   map[string]map[string]any
	VNets   map[string]map[string]any
	Subnets map[string]map[string]any // id "zone-ip-mask" -> fields (with vnet)
}

func newSDN() SDN {
	return SDN{map[string]map[string]any{}, map[string]map[string]any{}, map[string]map[string]any{}}
}

func (s SDN) clone() SDN {
	c := newSDN()
	cp := func(dst, src map[string]map[string]any) {
		for k, v := range src {
			m := map[string]any{}
			for f, x := range v {
				m[f] = x
			}
			dst[k] = m
		}
	}
	cp(c.Zones, s.Zones)
	cp(c.VNets, s.VNets)
	cp(c.Subnets, s.Subnets)
	return c
}

// Server is a fake PVE cluster.
type Server struct {
	*httptest.Server
	mu      sync.Mutex
	Version string            // pve-manager version, e.g. 9.1.4
	Options map[string]string // datacenter.cfg as written (property strings)
	Pending SDN
	Running SDN
	Lock    string
	Perms   map[string]map[string]any
	FailOn  string   // "METHOD path" answering 500, to test rollbacks
	Calls   []string // "METHOD path" of every write
	locks   int
}

// New starts a fake cluster.
func New(version string) *Server {
	s := &Server{Version: version, Options: map[string]string{}, Pending: newSDN(), Running: newSDN(),
		Perms: map[string]map[string]any{}}
	s.Server = httptest.NewTLSServer(http.HandlerFunc(s.handle))
	return s
}

// Commit makes the pending SDN configuration the running one (like an apply).
func (s *Server) Commit() {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.Running = s.Pending.clone()
}

func reply(w http.ResponseWriter, data any) {
	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(map[string]any{"data": data})
}

func fail(w http.ResponseWriter, code int, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	_ = json.NewEncoder(w).Encode(map[string]any{"data": nil, "message": msg})
}

func (s *Server) handle(w http.ResponseWriter, r *http.Request) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if !strings.HasPrefix(r.Header.Get("Authorization"), "PVEAPIToken=") {
		fail(w, 401, "no ticket")
		return
	}
	_ = r.ParseForm()
	p := strings.TrimPrefix(r.URL.Path, "/api2/json/")
	seg := strings.Split(p, "/")
	key := r.Method + " " + p
	if r.Method != http.MethodGet {
		s.Calls = append(s.Calls, key)
	}
	if s.FailOn != "" && s.FailOn == key {
		fail(w, 500, "injected failure")
		return
	}
	// writes on SDN objects must carry the token while the lock is held
	if r.Method != http.MethodGet && strings.HasPrefix(p, "cluster/sdn/") && p != "cluster/sdn/lock" && p != "cluster/sdn/rollback" {
		if s.Lock != "" && r.Form.Get("lock-token") != s.Lock {
			fail(w, 500, "SDN config is locked")
			return
		}
	}
	running := r.Form.Get("running") == "1"
	cfg := &s.Pending
	if running {
		cfg = &s.Running
	}
	switch {
	case key == "GET version" || (r.Method == "GET" && len(seg) == 3 && seg[0] == "nodes" && seg[2] == "version"):
		reply(w, map[string]any{"version": s.Version, "release": release(s.Version), "repoid": "abcdef"})
	case key == "GET cluster/status":
		reply(w, []any{
			map[string]any{"type": "cluster", "name": "fake", "quorate": 1},
			map[string]any{"type": "node", "name": "n1", "online": 1},
		})
	case r.Method == "GET" && len(seg) == 4 && seg[0] == "nodes" && seg[2] == "sdn" && seg[3] == "zones":
		var out []any
		for id := range s.Running.Zones {
			out = append(out, map[string]any{"zone": id, "status": "available"})
		}
		reply(w, out)
	case r.Method == "GET" && len(seg) == 5 && seg[0] == "nodes" && seg[2] == "tasks" && seg[4] == "status":
		reply(w, map[string]any{"status": "stopped", "exitstatus": "OK"})
	case key == "GET access/permissions":
		reply(w, s.Perms)
	case key == "GET cluster/options":
		reply(w, s.parsedOptions())
	case key == "PUT cluster/options":
		for k, v := range r.PostForm {
			if k == "delete" {
				for _, d := range strings.Split(v[0], ",") {
					delete(s.Options, d)
				}
				continue
			}
			s.Options[k] = v[0]
		}
		reply(w, nil)
	case key == "POST cluster/sdn/lock":
		if r.Form.Get("allow-pending") != "1" && s.hasPending() {
			fail(w, 500, "configuration has pending changes")
			return
		}
		if s.Lock != "" {
			fail(w, 500, "could not acquire lock for SDN config")
			return
		}
		s.locks++
		s.Lock = fmt.Sprintf("token-%d", s.locks)
		reply(w, s.Lock)
	case key == "POST cluster/sdn/rollback":
		if r.Form.Get("lock-token") != s.Lock {
			fail(w, 500, "bad token")
			return
		}
		s.Pending = s.Running.clone()
		if r.Form.Get("release-lock") != "0" {
			s.Lock = ""
		}
		reply(w, nil)
	case key == "PUT cluster/sdn":
		s.Running = s.Pending.clone()
		if r.Form.Get("release-lock") != "0" {
			s.Lock = ""
		}
		reply(w, "UPID:n1:00001234:00005678:65000000:reloadnetworkall::root@pam!confsync:")
	case p == "cluster/sdn/zones" && r.Method == "GET":
		reply(w, list(cfg.Zones, "zone"))
	case p == "cluster/sdn/zones" && r.Method == "POST":
		create(w, r, cfg.Zones, "zone", "lock-token")
	case len(seg) == 4 && seg[2] == "zones":
		item(w, r, cfg.Zones, seg[3])
	case p == "cluster/sdn/vnets" && r.Method == "GET":
		reply(w, list(cfg.VNets, "vnet"))
	case p == "cluster/sdn/vnets" && r.Method == "POST":
		if z := r.PostForm.Get("zone"); s.Pending.Zones[z] == nil {
			fail(w, 400, "zone "+z+" does not exist")
			return
		}
		create(w, r, cfg.VNets, "vnet", "lock-token")
	case len(seg) == 4 && seg[2] == "vnets":
		item(w, r, cfg.VNets, seg[3])
	case len(seg) == 5 && seg[2] == "vnets" && seg[4] == "subnets" && r.Method == "GET":
		m := map[string]map[string]any{}
		for id, f := range cfg.Subnets {
			if f["vnet"] == seg[3] {
				m[id] = f
			}
		}
		reply(w, list(m, "subnet"))
	case len(seg) == 5 && seg[2] == "vnets" && seg[4] == "subnets" && r.Method == "POST":
		v := s.Pending.VNets[seg[3]]
		if v == nil {
			fail(w, 400, "vnet does not exist")
			return
		}
		cidr := r.PostForm.Get("subnet")
		id := fmt.Sprint(v["zone"]) + "-" + strings.Replace(cidr, "/", "-", 1)
		if s.Pending.Subnets[id] != nil {
			fail(w, 400, "already defined")
			return
		}
		f := fields(r.PostForm, "subnet", "type", "lock-token")
		f["vnet"] = seg[3]
		s.Pending.Subnets[id] = f
		reply(w, nil)
	case len(seg) == 6 && seg[2] == "vnets" && seg[4] == "subnets":
		item(w, r, cfg.Subnets, seg[5])
	default:
		fail(w, 501, "not implemented in fake: "+key)
	}
}

func release(v string) string {
	p := strings.SplitN(v, ".", 3)
	if len(p) < 2 {
		return v
	}
	return p[0] + "." + p[1]
}

func (s *Server) hasPending() bool {
	a, _ := json.Marshal(s.Pending)
	b, _ := json.Marshal(s.Running)
	return string(a) != string(b)
}

// parsedOptions mimics parse_datacenter_config: some options come back as objects/lists.
func (s *Server) parsedOptions() map[string]any {
	out := map[string]any{"description": "", "mac_prefix": "BC:24:11", "allowed-tags": []string{}}
	for k, v := range s.Options {
		switch k {
		case "registered-tags":
			out[k] = strings.Split(v, ";")
		case "tag-style", "next-id", "user-tag-access", "migration", "ha", "crs":
			m := map[string]any{}
			for _, kv := range strings.Split(v, ",") {
				p := strings.SplitN(kv, "=", 2)
				if len(p) != 2 {
					continue
				}
				if k == "user-tag-access" && p[0] == "user-allow-list" {
					m[p[0]] = strings.Split(p[1], ";")
					continue
				}
				if k == "next-id" {
					var n json.Number = json.Number(p[1])
					m[p[0]] = n
					continue
				}
				m[p[0]] = p[1]
			}
			out[k] = m
		default:
			out[k] = v
		}
	}
	return out
}

func list(m map[string]map[string]any, idKey string) []any {
	ids := make([]string, 0, len(m))
	for id := range m {
		ids = append(ids, id)
	}
	sort.Strings(ids)
	out := []any{}
	for _, id := range ids {
		o := map[string]any{idKey: id, "digest": "0123"}
		for k, v := range m[id] {
			o[k] = v
		}
		out = append(out, o)
	}
	return out
}

func fields(f url.Values, skip ...string) map[string]any {
	out := map[string]any{}
	sk := map[string]bool{}
	for _, s := range skip {
		sk[s] = true
	}
	for k, v := range f {
		if sk[k] {
			continue
		}
		if len(v) > 1 || k == "dhcp-range" { // array in the PVE schema
			l := make([]any, len(v))
			for i := range v {
				l[i] = v[i]
			}
			out[k] = l
		} else {
			out[k] = v[0]
		}
	}
	return out
}

func create(w http.ResponseWriter, r *http.Request, m map[string]map[string]any, idKey string, skip ...string) {
	id := r.PostForm.Get(idKey)
	if m[id] != nil {
		fail(w, 400, idKey+" "+id+" already defined")
		return
	}
	m[id] = fields(r.PostForm, append(skip, idKey)...)
	reply(w, nil)
}

func item(w http.ResponseWriter, r *http.Request, m map[string]map[string]any, id string) {
	o := m[id]
	if o == nil {
		fail(w, 404, id+" does not exist")
		return
	}
	switch r.Method {
	case http.MethodPut:
		for k, v := range fields(r.PostForm, "lock-token", "delete", "digest") {
			o[k] = v
		}
		if d := r.PostForm.Get("delete"); d != "" {
			for _, k := range strings.Split(d, ",") {
				delete(o, k)
			}
		}
		reply(w, nil)
	case http.MethodDelete:
		delete(m, id)
		reply(w, nil)
	default:
		reply(w, o)
	}
}