package services

import (
	lucifer3 "git.aiterp.net/lucifer3/server"
	"git.aiterp.net/lucifer3/server/commands"
	"git.aiterp.net/lucifer3/server/device"
	"git.aiterp.net/lucifer3/server/events"
	"github.com/gobwas/glob"
	"sort"
	"strings"
	"sync"
)

func NewResolver() *Resolver {
	return &Resolver{
		pointers:     make([]*device.Pointer, 0, 128),
		patternCache: make(map[string]glob.Glob),
	}
}

// Resolver implements both device.Resolver and lucifer3.Service. There should be only one of them as it keeps its
// state from event-sourcery.
type Resolver struct {
	mu           sync.Mutex
	pointers     []*device.Pointer
	patternCache map[string]glob.Glob
}

func (r *Resolver) resolve(pattern string) []*device.Pointer {
	g := r.patternToGlob(pattern)
	if g == nil {
		return []*device.Pointer{}
	}

	res := make([]*device.Pointer, 0, 32)
	for _, ptr := range r.pointers {
		if ptr.Matches(g) {
			res = append(res, ptr)
		}
	}

	return res
}

func (r *Resolver) Resolve(pattern string) []device.Pointer {
	r.mu.Lock()
	defer r.mu.Unlock()

	g := r.patternToGlob(pattern)
	if g == nil {
		return []device.Pointer{}
	}

	res := make([]device.Pointer, 0, 32)
	for _, ptr := range r.pointers {
		if ptr.Matches(g) {
			res = append(res, *ptr)
		}
	}

	return res
}

func (r *Resolver) Active() bool {
	return true
}

func (r *Resolver) HandleEvent(_ *lucifer3.EventBus, event lucifer3.Event) {
	switch event := event.(type) {
	// On HardwareState, use the internal name if (and only if) it is not already named.
	case events.HardwareState:
		r.mu.Lock()
		ptr := r.ensure(event.ID)
		if event.InternalName != "" && ptr.Name() == "" {
			ptr.AddAlias("lucifer:name:" + event.InternalName)
			r.sortPointers()
		}
		r.mu.Unlock()
	}
}

func (r *Resolver) HandleCommand(bus *lucifer3.EventBus, command lucifer3.Command) {
	var aliasEvents []lucifer3.Event

	switch command := command.(type) {
	case commands.AddAlias:
		r.mu.Lock()
		for _, ptr := range r.resolve(command.Match) {
			added, removed := ptr.AddAlias(command.Alias)

			if added != nil {
				aliasEvents = append(aliasEvents, events.AliasAdded{
					ID:    ptr.ID,
					Alias: *added,
				})
			}
			if removed != nil {
				aliasEvents = append(aliasEvents, events.AliasRemoved{
					ID:    ptr.ID,
					Alias: *removed,
				})
			}
		}
		if strings.HasPrefix(command.Alias, "lucifer:name:") {
			r.sortPointers()
		}
		r.mu.Unlock()

	case commands.RemoveAlias:
		r.mu.Lock()
		for _, ptr := range r.resolve(command.Match) {
			if ptr.RemoveAlias(command.Alias) {
				aliasEvents = append(aliasEvents, events.AliasRemoved{
					ID:    ptr.ID,
					Alias: command.Alias,
				})
			}
		}
		if strings.HasPrefix(command.Alias, "lucifer:name:") {
			r.sortPointers()
		}
		r.mu.Unlock()
	}

	if len(aliasEvents) > 0 {
		go bus.RunEvents(aliasEvents)
	}
}

func (r *Resolver) ensure(id string) *device.Pointer {
	for _, ptr := range r.pointers {
		if ptr.ID == id {
			return ptr
		}
	}

	r.pointers = append(r.pointers, &device.Pointer{
		ID: id,
	})

	return r.pointers[len(r.pointers)-1]
}

func (r *Resolver) patternToGlob(pattern string) glob.Glob {
	if cached, ok := r.patternCache[pattern]; ok {
		return cached
	}

	g, err := glob.Compile(pattern, ':')
	if err != nil {
		return nil
	}

	// Keep this in bounds. Random cache deletions after 128 length.
	if len(r.patternCache) > 128 {
		i := 64
		for k := range r.patternCache {
			if i == 0 {
				break
			}

			delete(r.patternCache, k)
			i -= 1
		}
	}

	// Cache it
	r.patternCache[pattern] = g

	return g
}

func (r *Resolver) sortPointers() {
	sort.Slice(r.pointers, func(i, j int) bool {
		ni := r.pointers[i].Name()
		nj := r.pointers[j].Name()

		if ni == nj {
			return r.pointers[i].ID < r.pointers[j].ID
		}
		if ni == "" {
			return false
		}
		if nj == "" {
			return true
		}

		return ni < nj
	})
}