package world

import (
	"fmt"
	"math/rand"
	"os"
	"path/filepath"
	"strings"
	"sync"

	"gopkg.in/yaml.v3"
)

type LootEntry struct {
	ItemID   string `yaml:"item_id"`
	Weight   int    `yaml:"weight"`
	Quantity int    `yaml:"quantity"`
}

type DropTable struct {
	Remains string      `yaml:"remains"`
	Loot    []LootEntry `yaml:"loot"`
}

type MobDef struct {
	ID                 string    `yaml:"id"`
	Name               string    `yaml:"name"`
	Description        string    `yaml:"description"`
	IdleDescriptions   []string  `yaml:"idle_descriptions"`
	CombatDescriptions []string  `yaml:"combat_descriptions"`
	Attack             int       `yaml:"attack"`
	Strength           int       `yaml:"strength"`
	Defense            int       `yaml:"defense"`
	HP                 int       `yaml:"hp"`
	Speed              int       `yaml:"speed"`
	Aggressive         bool      `yaml:"aggressive"`
	Protected          bool      `yaml:"protected"`
	Unique             bool      `yaml:"unique"`
	RespawnTicks       int       `yaml:"respawn_ticks"`
	Wander             int       `yaml:"wander"`
	WanderTick         int       `yaml:"wander_tick"`
	WanderChance       float64   `yaml:"wander_chance"`
	Drops              DropTable `yaml:"drops"`
}

type MobInstance struct {
	InstanceID       string
	DefID            string
	Name             string
	HP               int
	MaxHP            int
	Attack           int
	Strength         int
	Defense          int
	Speed            int
	Aggressive       bool
	Protected        bool
	Unique           bool
	RespawnTicks     int
	RoomID           int
	HomeRoomID       int
	Drops            DropTable
	IdleDescription  string
	Wander           int
	WanderTick       int
	WanderChance      float64
	WanderTickCounter int
	regenerateTick    int
}

const (
	MatchNone   = 0
	MatchPrefix = 1
	MatchExact  = 2
)

func WordPrefixMatch(input, name string) bool {
	lower := strings.ToLower(input)
	for _, word := range strings.Fields(name) {
		if strings.HasPrefix(strings.ToLower(word), lower) {
			return true
		}
	}
	return false
}

func (m *MobInstance) MatchQuality(input string) int {
	lower := strings.ToLower(input)
	if strings.ToLower(m.Name) == lower {
		return MatchExact
	}
	if WordPrefixMatch(input, m.Name) {
		return MatchPrefix
	}
	return MatchNone
}

func pickIdleDescription(descriptions []string) string {
	if len(descriptions) == 0 {
		return ""
	}
	return descriptions[rand.Intn(len(descriptions))]
}

func (m *MobInstance) StartRegen() {
	if m.regenerateTick == 0 {
		m.regenerateTick = 100
	}
}

type MobStore struct {
	dataDir   string
	mu        sync.Mutex
	defs      map[string]*MobDef
	instances map[string]*MobInstance
}

func NewMobStore(dataDir string) *MobStore {
	return &MobStore{
		dataDir:   dataDir,
		defs:      make(map[string]*MobDef),
		instances: make(map[string]*MobInstance),
	}
}

func (s *MobStore) LoadDef(id string) (*MobDef, error) {
	s.mu.Lock()
	if def, ok := s.defs[id]; ok {
		s.mu.Unlock()
		return def, nil
	}
	s.mu.Unlock()

	path := filepath.Join(s.dataDir, "mobs", id+".yaml")
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read mob %s: %w", id, err)
	}
	var def MobDef
	if err := yaml.Unmarshal(data, &def); err != nil {
		return nil, fmt.Errorf("parse mob %s: %w", id, err)
	}

	s.mu.Lock()
	s.defs[id] = &def
	s.mu.Unlock()
	return &def, nil
}

func (s *MobStore) SpawnMob(defID string, roomID int, instanceID string) (*MobInstance, error) {
	def, err := s.LoadDef(defID)
	if err != nil {
		return nil, err
	}
	s.mu.Lock()
	defer s.mu.Unlock()
	inst := &MobInstance{
		InstanceID:   instanceID,
		DefID:        defID,
		Name:         def.Name,
		HP:           def.HP,
		MaxHP:        def.HP,
		Attack:       def.Attack,
		Strength:     def.Strength,
		Defense:      def.Defense,
		Speed:        def.Speed,
		Aggressive:   def.Aggressive,
		RespawnTicks: def.RespawnTicks,
		RoomID:       roomID,
		Drops:        def.Drops,
	}
	s.instances[instanceID] = inst
	return inst, nil
}

func (s *MobStore) GetInstance(id string) *MobInstance {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.instances[id]
}

func (s *MobStore) RemoveInstance(id string) {
	s.mu.Lock()
	defer s.mu.Unlock()
	delete(s.instances, id)
}

func (s *MobStore) AllInstances() []*MobInstance {
	s.mu.Lock()
	defer s.mu.Unlock()
	var out []*MobInstance
	for _, inst := range s.instances {
		out = append(out, inst)
	}
	return out
}

func (s *MobStore) MobsInRoom(roomID int) []*MobInstance {
	s.mu.Lock()
	defer s.mu.Unlock()
	var out []*MobInstance
	for _, inst := range s.instances {
		if inst.RoomID == roomID && inst.HP > 0 {
			out = append(out, inst)
		}
	}
	return out
}

func (s *MobStore) Tick() {
	s.mu.Lock()
	defer s.mu.Unlock()

	for _, inst := range s.instances {
		if inst.HP <= 0 || inst.HP >= inst.MaxHP {
			inst.regenerateTick = 0
			continue
		}
		inst.regenerateTick--
		if inst.regenerateTick <= 0 {
			inst.HP++
			if inst.HP >= inst.MaxHP {
				inst.HP = inst.MaxHP
				inst.regenerateTick = 0
			} else {
				inst.regenerateTick = 100
			}
		}
	}
}

func (s *MobStore) RollIdleDescription(inst *MobInstance) {
	def, err := s.LoadDef(inst.DefID)
	if err != nil {
		return
	}
	inst.IdleDescription = pickIdleDescription(def.IdleDescriptions)
	inst.Wander = def.Wander
	inst.WanderTick = def.WanderTick
	inst.WanderChance = def.WanderChance
	inst.WanderTickCounter = 0
}

func (s *MobStore) SeedMobs(roomID int, mobIDs []string) {
	type defWrapper struct {
		def *MobDef
		err error
	}
	defs := make([]defWrapper, len(mobIDs))
	for i, defID := range mobIDs {
		d, err := s.LoadDef(defID)
		defs[i] = defWrapper{d, err}
	}

	s.mu.Lock()
	defer s.mu.Unlock()
	for i, dw := range defs {
		if dw.err != nil {
			continue
		}
		defID := mobIDs[i]
		instID := fmt.Sprintf("%s_%d_%d", defID, roomID, i)
		if inst, exists := s.instances[instID]; exists {
			// Already exists — skip (respawn is handled by timers)
			_ = inst
			continue
		}
		inst := &MobInstance{
			InstanceID:     instID,
			DefID:          defID,
			Name:           dw.def.Name,
			HP:             dw.def.HP,
			MaxHP:          dw.def.HP,
			Attack:         dw.def.Attack,
			Strength:       dw.def.Strength,
			Defense:        dw.def.Defense,
			Speed:          dw.def.Speed,
			Aggressive:     dw.def.Aggressive,
			Protected:      dw.def.Protected,
			Unique:         dw.def.Unique,
			RespawnTicks:   dw.def.RespawnTicks,
			Wander:         dw.def.Wander,
			WanderTick:     dw.def.WanderTick,
			WanderChance:   dw.def.WanderChance,
			RoomID:         roomID,
			HomeRoomID:     roomID,
			Drops:          dw.def.Drops,
		}
		inst.IdleDescription = pickIdleDescription(dw.def.IdleDescriptions)
		s.instances[instID] = inst
	}
}