package skill

import (
	"context"
	"sort"
	"sync"
	"time"
)

// Memory is a zero-dependency in-process SkillStore — a light host or test gets
// saved-skill persistence with no DB. Mort backs SkillStore with GORM/MySQL;
// contrib/store adds durable SQLite.
type Memory struct {
	mu       sync.RWMutex
	skills   map[string]*Skill         // by ID
	versions map[string][]SkillVersion // by skill ID, append order
	byVerID  map[string]SkillVersion   // by version ID
}

// NewMemory returns an empty in-memory SkillStore.
func NewMemory() *Memory {
	return &Memory{
		skills:   map[string]*Skill{},
		versions: map[string][]SkillVersion{},
		byVerID:  map[string]SkillVersion{},
	}
}

var _ SkillStore = (*Memory)(nil)

func (m *Memory) Initialize(context.Context) error { return nil }

func (m *Memory) Save(_ context.Context, s *Skill) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	cp := *s
	m.skills[s.ID] = &cp
	return nil
}

func (m *Memory) Get(_ context.Context, id string) (*Skill, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	s, ok := m.skills[id]
	if !ok {
		return nil, ErrNotFound
	}
	cp := *s
	return &cp, nil
}

func (m *Memory) GetByName(_ context.Context, ownerID, name string) (*Skill, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	for _, s := range m.skills {
		if s.OwnerID == ownerID && s.Name == name {
			cp := *s
			return &cp, nil
		}
	}
	return nil, ErrNotFound
}

func (m *Memory) Delete(_ context.Context, id string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	delete(m.skills, id)
	return nil
}

func (m *Memory) listWhere(keep func(*Skill) bool) []Skill {
	m.mu.RLock()
	defer m.mu.RUnlock()
	out := make([]Skill, 0, len(m.skills))
	for _, s := range m.skills {
		if keep == nil || keep(s) {
			out = append(out, *s)
		}
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
	return out
}

func (m *Memory) ListByOwner(_ context.Context, ownerID string) ([]Skill, error) {
	return m.listWhere(func(s *Skill) bool { return s.OwnerID == ownerID }), nil
}

func (m *Memory) ListPublic(context.Context) ([]Skill, error) {
	return m.listWhere(func(s *Skill) bool { return s.Visibility == VisibilityPublic }), nil
}

func (m *Memory) ListSharedWith(_ context.Context, memberID string) ([]Skill, error) {
	return m.listWhere(func(s *Skill) bool {
		if s.Visibility != VisibilityShared {
			return false
		}
		for _, id := range s.SharedWith {
			if id == memberID {
				return true
			}
		}
		return false
	}), nil
}

func (m *Memory) ListBuiltinByName(_ context.Context, name string) (*Skill, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	for _, s := range m.skills {
		if s.Source == SourceBuiltin && s.Name == name {
			cp := *s
			return &cp, nil
		}
	}
	return nil, ErrNotFound
}

func (m *Memory) ListChatbotExposed(context.Context) ([]Skill, error) {
	return m.listWhere(func(s *Skill) bool { return s.ExposeAsChatbotTool }), nil
}

func (m *Memory) ListDueScheduled(_ context.Context, now time.Time) ([]Skill, error) {
	return m.listWhere(func(s *Skill) bool { return s.DueAt(now) }), nil
}

func (m *Memory) MarkScheduledRun(_ context.Context, skillID string, ranAt, nextAt time.Time) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	s, ok := m.skills[skillID]
	if !ok {
		return ErrNotFound
	}
	s.LastScheduledRunAt = ranAt
	s.NextRunAt = nextAt
	return nil
}

func (m *Memory) AppendVersion(_ context.Context, sv SkillVersion) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.versions[sv.SkillID] = append(m.versions[sv.SkillID], sv)
	m.byVerID[sv.ID] = sv
	return nil
}

func (m *Memory) ListVersionsBySkill(_ context.Context, skillID string, limit int) ([]SkillVersion, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	all := m.versions[skillID]
	// newest first
	out := make([]SkillVersion, 0, len(all))
	for i := len(all) - 1; i >= 0; i-- {
		out = append(out, all[i])
		if limit > 0 && len(out) >= limit {
			break
		}
	}
	return out, nil
}

func (m *Memory) GetVersionByID(_ context.Context, versionID string) (*SkillVersion, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	sv, ok := m.byVerID[versionID]
	if !ok {
		return nil, ErrNotFound
	}
	return &sv, nil
}