package search

import (
	"context"
	"fmt"
	"reflect"
	"sync"
	"time"

	"github.com/google/uuid"

	"github.com/anotherhadi/iknowyou/config"
	"github.com/anotherhadi/iknowyou/internal/tools"
)

type Manager struct {
	mu       sync.RWMutex
	searches map[string]*Search

	configPath      string
	factories       []func() tools.ToolRunner
	searchTTL       time.Duration
	cleanupInterval time.Duration

	done chan struct{} // closed by Stop()
}

func NewManager(configPath string, factories []func() tools.ToolRunner, searchTTL, cleanupInterval time.Duration) *Manager {
	m := &Manager{
		searches:        make(map[string]*Search),
		configPath:      configPath,
		factories:       factories,
		searchTTL:       searchTTL,
		cleanupInterval: cleanupInterval,
		done:            make(chan struct{}),
	}
	go m.cleanupLoop()
	return m
}

func (m *Manager) Stop() {
	close(m.done)
}

func (m *Manager) Start(
	parentCtx context.Context,
	target string,
	inputType tools.InputType,
	profileName string,
) (*Search, error) {

	// "default" is the canonical UI name for the no-filter profile.
	if profileName == "default" {
		profileName = ""
	}

	cfg, err := config.Load(m.configPath)
	if err != nil {
		return nil, fmt.Errorf("manager: loading config: %w", err)
	}

	activeTools, statuses, err := m.instantiate(cfg, inputType, profileName)
	if err != nil {
		return nil, err
	}

	ctx, cancel := context.WithCancel(parentCtx)

	s := &Search{
		ID:           uuid.NewString(),
		Target:       target,
		InputType:    inputType,
		Profile:      profileName,
		StartedAt:    time.Now(),
		PlannedTools: statuses,
		cancelFn:     cancel,
		status:       StatusRunning,
	}

	m.mu.Lock()
	m.searches[s.ID] = s
	m.mu.Unlock()

	go m.runAll(ctx, s, activeTools)

	return s, nil
}

func (m *Manager) Get(id string) (*Search, error) {
	return m.get(id)
}

func (m *Manager) All() []*Search {
	m.mu.RLock()
	defer m.mu.RUnlock()
	out := make([]*Search, 0, len(m.searches))
	for _, s := range m.searches {
		out = append(out, s)
	}
	return out
}

func (m *Manager) Delete(id string) error {
	s, err := m.get(id)
	if err != nil {
		return err
	}
	s.Cancel()

	m.mu.Lock()
	delete(m.searches, id)
	m.mu.Unlock()
	return nil
}

func (m *Manager) cleanupLoop() {
	ticker := time.NewTicker(m.cleanupInterval)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			m.purgeExpired()
		case <-m.done:
			return
		}
	}
}

func (m *Manager) purgeExpired() {
	now := time.Now()
	m.mu.Lock()
	defer m.mu.Unlock()
	for id, s := range m.searches {
		ft := s.FinishedAt()
		if ft.IsZero() {
			continue // still running
		}
		if now.Sub(ft) > m.searchTTL {
			delete(m.searches, id)
		}
	}
}

func (m *Manager) instantiate(cfg *config.Config, inputType tools.InputType, profileName string) ([]tools.ToolRunner, []ToolStatus, error) {
	allNames := make([]string, len(m.factories))
	allInstances := make([]tools.ToolRunner, len(m.factories))
	for i, factory := range m.factories {
		t := factory()
		allNames[i] = t.Name()
		allInstances[i] = t
	}

	activeNames, err := cfg.ActiveTools(profileName, allNames)
	if err != nil {
		return nil, nil, err
	}
	activeSet := make(map[string]struct{}, len(activeNames))
	for _, n := range activeNames {
		activeSet[n] = struct{}{}
	}

	var runners []tools.ToolRunner
	var statuses []ToolStatus

	for _, tool := range allInstances {
		if _, ok := activeSet[tool.Name()]; !ok {
			continue
		}
		if !acceptsInputType(tool, inputType) {
			continue
		}

		if a, ok := tool.(tools.AvailabilityChecker); ok {
			if available, reason := a.Available(); !available {
				statuses = append(statuses, ToolStatus{
					Name:    tool.Name(),
					Skipped: true,
					Reason:  reason,
				})
				continue
			}
		}

		if c, ok := tool.(tools.Configurable); ok {
			if err := cfg.DecodeEffective(tool.Name(), profileName, c.ConfigPtr()); err != nil {
				return nil, nil, fmt.Errorf("manager: configuring tool %q: %w", tool.Name(), err)
			}

			if d, ok := tool.(tools.ConfigDescriber); ok {
				if missing, fieldName := missingRequiredField(d.ConfigFields()); missing {
					statuses = append(statuses, ToolStatus{
						Name:    tool.Name(),
						Skipped: true,
						Reason:  fmt.Sprintf("missing required config field: %s", fieldName),
					})
					continue
				}
			}
		}

		statuses = append(statuses, ToolStatus{Name: tool.Name()})
		runners = append(runners, tool)
	}

	return runners, statuses, nil
}

func (m *Manager) runAll(ctx context.Context, s *Search, runners []tools.ToolRunner) {
	var wg sync.WaitGroup
	for _, tool := range runners {
		wg.Add(1)
		go func(t tools.ToolRunner) {
			defer wg.Done()
			m.runOne(ctx, s, t)
		}(tool)
	}
	wg.Wait()
	s.markDone()
}

func (m *Manager) runOne(ctx context.Context, s *Search, tool tools.ToolRunner) {
	out := make(chan tools.Event)
	go func() {
		_ = tool.Run(ctx, s.Target, s.InputType, out)
	}()

	var count int
	var hasCount bool
	for e := range out {
		if e.Type == tools.EventTypeCount {
			if n, ok := e.Payload.(int); ok {
				count += n
				hasCount = true
			}
			continue
		}
		s.append(e)
	}

	if hasCount {
		s.setToolResultCount(tool.Name(), count)
	}
}

func (m *Manager) get(id string) (*Search, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	s, ok := m.searches[id]
	if !ok {
		return nil, fmt.Errorf("search %q not found", id)
	}
	return s, nil
}

func acceptsInputType(tool tools.ToolRunner, inputType tools.InputType) bool {
	for _, t := range tool.InputTypes() {
		if t == inputType {
			return true
		}
	}
	return false
}

func missingRequiredField(fields []tools.ConfigField) (missing bool, fieldName string) {
	for _, f := range fields {
		if !f.Required {
			continue
		}
		if f.Value == nil || reflect.DeepEqual(f.Value, reflect.Zero(reflect.TypeOf(f.Value)).Interface()) {
			return true, f.Name
		}
	}
	return false, ""
}