package editor

import (
	"sync"

	"pad/internal/browser"
	"pad/internal/io/pool"
	"pad/internal/io/pool/mock"
	"pad/internal/ui"
)

// ConfigEvent represents a window configuration change (resize, orientation).
// PixelWidth and PixelHeight are the raw pixel dimensions from Gio.
type ConfigEvent struct {
	PixelWidth  int
	PixelHeight int
}

// ScaleEvent represents a metric change (HiDPI scale factor).
type ScaleEvent struct {
	Scale float32
}

// ConfigUpdate is a common interface for all configuration updates.
// Both ConfigEvent and ScaleEvent implement this interface.
type ConfigUpdate interface {
	apply(*State)
}

func (e ConfigEvent) apply(s *State) {
	s.PixelWidth = e.PixelWidth
	s.PixelHeight = e.PixelHeight
}

func (e ScaleEvent) apply(s *State) {
	s.SetScale(e.Scale)
}

// ResultEvent represents a completed async task result.
type ResultEvent struct {
	// Future: add result fields here
}

// Logic runs the logic goroutine and provides channels for communication.
type Logic struct {
	state            *State
	configChan       chan ConfigUpdate
	frameChan        chan []ui.Element
	inputChan        chan []ui.InputEvent
	lastLineYChan    chan int // last line Y (Dp, sent as int) feedback from renderer
	resultChan       chan ResultEvent
	searchQueryChan  chan string // search text updates from main goroutine
	workerPool       *pool.WorkerPool
	mockFS           *mock.FileSystem
	mu               sync.Mutex
	done             chan struct{}
}

// NewLogic creates a new Logic instance.
func NewLogic() *Logic {
	state := NewState()
	TheState = state

	// Initialize mock filesystem with sample data
	mockFS := mock.NewFileSystem()
	populateMockFileSystem(mockFS)

	// Initialize worker pool
	wp := pool.NewWorkerPool(4)
	wp.Start()

	// Set browser initial path to mock root
	state.Browser.CurrentPath = "/"

	return &Logic{
		state:           state,
		configChan:      make(chan ConfigUpdate),
		frameChan:       make(chan []ui.Element),
		inputChan:       make(chan []ui.InputEvent),
		lastLineYChan:   make(chan int),
		resultChan:      make(chan ResultEvent),
		searchQueryChan: make(chan string),
		workerPool:      wp,
		mockFS:          mockFS,
		done:            make(chan struct{}),
	}
}

// ConfigChan returns the unified config channel for the logic goroutine.
// Accepts ConfigEvent (size) and ScaleEvent (scale factor).
func (l *Logic) ConfigChan() chan<- ConfigUpdate {
	return l.configChan
}

// FrameChan returns the frame channel for the logic goroutine.
func (l *Logic) FrameChan() <-chan []ui.Element {
	return l.frameChan
}



// InputChan returns the input channel for the logic goroutine.
func (l *Logic) InputChan() chan<- []ui.InputEvent {
	return l.inputChan
}

// DisplayLineChan returns the last line Y feedback channel.
func (l *Logic) DisplayLineChan() chan<- int {
	return l.lastLineYChan
}

// ResultChan returns the result channel for the logic goroutine.
func (l *Logic) ResultChan() chan<- ResultEvent {
	return l.resultChan
}

// SearchQueryChan returns the search query channel for the logic goroutine.
// The main goroutine sends updated search text here when it detects a change.
func (l *Logic) SearchQueryChan() chan<- string {
	return l.searchQueryChan
}

// TheState is the global editor state, set once at startup.
var TheState *State

// Scale returns the current scale factor (pixels per DP).
func (l *Logic) Scale() float32 {
	return l.state.Scale()
}

// Run runs the logic goroutine loop.
func (l *Logic) Run() {
	// Dispatch initial directory index build on startup
	l.workerPool.Dispatch(pool.NewBuildIndexTask(l.state.Browser.CurrentPath, l.mockFS))

	for {
		select {
		case <-l.done:
			return
		case update := <-l.configChan:
			update.apply(l.state)
			l.frameChan <- l.state.layout()
		case y := <-l.lastLineYChan:
			if ui.Dp(y) != l.state.LastLineY {
				l.state.LastLineY = ui.Dp(y)
				l.frameChan <- l.state.layout()
			}
		case events := <-l.inputChan:
			for _, evt := range events {
				evt.Handler(evt.Data)
			}
			l.frameChan <- l.state.layout()
		case query := <-l.searchQueryChan:
			if query != l.state.Browser.Query {
				l.state.Browser.Query = query
				if l.state.page == BrowserPage {
					browser.HandleSearch(&l.state.Browser, query)
				}
			}
			l.frameChan <- l.state.layout()
		case res := <-l.workerPool.ResultChan():
			l.handleWorkerResult(res)
		case <-l.resultChan:
			l.frameChan <- l.state.layout()
		}
	}
}

// handleWorkerResult processes results from the worker pool.
func (l *Logic) handleWorkerResult(res pool.Result) {
	switch res.TaskType {
	case pool.TypeBuildIndex:
		l.applyBuildIndexResult(res)
	case pool.TypeLoadPages:
		l.applyLoadPagesResult(res)
	case pool.TypeReadDir:
		l.applyReadDirResult(res)
	}
	l.frameChan <- l.state.layout()
}

// applyBuildIndexResult applies a completed BuildIndexTask result to browser state.
func (l *Logic) applyBuildIndexResult(res pool.Result) {
	if !res.Success {
		return
	}
	// Convert mock DirEntry results to browser entries
	if entries, ok := res.Data.([]mock.DirEntry); ok {
		l.state.Browser.TotalEntries = len(entries)
		// Build the in-memory index with position maps
		l.state.Browser.SortIndex = buildBrowserIndex(entries)
		// Load initial visible pages from the index into the Pages map
		browser.LoadInitialPages(&l.state.Browser)
	}
}

// applyLoadPagesResult applies a completed LoadPagesTask result to browser state.
func (l *Logic) applyLoadPagesResult(res pool.Result) {
	_ = res // TODO: implement page loading from worker results
}

// applyReadDirResult applies a completed ReadDirTask result to browser state.
func (l *Logic) applyReadDirResult(res pool.Result) {
	_ = res // TODO: implement directory read result handling
}

// State returns the current state.
func (l *Logic) State() *State {
	return l.state
}

// Done signals the logic goroutine to stop.
func (l *Logic) Done() {
	close(l.done)
}