package computer

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sync"
	"time"

	"github.com/gooseek/backend/internal/computer/connectors"
	"github.com/gooseek/backend/internal/llm"
	"github.com/google/uuid"
)

type ComputerConfig struct {
	MaxParallelTasks    int
	MaxSubTasks         int
	TaskTimeout         time.Duration
	SubTaskTimeout      time.Duration
	TotalBudget         float64
	EnableSandbox       bool
	EnableScheduling    bool
	EnableBrowser       bool
	SandboxImage        string
	ArtifactStorageURL  string
	BrowserServerURL    string
	CheckpointStorePath string
	MaxConcurrentTasks  int
	HeartbeatInterval   time.Duration
	CheckpointInterval  time.Duration
}

func DefaultConfig() ComputerConfig {
	return ComputerConfig{
		MaxParallelTasks:    10,
		MaxSubTasks:         100,
		TaskTimeout:         365 * 24 * time.Hour,
		SubTaskTimeout:      2 * time.Hour,
		TotalBudget:         100.0,
		EnableSandbox:       true,
		EnableScheduling:    true,
		EnableBrowser:       true,
		SandboxImage:        "gooseek/sandbox:latest",
		BrowserServerURL:    "http://browser-svc:3050",
		CheckpointStorePath: "/data/checkpoints",
		MaxConcurrentTasks:  50,
		HeartbeatInterval:   30 * time.Second,
		CheckpointInterval:  15 * time.Minute,
	}
}

func GetDurationConfig(mode DurationMode) (maxDuration, checkpointFreq, heartbeatFreq time.Duration, maxIter int) {
	cfg, ok := DurationModeConfigs[mode]
	if !ok {
		cfg = DurationModeConfigs[DurationMedium]
	}
	return cfg.MaxDuration, cfg.CheckpointFreq, cfg.HeartbeatFreq, cfg.MaxIterations
}

type Dependencies struct {
	Registry     *llm.ModelRegistry
	TaskRepo     TaskRepository
	MemoryRepo   MemoryRepository
	ArtifactRepo ArtifactRepository
}

type TaskRepository interface {
	Create(ctx context.Context, task *ComputerTask) error
	Update(ctx context.Context, task *ComputerTask) error
	GetByID(ctx context.Context, id string) (*ComputerTask, error)
	GetByUserID(ctx context.Context, userID string, limit, offset int) ([]ComputerTask, error)
	GetScheduled(ctx context.Context) ([]ComputerTask, error)
	Delete(ctx context.Context, id string) error
}

type MemoryRepository interface {
	Store(ctx context.Context, entry *MemoryEntry) error
	GetByUser(ctx context.Context, userID string, limit int) ([]MemoryEntry, error)
	GetByTask(ctx context.Context, taskID string) ([]MemoryEntry, error)
	Search(ctx context.Context, userID, query string, limit int) ([]MemoryEntry, error)
	Delete(ctx context.Context, id string) error
}

type ArtifactRepository interface {
	Create(ctx context.Context, artifact *Artifact) error
	GetByID(ctx context.Context, id string) (*Artifact, error)
	GetByTaskID(ctx context.Context, taskID string) ([]Artifact, error)
	Delete(ctx context.Context, id string) error
}

type Computer struct {
	cfg        ComputerConfig
	planner    *Planner
	router     *Router
	executor   *Executor
	sandbox    *SandboxManager
	memory     *MemoryStore
	scheduler  *Scheduler
	connectors *connectors.ConnectorHub
	registry   *llm.ModelRegistry
	taskRepo   TaskRepository
	eventBus   *EventBus
	mu         sync.RWMutex
	tasks      map[string]*ComputerTask
}

func NewComputer(cfg ComputerConfig, deps Dependencies) *Computer {
	eventBus := NewEventBus()

	c := &Computer{
		cfg:      cfg,
		registry: deps.Registry,
		taskRepo: deps.TaskRepo,
		eventBus: eventBus,
		tasks:    make(map[string]*ComputerTask),
	}

	c.planner = NewPlanner(deps.Registry)
	c.router = NewRouter(deps.Registry)
	c.executor = NewExecutor(c.router, cfg.MaxParallelTasks)
	c.memory = NewMemoryStore(deps.MemoryRepo)
	c.connectors = connectors.NewConnectorHub()

	if cfg.EnableSandbox {
		c.sandbox = NewSandboxManager(SandboxConfig{
			Image:   cfg.SandboxImage,
			Timeout: cfg.SubTaskTimeout,
		})
		c.executor.SetSandbox(c.sandbox)
	}

	if cfg.EnableScheduling {
		c.scheduler = NewScheduler(deps.TaskRepo, c)
	}

	return c
}

func (c *Computer) Execute(ctx context.Context, userID, query string, opts ExecuteOptions) (*ComputerTask, error) {
	if opts.ResumeFromID != "" {
		return c.resumeFromCheckpoint(ctx, opts.ResumeFromID, opts)
	}

	durationMode := opts.DurationMode
	if durationMode == "" {
		durationMode = DurationMedium
	}

	maxDuration, _, _, maxIter := GetDurationConfig(durationMode)

	task := &ComputerTask{
		ID:            uuid.New().String(),
		UserID:        userID,
		Query:         query,
		Status:        StatusPending,
		Memory:        make(map[string]interface{}),
		CreatedAt:     time.Now(),
		UpdatedAt:     time.Now(),
		DurationMode:  durationMode,
		MaxDuration:   maxDuration,
		MaxIterations: maxIter,
		Priority:      opts.Priority,
	}

	if opts.Priority == "" {
		task.Priority = PriorityNormal
	}

	if opts.ResourceLimits != nil {
		task.ResourceLimits = opts.ResourceLimits
	}

	if opts.Schedule != nil {
		task.Schedule = opts.Schedule
		task.Status = StatusScheduled
	}

	if opts.Context != nil {
		task.Memory = opts.Context
	}

	estimatedEnd := time.Now().Add(maxDuration)
	task.EstimatedEnd = &estimatedEnd

	if err := c.taskRepo.Create(ctx, task); err != nil {
		return nil, fmt.Errorf("failed to create task: %w", err)
	}

	c.mu.Lock()
	c.tasks[task.ID] = task
	c.mu.Unlock()

	c.emitEvent(TaskEvent{
		Type:      EventTaskCreated,
		TaskID:    task.ID,
		Status:    task.Status,
		Message:   fmt.Sprintf("Task created (mode: %s, max duration: %v)", durationMode, maxDuration),
		Timestamp: time.Now(),
		Data: map[string]interface{}{
			"durationMode":  durationMode,
			"maxDuration":   maxDuration.String(),
			"maxIterations": maxIter,
		},
	})

	if opts.Async {
		go c.executeTaskWithCheckpoints(context.Background(), task, opts)
		return task, nil
	}

	return c.executeTaskWithCheckpoints(ctx, task, opts)
}

func (c *Computer) resumeFromCheckpoint(ctx context.Context, checkpointID string, opts ExecuteOptions) (*ComputerTask, error) {
	task, err := c.taskRepo.GetByID(ctx, checkpointID)
	if err != nil {
		return nil, fmt.Errorf("task not found: %w", err)
	}

	if task.Checkpoint == nil {
		return nil, errors.New("no checkpoint found for this task")
	}

	task.Status = StatusExecuting
	now := time.Now()
	task.ResumedAt = &now
	task.UpdatedAt = now

	c.emitEvent(TaskEvent{
		Type:      EventResumed,
		TaskID:    task.ID,
		Status:    task.Status,
		Message:   fmt.Sprintf("Resumed from checkpoint (wave: %d, subtask: %d)", task.Checkpoint.WaveIndex, task.Checkpoint.SubTaskIndex),
		Progress:  task.Checkpoint.Progress,
		Timestamp: time.Now(),
	})

	c.mu.Lock()
	c.tasks[task.ID] = task
	c.mu.Unlock()

	if opts.Async {
		go c.executeTaskWithCheckpoints(context.Background(), task, opts)
		return task, nil
	}

	return c.executeTaskWithCheckpoints(ctx, task, opts)
}

func (c *Computer) executeTask(ctx context.Context, task *ComputerTask, opts ExecuteOptions) (*ComputerTask, error) {
	return c.executeTaskWithCheckpoints(ctx, task, opts)
}

func (c *Computer) executeTaskWithCheckpoints(ctx context.Context, task *ComputerTask, opts ExecuteOptions) (*ComputerTask, error) {
	maxDuration, checkpointFreq, heartbeatFreq, _ := GetDurationConfig(task.DurationMode)

	if opts.Timeout > 0 {
		maxDuration = time.Duration(opts.Timeout) * time.Second
	}

	ctx, cancel := context.WithTimeout(ctx, maxDuration)
	defer cancel()

	budget := c.cfg.TotalBudget
	if opts.MaxCost > 0 {
		budget = opts.MaxCost
	}
	if task.ResourceLimits != nil && task.ResourceLimits.MaxTotalCost > 0 {
		budget = task.ResourceLimits.MaxTotalCost
	}

	startWave := 0
	if task.Checkpoint != nil {
		startWave = task.Checkpoint.WaveIndex
		for k, v := range task.Checkpoint.Memory {
			task.Memory[k] = v
		}
	}

	if task.Plan == nil {
		task.Status = StatusPlanning
		task.UpdatedAt = time.Now()
		c.updateTask(ctx, task)

		c.emitEvent(TaskEvent{
			Type:      EventTaskStarted,
			TaskID:    task.ID,
			Status:    StatusPlanning,
			Message:   "Planning task execution",
			Timestamp: time.Now(),
		})

		userMemory, _ := c.memory.GetUserContext(ctx, task.UserID)
		memoryContext := make(map[string]interface{})
		for k, v := range userMemory {
			memoryContext[k] = v
		}
		for k, v := range task.Memory {
			memoryContext[k] = v
		}

		plan, err := c.planner.Plan(ctx, task.Query, memoryContext)
		if err != nil {
			task.Status = StatusFailed
			task.Error = fmt.Sprintf("Planning failed: %v", err)
			task.UpdatedAt = time.Now()
			c.updateTask(ctx, task)
			c.emitEvent(TaskEvent{
				Type:      EventTaskFailed,
				TaskID:    task.ID,
				Status:    StatusFailed,
				Message:   task.Error,
				Timestamp: time.Now(),
			})
			return task, err
		}

		task.Plan = plan
		task.SubTasks = plan.SubTasks
	}

	task.Status = StatusLongRunning
	task.UpdatedAt = time.Now()
	c.updateTask(ctx, task)

	c.emitEvent(TaskEvent{
		Type:     EventTaskProgress,
		TaskID:   task.ID,
		Status:   StatusLongRunning,
		Progress: 10,
		Message:  fmt.Sprintf("Executing %d subtasks (long-running mode)", len(task.Plan.SubTasks)),
		Data: map[string]interface{}{
			"plan":           task.Plan,
			"durationMode":   task.DurationMode,
			"checkpointFreq": checkpointFreq.String(),
		},
		Timestamp: time.Now(),
	})

	heartbeatTicker := time.NewTicker(heartbeatFreq)
	defer heartbeatTicker.Stop()

	checkpointTicker := time.NewTicker(checkpointFreq)
	defer checkpointTicker.Stop()

	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			case <-heartbeatTicker.C:
				now := time.Now()
				task.HeartbeatAt = &now
				c.emitEvent(TaskEvent{
					Type:     EventHeartbeat,
					TaskID:   task.ID,
					Progress: task.Progress,
					Message:  fmt.Sprintf("Heartbeat: %d%% complete, cost: $%.4f", task.Progress, task.TotalCost),
					Data: map[string]interface{}{
						"runtime": time.Since(task.CreatedAt).String(),
						"cost":    task.TotalCost,
					},
					Timestamp: now,
				})
			}
		}
	}()

	totalSubTasks := len(task.Plan.ExecutionOrder)
	for waveIdx := startWave; waveIdx < totalSubTasks; waveIdx++ {
		select {
		case <-ctx.Done():
			c.saveCheckpoint(task, waveIdx, 0, "context_timeout")
			return task, ctx.Err()
		case <-checkpointTicker.C:
			c.saveCheckpoint(task, waveIdx, 0, "periodic")
		default:
		}

		if budget > 0 && task.TotalCost >= budget {
			c.saveCheckpoint(task, waveIdx, 0, "budget_exceeded")
			task.Status = StatusPaused
			task.Message = fmt.Sprintf("Paused: budget exceeded ($%.2f / $%.2f)", task.TotalCost, budget)
			c.updateTask(ctx, task)
			return task, nil
		}

		wave := task.Plan.ExecutionOrder[waveIdx]
		waveTasks := make([]SubTask, 0)
		for _, subTaskID := range wave {
			for i := range task.SubTasks {
				if task.SubTasks[i].ID == subTaskID {
					waveTasks = append(waveTasks, task.SubTasks[i])
					break
				}
			}
		}

		results, err := c.executor.ExecuteGroup(ctx, waveTasks, budget-task.TotalCost)
		if err != nil {
			c.saveCheckpoint(task, waveIdx, 0, "execution_error")
			task.Status = StatusFailed
			task.Error = fmt.Sprintf("Execution failed at wave %d: %v", waveIdx, err)
			task.UpdatedAt = time.Now()
			c.updateTask(ctx, task)
			return task, err
		}

		for _, result := range results {
			for i := range task.SubTasks {
				if task.SubTasks[i].ID == result.SubTaskID {
					task.SubTasks[i].Output = result.Output
					task.SubTasks[i].Cost = result.Cost
					task.SubTasks[i].Status = StatusCompleted
					now := time.Now()
					task.SubTasks[i].CompletedAt = &now
					if result.Error != nil {
						task.SubTasks[i].Status = StatusFailed
						task.SubTasks[i].Error = result.Error.Error()
					}
					break
				}
			}

			task.TotalCost += result.Cost
			task.TotalRuntime = time.Since(task.CreatedAt)

			for _, artifact := range result.Artifacts {
				task.Artifacts = append(task.Artifacts, artifact)
				c.emitEvent(TaskEvent{
					Type:      EventArtifact,
					TaskID:    task.ID,
					SubTaskID: result.SubTaskID,
					Data: map[string]interface{}{
						"artifact": artifact,
					},
					Timestamp: time.Now(),
				})
			}
		}

		progress := 10 + int(float64(waveIdx+1)/float64(totalSubTasks)*80)
		task.Progress = progress
		task.Iterations = waveIdx + 1
		task.UpdatedAt = time.Now()
		c.updateTask(ctx, task)

		c.emitEvent(TaskEvent{
			Type:     EventIteration,
			TaskID:   task.ID,
			Progress: progress,
			Message:  fmt.Sprintf("Completed wave %d/%d (runtime: %v)", waveIdx+1, totalSubTasks, time.Since(task.CreatedAt).Round(time.Second)),
			Data: map[string]interface{}{
				"wave":      waveIdx + 1,
				"total":     totalSubTasks,
				"cost":      task.TotalCost,
				"runtime":   time.Since(task.CreatedAt).String(),
				"artifacts": len(task.Artifacts),
			},
			Timestamp: time.Now(),
		})
	}

	task.Status = StatusCompleted
	task.Progress = 100
	now := time.Now()
	task.CompletedAt = &now
	task.UpdatedAt = now
	task.TotalRuntime = time.Since(task.CreatedAt)
	c.updateTask(ctx, task)

	c.emitEvent(TaskEvent{
		Type:     EventTaskCompleted,
		TaskID:   task.ID,
		Status:   StatusCompleted,
		Progress: 100,
		Message:  fmt.Sprintf("Task completed (runtime: %v, cost: $%.4f)", task.TotalRuntime.Round(time.Second), task.TotalCost),
		Data: map[string]interface{}{
			"artifacts":    task.Artifacts,
			"totalCost":    task.TotalCost,
			"totalRuntime": task.TotalRuntime.String(),
			"iterations":   task.Iterations,
		},
		Timestamp: time.Now(),
	})

	c.storeTaskResults(ctx, task)

	return task, nil
}

func (c *Computer) saveCheckpoint(task *ComputerTask, waveIdx, subTaskIdx int, reason string) {
	checkpoint := Checkpoint{
		ID:           uuid.New().String(),
		TaskID:       task.ID,
		WaveIndex:    waveIdx,
		SubTaskIndex: subTaskIdx,
		State:        make(map[string]interface{}),
		Progress:     task.Progress,
		Memory:       task.Memory,
		CreatedAt:    time.Now(),
		RuntimeSoFar: time.Since(task.CreatedAt),
		CostSoFar:    task.TotalCost,
		Reason:       reason,
	}

	for _, artifact := range task.Artifacts {
		checkpoint.Artifacts = append(checkpoint.Artifacts, artifact.ID)
	}

	task.Checkpoint = &checkpoint
	task.Checkpoints = append(task.Checkpoints, checkpoint)
	task.UpdatedAt = time.Now()

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	c.taskRepo.Update(ctx, task)

	c.emitEvent(TaskEvent{
		Type:     EventCheckpointSaved,
		TaskID:   task.ID,
		Progress: task.Progress,
		Message:  fmt.Sprintf("Checkpoint saved: %s (wave %d)", reason, waveIdx),
		Data: map[string]interface{}{
			"checkpointId": checkpoint.ID,
			"waveIndex":    waveIdx,
			"subTaskIndex": subTaskIdx,
			"reason":       reason,
			"runtime":      checkpoint.RuntimeSoFar.String(),
			"cost":         checkpoint.CostSoFar,
		},
		Timestamp: time.Now(),
	})
}

func (c *Computer) Pause(ctx context.Context, taskID string) error {
	c.mu.Lock()
	task, ok := c.tasks[taskID]
	if !ok {
		c.mu.Unlock()
		var err error
		task, err = c.taskRepo.GetByID(ctx, taskID)
		if err != nil {
			return err
		}
		c.mu.Lock()
	}

	if task.Status != StatusExecuting && task.Status != StatusLongRunning {
		c.mu.Unlock()
		return errors.New("task is not running")
	}

	now := time.Now()
	task.Status = StatusPaused
	task.PausedAt = &now
	task.UpdatedAt = now
	c.mu.Unlock()

	c.saveCheckpoint(task, task.Iterations, 0, "user_paused")

	c.emitEvent(TaskEvent{
		Type:      EventPaused,
		TaskID:    taskID,
		Status:    StatusPaused,
		Progress:  task.Progress,
		Message:   "Task paused by user",
		Timestamp: now,
	})

	return c.taskRepo.Update(ctx, task)
}

func (c *Computer) Resume(ctx context.Context, taskID string, userInput string) error {
	c.mu.RLock()
	task, ok := c.tasks[taskID]
	c.mu.RUnlock()

	if !ok {
		var err error
		task, err = c.taskRepo.GetByID(ctx, taskID)
		if err != nil {
			return fmt.Errorf("task not found: %w", err)
		}
	}

	if task.Status != StatusWaiting {
		return errors.New("task is not waiting for user input")
	}

	task.Memory["user_input"] = userInput
	task.Status = StatusExecuting
	task.UpdatedAt = time.Now()

	go c.executeTask(context.Background(), task, ExecuteOptions{Async: true})

	return nil
}

func (c *Computer) Cancel(ctx context.Context, taskID string) error {
	c.mu.Lock()
	task, ok := c.tasks[taskID]
	if ok {
		task.Status = StatusCancelled
		task.UpdatedAt = time.Now()
	}
	c.mu.Unlock()

	if !ok {
		task, err := c.taskRepo.GetByID(ctx, taskID)
		if err != nil {
			return fmt.Errorf("task not found: %w", err)
		}
		task.Status = StatusCancelled
		task.UpdatedAt = time.Now()
		return c.taskRepo.Update(ctx, task)
	}

	c.emitEvent(TaskEvent{
		Type:      EventTaskFailed,
		TaskID:    taskID,
		Status:    StatusCancelled,
		Message:   "Task cancelled by user",
		Timestamp: time.Now(),
	})

	return c.taskRepo.Update(ctx, task)
}

func (c *Computer) GetStatus(ctx context.Context, taskID string) (*ComputerTask, error) {
	c.mu.RLock()
	task, ok := c.tasks[taskID]
	c.mu.RUnlock()

	if ok {
		return task, nil
	}

	return c.taskRepo.GetByID(ctx, taskID)
}

func (c *Computer) GetUserTasks(ctx context.Context, userID string, limit, offset int) ([]ComputerTask, error) {
	return c.taskRepo.GetByUserID(ctx, userID, limit, offset)
}

func (c *Computer) Stream(ctx context.Context, taskID string) (<-chan TaskEvent, error) {
	return c.eventBus.Subscribe(taskID), nil
}

func (c *Computer) updateTask(ctx context.Context, task *ComputerTask) {
	c.mu.Lock()
	c.tasks[task.ID] = task
	c.mu.Unlock()

	_ = c.taskRepo.Update(ctx, task)
}

func (c *Computer) emitEvent(event TaskEvent) {
	c.eventBus.Publish(event.TaskID, event)
}

func (c *Computer) storeTaskResults(ctx context.Context, task *ComputerTask) {
	for _, st := range task.SubTasks {
		if st.Output != nil {
			outputJSON, _ := json.Marshal(st.Output)
			entry := &MemoryEntry{
				ID:        uuid.New().String(),
				UserID:    task.UserID,
				TaskID:    task.ID,
				Key:       fmt.Sprintf("subtask_%s_result", st.ID),
				Value:     string(outputJSON),
				Type:      MemoryTypeResult,
				CreatedAt: time.Now(),
			}
			_ = c.memory.Store(ctx, task.UserID, entry)
		}
	}
}

func (c *Computer) StartScheduler(ctx context.Context) {
	if c.scheduler != nil {
		c.scheduler.Start(ctx)
	}
}

func (c *Computer) StopScheduler() {
	if c.scheduler != nil {
		c.scheduler.Stop()
	}
}

type EventBus struct {
	subscribers map[string][]chan TaskEvent
	mu          sync.RWMutex
}

func NewEventBus() *EventBus {
	return &EventBus{
		subscribers: make(map[string][]chan TaskEvent),
	}
}

func (eb *EventBus) Subscribe(taskID string) <-chan TaskEvent {
	eb.mu.Lock()
	defer eb.mu.Unlock()

	ch := make(chan TaskEvent, 100)
	eb.subscribers[taskID] = append(eb.subscribers[taskID], ch)
	return ch
}

func (eb *EventBus) Unsubscribe(taskID string, ch <-chan TaskEvent) {
	eb.mu.Lock()
	defer eb.mu.Unlock()

	subs := eb.subscribers[taskID]
	for i, sub := range subs {
		if sub == ch {
			eb.subscribers[taskID] = append(subs[:i], subs[i+1:]...)
			close(sub)
			break
		}
	}
}

func (eb *EventBus) Publish(taskID string, event TaskEvent) {
	eb.mu.RLock()
	subs := eb.subscribers[taskID]
	eb.mu.RUnlock()

	for _, ch := range subs {
		select {
		case ch <- event:
		default:
		}
	}
}