package tools

import (
	"context"
	"fmt"
	"sync"
	"sync/atomic"
	"time"

	"github.com/dapicom-ai/omnipus/pkg/providers"
)

// SubTurnSpawner is an interface for spawning sub-turns.
// This avoids circular dependency between tools and agent packages.
type SubTurnSpawner interface {
	SpawnSubTurn(ctx context.Context, cfg SubTurnConfig) (*ToolResult, error)
}

// SubTurnConfig holds configuration for spawning a sub-turn.
type SubTurnConfig struct {
	Model              string
	Tools              []Tool
	SystemPrompt       string
	MaxTokens          int
	Temperature        float64
	Async              bool          // true for async (spawn), false for sync (subagent)
	Critical           bool          // continue running after parent finishes gracefully
	Timeout            time.Duration // 0 = use default (5 minutes)
	MaxContextRunes    int           // 0 = auto, -1 = no limit, >0 = explicit limit
	ActualSystemPrompt string
	InitialMessages    []providers.Message
	InitialTokenBudget *atomic.Int64 // Shared token budget for team members; nil if no budget
	// TaskLabel is the optional human-readable label for the sub-turn task (FR-H-004).
	// Populated from the spawn tool's "label" argument. Used in the subagent_start WS frame.
	TaskLabel string
}

type SubagentTask struct {
	ID            string
	Task          string
	Label         string
	AgentID       string
	OriginChannel string
	OriginChatID  string
	Status        string
	Result        string
	Created       int64
}

type SpawnSubTurnFunc func(
	ctx context.Context,
	task, label, agentID string,
	tools *ToolRegistry,
	maxTokens int,
	temperature float64,
	hasMaxTokens, hasTemperature bool,
) (*ToolResult, error)

type SubagentManager struct {
	tasks          map[string]*SubagentTask
	mu             sync.RWMutex
	provider       providers.LLMProvider
	defaultModel   string
	workspace      string
	tools          *ToolRegistry
	maxIterations  int
	maxTokens      int
	temperature    float64
	hasMaxTokens   bool
	hasTemperature bool
	nextID         int
	spawner        SpawnSubTurnFunc
}

func NewSubagentManager(
	provider providers.LLMProvider,
	defaultModel, workspace string,
) *SubagentManager {
	return &SubagentManager{
		tasks:         make(map[string]*SubagentTask),
		provider:      provider,
		defaultModel:  defaultModel,
		workspace:     workspace,
		tools:         NewToolRegistry(),
		maxIterations: 10,
		nextID:        1,
	}
}

func (sm *SubagentManager) SetSpawner(spawner SpawnSubTurnFunc) {
	sm.mu.Lock()
	defer sm.mu.Unlock()
	sm.spawner = spawner
}

// SetLLMOptions sets max tokens and temperature for subagent LLM calls.
func (sm *SubagentManager) SetLLMOptions(maxTokens int, temperature float64) {
	sm.mu.Lock()
	defer sm.mu.Unlock()
	sm.maxTokens = maxTokens
	sm.hasMaxTokens = true
	sm.temperature = temperature
	sm.hasTemperature = true
}

// SetTools sets the tool registry for subagent execution.
// If not set, subagent will have access to the provided tools.
func (sm *SubagentManager) SetTools(tools *ToolRegistry) {
	sm.mu.Lock()
	defer sm.mu.Unlock()
	sm.tools = tools
}

// RegisterTool registers a tool for subagent execution.
func (sm *SubagentManager) RegisterTool(tool Tool) {
	sm.mu.Lock()
	defer sm.mu.Unlock()
	sm.tools.Register(tool)
}

func (sm *SubagentManager) Spawn(
	ctx context.Context,
	task, label, agentID, originChannel, originChatID string,
	callback AsyncCallback,
) (string, error) {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	taskID := fmt.Sprintf("subagent-%d", sm.nextID)
	sm.nextID++

	subagentTask := &SubagentTask{
		ID:            taskID,
		Task:          task,
		Label:         label,
		AgentID:       agentID,
		OriginChannel: originChannel,
		OriginChatID:  originChatID,
		Status:        "running",
		Created:       time.Now().UnixMilli(),
	}
	sm.tasks[taskID] = subagentTask

	// Start task in background with context cancellation support
	go sm.runTask(ctx, subagentTask, callback)

	if label != "" {
		return fmt.Sprintf("Spawned subagent '%s' for task: %s", label, task), nil
	}
	return fmt.Sprintf("Spawned subagent for task: %s", task), nil
}

func (sm *SubagentManager) runTask(
	ctx context.Context,
	task *SubagentTask,
	callback AsyncCallback,
) {
	// Status and Created are already set in Spawn while holding sm.mu.Lock(),
	// so we must not write them here without the lock (data race with GetTask/ListTaskCopies).
	// TODO(eventbus): once subagents are modeled as child turns inside
	// pkg/agent, emit SubTurnEnd and SubTurnResultDelivered from the parent
	// AgentLoop instead of this legacy manager.

	// Check if context is already canceled before starting
	select {
	case <-ctx.Done():
		sm.mu.Lock()
		task.Status = "canceled"
		task.Result = "Task canceled before execution"
		sm.mu.Unlock()
		return
	default:
	}

	sm.mu.RLock()
	spawner := sm.spawner
	tools := sm.tools
	maxIter := sm.maxIterations
	maxTokens := sm.maxTokens
	temperature := sm.temperature
	hasMaxTokens := sm.hasMaxTokens
	hasTemperature := sm.hasTemperature
	sm.mu.RUnlock()

	var result *ToolResult
	var err error

	if spawner != nil {
		result, err = spawner(
			ctx,
			task.Task,
			task.Label,
			task.AgentID,
			tools,
			maxTokens,
			temperature,
			hasMaxTokens,
			hasTemperature,
		)
	} else {
		// Fallback to legacy RunToolLoop
		systemPrompt := `You are a subagent. Complete the given task independently and report the result.
You have access to tools - use them as needed to complete your task.
After completing the task, provide a clear summary of what was done.`

		messages := []providers.Message{
			{Role: "system", Content: systemPrompt},
			{Role: "user", Content: task.Task},
		}

		var llmOptions map[string]any
		if hasMaxTokens || hasTemperature {
			llmOptions = map[string]any{}
			if hasMaxTokens {
				llmOptions["max_tokens"] = maxTokens
			}
			if hasTemperature {
				llmOptions["temperature"] = temperature
			}
		}

		var loopResult *ToolLoopResult
		loopResult, err = RunToolLoop(ctx, ToolLoopConfig{
			Provider:      sm.provider,
			Model:         sm.defaultModel,
			Tools:         tools,
			MaxIterations: maxIter,
			LLMOptions:    llmOptions,
		}, messages, task.OriginChannel, task.OriginChatID)

		if err == nil {
			result = &ToolResult{
				ForLLM: fmt.Sprintf(
					"Subagent '%s' completed (iterations: %d): %s",
					task.Label,
					loopResult.Iterations,
					loopResult.Content,
				),
				ForUser: loopResult.Content,
				Silent:  false,
				IsError: false,
				Async:   false,
			}
		}
	}

	sm.mu.Lock()
	defer func() {
		sm.mu.Unlock()
		// Call callback if provided and result is set
		if callback != nil && result != nil {
			callback(ctx, result)
		}
	}()

	if err != nil {
		task.Status = "failed"
		task.Result = fmt.Sprintf("Error: %v", err)
		// Check if it was canceled
		if ctx.Err() != nil {
			task.Status = "canceled"
			task.Result = "Task canceled during execution"
		}
		result = &ToolResult{
			ForLLM:  task.Result,
			ForUser: "",
			Silent:  false,
			IsError: true,
			Async:   false,
			Err:     err,
		}
	} else {
		task.Status = "completed"
		task.Result = result.ForLLM
	}
}

// GetTask has been removed (H6). Use GetTaskCopy to avoid exposing mutable pointers.

// GetTaskCopy returns a copy of the task with the given ID, taken under the
// read lock, so the caller receives a consistent snapshot with no data race.
func (sm *SubagentManager) GetTaskCopy(taskID string) (SubagentTask, bool) {
	sm.mu.RLock()
	defer sm.mu.RUnlock()
	task, ok := sm.tasks[taskID]
	if !ok {
		return SubagentTask{}, false
	}
	return *task, true
}

// ListTasks has been removed (H6). Use ListTaskCopies to avoid exposing mutable pointers.

// ListTaskCopies returns value copies of all tasks, taken under the read lock,
// so callers receive consistent snapshots with no data race.
func (sm *SubagentManager) ListTaskCopies() []SubagentTask {
	sm.mu.RLock()
	defer sm.mu.RUnlock()

	copies := make([]SubagentTask, 0, len(sm.tasks))
	for _, task := range sm.tasks {
		copies = append(copies, *task)
	}
	return copies
}

// SubagentTool executes a subagent task synchronously and returns the result.
// It directly calls SubTurnSpawner with Async=false for synchronous execution.
type SubagentTool struct {
	BaseTool
	spawner      SubTurnSpawner
	defaultModel string
	maxTokens    int
	temperature  float64
}

func NewSubagentTool(manager *SubagentManager) *SubagentTool {
	if manager == nil {
		return &SubagentTool{}
	}
	return &SubagentTool{
		defaultModel: manager.defaultModel,
		maxTokens:    manager.maxTokens,
		temperature:  manager.temperature,
	}
}

// SetSpawner sets the SubTurnSpawner for direct sub-turn execution.
func (t *SubagentTool) SetSpawner(spawner SubTurnSpawner) {
	t.spawner = spawner
}

func (t *SubagentTool) Name() string {
	return "subagent"
}

func (t *SubagentTool) Description() string {
	return "Execute a subagent task synchronously and return the result. Use this for delegating specific tasks to an independent agent instance. Returns execution summary to user and full details to LLM."
}

func (t *SubagentTool) Scope() ToolScope { return ScopeCore }

func (t *SubagentTool) Parameters() map[string]any {
	return map[string]any{
		"type": "object",
		"properties": map[string]any{
			"task": map[string]any{
				"type":        "string",
				"description": "The task for subagent to complete",
			},
			"label": map[string]any{
				"type":        "string",
				"description": "Optional short label for the task (for display)",
			},
		},
		"required": []string{"task"},
	}
}

func (t *SubagentTool) Execute(ctx context.Context, args map[string]any) *ToolResult {
	task, ok := args["task"].(string)
	if !ok {
		return ErrorResult("task is required").WithError(fmt.Errorf("task parameter is required"))
	}

	label, _ := args["label"].(string)

	// Build system prompt for subagent
	systemPrompt := fmt.Sprintf(
		`You are a subagent. Complete the given task independently and provide a clear, concise result.

Task: %s`,
		task,
	)

	if label != "" {
		systemPrompt = fmt.Sprintf(
			`You are a subagent labeled "%s". Complete the given task independently and provide a clear, concise result.

Task: %s`,
			label,
			task,
		)
	}

	// Use spawner if available (direct SpawnSubTurn call)
	if t.spawner != nil {
		result, err := t.spawner.SpawnSubTurn(ctx, SubTurnConfig{
			Model:        t.defaultModel,
			Tools:        nil, // Will inherit from parent via context
			SystemPrompt: systemPrompt,
			MaxTokens:    t.maxTokens,
			Temperature:  t.temperature,
			Async:        false, // Synchronous execution
		})
		if err != nil {
			return ErrorResult(fmt.Sprintf("Subagent execution failed: %v", err)).WithError(err)
		}

		// Format result for display
		userContent := result.ForLLM
		if result.ForUser != "" {
			userContent = result.ForUser
		}
		maxUserLen := 500
		if len(userContent) > maxUserLen {
			userContent = userContent[:maxUserLen] + "..."
		}

		labelStr := label
		if labelStr == "" {
			labelStr = "(unnamed)"
		}
		llmContent := fmt.Sprintf("Subagent task completed:\nLabel: %s\nResult: %s",
			labelStr, result.ForLLM)

		return &ToolResult{
			ForLLM:  llmContent,
			ForUser: userContent,
			Silent:  false,
			IsError: result.IsError,
			Async:   false,
		}
	}

	// Fallback: spawner not configured
	return ErrorResult("Subagent manager not configured").WithError(fmt.Errorf("spawner not set"))
}
