package agent

import (
	"context"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/iomodo/staff/git"
	"github.com/iomodo/staff/llm"
	"github.com/iomodo/staff/tm"
)

// AgentConfig contains configuration for the agent
type AgentConfig struct {
	Name        string
	Role        string
	GitUsername string
	GitEmail    string
	WorkingDir  string

	// LLM Configuration
	LLMProvider llm.Provider
	LLMModel    string
	LLMConfig   llm.Config

	// System prompt for the agent
	SystemPrompt string

	// Task Manager Configuration
	TaskManager tm.TaskManager

	// Git Configuration
	GitRepoPath string
	GitRemote   string
	GitBranch   string
}

// Agent represents an AI agent that can process tasks
type Agent struct {
	Config       AgentConfig
	llmProvider  llm.LLMProvider
	gitInterface git.GitInterface
	ctx          context.Context
	cancel       context.CancelFunc
}

// NewAgent creates a new agent instance
func NewAgent(config AgentConfig) (*Agent, error) {
	// Validate configuration
	if err := validateConfig(config); err != nil {
		return nil, fmt.Errorf("invalid config: %w", err)
	}

	// Create LLM provider
	llmProvider, err := llm.CreateProvider(config.LLMConfig)
	if err != nil {
		return nil, fmt.Errorf("failed to create LLM provider: %w", err)
	}

	// Create git interface
	gitInterface := git.DefaultGit(config.GitRepoPath)

	// Create context with cancellation
	ctx, cancel := context.WithCancel(context.Background())

	agent := &Agent{
		Config:       config,
		llmProvider:  llmProvider,
		gitInterface: gitInterface,
		ctx:          ctx,
		cancel:       cancel,
	}

	return agent, nil
}

// validateConfig validates the agent configuration
func validateConfig(config AgentConfig) error {
	if config.Name == "" {
		return fmt.Errorf("agent name is required")
	}
	if config.Role == "" {
		return fmt.Errorf("agent role is required")
	}
	if config.WorkingDir == "" {
		return fmt.Errorf("working directory is required")
	}
	if config.SystemPrompt == "" {
		return fmt.Errorf("system prompt is required")
	}
	if config.TaskManager == nil {
		return fmt.Errorf("task manager is required")
	}
	if config.GitRepoPath == "" {
		return fmt.Errorf("git repository path is required")
	}
	return nil
}

// Run starts the agent's main loop
func (a *Agent) Run() error {
	log.Printf("Starting agent %s (%s)", a.Config.Name, a.Config.Role)
	defer log.Printf("Agent %s stopped", a.Config.Name)

	// Initialize git repository if needed
	if err := a.initializeGit(); err != nil {
		return fmt.Errorf("failed to initialize git: %w", err)
	}

	// Main agent loop
	for {
		select {
		case <-a.ctx.Done():
			return a.ctx.Err()
		default:
			if err := a.processNextTask(); err != nil {
				log.Printf("Error processing task: %v", err)
				// Continue running even if there's an error
				time.Sleep(30 * time.Second)
			}
		}
	}
}

// Stop stops the agent
func (a *Agent) Stop() {
	log.Printf("Stopping agent %s", a.Config.Name)
	a.cancel()
	if a.llmProvider != nil {
		a.llmProvider.Close()
	}
}

// initializeGit initializes the git repository
func (a *Agent) initializeGit() error {
	ctx := context.Background()

	// Check if repository exists
	isRepo, err := a.gitInterface.IsRepository(ctx, a.Config.GitRepoPath)
	if err != nil {
		return fmt.Errorf("failed to check repository: %w", err)
	}

	if !isRepo {
		// Initialize new repository
		if err := a.gitInterface.Init(ctx, a.Config.GitRepoPath); err != nil {
			return fmt.Errorf("failed to initialize repository: %w", err)
		}
	}

	// Checkout to the specified branch
	if a.Config.GitBranch != "" {
		if err := a.gitInterface.Checkout(ctx, a.Config.GitBranch); err != nil {
			// Try to create the branch if it doesn't exist
			if err := a.gitInterface.CreateBranch(ctx, a.Config.GitBranch, ""); err != nil {
				return fmt.Errorf("failed to create branch %s: %w", a.Config.GitBranch, err)
			}
		}
	}

	return nil
}

// processNextTask processes the next available task
func (a *Agent) processNextTask() error {
	ctx := context.Background()

	// Get tasks assigned to this agent
	taskList, err := a.Config.TaskManager.GetTasksByOwner(ctx, a.Config.Name, 0, 10)
	if err != nil {
		return fmt.Errorf("failed to get tasks: %w", err)
	}

	// Find a task that's ready to be worked on
	var taskToProcess *tm.Task
	for _, task := range taskList.Tasks {
		if task.Status == tm.StatusToDo {
			taskToProcess = task
			break
		}
	}

	if taskToProcess == nil {
		// No tasks to process, wait a bit
		time.Sleep(60 * time.Second)
		return nil
	}

	log.Printf("Processing task: %s - %s", taskToProcess.ID, taskToProcess.Title)

	// Start the task
	startedTask, err := a.Config.TaskManager.StartTask(ctx, taskToProcess.ID)
	if err != nil {
		return fmt.Errorf("failed to start task: %w", err)
	}

	// Process the task with LLM
	solution, err := a.processTaskWithLLM(startedTask)
	if err != nil {
		// Mark task as failed or retry
		log.Printf("Failed to process task with LLM: %v", err)
		return err
	}

	// Create PR with the solution
	if err := a.createPullRequest(startedTask, solution); err != nil {
		return fmt.Errorf("failed to create pull request: %w", err)
	}

	// Complete the task
	if _, err := a.Config.TaskManager.CompleteTask(ctx, startedTask.ID); err != nil {
		return fmt.Errorf("failed to complete task: %w", err)
	}

	log.Printf("Successfully completed task: %s", startedTask.ID)
	return nil
}

// processTaskWithLLM sends the task to the LLM and gets a solution
func (a *Agent) processTaskWithLLM(task *tm.Task) (string, error) {
	ctx := context.Background()

	// Prepare the prompt
	prompt := a.buildTaskPrompt(task)

	// Create chat completion request
	req := llm.ChatCompletionRequest{
		Model: a.Config.LLMModel,
		Messages: []llm.Message{
			{
				Role:    llm.RoleSystem,
				Content: a.Config.SystemPrompt,
			},
			{
				Role:    llm.RoleUser,
				Content: prompt,
			},
		},
		MaxTokens:   intPtr(4000),
		Temperature: float64Ptr(0.7),
	}

	// Get response from LLM
	resp, err := a.llmProvider.ChatCompletion(ctx, req)
	if err != nil {
		return "", fmt.Errorf("LLM chat completion failed: %w", err)
	}

	if len(resp.Choices) == 0 {
		return "", fmt.Errorf("no response from LLM")
	}

	return resp.Choices[0].Message.Content, nil
}

// buildTaskPrompt builds the prompt for the LLM based on the task
func (a *Agent) buildTaskPrompt(task *tm.Task) string {
	var prompt strings.Builder

	prompt.WriteString(fmt.Sprintf("Task ID: %s\n", task.ID))
	prompt.WriteString(fmt.Sprintf("Title: %s\n", task.Title))
	prompt.WriteString(fmt.Sprintf("Priority: %s\n", task.Priority))

	if task.Description != "" {
		prompt.WriteString(fmt.Sprintf("Description: %s\n", task.Description))
	}

	if task.DueDate != nil {
		prompt.WriteString(fmt.Sprintf("Due Date: %s\n", task.DueDate.Format("2006-01-02")))
	}

	prompt.WriteString("\nPlease provide a detailed solution for this task. ")
	prompt.WriteString("Include any code, documentation, or other deliverables as needed. ")
	prompt.WriteString("Format your response appropriately for the type of task.")

	return prompt.String()
}

// createPullRequest creates a pull request with the solution
func (a *Agent) createPullRequest(task *tm.Task, solution string) error {
	ctx := context.Background()

	// Generate branch name
	branchName := a.generateBranchName(task)

	// Create and checkout to new branch
	if err := a.gitInterface.CreateBranch(ctx, branchName, ""); err != nil {
		return fmt.Errorf("failed to create branch: %w", err)
	}

	if err := a.gitInterface.Checkout(ctx, branchName); err != nil {
		return fmt.Errorf("failed to checkout branch: %w", err)
	}

	// Create solution file
	solutionPath := filepath.Join(a.Config.WorkingDir, fmt.Sprintf("task-%s-solution.md", task.ID))
	solutionContent := a.formatSolution(task, solution)

	if err := os.WriteFile(solutionPath, []byte(solutionContent), 0644); err != nil {
		return fmt.Errorf("failed to write solution file: %w", err)
	}

	// Add and commit the solution
	if err := a.gitInterface.Add(ctx, []string{solutionPath}); err != nil {
		return fmt.Errorf("failed to add solution file: %w", err)
	}

	commitMessage := fmt.Sprintf("feat: Complete task %s - %s", task.ID, task.Title)
	if err := a.gitInterface.Commit(ctx, commitMessage, git.CommitOptions{
		Author: &git.Author{
			Name:  a.Config.GitUsername,
			Email: a.Config.GitEmail,
			Time:  time.Now(),
		},
	}); err != nil {
		return fmt.Errorf("failed to commit solution: %w", err)
	}

	// Push the branch
	if err := a.gitInterface.Push(ctx, "origin", branchName, git.PushOptions{SetUpstream: true}); err != nil {
		return fmt.Errorf("failed to push branch: %w", err)
	}

	log.Printf("Created pull request for task %s on branch %s", task.ID, branchName)
	return nil
}

// generateBranchName generates a branch name for the task
func (a *Agent) generateBranchName(task *tm.Task) string {
	// Clean the task title for branch name
	cleanTitle := strings.ReplaceAll(task.Title, " ", "-")
	cleanTitle = strings.ToLower(cleanTitle)

	// Remove special characters that are not allowed in git branch names
	// Keep only alphanumeric characters and hyphens
	var result strings.Builder
	for _, char := range cleanTitle {
		if (char >= 'a' && char <= 'z') || (char >= '0' && char <= '9') || char == '-' {
			result.WriteRune(char)
		}
	}
	cleanTitle = result.String()

	// Remove consecutive hyphens
	for strings.Contains(cleanTitle, "--") {
		cleanTitle = strings.ReplaceAll(cleanTitle, "--", "-")
	}

	// Remove leading and trailing hyphens
	cleanTitle = strings.Trim(cleanTitle, "-")

	// Limit length
	if len(cleanTitle) > 50 {
		cleanTitle = cleanTitle[:50]
		// Ensure we don't end with a hyphen after truncation
		cleanTitle = strings.TrimSuffix(cleanTitle, "-")
	}

	return fmt.Sprintf("task/%s-%s", task.ID, cleanTitle)
}

// formatSolution formats the solution for the pull request
func (a *Agent) formatSolution(task *tm.Task, solution string) string {
	var content strings.Builder

	content.WriteString(fmt.Sprintf("# Task Solution: %s\n\n", task.Title))
	content.WriteString(fmt.Sprintf("**Task ID:** %s\n", task.ID))
	content.WriteString(fmt.Sprintf("**Agent:** %s (%s)\n", a.Config.Name, a.Config.Role))
	content.WriteString(fmt.Sprintf("**Completed:** %s\n\n", time.Now().Format("2006-01-02 15:04:05")))

	content.WriteString("## Task Description\n\n")
	content.WriteString(task.Description)
	content.WriteString("\n\n")

	content.WriteString("## Solution\n\n")
	content.WriteString(solution)
	content.WriteString("\n\n")

	content.WriteString("---\n")
	content.WriteString("*This solution was generated by AI Agent*\n")

	return content.String()
}

// ptr helpers for cleaner code
func intPtr(i int) *int {
	return &i
}

func float64Ptr(f float64) *float64 {
	return &f
}