package providers

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"

	"chorus/pkg/repository"
)

// GiteaProvider implements TaskProvider for Gitea API
type GiteaProvider struct {
	config     *repository.Config
	httpClient *http.Client
	baseURL    string
	token      string
	owner      string
	repo       string
}

// NewGiteaProvider creates a new Gitea provider
func NewGiteaProvider(config *repository.Config) (*GiteaProvider, error) {
	if config.BaseURL == "" {
		return nil, fmt.Errorf("base URL is required for Gitea provider")
	}
	if config.AccessToken == "" {
		return nil, fmt.Errorf("access token is required for Gitea provider")
	}
	if config.Owner == "" {
		return nil, fmt.Errorf("owner is required for Gitea provider")
	}
	if config.Repository == "" {
		return nil, fmt.Errorf("repository name is required for Gitea provider")
	}

	// Ensure base URL has proper format
	baseURL := strings.TrimSuffix(config.BaseURL, "/")
	if !strings.HasPrefix(baseURL, "http") {
		baseURL = "https://" + baseURL
	}

	return &GiteaProvider{
		config:  config,
		baseURL: baseURL,
		token:   config.AccessToken,
		owner:   config.Owner,
		repo:    config.Repository,
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
	}, nil
}

// GiteaIssue represents a Gitea issue
type GiteaIssue struct {
	ID          int64     `json:"id"`
	Number      int       `json:"number"`
	Title       string    `json:"title"`
	Body        string    `json:"body"`
	State       string    `json:"state"`
	Labels      []GiteaLabel `json:"labels"`
	CreatedAt   time.Time `json:"created_at"`
	UpdatedAt   time.Time `json:"updated_at"`
	Repository  *GiteaRepository `json:"repository"`
	Assignee    *GiteaUser `json:"assignee"`
	Assignees   []GiteaUser `json:"assignees"`
}

// GiteaLabel represents a Gitea label
type GiteaLabel struct {
	ID    int64  `json:"id"`
	Name  string `json:"name"`
	Color string `json:"color"`
}

// GiteaRepository represents a Gitea repository
type GiteaRepository struct {
	ID        int64  `json:"id"`
	Name      string `json:"name"`
	FullName  string `json:"full_name"`
	Owner     *GiteaUser `json:"owner"`
}

// GiteaUser represents a Gitea user
type GiteaUser struct {
	ID        int64  `json:"id"`
	Username  string `json:"username"`
	FullName  string `json:"full_name"`
	Email     string `json:"email"`
}

// GiteaComment represents a Gitea issue comment
type GiteaComment struct {
	ID        int64     `json:"id"`
	Body      string    `json:"body"`
	CreatedAt time.Time `json:"created_at"`
	User      *GiteaUser `json:"user"`
}

// makeRequest makes an HTTP request to the Gitea API
func (g *GiteaProvider) makeRequest(method, endpoint string, body interface{}) (*http.Response, error) {
	var reqBody io.Reader

	if body != nil {
		jsonData, err := json.Marshal(body)
		if err != nil {
			return nil, fmt.Errorf("failed to marshal request body: %w", err)
		}
		reqBody = bytes.NewBuffer(jsonData)
	}

	url := fmt.Sprintf("%s/api/v1%s", g.baseURL, endpoint)
	req, err := http.NewRequest(method, url, reqBody)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Authorization", "token "+g.token)
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	resp, err := g.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("request failed: %w", err)
	}

	return resp, nil
}

// GetTasks retrieves tasks (issues) from the Gitea repository
func (g *GiteaProvider) GetTasks(projectID int) ([]*repository.Task, error) {
	// Build query parameters
	params := url.Values{}
	params.Add("state", "open")
	params.Add("type", "issues")
	params.Add("sort", "created")
	params.Add("order", "desc")

	// Add task label filter if specified
	if g.config.TaskLabel != "" {
		params.Add("labels", g.config.TaskLabel)
	}

	endpoint := fmt.Sprintf("/repos/%s/%s/issues?%s", g.owner, g.repo, params.Encode())

	resp, err := g.makeRequest("GET", endpoint, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to get issues: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("API request failed with status %d: %s", resp.StatusCode, string(body))
	}

	var issues []GiteaIssue
	if err := json.NewDecoder(resp.Body).Decode(&issues); err != nil {
		return nil, fmt.Errorf("failed to decode issues: %w", err)
	}

	// Convert Gitea issues to repository tasks
	tasks := make([]*repository.Task, 0, len(issues))
	for _, issue := range issues {
		task := g.issueToTask(&issue)
		tasks = append(tasks, task)
	}

	return tasks, nil
}

// ClaimTask claims a task by assigning it to the agent and adding in-progress label
func (g *GiteaProvider) ClaimTask(taskNumber int, agentID string) (bool, error) {
	// First, get the current issue to check its state
	endpoint := fmt.Sprintf("/repos/%s/%s/issues/%d", g.owner, g.repo, taskNumber)

	resp, err := g.makeRequest("GET", endpoint, nil)
	if err != nil {
		return false, fmt.Errorf("failed to get issue: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return false, fmt.Errorf("issue not found or not accessible")
	}

	var issue GiteaIssue
	if err := json.NewDecoder(resp.Body).Decode(&issue); err != nil {
		return false, fmt.Errorf("failed to decode issue: %w", err)
	}

	// Check if issue is already assigned
	if issue.Assignee != nil {
		return false, fmt.Errorf("issue is already assigned to %s", issue.Assignee.Username)
	}

	// Add in-progress label if specified
	if g.config.InProgressLabel != "" {
		err := g.addLabelToIssue(taskNumber, g.config.InProgressLabel)
		if err != nil {
			return false, fmt.Errorf("failed to add in-progress label: %w", err)
		}
	}

	// Add a comment indicating the task has been claimed
	comment := fmt.Sprintf("🤖 Task claimed by CHORUS agent `%s`\n\nThis task is now being processed automatically.", agentID)
	err = g.addCommentToIssue(taskNumber, comment)
	if err != nil {
		// Don't fail the claim if comment fails
		fmt.Printf("Warning: failed to add claim comment: %v\n", err)
	}

	return true, nil
}

// UpdateTaskStatus updates the status of a task
func (g *GiteaProvider) UpdateTaskStatus(task *repository.Task, status string, comment string) error {
	// Add a comment with the status update
	statusComment := fmt.Sprintf("**Status Update:** %s\n\n%s", status, comment)

	err := g.addCommentToIssue(task.Number, statusComment)
	if err != nil {
		return fmt.Errorf("failed to add status comment: %w", err)
	}

	return nil
}

// CompleteTask completes a task by updating status and adding completion comment
func (g *GiteaProvider) CompleteTask(task *repository.Task, result *repository.TaskResult) error {
	// Create completion comment with results
	var commentBuffer strings.Builder
	commentBuffer.WriteString(fmt.Sprintf("✅ **Task Completed Successfully**\n\n"))
	commentBuffer.WriteString(fmt.Sprintf("**Result:** %s\n\n", result.Message))

	// Add metadata if available
	if result.Metadata != nil {
		commentBuffer.WriteString("**Execution Details:**\n")
		for key, value := range result.Metadata {
			commentBuffer.WriteString(fmt.Sprintf("- **%s:** %v\n", key, value))
		}
		commentBuffer.WriteString("\n")
	}

	commentBuffer.WriteString("🤖 Completed by CHORUS autonomous agent")

	// Add completion comment
	err := g.addCommentToIssue(task.Number, commentBuffer.String())
	if err != nil {
		return fmt.Errorf("failed to add completion comment: %w", err)
	}

	// Remove in-progress label and add completed label
	if g.config.InProgressLabel != "" {
		err := g.removeLabelFromIssue(task.Number, g.config.InProgressLabel)
		if err != nil {
			fmt.Printf("Warning: failed to remove in-progress label: %v\n", err)
		}
	}

	if g.config.CompletedLabel != "" {
		err := g.addLabelToIssue(task.Number, g.config.CompletedLabel)
		if err != nil {
			fmt.Printf("Warning: failed to add completed label: %v\n", err)
		}
	}

	// Close the issue if the task was successful
	if result.Success {
		err := g.closeIssue(task.Number)
		if err != nil {
			return fmt.Errorf("failed to close issue: %w", err)
		}
	}

	return nil
}

// GetTaskDetails retrieves detailed information about a specific task
func (g *GiteaProvider) GetTaskDetails(projectID int, taskNumber int) (*repository.Task, error) {
	endpoint := fmt.Sprintf("/repos/%s/%s/issues/%d", g.owner, g.repo, taskNumber)

	resp, err := g.makeRequest("GET", endpoint, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to get issue: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("issue not found")
	}

	var issue GiteaIssue
	if err := json.NewDecoder(resp.Body).Decode(&issue); err != nil {
		return nil, fmt.Errorf("failed to decode issue: %w", err)
	}

	return g.issueToTask(&issue), nil
}

// ListAvailableTasks lists all available (unassigned) tasks
func (g *GiteaProvider) ListAvailableTasks(projectID int) ([]*repository.Task, error) {
	// Get all open issues without assignees
	params := url.Values{}
	params.Add("state", "open")
	params.Add("type", "issues")
	params.Add("assigned", "false") // Only unassigned issues

	if g.config.TaskLabel != "" {
		params.Add("labels", g.config.TaskLabel)
	}

	endpoint := fmt.Sprintf("/repos/%s/%s/issues?%s", g.owner, g.repo, params.Encode())

	resp, err := g.makeRequest("GET", endpoint, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to get available issues: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("API request failed with status %d: %s", resp.StatusCode, string(body))
	}

	var issues []GiteaIssue
	if err := json.NewDecoder(resp.Body).Decode(&issues); err != nil {
		return nil, fmt.Errorf("failed to decode issues: %w", err)
	}

	// Convert to tasks and filter out assigned ones
	tasks := make([]*repository.Task, 0, len(issues))
	for _, issue := range issues {
		// Skip assigned issues
		if issue.Assignee != nil || len(issue.Assignees) > 0 {
			continue
		}

		task := g.issueToTask(&issue)
		tasks = append(tasks, task)
	}

	return tasks, nil
}

// Helper methods

// issueToTask converts a Gitea issue to a repository Task
func (g *GiteaProvider) issueToTask(issue *GiteaIssue) *repository.Task {
	// Extract labels
	labels := make([]string, len(issue.Labels))
	for i, label := range issue.Labels {
		labels[i] = label.Name
	}

	// Calculate priority and complexity based on labels and content
	priority := g.calculatePriority(labels, issue.Title, issue.Body)
	complexity := g.calculateComplexity(labels, issue.Title, issue.Body)

	// Determine required role and expertise from labels
	requiredRole := g.determineRequiredRole(labels)
	requiredExpertise := g.determineRequiredExpertise(labels)

	return &repository.Task{
		Number:            issue.Number,
		Title:             issue.Title,
		Body:              issue.Body,
		Repository:        fmt.Sprintf("%s/%s", g.owner, g.repo),
		Labels:            labels,
		Priority:          priority,
		Complexity:        complexity,
		Status:            issue.State,
		CreatedAt:         issue.CreatedAt,
		UpdatedAt:         issue.UpdatedAt,
		RequiredRole:      requiredRole,
		RequiredExpertise: requiredExpertise,
		Metadata: map[string]interface{}{
			"gitea_id":     issue.ID,
			"provider":     "gitea",
			"repository":   issue.Repository,
			"assignee":     issue.Assignee,
			"assignees":    issue.Assignees,
		},
	}
}

// calculatePriority determines task priority from labels and content
func (g *GiteaProvider) calculatePriority(labels []string, title, body string) int {
	priority := 5 // default

	for _, label := range labels {
		switch strings.ToLower(label) {
		case "priority:critical", "critical", "urgent":
			priority = 10
		case "priority:high", "high":
			priority = 8
		case "priority:medium", "medium":
			priority = 5
		case "priority:low", "low":
			priority = 2
		case "bug", "security", "hotfix":
			priority = max(priority, 7)
		}
	}

	// Boost priority for urgent keywords in title
	titleLower := strings.ToLower(title)
	if strings.Contains(titleLower, "urgent") || strings.Contains(titleLower, "critical") ||
	   strings.Contains(titleLower, "hotfix") || strings.Contains(titleLower, "security") {
		priority = max(priority, 8)
	}

	return priority
}

// calculateComplexity estimates task complexity from labels and content
func (g *GiteaProvider) calculateComplexity(labels []string, title, body string) int {
	complexity := 3 // default

	for _, label := range labels {
		switch strings.ToLower(label) {
		case "complexity:high", "epic", "major":
			complexity = 8
		case "complexity:medium":
			complexity = 5
		case "complexity:low", "simple", "trivial":
			complexity = 2
		case "refactor", "architecture":
			complexity = max(complexity, 7)
		case "bug", "hotfix":
			complexity = max(complexity, 4)
		case "enhancement", "feature":
			complexity = max(complexity, 5)
		}
	}

	// Estimate complexity from body length
	bodyLength := len(strings.Fields(body))
	if bodyLength > 200 {
		complexity = max(complexity, 6)
	} else if bodyLength > 50 {
		complexity = max(complexity, 4)
	}

	return complexity
}

// determineRequiredRole determines what agent role is needed for this task
func (g *GiteaProvider) determineRequiredRole(labels []string) string {
	for _, label := range labels {
		switch strings.ToLower(label) {
		case "frontend", "ui", "ux", "css", "html", "javascript", "react", "vue":
			return "frontend-developer"
		case "backend", "api", "server", "database", "sql":
			return "backend-developer"
		case "devops", "infrastructure", "deployment", "docker", "kubernetes":
			return "devops-engineer"
		case "security", "authentication", "authorization":
			return "security-engineer"
		case "testing", "qa", "quality":
			return "tester"
		case "documentation", "docs":
			return "technical-writer"
		case "design", "mockup", "wireframe":
			return "designer"
		}
	}

	return "developer" // default role
}

// determineRequiredExpertise determines what expertise is needed
func (g *GiteaProvider) determineRequiredExpertise(labels []string) []string {
	expertise := make([]string, 0)
	expertiseMap := make(map[string]bool) // prevent duplicates

	for _, label := range labels {
		labelLower := strings.ToLower(label)

		// Programming languages
		languages := []string{"go", "python", "javascript", "typescript", "java", "rust", "c++", "php"}
		for _, lang := range languages {
			if strings.Contains(labelLower, lang) {
				if !expertiseMap[lang] {
					expertise = append(expertise, lang)
					expertiseMap[lang] = true
				}
			}
		}

		// Technologies and frameworks
		technologies := []string{"docker", "kubernetes", "react", "vue", "angular", "nodejs", "django", "flask", "spring"}
		for _, tech := range technologies {
			if strings.Contains(labelLower, tech) {
				if !expertiseMap[tech] {
					expertise = append(expertise, tech)
					expertiseMap[tech] = true
				}
			}
		}

		// Domain areas
		domains := []string{"frontend", "backend", "database", "security", "testing", "devops", "api"}
		for _, domain := range domains {
			if strings.Contains(labelLower, domain) {
				if !expertiseMap[domain] {
					expertise = append(expertise, domain)
					expertiseMap[domain] = true
				}
			}
		}
	}

	// Default expertise if none detected
	if len(expertise) == 0 {
		expertise = []string{"development", "programming"}
	}

	return expertise
}

// addLabelToIssue adds a label to an issue
func (g *GiteaProvider) addLabelToIssue(issueNumber int, labelName string) error {
	endpoint := fmt.Sprintf("/repos/%s/%s/issues/%d/labels", g.owner, g.repo, issueNumber)

	body := map[string]interface{}{
		"labels": []string{labelName},
	}

	resp, err := g.makeRequest("POST", endpoint, body)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusCreated {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("failed to add label (status %d): %s", resp.StatusCode, string(respBody))
	}

	return nil
}

// removeLabelFromIssue removes a label from an issue
func (g *GiteaProvider) removeLabelFromIssue(issueNumber int, labelName string) error {
	endpoint := fmt.Sprintf("/repos/%s/%s/issues/%d/labels/%s", g.owner, g.repo, issueNumber, url.QueryEscape(labelName))

	resp, err := g.makeRequest("DELETE", endpoint, nil)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("failed to remove label (status %d): %s", resp.StatusCode, string(respBody))
	}

	return nil
}

// addCommentToIssue adds a comment to an issue
func (g *GiteaProvider) addCommentToIssue(issueNumber int, comment string) error {
	endpoint := fmt.Sprintf("/repos/%s/%s/issues/%d/comments", g.owner, g.repo, issueNumber)

	body := map[string]interface{}{
		"body": comment,
	}

	resp, err := g.makeRequest("POST", endpoint, body)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusCreated {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("failed to add comment (status %d): %s", resp.StatusCode, string(respBody))
	}

	return nil
}

// closeIssue closes an issue
func (g *GiteaProvider) closeIssue(issueNumber int) error {
	endpoint := fmt.Sprintf("/repos/%s/%s/issues/%d", g.owner, g.repo, issueNumber)

	body := map[string]interface{}{
		"state": "closed",
	}

	resp, err := g.makeRequest("PATCH", endpoint, body)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusCreated && resp.StatusCode != http.StatusOK {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("failed to close issue (status %d): %s", resp.StatusCode, string(respBody))
	}

	return nil
}

// max returns the maximum of two integers
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}