package providers

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

	"chorus/pkg/repository"
)

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

// NewGitHubProvider creates a new GitHub provider
func NewGitHubProvider(config *repository.Config) (*GitHubProvider, error) {
	if config.AccessToken == "" {
		return nil, fmt.Errorf("access token is required for GitHub provider")
	}
	if config.Owner == "" {
		return nil, fmt.Errorf("owner is required for GitHub provider")
	}
	if config.Repository == "" {
		return nil, fmt.Errorf("repository name is required for GitHub provider")
	}

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

// GitHubIssue represents a GitHub issue
type GitHubIssue struct {
	ID          int64         `json:"id"`
	Number      int           `json:"number"`
	Title       string        `json:"title"`
	Body        string        `json:"body"`
	State       string        `json:"state"`
	Labels      []GitHubLabel `json:"labels"`
	CreatedAt   time.Time     `json:"created_at"`
	UpdatedAt   time.Time     `json:"updated_at"`
	Repository  *GitHubRepository `json:"repository,omitempty"`
	Assignee    *GitHubUser   `json:"assignee"`
	Assignees   []GitHubUser  `json:"assignees"`
	User        *GitHubUser   `json:"user"`
	PullRequest *GitHubPullRequestRef `json:"pull_request,omitempty"`
}

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

// GitHubRepository represents a GitHub repository
type GitHubRepository struct {
	ID       int64       `json:"id"`
	Name     string      `json:"name"`
	FullName string      `json:"full_name"`
	Owner    *GitHubUser `json:"owner"`
}

// GitHubUser represents a GitHub user
type GitHubUser struct {
	ID        int64  `json:"id"`
	Login     string `json:"login"`
	Name      string `json:"name"`
	Email     string `json:"email"`
	AvatarURL string `json:"avatar_url"`
}

// GitHubPullRequestRef indicates if issue is a PR
type GitHubPullRequestRef struct {
	URL string `json:"url"`
}

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

// makeRequest makes an HTTP request to the GitHub API
func (g *GitHubProvider) 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("https://api.github.com%s", 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/vnd.github.v3+json")
	req.Header.Set("User-Agent", "CHORUS-Agent/1.0")

	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 GitHub repository
func (g *GitHubProvider) GetTasks(projectID int) ([]*repository.Task, error) {
	// Build query parameters
	params := url.Values{}
	params.Add("state", "open")
	params.Add("sort", "created")
	params.Add("direction", "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 []GitHubIssue
	if err := json.NewDecoder(resp.Body).Decode(&issues); err != nil {
		return nil, fmt.Errorf("failed to decode issues: %w", err)
	}

	// Filter out pull requests (GitHub API includes PRs in issues endpoint)
	tasks := make([]*repository.Task, 0, len(issues))
	for _, issue := range issues {
		// Skip pull requests
		if issue.PullRequest != nil {
			continue
		}

		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 *GitHubProvider) 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 GitHubIssue
	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 || len(issue.Assignees) > 0 {
		assigneeName := ""
		if issue.Assignee != nil {
			assigneeName = issue.Assignee.Login
		} else if len(issue.Assignees) > 0 {
			assigneeName = issue.Assignees[0].Login
		}
		return false, fmt.Errorf("issue is already assigned to %s", assigneeName)
	}

	// 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**\n\nAgent ID: `%s`\nStatus: Processing\n\nThis task is now being handled automatically by the CHORUS autonomous agent system.", 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 *GitHubProvider) 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\n\n---\n*Updated by CHORUS Agent*", 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 *GitHubProvider) CompleteTask(task *repository.Task, result *repository.TaskResult) error {
	// Create completion comment with results
	var commentBuffer strings.Builder
	commentBuffer.WriteString("✅ **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\n")
		for key, value := range result.Metadata {
			// Format the metadata nicely
			switch key {
			case "duration":
				commentBuffer.WriteString(fmt.Sprintf("- ⏱️ **Duration:** %v\n", value))
			case "execution_type":
				commentBuffer.WriteString(fmt.Sprintf("- 🔧 **Execution Type:** %v\n", value))
			case "commands_executed":
				commentBuffer.WriteString(fmt.Sprintf("- 🖥️ **Commands Executed:** %v\n", value))
			case "files_generated":
				commentBuffer.WriteString(fmt.Sprintf("- 📄 **Files Generated:** %v\n", value))
			case "ai_provider":
				commentBuffer.WriteString(fmt.Sprintf("- 🤖 **AI Provider:** %v\n", value))
			case "ai_model":
				commentBuffer.WriteString(fmt.Sprintf("- 🧠 **AI Model:** %v\n", value))
			default:
				commentBuffer.WriteString(fmt.Sprintf("- **%s:** %v\n", key, value))
			}
		}
		commentBuffer.WriteString("\n")
	}

	commentBuffer.WriteString("---\n🤖 *Completed by CHORUS Autonomous Agent System*")

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

	// Skip pull requests
	if issue.PullRequest != nil {
		return nil, fmt.Errorf("pull requests are not supported as tasks")
	}

	return g.issueToTask(&issue), nil
}

// ListAvailableTasks lists all available (unassigned) tasks
func (g *GitHubProvider) ListAvailableTasks(projectID int) ([]*repository.Task, error) {
	// GitHub doesn't have a direct "unassigned" filter, so we get open issues and filter
	params := url.Values{}
	params.Add("state", "open")
	params.Add("sort", "created")
	params.Add("direction", "desc")

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

	// Filter out assigned issues and PRs
	tasks := make([]*repository.Task, 0, len(issues))
	for _, issue := range issues {
		// Skip pull requests
		if issue.PullRequest != nil {
			continue
		}

		// 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 GitHub issue to a repository Task
func (g *GitHubProvider) issueToTask(issue *GitHubIssue) *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{}{
			"github_id":    issue.ID,
			"provider":     "github",
			"repository":   issue.Repository,
			"assignee":     issue.Assignee,
			"assignees":    issue.Assignees,
			"user":         issue.User,
		},
	}
}

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

	for _, label := range labels {
		labelLower := strings.ToLower(label)
		switch {
		case strings.Contains(labelLower, "priority") && strings.Contains(labelLower, "critical"):
			priority = 10
		case strings.Contains(labelLower, "priority") && strings.Contains(labelLower, "high"):
			priority = 8
		case strings.Contains(labelLower, "priority") && strings.Contains(labelLower, "medium"):
			priority = 5
		case strings.Contains(labelLower, "priority") && strings.Contains(labelLower, "low"):
			priority = 2
		case labelLower == "critical" || labelLower == "urgent":
			priority = 10
		case labelLower == "high":
			priority = 8
		case labelLower == "bug" || labelLower == "security" || labelLower == "hotfix":
			priority = max(priority, 7)
		case labelLower == "enhancement" || labelLower == "feature":
			priority = max(priority, 5)
		case labelLower == "good first issue":
			priority = max(priority, 3)
		}
	}

	// Boost priority for urgent keywords in title
	titleLower := strings.ToLower(title)
	urgentKeywords := []string{"urgent", "critical", "hotfix", "security", "broken", "crash"}
	for _, keyword := range urgentKeywords {
		if strings.Contains(titleLower, keyword) {
			priority = max(priority, 8)
			break
		}
	}

	return priority
}

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

	for _, label := range labels {
		labelLower := strings.ToLower(label)
		switch {
		case strings.Contains(labelLower, "complexity") && strings.Contains(labelLower, "high"):
			complexity = 8
		case strings.Contains(labelLower, "complexity") && strings.Contains(labelLower, "medium"):
			complexity = 5
		case strings.Contains(labelLower, "complexity") && strings.Contains(labelLower, "low"):
			complexity = 2
		case labelLower == "epic" || labelLower == "major":
			complexity = 8
		case labelLower == "refactor" || labelLower == "architecture":
			complexity = max(complexity, 7)
		case labelLower == "bug" || labelLower == "hotfix":
			complexity = max(complexity, 4)
		case labelLower == "enhancement" || labelLower == "feature":
			complexity = max(complexity, 5)
		case labelLower == "good first issue" || labelLower == "beginner":
			complexity = 2
		case labelLower == "documentation" || labelLower == "docs":
			complexity = max(complexity, 3)
		}
	}

	// Estimate complexity from body length and content
	bodyLength := len(strings.Fields(body))
	if bodyLength > 500 {
		complexity = max(complexity, 7)
	} else if bodyLength > 200 {
		complexity = max(complexity, 5)
	} else if bodyLength > 50 {
		complexity = max(complexity, 4)
	}

	// Look for complexity indicators in content
	bodyLower := strings.ToLower(body)
	complexityIndicators := []string{"refactor", "architecture", "breaking change", "migration", "redesign"}
	for _, indicator := range complexityIndicators {
		if strings.Contains(bodyLower, indicator) {
			complexity = max(complexity, 7)
			break
		}
	}

	return complexity
}

// determineRequiredRole determines what agent role is needed for this task
func (g *GitHubProvider) determineRequiredRole(labels []string) string {
	roleKeywords := map[string]string{
		// Frontend
		"frontend": "frontend-developer",
		"ui":       "frontend-developer",
		"ux":       "ui-ux-designer",
		"css":      "frontend-developer",
		"html":     "frontend-developer",
		"javascript": "frontend-developer",
		"react":    "frontend-developer",
		"vue":      "frontend-developer",
		"angular":  "frontend-developer",

		// Backend
		"backend":  "backend-developer",
		"api":      "backend-developer",
		"server":   "backend-developer",
		"database": "backend-developer",
		"sql":      "backend-developer",

		// DevOps
		"devops":       "devops-engineer",
		"infrastructure": "devops-engineer",
		"deployment":   "devops-engineer",
		"docker":       "devops-engineer",
		"kubernetes":   "devops-engineer",
		"ci/cd":        "devops-engineer",

		// Security
		"security":       "security-engineer",
		"authentication": "security-engineer",
		"authorization":  "security-engineer",
		"vulnerability":  "security-engineer",

		// Testing
		"testing": "tester",
		"qa":      "tester",
		"test":    "tester",

		// Documentation
		"documentation": "technical-writer",
		"docs":          "technical-writer",

		// Design
		"design":    "ui-ux-designer",
		"mockup":    "ui-ux-designer",
		"wireframe": "ui-ux-designer",
	}

	for _, label := range labels {
		labelLower := strings.ToLower(label)
		for keyword, role := range roleKeywords {
			if strings.Contains(labelLower, keyword) {
				return role
			}
		}
	}

	return "developer" // default role
}

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

	expertiseKeywords := map[string][]string{
		// Programming languages
		"go":         {"go", "golang"},
		"python":     {"python"},
		"javascript": {"javascript", "js"},
		"typescript": {"typescript", "ts"},
		"java":       {"java"},
		"rust":       {"rust"},
		"c++":        {"c++", "cpp"},
		"c#":         {"c#", "csharp"},
		"php":        {"php"},
		"ruby":       {"ruby"},

		// Frontend technologies
		"react":   {"react"},
		"vue":     {"vue", "vuejs"},
		"angular": {"angular"},
		"svelte":  {"svelte"},

		// Backend frameworks
		"nodejs":  {"nodejs", "node.js", "node"},
		"django":  {"django"},
		"flask":   {"flask"},
		"spring":  {"spring"},
		"express": {"express"},

		// Databases
		"postgresql": {"postgresql", "postgres"},
		"mysql":      {"mysql"},
		"mongodb":    {"mongodb", "mongo"},
		"redis":      {"redis"},

		// DevOps tools
		"docker":     {"docker"},
		"kubernetes": {"kubernetes", "k8s"},
		"aws":        {"aws"},
		"azure":      {"azure"},
		"gcp":        {"gcp", "google cloud"},

		// Other technologies
		"graphql": {"graphql"},
		"rest":    {"rest", "restful"},
		"grpc":    {"grpc"},
	}

	for _, label := range labels {
		labelLower := strings.ToLower(label)
		for expertiseArea, keywords := range expertiseKeywords {
			for _, keyword := range keywords {
				if strings.Contains(labelLower, keyword) && !expertiseMap[expertiseArea] {
					expertise = append(expertise, expertiseArea)
					expertiseMap[expertiseArea] = true
					break
				}
			}
		}
	}

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

	return expertise
}

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

	body := []string{labelName}

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

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

	return nil
}