package handlers

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"io"
	"net/http"
	"strconv"
	"strings"

	"giteapm/internal/models"

	"github.com/gin-gonic/gin"
)

type GiteaWebhookPayload struct {
	Action     string `json:"action"`
	Number     int    `json:"number"`
	Repository struct {
		ID       int    `json:"id"`
		Name     string `json:"name"`
		FullName string `json:"full_name"`
	} `json:"repository"`
	PullRequest *struct {
		ID     int    `json:"id"`
		Number int    `json:"number"`
		Title  string `json:"title"`
		State  string `json:"state"`
		HTMLURL string `json:"html_url"`
	} `json:"pull_request,omitempty"`
	Commits []struct {
		ID      string `json:"id"`
		Message string `json:"message"`
		URL     string `json:"url"`
	} `json:"commits,omitempty"`
	Pusher struct {
		ID       int    `json:"id"`
		Username string `json:"username"`
	} `json:"pusher,omitempty"`
}

func (h *Handlers) HandleGiteaWebhook(c *gin.Context) {
	// 验证 webhook 签名
	if !h.verifyWebhookSignature(c) {
		c.JSON(http.StatusUnauthorized, ErrorResponse(401, "Invalid webhook signature"))
		return
	}

	// 读取请求体
	body, err := io.ReadAll(c.Request.Body)
	if err != nil {
		c.JSON(http.StatusBadRequest, ErrorResponse(400, "Failed to read request body"))
		return
	}

	// 解析 payload
	var payload GiteaWebhookPayload
	if err := json.Unmarshal(body, &payload); err != nil {
		c.JSON(http.StatusBadRequest, ErrorResponse(400, "Invalid JSON payload"))
		return
	}

	// 获取事件类型
	eventType := c.GetHeader("X-Gitea-Event")
	
	// 处理不同类型的事件
	switch eventType {
	case "push":
		h.handlePushEvent(payload)
	case "pull_request":
		h.handlePullRequestEvent(payload)
	case "issues":
		h.handleIssueEvent(payload)
	default:
		// 忽略其他事件类型
	}

	c.JSON(http.StatusOK, SuccessResponse(gin.H{"message": "Webhook processed successfully"}))
}

func (h *Handlers) verifyWebhookSignature(c *gin.Context) bool {
	signature := c.GetHeader("X-Gitea-Signature")
	if signature == "" {
		return false
	}

	// 读取请求体
	body, err := io.ReadAll(c.Request.Body)
	if err != nil {
		return false
	}

	// 重新设置请求体，以便后续读取
	c.Request.Body = io.NopCloser(strings.NewReader(string(body)))

	// 计算 HMAC-SHA256
	mac := hmac.New(sha256.New, []byte(h.Cfg.Gitea.WebhookSecret))
	mac.Write(body)
	expectedSignature := hex.EncodeToString(mac.Sum(nil))

	// 比较签名
	return hmac.Equal([]byte(signature), []byte(expectedSignature))
}

func (h *Handlers) handlePushEvent(payload GiteaWebhookPayload) {
	// 处理推送事件
	repoID := uint(payload.Repository.ID)
	
	for _, commit := range payload.Commits {
		// 查找关联的任务
		_, err := models.GetGiteaRelationsByRepo(repoID, "commit")
		if err != nil {
			continue
		}

		// 检查提交消息中是否包含任务引用（如 #123）
		commitMessage := commit.Message
		taskNumbers := extractTaskNumbers(commitMessage)

		for _, taskNumber := range taskNumbers {
			// 创建或更新 Git 关联
			relation := &models.GiteaRelation{
				GiteaRepoID:       repoID,
				GiteaRepoName:     payload.Repository.FullName,
				RelationType:      "commit",
				GiteaObjectID:     commit.ID,
				GiteaObjectTitle:  commitMessage,
				GiteaObjectURL:    commit.URL,
			}

			// 根据任务号查找任务
			if task := findTaskByNumber(taskNumber); task != nil {
				relation.TaskID = task.ID
				models.CreateGiteaRelation(relation)

				// 可以根据提交消息自动更新任务状态
				if strings.Contains(strings.ToLower(commitMessage), "fix") ||
				   strings.Contains(strings.ToLower(commitMessage), "resolve") {
					task.Status = "review"
					models.UpdateTask(task)
				}
			}
		}
	}
}

func (h *Handlers) handlePullRequestEvent(payload GiteaWebhookPayload) {
	if payload.PullRequest == nil {
		return
	}

	pr := payload.PullRequest
	repoID := uint(payload.Repository.ID)

	// 检查 PR 标题中的任务引用
	taskNumbers := extractTaskNumbers(pr.Title)

	for _, taskNumber := range taskNumbers {
		if task := findTaskByNumber(taskNumber); task != nil {
			relation := &models.GiteaRelation{
				TaskID:            task.ID,
				GiteaRepoID:       repoID,
				GiteaRepoName:     payload.Repository.FullName,
				RelationType:      "pull_request",
				GiteaObjectID:     strconv.Itoa(pr.ID),
				GiteaObjectNumber: func() *uint { n := uint(pr.Number); return &n }(),
				GiteaObjectTitle:  pr.Title,
				GiteaObjectURL:    pr.HTMLURL,
			}

			models.CreateGiteaRelation(relation)

			// 根据 PR 状态自动更新任务状态
			switch payload.Action {
			case "opened":
				task.Status = "review"
			case "closed":
				if pr.State == "merged" {
					task.Status = "done"
				}
			}
			models.UpdateTask(task)
		}
	}
}

func (h *Handlers) handleIssueEvent(payload GiteaWebhookPayload) {
	// 处理 Issue 事件，可以将 Gitea Issue 同步为任务
	// 这里可以根据需要实现
}

// 从文本中提取任务编号（如 #123, fixes #456）
func extractTaskNumbers(text string) []int {
	var numbers []int
	// 简单的正则匹配，实际可以使用更复杂的逻辑
	words := strings.Fields(text)
	for _, word := range words {
		if strings.HasPrefix(word, "#") {
			if num, err := strconv.Atoi(strings.TrimPrefix(word, "#")); err == nil {
				numbers = append(numbers, num)
			}
		}
	}
	return numbers
}

// 根据任务编号查找任务（这里简化实现）
func findTaskByNumber(taskNumber int) *models.Task {
	// 这里应该实现根据任务编号查找任务的逻辑
	// 可以在数据库中添加 task_number 字段，或者使用 ID
	task, err := models.GetTaskByID(uint(taskNumber))
	if err != nil {
		return nil
	}
	return task
}