package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"sync"
	"time"

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

// GitLabPayload 简化版的 GitLab Push Webhook 数据结构
type GitLabPayload struct {
	Ref     string `json:"ref"`
	After   string `json:"after"`
	Project struct {
		PathWithNamespace string `json:"path_with_namespace"`
	} `json:"project"`
}

// debounceEntry 单个 key 的冷却去重状态。
// lastExec：上次实际执行时刻；冷却窗口内到达的 push 直接丢弃，无补跑。
type debounceEntry struct {
	mu       sync.Mutex
	lastExec time.Time
}

func handleWebhook(c *gin.Context) {
	// 1. 校验 GitLab Secret Token Header
	clientToken := c.GetHeader("X-Gitlab-Token")
	if globalConfig.SecretToken != "" && clientToken != globalConfig.SecretToken {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid Secret Token"})
		return
	}

	// 2. 校验 Event 类型
	eventType := c.GetHeader("X-Gitlab-Event")
	if eventType != "Push Hook" {
		c.JSON(http.StatusOK, gin.H{"status": "ignored", "reason": "Only Push Hook is handled"})
		return
	}

	// 3. 解析 Body JSON
	var payload GitLabPayload
	if err := c.ShouldBindJSON(&payload); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid JSON Payload"})
		return
	}

	repoName := payload.Project.PathWithNamespace
	ref := payload.Ref
	commitID := payload.After

	if repoName == "" || ref == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Missing repo or ref in payload"})
		return
	}

	// 4. 匹配脚本路径
	repoConfig, exists := globalConfig.Projects[repoName]
	if !exists {
		c.JSON(http.StatusOK, gin.H{"status": "ignored", "message": "No script config for repository " + repoName})
		return
	}

	scriptPath, exists := repoConfig[ref]
	if !exists {
		c.JSON(http.StatusOK, gin.H{"status": "ignored", "message": fmt.Sprintf("No script config for %s on %s", repoName, ref)})
		return
	}

	// 5. 校验脚本文件是否存在
	if _, err := os.Stat(scriptPath); os.IsNotExist(err) {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Script file not found: " + scriptPath})
		return
	}

	// 6. 冷却去重：窗口外 push 立即执行并刷新 lastExec，窗口内 push 直接丢弃
	lockKey := fmt.Sprintf("%s:%s", repoName, ref)
	entryVal, _ := lastExecMap.LoadOrStore(lockKey, &debounceEntry{})
	entry := entryVal.(*debounceEntry)

	entry.mu.Lock()
	now := time.Now()

	if !entry.lastExec.IsZero() && now.Sub(entry.lastExec) < debounceDuration {
		remainingSeconds := max(int((debounceDuration - now.Sub(entry.lastExec)).Seconds()), 0)
		entry.mu.Unlock()

		msg := fmt.Sprintf("3 分钟内频繁提交被拦截, 剩余冷却时间: %d 秒", remainingSeconds)
		log.Printf("[DEBOUNCE] 跳过执行 [%s] %s\n", lockKey, msg)
		c.JSON(http.StatusOK, gin.H{
			"status":            "debounced",
			"message":           msg,
			"remaining_seconds": remainingSeconds,
		})
		return
	}

	entry.lastExec = now
	entry.mu.Unlock()

	log.Printf("[INFO] 开始执行脚本: %s (仓库: %s, 分支: %s, commit: %s)\n",
		scriptPath, repoName, ref, shortCommit(commitID))
	go runScript(scriptPath, repoName, ref, commitID)

	c.JSON(http.StatusOK, gin.H{
		"status":     "triggered",
		"repository": repoName,
		"ref":        ref,
		"script":     scriptPath,
	})
}