package middleware

import (
	"net/http"
	"os"
	"strings"
	"sync"

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

var (
	maintenanceMode     bool
	maintenanceModeOnce sync.Once
	maintenanceMu       sync.RWMutex
)

func init() {
	maintenanceModeOnce.Do(func() {
		v := os.Getenv("MAINTENANCE_MODE")
		maintenanceMode = v == "true" || v == "1"
	})
}

// MaintenanceModeEnabled returns whether maintenance mode is active
func MaintenanceModeEnabled() bool {
	maintenanceMu.RLock()
	defer maintenanceMu.RUnlock()
	return maintenanceMode
}

// SetMaintenanceMode sets maintenance mode (for admin toggle)
func SetMaintenanceMode(enabled bool) {
	maintenanceMu.Lock()
	defer maintenanceMu.Unlock()
	maintenanceMode = enabled
}

// MaintenanceGin returns a Gin middleware for maintenance mode.
// Exempt paths: /health, /healthz, /readyz, /api/v1/health, /api/v1/admin, /swagger, /docs
func MaintenanceGin() gin.HandlerFunc {
	return func(c *gin.Context) {
		if !MaintenanceModeEnabled() {
			c.Next()
			return
		}
		path := c.Request.URL.Path
		if isMaintenanceExempt(path) {
			c.Next()
			return
		}
		c.AbortWithStatusJSON(http.StatusServiceUnavailable, gin.H{"error": "Platform is under maintenance"})
	}
}

func isMaintenanceExempt(path string) bool {
	path = strings.TrimSuffix(path, "/")
	exempts := []string{"/health", "/healthz", "/readyz", "/health/deep", "/metrics", "/swagger", "/docs", "/api/versions"}
	for _, exempt := range exempts {
		if path == exempt || strings.HasPrefix(path, exempt+"/") {
			return true
		}
	}
	if strings.Contains(path, "/api/v1/health") {
		return true
	}
	if strings.Contains(path, "/api/v1/admin") {
		return true
	}
	return false
}