package router

import (
	"github.com/atlasos/calypso/internal/common/config"
	"github.com/gin-gonic/gin"
)

// securityHeadersMiddleware adds security headers to responses
func securityHeadersMiddleware(cfg *config.Config) gin.HandlerFunc {
	if !cfg.Security.SecurityHeaders.Enabled {
		return func(c *gin.Context) {
			c.Next()
		}
	}

	return func(c *gin.Context) {
		// Prevent clickjacking
		c.Header("X-Frame-Options", "DENY")
		
		// Prevent MIME type sniffing
		c.Header("X-Content-Type-Options", "nosniff")
		
		// Enable XSS protection
		c.Header("X-XSS-Protection", "1; mode=block")
		
		// Strict Transport Security (HSTS) - only if using HTTPS
		// c.Header("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
		
		// Content Security Policy (basic)
		c.Header("Content-Security-Policy", "default-src 'self'")
		
		// Referrer Policy
		c.Header("Referrer-Policy", "strict-origin-when-cross-origin")
		
		// Permissions Policy
		c.Header("Permissions-Policy", "geolocation=(), microphone=(), camera=()")
		
		c.Next()
	}
}

// corsMiddleware creates configurable CORS middleware
func corsMiddleware(cfg *config.Config) gin.HandlerFunc {
	return func(c *gin.Context) {
		origin := c.Request.Header.Get("Origin")
		
		// Check if origin is allowed
		allowed := false
		for _, allowedOrigin := range cfg.Security.CORS.AllowedOrigins {
			if allowedOrigin == "*" || allowedOrigin == origin {
				allowed = true
				break
			}
		}

		if allowed {
			c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
		}

		if cfg.Security.CORS.AllowCredentials {
			c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")
		}

		// Set allowed methods
		methods := cfg.Security.CORS.AllowedMethods
		if len(methods) == 0 {
			methods = []string{"GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"}
		}
		c.Writer.Header().Set("Access-Control-Allow-Methods", joinStrings(methods, ", "))

		// Set allowed headers
		headers := cfg.Security.CORS.AllowedHeaders
		if len(headers) == 0 {
			headers = []string{"Content-Type", "Authorization", "Accept", "Origin"}
		}
		c.Writer.Header().Set("Access-Control-Allow-Headers", joinStrings(headers, ", "))

		// Handle preflight requests
		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(204)
			return
		}

		c.Next()
	}
}

// joinStrings joins a slice of strings with a separator
func joinStrings(strs []string, sep string) string {
	if len(strs) == 0 {
		return ""
	}
	if len(strs) == 1 {
		return strs[0]
	}
	result := strs[0]
	for _, s := range strs[1:] {
		result += sep + s
	}
	return result
}