package middleware

import (
	"github.com/gin-gonic/gin"

	"streambox/config"
)

func Cors(cfg config.CorsConfig) gin.HandlerFunc {
	return func(c *gin.Context) {
		origin := c.GetHeader("Origin")
		allowed := false
		for _, o := range cfg.AllowOrigins {
			if o == "*" || o == origin {
				allowed = true
				break
			}
		}
		if allowed {
			if len(cfg.AllowOrigins) == 1 && cfg.AllowOrigins[0] == "*" {
				c.Header("Access-Control-Allow-Origin", "*")
			} else if origin != "" {
				c.Header("Access-Control-Allow-Origin", origin)
			}
			c.Header("Vary", "Origin")
		}
		c.Header("Access-Control-Allow-Credentials", "true")
		if len(cfg.AllowMethods) > 0 {
			c.Header("Access-Control-Allow-Methods", join(cfg.AllowMethods))
		}
		if len(cfg.AllowHeaders) > 0 {
			c.Header("Access-Control-Allow-Headers", join(cfg.AllowHeaders))
		}
		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(204)
			return
		}
		c.Next()
	}
}

func join(a []string) string {
	s := ""
	for i, v := range a {
		if i > 0 {
			s += ", "
		}
		s += v
	}
	return s
}