package server

import (
	"fmt"
	"net"
	"os"

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

// Option functions set unexported private fields in the ServerConfig.
// Use it to set things like the storage backend and port.
type Option func(*Config) error

func validPortNumber(port int) error {
	if port <= 0 || port > 65535 {
		return fmt.Errorf("Invalid port number %q", port)
	}
	return nil
}

// OptionPort sets the port to listen on. Omitting the ServerOptionPort causes the server to use port 80.
func OptionPort(port int) Option {
	return func(cfg *Config) error {
		cfg.port = port
		return validPortNumber(port)
	}
}

// OptionHandler serves the gin handler on the provided path.
func OptionHandler(path string, handler gin.HandlerFunc) Option {
	return func(c *Config) error {
		if handler == nil || path == "" {
			return fmt.Errorf("handler and path must be set")
		}
		if c.handlers == nil {
			c.handlers = make(map[string]Handler)
		}
		if _, taken := c.handlers[path]; taken {
			return fmt.Errorf("handler path %q already registered", path)
		}
		c.handlers[path] = Handler(handler)
		return nil
	}
}

// OptionSecure creates an https server using the provided tls cert and key files.
//
// If the OptionPort is not set, then the `:https` Addr is used.
func OptionSecure(certFile, keyFile string) Option {
	return func(cfg *Config) error {
		var f, err = os.Open(certFile)
		if err != nil {
			return fmt.Errorf("could not open cert file %q because of error: %w", certFile, err)
		}
		f.Close()
		f, err = os.Open(keyFile)
		if err != nil {
			return fmt.Errorf("could not open key file %q because of error: %w", keyFile, err)
		}
		f.Close()

		cfg.secure = true
		cfg.secureCertFile = certFile
		cfg.secureKeyFile = keyFile
		return nil
	}
}

// OptionListener is used to set a custom net.Listener for the server.
// This server option is used in tests because some CICD environments don't allow ports to be opened.
func OptionListener(l net.Listener) Option {
	return func(cfg *Config) error {
		cfg.listener = l
		return nil
	}
}