package gemini

import (
	"bufio"
	"crypto/tls"
	"io"
	"net/url"
)

// A Request represents a Gemini request received by a server or to be sent
// by a client.
type Request struct {
	// URL specifies the URL being requested.
	URL *url.URL

	// For client requests, Host optionally specifies the server to
	// connect to. It may be of the form "host" or "host:port".
	// If empty, the value of URL.Host is used.
	// For international domain names, Host may be in Punycode or
	// Unicode form. Use golang.org/x/net/idna to convert it to
	// either format if needed.
	// This field is ignored by the Gemini server.
	Host string

	// For client requests, Certificate optionally specifies the
	// TLS certificate to present to the other side of the connection.
	// This field is ignored by the Gemini server.
	Certificate *tls.Certificate

	TLS *tls.ConnectionState
}

// NewRequest returns a new request.
// The returned Request is suitable for use with Client.Do.
//
// Callers should be careful that the URL query is properly escaped.
// See the documentation for QueryEscape for more information.
func NewRequest(rawurl string) (*Request, error) {
	u, err := url.Parse(rawurl)
	if err != nil {
		return nil, err
	}
	return &Request{URL: u}, nil
}

// ReadRequest reads and parses an incoming request from r.
//
// ReadRequest is a low-level function and should only be used
// for specialized applications; most code should use the Server
// to read requests and handle them via the Handler interface.
func ReadRequest(r io.Reader) (*Request, error) {
	// Limit request size
	r = io.LimitReader(r, 1026)
	br := bufio.NewReaderSize(r, 1026)
	b, err := br.ReadBytes('\n')
	if err != nil {
		if err == io.EOF {
			return nil, ErrInvalidRequest
		}
		return nil, err
	}
	// Read URL
	rawurl, ok := trimCRLF(b)
	if !ok {
		return nil, ErrInvalidRequest
	}
	if len(rawurl) == 0 {
		return nil, ErrInvalidRequest
	}
	u, err := url.Parse(string(rawurl))
	if err != nil {
		return nil, err
	}
	return &Request{URL: u}, nil
}

// WriteTo writes r to w in the Gemini request format.
// This method consults the request URL only.
func (r *Request) WriteTo(w io.Writer) (int64, error) {
	bw := bufio.NewWriterSize(w, 1026)
	url := r.URL.String()
	if len(url) > 1024 {
		return 0, ErrInvalidRequest
	}
	var wrote int64
	n, err := bw.WriteString(url)
	wrote += int64(n)
	if err != nil {
		return wrote, err
	}
	n, err = bw.Write(crlf)
	wrote += int64(n)
	if err != nil {
		return wrote, err
	}
	return wrote, bw.Flush()
}

// ServerName returns the value of the TLS Server Name Indication extension
// sent by the client.
// ServerName returns an empty string for client requests.
func (r *Request) ServerName() string {
	if tls := r.TLS; tls != nil {
		return tls.ServerName
	}
	return ""
}