package fastcgi

import (
	"bufio"
	"bytes"
	"encoding/binary"
	"io"
	"net/http"
	"net/http/httputil"
	"net/textproto"
	"strconv"
	"strings"
	"sync"
)

type FCGIClient struct {
	mutex     sync.Mutex
	rwc       io.ReadWriteCloser
	h         Header
	buf       bytes.Buffer
	keepAlive bool
	reqId     uint16
}

// Close fcgi connnection
func (client *FCGIClient) Close() {
	client.rwc.Close()
}

func (client *FCGIClient) writeRecord(recType FCGIRequestType, content []byte) (err error) {
	client.mutex.Lock()
	defer client.mutex.Unlock()
	client.buf.Reset()
	// Initialize the record
	header := Header{}
	header.init(recType, 1, len(content))
	rec := Record{
		Header:  header,
		Content: content,
	}

	// Write the record to the connection
	b, err := rec.toBytes()
	_, err = client.rwc.Write(b)
	return err
}

func (client *FCGIClient) writeEndRequest(appStatus int, protocolStatus uint8) error {
	b := make([]byte, 8)
	binary.BigEndian.PutUint32(b, uint32(appStatus))
	b[4] = protocolStatus
	return client.writeRecord(FCGI_END_REQUEST, b)
}

func (client *FCGIClient) writePairs(recType FCGIRequestType, pairs map[string]string) error {
	w := newWriter(client, recType)
	b := make([]byte, 8)
	nn := 0
	for k, v := range pairs {
		m := 8 + len(k) + len(v)
		if m > maxWrite {
			// param data size exceed 65535 bytes"
			vl := maxWrite - 8 - len(k)
			v = v[:vl]
		}
		n := encodeSize(b, uint32(len(k)))
		n += encodeSize(b[n:], uint32(len(v)))
		m = n + len(k) + len(v)
		if (nn + m) > maxWrite {
			w.Flush()
			nn = 0
		}
		nn += m
		if _, err := w.Write(b[:n]); err != nil {
			return err
		}
		if _, err := w.WriteString(k); err != nil {
			return err
		}
		if _, err := w.WriteString(v); err != nil {
			return err
		}
	}
	w.Close()
	return nil
}

// Do made the request and returns a io.Reader that translates the data read
// from fcgi responder out of fcgi packet before returning it.
func (client *FCGIClient) Do(req *FCGIRequest) (http.Response, error) {
	beginRequestRecord := NewBeginRequestRecord()
	err := client.writeRecord(beginRequestRecord.Header.Type, beginRequestRecord.Content)
	if err != nil {
		return http.Response{}, err
	}

	err = client.writePairs(FCGI_PARAMS, req.Context)
	if err != nil {
		return http.Response{}, err
	}

	// body := newWriter(client, FCGI_STDIN)
	// if req != nil {
	// 	io.Copy(body, req)
	// }
	// body.Close()

	r := &streamReader{c: client}
	rb := bufio.NewReader(r)
	tp := textproto.NewReader(rb)
	resp := new(http.Response)
	// Parse the first line of the response.
	line, err := tp.ReadLine()
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return http.Response{}, err
	}
	if i := strings.IndexByte(line, ' '); i == -1 {
		err = &badStringError{"malformed HTTP response", line}
	} else {
		resp.Proto = line[:i]
		resp.Status = strings.TrimLeft(line[i+1:], " ")
	}
	statusCode := resp.Status
	if i := strings.IndexByte(resp.Status, ' '); i != -1 {
		statusCode = resp.Status[:i]
	}
	if len(statusCode) != 3 {
		err = &badStringError{"malformed HTTP status code", statusCode}
	}
	resp.StatusCode, err = strconv.Atoi(statusCode)
	if err != nil || resp.StatusCode < 0 {
		err = &badStringError{"malformed HTTP status code", statusCode}
	}
	var ok bool
	if resp.ProtoMajor, resp.ProtoMinor, ok = http.ParseHTTPVersion(resp.Proto); !ok {
		err = &badStringError{"malformed HTTP version", resp.Proto}
	}
	// Parse the response headers.
	mimeHeader, err := tp.ReadMIMEHeader()
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return http.Response{}, err
	}
	resp.Header = http.Header(mimeHeader)
	// TODO: fixTransferEncoding ?
	resp.TransferEncoding = resp.Header["Transfer-Encoding"]
	resp.ContentLength, _ = strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64)

	if chunked(resp.TransferEncoding) {
		resp.Body = io.NopCloser(httputil.NewChunkedReader(rb))
	} else {
		resp.Body = io.NopCloser(rb)
	}

	return *resp, nil
}