package httputils

import (
	"crypto/tls"
	"fmt"
	"github.com/lucas-clemente/quic-go"
	"github.com/lucas-clemente/quic-go/http3"
	"github.com/valyala/fasthttp"
	"io"
	"net/http"
	"net/textproto"
	"strconv"
	"strings"
	"time"
)

type NetHTTPContext struct {
	httpWriter   http.ResponseWriter
	httpRequest  *http.Request
	server       *Server
	connTime     time.Time
	requestTime  time.Time
	tlsState     tls.ConnectionState
	timingEvents uint
}

func NewRequestContextFromHttp(server *Server, w http.ResponseWriter, r *http.Request) *NetHTTPContext {
	return &NetHTTPContext{
		httpWriter:  w,
		httpRequest: r,
		connTime:    time.Now(),
		requestTime: time.Now(),
		server:      server,
		tlsState:    getTLSState(w, r),
	}
}

func getTLSState(w http.ResponseWriter, r *http.Request) tls.ConnectionState {
	if hj, ok := w.(http3.Hijacker); ok {
		if conn, ok := hj.StreamCreator().(quic.Connection); ok {
			return conn.ConnectionState().TLS.ConnectionState
		}
	}
	if r.TLS != nil {
		return *r.TLS
	}

	return tls.ConnectionState{}
}

func (c *NetHTTPContext) GetExtraHeaders() map[string]string {
	return c.server.GetExtraHeaders()
}

func (c *NetHTTPContext) AddTiming(name string, desc string, d time.Duration) {
	if d < 0 {
		d = 0
	}

	c.AddResponseHeader("Server-Timing", fmt.Sprintf("%d_%s;desc=\"%s\";dur=%.6F", c.timingEvents, name, desc, float64(d.Nanoseconds())/1e6))
	c.timingEvents++
}

func (c *NetHTTPContext) AddTimingInformational(name string, desc string) {
	c.AddResponseHeader("Server-Timing", fmt.Sprintf("%d_%s;desc=\"%s\"", c.timingEvents, name, desc))
	c.timingEvents++
}

func (c *NetHTTPContext) GetPath() string {
	return c.httpRequest.URL.Path

}

func (c *NetHTTPContext) GetConnectionTime() time.Time {
	return c.connTime
}

func (c *NetHTTPContext) GetRequestTime() time.Time {
	return c.requestTime
}

func (c *NetHTTPContext) GetTLSServerName() string {
	return c.tlsState.ServerName
}

func (c *NetHTTPContext) GetHost() string {
	return c.httpRequest.Host
}

func (c *NetHTTPContext) GetProtocol() string {
	return c.httpRequest.Proto
}

func (c *NetHTTPContext) GetTLSVersion() uint16 {
	return c.tlsState.Version
}

func (c *NetHTTPContext) GetTLSCipher() uint16 {
	return c.tlsState.CipherSuite
}

func (c *NetHTTPContext) GetRequestHeader(name string) string {
	return c.httpRequest.Header.Get(name)

}

func (c *NetHTTPContext) GetResponseHeader(name string) string {
	return c.httpWriter.Header().Get(name)
}

func (c *NetHTTPContext) AddResponseHeader(name string, value string) {
	c.httpWriter.Header().Add(name, value)
}

func (c *NetHTTPContext) SetResponseHeader(name string, value string) {
	c.httpWriter.Header().Set(name, value)
}

func (c *NetHTTPContext) ServeStream(stream Stream) {
	defer stream.Close()
	const rangePrefix = "bytes="

	if stream == nil {
		c.SetResponseCode(fasthttp.StatusInternalServerError)
		return
	}

	if dstream, ok := stream.(DefinedStream); ok {
		c.SetResponseHeader("Last-Modified", dstream.ModTime().UTC().Format(modTimeFormat))
		c.SetResponseHeader("Accept-Ranges", "bytes")

		size := dstream.Size()
		rangeHeader := c.GetRequestHeader("range")
		if len(rangeHeader) > 0 {
			if !strings.HasPrefix(rangeHeader, rangePrefix) {
				c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
				return
			}
			ranges := strings.Split(rangeHeader[len(rangePrefix):], ",")
			if len(ranges) != 1 {
				c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
				return
			}

			ra := ranges[0]
			start, end, ok := strings.Cut(ra, "-")
			if !ok {
				c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
				return
			}
			start, end = textproto.TrimString(start), textproto.TrimString(end)
			var rangeStart, rangeLength int64
			if start == "" {
				//Only supports forward ranges, not backward ranges
				c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
				return
			} else {
				i, err := strconv.ParseInt(start, 10, 64)
				if err != nil || i < 0 {
					//Only supports forward ranges, not backward ranges
				}
				if i >= size {
					// If the range begins after the size of the content,
					// then it does not overlap.
					c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
					return
				}
				rangeStart = i
				if end == "" {
					// If no end is specified, range extends to end of the file.
					rangeLength = size - rangeStart
				} else {
					i, err := strconv.ParseInt(end, 10, 64)
					if err != nil || rangeStart > i {
						c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
						return
					}
					if i >= size {
						i = size - 1
					}
					rangeLength = i - rangeStart + 1
				}
			}

			if _, err := dstream.Seek(rangeStart, io.SeekStart); err != nil {
				c.SetResponseCode(fasthttp.StatusRequestedRangeNotSatisfiable)
				return
			}

			c.SetResponseHeader("Content-Range", fmt.Sprintf("bytes %d-%d/%d", rangeStart, rangeStart+rangeLength-1, size))
			size = rangeLength
			c.SetResponseHeader("Content-Length", strconv.FormatInt(size, 10))
			c.SetResponseCode(fasthttp.StatusPartialContent)
		} else {
			c.SetResponseHeader("Content-Length", strconv.FormatInt(size, 10))
			c.SetResponseCode(fasthttp.StatusOK)
		}

		if !c.IsHead() {
			io.CopyN(c.httpWriter, dstream, size)
		}
	} else {

		c.SetResponseCode(fasthttp.StatusOK)

		if !c.IsHead() {
			c.SetResponseHeader("Transfer-Encoding", "chunked")
			io.Copy(c.httpWriter, dstream)
		}
	}
}

func (c *NetHTTPContext) ServeBytes(content []byte) {
	c.httpWriter.Write(content)
}

func (c *NetHTTPContext) SetResponseCode(code int) {
	c.httpWriter.WriteHeader(code)
}

func (c *NetHTTPContext) DoRedirect(location string, code int) {
	http.Redirect(c.httpWriter, c.httpRequest, location, code)
}

func (c *NetHTTPContext) GetBody() io.Reader {
	return c.httpRequest.Body
}

func (c *NetHTTPContext) IsGet() bool {
	return c.httpRequest.Method == "GET"
}

func (c *NetHTTPContext) IsPost() bool {
	return c.httpRequest.Method == "POST"

}

func (c *NetHTTPContext) IsOptions() bool {
	return c.httpRequest.Method == "OPTIONS"

}

func (c *NetHTTPContext) IsHead() bool {
	return c.httpRequest.Method == "HEAD"
}