package upgrade

import (
	"fmt"
	"io"

	"git.xdrm.io/go/ws/internal/http/reader"
)

// If origin is required
const bypassOriginPolicy = true

// Request represents an HTTP Upgrade request
type Request struct {
	first bool // whether the first line has been read (GET uri HTTP/version)

	// status code
	code StatusCode

	// request line
	request Line

	// data to check origin (depends of reading order)
	host        string
	port        uint16 // 0 if not set
	origin      string
	validPolicy bool

	// ws data
	key       []byte
	protocols [][]byte

	// required fields check
	hasConnection bool
	hasUpgrade    bool
	hasVersion    bool
}

// Parse builds an upgrade HTTP request
// from a reader (typically bufio.NewRead of the socket)
func Parse(r io.Reader) (request *Request, err error) {

	req := &Request{
		code: 500,
	}

	/* (1) Parse request
	---------------------------------------------------------*/
	// 1. Get chunk reader
	cr := reader.NewReader(r)
	if err != nil {
		return req, fmt.Errorf("create chunk reader: %w", err)
	}

	// 2. Parse header line by line
	for {

		line, err := cr.Read()
		if err == io.EOF {
			break
		}

		if err != nil {
			return req, err
		}

		err = req.parseHeader(line)

		if err != nil {
			return req, err
		}

	}

	// 3. Check completion
	err = req.isComplete()
	if err != nil {
		req.code = BadRequest
		return req, err
	}

	req.code = SwitchingProtocols
	return req, nil

}

// StatusCode returns the status current
func (r Request) StatusCode() StatusCode {
	return r.code
}

// BuildResponse builds a response from the request
func (r *Request) BuildResponse() *Response {

	inst := &Response{}

	// 1. Copy code
	inst.SetStatusCode(r.code)

	// 2. Set Protocol
	if len(r.protocols) > 0 {
		inst.SetProtocol(r.protocols[0])
	}

	// 4. Process key
	inst.ProcessKey(r.key)

	return inst
}

// GetURI returns the actual URI
func (r Request) GetURI() string {
	return r.request.GetURI()
}

// parseHeader parses any http request line
// (header and request-line)
func (r *Request) parseHeader(b []byte) error {

	/* (1) First line -> GET {uri} HTTP/{version}
	---------------------------------------------------------*/
	if !r.first {

		err := r.request.Parse(b)

		if err != nil {
			r.code = BadRequest
			return &InvalidRequest{"Request-Line", err.Error()}
		}

		r.first = true
		return nil

	}

	/* (2) Other lines -> Header-Name: Header-Value
	---------------------------------------------------------*/
	// 1. Try to parse header
	head, err := ReadHeader(b)
	if err != nil {
		r.code = BadRequest
		return fmt.Errorf("parse header: %w", err)
	}

	// 2. Manage header
	switch head.Name {
	case Host:
		err = r.extractHostPort(head.Values)
	case Origin:
		err = r.extractOrigin(head.Values)
	case Upgrade:
		err = r.checkUpgrade(head.Values)
	case Connection:
		err = r.checkConnection(head.Values)
	case WSVersion:
		err = r.checkVersion(head.Values)
	case WSKey:
		err = r.extractKey(head.Values)
	case WSProtocol:
		err = r.extractProtocols(head.Values)

	default:
		return nil
	}

	// dispatch error
	if err != nil {
		return err
	}

	return nil

}

// isComplete returns whether the Upgrade Request
// is complete (no missing required item)
func (r Request) isComplete() error {

	// 1. Request-Line
	if !r.first {
		return &IncompleteRequest{"Request-Line"}
	}

	// 2. Host
	if len(r.host) == 0 {
		return &IncompleteRequest{"Host"}
	}

	// 3. Origin
	if !bypassOriginPolicy && len(r.origin) == 0 {
		return &IncompleteRequest{"Origin"}
	}

	// 4. Connection
	if !r.hasConnection {
		return &IncompleteRequest{"Connection"}
	}

	// 5. Upgrade
	if !r.hasUpgrade {
		return &IncompleteRequest{"Upgrade"}
	}

	// 6. Sec-WebSocket-Version
	if !r.hasVersion {
		return &IncompleteRequest{"Sec-WebSocket-Version"}
	}

	// 7. Sec-WebSocket-Key
	if len(r.key) < 1 {
		return &IncompleteRequest{"Sec-WebSocket-Key"}
	}

	return nil

}