// Copyright 2024 Matthew Rich <matthewrich.conf@gmail.com>. All rights reserved.

package transport

import (
_	"errors"
	"io"
_	"os"
	"net/url"
	"net/http"
	"fmt"
	"context"
	"path/filepath"
	"io/fs"
	"decl/internal/identifier"
	"strconv"
)

type HTTP struct {
	uri *url.URL
	path string
	gzip bool
	exttype string
	fileext string

	ctx context.Context
	get *HTTPConnection
	Client *http.Client
}

func HTTPExists(u *url.URL) bool {
	resp, err := http.Head(u.String())
	if err == nil && resp.StatusCode == 200 {
		return true
	}
	return false
}

func NewHTTP(u *url.URL, ctx context.Context) (h *HTTP, err error) {
	h = &HTTP {
		ctx: ctx,
		uri: u,
		path: filepath.Join(u.Hostname(), u.RequestURI()),
		Client: http.DefaultClient,
	}

	h.extension()
	h.DetectGzip()
	return
}

func (h *HTTP) extension() {
	id := identifier.ID(h.path)
	h.exttype, h.fileext = id.Extension()
}

func (h *HTTP) DetectGzip() {
	h.gzip = (h.uri.Query().Get("gzip") == "true" || h.fileext == "gz") 
}

func (h *HTTP) URI() *url.URL {
	return h.uri
}

func (h *HTTP) Path() string {
	return h.path
}

func (h *HTTP) Signature() (documentSignature string) {
	if h.get.Response() != nil {
		documentSignature = h.get.Response().Header.Get("Signature")
		if documentSignature == "" {
			signatureResp, signatureErr := h.Client.Get(fmt.Sprintf("%s.sig", h.uri.String()))
			if signatureErr == nil {
				defer signatureResp.Body.Close()
				readSignatureBody, readSignatureErr := io.ReadAll(signatureResp.Body)
				if readSignatureErr == nil {
					documentSignature = string(readSignatureBody)
				}
			}
		}
	}
	return documentSignature
}

func (h *HTTP) Stat() (info fs.FileInfo, err error) {
	uri := h.uri.String()
	var response *http.Response
	if response, err = http.Head(uri); err != nil {
		return
	}
	defer response.Body.Close()
	
	if response.StatusCode > 399 {
		err = ErrTransportResourceAbsent
		return
	}
	fi := NewHTTPFileInfo(uri)
	contentLength := response.Header.Get("Content-Length")
	if contentLength != "" {
		if fi.ContentLength, err = strconv.ParseInt(contentLength, 10, 64); err != nil {
			return
		}
	}
	if response.Header.Get("Last-Modified") != "" {
		fi.LastModified, _ = http.ParseTime(response.Header.Get("Last-Modified"))
	}
	fi.ContentType = response.Header.Get("Content-Type")
	return fi, err
}

func (h *HTTP) ContentType() (contenttype string) {
	contenttype = h.get.Response().Header.Get("Content-Type")
	switch contenttype {
	case "application/octet-stream":
		return h.exttype
	default:
	}
	return
}

func (h *HTTP) SetGzip(gzip bool) {
	h.gzip = gzip
}

func (h *HTTP) Gzip() bool {
	return h.gzip
}