/*
tofuproxy -- flexible HTTP/HTTPS proxy, TLS terminator, X.509 TOFU
             manager, WARC/geminispace browser
Copyright (C) 2021 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package rounds

import (
	_ "embed"
	"fmt"
	"html/template"
	"io"
	"log"
	"net/http"
	"path"
	"sort"
	"strings"

	"github.com/dustin/go-humanize"
	"go.stargrave.org/tofuproxy/fifos"
	"go.stargrave.org/tofuproxy/warc"
)

const WARCEntrypoint = "http://warc/"

var (
	WARCOnly bool

	//go:embed warc-index.tmpl
	TmplWARCIndexRaw string
	TmplWARCIndex    = template.Must(template.New("warc-index").Parse(TmplWARCIndexRaw))
)

type WARCEntry struct {
	WARC string
	URI  string
	Size string
}

type ByDepth []*WARCEntry

func (a ByDepth) Len() int {
	return len(a)
}

func (a ByDepth) Swap(i, j int) {
	a[i], a[j] = a[j], a[i]
}

func (a ByDepth) Less(i, j int) bool {
	ci := len(a[i].WARC)
	cj := len(a[j].WARC)
	if ci != cj {
		return ci < cj
	}
	uriI := strings.TrimSuffix(a[i].URI, "/")
	uriJ := strings.TrimSuffix(a[j].URI, "/")
	ci = strings.Count(uriI, "/")
	cj = strings.Count(uriJ, "/")
	if ci != cj {
		return ci < cj
	}
	return len(uriI) < len(uriJ)
}

func RoundWARC(
	host string,
	resp *http.Response,
	w http.ResponseWriter,
	req *http.Request,
) (bool, error) {
	if req.URL.String() == WARCEntrypoint {
		var entries []*WARCEntry
		warc.WARCsM.RLock()
		for warcPath, uris := range warc.WARCs {
			for uri, rec := range uris {
				entries = append(entries, &WARCEntry{
					path.Base(warcPath),
					uri,
					humanize.IBytes(uint64(rec.TotalSize())),
				})
			}
		}
		warc.WARCsM.RUnlock()
		sort.Sort(ByDepth(entries))
		err := TmplWARCIndex.Execute(w, struct{ Entries []*WARCEntry }{entries})
		if err == nil {
			return false, nil
		} else {
			log.Printf("WARC: error during %s: %+v\n", req.URL, err)
			return false, err
		}
	}

	var rec *warc.Record
	var warcPath string
	var uris map[string]*warc.Record
	hostOrig := req.URL.Host
	if req.URL.Scheme == "https" {
		req.URL.Host = strings.TrimSuffix(req.URL.Host, ":443")
	}
	warc.WARCsM.RLock()
	for warcPath, uris = range warc.WARCs {
		rec = uris[req.URL.String()]
		if rec != nil {
			break
		}
	}
	warc.WARCsM.RUnlock()
	req.URL.Host = hostOrig
	if rec == nil {
		if WARCOnly {
			http.NotFound(w, req)
			fifos.LogNonOK <- fmt.Sprintf("%s %s\tnot in WARC", req.Method, req.URL)
			return false, nil
		}
		return true, nil
	}

	wr, err := rec.Reader(true, warc.WARCsOffsets)
	if err != nil {
		log.Printf("WARC: error during %s: %+v\n", req.URL, err)
		return false, err
	}
	defer wr.Close()
	hj, ok := w.(http.Hijacker)
	if !ok {
		http.Error(w, "can not hijack", http.StatusInternalServerError)
		return false, err
	}
	conn, _, err := hj.Hijack()
	if err != nil {
		panic(err)
	}
	_, err = io.Copy(conn, wr)
	conn.Close()
	fifos.LogWARC <- fmt.Sprintf(
		"%s %s\t%s\t%s\t%s",
		req.Method, req.URL,
		strings.TrimSuffix(rec.Hdr.Get("Content-Type"), ";msgtype=response"),
		warcPath,
		humanize.IBytes(uint64(rec.TotalSize())),
	)
	return false, err
}