package handlers

import (
	"compress/gzip"
	"io"
	"log/slog"
	"net/http"

	securejoin "github.com/cyphar/filepath-securejoin"
	"olexsmir.xyz/mugit/internal/git/gitservice"
)

// multiplex, check if the request smells like gitprotocol-http(5), if so, it
// passes it to git smart http, otherwise renders templates
func (h *handlers) multiplex(w http.ResponseWriter, r *http.Request) {
	if r.URL.RawQuery == "service=git-receive-pack" {
		w.WriteHeader(http.StatusBadRequest)
		w.Write([]byte("http pushing is not supported"))
		return
	}

	path := r.PathValue("rest")
	if path == "info/refs" && r.Method == "GET" && r.URL.RawQuery == "service=git-upload-pack" {
		h.infoRefs(w, r)
	} else if path == "git-upload-pack" && r.Method == "POST" {
		h.uploadPack(w, r)
	} else if r.Method == "GET" {
		h.repoIndex(w, r)
	}
}

func (h *handlers) infoRefs(w http.ResponseWriter, r *http.Request) {
	name := getNormalizedName(r.PathValue("name"))
	_, err := h.openPublicRepo(name, "")
	if err != nil {
		h.write404(w, err)
		return
	}

	w.Header().Set("content-type", "application/x-git-upload-pack-advertisement")
	w.WriteHeader(http.StatusOK)

	repoPath := repoNameToPath(name)
	path, err := securejoin.SecureJoin(h.c.Repo.Dir, repoPath)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		slog.Error("git: info/refs", "err", err)
		return
	}

	if err := gitservice.InfoRefs(path, w); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		slog.Error("git: info/refs", "err", err)
		return
	}
}

func (h *handlers) uploadPack(w http.ResponseWriter, r *http.Request) {
	name := getNormalizedName(r.PathValue("name"))
	_, err := h.openPublicRepo(name, "")
	if err != nil {
		h.write404(w, err)
		return
	}

	w.Header().Set("content-type", "application/x-git-upload-pack-result")
	w.Header().Set("Connection", "Keep-Alive")
	w.Header().Set("Transfer-Encoding", "chunked")
	w.WriteHeader(http.StatusOK)

	reader := io.Reader(r.Body)
	if r.Header.Get("Content-Encoding") == "gzip" {
		gr, gerr := gzip.NewReader(r.Body)
		if gerr != nil {
			w.WriteHeader(http.StatusInternalServerError)
			slog.Error("git: gzip reader", "err", gerr)
			return
		}
		defer gr.Close()
		reader = gr
	}

	repoPath := repoNameToPath(name)
	path, err := securejoin.SecureJoin(h.c.Repo.Dir, repoPath)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		slog.Error("git: info/refs", "err", err)
		return
	}

	if err := gitservice.UploadPack(path, true, reader, newFlushWriter(w)); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		slog.Error("git: upload-pack", "err", err)
		return
	}
}

type flushWriter struct {
	w io.Writer
	f http.Flusher
}

func newFlushWriter(w http.ResponseWriter) io.Writer {
	f, _ := w.(http.Flusher)
	return &flushWriter{w: w, f: f}
}

func (fw *flushWriter) Write(p []byte) (int, error) {
	n, err := fw.w.Write(p)
	if fw.f != nil {
		fw.f.Flush()
	}
	return n, err
}