package httpd

import (
	"net/http"
	"strconv"

	"gitbay.org/gitbay/internal/protocol"
	"gitbay.org/gitbay/internal/store"
)

// mrRangeDiff renders what changed between two revisions of a merge
// request — the same comparison `mr range-diff` prints on the CLI and
// the iOS app already show — so a reviewer whose approval a force-push
// staled can see what moved without leaving the browser (#269).
func (s *Server) mrRangeDiff(w http.ResponseWriter, r *http.Request) {
	p, ok := s.repoFor(w, r, "")
	if !ok {
		return
	}
	p.Tab = "merge requests"
	n, err := strconv.ParseInt(r.PathValue("n"), 10, 64)
	if err != nil {
		s.notFound(w, r)
		return
	}
	m, err := s.st.MRByNumber(p.Repo.ID, n)
	if err != nil {
		s.notFound(w, r)
		return
	}

	viewer := s.webViewer(r)
	argv := mrArgs(r, "range-diff")
	if from := r.URL.Query().Get("from"); from != "" {
		argv = append(argv, "--from", from)
	}
	if to := r.URL.Query().Get("to"); to != "" {
		argv = append(argv, "--to", to)
	}
	out, msg, code := s.runControlCode(viewer, argv)
	if code == protocol.ExitNotFound {
		s.notFound(w, r)
		return
	}
	errMsg := ""
	if code != protocol.ExitOK {
		errMsg = msg
	}
	s.render(w, "mrrangediff.html", struct {
		repoPage
		MR    store.MR
		Diff  string
		Error string
	}{p, m, out, errMsg})
}