package main

import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
)

// The test binary doubles as the "downloaded agent": started with -version and this variable it prints a version.
func init() {
	if os.Getenv("WXCH_FAKE_AGENT") == "1" && len(os.Args) > 1 && os.Args[1] == "-version" {
		fmt.Println("9.9.9")
		os.Exit(0)
	}
}

func updateFixture(t *testing.T, handler http.HandlerFunc) (wsURL, exe string) {
	t.Setenv("WXCH_FAKE_AGENT", "1")
	srv := httptest.NewServer(handler)
	t.Cleanup(srv.Close)
	exe = filepath.Join(t.TempDir(), "wxch-agent")
	os.WriteFile(exe, []byte("old agent"), 0755)
	old := updateExe
	updateExe = func() (string, error) { return exe, nil }
	t.Cleanup(func() { updateExe = old })
	return "ws" + strings.TrimPrefix(srv.URL, "http") + "/ws/agent", exe
}

func TestSelfUpdateReplacesTheFileAndSaysWhatItNowIs(t *testing.T) {
	self, _ := os.ReadFile(os.Args[0])
	var asked string
	ws, exe := updateFixture(t, func(w http.ResponseWriter, r *http.Request) { asked = r.URL.Path; w.Write(self) })
	v, err := selfUpdate(ws)
	if err != nil {
		t.Fatal(err)
	}
	if v != "9.9.9" || asked != "/dl/wxch-agent-"+runtime.GOARCH {
		t.Fatalf("version %q, asked %q", v, asked)
	}
	if b, _ := os.ReadFile(exe); len(b) != len(self) {
		t.Error("the file was not replaced")
	}
	if _, err := os.Stat(exe + ".new"); err == nil {
		t.Error("the temporary file was left behind")
	}
}

func TestSelfUpdateLeavesTheOldFileWhenSomethingIsWrong(t *testing.T) {
	self, _ := os.ReadFile(os.Args[0])
	cases := map[string]http.HandlerFunc{
		"not found":     func(w http.ResponseWriter, r *http.Request) { http.NotFound(w, r) },
		"not a program": func(w http.ResponseWriter, r *http.Request) { w.Write([]byte("<html>login page</html>")) },
		"cut short": func(w http.ResponseWriter, r *http.Request) {
			w.Header().Set("Content-Length", fmt.Sprint(len(self)))
			w.Write(self[:len(self)/2])
		},
	}
	for name, h := range cases {
		ws, exe := updateFixture(t, h)
		if _, err := selfUpdate(ws); err == nil {
			t.Errorf("%s: no error", name)
		}
		if b, _ := os.ReadFile(exe); string(b) != "old agent" {
			t.Errorf("%s: the old file was damaged", name)
		}
		if _, err := os.Stat(exe + ".new"); err == nil {
			t.Errorf("%s: the temporary file was left behind", name)
		}
	}
}