package selfupdate

import (
	"archive/tar"
	"bytes"
	"compress/gzip"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func makeArchive(t *testing.T, pkg, app, content string) []byte {
	t.Helper()
	var buf bytes.Buffer
	gz := gzip.NewWriter(&buf)
	tw := tar.NewWriter(gz)
	for name, body := range map[string]string{pkg + "/README.md": "hi", pkg + "/" + app: content} {
		if err := tw.WriteHeader(&tar.Header{Name: name, Mode: 0o755, Size: int64(len(body)), Typeflag: tar.TypeReg}); err != nil {
			t.Fatal(err)
		}
		tw.Write([]byte(body))
	}
	tw.Close()
	gz.Close()
	return buf.Bytes()
}

// fakeGitea serves one release with the given tag.
func fakeGitea(t *testing.T, tag string, prerelease bool, corrupt bool) *httptest.Server {
	archive := fmt.Sprintf("demo_%s_linux_amd64.tar.gz", tag)
	data := makeArchive(t, strings.TrimSuffix(archive, ".tar.gz"), "demo", "NEW-BINARY "+tag)
	sum := sha256.Sum256(data)
	sums := hex.EncodeToString(sum[:]) + "  " + archive + "\n"
	if corrupt {
		sums = strings.Repeat("0", 64) + "  " + archive + "\n"
	}
	var srv *httptest.Server
	mux := http.NewServeMux()
	mux.HandleFunc("/api/v1/repos/Veillax/demo/releases/latest", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, `{"tag_name":%q,"prerelease":%v,"assets":[{"name":%q,"browser_download_url":"%s/dl/%s"},{"name":"SHA256SUMS","browser_download_url":"%s/dl/SHA256SUMS"}]}`,
			tag, prerelease, archive, srv.URL, archive, srv.URL)
	})
	mux.HandleFunc("/dl/SHA256SUMS", func(w http.ResponseWriter, r *http.Request) { fmt.Fprint(w, sums) })
	mux.HandleFunc("/dl/"+archive, func(w http.ResponseWriter, r *http.Request) { w.Write(data) })
	srv = httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv
}

func setup(t *testing.T, srv *httptest.Server, current string) (Config, string, *string) {
	exe := filepath.Join(t.TempDir(), "demo")
	os.WriteFile(exe, []byte("OLD-BINARY"), 0o755)
	restarted := new(string)
	return Config{Server: srv.URL, Repo: "Veillax/demo", App: "demo", Current: current, GOOS: "linux", GOARCH: "amd64", ExePath: exe,
		Verify:  func(p, tag string) error { return nil },
		Restart: func(e string) error { *restarted = e; return nil }}, exe, restarted
}

func TestInstallsANewerRelease(t *testing.T) {
	cfg, exe, restarted := setup(t, fakeGitea(t, "v0.2.0", false, false), "v0.1.5")
	tag, err := CheckOnce(context.Background(), cfg)
	if err != nil || tag != "v0.2.0" {
		t.Fatalf("tag=%q err=%v", tag, err)
	}
	if b, _ := os.ReadFile(exe); string(b) != "NEW-BINARY v0.2.0" {
		t.Fatalf("binary is %q", b)
	}
	if *restarted != exe {
		t.Fatalf("restart called with %q", *restarted)
	}
	if _, err := os.Stat(filepath.Join(filepath.Dir(exe), ".demo.new")); err == nil {
		t.Fatal("temporary file left behind")
	}
}

func TestLeavesThingsAloneWhenItShould(t *testing.T) {
	for _, c := range []struct {
		name, current, tag string
		pre                bool
	}{
		{"same version", "v0.2.0", "v0.2.0", false},
		{"never downgrades", "v0.3.0", "v0.2.0", false},
		{"pre-release is skipped", "v0.1.0", "v0.2.0", true},
		{"dev build", "dev", "v0.2.0", false},
		{"local build", "v0.2.0-local", "v0.9.0", false},
	} {
		cfg, exe, restarted := setup(t, fakeGitea(t, c.tag, c.pre, false), c.current)
		tag, _ := CheckOnce(context.Background(), cfg)
		if b, _ := os.ReadFile(exe); tag != "" || string(b) != "OLD-BINARY" || *restarted != "" {
			t.Errorf("%s: changed things (tag=%q binary=%q)", c.name, tag, b)
		}
	}
}

func TestRefusesABadChecksum(t *testing.T) {
	cfg, exe, restarted := setup(t, fakeGitea(t, "v0.2.0", false, true), "v0.1.0")
	if _, err := CheckOnce(context.Background(), cfg); err == nil || !strings.Contains(err.Error(), "checksum") {
		t.Fatalf("err=%v", err)
	}
	if b, _ := os.ReadFile(exe); string(b) != "OLD-BINARY" || *restarted != "" {
		t.Fatal("installed a binary that failed its checksum")
	}
}

func TestKeepsTheOldBinaryWhenTheNewOneFailsItsCheck(t *testing.T) {
	cfg, exe, restarted := setup(t, fakeGitea(t, "v0.2.0", false, false), "v0.1.0")
	cfg.Verify = func(p, tag string) error { return fmt.Errorf("segfault") }
	if _, err := CheckOnce(context.Background(), cfg); err == nil {
		t.Fatal("expected an error")
	}
	if b, _ := os.ReadFile(exe); string(b) != "OLD-BINARY" || *restarted != "" {
		t.Fatal("replaced the binary despite a failed check")
	}
	if _, err := os.Stat(filepath.Join(filepath.Dir(exe), ".demo.new")); err == nil {
		t.Fatal("temporary file left behind")
	}
}

func TestVersionOrdering(t *testing.T) {
	for _, c := range []struct {
		a, b string
		want bool
	}{{"v0.1.10", "v0.1.9", true}, {"v1.0.0", "v0.99.99", true}, {"v0.1.2", "v0.1.2", false}, {"v0.1.1", "v0.2.0", false}} {
		a, _ := parseVersion(c.a)
		b, _ := parseVersion(c.b)
		if a.newerThan(b) != c.want {
			t.Errorf("%s newer than %s: want %v", c.a, c.b, c.want)
		}
	}
}