package timberjack

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"strings"
	"testing"
)

// assert will log the given message if condition is false.
func assert(condition bool, t testing.TB, msg string, v ...interface{}) {
	assertUp(condition, t, 1, msg, v...)
}

// assertUp is like assert, but used inside helper functions, to ensure that
// the file and line number reported by failures corresponds to one or more
// levels up the stack.
func assertUp(condition bool, t testing.TB, caller int, msg string, v ...interface{}) {
	if !condition {
		_, file, line, _ := runtime.Caller(caller + 1)
		v = append([]interface{}{filepath.Base(file), line}, v...)
		fmt.Printf("%s:%d: "+msg+"\n", v...)
		t.FailNow()
	}
}

// equals tests that the two values are equal according to reflect.DeepEqual.
func equals(exp, act interface{}, t testing.TB) {
	equalsUp(exp, act, t, 1)
}

// equalsUp is like equals, but used inside helper functions, to ensure that the
// file and line number reported by failures corresponds to one or more levels
// up the stack.
func equalsUp(exp, act interface{}, t testing.TB, caller int) {
	if !reflect.DeepEqual(exp, act) {
		_, file, line, _ := runtime.Caller(caller + 1)
		fmt.Printf("%s:%d: exp: %v (%T), got: %v (%T)\n",
			filepath.Base(file), line, exp, exp, act, act)
		t.FailNow()
	}
}

// isNil reports a failure if the given value is not nil.  Note that values
// which cannot be nil will always fail this check.
func isNil(obtained interface{}, t testing.TB) {
	isNilUp(obtained, t, 1)
}

// isNilUp is like isNil, but used inside helper functions, to ensure that the
// file and line number reported by failures corresponds to one or more levels
// up the stack.
func isNilUp(obtained interface{}, t testing.TB, caller int) {
	if !_isNil(obtained) {
		_, file, line, _ := runtime.Caller(caller + 1)
		fmt.Printf("%s:%d: expected nil, got: %v\n", filepath.Base(file), line, obtained)
		t.FailNow()
	}
}

// notNil reports a failure if the given value is nil.
func notNil(obtained interface{}, t testing.TB) {
	notNilUp(obtained, t, 1)
}

// notNilUp is like notNil, but used inside helper functions, to ensure that the
// file and line number reported by failures corresponds to one or more levels
// up the stack.
func notNilUp(obtained interface{}, t testing.TB, caller int) {
	if _isNil(obtained) {
		_, file, line, _ := runtime.Caller(caller + 1)
		fmt.Printf("%s:%d: expected non-nil, got: %v\n", filepath.Base(file), line, obtained)
		t.FailNow()
	}
}

// _isNil is a helper function for isNil and notNil, and should not be used
// directly.
func _isNil(obtained interface{}) bool {
	if obtained == nil {
		return true
	}

	switch v := reflect.ValueOf(obtained); v.Kind() {
	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
		return v.IsNil()
	}

	return false
}

// backupFileWithReason returns a backup file name with the given reason.
func backupFileWithReason(dir, reason string) string {
	return filepath.Join(dir, fmt.Sprintf("foobar-%s-%s.log", fakeTime().UTC().Format("2006-01-02T15-04-05.000"), reason))
}

// findBackupFileWithContent searches dir for a backup file whose name ends with
// "-<reason>.log" and whose content equals the expected bytes. The test fails if
// no matching file is found. This is intentionally content-based rather than
// name-based, because the scheduled rotation goroutine may snapshot the fake
// clock at a different instant than the test goroutine does.
func findBackupFileWithContent(t testing.TB, dir, reason string, content []byte) {
	t.Helper()
	suffix := fmt.Sprintf("-%s.log", reason)
	ents, err := os.ReadDir(dir)
	if err != nil {
		t.Fatalf("ReadDir %s: %v", dir, err)
	}
	for _, e := range ents {
		if e.IsDir() || !strings.HasSuffix(e.Name(), suffix) {
			continue
		}
		data, readErr := os.ReadFile(filepath.Join(dir, e.Name()))
		if readErr == nil && bytes.Equal(data, content) {
			return
		}
	}
	t.Fatalf("no backup file with suffix %q containing %q found in %s", suffix, string(content), dir)
}