// Copyright (C) 2019 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

package sqlite3

/*
#ifndef USE_LIBSQLITE3
#include "amalgamation/sqlite3-binding.h"
#else
#include <sqlite3.h>
#endif
#include <stdlib.h>
*/
import "C"
import (
	"runtime"
	"unsafe"
)

// SQLiteBackup implement interface of Backup.
type SQLiteBackup struct {
	b *C.sqlite3_backup
}

// Backup make backup from src to dest.
func (destConn *SQLiteConn) Backup(dest string, srcConn *SQLiteConn, src string) (*SQLiteBackup, error) {
	destptr := C.CString(dest)
	defer C.free(unsafe.Pointer(destptr))
	srcptr := C.CString(src)
	defer C.free(unsafe.Pointer(srcptr))

	if b := C.sqlite3_backup_init(destConn.db, destptr, srcConn.db, srcptr); b != nil {
		bb := &SQLiteBackup{b: b}
		runtime.SetFinalizer(bb, (*SQLiteBackup).Finish)
		return bb, nil
	}
	return nil, destConn.lastError()
}

// Step to backs up for one step. Calls the underlying `sqlite3_backup_step`
// function.  This function returns a boolean indicating if the backup is done
// and an error signalling any other error. Done is returned if the underlying
// C function returns SQLITE_DONE (Code 101)
func (b *SQLiteBackup) Step(p int) (bool, error) {
	ret := C.sqlite3_backup_step(b.b, C.int(p))
	if ret == C.SQLITE_DONE {
		return true, nil
	} else if ret != 0 && ret != C.SQLITE_LOCKED && ret != C.SQLITE_BUSY {
		return false, Error{Code: ErrNo(ret)}
	}
	return false, nil
}

// Remaining return whether have the rest for backup.
func (b *SQLiteBackup) Remaining() int {
	return int(C.sqlite3_backup_remaining(b.b))
}

// PageCount return count of pages.
func (b *SQLiteBackup) PageCount() int {
	return int(C.sqlite3_backup_pagecount(b.b))
}

// Finish close backup.
func (b *SQLiteBackup) Finish() error {
	return b.Close()
}

// Close close backup.
func (b *SQLiteBackup) Close() error {
	ret := C.sqlite3_backup_finish(b.b)

	// sqlite3_backup_finish() never fails, it just returns the
	// error code from previous operations, so clean up before
	// checking and returning an error
	b.b = nil
	runtime.SetFinalizer(b, nil)

	if ret != 0 {
		return Error{Code: ErrNo(ret)}
	}
	return nil
}