// Copyright (C) 2014 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

/*
#include <sqlite3.h>
#include <stdlib.h>
*/
import "C"
import (
	"runtime"
	"unsafe"
)

type SQLiteBackup struct {
	b *C.sqlite3_backup
}

func (c *SQLiteConn) Backup(dest string, conn *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(c.db, destptr, conn.db, srcptr); b != nil {
		bb := &SQLiteBackup{b: b}
		runtime.SetFinalizer(bb, (*SQLiteBackup).Finish)
		return bb, nil
	}
	return nil, c.lastError()
}

// 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
}

func (b *SQLiteBackup) Remaining() int {
	return int(C.sqlite3_backup_remaining(b.b))
}

func (b *SQLiteBackup) PageCount() int {
	return int(C.sqlite3_backup_pagecount(b.b))
}

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

func (b *SQLiteBackup) Close() error {
	ret := C.sqlite3_backup_finish(b.b)
	if ret != 0 {
		return Error{Code: ErrNo(ret)}
	}
	b.b = nil
	runtime.SetFinalizer(b, nil)
	return nil
}
