import logging
import os.path
import errno
import prserv
import time

try:
    import sqlite3
except ImportError:
    from pysqlite2 import dbapi2 as sqlite3

logger = logging.getLogger("BitBake.PRserv")

sqlversion = sqlite3.sqlite_version_info
if sqlversion[0] < 3 or (sqlversion[0] == 3 and sqlversion[1] < 3):
    raise Exception("sqlite3 version 3.3.0 or later is required.")

#
# "No History" mode - for a given query tuple (version, pkgarch, checksum),
# the returned value will be the largest among all the values of the same
# (version, pkgarch). This means the PR value returned can NOT be decremented.
#
# "History" mode - Return a new higher value for previously unseen query
# tuple (version, pkgarch, checksum), otherwise return historical value.
# Value can decrement if returning to a previous build.
#

class PRTable(object):
    def __init__(self, conn, table, nohist):
        self.conn = conn
        self.nohist = nohist
        self.dirty = False
        if nohist:
            self.table = "%s_nohist" % table 
        else:
            self.table = "%s_hist" % table 

        self._execute("CREATE TABLE IF NOT EXISTS %s \
                    (version TEXT NOT NULL, \
                    pkgarch TEXT NOT NULL,  \
                    checksum TEXT NOT NULL, \
                    value INTEGER, \
                    PRIMARY KEY (version, pkgarch, checksum));" % self.table)

    def _execute(self, *query):
        """Execute a query, waiting to acquire a lock if necessary"""
        start = time.time()
        end = start + 20
        while True:
            try:
                return self.conn.execute(*query)
            except sqlite3.OperationalError as exc:
                if 'is locked' in str(exc) and end > time.time():
                    continue
                raise exc

    def sync(self):
        self.conn.commit()
        self._execute("BEGIN EXCLUSIVE TRANSACTION")

    def sync_if_dirty(self):
        if self.dirty:
            self.sync()
            self.dirty = False

    def _getValueHist(self, version, pkgarch, checksum):
        data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                           (version, pkgarch, checksum))
        row=data.fetchone()
        if row != None:
            return row[0]
        else:
            #no value found, try to insert
            try:
                self._execute("INSERT INTO %s VALUES (?, ?, ?, (select ifnull(max(value)+1,0) from %s where version=? AND pkgarch=?));"
                           % (self.table,self.table),
                           (version,pkgarch, checksum,version, pkgarch))
            except sqlite3.IntegrityError as exc:
                logger.error(str(exc))

            self.dirty = True

            data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                               (version, pkgarch, checksum))
            row=data.fetchone()
            if row != None:
                return row[0]
            else:
                raise prserv.NotFoundError

    def _getValueNohist(self, version, pkgarch, checksum):
        data=self._execute("SELECT value FROM %s \
                            WHERE version=? AND pkgarch=? AND checksum=? AND \
                            value >= (select max(value) from %s where version=? AND pkgarch=?);" 
                            % (self.table, self.table),
                            (version, pkgarch, checksum, version, pkgarch))
        row=data.fetchone()
        if row != None:
            return row[0]
        else:
            #no value found, try to insert
            try:
                self._execute("INSERT OR REPLACE INTO %s VALUES (?, ?, ?, (select ifnull(max(value)+1,0) from %s where version=? AND pkgarch=?));"
                               % (self.table,self.table),
                               (version, pkgarch, checksum, version, pkgarch))
            except sqlite3.IntegrityError as exc:
                logger.error(str(exc))
                self.conn.rollback()

            self.dirty = True

            data=self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                               (version, pkgarch, checksum))
            row=data.fetchone()
            if row != None:
                return row[0]
            else:
                raise prserv.NotFoundError

    def getValue(self, version, pkgarch, checksum):
        if self.nohist:
            return self._getValueNohist(version, pkgarch, checksum)
        else:
            return self._getValueHist(version, pkgarch, checksum)

    def _importHist(self, version, pkgarch, checksum, value):
        val = None 
        data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                           (version, pkgarch, checksum))
        row = data.fetchone()
        if row != None:
            val=row[0]
        else:
            #no value found, try to insert
            try:
                self._execute("INSERT INTO %s VALUES (?, ?, ?, ?);"  % (self.table),
                           (version, pkgarch, checksum, value))
            except sqlite3.IntegrityError as exc:
                logger.error(str(exc))

            self.dirty = True

            data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=?;" % self.table,
                           (version, pkgarch, checksum))
            row = data.fetchone()
            if row != None:
                val = row[0]
        return val

    def _importNohist(self, version, pkgarch, checksum, value):
        try:
            #try to insert
            self._execute("INSERT INTO %s VALUES (?, ?, ?, ?);"  % (self.table),
                           (version, pkgarch, checksum,value))
        except sqlite3.IntegrityError as exc:
            #already have the record, try to update
            try:
                self._execute("UPDATE %s SET value=? WHERE version=? AND pkgarch=? AND checksum=? AND value<?"  
                              % (self.table),
                               (value,version,pkgarch,checksum,value))
            except sqlite3.IntegrityError as exc:
                logger.error(str(exc))

        self.dirty = True

        data = self._execute("SELECT value FROM %s WHERE version=? AND pkgarch=? AND checksum=? AND value>=?;" % self.table,
                            (version,pkgarch,checksum,value))
        row=data.fetchone()
        if row != None:
            return row[0]
        else:
            return None

    def importone(self, version, pkgarch, checksum, value):
        if self.nohist:
            return self._importNohist(version, pkgarch, checksum, value)
        else:
            return self._importHist(version, pkgarch, checksum, value)

    def export(self, version, pkgarch, checksum, colinfo):
        metainfo = {}
        #column info 
        if colinfo:
            metainfo['tbl_name'] = self.table
            metainfo['core_ver'] = prserv.__version__
            metainfo['col_info'] = []
            data = self._execute("PRAGMA table_info(%s);" % self.table)
            for row in data:
                col = {}
                col['name'] = row['name']
                col['type'] = row['type']
                col['notnull'] = row['notnull']
                col['dflt_value'] = row['dflt_value']
                col['pk'] = row['pk']
                metainfo['col_info'].append(col)

        #data info
        datainfo = []

        if self.nohist:
            sqlstmt = "SELECT T1.version, T1.pkgarch, T1.checksum, T1.value FROM %s as T1, \
                    (SELECT version,pkgarch,max(value) as maxvalue FROM %s GROUP BY version,pkgarch) as T2 \
                    WHERE T1.version=T2.version AND T1.pkgarch=T2.pkgarch AND T1.value=T2.maxvalue " % (self.table, self.table)
        else:
            sqlstmt = "SELECT * FROM %s as T1 WHERE 1=1 " % self.table
        sqlarg = []
        where = ""
        if version:
            where += "AND T1.version=? "
            sqlarg.append(str(version))
        if pkgarch:
            where += "AND T1.pkgarch=? "
            sqlarg.append(str(pkgarch))
        if checksum:
            where += "AND T1.checksum=? "
            sqlarg.append(str(checksum))

        sqlstmt += where + ";"

        if len(sqlarg):
            data = self._execute(sqlstmt, tuple(sqlarg))
        else:
            data = self._execute(sqlstmt)
        for row in data:
            if row['version']:
                col = {}
                col['version'] = row['version']
                col['pkgarch'] = row['pkgarch']
                col['checksum'] = row['checksum']
                col['value'] = row['value']
                datainfo.append(col)
        return (metainfo, datainfo)

class PRData(object):
    """Object representing the PR database"""
    def __init__(self, filename, nohist=True):
        self.filename=os.path.abspath(filename)
        self.nohist=nohist
        #build directory hierarchy
        try:
            os.makedirs(os.path.dirname(self.filename))
        except OSError as e:
            if e.errno != errno.EEXIST:
                raise e
        self.connection=sqlite3.connect(self.filename, isolation_level="EXCLUSIVE", check_same_thread = False)
        self.connection.row_factory=sqlite3.Row
        self.connection.execute("pragma synchronous = off;")
        self.connection.execute("PRAGMA journal_mode = WAL;")
        self._tables={}

    def __del__(self):
        self.connection.close()

    def __getitem__(self,tblname):
        if not isinstance(tblname, basestring):
            raise TypeError("tblname argument must be a string, not '%s'" %
                            type(tblname))
        if tblname in self._tables:
            return self._tables[tblname]
        else:
            tableobj = self._tables[tblname] = PRTable(self.connection, tblname, self.nohist)
            return tableobj

    def __delitem__(self, tblname):
        if tblname in self._tables:
            del self._tables[tblname]
        logger.info("drop table %s" % (tblname))
        self.connection.execute("DROP TABLE IF EXISTS %s;" % tblname)