import sqlite3
import os
import sys

#TODO: update...compare with DbMySql.py
class DbSQLite(object):
    
    ## Constructor
    #
    # @param host string db file path
    # @param cfgFileName string configuration file name
    #
    # @note when a parameter is left blank, the constructor is able
    #   to set attribute values from environment variable: REPET_HOST,
    #   
    def __init__(self, host = ""):
        if host != "":
            self.host = host
        else:
            msg = "ERROR: no host specified"
            sys.stderr.write( "%s\n" % msg )
            sys.exit(1)
        # remove open() and cursor from init() use directly outside this class ...
        self.open()
        self.cursor = self.db.cursor()
    
    ## Connect to the DbSQLite database
    #
    # @param verbose integer (default = 0)
    #
    def open( self, verbose = 0, nb = 0 ):
        try:
            #sqlite.connect(":memory:", check_same_thread = False)
            self.db = sqlite3.connect(self.host, check_same_thread= False, isolation_level=None, detect_types=sqlite3.PARSE_DECLTYPES)
        except sqlite3.Error, e:
            if verbose > 0:
                print "ERROR %s" % e
                sys.stdout.flush()
            return False
        return True
    
    ## Execute a SQL query
    #
    # @param qry string SQL query to execute
    # @param params parameters of SQL query 
    #
    def execute( self, qry, params=None ):
        try : 
            if params == None:
                self.cursor.execute( qry )
            else:
                self.cursor.execute( qry, params )
        except Exception, e:
            #TODO Must be test 
            try : 
                if params == None:
                    self.cursor.execute( qry )
                else:
                    self.cursor.execute( qry, params )
            except Exception, e:
                    print "Erreur : %s" % e
                    
    ## Retrieve the results of a SQL query
    #  
    def fetchall(self):
        return self.cursor.fetchall()
    
    ## Record a new table in the 'info_table' table
    #
    # @param tableName string table name
    # @param info string information on the table origin
    #
    def updateInfoTable( self, tableName, info ):
        if not self.doesTableExist( "info_tables" ):
            sqlCmd = "CREATE TABLE info_tables ( name varchar(255), file varchar(255) )"
            self.execute( sqlCmd )
        sqlCmd = 'INSERT INTO info_tables VALUES ("%s","%s")' % (tableName, info)
        self.execute( sqlCmd )
   
    def createTable(self, tableName, dataType, overwrite=False, verbose=0):
        if verbose > 0:
            print "creating table '%s' from file '%s' of type '%s'..." % (tableName, dataType)
            sys.stdout.flush()
        if overwrite:
            self.dropTable(tableName)   
        if dataType.lower() in ["job", "jobs"]:
            self.createJobTable(tableName)
        else:
            print "ERROR: unknown type %s" % (dataType)
            self.close()
            sys.exit(1)
        if verbose > 0:
            print "done!"; sys.stdout.flush()
    
    ## Create a job table
    #
    # @param tablename new table name
    #
    def createJobTable( self, tablename ):
        sqlCmd = "CREATE TABLE %s" % ( tablename )
        sqlCmd += " ( jobid INT UNSIGNED"
        sqlCmd += ", jobname VARCHAR(255)"
        sqlCmd += ", groupid VARCHAR(255)"
        sqlCmd += ", command TEXT"
        sqlCmd += ", launcher VARCHAR(1024)"
        sqlCmd += ", queue VARCHAR(255)"
        sqlCmd += ", status VARCHAR(255)"
        sqlCmd += ", time timestamp"
        sqlCmd += ", node VARCHAR(255) )"
        self.execute( sqlCmd )
        
        self.updateInfoTable( tablename, "job table" )
        sqlCmd = "CREATE INDEX igroupid ON " + tablename + " ( groupid )"
        self.execute( sqlCmd )
    
    ## Test if a table exists
    #
    # @param table string table name
    # @return boolean True if the table exists, False otherwise
    #       
    def doesTableExist( self, table ):
        qry = "PRAGMA table_info(%s)" % (table)
        self.execute( qry )
        results = self.cursor.fetchall()
        if results:
            return True
        return False
    
    def isEmpty( self, tableName ):
        return self.getSize( tableName ) == 0
    
    ## Give the rows number of the table
    #
    # @param tableName string table name
    #
    def getSize( self, tableName ):
        qry = "SELECT count(*) FROM %s;" % ( tableName )
        self.execute( qry )
        res = self.fetchall()
        return int( res[0][0] )
    
    ## Remove a table if it exists
    #
    # @param table string table name
    # @param verbose integer (default = 0)
    #
    def dropTable( self, table, verbose = 0 ):
        if self.doesTableExist( table ):
            sqlCmd = "DROP TABLE %s" % ( table )
            self.execute( sqlCmd )
            sqlCmd = 'DELETE FROM info_tables WHERE name = "%s"' % ( table )
            self.execute( sqlCmd )
            
    ## Get a list with the fields
    #                    
    def getFieldList( self, table ):
        lFields = []
        sqlCmd = "PRAGMA table_info(%s)" % ( table )
        self.execute( sqlCmd )
        lResults = self.fetchall()
        for res in lResults:
            lFields.append( res[1] )
        return lFields
    
    ## delete this SQLite database session
    #
    def delete(self):
        os.remove(self.host)
        
    ## Close the connection
    #   
    def close( self ):
        self.db.close()