#!/usr/bin/env python3

#

# Copy data between tables with same table schema.

#

# Copies full table, target table must be empty.

# Can copy multiple tables in one run.

# Sorts the tables according to references.

#

# This may be used instead of dump/restore.

#

import io

from pgtoolkit import toolbase, pgmanager, pgbrowser, pgdatacopy

from pgtoolkit.progresswrapper import ProgressWrapper

class TableCopyTool(toolbase.SrcDstTablesTool):

    def __init__(self):

        toolbase.SrcDstTablesTool.__init__(self, name='tablecopy', desc='Table copy tool.')

        self.parser.add_argument('-n', '--no-action', dest='noaction', action='store_true',

            help="Do nothing, just print tables to be copied. Useful in combination with --regex.")

        self.parser.add_argument('--no-sort', dest='nosort', action='store_true',

            help="Do not sort. By default, tables are sorted by foreign key references.")

        self.init()

    def main(self):

        self.srcconn = self.pgm.get_conn('src')

        self.dstconn = self.pgm.get_conn('dst')

        dc = pgdatacopy.PgDataCopy(self.srcconn, self.dstconn)

        if self.args.nosort:

            for table in self.tables():

                self.copy_table(dc, *table)

        else:

            # sort tables with respect to references

            details = dict()

            pending = set()

            references = dict()

            # build list of all table to be copied (pending) and references map

            for table in self.tables():

                srcschema, srctable, dstschema, dsttable = table

                name = dstschema + '.' + dsttable

                details[name] = table

                pending.add(name)

                references[name] = self.get_references(dstschema, dsttable)

            # copy files with fulfilled references, repeat until all done

            while pending:

                for name in list(pending):

                    ok = True

                    for ref in references[name]:

                        if ref in pending:

                            ok = False

                    if ok:

                        table = details[name]

                        self.copy_table(dc, *table)

                        pending.remove(name)

    def get_references(self, schema, table):

        browser = pgbrowser.PgBrowser(self.dstconn)

        cons = browser.list_constraints(table, schema)

        return [con['fschema'] + '.' + con['fname'] for con in cons if con['type'] == 'f']

    def copy_table(self, dc, srcschema, srctable, dstschema, dsttable):

        print('Copying [%s] %s.%s --> [%s] %s.%s' % (

            self.args.src, srcschema, srctable,

            self.args.dst, dstschema, dsttable))

        if self.args.noaction:

            return

        dc.set_source(srctable, srcschema)

        dc.set_destination(dsttable, dstschema)

        try:

            dc.check()

        except pgdatacopy.TargetNotEmptyError as e:

            print(' - error:', str(e))

            return

        print(' - read                           ')

        buf = io.BytesIO()

        wrapped = ProgressWrapper(buf)

        dc.read(wrapped)

        data = buf.getvalue()

        buf.close()

        print(' - write                          ')

        buf = io.BytesIO(data)

        wrapped = ProgressWrapper(buf, len(data))

        dc.write(wrapped)

        buf.close()

        print(' - analyze                        ')

        dc.analyze()

tool = TableCopyTool()

tool.main()