import boto3
import os
import random
import time
import pyarrow as pa
import pyarrow.dataset
import pprint
import datetime
import json
from minerva import parallel_map

pp = pprint.PrettyPrinter(indent=4)

class Redshift:
    def __init__(self, handler, output, db=None, cluster=None, workgroup=None, secret=None):
        self.handler   = handler
        self.client    = handler.session.client("redshift-data")
        self.output    = output
        self.database  = db
        self.cluster   = cluster
        self.workgroup = workgroup
        self.secret    = secret

        if workgroup:
            cli = handler.session.client("redshift-serverless")
            wg  = cli.get_workgroup(workgroupName=workgroup)
            self.rpus = wg['workgroup']['baseCapacity']

    def query(self, sql):
        q = Query(self, sql)
        q.run()
        return q

    def execute(self, sql):
        e = Execute(self, sql)
        e.run()
        return e


class Execute:
    """
    Execute will not return results, but will execute the SQL and return the final state.
    Execute is meant to be used for DML statements such as CREATE DATABASE/TABLE
    """
    def __init__(self, redshift, sql):
        self.redshift     = redshift
        self.handler      = redshift.handler
        self.client       = redshift.client
        self.sql          = sql
        self.info_cache   = None
        self.status_cache = None
        self.ds           = None
        self.files        = None
        self.temps        = []

    def query(self):
        return self.sql


    def run(self):
        if self.redshift.cluster:
            resp  = self.client.execute_statement(Sql               = self.query(),
                                                  Database          = self.redshift.database,
                                                  ClusterIdentifier = self.redshift.cluster)
        else:
            params = {"WorkgroupName": self.redshift.workgroup}
            if self.redshift.secret:
                params['SecretArn'] = self.redshift.secret

            resp  = self.client.execute_statement(Sql=self.query(),
                                                  Database=self.redshift.database,
                                                  **params)

        self.query_id = resp['Id']
        return resp


    def status(self):
        return self.info()['Status']


    def info(self):
        if self.status_cache in ['FINISHED', 'ABORTED', 'FAILED']:
            return self.info_cache

        res = self.client.describe_statement(Id=self.query_id)
        self.info_cache   = res
        self.status_cache = res['Status']

        return self.info_cache


    # Block until the SQL has finished running
    def finish(self):
        stat = self.status()
        while stat in ['SUBMITTED', 'PICKED', 'STARTED']:
            time.sleep(5)
            stat = self.status()

        self.runtime = self.info_cache['UpdatedAt'] - self.info_cache['CreatedAt']

        if self.redshift.rpus:
            # $0.36 / RPU-hour
            self.cost = 0.36 * self.redshift.rpus * self.runtime.seconds / 3600.0

        return stat # finalized state


class Query(Execute):
    DATA_STYLE = 'parquet'

    def query(self):
        self.out = os.path.join(self.redshift.output,
                                "results",
                                str(random.random()) + ".")
        #query    = f"unload ({repr(self.sql)}) to {repr(self.out)} " + \
        #           f"iam_role default " + \
        #           f"format as {self.DATA_STYLE} " + \
        #           f"manifest"

        query = f"""
create temp table temp_data as {self.sql};
unload ('select * from temp_data') to {repr(self.out)}
iam_role default
format as {self.DATA_STYLE}
manifest;
drop table temp_data;
"""
        print(query)
        return query


    def manifest_files(self):
        if self.files:
            return self.files

        status = self.finish()

        if status == "FINISHED":
            if self.info_cache['ResultRows'] != 0:
                # Because we're using `UNLOAD`, we get a manifest of the files
                # that make up our data.
                manif = self.out + "manifest"
                tmp   = self.handler.s3.download(manif)
                with open(tmp, "r") as f:
                    js = json.load(f)

                # Filter empty strings
                self.files = [e['url'].strip() for e in js['entries'] if e['url'].strip()]
            else: # no results returned, so no manifest file was created
                self.files = []

            return self.files
        else:
            return status # canceled or error


    def results(self):
        # if it's not a list, then we've failed
        if type(self.manifest_files()) != type([]):
            raise Exception(f"""Query has status {self.status()} did not complete and
                            thus has no results""")

        self.temps = [self.handler.s3.download(f) for f in self.manifest_files()]
        #local      = parallel_map(self.handler.s3.download, self.manifest_files())
        self.ds    = pa.dataset.dataset(self.temps)
        return self.ds


    # Return scalar results
    # Abstracts away a bunch of keystrokes
    def scalar(self):
        return self.results().head(1)[0][0].as_py()


    def __enter__(self):
        return self


    def __exit__(self, exception_type, exception_value, exception_traceback):
        self.close()


    def close(self):
        if self.temps:
            for file in self.temps:
                os.remove(file)