import sys, json, calendar, time
from dbaccess import execQuery, database
from misc import (
    textToId, idToText, getContext, getTimestampFromContext, getSnapshots,
    benchmarkToComponents, printJSONHeader)



# Gets the top changes for a specific context by considering only the
# last change in each time series.
#
# An additional filter is applied by only considering results from
# test cases matching test_case_ids.
#
# NOTE: The result may contain at most one change from a given time series.
def getTopChangesForContext_last(
    host_id, platform_id, branch_id, regressions, premature, limit,
    test_case_ids):

    query = (
        "SELECT change.benchmarkId, change.metricId, sha1Id, last_timestamp, ")
    query += ("greatest(score, premature_score)" if premature else "score")
    query += (
        "    AS final_score"
        "  FROM"
        "   (SELECT benchmarkId, metricId, max(timestamp) AS last_timestamp"
        "      FROM change"
        "     WHERE hostId = %s"
        "       AND platformId = %s"
        "       AND branchId = %s"
        "       AND regression = %s")
    args = [host_id, platform_id, branch_id, regressions]

    if len(test_case_ids) > 0:
        query += (
            "   AND testCaseId IN (%s" + ", %s"*(len(test_case_ids) - 1) + ")"
            )
        args += test_case_ids

    query += (
        "     GROUP BY benchmarkId, metricId) AS last_change"
        " , change"
        " WHERE last_change.benchmarkId = change.benchmarkId"
        "   AND last_change.metricId = change.metricId"
        "   AND change.timestamp = last_timestamp"
        " ORDER BY final_score DESC, last_timestamp DESC"
        " LIMIT %s"
        )
    args.append(limit)

    return execQuery(query, args)


# Gets the top changes for a specific context by considering all
# changes in the given time scope.
#
# An additional filter is applied by only considering results from
# test cases matching test_case_ids.
#
# NOTE: The result may contain any number of changes from a given time
# series.
def getTopChangesForContext_timeScope(
    host_id, platform_id, branch_id, regressions, premature, limit,
    test_case_ids, lo_timestamp):

    query = "SELECT benchmarkId, metricId, sha1Id, timestamp, "
    query += ("greatest(score, premature_score)" if premature else "score")
    query += (
        "    AS final_score"
        "  FROM change"
        " WHERE hostId = %s"
        "   AND platformId = %s"
        "   AND branchId = %s"
        "   AND regression = %s"
        "   AND timestamp >= %s")
    args = [host_id, platform_id, branch_id, regressions, lo_timestamp]

    if len(test_case_ids) > 0:
        query += (
            "   AND testCaseId IN (%s" + ", %s"*(len(test_case_ids) - 1) + ")"
            )
        args += test_case_ids

    query += (
        " ORDER BY final_score DESC, timestamp DESC"
        " LIMIT %s"
        )
    args.append(limit)

    return execQuery(query, args)


# Returns test case IDs corresponding to the names in test_case_filter.
def getTestCaseIdsFromFilter(test_case_filter):
    return (execQuery(
        "SELECT id FROM testCase"
        " WHERE value IN (%s" + ", %s"*(len(test_case_filter) - 1) + ")",
        tuple(test_case_filter))
            if ((test_case_filter != None) and (len(test_case_filter) > 0))
            else ())


class GetTopChanges:

    def __init__(
        self, test_case_filter, regressions, last, timescope, premature, limit):
        self.test_case_filter = test_case_filter
        self.regressions = regressions
        self.last = last
        self.timescope = timescope
        self.premature = premature
        self.limit = limit


    # Gets the top changes for a specific context.
    def getTopChangesForContext(
        self, host_id, platform_id, branch_id, lo_timestamp):

        test_case_ids = getTestCaseIdsFromFilter(self.test_case_filter)

        return (
            getTopChangesForContext_last(
                host_id, platform_id, branch_id, self.regressions,
                self.premature, self.limit, test_case_ids)
            if self.last else
            getTopChangesForContext_timeScope(
                host_id, platform_id, branch_id, self.regressions,
                self.premature, self.limit, test_case_ids, lo_timestamp)
            )


    # Gets the top changes for all contexts.
    def getTopChangesForAllContexts(self):

        # Compute lowest timestamp (secs since 1970) in time scope (days ago):
        curr_timestamp = calendar.timegm(time.gmtime())
        secs_in_day = 24 * 60 * 60
        lo_timestamp  = (
            -1 if (self.timescope < 0) else
             curr_timestamp - self.timescope * secs_in_day)

        context_ids = execQuery(
            "SELECT DISTINCT hostId, platformId, branchId FROM context "
            "ORDER BY hostId, platformId, branchId", ())

        contexts = []

        for host_id, platform_id, branch_id in context_ids:
            top_changes = self.getTopChangesForContext(
                host_id, platform_id, branch_id, lo_timestamp)
            contexts.append({
                    "hostId": host_id,
                    "platformId": platform_id,
                    "branchId": branch_id,
                    "topchanges": top_changes
                    })

        return contexts


    def execute(self):
        self.contexts = self.getTopChangesForAllContexts()
        self.writeOutput()


    def writeOutputAsJSON(self):
        printJSONHeader()
        json.dump({
                'database': database(),
                'regressions': self.regressions,
                'last': self.last,
                'timescope': self.timescope,
                'premature': self.premature,
                'limit': self.limit,
                'contexts': self.contexts
                }, sys.stdout)


class GetTopChangesAsJSON(GetTopChanges):
    def writeOutput(self):
        self.writeOutputAsJSON()