import sys
import json

from dbaccess import execQuery
from misc import idToText, printJSONHeader

class ListContexts:

    def __init__(self, ranked_only):
        self.ranked_only = ranked_only


    def rankingsExist(self, contextId):
        rankings = execQuery(
            "SELECT id FROM ranking WHERE context2Id = %s LIMIT 1",
            (contextId,))
        return len(rankings) > 0


    def execute(self):

        # Get all host/platform/branch/sha1 combinations:
        contexts = execQuery(
                "SELECT id, hostId, platformId, branchId, sha1Id,"
                " EXTRACT(EPOCH FROM timestamp)::INT"
                " FROM context"
                " ORDER BY hostId, platformId,"
                " branchId, timestamp DESC;", ()) \
                + [(-1, -1, -1, -1, -1, -1)] # Sentinel value

        self.contexts = []

        if not len(contexts):
            return

        id, host, platform, branch, sha1, timestamp = contexts[0]

        curHost, curPlatform, curBranch = host, platform, branch

        rankings_exist = self.rankingsExist(id)
        rankings_exist_count = 1 if rankings_exist else 0

        curSnapshots = []
        if (not self.ranked_only) or rankings_exist:
            curSnapshots = [
                (idToText('sha1', sha1), timestamp, 1 if rankings_exist else 0)]

        for (id, host, platform, branch, sha1, timestamp) in contexts[1:]:
            if (host, platform, branch) != (curHost, curPlatform, curBranch):
                if (not self.ranked_only) or (rankings_exist_count > 0):
                    assert len(curSnapshots) > 0
                    self.contexts.append({
                            'host' :        idToText('host', curHost),
                            'platform' :    idToText('platform', curPlatform),
                            'branch' :      idToText('branch', curBranch),
                            'snapshots' :   curSnapshots
                            })

                rankings_exist_count = 0
                curHost, curPlatform, curBranch = host, platform, branch
                curSnapshots = []

            rankings_exist = self.rankingsExist(id)
            if rankings_exist:
                rankings_exist_count = rankings_exist_count + 1
            if (not self.ranked_only) or rankings_exist:
                curSnapshots.append(
                    (idToText('sha1', sha1), timestamp,
                     1 if rankings_exist else 0))

        self.writeOutput()

    def writeOutputAsJSON(self):
        printJSONHeader()
        json.dump({ 'contexts' : self.contexts }, sys.stdout)

class ListContextsAsJSON(ListContexts):
    def writeOutput(self):
        self.writeOutputAsJSON()