# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
from __future__ import absolute_import

import json
import re
import urllib2

from .symLogging import LogTrace, LogError

# Precompiled regex for validating lib names
# Empty lib name means client couldn't associate frame with any lib
gLibNameRE = re.compile("[0-9a-zA-Z_+\-\.]*$")

# Maximum number of times a request can be forwarded to a different server
# for symbolication. Also prevents loops.
MAX_FORWARDED_REQUESTS = 3

"""
Symbolication is broken when using type 'str' in python 2.7, so we use 'basestring'.
But for python 3.0 compatibility, 'basestring' isn't defined, but the 'str' type works.
So we force 'basestring' to 'str'.
"""
try:
    basestring
except NameError:
    basestring = str


class ModuleV3:

    def __init__(self, libName, breakpadId):
        self.libName = libName
        self.breakpadId = breakpadId


def getModuleV3(libName, breakpadId):
    if not isinstance(libName, basestring) or not gLibNameRE.match(libName):
        LogTrace("Bad library name: " + str(libName))
        return None

    if not isinstance(breakpadId, basestring):
        LogTrace("Bad breakpad id: " + str(breakpadId))
        return None

    return ModuleV3(libName, breakpadId)


class SymbolicationRequest:

    def __init__(self, symFileManager, rawRequests):
        self.Reset()
        self.symFileManager = symFileManager
        self.stacks = []
        self.combinedMemoryMap = []
        self.knownModules = []
        self.symbolSources = []
        self.ParseRequests(rawRequests)

    def Reset(self):
        self.symFileManager = None
        self.isValidRequest = False
        self.combinedMemoryMap = []
        self.knownModules = []
        self.stacks = []
        self.forwardCount = 0

    def ParseRequests(self, rawRequests):
        self.isValidRequest = False

        try:
            if not isinstance(rawRequests, dict):
                LogTrace("Request is not a dictionary")
                return

            if "version" not in rawRequests:
                LogTrace("Request is missing 'version' field")
                return
            version = rawRequests["version"]
            if version != 4:
                LogTrace("Invalid version: %s" % version)
                return

            if "forwarded" in rawRequests:
                if not isinstance(rawRequests["forwarded"], (int, int)):
                    LogTrace("Invalid 'forwards' field: %s"
                             % rawRequests["forwarded"])
                    return
                self.forwardCount = rawRequests["forwarded"]

            # Client specifies which sets of symbols should be used
            if "symbolSources" in rawRequests:
                try:
                    sourceList = [x.upper()
                                  for x in rawRequests["symbolSources"]]
                    for source in sourceList:
                        if source in self.symFileManager\
                                .sOptions["symbolPaths"]:
                            self.symbolSources.append(source)
                        else:
                            LogTrace("Unrecognized symbol source: " + source)
                            continue
                except:
                    self.symbolSources = []
                    pass

            if not self.symbolSources:
                self.symbolSources.append(
                    self.symFileManager.sOptions["defaultApp"])
                self.symbolSources.append(
                    self.symFileManager.sOptions["defaultOs"])

            if "memoryMap" not in rawRequests:
                LogTrace("Request is missing 'memoryMap' field")
                return
            memoryMap = rawRequests["memoryMap"]
            if not isinstance(memoryMap, list):
                LogTrace("'memoryMap' field in request is not a list")

            if "stacks" not in rawRequests:
                LogTrace("Request is missing 'stacks' field")
                return
            stacks = rawRequests["stacks"]
            if not isinstance(stacks, list):
                LogTrace("'stacks' field in request is not a list")
                return

            # Check memory map is well-formatted
            cleanMemoryMap = []
            for module in memoryMap:
                if not isinstance(module, list):
                    LogTrace(
                        "Entry in memory map is not a list: " + str(module))
                    return

                if len(module) != 2:
                    LogTrace("Entry in memory map is not a 2 item list: " +
                             str(module))
                    return
                module = getModuleV3(*module)

                if module is None:
                    return

                cleanMemoryMap.append(module)

            self.combinedMemoryMap = cleanMemoryMap
            self.knownModules = [False] * len(self.combinedMemoryMap)

            # Check stack is well-formatted
            for stack in stacks:
                if not isinstance(stack, list):
                    LogTrace("stack is not a list")
                    return
                for entry in stack:
                    if not isinstance(entry, list):
                        LogTrace("stack entry is not a list")
                        return
                    if len(entry) != 2:
                        LogTrace("stack entry doesn't have exactly 2 elements")
                        return

                self.stacks.append(stack)

        except Exception as e:
            LogTrace("Exception while parsing request: " + str(e))
            return

        self.isValidRequest = True

    def ForwardRequest(self, indexes, stack, modules, symbolicatedStack):
        LogTrace("Forwarding " + str(len(stack)) + " PCs for symbolication")

        try:
            url = self.symFileManager.sOptions["remoteSymbolServer"]
            rawModules = []
            moduleToIndex = {}
            newIndexToOldIndex = {}
            for moduleIndex, m in modules:
                l = [m.libName, m.breakpadId]
                newModuleIndex = len(rawModules)
                rawModules.append(l)
                moduleToIndex[m] = newModuleIndex
                newIndexToOldIndex[newModuleIndex] = moduleIndex

            rawStack = []
            for entry in stack:
                moduleIndex = entry[0]
                offset = entry[1]
                module = self.combinedMemoryMap[moduleIndex]
                newIndex = moduleToIndex[module]
                rawStack.append([newIndex, offset])

            requestVersion = 4
            while True:
                requestObj = {
                    "symbolSources": self.symbolSources,
                    "stacks": [rawStack],
                    "memoryMap": rawModules,
                    "forwarded": self.forwardCount + 1,
                    "version": requestVersion
                }
                requestJson = json.dumps(requestObj)
                headers = {"Content-Type": "application/json"}
                requestHandle = urllib2.Request(url, requestJson, headers)
                try:
                    response = urllib2.urlopen(requestHandle)
                except Exception as e:
                    if requestVersion == 4:
                        # Try again with version 3
                        requestVersion = 3
                        continue
                    raise e
                succeededVersion = requestVersion
                break

        except Exception as e:
            LogError("Exception while forwarding request: " + str(e))
            return

        try:
            responseJson = json.loads(response.read())
        except Exception as e:
            LogError("Exception while reading server response to forwarded"
                     " request: " + str(e))
            return

        try:
            if succeededVersion == 4:
                responseKnownModules = responseJson['knownModules']
                for newIndex, known in enumerate(responseKnownModules):
                    if known and newIndex in newIndexToOldIndex:
                        self.knownModules[newIndexToOldIndex[newIndex]] = True

                responseSymbols = responseJson['symbolicatedStacks'][0]
            else:
                responseSymbols = responseJson[0]
            if len(responseSymbols) != len(stack):
                LogError(str(len(responseSymbols)) + " symbols in response, " +
                         str(len(stack)) + " PCs in request!")
                return

            for index in range(0, len(stack)):
                symbol = responseSymbols[index]
                originalIndex = indexes[index]
                symbolicatedStack[originalIndex] = symbol
        except Exception as e:
            LogError("Exception while parsing server response to forwarded"
                     " request: " + str(e))
            return

    def Symbolicate(self, stackNum):
        # Check if we should forward requests when required sym files don't
        # exist
        shouldForwardRequests = False
        if self.symFileManager.sOptions["remoteSymbolServer"] and \
                self.forwardCount < MAX_FORWARDED_REQUESTS:
            shouldForwardRequests = True

        # Symbolicate each PC
        pcIndex = -1
        symbolicatedStack = []
        missingSymFiles = []
        unresolvedIndexes = []
        unresolvedStack = []
        unresolvedModules = []
        stack = self.stacks[stackNum]

        for moduleIndex, module in enumerate(self.combinedMemoryMap):
            if not self.symFileManager.GetLibSymbolMap(module.libName,
                                                       module.breakpadId,
                                                       self.symbolSources):
                missingSymFiles.append((module.libName, module.breakpadId))
                if shouldForwardRequests:
                    unresolvedModules.append((moduleIndex, module))
            else:
                self.knownModules[moduleIndex] = True

        for entry in stack:
            pcIndex += 1
            moduleIndex = entry[0]
            offset = entry[1]
            if moduleIndex == -1:
                symbolicatedStack.append(hex(offset))
                continue
            module = self.combinedMemoryMap[moduleIndex]

            if (module.libName, module.breakpadId) in missingSymFiles:
                if shouldForwardRequests:
                    unresolvedIndexes.append(pcIndex)
                    unresolvedStack.append(entry)
                symbolicatedStack.append(
                    hex(offset) + " (in " + module.libName + ")")
                continue

            functionName = None
            libSymbolMap = self.symFileManager.GetLibSymbolMap(
                module.libName,
                module.breakpadId,
                self.symbolSources
            )
            functionName = libSymbolMap.Lookup(offset)

            if functionName is None:
                functionName = hex(offset)
            symbolicatedStack.append(
                functionName + " (in " + module.libName + ")")

        # Ask another server for help symbolicating unresolved addresses
        if len(unresolvedStack) > 0 or len(unresolvedModules) > 0:
            self.ForwardRequest(unresolvedIndexes, unresolvedStack,
                                unresolvedModules, symbolicatedStack)

        return symbolicatedStack
