#!/usr/bin/env python3
from __future__ import print_function
import sys
import os
import platform

from pyenliven import (
    echo0,
)


me = os.path.basename(__file__)
myDir = os.path.dirname(os.path.abspath(__file__))
defaultVirtualReposDir = myDir


def usage():
    echo0("Usage:")
    sys.stderr.write("Specify a branch")
    parent = "Bucket_Game-branches"
    if os.path.isdir(parent):
        echo0(" from Bucket_Game-branches:")
        for sub in os.listdir(parent):
            subPath = os.path.join(parent, sub)
            if sub.startswith("."):
                continue
            if os.path.isdir(subPath):
                echo0(subPath)
    else:
        echo0(" from Bucket_Game-branches.")

    echo0("{} <branch name (see above)> [<bucket_game path>]".format(me))
    echo0("")


profile = None
if platform.system() == "Windows":
    profile = os.environ.get('USERPROFILE')
    if profile is None:
        echo0("Error: USERPROFILE is not set.")
        sys.exit(1)
else:
    profile = os.environ.get('HOME')
    if profile is None:
        echo0("Error: HOME is not set.")
        sys.exit(1)

minetestPath = os.path.join(profile, "minetest")
gamesPath = os.path.join(minetestPath, "games")
defaultGamePath = None


def compareBranch(branchName, gamePath=None, bgVersion=None,
                  bgVersionsPath=minetestPath, compareOld=False,
                  branchesPath=None,
                  vReposDir=defaultVirtualReposDir):
    results = {}
    '''
    Keyword arguments:
    gamePath -- Specify a bucket_game base path to which to compare.
    bgVersion -- Specify a bucket_game version that is stored outside
        of the games directory but directly in bgVersionsPath (If
        bgVersion is not None, the function will fail if the directory
        "bucket_game-{}".format(bgVersion) doesn't exist in
        bgVersionsPath.
    compareOld: Set to True to use
        patchesDir = os.path.join(myDir, "Bucket_Game-base")
        instead of
        patchesDir = os.path.join(myDir, "Bucket_Game-branches")
        (The option is ignored if branchesPath is set).
    branchesPath -- Specify what directory contains the head branches.
    vReposDir -- Specify what directory contains
        Bucket_Game-branches and Bucket_Game-base (The option is ignored
        if branchesPath is set).

    Raises:
    - ValueError if the bgVersion is neither specified nor detected
      after "-vs-" in the patch name.
    - ValueError if the bgVersion directory isn't found
    - ValueError if the branch isn't found
    '''
    detectedBGVer = None
    parts = branchName.split("-")
    versionMsg = "specified"
    if (len(parts) > 2) and (parts[-2] == "vs"):
        detectedBGVer = parts[-1]
    if os.path.sep in branchName:
        branchName = os.path.split(branchName)[1]

    myDirSlash = myDir + os.path.sep

    if bgVersion is not None:
        if detectedBGVer is not None:
            print("WARNING: detected version {} but you specified {}"
                  "".format(detectedBGVer, bgVersion))
    else:
        bgVersion = detectedBGVer
        versionMsg = "detected"
    if compareOld:
        if bgVersion is None:
            raise ValueError("The game version was neither specified "
                             " nor after \"-vs-\" in the patch name.")

        detectedGame = "bucket_game-{}".format(bgVersion)
        # os.path.join(bgVersionsPath, detected)
        detectedPath = os.path.join(bgVersionsPath, detected)
        if not os.path.isdir(detectedPath):
            usage()
            raise ValueError("The {} game version is not present at"
                             " {}".format(versionMsg, detectedPath))

    if branchesPath is None:
        if compareOld:
            branchesPath = os.path.join(vReposDir,
                                        "Bucket_Game-base")
        else:
            branchesPath = os.path.join(vReposDir,
                                        "Bucket_Game-branches")
    if gamePath is None:
        if compareOld:
            gamePath = detectedPath
            basePath = detectedPath
        else:
            tryGame = "bucket_game"
            tryGamePath = os.path.join(gamesPath, tryGame)
            if not os.path.isdir(tryGamePath):
                tryGame = "Bucket_Game"
                tryGamePath = os.path.join(gamesPath, tryGame)
            gamePath = tryGamePath
            basePath = os.path.join(vReposDir, "Bucket_Game-base",
                                    branchName)
            basePath = os.path.realpath(basePath)

    if not os.path.isdir(gamePath):
        usage()
        raise ValueError("The {} game version is not present at"
                         " {}".format(versionMsg, gamePath))

    branchPath = os.path.join(branchesPath, branchName)
    if not os.path.isdir(branchPath):
        raise ValueError("The branch wasn't found at \"{}\""
                         "".format(branchPath))
    branchPath = os.path.realpath(branchPath)

    basePathRel = basePath
    if basePathRel.startswith(myDirSlash):
        basePathRel = basePathRel[len(myDirSlash):]

    gamePathRel = gamePath
    if gamePathRel.startswith(myDirSlash):
        gamePathRel = gamePathRel[len(myDirSlash):]

    branchPathRel = branchPath
    if branchPathRel.startswith(myDirSlash):
        branchPathRel = branchPathRel[len(myDirSlash):]

    print("meld \"{}\" \"{}\"".format(gamePath, branchPath))
    patchFilePath = branchPath+".patch"
    print("diff -ru \"{}\" \"{}\" > \"{}\""
          "".format(basePathRel, branchPathRel, patchFilePath))

    results = {
        'gamePath': gamePath,
        'branchPath': branchPath,
        'patchFilePath': patchFilePath,
    }
    return results


def main():
    global defaultGamePath
    defaultGamePath = None
    if len(sys.argv) < 2:
        usage()
        echo0("Error: You must provide a branch name.\n")
        return 1
    if len(sys.argv) > 3:
        usage()
        echo0("Error: There are too many arguments: {}.\n"
              "".format(sys.argv))
        return 1
    if len(sys.argv) > 2:
        defaultGamePath = sys.argv[2]

    results = compareBranch(sys.argv[1], gamePath=defaultGamePath)
    echo0("# ^ Do that to see the difference or generate a patch,"
          " but the first directory must be unmodified from the"
          " original release package.")
    return 0


if __name__ == "__main__":
    sys.exit(main())