datahuborg/datahub

import json
from django.http import HttpResponse

from core.db.manager import DataHubManager
from django.contrib.auth.decorators import login_required

'''
Returns a successful JSON response.

@param json_dict - A dictionary representing the JSON to be sent to the user.
                   It will be augmented with the property,
                   json_dict.success = true

@return An HttpResponse representing the json_dict (augmented with the
        "success" property).
'''


def json_response(json_dict):
    json_dict["success"] = True
    return HttpResponse(json.dumps(json_dict),
                        content_type="application/json")

'''
Returns a failure JSON response.

@return An HttpResponse representing the JSON object
{
    "success": false
}
'''


def error_response():
    return HttpResponse(json.dumps({"success": False}),
                        content_type="application/json")

'''
Return the repos associated with this user.

@param manager - A DataHubManager object associated with the current user.

@return a list of the repo names associated with the current user, or None if
        there is an error.
'''


def get_repos(manager):
    repos = manager.list_repos()
    if len(repos) > 0:
        return repos
    return None

'''
Return the tables in a repo associated with this user.

@param manager - A DataHubManager object associated with the current user.
@param repo_name - The name of the repo, the user must be associated with this
                   repo.

@return a list of the tables in the repo with name = repo_name.
'''


def get_tables(manager, repo_name):
    tables = manager.list_tables(repo_name)
    if len(tables) > 0:
        return tables
    return None

'''
Return the list of repos associated with the current user.
If successful, the response is JSON of the form:

{
    "success": true,
    "repos": [String]
}

If there was a failure, the response is JSON of the form:

{
    "success": false
}
'''


@login_required
def repos(request):
    username = request.user.get_username()
    manager = DataHubManager(username)
    repos = get_repos(manager)
    if repos is not None:
        return json_response({"repos": repos})
    return error_response()

'''
Return the list of tables in the repo associated with the current user.
If successful, the response is JSON of the form:

{
    "success": true,
    "tables": [String]
}

If there was a failure, the response is JSON of the form:

{
    "success": false
}
'''


@login_required
def tables(request, repo_name):
    username = request.user.get_username()
    manager = DataHubManager(username)
    repos = get_repos(manager)
    if repos is not None and repo_name in repos:
        tables = get_tables(manager, repo_name)
        if tables is not None:
            return json_response({"tables": tables})
    return error_response()

'''
Return the schema for the table in the given repo associated with the current
user. If successful, the response is JSON of the form:

{
    "success": true,
    "schema": [[<field_name>String, <field_type>String]]
}

If there was a failure, the response is JSON of the form:

{
    "success": false
}
'''


@login_required
def schema(request, repo_name, table_name):
    username = request.user.get_username()
    manager = DataHubManager(username)
    repos = get_repos(manager)
    if repos is not None and repo_name in repos:
        tables = get_tables(manager, repo_name)
        if tables is not None and table_name in tables:
            schema = manager.get_schema(repo_name, table_name)
            if len(schema) > 0:
                return json_response({"schema": schema})
    return error_response()