from __future__ import absolute_import


def to_chrome_path(path):
    path = path.replace("/locales/en-US", "")
    if path.startswith("./"):
        path = path[2:]
    return path


def get_dtd_path(name, dtds):
    return dtds[name[1:-1]]["file"]


def get_entity_name(s):
    return s[1:-1]


def ind(n=0):
    return " " * 4 * n


def add_copy(dtd, entity_id):
    result = "{ " + 'COPY("{0}", "{1}")'.format(dtd, entity_id) + " }\n"
    return result


def make_header():
    res = "# coding=utf8\n\n"
    res += "# Any copyright is dedicated to the Public Domain.\n"
    res += "# http://creativecommons.org/publicdomain/zero/1.0/\n\n"
    res += "from __future__ import absolute_import\n"
    res += "import fluent.syntax.ast as FTL\n"
    res += "from fluent.migrate.helpers import transforms_from\n"
    res += "from fluent.migrate.helpers import MESSAGE_REFERENCE, "
    res += "TERM_REFERENCE, VARIABLE_REFERENCE\n"
    res += "from fluent.migrate import COPY, CONCAT, REPLACE\n"

    return res


def build_migration(messages, dtds, data):
    res = make_header()
    desc = "Bug {0} - {1}, part {{index}}.".format(data["bug_id"], data["description"])
    res += '\n\ndef migrate(ctx):\n    """{0}"""\n\n'.format(desc)

    for dtd_path in data["dtd"]:
        res += "{0}ctx.maybe_add_localization('{1}')\n".format(
            ind(1), to_chrome_path(dtd_path)
        )

    res += "\n"
    res += ind(1) + "ctx.add_transforms(\n"
    res += ind(2) + "'{0}',\n".format(to_chrome_path(data["ftl"]))
    res += ind(2) + "'{0}',\n".format(to_chrome_path(data["ftl"]))
    res += ind(2) + "transforms_from(\n"
    res += '"""\n'
    for l10n_id in messages:
        msg = messages[l10n_id]
        if not msg["attrs"]:
            entity = get_entity_name(msg["value"])
            entity_path = to_chrome_path(get_dtd_path(msg["value"], dtds))
            res += "{0} = {1}".format(l10n_id, add_copy(entity_path, entity))
        else:
            res += "{0} = \n".format(l10n_id)
            for name in msg["attrs"]:
                attr = msg["attrs"][name]
                attr_name = get_entity_name(attr)
                entity_path = to_chrome_path(get_dtd_path(attr, dtds))
                res += "{0}.{1} = {2}".format(
                    ind(1), name, add_copy(entity_path, attr_name)
                )
    res += '"""\n'
    res += ind(2) + ")\n"
    res += ind(1) + ")"

    return res