#!/usr/bin/env python
# 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/.

import json
import re
import sys
import toml
import voluptuous
import voluptuous.humanize
from voluptuous import Schema, Optional, Any, All, Required, Length, Range, Msg, Match


Text = Any(str, bytes)


id_regex = re.compile(r"^[a-z0-9-]+$")
feature_schema = Schema(
    {
        Match(id_regex): {
            Required("title"): All(Text, Length(min=1)),
            Required("description"): All(Text, Length(min=1)),
            Required("bug-numbers"): All(Length(min=1), [All(int, Range(min=1))]),
            Required("restart-required"): bool,
            Required("type"): "boolean",  # In the future this may include other types
            Optional("preference"): Text,
            Optional("default-value"): Any(
                bool, dict
            ),  # the types of the keys here should match the value of `type`
            Optional("is-public"): Any(bool, dict),
            Optional("description-links"): dict,
        },
    }
)


EXIT_OK = 0
EXIT_ERROR = 1


def main(output, *filenames):
    features = {}
    errors = False
    try:
        features = process_files(filenames)
        json.dump(features, output, sort_keys=True)
    except ExceptionGroup as error_group:
        print(str(error_group))
        return EXIT_ERROR
    return EXIT_OK


class ExceptionGroup(Exception):
    def __init__(self, errors):
        self.errors = errors

    def __str__(self):
        rv = ["There were errors while processing feature definitions:"]
        for error in self.errors:
            # indent the message
            s = "\n".join("    " + line for line in str(error).split("\n"))
            # add a * at the beginning of the first line
            s = "  * " + s[4:]
            rv.append(s)
        return "\n".join(rv)


class FeatureGateException(Exception):
    def __init__(self, message, filename=None):
        super(FeatureGateException, self).__init__(message)
        self.filename = filename

    def __str__(self):
        message = super(FeatureGateException, self).__str__()
        rv = ["In"]
        if self.filename is None:
            rv.append("unknown file:")
        else:
            rv.append('file "{}":\n'.format(self.filename))
        rv.append(message)
        return " ".join(rv)

    def __repr__(self):
        # Turn "FeatureGateExcept(<message>,)" into "FeatureGateException(<message>, filename=<filename>)"
        original = super(FeatureGateException, self).__repr__()
        with_comma = original[:-1]
        # python 2 adds a trailing comma and python 3 does not, so we need to conditionally reinclude it
        if len(with_comma) > 0 and with_comma[-1] != ",":
            with_comma = with_comma + ","
        return with_comma + " filename={!r})".format(self.filename)


def process_files(filenames):
    features = {}
    errors = []

    for filename in filenames:
        try:
            with open(filename, "r") as f:
                feature_data = toml.load(f)

            voluptuous.humanize.validate_with_humanized_errors(
                feature_data, feature_schema
            )

            for feature_id, feature in feature_data.items():
                feature["id"] = feature_id
                features[feature_id] = expand_feature(feature)
        except (
            voluptuous.error.Error,
            IOError,
            FeatureGateException,
            toml.TomlDecodeError,
        ) as e:
            # Wrap errors in enough information to know which file they came from
            errors.append(FeatureGateException(e, filename))

    if errors:
        raise ExceptionGroup(errors)

    return features


def hyphens_to_camel_case(s):
    """Convert names-with-hyphens to namesInCamelCase"""
    rv = ""
    for part in s.split("-"):
        if rv == "":
            rv = part.lower()
        else:
            rv += part[0].upper() + part[1:].lower()
    return rv


def expand_feature(feature):
    """Fill in default values for optional fields"""

    # convert all names-with-hyphens to namesInCamelCase
    key_changes = []
    for key in feature.keys():
        if "-" in key:
            new_key = hyphens_to_camel_case(key)
            key_changes.append((key, new_key))

    for old_key, new_key in key_changes:
        feature[new_key] = feature[old_key]
        del feature[old_key]

    if feature["type"] == "boolean":
        feature.setdefault("preference", "features.{}.enabled".format(feature["id"]))
        # set default value to None so that we can test for perferences where we forgot to set the default value
        feature.setdefault("defaultValue", None)
    elif "preference" not in feature:
        raise FeatureGateException(
            "Features of type {} must specify an explicit preference name".format(
                feature["type"]
            )
        )

    feature.setdefault("isPublic", False)

    try:
        for key in ["defaultValue", "isPublic"]:
            feature[key] = process_configured_value(key, feature[key])
    except FeatureGateException as e:
        raise FeatureGateException(
            "Error when processing feature {}: {}".format(feature["id"], e)
        )

    return feature


def process_configured_value(name, value):
    if not isinstance(value, dict):
        return {"default": value}

    if "default" not in value:
        raise FeatureGateException(
            "Config for {} has no default: {}".format(name, value)
        )

    expected_keys = set(
        {
            "default",
            "win",
            "mac",
            "linux",
            "android",
            "nightly",
            "early_beta_or_earlier",
            "beta",
            "release",
            "dev-edition",
            "esr",
            "thunderbird",
        }
    )

    for key in value.keys():
        parts = [p.strip() for p in key.split(",")]
        for part in parts:
            if part not in expected_keys:
                raise FeatureGateException(
                    "Unexpected target {}, expected any of {}".format(
                        part, expected_keys
                    )
                )

    # TODO Compute values at build time, so that it always returns only a single value.

    return value


if __name__ == "__main__":
    sys.exit(main(sys.stdout, *sys.argv[1:]))