# 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 yaml
import json
import sys
import jsonschema
import pathlib

HEADER_LINE = (
    "// This file was generated by generate_feature_manifest.py from FeatureManifest.yaml."
    " DO NOT EDIT.\n"
)

FEATURE_MANIFEST_SCHEMA = pathlib.Path(
    "schemas", "ExperimentFeatureManifest.schema.json"
)

NIMBUS_FALLBACK_PREFS = (
    "constexpr std::pair<nsLiteralCString, nsLiteralCString>"
    "NIMBUS_FALLBACK_PREFS[]{{{}}};"
)

EXPORTED_SYMBOLS = 'const EXPORTED_SYMBOLS = ["{}"];'


def write_fm_cpp_headers(fd):
    fd.write(HEADER_LINE)


def write_fm_js_headers(fd):
    fd.write("\n".join([HEADER_LINE, EXPORTED_SYMBOLS.format("FeatureManifest")]))


def generate_feature_manifest(fd, input_file):
    write_fm_js_headers(fd)
    nimbus_dir_path = pathlib.Path(input_file).parent
    try:
        with open(input_file, "r", encoding="utf-8") as yaml_input:
            data = yaml.safe_load(yaml_input)
            with pathlib.Path(nimbus_dir_path, FEATURE_MANIFEST_SCHEMA).open() as f:
                schema = json.load(f)
                for feature_entry in data:
                    try:
                        jsonschema.validate(data[feature_entry], schema)
                    except Exception as e:
                        print("Error while validating FeatureManifest.yaml")
                        print("On key: {}".format(feature_entry))
                        print("Input file: {}".format(input_file))
                        raise e
            fd.write("const FeatureManifest = {};".format(json.dumps(data)))
    except (IOError) as e:
        print("{}: error:\n  {}\n".format(input_file, e))
        sys.exit(1)


def platform_feature_manifest_array(features):
    entries = []
    for (feature, featureData) in features.items():
        # Features have to be tagged isEarlyStartup to be accessible
        # to Nimbus platform API
        if not featureData.get("isEarlyStartup", False):
            continue
        entries.extend(
            '{{ "{}_{}"_ns, "{}"_ns }}'.format(
                feature, variable, variableData["fallbackPref"]
            )
            for (variable, variableData) in featureData.get("variables", {}).items()
            if variableData.get("fallbackPref", False)
        )
    return NIMBUS_FALLBACK_PREFS.format(", ".join(entries))


def generate_platform_feature_manifest(fd, input_file):
    write_fm_cpp_headers(fd)

    def file_structure(data):
        return "\n".join(
            [
                "#ifndef mozilla_NimbusFeaturesManifest_h",
                "#define mozilla_NimbusFeaturesManifest_h",
                "#include <utility>",
                '#include "mozilla/Maybe.h"',
                '#include "nsStringFwd.h"',
                "namespace mozilla {",
                platform_feature_manifest_array(data),
                '#include "./lib/NimbusFeatureManifest.inc.h"',
                "}  // namespace mozilla",
                "#endif  // mozilla_NimbusFeaturesManifest_h",
            ]
        )

    try:
        with open(input_file, "r", encoding="utf-8") as yaml_input:
            data = yaml.safe_load(yaml_input)
            fd.write(file_structure(data))
    except (IOError) as e:
        print("{}: error:\n  {}\n".format(input_file, e))
        sys.exit(1)