servo/components/devtools/actors/preference.rs

/* 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 https://mozilla.org/MPL/2.0/. */

use std::collections::HashMap;
use std::net::TcpStream;

use serde::Serialize;
use serde_json::{Map, Value};
use servo_config::pref_util::PrefValue;
use servo_config::prefs::pref_map;

use crate::actor::{Actor, ActorMessageStatus, ActorRegistry};
use crate::protocol::JsonPacketStream;
use crate::StreamId;

pub struct PreferenceActor {
    name: String,
}

impl PreferenceActor {
    pub fn new(name: String) -> Self {
        Self { name }
    }
}

impl Actor for PreferenceActor {
    fn name(&self) -> String {
        self.name.clone()
    }

    fn handle_message(
        &self,
        _registry: &ActorRegistry,
        msg_type: &str,
        msg: &Map<String, Value>,
        stream: &mut TcpStream,
        _id: StreamId,
    ) -> Result<ActorMessageStatus, ()> {
        let mut key = msg.get("value").unwrap().as_str().unwrap();

        // Mapping to translate a Firefox preference name onto the corresponding Servo preference name
        let pref_name_mapping: HashMap<&str, &str> =
            [("dom.serviceWorkers.enabled", "dom.serviceworker.enabled")]
                .iter()
                .copied()
                .collect();
        if pref_name_mapping.contains_key(key) {
            key = pref_name_mapping.get(key).unwrap();
        }

        let pref_value = pref_map().get(key);
        Ok(handle_preference_value(
            pref_value,
            self.name(),
            msg_type,
            stream,
        ))
    }
}

fn handle_preference_value(
    pref_value: PrefValue,
    name: String,
    msg_type: &str,
    stream: &mut TcpStream,
) -> ActorMessageStatus {
    match pref_value {
        PrefValue::Float(value) => {
            let reply = FloatReply { from: name, value };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },
        PrefValue::Int(value) => {
            let reply = IntReply { from: name, value };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },
        PrefValue::Str(value) => {
            let reply = CharReply { from: name, value };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },
        PrefValue::Bool(value) => {
            let reply = BoolReply { from: name, value };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },
        PrefValue::Array(values) => {
            let mut result = ActorMessageStatus::Processed;
            for value in values {
                result = handle_preference_value(value, name.clone(), msg_type, stream);
            }
            result
        },
        PrefValue::Missing => handle_missing_preference(name, msg_type, stream),
    }
}

// if the preferences are missing from pref_map then we return a
// fake preference response based on msg_type.
fn handle_missing_preference(
    name: String,
    msg_type: &str,
    stream: &mut TcpStream,
) -> ActorMessageStatus {
    match msg_type {
        "getBoolPref" => {
            let reply = BoolReply {
                from: name,
                value: false,
            };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },

        "getCharPref" => {
            let reply = CharReply {
                from: name,
                value: "".to_owned(),
            };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },

        "getIntPref" => {
            let reply = IntReply {
                from: name,
                value: 0,
            };
            let _ = stream.write_json_packet(&reply);
            ActorMessageStatus::Processed
        },

        _ => ActorMessageStatus::Ignored,
    }
}

#[derive(Serialize)]
struct BoolReply {
    from: String,
    value: bool,
}

#[derive(Serialize)]
struct CharReply {
    from: String,
    value: String,
}

#[derive(Serialize)]
struct IntReply {
    from: String,
    value: i64,
}

#[derive(Serialize)]
struct FloatReply {
    from: String,
    value: f64,
}