// mqtt2db -- subscries to MQTT topics and writes to a database
// Copyright (C) 2021-2022 Brian Tarricone <brian@tarricone.org>
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

use log::LevelFilter;
use serde::Deserialize;
use serde_yaml::from_str;
use std::io::Read;
use std::{collections::HashMap, fs::File, path::Path, time::Duration};

use crate::value::ValueType;

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase", untagged)]
pub enum MqttAuth {
    #[serde(rename_all = "camelCase")]
    UserPass { username: String, password: String },
    #[serde(rename_all = "camelCase")]
    Certificate {
        cert_file: String,
        private_key_file: String,
    },
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct MqttConfig {
    pub host: String,
    pub port: u16,
    pub client_id: String,
    pub auth: Option<MqttAuth>,
    pub ca_file: Option<String>,
    pub connect_timeout: Option<Duration>,
    pub keep_alive: Option<Duration>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct TagValue {
    pub r#type: ValueType,
    pub value: String,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct UserAuth {
    pub username: String,
    pub password: String,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "kebab-case", tag = "type")]
pub enum Database {
    #[serde(rename_all = "camelCase")]
    Influxdb {
        url: String,
        auth: Option<UserAuth>,
        db_name: String,
        measurement: String,
    },
}

#[derive(Debug, Deserialize, Clone)]
#[serde(rename_all = "kebab-case", tag = "type")]
pub enum Payload {
    #[serde(rename_all = "camelCase")]
    Json {
        value_field_path: String,
        timestamp_field_path: Option<String>,
    },
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Mapping {
    pub topic: String,
    pub payload: Option<Payload>,
    pub field_name: String,
    pub value_type: ValueType,
    pub tags: HashMap<String, TagValue>,
}

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Config {
    pub log_level: Option<LevelFilter>,
    pub mqtt: MqttConfig,
    pub databases: Vec<Database>,
    pub mappings: Vec<Mapping>,
}

impl Config {
    pub fn parse<P: AsRef<Path>>(filename: P) -> anyhow::Result<Config> {
        let mut f = File::open(filename)?;
        let mut contents = String::new();
        f.read_to_string(&mut contents)?;
        let config: Config = from_str(&contents)?;
        Ok(config)
    }
}