// Copyright 2017-2019 int08h LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::env;
use std::time::Duration;

use crate::config::ServerConfig;
use crate::config::{DEFAULT_BATCH_SIZE, DEFAULT_STATUS_INTERVAL};
use crate::key::KmsProtection;
use crate::Error;

///
/// Obtain a Roughenough server configuration ([ServerConfig](trait.ServerConfig.html))
/// from environment variables.
///
///   Config parameter  | Environment Variable
///   ----------------  | --------------------
///   port              | `ROUGHENOUGH_PORT`
///   interface         | `ROUGHENOUGH_INTERFACE`
///   seed              | `ROUGHENOUGH_SEED`
///   batch_size        | `ROUGHENOUGH_BATCH_SIZE`
///   status_interval   | `ROUGHENOUGH_STATUS_INTERVAL`
///   kms_protection    | `ROUGHENOUGH_KMS_PROTECTION`
///   health_check_port | `ROUGHENOUGH_HEALTH_CHECK_PORT`
///   client_stats      | `ROUGHENOUGH_CLIENT_STATS`
///   fault_percentage  | `ROUGHENOUGH_FAULT_PERCENTAGE`
///
pub struct EnvironmentConfig {
    port: u16,
    interface: String,
    seed: Vec<u8>,
    batch_size: u8,
    status_interval: Duration,
    kms_protection: KmsProtection,
    health_check_port: Option<u16>,
    client_stats: bool,
    fault_percentage: u8,
}

const ROUGHENOUGH_PORT: &str = "ROUGHENOUGH_PORT";
const ROUGHENOUGH_INTERFACE: &str = "ROUGHENOUGH_INTERFACE";
const ROUGHENOUGH_SEED: &str = "ROUGHENOUGH_SEED";
const ROUGHENOUGH_BATCH_SIZE: &str = "ROUGHENOUGH_BATCH_SIZE";
const ROUGHENOUGH_STATUS_INTERVAL: &str = "ROUGHENOUGH_STATUS_INTERVAL";
const ROUGHENOUGH_KMS_PROTECTION: &str = "ROUGHENOUGH_KMS_PROTECTION";
const ROUGHENOUGH_HEALTH_CHECK_PORT: &str = "ROUGHENOUGH_HEALTH_CHECK_PORT";
const ROUGHENOUGH_CLIENT_STATS: &str = "ROUGHENOUGH_CLIENT_STATS";
const ROUGHENOUGH_FAULT_PERCENTAGE: &str = "ROUGHENOUGH_FAULT_PERCENTAGE";

impl EnvironmentConfig {
    pub fn new() -> Result<Self, Error> {
        let mut cfg = EnvironmentConfig {
            port: 0,
            interface: "".to_string(),
            seed: Vec::new(),
            batch_size: DEFAULT_BATCH_SIZE,
            status_interval: DEFAULT_STATUS_INTERVAL,
            kms_protection: KmsProtection::Plaintext,
            health_check_port: None,
            client_stats: false,
            fault_percentage: 0,
        };

        if let Ok(port) = env::var(ROUGHENOUGH_PORT) {
            cfg.port = port
                .parse()
                .unwrap_or_else(|_| panic!("invalid port: {}", port));
        };

        if let Ok(interface) = env::var(ROUGHENOUGH_INTERFACE) {
            cfg.interface = interface.to_string();
        };

        if let Ok(seed) = env::var(ROUGHENOUGH_SEED) {
            cfg.seed =
                hex::decode(&seed).expect("invalid seed value; 'seed' should be a hex value");
        };

        if let Ok(batch_size) = env::var(ROUGHENOUGH_BATCH_SIZE) {
            cfg.batch_size = batch_size
                .parse()
                .unwrap_or_else(|_| panic!("invalid batch_size: {}", batch_size));
        };

        if let Ok(status_interval) = env::var(ROUGHENOUGH_STATUS_INTERVAL) {
            let val: u16 = status_interval
                .parse()
                .unwrap_or_else(|_| panic!("invalid status_interval: {}", status_interval));

            cfg.status_interval = Duration::from_secs(u64::from(val));
        };

        if let Ok(kms_protection) = env::var(ROUGHENOUGH_KMS_PROTECTION) {
            cfg.kms_protection = kms_protection
                .parse()
                .unwrap_or_else(|_| panic!("invalid kms_protection value: {}", kms_protection));
        }

        if let Ok(health_check_port) = env::var(ROUGHENOUGH_HEALTH_CHECK_PORT) {
            let val: u16 = health_check_port
                .parse()
                .unwrap_or_else(|_| panic!("invalid health_check_port: {}", health_check_port));

            cfg.health_check_port = Some(val);
        };

        if let Ok(mut client_stats) = env::var(ROUGHENOUGH_CLIENT_STATS) {
            client_stats.make_ascii_lowercase();
            
            cfg.client_stats = client_stats == "yes" || client_stats == "on";
        }

        if let Ok(fault_percentage) = env::var(ROUGHENOUGH_FAULT_PERCENTAGE) {
            cfg.fault_percentage = fault_percentage
                .parse()
                .unwrap_or_else(|_| panic!("invalid fault_percentage: {}", fault_percentage));
        };

        Ok(cfg)
    }
}

impl ServerConfig for EnvironmentConfig {
    fn interface(&self) -> &str {
        self.interface.as_ref()
    }

    fn port(&self) -> u16 {
        self.port
    }

    fn seed(&self) -> Vec<u8> {
        self.seed.clone()
    }

    fn batch_size(&self) -> u8 {
        self.batch_size
    }

    fn status_interval(&self) -> Duration {
        self.status_interval
    }

    fn kms_protection(&self) -> &KmsProtection {
        &self.kms_protection
    }

    fn health_check_port(&self) -> Option<u16> {
        self.health_check_port
    }

    fn client_stats_enabled(&self) -> bool {
        self.client_stats
    }

    fn fault_percentage(&self) -> u8 {
        self.fault_percentage
    }
}