//! Interfaces for writing and reading PeachCloud configurations, stored in yaml.
//!
//! Different PeachCloud microservices import peach-lib, so that they can share
//! this interface.
//!
//! Config values are looked up from three locations in this order by key name:
//! 1. from environmental variables
//! 2. from a configuration file
//! 3. from default values
//!
//! The configuration file is located at: "/var/lib/peachcloud/config.yml"
//! unless its path is configured by setting PEACH_CONFIG_PATH env variable.

use std::collections::{BTreeMap, HashMap};
use std::{env, fs};

use fslock::LockFile;
use lazy_static::lazy_static;
use log::debug;

use crate::error::PeachError;

// load path to main configuration file
// from PEACH_CONFIG_PATH if that environment variable is set
// or using the default value if not set
pub const DEFAULT_YAML_PATH: &str = "/var/lib/peachcloud/config.yml";
lazy_static! {
    static ref CONFIG_PATH: String = {
        if let Ok(val) = env::var("PEACH_CONFIG_PATH") {
             val
        }
        else {
            DEFAULT_YAML_PATH.to_string()
        }
    };
    // lock file (used to avoid race conditions during config reading & writing)
    // the lock file path is the config file path + ".lock"
    static ref LOCK_FILE_PATH: String = format!("{}.lock", *CONFIG_PATH);
}

// Default values for PeachCloud configs which are used for any key which is not set
// via an environment variable or in a saved configuration file.
pub fn get_peach_config_defaults() -> HashMap<String, String> {
    let peach_config_defaults: HashMap<&str, &str> = HashMap::from([
        ("STANDALONE_MODE", "true"),
        ("DISABLE_AUTH", "false"),
        ("ADDR", "127.0.0.1"),
        ("PORT", "8000"),
        ("EXTERNAL_DOMAIN", ""),
        ("DYN_DOMAIN", ""),
        (
            "DYN_DNS_SERVER_ADDRESS",
            "http://dynserver.dyn.peachcloud.org",
        ),
        ("DYN_USE_CUSTOM_SERVER", "true"),
        ("DYN_TSIG_KEY_PATH", ""),
        ("DYN_NAMESERVER", "ns.peachcloud.org"),
        ("DYN_ENABLED", "false"),
        ("SSB_ADMIN_IDS", ""),
        ("ADMIN_PASSWORD_HASH", "47"),
        ("TEMPORARY_PASSWORD_HASH", ""),
        ("GO_SBOT_DATADIR", "/home/peach/.ssb-go"),
        ("PEACH_CONFIGDIR", "/var/lib/peachcloud"),
        ("PEACH_HOMEDIR", "/home/peach"),
        ("PEACH_WEBDIR", "/usr/share/peach-web"),
    ]);
    // convert HashMap<&str, &str> to HashMap<String, String> and return
    let pc_defaults: HashMap<String, String> = peach_config_defaults
        .iter()
        .map(|(key, val)| (key.to_string(), val.to_string()))
        .collect();
    pc_defaults
}

// primary interface for getting config values
// Config values are looked up from three locations in this order by key name:
// 1. from environmental variables
// 2. from a configuration file
// 3. from default values
pub fn get_config_value(key: &str) -> Result<String, PeachError> {
    // first check if there is an environmental variable set
    if let Ok(val) = env::var(key) {
        Ok(val)
    } else {
        // then check if a value is set in the config file
        let peach_config_on_disc = load_peach_config_from_disc()?;
        let val = peach_config_on_disc.get(key);
        // if no value is found in the config file, then get the default value
        match val {
            // return config value
            Some(v) => Ok(v.to_string()),
            // get default value
            None => {
                match get_peach_config_defaults().get(key) {
                    Some(v) => Ok(v.to_string()),
                    // if this key was not found in the defaults, then it was an invalid key
                    None => Err(PeachError::InvalidKey {
                        key: key.to_string(),
                    }),
                }
            }
        }
    }
}

// helper function to load PeachCloud configuration file saved to disc
pub fn load_peach_config_from_disc() -> Result<HashMap<String, String>, PeachError> {
    let peach_config_exists = std::path::Path::new(CONFIG_PATH.as_str()).exists();
    // if config file does not exist, return an emtpy HashMap
    if !peach_config_exists {
        let peach_config: HashMap<String, String> = HashMap::new();
        Ok(peach_config)
    }
    // otherwise we load peach config from disk
    else {
        debug!("Loading peach config: {} exists", CONFIG_PATH.as_str());
        let contents =
            fs::read_to_string(CONFIG_PATH.as_str()).map_err(|source| PeachError::Read {
                source,
                path: CONFIG_PATH.to_string(),
            })?;
        let peach_config: HashMap<String, String> = serde_yaml::from_str(&contents)?;
        Ok(peach_config)
    }
}

// helper function to save PeachCloud configuration file to disc
// takes in a Hashmap<String, String> and saves the whole HashMap as a yaml file
// with the keys in alphabetical order
pub fn save_peach_config_to_disc(
    peach_config: HashMap<String, String>,
) -> Result<HashMap<String, String>, PeachError> {
    // use a file lock to avoid race conditions while saving config
    let mut lock = LockFile::open(&*LOCK_FILE_PATH)?;
    lock.lock()?;

    // first convert Hashmap to BTreeMap (so that keys are saved in deterministic alphabetical order)
    let ordered: BTreeMap<_, _> = peach_config.iter().collect();
    // then serialize BTreeMap as yaml
    let yaml_str = serde_yaml::to_string(&ordered)?;

    // write yaml to file
    fs::write(CONFIG_PATH.as_str(), yaml_str).map_err(|source| PeachError::Write {
        source,
        path: CONFIG_PATH.to_string(),
    })?;

    // unlock file lock
    lock.unlock()?;

    // return modified HashMap
    Ok(peach_config)
}

// helper functions for serializing and deserializing PeachConfig values from disc
pub fn save_config_value(key: &str, value: &str) -> Result<HashMap<String, String>, PeachError> {
    // get current config from disc
    let mut peach_config = load_peach_config_from_disc()?;

    // insert new key/value
    peach_config.insert(key.to_string(), value.to_string());

    // save the modified hashmap to disc
    save_peach_config_to_disc(peach_config)
}

// set all dyn configuration values at once
pub fn set_peach_dyndns_config(
    dyn_domain: &str,
    dyn_dns_server_address: &str,
    dyn_tsig_key_path: &str,
    dyn_enabled: bool,
) -> Result<HashMap<String, String>, PeachError> {
    let mut peach_config = load_peach_config_from_disc()?;
    let dyn_enabled_str = match dyn_enabled {
        true => "true",
        false => "false",
    };
    peach_config.insert("DYN_DOMAIN".to_string(), dyn_domain.to_string());
    peach_config.insert(
        "DYN_DNS_SERVER_ADDRESS".to_string(),
        dyn_dns_server_address.to_string(),
    );
    peach_config.insert(
        "DYN_TSIG_KEY_PATH".to_string(),
        dyn_tsig_key_path.to_string(),
    );
    peach_config.insert("DYN_ENABLED".to_string(), dyn_enabled_str.to_string());
    save_peach_config_to_disc(peach_config)
}

pub fn set_external_domain(
    new_external_domain: &str,
) -> Result<HashMap<String, String>, PeachError> {
    save_config_value("EXTERNAL_DOMAIN", new_external_domain)
}

pub fn get_peachcloud_domain() -> Result<Option<String>, PeachError> {
    let external_domain = get_config_value("EXTERNAL_DOMAIN")?;
    let dyn_domain = get_config_value("DYN_DOMAIN")?;
    if !external_domain.is_empty() {
        Ok(Some(external_domain))
    } else if !dyn_domain.is_empty() {
        Ok(Some(dyn_domain))
    } else {
        Ok(None)
    }
}

pub fn get_dyndns_server_address() -> Result<String, PeachError> {
    get_config_value("DYN_DNS_SERVER_ADDRESS")
}

pub fn set_dyndns_enabled_value(
    enabled_value: bool,
) -> Result<HashMap<String, String>, PeachError> {
    match enabled_value {
        true => save_config_value("DYN_ENABLED", "true"),
        false => save_config_value("DYN_ENABLED", "false"),
    }
}

pub fn get_dyndns_enabled_value() -> Result<bool, PeachError> {
    let val = get_config_value("DYN_ENABLED")?;
    Ok(val == "true")
}

pub fn set_admin_password_hash(
    password_hash: String,
) -> Result<HashMap<String, String>, PeachError> {
    save_config_value("ADMIN_PASSWORD_HASH", &password_hash)
}

pub fn get_admin_password_hash() -> Result<String, PeachError> {
    let admin_password_hash = get_config_value("ADMIN_PASSWORD_HASH")?;
    if !admin_password_hash.is_empty() {
        Ok(admin_password_hash)
    } else {
        Err(PeachError::PasswordNotSet)
    }
}

pub fn set_temporary_password_hash(
    password_hash: String,
) -> Result<HashMap<String, String>, PeachError> {
    save_config_value("TEMPORARY_PASSWORD_HASH", &password_hash)
}

pub fn get_temporary_password_hash() -> Result<String, PeachError> {
    let admin_password_hash = get_config_value("TEMPORARY_PASSWORD_HASH")?;
    if !admin_password_hash.is_empty() {
        Ok(admin_password_hash)
    } else {
        Err(PeachError::PasswordNotSet)
    }
}

// add ssb_id to vector of admin ids and save new value for SSB_ADMIN_IDS
pub fn add_ssb_admin_id(ssb_id: &str) -> Result<Vec<String>, PeachError> {
    let mut ssb_admin_ids = get_ssb_admin_ids()?;
    ssb_admin_ids.push(ssb_id.to_string());
    save_ssb_admin_ids(ssb_admin_ids)
}

// remove ssb_id from vector of admin ids if found and save new value for SSB_ADMIN_IDS
// if value is not found then return an error
pub fn delete_ssb_admin_id(ssb_id: &str) -> Result<Vec<String>, PeachError> {
    let mut ssb_admin_ids = get_ssb_admin_ids()?;
    let index_result = ssb_admin_ids.iter().position(|x| *x == ssb_id);
    match index_result {
        Some(index) => {
            ssb_admin_ids.remove(index);
            save_ssb_admin_ids(ssb_admin_ids)
        }
        None => Err(PeachError::SsbAdminIdNotFound {
            id: ssb_id.to_string(),
        }),
    }
}

// looks up the String value for SSB_ADMIN_IDS and converts it into a Vec<String>
pub fn get_ssb_admin_ids() -> Result<Vec<String>, PeachError> {
    let ssb_admin_ids_str = get_config_value("SSB_ADMIN_IDS")?;
    let ssb_admin_ids: Vec<String> = serde_json::from_str(&ssb_admin_ids_str)?;
    Ok(ssb_admin_ids)
}

// takes in a Vec<String> and saves SSB_ADMIN_IDS as a json string representation of this vec
pub fn save_ssb_admin_ids(ssb_admin_ids: Vec<String>) -> Result<Vec<String>, PeachError> {
    let ssb_admin_ids_as_json_str = serde_json::to_string(&ssb_admin_ids)?;
    save_config_value("SSB_ADMIN_IDS", &ssb_admin_ids_as_json_str)?;
    Ok(ssb_admin_ids)
}