use anyhow::{Context, Result};
use serde::Deserialize;
use std::{env, fs::File, io::BufReader};

/// Email server credentials.
#[derive(Deserialize)]
pub struct EmailServer {
    pub server_name: String,
    pub email: String,
    pub password: String,
}

/// UTC offset for time formatting.
#[derive(Deserialize)]
pub struct UtcOffset {
    pub hours: i8,
    pub minutes: i8,
}

/// Error messages for localization.
#[derive(Deserialize)]
pub struct ErrorMessages {
    pub captcha_error: String,
    pub email_error: String,
}

/// Field localization strings in a form with label and invalid feedback on wrong field input.
#[derive(Deserialize)]
pub struct Field {
    pub label: String,
    pub invalid_feedback: String,
}

/// Localization strings.
#[derive(Deserialize)]
pub struct Strings {
    pub description: String,
    pub title: String,
    pub name_field: Field,
    pub email_field: Field,
    /// No invalid feedback because it is optional.
    pub telefon_field_label: String,
    pub message_field: Field,
    pub captcha_field: Field,
    pub submit: String,
    pub success: String,
}

/// Configuration.
#[derive(Deserialize)]
pub struct Config {
    /// The language tag of the HTML file.
    pub lang: String,
    /// The path prefix of all routes.
    pub path_prefix: String,
    /// The server socket address including port.
    pub socket_address: String,
    pub email_server: EmailServer,
    /// From mailbox.
    pub email_from: String,
    /// To mailbox.
    pub email_to: String,
    pub log_file: String,
    pub utc_offset: UtcOffset,
    pub error_messages: ErrorMessages,
    pub strings: Strings,
}

impl Config {
    /// Parses the configuration from the config path in the environment variable.
    pub fn build() -> Result<Self> {
        // The environment variable with the path to the config file.
        let config_file_var = "CF_CONFIG_FILE";
        let config_path = env::var(config_file_var)
            .with_context(|| format!("Environment variable {config_file_var} missing!"))?;

        let file = File::open(&config_path)
            .with_context(|| format!("Can not open the config file at the path {config_path}"))?;
        let reader = BufReader::new(file);
        let config =
            serde_yaml::from_reader(reader).context("Can not parse the YAML config file!")?;

        Ok(config)
    }
}