/*
 * Copyright (C) 2026 Mateusz Gruszczyński @linuxiarz.pl
 * Source-Available Code / Dual-Licensed.
 *
 * Free for non-commercial and evaluation use under terms of BSL/GPLv3.
 * Commercial or production use requires a valid paid license.
 * See LICENSE file in repository root for details.
 */

use lettre::message::Mailbox;

use crate::state::{SmtpConfig, SmtpSecurity};

use super::values::ConfigValues;

pub(super) fn load_smtp(
    values: &ConfigValues,
) -> Result<Option<SmtpConfig>, Box<dyn std::error::Error>> {
    let Some(host) = values.optional("SMTP_HOST") else {
        return Ok(None);
    };

    let port = values.get("SMTP_PORT", "587").parse()?;
    let security = match values.optional("SMTP_SECURITY") {
        Some(value) => parse_smtp_security(&value)?,
        None => smtp_security_for_port(port),
    };

    Ok(Some(SmtpConfig {
        host,
        port,
        security,
        username: values.get("SMTP_USERNAME", ""),
        password: values.get("SMTP_PASSWORD", ""),
        from: normalize_smtp_from(values.required("SMTP_FROM", "SMTP_HOST is set")?)?,
        public_url: values.required("PUBLIC_URL", "SMTP_HOST is set")?,
    }))
}

fn smtp_security_for_port(port: u16) -> SmtpSecurity {
    match port {
        465 => SmtpSecurity::Tls,
        587 => SmtpSecurity::StartTls,
        _ => SmtpSecurity::None,
    }
}

fn parse_smtp_security(value: &str) -> Result<SmtpSecurity, Box<dyn std::error::Error>> {
    match value.trim().to_ascii_lowercase().as_str() {
        "none" | "plain" => Ok(SmtpSecurity::None),
        "starttls" => Ok(SmtpSecurity::StartTls),
        "tls" | "ssl" | "smtps" => Ok(SmtpSecurity::Tls),
        _ => Err("SMTP_SECURITY must be one of: none, starttls, tls".into()),
    }
}

fn normalize_smtp_from(value: String) -> Result<String, Box<dyn std::error::Error>> {
    let trimmed = value.trim();
    if trimmed.is_empty() {
        return Err("SMTP_FROM cannot be empty".into());
    }
    if trimmed.parse::<Mailbox>().is_ok() {
        return Ok(trimmed.to_owned());
    }

    let unquoted = match (trimmed.as_bytes().first(), trimmed.as_bytes().last()) {
        (Some(b'"'), Some(b'"')) | (Some(b'\''), Some(b'\'')) if trimmed.len() >= 2 => {
            trimmed[1..trimmed.len() - 1].trim()
        }
        _ => return Err(format!("SMTP_FROM is not a valid mailbox: {trimmed}").into()),
    };
    if unquoted.is_empty() {
        return Err("SMTP_FROM cannot be empty".into());
    }
    unquoted
        .parse::<Mailbox>()
        .map_err(|error| format!("SMTP_FROM is not a valid mailbox: {error}"))?;
    Ok(unquoted.to_owned())
}

#[cfg(test)]
#[path = "../tests/config_smtp.rs"]
mod tests;