// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
//
// SPDX-License-Identifier: GPL-2.0-or-later

//! Shared configuration validation helpers used by both `trx-server` and
//! `trx-client`.
//!
//! # Non-shared structs
//!
//! `GeneralConfig` is defined separately in each binary because the fields
//! differ:
//!
//! - **Server** `GeneralConfig`: `callsign`, `log_level`, `latitude`,
//!   `longitude`
//! - **Client** `GeneralConfig`: `callsign`, `log_level`, `website_url`,
//!   `website_name`, `ais_vessel_url_base`
//!
//! Only `callsign` and `log_level` overlap.  Merging into a single struct
//! would either bloat both binaries with unused fields or require a trait
//! abstraction that adds complexity without clear benefit.

use std::net::IpAddr;

/// A socket a component intends to bind, and what it is for.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct BoundSocket {
    pub addr: IpAddr,
    pub port: u16,
    /// Human-readable owner, e.g. `[listen]` or `[frontends.http]`.
    pub label: String,
}

impl BoundSocket {
    pub fn new(addr: IpAddr, port: u16, label: impl Into<String>) -> Self {
        Self {
            addr,
            port,
            label: label.into(),
        }
    }
}

/// Reject two components trying to bind the same socket.
///
/// A wildcard address (`0.0.0.0` / `::`) conflicts with any other address on
/// the same port, since binding it claims every interface.  Port 0 means "pick
/// an ephemeral port" and never conflicts.
pub fn check_socket_conflicts(sockets: &[BoundSocket]) -> Result<(), String> {
    for (i, a) in sockets.iter().enumerate() {
        if a.port == 0 {
            continue;
        }
        for b in &sockets[i + 1..] {
            if b.port != a.port {
                continue;
            }
            if a.addr == b.addr || a.addr.is_unspecified() || b.addr.is_unspecified() {
                return Err(format!(
                    "{} and {} would both bind {}:{}",
                    a.label, b.label, a.addr, a.port
                ));
            }
        }
    }
    Ok(())
}

/// Validate that a log level string is one of the accepted values.
///
/// Returns `Ok(())` when `level` is `None` (defaulting is handled elsewhere)
/// or a recognised level name.
pub fn validate_log_level(level: Option<&str>) -> Result<(), String> {
    if let Some(level) = level {
        match level {
            "trace" | "debug" | "info" | "warn" | "error" => {}
            _ => {
                return Err(format!(
                    "[general].log_level '{}' is invalid (expected one of: trace, debug, info, warn, error)",
                    level
                ))
            }
        }
    }
    Ok(())
}

/// Validate that a list of authentication tokens contains no empty entries.
///
/// `path` is a human-readable config path prefix used in the error message
/// (e.g. `"[listen.auth].tokens"`).
pub fn validate_tokens(path: &str, tokens: &[String]) -> Result<(), String> {
    if tokens.iter().any(|t| t.trim().is_empty()) {
        return Err(format!("{path} must not contain empty tokens"));
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    fn sock(addr: &str, port: u16, label: &str) -> BoundSocket {
        BoundSocket::new(addr.parse().unwrap(), port, label)
    }

    #[test]
    fn test_socket_conflicts_detects_exact_duplicate() {
        let err = check_socket_conflicts(&[
            sock("127.0.0.1", 8080, "[frontends.http]"),
            sock("127.0.0.1", 8080, "[frontends.http_json]"),
        ])
        .unwrap_err();
        assert!(err.contains("127.0.0.1:8080"), "unexpected error: {err}");
    }

    #[test]
    fn test_socket_conflicts_detects_wildcard_overlap() {
        assert!(check_socket_conflicts(&[
            sock("0.0.0.0", 4530, "[listen]"),
            sock("127.0.0.1", 4530, "[audio]"),
        ])
        .is_err());
    }

    #[test]
    fn test_socket_conflicts_allows_distinct_addresses() {
        assert!(check_socket_conflicts(&[
            sock("127.0.0.1", 4530, "[listen]"),
            sock("192.168.1.5", 4530, "[audio]"),
        ])
        .is_ok());
    }

    #[test]
    fn test_socket_conflicts_ignores_ephemeral_ports() {
        assert!(check_socket_conflicts(&[
            sock("127.0.0.1", 0, "[frontends.http_json]"),
            sock("127.0.0.1", 0, "[frontends.http]"),
        ])
        .is_ok());
    }

    #[test]
    fn test_validate_log_level_none() {
        assert!(validate_log_level(None).is_ok());
    }

    #[test]
    fn test_validate_log_level_valid() {
        for level in &["trace", "debug", "info", "warn", "error"] {
            assert!(validate_log_level(Some(level)).is_ok());
        }
    }

    #[test]
    fn test_validate_log_level_invalid() {
        assert!(validate_log_level(Some("verbose")).is_err());
    }

    #[test]
    fn test_validate_tokens_empty_list() {
        assert!(validate_tokens("[auth].tokens", &[]).is_ok());
    }

    #[test]
    fn test_validate_tokens_valid() {
        let tokens = vec!["abc".to_string(), "def".to_string()];
        assert!(validate_tokens("[auth].tokens", &tokens).is_ok());
    }

    #[test]
    fn test_validate_tokens_rejects_empty() {
        let tokens = vec!["abc".to_string(), "".to_string()];
        assert!(validate_tokens("[auth].tokens", &tokens).is_err());
    }

    #[test]
    fn test_validate_tokens_rejects_whitespace_only() {
        let tokens = vec!["  ".to_string()];
        assert!(validate_tokens("[auth].tokens", &tokens).is_err());
    }
}