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// Copyright 2019-2024 ChainSafe Systems
// SPDX-License-Identifier: Apache-2.0, MIT

use std::str::FromStr;

/// Get the value of an environment variable, or a default value if it is not set or cannot be
/// parsed.
pub fn env_or_default<T: FromStr>(key: &str, default: T) -> T {
    std::env::var(key)
        .ok()
        .and_then(|v| v.parse().ok())
        .unwrap_or(default)
}

/// Check if the given environment variable is set to truthy value.
pub fn is_env_truthy(env: &str) -> bool {
    match std::env::var(env) {
        Ok(var) => matches!(var.to_lowercase().as_str(), "1" | "true"),
        _ => false,
    }
}

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

    #[test]
    fn test_env_or_default() {
        // variable set, should return its parsed value
        std::env::set_var("TEST_ENV", "42");
        assert_eq!(env_or_default("TEST_ENV", 0), 42);

        // variable not set, should return default
        std::env::remove_var("TEST_ENV");
        assert_eq!(env_or_default("TEST_ENV", 0), 0);

        // unparsable value given the default type, should return default
        std::env::set_var("TEST_ENV", "42");
        assert!(!env_or_default("TEST_ENV", false));
    }

    #[test]
    fn test_is_env_truthy() {
        let cases = [
            ("1", true),
            ("true", true),
            ("0", false),
            ("false", false),
            ("", false),
            ("cthulhu", false),
        ];

        for (input, expected) in cases.iter() {
            std::env::set_var("TEST_ENV", input);
            assert_eq!(is_env_truthy("TEST_ENV"), *expected);
        }
    }
}