use std::io::IsTerminal;
use std::str::FromStr;

/// Output format for all commands.
#[derive(Debug, Clone, Default, PartialEq)]
pub enum OutputMode {
    /// Human-readable text (default when stdout is a TTY)
    #[default]
    Text,
    /// Pretty-printed JSON
    Json,
    /// Single-line JSON (default when stdout is NOT a TTY, e.g. piped to jq)
    JsonCompact,
    /// KEY=VALUE pairs suitable for `source` or `.env` files
    Env,
}

impl FromStr for OutputMode {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "text" => Ok(Self::Text),
            "json" => Ok(Self::Json),
            "json-compact" => Ok(Self::JsonCompact),
            "env" => Ok(Self::Env),
            other => Err(anyhow::anyhow!(
                "Unknown output format '{}'. Valid: text, json, json-compact, env",
                other
            )),
        }
    }
}

/// Resolve the effective output mode.
/// - Explicit value from `--output` takes priority.
/// - TTY → text; non-TTY (piped/redirected) → json-compact.
pub fn resolve_output_mode(explicit: Option<&str>) -> anyhow::Result<OutputMode> {
    if let Some(s) = explicit {
        return s.parse();
    }
    if std::io::stdout().is_terminal() {
        Ok(OutputMode::Text)
    } else {
        Ok(OutputMode::JsonCompact)
    }
}