use std::fmt;
use std::path::PathBuf;

use serde::{Deserialize, Serialize};

/// 密钥材料的三种来源：文件、环境变量、内联（明文 PEM 或 base64）。
#[derive(Clone, Deserialize, Serialize)]
#[serde(untagged)]
pub enum SecretMaterial {
    File { file: PathBuf },
    Env { env: String },
    Inline(String),
}

impl SecretMaterial {
    pub fn resolve(&self) -> Result<String, String> {
        match self {
            Self::File { file } => std::fs::read_to_string(file).map_err(|error| {
                format!("secret file {} is not readable: {error}", file.display())
            }),
            Self::Env { env } => std::env::var(env)
                .map_err(|_| format!("secret environment variable {env} is not set")),
            Self::Inline(text) => Ok(text.trim().to_owned()),
        }
    }

    pub fn is_empty(&self) -> bool {
        match self {
            Self::Inline(text) => text.trim().is_empty(),
            _ => false,
        }
    }
}

impl Default for SecretMaterial {
    fn default() -> Self {
        Self::Inline(String::new())
    }
}

impl fmt::Debug for SecretMaterial {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::File { file } => formatter
                .debug_struct("SecretMaterial")
                .field("file", file)
                .finish_non_exhaustive(),
            Self::Env { env } => formatter
                .debug_struct("SecretMaterial")
                .field("env", env)
                .finish_non_exhaustive(),
            Self::Inline(_) => formatter
                .debug_struct("SecretMaterial")
                .field("inline", &"<redacted>")
                .finish(),
        }
    }
}