//! Small shared helpers: clock, randomness, hashing, language maps.

use rand::RngCore;
use sha2::{Digest, Sha256};
use std::collections::BTreeMap;
use time::OffsetDateTime;
use time::format_description::well_known::Rfc3339;

/// Languages of the interface and of the editorial translations (Yvv, 2026-10-21).
pub const LANGS: [&str; 3] = ["fr", "en", "es"];

pub fn now() -> String {
    stamp(OffsetDateTime::now_utc())
}

pub fn stamp(at: OffsetDateTime) -> String {
    at.replace_nanosecond(0).unwrap_or(at).format(&Rfc3339).unwrap_or_default()
}

pub fn in_days(days: i64) -> String {
    stamp(OffsetDateTime::now_utc() + time::Duration::days(days))
}

pub fn in_seconds(secs: i64) -> String {
    stamp(OffsetDateTime::now_utc() + time::Duration::seconds(secs))
}

/// 32 random bytes, hex — session tokens, invitation tokens, OAuth state.
pub fn token() -> String {
    let mut bytes = [0u8; 32];
    rand::rng().fill_bytes(&mut bytes);
    hex::encode(bytes)
}

/// 16 random bytes, hex — row identifiers.
pub fn id() -> String {
    let mut bytes = [0u8; 16];
    rand::rng().fill_bytes(&mut bytes);
    hex::encode(bytes)
}

pub fn sha256_hex(data: &str) -> String {
    hex::encode(Sha256::digest(data.as_bytes()))
}

/// The hash a translation is pinned to: it goes stale when the source changes.
pub fn source_hash(title: &str, body: &str) -> String {
    sha256_hex(&format!("{title}\n\u{1f}\n{body}"))
}

pub type LangMap = BTreeMap<String, String>;

pub fn lang_json(map: &LangMap) -> String {
    serde_json::to_string(map).unwrap_or_else(|_| "{}".into())
}

pub fn parse_lang(raw: &str) -> LangMap {
    serde_json::from_str(raw).unwrap_or_default()
}

pub fn is_lang(lang: &str) -> bool {
    LANGS.contains(&lang)
}