//! Multi-user profiles on one device.
//!
//! A "profile" is an account on the *currently connected* Jellyfin server that
//! this device has signed into at least once. The rows have existed since the
//! first schema (`users`), and so have `storage_get_users` /
//! `storage_set_active_user`; what was missing was never the storage but the
//! decision of who may switch to what — which is domain logic, and stays here.
//!
//! Two things this module is careful about:
//!
//! - **Switching is not logging out.** `auth_logout` calls Jellyfin's logout
//!   endpoint, which invalidates the token server-side. That is precisely the
//!   behaviour a switch must not have, or every switch back would need a
//!   password. Nothing here calls it.
//! - **"Child account" is not modelled.** A child's profile is simply one with
//!   no PIN. The frontend receives an opaque [`UnlockMethod`] and renders it; it
//!   never infers a role, and no role taxonomy is invented on either side.
//!
//! TRACES: UR-082, UR-083, UR-084 | DR-267, DR-268

pub mod pin;
pub mod store;
pub mod switch;

use serde::{Deserialize, Serialize};

/// How a profile is entered.
///
/// Deliberately not "adult"/"child": the app has no way to know a person's age
/// and no business encoding one. It knows whether a code is set.
///
/// TRACES: UR-083 | DR-276
#[derive(specta::Type, Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum UnlockMethod {
    /// One tap. No code set.
    None,
    /// A numeric code gates the switch.
    Pin,
}

/// A switchable account on this device.
///
/// TRACES: UR-082 | DR-267
#[derive(specta::Type, Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Profile {
    pub user_id: String,
    pub username: String,
    pub server_id: String,
    /// Jellyfin's primary-image tag, for the tile. `None` renders initials.
    pub avatar_tag: Option<String>,
    pub unlock_method: UnlockMethod,
    pub last_used_at: Option<String>,
    pub is_active: bool,
}

/// The result of an unlock attempt.
///
/// Note the explicit field renames. tauri-specta emits tagged-union *fields*
/// with their Rust names rather than camelCasing them, so a field that would
/// differ between the two conventions is renamed here by hand — the same trap
/// that produced `new_url` on the frontend once already.
///
/// TRACES: UR-083, UR-084 | DR-268, DR-269
#[derive(specta::Type, Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "camelCase")]
pub enum UnlockOutcome {
    /// Switched. The profile is now active.
    Ok {
        #[serde(rename = "userId")]
        user_id: String,
    },
    /// Wrong code, attempts left.
    WrongPin {
        #[serde(rename = "attemptsRemaining")]
        attempts_remaining: u32,
    },
    /// Too many wrong codes; refused until this RFC3339 instant.
    LockedOut { until: String },
    /// No code is recoverable from here — sign in with the account password.
    NeedsPassword,
}

/// What the app should do when it starts.
///
/// The decision is backend state (profile count, PIN presence, a stored
/// setting), so the frontend asks rather than computes. A single account with no
/// PIN always resumes, which is what keeps this feature invisible until it is
/// wanted.
///
/// TRACES: UR-082 | DR-274
#[derive(specta::Type, Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "camelCase")]
pub enum StartupTarget {
    /// Resume this profile without asking.
    Resume {
        #[serde(rename = "userId")]
        user_id: String,
    },
    /// Show the picker.
    Picker,
}

/// Decide the startup target from the profiles present and the user's setting.
///
/// Pure, because the rule is worth testing and the inputs are trivial to state:
///
/// - No profiles at all → picker (which renders as the first-run login).
/// - The last-used profile has a PIN → picker, regardless of the setting. A code
///   that could be skipped by relaunching is not a code.
/// - More than one profile and "ask who's watching" is on → picker.
/// - Otherwise → resume, exactly as the app behaved before profiles existed.
///
/// TRACES: UR-082 | DR-274
pub fn startup_target(profiles: &[Profile], ask_on_start: bool) -> StartupTarget {
    let last_used = profiles
        .iter()
        .max_by(|a, b| a.last_used_at.cmp(&b.last_used_at));

    match last_used {
        None => StartupTarget::Picker,
        Some(p) if p.unlock_method == UnlockMethod::Pin => StartupTarget::Picker,
        Some(_) if ask_on_start && profiles.len() > 1 => StartupTarget::Picker,
        Some(p) => StartupTarget::Resume {
            user_id: p.user_id.clone(),
        },
    }
}

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

    fn profile(id: &str, unlock: UnlockMethod, last_used: Option<&str>) -> Profile {
        Profile {
            user_id: id.to_string(),
            username: id.to_string(),
            server_id: "server-1".to_string(),
            avatar_tag: None,
            unlock_method: unlock,
            last_used_at: last_used.map(|s| s.to_string()),
            is_active: false,
        }
    }

    /// UT: the pre-profiles install — one account, no PIN — never sees a picker.
    #[test]
    fn single_pinless_profile_resumes() {
        let profiles = vec![profile(
            "u1",
            UnlockMethod::None,
            Some("2026-01-01T00:00:00Z"),
        )];
        assert_eq!(
            startup_target(&profiles, true),
            StartupTarget::Resume {
                user_id: "u1".to_string()
            },
            "a lone profile resumes even with the setting on"
        );
    }

    /// UT: a PIN is not skippable by relaunching the app.
    #[test]
    fn pinned_last_profile_always_asks() {
        let profiles = vec![profile(
            "u1",
            UnlockMethod::Pin,
            Some("2026-01-01T00:00:00Z"),
        )];
        assert_eq!(startup_target(&profiles, false), StartupTarget::Picker);
    }

    /// UT: several pinless profiles resume the last one unless asked to ask.
    #[test]
    fn multiple_profiles_follow_the_setting() {
        let profiles = vec![
            profile("u1", UnlockMethod::None, Some("2026-01-01T00:00:00Z")),
            profile("u2", UnlockMethod::None, Some("2026-02-01T00:00:00Z")),
        ];
        assert_eq!(
            startup_target(&profiles, false),
            StartupTarget::Resume {
                user_id: "u2".to_string()
            },
            "resumes the most recently used"
        );
        assert_eq!(startup_target(&profiles, true), StartupTarget::Picker);
    }

    /// UT: nothing signed in yet.
    #[test]
    fn no_profiles_shows_the_picker() {
        assert_eq!(startup_target(&[], false), StartupTarget::Picker);
    }
}