//! Profile commands: who can use this device, and how they get in.
//!
//! The rule that shapes this whole module: **switching is not logging out**.
//! [`auth_logout`](super::auth::auth_logout) calls Jellyfin's logout endpoint,
//! which invalidates the token server-side — so a switch built on it would make
//! every switch back cost a password, which is the problem this feature exists
//! to solve. Nothing here calls it.
//!
//! TRACES: UR-082, UR-083, UR-084 | DR-267, DR-268, DR-269, DR-270, DR-274

use std::sync::Arc;

use log::{info, warn};
use tauri::{Emitter, State};

use crate::commands::sessions::SessionPollerWrapper;
use crate::commands::storage::{CredentialStoreWrapper, DatabaseWrapper};
use crate::profiles::pin::{self, PinDecision, PinState};
use crate::profiles::switch::{plan, SwitchStep};
use crate::profiles::{startup_target, store, Profile, StartupTarget, UnlockOutcome};
use crate::storage::db_service::{DatabaseService, Query, QueryParam, RusqliteService};

/// Settings key for "ask who's watching on start".
const ASK_ON_START_KEY: &str = "profiles_ask_on_start";

fn service(db: &State<'_, DatabaseWrapper>) -> Result<Arc<RusqliteService>, String> {
    let database = db.0.lock().map_err(|e| e.to_string())?;
    Ok(Arc::new(database.service()))
}

/// The server this device is signed in to, as `(server_id, server_url)`.
///
/// Every profile operation is scoped to it — this is where the same-server
/// constraint is actually enforced, rather than by omitting a URL field from a
/// form.
///
/// The fallback to the `servers` table is not a convenience. When the last-used
/// profile has a PIN, `auth_initialize` deliberately does **not** restore its
/// session, so at startup there is no in-memory session to read — and the picker
/// still has to know which server's profiles to list. Reading it from storage is
/// what lets the PIN gate a real thing rather than just a screen.
async fn current_server(
    db: &Arc<RusqliteService>,
    auth_manager: &State<'_, super::auth::AuthManagerWrapper>,
) -> Result<(String, String), String> {
    if let Some(session) = auth_manager.0.get_session().await {
        return Ok((session.server_id, session.server_url));
    }

    db.query_optional(
        Query::new("SELECT id, url FROM servers ORDER BY last_connected_at DESC LIMIT 1"),
        |row| Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?)),
    )
    .await
    .map_err(|e| e.to_string())?
    .ok_or_else(|| "No server connected".to_string())
}

async fn ask_on_start(db: &Arc<RusqliteService>) -> bool {
    let query = Query::with_params(
        "SELECT value FROM app_settings WHERE key = ?",
        vec![QueryParam::String(ASK_ON_START_KEY.to_string())],
    );
    db.query_optional(query, |row| row.get::<_, String>(0))
        .await
        .ok()
        .flatten()
        .map(|v| v == "1" || v.eq_ignore_ascii_case("true"))
        .unwrap_or(false)
}

/// List the accounts this device knows for the current server.
///
/// TRACES: UR-082 | DR-267
#[tauri::command]
#[specta::specta]
pub async fn profiles_list(
    db: State<'_, DatabaseWrapper>,
    auth_manager: State<'_, super::auth::AuthManagerWrapper>,
) -> Result<Vec<Profile>, String> {
    let svc = service(&db)?;
    let (server_id, _) = current_server(&svc, &auth_manager).await?;
    store::list_profiles(&svc, &server_id).await
}

/// Whether startup should resume an account or ask who is watching.
///
/// The decision is backend state, so the frontend asks rather than computes it.
///
/// TRACES: UR-082 | DR-274
#[tauri::command]
#[specta::specta]
pub async fn profiles_startup_target(
    db: State<'_, DatabaseWrapper>,
    auth_manager: State<'_, super::auth::AuthManagerWrapper>,
) -> Result<StartupTarget, String> {
    let svc = service(&db)?;
    let (server_id, _) = match current_server(&svc, &auth_manager).await {
        Ok(pair) => pair,
        // Nothing signed in yet: the picker doubles as first-run login.
        Err(_) => return Ok(StartupTarget::Picker),
    };
    let profiles = store::list_profiles(&svc, &server_id).await?;
    Ok(startup_target(&profiles, ask_on_start(&svc).await))
}

/// Read the "ask who's watching on start" setting.
///
/// Separate from [`profiles_startup_target`] on purpose: the target can be
/// `Picker` for reasons that have nothing to do with this setting — a
/// PIN-protected last profile always asks — so deriving the toggle's position
/// from it would show the user a switch that does not describe what it controls.
///
/// TRACES: UR-082 | DR-274
#[tauri::command]
#[specta::specta]
pub async fn profiles_get_ask_on_start(db: State<'_, DatabaseWrapper>) -> Result<bool, String> {
    let svc = service(&db)?;
    Ok(ask_on_start(&svc).await)
}

/// Turn "ask who's watching on start" on or off.
///
/// TRACES: UR-082 | DR-274
#[tauri::command]
#[specta::specta]
pub async fn profiles_set_ask_on_start(
    db: State<'_, DatabaseWrapper>,
    enabled: bool,
) -> Result<(), String> {
    let svc = service(&db)?;
    let query = Query::with_params(
        "INSERT INTO app_settings (key, value, updated_at) VALUES (?, ?, CURRENT_TIMESTAMP)
         ON CONFLICT(key) DO UPDATE SET value = excluded.value, updated_at = CURRENT_TIMESTAMP",
        vec![
            QueryParam::String(ASK_ON_START_KEY.to_string()),
            QueryParam::String(if enabled { "1" } else { "0" }.to_string()),
        ],
    );
    svc.execute(query).await.map_err(|e| e.to_string())?;
    Ok(())
}

/// Enter a profile, with its PIN if it has one.
///
/// A profile with no PIN ignores whatever `pin` was passed — the frontend cannot
/// invent a lock the backend does not have, and cannot skip one it does.
///
/// TRACES: UR-082, UR-083 | DR-267, DR-268, DR-270
#[tauri::command]
#[specta::specta]
#[allow(clippy::too_many_arguments)]
pub async fn profiles_unlock(
    app: tauri::AppHandle,
    db: State<'_, DatabaseWrapper>,
    creds: State<'_, CredentialStoreWrapper>,
    auth_manager: State<'_, super::auth::AuthManagerWrapper>,
    repository_manager: State<'_, super::repository::RepositoryManagerWrapper>,
    session_poller: State<'_, SessionPollerWrapper>,
    user_id: String,
    pin_code: Option<String>,
) -> Result<UnlockOutcome, String> {
    let svc = service(&db)?;

    let profile = store::get_profile(&svc, &user_id)
        .await?
        .ok_or_else(|| format!("Unknown profile: {}", user_id))?;

    // Same-server constraint, checked at the point of use rather than trusted
    // from the caller.
    let (server_id, _) = current_server(&svc, &auth_manager).await?;
    if profile.server_id != server_id {
        return Err("Profile belongs to a different server".to_string());
    }

    if let Some((hash, state)) = store::get_pin(&svc, &user_id).await? {
        let candidate = pin_code.unwrap_or_default();
        let matches = pin::verify_pin(&candidate, &hash);
        let (decision, next_state) = pin::evaluate(&state, chrono::Utc::now(), matches);
        store::save_pin_state(&svc, &user_id, &next_state).await?;

        match decision {
            PinDecision::Reject { attempts_remaining } => {
                return Ok(UnlockOutcome::WrongPin { attempts_remaining })
            }
            PinDecision::Locked { until } => {
                return Ok(UnlockOutcome::LockedOut {
                    until: until.to_rfc3339(),
                })
            }
            PinDecision::Accept => {}
        }
    }

    let outgoing = active_user_id(&svc).await;
    execute_switch(
        &app,
        &svc,
        &repository_manager,
        &session_poller,
        outgoing.as_deref(),
        &user_id,
    )
    .await?;
    adopt_session(db, creds, &auth_manager).await?;

    Ok(UnlockOutcome::Ok { user_id })
}

/// Enter a profile with its Jellyfin password, for someone who has forgotten
/// their PIN.
///
/// There is deliberately no reset token and no recovery secret: the account's
/// own password is already the authority over it, and a second credential
/// guarding the same thing would only be a weaker one. A successful password
/// entry also clears the lockout, which is what makes a forgotten PIN a
/// detour rather than a dead end.
///
/// TRACES: UR-084 | DR-269
#[tauri::command]
#[specta::specta]
#[allow(clippy::too_many_arguments)]
pub async fn profiles_unlock_with_password(
    app: tauri::AppHandle,
    db: State<'_, DatabaseWrapper>,
    creds: State<'_, CredentialStoreWrapper>,
    auth_manager: State<'_, super::auth::AuthManagerWrapper>,
    repository_manager: State<'_, super::repository::RepositoryManagerWrapper>,
    session_poller: State<'_, SessionPollerWrapper>,
    user_id: String,
    password: String,
    device_id: String,
) -> Result<UnlockOutcome, String> {
    let svc = service(&db)?;
    let profile = store::get_profile(&svc, &user_id)
        .await?
        .ok_or_else(|| format!("Unknown profile: {}", user_id))?;

    let (server_id, server_url) = current_server(&svc, &auth_manager).await?;
    if profile.server_id != server_id {
        return Err("Profile belongs to a different server".to_string());
    }

    let result = auth_manager
        .0
        .login(&server_url, &profile.username, &password, &device_id)
        .await?;

    if result.user.id != user_id {
        return Err("Signed in as a different account".to_string());
    }

    save_token(&creds, &user_id, &result.access_token)?;

    // The password got in, so the PIN counters have served their purpose.
    store::save_pin_state(&svc, &user_id, &PinState::fresh()).await?;

    let outgoing = active_user_id(&svc).await;
    execute_switch(
        &app,
        &svc,
        &repository_manager,
        &session_poller,
        outgoing.as_deref(),
        &user_id,
    )
    .await?;
    adopt_session(db, creds, &auth_manager).await?;

    Ok(UnlockOutcome::Ok { user_id })
}

/// Add another account from the **current** server to this device.
///
/// Takes no server URL. That is the same-server constraint expressed as a
/// signature rather than as form validation: there is no way to ask this command
/// for an account somewhere else.
///
/// TRACES: UR-082 | DR-267
#[tauri::command]
#[specta::specta]
pub async fn profiles_add(
    db: State<'_, DatabaseWrapper>,
    creds: State<'_, CredentialStoreWrapper>,
    auth_manager: State<'_, super::auth::AuthManagerWrapper>,
    username: String,
    password: String,
    pin_code: Option<String>,
    device_id: String,
) -> Result<Profile, String> {
    if let Some(code) = &pin_code {
        pin::validate_pin(code)?;
    }

    let svc = service(&db)?;
    let (server_id, server_url) = current_server(&svc, &auth_manager).await?;

    let result = auth_manager
        .0
        .login(&server_url, &username, &password, &device_id)
        .await?;

    let insert = Query::with_params(
        "INSERT INTO users (id, server_id, username, last_login_at)
         VALUES (?, ?, ?, CURRENT_TIMESTAMP)
         ON CONFLICT(id) DO UPDATE SET
            server_id = excluded.server_id,
            username = excluded.username,
            last_login_at = CURRENT_TIMESTAMP",
        vec![
            QueryParam::String(result.user.id.clone()),
            QueryParam::String(server_id.clone()),
            QueryParam::String(result.user.name.clone()),
        ],
    );
    svc.execute(insert).await.map_err(|e| e.to_string())?;

    save_token(&creds, &result.user.id, &result.access_token)?;

    if let Some(code) = pin_code {
        let hash = pin::hash_pin(&code)?;
        store::set_pin(&svc, &result.user.id, &hash).await?;
    }

    info!("[Profiles] Added profile {}", result.user.name);

    store::get_profile(&svc, &result.user.id)
        .await?
        .ok_or_else(|| "Profile vanished after being added".to_string())
}

/// Set, change, or clear a profile's PIN.
///
/// Changing an existing PIN requires the current one. Clearing it (`new_pin =
/// None`) does too — otherwise the lock could be removed by whoever is standing
/// in front of the unlocked device, which is exactly who it exists to stop.
///
/// TRACES: UR-083 | DR-268
#[tauri::command]
#[specta::specta]
pub async fn profiles_set_pin(
    db: State<'_, DatabaseWrapper>,
    user_id: String,
    current_pin: Option<String>,
    new_pin: Option<String>,
) -> Result<(), String> {
    let svc = service(&db)?;

    if let Some((hash, _)) = store::get_pin(&svc, &user_id).await? {
        let provided = current_pin.unwrap_or_default();
        if !pin::verify_pin(&provided, &hash) {
            return Err("Current PIN is incorrect".to_string());
        }
    }

    match new_pin {
        Some(code) => {
            pin::validate_pin(&code)?;
            let hash = pin::hash_pin(&code)?;
            store::set_pin(&svc, &user_id, &hash).await
        }
        None => store::clear_pin(&svc, &user_id).await,
    }
}

/// Forget a profile on this device.
///
/// Does not call Jellyfin's logout endpoint: removing an account from the family
/// TV should not sign that person out on their phone. The stored token is
/// deleted locally, which is the part that actually belongs to this device.
///
/// TRACES: UR-082 | DR-267
#[tauri::command]
#[specta::specta]
pub async fn profiles_remove(
    db: State<'_, DatabaseWrapper>,
    creds: State<'_, CredentialStoreWrapper>,
    user_id: String,
) -> Result<(), String> {
    let svc = service(&db)?;

    if active_user_id(&svc).await.as_deref() == Some(user_id.as_str()) {
        return Err("Switch to another profile before removing this one".to_string());
    }

    {
        let store = creds.0.lock().map_err(|e| e.to_string())?;
        if let Err(e) = store.delete_token(&user_id) {
            warn!("[Profiles] Could not delete stored token: {}", e);
        }
    }

    store::remove_profile(&svc, &user_id).await
}

// --- internals ---------------------------------------------------------------

fn save_token(
    creds: &State<'_, CredentialStoreWrapper>,
    user_id: &str,
    token: &str,
) -> Result<(), String> {
    let store = creds.0.lock().map_err(|e| e.to_string())?;
    store
        .save_token(user_id, token)
        .map(|_| ())
        .map_err(|e| e.to_string())
}

async fn active_user_id(db: &Arc<RusqliteService>) -> Option<String> {
    db.query_optional(
        Query::new("SELECT id FROM users WHERE is_active = 1 LIMIT 1"),
        |row| row.get::<_, String>(0),
    )
    .await
    .ok()
    .flatten()
}

/// Run a switch plan.
///
/// The ordering comes from [`crate::profiles::switch::plan`] rather than being
/// written out here, because the ordering is the invariant worth testing and an
/// end-to-end switch needs two real accounts on a real server to exercise.
///
/// One step is deliberately not executed here: `BuildRepository`. Repository
/// handles are created by the frontend (`repository_create`) because building
/// one needs the token and URL it already assembles at login, so the
/// `profile-switched` event is the signal to do it. What stays in Rust is the
/// part that matters — that the old handle is destroyed *before* the active user
/// flips, so nothing can write under the wrong id in between.
///
/// TRACES: UR-082 | DR-270
async fn execute_switch(
    app: &tauri::AppHandle,
    db: &Arc<RusqliteService>,
    repository_manager: &State<'_, super::repository::RepositoryManagerWrapper>,
    session_poller: &State<'_, SessionPollerWrapper>,
    from: Option<&str>,
    to: &str,
) -> Result<(), String> {
    let online = true;
    let steps = plan(from, to, online);

    for step in steps {
        match step {
            SwitchStep::StopPlayback => {
                // The queue cannot outlive its owner: a report landing after the
                // flip would attribute one account's viewing to another.
                if let Err(e) = app.emit("profile-switch-stop-playback", ()) {
                    warn!("[Profiles] Could not signal playback stop: {}", e);
                }
            }
            SwitchStep::ParkSyncQueue { user_id } => {
                // Rows stay queued under their own user id; nothing is dropped.
                // Parking is simply declining to drain them under a different
                // token, which the drain already keys on.
                info!("[Profiles] Parking sync queue for {}", user_id);
            }
            SwitchStep::StopSessionPoller => session_poller.0.stop(),
            SwitchStep::ClearLockscreenMetadata => {
                if let Err(e) = app.emit("profile-switch-clear-metadata", ()) {
                    warn!("[Profiles] Could not clear lockscreen metadata: {}", e);
                }
            }
            SwitchStep::DestroyRepository => {
                let manager = &repository_manager.0;
                for handle in manager.handles() {
                    manager.destroy(&handle);
                }
            }
            SwitchStep::SetActiveUser { user_id } => {
                set_active_user(db, &user_id).await?;
            }
            SwitchStep::BuildRepository { .. } => {
                // Owned by the frontend; see the doc comment above.
            }
            SwitchStep::StartSessionPoller => {
                // The poller restarts with the new session once the frontend has
                // built its repository, for the same reason.
            }
            SwitchStep::RefreshVisibility { user_id } => {
                info!("[Profiles] Visibility refresh queued for {}", user_id);
            }
            SwitchStep::EmitSwitched { user_id } => {
                app.emit("profile-switched", serde_json::json!({ "userId": user_id }))
                    .map_err(|e| e.to_string())?;
            }
        }
    }

    Ok(())
}

/// Make the newly-active profile the session the rest of the backend acts as.
///
/// The token lives in the credential store, which the frontend cannot read, so
/// the swap has to happen here — the frontend then rebuilds its repository
/// handle from the session it can now read back. This mirrors what
/// [`auth_initialize`](super::auth::auth_initialize) does on a cold start, and
/// deliberately reuses the same storage path rather than a second one that could
/// drift from it.
///
/// TRACES: UR-082 | DR-270
async fn adopt_session(
    db: State<'_, DatabaseWrapper>,
    creds: State<'_, CredentialStoreWrapper>,
    auth_manager: &State<'_, super::auth::AuthManagerWrapper>,
) -> Result<(), String> {
    let active = super::storage::storage_get_active_session(db, creds)
        .await?
        .ok_or_else(|| "Profile has no stored session".to_string())?;

    let normalized_url = crate::auth::AuthManager::normalize_url(&active.server_url)?;

    auth_manager
        .0
        .set_session(Some(crate::auth::Session {
            user_id: active.user_id,
            username: active.username,
            server_id: active.server_id,
            server_url: normalized_url,
            server_name: active.server_name,
            access_token: active.access_token,
            verified: false,
            needs_reauth: false,
        }))
        .await;

    Ok(())
}

async fn set_active_user(db: &Arc<RusqliteService>, user_id: &str) -> Result<(), String> {
    db.execute(Query::new("UPDATE users SET is_active = 0"))
        .await
        .map_err(|e| e.to_string())?;
    db.execute(Query::with_params(
        "UPDATE users SET is_active = 1, last_login_at = CURRENT_TIMESTAMP WHERE id = ?",
        vec![QueryParam::String(user_id.to_string())],
    ))
    .await
    .map_err(|e| e.to_string())?;
    Ok(())
}