//! Account settings (hub spec §6.3 `/settings/*`): profile, security,
//! linked identities, tokens.

use super::{filters, Error, Page, Shell};
use crate::auth::{self, totp, Viewer, ViewerAccount};
use crate::db::{self, accounts};
use crate::Shared;
use askama::Template;
use axum::extract::{Form, Multipart, Path, Query, State};
use axum::http::{header, HeaderMap, StatusCode};
use axum::response::{IntoResponse, Redirect, Response};
use oxy_core::identity::{Identity, Signature};
use serde::Deserialize;

/// The signed-in account, or a redirect to sign in.
pub fn require(viewer: &Viewer, shell: &Shell) -> Result<ViewerAccount, Error> {
    viewer.0.clone().ok_or_else(|| Error::redirect(format!("/login?next={}", urlencode(&shell.path))))
}

pub fn urlencode(s: &str) -> String {
    let mut out = String::new();
    for b in s.bytes() {
        match b {
            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' | b'/' => out.push(b as char),
            _ => out.push_str(&format!("%{b:02X}")),
        }
    }
    out
}

pub fn csrf(viewer: &Viewer, token: &str, shell: &Shell) -> Result<(), Error> {
    if viewer.csrf_ok(token) {
        Ok(())
    } else {
        Err(Error::bad(shell.clone(), "This form has expired; reload the page and try again."))
    }
}

#[derive(Template)]
#[template(path = "settings.html")]
pub struct SettingsPage {
    shell: Shell,
    me: accounts::Account,
    notice: Option<String>,
    error: Option<String>,
    /// The theme cookie's value, for the Appearance form.
    theme: &'static str,
    themes: &'static [(&'static str, &'static str)],
    /// The backdrop cookie's value and the choices (docs/backgrounds.md §7).
    backdrop: &'static str,
    backdrops: &'static [(&'static str, &'static str)],
    /// Whether the hub sends mail, for the "send a new link" button.
    mail: bool,
}

/// The themes (hub spec §6.1): the cookie value and its label.
const THEMES: &[(&str, &str)] = &[("light", "Light"), ("dark", "Dark"), ("auto", "Match the system")];

/// Backdrops (docs/backgrounds.md §7): the cookie value and its label.
const BACKDROPS: &[(&str, &str)] = &[("moving", "Moving"), ("still", "Still"), ("off", "Off")];

/// The backdrop the request's cookie asks for; moving when unset.
fn backdrop_of(headers: &HeaderMap) -> &'static str {
    let v = auth::viewer::cookie(headers, "backdrop").unwrap_or_default();
    BACKDROPS.iter().map(|(t, _)| *t).find(|t| *t == v).unwrap_or("moving")
}

/// The theme the request's cookie asks for; light when unset or unknown.
fn theme_of(headers: &HeaderMap) -> &'static str {
    let v = auth::viewer::cookie(headers, "theme").unwrap_or_default();
    THEMES.iter().map(|(t, _)| *t).find(|t| *t == v).unwrap_or("light")
}

impl SettingsPage {
    fn new(shell: Shell, me: accounts::Account, headers: &HeaderMap) -> SettingsPage {
        SettingsPage {
            shell,
            me,
            notice: None,
            error: None,
            theme: theme_of(headers),
            themes: THEMES,
            backdrop: backdrop_of(headers),
            backdrops: BACKDROPS,
            mail: false,
        }
    }

    fn with_mail(mut self, app: &Shared) -> Self {
        self.mail = crate::mail::enabled(app);
        self
    }

    fn notice(mut self, n: impl Into<String>) -> Self {
        self.notice = Some(n.into());
        self
    }

    fn error(mut self, e: impl Into<String>) -> Self {
        self.error = Some(e.into());
        self
    }
}

pub async fn profile(State(app): State<Shared>, viewer: Viewer, headers: HeaderMap) -> Result<Page<SettingsPage>, Error> {
    let shell = Shell::new(&app, "/settings", &viewer);
    let me = require(&viewer, &shell)?;
    Ok(Page(SettingsPage::new(shell, me.account, &headers).with_mail(&app)))
}

/// `POST /settings/avatar`: upload or remove the profile picture.
pub async fn avatar(
    State(app): State<Shared>,
    viewer: Viewer,
    headers: HeaderMap,
    multipart: Multipart,
) -> Result<Page<SettingsPage>, Error> {
    let shell = Shell::new(&app, "/settings", &viewer);
    let me = require(&viewer, &shell)?;
    let upload = super::avatar::read_upload(multipart).await;
    csrf(&viewer, &upload.csrf, &shell)?;
    let result = super::avatar::apply(&app, "account", me.account.id, upload).await;
    if result.is_ok() {
        accounts::audit(&app.db, Some(&me.account), "profile.picture", &me.account.username, "").await.ok();
    }
    let fresh = accounts::account_by_id(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?.unwrap_or(me.account);
    let page = SettingsPage::new(shell, fresh, &headers).with_mail(&app);
    Ok(Page(match result {
        Ok(m) => page.notice(m),
        Err(e) => page.error(e),
    }))
}

/// `POST /settings/email/verify`: send a new verification link.
pub async fn resend_verification(
    State(app): State<Shared>,
    viewer: Viewer,
    headers: HeaderMap,
    Form(f): Form<super::session::CsrfForm>,
) -> Result<Page<SettingsPage>, Error> {
    let shell = Shell::new(&app, "/settings", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf, &shell)?;
    let page = SettingsPage::new(shell, me.account.clone(), &headers).with_mail(&app);
    Ok(Page(match super::recovery::send_verification(&app, &me.account).await {
        Ok(()) if me.account.email_verified => page.notice("Your email is already verified."),
        Ok(()) => page.notice(format!("A verification link is on its way to {}.", me.account.email)),
        Err(e) => page.error(e),
    }))
}

#[derive(Deserialize)]
pub struct AppearanceForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    theme: String,
    #[serde(default)]
    backdrop: String,
}

/// Remember the theme and the backdrop in cookies for a year; the page
/// scripts apply them.
pub async fn appearance(State(app): State<Shared>, viewer: Viewer, Form(f): Form<AppearanceForm>) -> Result<Response, Error> {
    let shell = Shell::new(&app, "/settings", &viewer);
    require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let Some((theme, _)) = THEMES.iter().find(|(t, _)| *t == f.theme) else {
        return Err(Error::bad(shell, "Pick dark, light or match the system."));
    };
    let secure = if app.config.base_url().starts_with("https://") { "; Secure" } else { "" };
    let backdrop = if f.backdrop.is_empty() { "moving" } else { f.backdrop.as_str() };
    let Some((backdrop, _)) = BACKDROPS.iter().find(|(b, _)| *b == backdrop) else {
        return Err(Error::bad(shell, "Pick a moving, still or no background."));
    };
    Ok((
        StatusCode::SEE_OTHER,
        axum::response::AppendHeaders([
            (header::SET_COOKIE, format!("theme={theme}; Path=/; Max-Age=31536000; SameSite=Lax{secure}")),
            (header::SET_COOKIE, format!("backdrop={backdrop}; Path=/; Max-Age=31536000; SameSite=Lax{secure}")),
            (header::LOCATION, "/settings".to_string()),
        ]),
    )
        .into_response())
}

#[derive(Deserialize)]
pub struct ProfileForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    display_name: String,
    email: String,
    #[serde(default)]
    bio: String,
    #[serde(default)]
    website: String,
    #[serde(default)]
    location: String,
    #[serde(default)]
    bluesky: String,
    #[serde(default)]
    mastodon: String,
    #[serde(default)]
    github: String,
}

pub async fn update_profile(
    State(app): State<Shared>,
    viewer: Viewer,
    headers: HeaderMap,
    Form(f): Form<ProfileForm>,
) -> Result<Page<SettingsPage>, Error> {
    let shell = Shell::new(&app, "/settings", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let website = f.website.trim();
    if !(website.is_empty() || website.starts_with("https://") || website.starts_with("http://")) || website.len() > 200 {
        return Ok(Page(
            SettingsPage::new(shell, me.account, &headers).with_mail(&app).error("The website must be an http:// or https:// address."),
        ));
    }
    // Accounts elsewhere: checked and normalised, or refused by name.
    let link = |given: &str, what: &str, parse: fn(&str) -> Option<String>| -> Result<String, String> {
        if given.trim().is_empty() {
            Ok(String::new())
        } else {
            parse(given).ok_or_else(|| format!("That is not a {what}."))
        }
    };
    let links = (|| {
        Ok::<_, String>((
            link(&f.bluesky, "Bluesky handle (such as andy.bsky.social)", crate::social::bluesky)?,
            link(&f.mastodon, "Mastodon address (such as @andy@mastodon.social)", crate::social::mastodon)?,
            link(&f.github, "GitHub username", crate::social::github)?,
        ))
    })();
    let (bluesky, mastodon, github) = match links {
        Ok(l) => l,
        Err(msg) => return Ok(Page(SettingsPage::new(shell, me.account, &headers).with_mail(&app).error(&msg))),
    };
    let bio: String = f.bio.trim().chars().take(280).collect();
    let location: String = f.location.trim().chars().take(80).collect();
    accounts::set_profile(&app.db, me.account.id, f.display_name.trim(), f.email.trim())
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::set_bio(&app.db, me.account.id, &bio, website, &location).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::set_links(&app.db, me.account.id, &bluesky, &mastodon, &github).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let changed = me.account.email != f.email.trim();
    let updated =
        accounts::account_by_id(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?.unwrap_or(me.account);
    let mut notice = "Profile saved.".to_string();
    if changed && !updated.email.is_empty() {
        accounts::audit(&app.db, Some(&updated), "email.changed", &updated.username, "").await.ok();
        match super::recovery::send_verification(&app, &updated).await {
            Ok(()) => notice = format!("Profile saved. A verification link is on its way to {}.", updated.email),
            Err(e) => notice = format!("Profile saved. {e}"),
        }
    }
    Ok(Page(SettingsPage::new(shell, updated, &headers).with_mail(&app).notice(notice)))
}

#[derive(Deserialize)]
pub struct PasswordForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    current: String,
    password: String,
}

pub async fn change_password(
    State(app): State<Shared>,
    viewer: Viewer,
    headers: HeaderMap,
    Form(f): Form<PasswordForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, "/settings", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    if !auth::verify_password(&me.account.password_hash, &f.current) {
        return Ok(
            Page(SettingsPage::new(shell, me.account, &headers).with_mail(&app).error("Your current password is wrong.")).into_response()
        );
    }
    if let Err(e) = auth::password_ok(&f.password) {
        return Ok(Page(SettingsPage::new(shell, me.account, &headers).with_mail(&app).error(e)).into_response());
    }
    let hash = auth::hash_password(&f.password).map_err(|e| Error::bad(shell.clone(), e.to_string()))?;
    // A new session salt signs out every other session; this one is renewed.
    accounts::set_password(&app.db, me.account.id, &hash, &auth::random_hex(16)).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "password.changed", &me.account.username, "").await.ok();
    let fresh = accounts::account_by_id(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?.unwrap_or(me.account);
    Ok(super::session::signed_in(&app, &fresh, "/settings/security").await)
}

#[derive(Template)]
#[template(path = "settings_security.html")]
pub struct SecurityPage {
    shell: Shell,
    me: accounts::Account,
    notice: Option<String>,
    error: Option<String>,
    /// Enrolment in progress: secret, URI and QR.
    enrol: Option<(String, String, String)>,
    recovery: Vec<String>,
    /// Providers on this hub and the login connected, if any (#106).
    connected: Vec<(&'static str, &'static str, Option<String>)>,
    /// Where the account is signed in (oxygenhub#223).
    sessions: Vec<SessionView>,
}

/// One signed-in browser, as Settings › Security lists it.
pub struct SessionView {
    pub id: i64,
    pub current: bool,
    pub browser: String,
    pub address: String,
    pub seen_ms: i64,
    pub created_ms: i64,
}

/// "Firefox on Linux" from a User-Agent; "Unknown browser" when it says nothing useful.
pub fn browser_of(agent: &str) -> String {
    let has = |s: &str| agent.contains(s);
    let browser = if has("Edg/") {
        "Edge"
    } else if has("OPR/") {
        "Opera"
    } else if has("Firefox/") {
        "Firefox"
    } else if has("Chrome/") || has("Chromium/") {
        "Chrome"
    } else if has("Safari/") {
        "Safari"
    } else if has("curl/") {
        "curl"
    } else {
        ""
    };
    let os = if has("Android") {
        "Android"
    } else if has("iPhone") || has("iPad") {
        "iOS"
    } else if has("Windows") {
        "Windows"
    } else if has("Mac OS X") || has("Macintosh") {
        "macOS"
    } else if has("CrOS") {
        "ChromeOS"
    } else if has("Linux") {
        "Linux"
    } else {
        ""
    };
    match (browser, os) {
        ("", "") => "Unknown browser".into(),
        (b, "") => b.into(),
        ("", o) => format!("A browser on {o}"),
        (b, o) => format!("{b} on {o}"),
    }
}

async fn sessions_of(app: &Shared, me: &crate::auth::ViewerAccount) -> sqlx::Result<Vec<SessionView>> {
    Ok(crate::db::sessions::of_account(&app.db, me.account.id, &me.account.session_salt)
        .await?
        .into_iter()
        .map(|s| SessionView {
            id: s.id,
            current: s.id == me.session_id,
            browser: browser_of(&s.agent),
            address: s.address,
            seen_ms: s.seen_ms,
            created_ms: s.created_ms,
        })
        .collect())
}

#[derive(Deserialize)]
pub struct SecurityQuery {
    notice: Option<String>,
    error: Option<String>,
}

pub async fn security(State(app): State<Shared>, viewer: Viewer, Query(q): Query<SecurityQuery>) -> Result<Page<SecurityPage>, Error> {
    let shell = Shell::new(&app, "/settings/security", &viewer);
    let me = require(&viewer, &shell)?;
    let connected = connected_of(&app, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let sessions = sessions_of(&app, &me).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    Ok(Page(SecurityPage { shell, me: me.account, notice: q.notice, error: q.error, enrol: None, recovery: vec![], connected, sessions }))
}

/// Each sign-in provider this hub offers, with the login connected to the account.
pub async fn connected_of(app: &Shared, account_id: i64) -> sqlx::Result<Vec<(&'static str, &'static str, Option<String>)>> {
    let links = crate::signin::links_of(&app.db, account_id).await?;
    let mut out = vec![];
    for p in crate::signin::enabled(app).await {
        out.push((p.id, p.name, links.iter().find(|l| l.provider == p.id).map(|l| l.login.clone())));
    }
    Ok(out)
}

#[derive(Deserialize)]
pub struct TotpForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    #[serde(default)]
    secret: String,
    #[serde(default)]
    code: String,
    #[serde(default)]
    password: String,
}

/// Step one: show a fresh secret to scan.
pub async fn totp_begin(State(app): State<Shared>, viewer: Viewer, Form(f): Form<TotpForm>) -> Result<Page<SecurityPage>, Error> {
    let shell = Shell::new(&app, "/settings/security", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let secret = totp::new_secret();
    let uri = totp::uri(&app.config.site.name, &me.account.username, &secret);
    let qr = totp::qr_svg(&uri).unwrap_or_default();
    Ok(Page(SecurityPage {
        shell,
        me: me.account,
        notice: None,
        error: None,
        enrol: Some((secret, uri, qr)),
        recovery: vec![],
        connected: vec![],
        sessions: vec![],
    }))
}

/// Step two: the first code proves the app holds the secret.
pub async fn totp_enable(State(app): State<Shared>, viewer: Viewer, Form(f): Form<TotpForm>) -> Result<Page<SecurityPage>, Error> {
    let shell = Shell::new(&app, "/settings/security", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let now = (db::now_ms() / 1000) as u64;
    if f.secret.is_empty() || !totp::verify(&f.secret, &f.code, now) {
        let uri = totp::uri(&app.config.site.name, &me.account.username, &f.secret);
        let qr = totp::qr_svg(&uri).unwrap_or_default();
        return Ok(Page(SecurityPage {
            shell,
            me: me.account,
            notice: None,
            error: Some("That code did not match; scan again and enter the current code.".into()),
            enrol: Some((f.secret, uri, qr)),
            recovery: vec![],
            connected: vec![],
            sessions: vec![],
        }));
    }
    let (codes, stored) = totp::new_recovery_codes();
    accounts::set_totp(&app.db, me.account.id, Some(&f.secret), &stored).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "totp.enabled", &me.account.username, "").await.ok();
    let fresh = accounts::account_by_id(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?.unwrap_or(me.account);
    Ok(Page(SecurityPage {
        shell,
        me: fresh,
        notice: Some("Two-factor authentication is on. Keep these recovery codes somewhere safe; each works once.".into()),
        error: None,
        enrol: None,
        recovery: codes,
        connected: vec![],
        sessions: vec![],
    }))
}

pub async fn totp_disable(State(app): State<Shared>, viewer: Viewer, Form(f): Form<TotpForm>) -> Result<Page<SecurityPage>, Error> {
    let shell = Shell::new(&app, "/settings/security", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    if !auth::verify_password(&me.account.password_hash, &f.password) {
        return Ok(Page(SecurityPage {
            shell,
            me: me.account,
            notice: None,
            error: Some("Your password is wrong.".into()),
            enrol: None,
            recovery: vec![],
            connected: vec![],
            sessions: vec![],
        }));
    }
    accounts::set_totp(&app.db, me.account.id, None, "").await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "totp.disabled", &me.account.username, "").await.ok();
    let fresh = accounts::account_by_id(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?.unwrap_or(me.account);
    Ok(Page(SecurityPage {
        shell,
        me: fresh,
        notice: Some("Two-factor authentication is off.".into()),
        error: None,
        enrol: None,
        recovery: vec![],
        connected: vec![],
        sessions: vec![],
    }))
}

/// Sign out everywhere: a new session salt invalidates every cookie, then
/// this browser gets a fresh one.
pub async fn sessions_reset(State(app): State<Shared>, viewer: Viewer, Form(f): Form<super::session::CsrfForm>) -> Result<Response, Error> {
    let shell = Shell::new(&app, "/settings/security", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf, &shell)?;
    accounts::set_session_salt(&app.db, me.account.id, &auth::random_hex(16)).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "sessions.reset", &me.account.username, "").await.ok();
    let fresh = accounts::account_by_id(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?.unwrap_or(me.account);
    Ok(super::session::signed_in(&app, &fresh, "/settings/security").await)
}

/// `POST /settings/security/sessions/{id}/end`: sign one browser out.
pub async fn session_end(
    State(app): State<Shared>,
    viewer: Viewer,
    Path(id): Path<i64>,
    Form(f): Form<super::session::CsrfForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, "/settings/security", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf, &shell)?;
    let ended = crate::db::sessions::end(&app.db, me.account.id, id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    if ended {
        accounts::audit(&app.db, Some(&me.account), "session.ended", &me.account.username, &id.to_string()).await.ok();
    }
    let to = if id == me.session_id { "/" } else { "/settings/security?notice=That+browser+is+signed+out." };
    Ok(Redirect::to(to).into_response())
}

// ------------------------------------------------------------------- keys

#[derive(Template)]
#[template(path = "settings_keys.html")]
pub struct KeysPage {
    shell: Shell,
    me: accounts::Account,
    keys: Vec<accounts::LinkedIdentity>,
    notice: Option<String>,
    error: Option<String>,
    /// A pending challenge: id, hex bytes, identity name.
    pending: Option<(i64, String, String)>,
}

async fn keys_page(
    app: &Shared,
    shell: Shell,
    me: accounts::Account,
    notice: Option<String>,
    error: Option<String>,
    pending: Option<(i64, String, String)>,
) -> Result<Page<KeysPage>, Error> {
    let keys = accounts::identities_of(&app.db, me.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    Ok(Page(KeysPage { shell, me, keys, notice, error, pending }))
}

pub async fn keys(State(app): State<Shared>, viewer: Viewer) -> Result<Page<KeysPage>, Error> {
    let shell = Shell::new(&app, "/settings/keys", &viewer);
    let me = require(&viewer, &shell)?;
    keys_page(&app, shell, me.account, None, None, None).await
}

/// Upload an identity object (`oxy identity export`): the hub issues a
/// challenge to sign with that key.
pub async fn keys_upload(State(app): State<Shared>, viewer: Viewer, mut multipart: Multipart) -> Result<Page<KeysPage>, Error> {
    let shell = Shell::new(&app, "/settings/keys", &viewer);
    let me = require(&viewer, &shell)?;
    let mut token = String::new();
    let mut object: Vec<u8> = Vec::new();
    while let Ok(Some(field)) = multipart.next_field().await {
        match field.name() {
            Some("_csrf") => token = field.text().await.unwrap_or_default(),
            Some("identity") => object = field.bytes().await.map(|b| b.to_vec()).unwrap_or_default(),
            _ => {}
        }
    }
    csrf(&viewer, &token, &shell)?;
    let identity = match Identity::decode(&object) {
        Ok(i) => i,
        Err(e) => return keys_page(&app, shell, me.account, None, Some(format!("That is not an identity file: {e}")), None).await,
    };
    if identity.hash() == app.hub_key.key {
        let msg = "That is this hub's own key, which only the hub holds. Upload your identity: after `oxy identity delegate add` with the hub's key, run `oxy identity export` in that checkout and upload the file it writes.";
        return keys_page(&app, shell, me.account, None, Some(msg.into()), None).await;
    }
    let key = identity.hash().to_hex();
    if let Some(existing) = accounts::identity_by_key(&app.db, &key).await.map_err(|e| Error::from_db(shell.clone(), e))? {
        let msg = if existing.account_id == me.account.id {
            "That key is already linked to you. If you have delegated since (`oxy identity delegate add`), export again: a delegation makes a new version of your identity."
        } else {
            "That key is linked to another account."
        };
        return keys_page(&app, shell, me.account, None, Some(msg.into()), None).await;
    }
    let bytes = auth::random_hex(32);
    let id = accounts::create_challenge(&app.db, me.account.id, &bytes).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    sqlx::query("UPDATE challenges SET object = $1 WHERE id = $2")
        .bind(&object)
        .bind(id)
        .execute(&app.db)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?;
    keys_page(&app, shell, me.account, None, None, Some((id, bytes, identity.name))).await
}

#[derive(Deserialize)]
pub struct KeyVerifyForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    challenge: i64,
    signature: String,
}

pub async fn keys_verify(State(app): State<Shared>, viewer: Viewer, Form(f): Form<KeyVerifyForm>) -> Result<Page<KeysPage>, Error> {
    let shell = Shell::new(&app, "/settings/keys", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let object: Option<Vec<u8>> = sqlx::query_scalar("SELECT object FROM challenges WHERE id = $1 AND account_id = $2")
        .bind(f.challenge)
        .bind(me.account.id)
        .fetch_optional(&app.db)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?;
    let bytes = accounts::take_challenge(&app.db, me.account.id, f.challenge).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let (Some(object), Some(bytes)) = (object, bytes) else {
        return keys_page(&app, shell, me.account, None, Some("That challenge has expired; upload the identity again.".into()), None).await;
    };
    let Ok(identity) = Identity::decode(&object) else {
        return keys_page(&app, shell, me.account, None, Some("The stored identity is unreadable.".into()), None).await;
    };
    let sig_bytes = hex::decode(f.signature.trim()).unwrap_or_default();
    let sigs = Signature::decode_list(&sig_bytes).unwrap_or_default();
    let challenge = hex::decode(&bytes).unwrap_or_default();
    let ok = sigs.first().is_some_and(|sig| oxy_core::identity::verify_challenge(&identity, sig, &challenge).is_ok());
    if !ok {
        // Signed by another key than the one uploaded: say which, as it is
        // usually the wrong checkout or an `author.signer` set there.
        let msg = match sigs.first() {
            Some(sig) if sig.key != identity.hash() => format!(
                "That signature is by key {}, but the identity uploaded is {} ({}). Sign in a checkout whose `oxy identity export` gives that identity, without an `author.signer` set, or upload the identity that checkout exports.",
                sig.key.short(12),
                identity.hash().short(12),
                identity.name
            ),
            _ => "The signature does not verify against that identity and challenge.".into(),
        };
        return keys_page(&app, shell, me.account, None, Some(msg), None).await;
    }
    let key = identity.hash().to_hex();
    accounts::link_identity(&app.db, me.account.id, &key, &identity.name, &identity.email, &object)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "identity.linked", &key, &identity.name).await.ok();
    keys_page(&app, shell, me.account, Some("Key linked. Changes signed with it are now yours on every page.".into()), None, None).await
}

#[derive(Deserialize)]
pub struct KeyForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    key: String,
}

pub async fn keys_unlink(State(app): State<Shared>, viewer: Viewer, Form(f): Form<KeyForm>) -> Result<Page<KeysPage>, Error> {
    let shell = Shell::new(&app, "/settings/keys", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    accounts::unlink_identity(&app.db, me.account.id, &f.key).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "identity.unlinked", &f.key, "").await.ok();
    keys_page(&app, shell, me.account, Some("Key unlinked.".into()), None, None).await
}

// ----------------------------------------------------------------- tokens

#[derive(Template)]
#[template(path = "settings_tokens.html")]
pub struct TokensPage {
    shell: Shell,
    scopes: &'static [(&'static str, &'static str)],
    me: accounts::Account,
    tokens: Vec<accounts::Token>,
    /// A freshly created token, shown once.
    fresh: Option<String>,
    notice: Option<String>,
    error: Option<String>,
}

async fn tokens_page(
    app: &Shared,
    shell: Shell,
    me: accounts::Account,
    fresh: Option<String>,
    notice: Option<String>,
    error: Option<String>,
) -> Result<Page<TokensPage>, Error> {
    let tokens = accounts::tokens_of(&app.db, me.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    Ok(Page(TokensPage { shell, scopes: SCOPES, me, tokens, fresh, notice, error }))
}

pub async fn tokens(State(app): State<Shared>, viewer: Viewer) -> Result<Page<TokensPage>, Error> {
    let shell = Shell::new(&app, "/settings/tokens", &viewer);
    let me = require(&viewer, &shell)?;
    tokens_page(&app, shell, me.account, None, None, None).await
}

#[derive(Deserialize)]
pub struct TokenForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    name: String,
    #[serde(default)]
    scopes: Vec<String>,
    #[serde(default)]
    repos: String,
    #[serde(default)]
    expires_days: String,
    /// An agent uses it: tell me what it does (oxygenhub#183).
    #[serde(default)]
    agent: String,
}

/// Every scope the hub checks, with what it grants. The tokens page lists
/// exactly these, so a scope cannot exist without a checkbox.
pub const SCOPES: &[(&str, &str)] = &[
    ("repo:read", "read repositories you can see: clone, fetch, pull, and the read API"),
    ("repo:write", "push to repositories you can write to; also covers proposals, issues and checks"),
    ("repo:admin", "create repositories and change settings through the API"),
    ("proposals:write", "open, comment on and review proposals, without push access"),
    ("issues:write", "open, comment on and close issues, without push access"),
    ("checks:write", "report checks on states, for CI systems, without push access"),
    ("hooks:admin", "manage webhooks through the API"),
    ("user:read", "read your own profile through the API"),
];

pub async fn tokens_create(
    State(app): State<Shared>,
    viewer: Viewer,
    axum_extra::extract::Form(f): axum_extra::extract::Form<TokenForm>,
) -> Result<Page<TokensPage>, Error> {
    let shell = Shell::new(&app, "/settings/tokens", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let name = f.name.trim();
    if name.is_empty() {
        return tokens_page(&app, shell, me.account, None, None, Some("Give the token a name.".into())).await;
    }
    let scopes: Vec<&str> = f.scopes.iter().map(String::as_str).filter(|s| SCOPES.iter().any(|(k, _)| k == s)).collect();
    if scopes.is_empty() {
        return tokens_page(&app, shell, me.account, None, None, Some("Pick at least one scope.".into())).await;
    }
    let expires_ms = f.expires_days.trim().parse::<i64>().ok().filter(|d| *d > 0).map(|d| db::now_ms() + d * 86_400_000);
    let repos = f.repos.split(',').map(str::trim).filter(|r| !r.is_empty()).collect::<Vec<_>>().join(",");
    let (secret, hash) = auth::new_token();
    accounts::create_token(&app.db, me.account.id, name, &hash, &scopes.join(","), &repos, expires_ms)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?;
    if !f.agent.is_empty() {
        if let Ok(Some(t)) = accounts::token_by_hash(&app.db, &hash).await {
            accounts::set_token_agent(&app.db, me.account.id, t.id, true).await.map_err(|e| Error::from_db(shell.clone(), e))?;
        }
    }
    accounts::audit(&app.db, Some(&me.account), "token.created", name, &scopes.join(",")).await.ok();
    tokens_page(&app, shell, me.account, Some(secret), Some("Copy the token now; it is not shown again.".into()), None).await
}

/// Mark a token as an agent's, or not (oxygenhub#183): what is done with
/// an agent's token is told to its owner, as anyone else's doing is.
pub async fn tokens_agent(
    State(app): State<Shared>,
    viewer: Viewer,
    Path(id): Path<i64>,
    Form(f): Form<super::session::CsrfForm>,
) -> Result<Page<TokensPage>, Error> {
    let shell = Shell::new(&app, "/settings/tokens", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf, &shell)?;
    let tokens = accounts::tokens_of(&app.db, me.account.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let Some(t) = tokens.iter().find(|t| t.id == id) else {
        return tokens_page(&app, shell, me.account, None, None, Some("No such token.".into())).await;
    };
    accounts::set_token_agent(&app.db, me.account.id, id, !t.agent).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "token.agent", &t.name, if t.agent { "off" } else { "on" }).await.ok();
    let notice = if t.agent {
        format!("{} is no longer marked as an agent's.", t.name)
    } else {
        format!("{} is an agent's: you will hear what it does.", t.name)
    };
    tokens_page(&app, shell, me.account, None, Some(notice), None).await
}

pub async fn tokens_delete(
    State(app): State<Shared>,
    viewer: Viewer,
    Path(id): Path<i64>,
    Form(f): Form<super::session::CsrfForm>,
) -> Result<Page<TokensPage>, Error> {
    let shell = Shell::new(&app, "/settings/tokens", &viewer);
    let me = require(&viewer, &shell)?;
    csrf(&viewer, &f.csrf, &shell)?;
    accounts::delete_token(&app.db, me.account.id, id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    accounts::audit(&app.db, Some(&me.account), "token.deleted", &id.to_string(), "").await.ok();
    tokens_page(&app, shell, me.account, None, Some("Token deleted.".into()), None).await
}

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

    #[test]
    fn browsers_are_named_from_their_agent() {
        let ff = "Mozilla/5.0 (X11; Linux x86_64; rv:131.0) Gecko/20100101 Firefox/131.0";
        let chrome_mac =
            "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0 Safari/537.36";
        let edge = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0 Safari/537.36 Edg/129.0";
        let iphone = "Mozilla/5.0 (iPhone; CPU iPhone OS 17_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.6 Mobile/15E148 Safari/604.1";
        assert_eq!(browser_of(ff), "Firefox on Linux");
        assert_eq!(browser_of(chrome_mac), "Chrome on macOS");
        assert_eq!(browser_of(edge), "Edge on Windows");
        assert_eq!(browser_of(iphone), "Safari on iOS");
        assert_eq!(browser_of(""), "Unknown browser");
    }
}