//! Full-flow integration suite against a `wiremock` fake AS (todo 21).
//!
//! The fake AS implements the d-OAuth shape: RFC 8414 discovery (PAR +
//! introspection + revocation endpoints, DPoP ES256, no userinfo), `/par`,
//! `/token`, `/introspect`, `/revoke`. Every test drives the real router with
//! `tower::ServiceExt::oneshot`: no ports are bound, no external servers
//! start, no real network is touched.

use axum::body::Body;
use axum::http::{Request, StatusCode};
use secrecy::{ExposeSecret as _, SecretString};
use server::app::build_app;
use server::config::ServerConfig;
use server::session::SESSION_COOKIE;
use server::state::AppState;
use tower::ServiceExt as _;
use wiremock::{
  Mock, MockServer, ResponseTemplate,
  matchers::{method, path},
};

type TestResult = Result<(), Box<dyn std::error::Error>>;

struct Fixture {
  app: axum::Router,
  state: AppState,
  issuer: String,
  public_jwk: serde_json::Value,
  jkt: String,
}

fn empty_lookup(_: &str) -> Option<String> {
  None
}

/// Build an app whose profile points at the fake AS, with an in-memory DPoP
/// key. The key's public JWK + thumbprint are kept for proof verification.
fn fixture_app(fake: &MockServer) -> (Fixture, tempfile::TempDir) {
  let dir = tempfile::tempdir().expect("temp dir is creatable");
  let dist = dir.path().join("dist");
  std::fs::create_dir_all(&dist).expect("fixture dist is creatable");
  std::fs::write(
    dist.join("index.html"),
    "<html><body>spa-shell</body></html>",
  )
  .expect("fixture index is writable");

  let issuer = fake.uri();
  let config_json = format!(
    r#"{{
      "server": {{ "dist_dir": {} }},
      "oauth": {{
        "issuer": "{issuer}",
        "redirect_uri": "http://127.0.0.1:3000/callback",
        "scope": "demo.read"
      }}
    }}"#,
    serde_json::to_string(&dist).expect("path serializes")
  );
  std::fs::write(dir.path().join("config.json"), config_json).expect("config is writable");
  std::fs::write(
    dir.path().join("client.json"),
    r#"{"client_id": "demo-client", "client_secret": "demo-secret"}"#,
  )
  .expect("client fixture is writable");

  let config = ServerConfig::load_from_paths_with(
    Some(&dir.path().join("config.json")),
    Some(&dir.path().join("client.json")),
    &empty_lookup,
  )
  .expect("fixture config loads");
  let key = oauth_core::dpop::key::DpopKey::generate().expect("dpop key generates");
  let public_jwk = key.public_jwk();
  let jkt = key.thumbprint().expect("thumbprint computes");
  let state = AppState::with_client(config, reqwest::Client::new()).with_dpop_key(key);
  let app = build_app(state.clone());
  (
    Fixture {
      app,
      state,
      issuer,
      public_jwk,
      jkt,
    },
    dir,
  )
}

/// d-OAuth-shaped discovery: PAR + introspection + revocation + DPoP ES256,
/// no userinfo endpoint.
async fn mount_discovery(fake: &MockServer, issuer: &str) {
  let doc = serde_json::json!({
    "issuer": issuer,
    "authorization_endpoint": format!("{issuer}/authorize"),
    "token_endpoint": format!("{issuer}/token"),
    "pushed_authorization_request_endpoint": format!("{issuer}/par"),
    "introspection_endpoint": format!("{issuer}/introspect"),
    "revocation_endpoint": format!("{issuer}/revoke"),
    "dpop_signing_alg_values_supported": ["ES256"],
  });
  Mock::given(method("GET"))
    .and(path("/.well-known/oauth-authorization-server"))
    .respond_with(ResponseTemplate::new(200).set_body_json(&doc))
    .mount(fake)
    .await;
}

async fn mount_par(fake: &MockServer) {
  Mock::given(method("POST"))
    .and(path("/par"))
    .respond_with(ResponseTemplate::new(201).set_body_json(serde_json::json!({
      "request_uri": "urn:ietf:params:oauth:request_uri:par-handle-1",
      "expires_in": 90
    })))
    .mount(fake)
    .await;
}

fn token_ok(access: &str, refresh: &str) -> ResponseTemplate {
  ResponseTemplate::new(200).set_body_json(serde_json::json!({
    "access_token": access,
    "token_type": "DPoP",
    "expires_in": 3600,
    "refresh_token": refresh,
    "scope": "demo.read",
  }))
}

async fn mount_token(fake: &MockServer, template: ResponseTemplate) {
  Mock::given(method("POST"))
    .and(path("/token"))
    .respond_with(template)
    .mount(fake)
    .await;
}

async fn mount_introspect(fake: &MockServer, body: serde_json::Value) {
  Mock::given(method("POST"))
    .and(path("/introspect"))
    .respond_with(ResponseTemplate::new(200).set_body_json(&body))
    .mount(fake)
    .await;
}

async fn mount_revoke(fake: &MockServer) {
  Mock::given(method("POST"))
    .and(path("/revoke"))
    .respond_with(ResponseTemplate::new(200))
    .mount(fake)
    .await;
}

fn active_introspection(exp: i64, iat: i64, jkt: &str) -> serde_json::Value {
  serde_json::json!({
    "active": true,
    "scope": "demo.read",
    "client_id": "demo-client",
    "token_type": "Bearer",
    "exp": exp,
    "iat": iat,
    "sub": "demo@example.com",
    "cnf": { "jkt": jkt },
  })
}

fn now_secs() -> i64 {
  std::time::SystemTime::now()
    .duration_since(std::time::UNIX_EPOCH)
    .expect("clock available")
    .as_secs() as i64
}

async fn send(
  app: axum::Router,
  request: Request<Body>,
) -> Result<axum::http::Response<Body>, Box<dyn std::error::Error>> {
  Ok(app.oneshot(request).await?)
}

fn get_request(uri: &str, cookie: Option<&str>) -> Request<Body> {
  let mut builder = Request::builder().uri(uri);
  if let Some(cookie) = cookie {
    builder = builder.header("cookie", cookie);
  }
  builder.body(Body::empty()).expect("request builds")
}

fn post_request(uri: &str, cookie: &str, csrf: &str, origin: Option<&str>) -> Request<Body> {
  let mut builder = Request::builder()
    .uri(uri)
    .method("POST")
    .header("cookie", cookie)
    .header("x-csrf-token", csrf);
  if let Some(origin) = origin {
    builder = builder.header("origin", origin);
  }
  builder.body(Body::empty()).expect("request builds")
}

async fn body_text(
  response: axum::http::Response<Body>,
) -> Result<String, Box<dyn std::error::Error>> {
  let bytes = axum::body::to_bytes(response.into_body(), usize::MAX).await?;
  Ok(std::str::from_utf8(&bytes)?.to_owned())
}

fn header_value(response: &axum::http::Response<Body>, name: &str) -> String {
  response
    .headers()
    .get(name)
    .and_then(|value| value.to_str().ok())
    .unwrap_or_default()
    .to_owned()
}

fn sid_from_set_cookie(set_cookie: &str) -> Option<String> {
  set_cookie.split(';').next().and_then(|pair| {
    let (name, value) = pair.split_once('=')?;
    (name.trim() == SESSION_COOKIE).then(|| value.trim().to_owned())
  })
}

fn cookie_for(sid: &str) -> String {
  format!("{SESSION_COOKIE}={sid}")
}

/// `/oauth/start` -> bound `(state, sid)`.
async fn start_flow(fixture: &Fixture) -> Result<(String, String), Box<dyn std::error::Error>> {
  let response = send(fixture.app.clone(), get_request("/oauth/start", None)).await?;
  assert_eq!(response.status(), StatusCode::FOUND);
  let location = header_value(&response, "location");
  assert!(
    location.contains("/authorize"),
    "unexpected Location: {location}"
  );
  assert!(
    location.contains("request_uri"),
    "PAR handle missing: {location}"
  );
  let sid = sid_from_set_cookie(&header_value(&response, "set-cookie")).expect("sid cookie");
  let state = fixture
    .state
    .pending()
    .pending_state_for_session(&sid)
    .expect("state bound to the session");
  Ok((state, sid))
}

/// `/callback` happy path -> rotated sid.
async fn callback_flow(
  fixture: &Fixture,
  state: &str,
  sid: &str,
) -> Result<String, Box<dyn std::error::Error>> {
  let response = send(
    fixture.app.clone(),
    get_request(
      &format!("/callback?code=authcode-1&state={state}"),
      Some(&cookie_for(sid)),
    ),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::FOUND);
  assert_eq!(header_value(&response, "location"), "/dashboard");
  let next = sid_from_set_cookie(&header_value(&response, "set-cookie")).expect("rotated cookie");
  assert_ne!(sid, next, "session id must rotate on login");
  Ok(next)
}

async fn session_json(
  fixture: &Fixture,
  sid: &str,
) -> Result<(StatusCode, serde_json::Value), Box<dyn std::error::Error>> {
  let response = send(
    fixture.app.clone(),
    get_request("/api/session", Some(&cookie_for(sid))),
  )
  .await?;
  let status = response.status();
  let body = body_text(response).await?;
  let json: serde_json::Value =
    serde_json::from_str(&body).expect("session body is JSON on every status");
  Ok((status, json))
}

// ---- happy path: the whole flow end to end ----

#[tokio::test]
async fn full_flow_start_to_logout() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  mount_token(&fake, token_ok("access-1", "refresh-1")).await;
  let now = now_secs();
  mount_introspect(
    &fake,
    active_introspection(now + 300, now - 10, &fixture.jkt),
  )
  .await;
  mount_revoke(&fake).await;

  // `/oauth/start` -> extract `state`.
  let (state, sid) = start_flow(&fixture).await?;

  // `/callback` -> session + rotation.
  let sid = callback_flow(&fixture, &state, &sid).await?;

  // `/api/session` -> subject + scopes + DPoP display type.
  let (status, json) = session_json(&fixture, &sid).await?;
  assert_eq!(status, StatusCode::OK);
  assert_eq!(json["subject"], "demo@example.com");
  assert_eq!(json["scope"], serde_json::json!(["demo.read"]));
  assert_eq!(json["token_type"], "DPoP");
  assert_eq!(
    json["cnf"]["jkt"],
    serde_json::Value::String(fixture.jkt.clone())
  );
  let csrf = json["csrf_token"]
    .as_str()
    .expect("csrf_token served")
    .to_owned();

  // `/api/refresh` -> rotation receipt, no tokens in the body.
  let response = send(
    fixture.app.clone(),
    post_request("/api/refresh", &cookie_for(&sid), &csrf, None),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::OK);
  let body = body_text(response).await?;
  assert!(
    body.contains("refreshed"),
    "unexpected refresh body: {body}"
  );
  for forbidden in ["access-1", "refresh-1", "demo-secret"] {
    assert!(
      !body.contains(forbidden),
      "secret leaked into refresh: {body}"
    );
  }

  // `/api/logout` -> cleared session + AS note.
  let response = send(
    fixture.app.clone(),
    post_request("/api/logout", &cookie_for(&sid), &csrf, None),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::OK);
  let body = body_text(response).await?;
  assert!(
    body.contains("provider logout endpoint"),
    "logout note missing: {body}"
  );
  assert!(
    fixture.state.sessions().get(&sid).is_none(),
    "logout clears the session"
  );

  // Post-logout session probe is 401.
  let (status, _) = session_json(&fixture, &sid).await?;
  assert_eq!(status, StatusCode::UNAUTHORIZED);

  // Both tokens were revoked best-effort.
  let sent = fake.received_requests().await.unwrap_or_default();
  assert_eq!(
    sent
      .iter()
      .filter(|request| request.url.path() == "/revoke")
      .count(),
    2,
    "refresh + access must both be revoked"
  );
  Ok(())
}

// ---- DPoP proofs verify against the JWK the client sent ----

#[tokio::test]
async fn dpop_proofs_verify_against_the_sent_jwk() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  mount_token(&fake, token_ok("access-1", "refresh-1")).await;
  let now = now_secs();
  mount_introspect(
    &fake,
    active_introspection(now + 300, now - 10, &fixture.jkt),
  )
  .await;

  let (state, sid) = start_flow(&fixture).await?;
  let sid = callback_flow(&fixture, &state, &sid).await?;
  let (_, json) = session_json(&fixture, &sid).await?;
  let csrf = json["csrf_token"]
    .as_str()
    .expect("csrf_token served")
    .to_owned();

  // Refresh so the fake AS sees two proofs (exchange + rotation).
  let response = send(
    fixture.app.clone(),
    post_request("/api/refresh", &cookie_for(&sid), &csrf, None),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::OK);

  let sent = fake.received_requests().await.unwrap_or_default();
  let proofs: Vec<String> = sent
    .iter()
    .filter(|request| request.url.path() == "/token")
    .filter_map(|request| {
      request
        .headers
        .get("dpop")
        .and_then(|value| value.to_str().ok())
        .map(str::to_owned)
    })
    .collect();
  assert_eq!(proofs.len(), 2, "exchange + refresh each send a proof");

  let mut jtis = Vec::new();
  for proof in &proofs {
    let verified = oauth_core::dpop::proof::verify_proof(proof).expect("proof verifies");
    assert_eq!(verified.htm, "POST");
    assert_eq!(verified.htu, format!("{}/token", fixture.issuer));
    let sent_jwk = verified.header.get("jwk").expect("proof carries its JWK");
    assert_eq!(sent_jwk, &fixture.public_jwk, "proof key is the client key");
    let jkt = oauth_core::dpop::key::thumbprint_of(sent_jwk).expect("thumbprint computes");
    assert_eq!(
      jkt, fixture.jkt,
      "bound key matches the introspected cnf.jkt"
    );
    jtis.push(verified.jti.clone());
  }
  assert_ne!(jtis[0], jtis[1], "each proof carries a fresh jti");
  Ok(())
}

// ---- failure paths ----

#[tokio::test]
async fn state_mismatch_never_exchanges() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  mount_token(&fake, token_ok("access-1", "refresh-1")).await;

  let (_state, sid) = start_flow(&fixture).await?;
  let response = send(
    fixture.app.clone(),
    get_request(
      "/callback?code=authcode-1&state=forged-state",
      Some(&cookie_for(&sid)),
    ),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::BAD_REQUEST);
  let sent = fake.received_requests().await.unwrap_or_default();
  assert!(
    sent.iter().all(|request| request.url.path() != "/token"),
    "state mismatch must never trigger an exchange"
  );
  Ok(())
}

#[tokio::test]
async fn discovery_503_yields_a_typed_error_page() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  Mock::given(method("GET"))
    .and(path("/.well-known/oauth-authorization-server"))
    .respond_with(ResponseTemplate::new(503))
    .mount(&fake)
    .await;
  Mock::given(method("GET"))
    .and(path("/.well-known/openid-configuration"))
    .respond_with(ResponseTemplate::new(503))
    .mount(&fake)
    .await;

  let response = send(fixture.app.clone(), get_request("/oauth/start", None)).await?;
  assert_eq!(response.status(), StatusCode::BAD_GATEWAY);
  let body = body_text(response).await?;
  assert!(
    body.contains("unavailable"),
    "expected a typed error page, got: {body}"
  );
  for forbidden in ["demo-secret", "code_verifier", "verifier"] {
    assert!(
      !body.contains(forbidden),
      "secret leaked into error page: {body}"
    );
  }
  Ok(())
}

#[tokio::test]
async fn invalid_client_exchange_fails_closed_without_session() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  mount_token(
    &fake,
    ResponseTemplate::new(401).set_body_json(serde_json::json!({
      "error": "invalid_client",
      "error_description": "unknown client",
    })),
  )
  .await;

  let (state, sid) = start_flow(&fixture).await?;
  let response = send(
    fixture.app.clone(),
    get_request(
      &format!("/callback?code=authcode-1&state={state}"),
      Some(&cookie_for(&sid)),
    ),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::BAD_GATEWAY);
  let body = body_text(response).await?;
  assert!(
    !body.contains("demo-secret"),
    "secret leaked into error page: {body}"
  );
  let (status, _) = session_json(&fixture, &sid).await?;
  assert_eq!(
    status,
    StatusCode::UNAUTHORIZED,
    "failed exchange creates no session"
  );
  Ok(())
}

#[tokio::test]
async fn refresh_reuse_invalid_grant_clears_the_session() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  // First `/token` call (the exchange) succeeds; the refresh reuses a revoked
  // family member and is rejected.
  Mock::given(method("POST"))
    .and(path("/token"))
    .respond_with(token_ok("access-1", "refresh-1"))
    .up_to_n_times(1)
    .mount(&fake)
    .await;
  Mock::given(method("POST"))
    .and(path("/token"))
    .respond_with(ResponseTemplate::new(400).set_body_json(serde_json::json!({
      "error": "invalid_grant",
      "error_description": "refresh token reused",
    })))
    .mount(&fake)
    .await;
  let now = now_secs();
  mount_introspect(
    &fake,
    active_introspection(now + 300, now - 10, &fixture.jkt),
  )
  .await;

  let (state, sid) = start_flow(&fixture).await?;
  let sid = callback_flow(&fixture, &state, &sid).await?;
  let (_, json) = session_json(&fixture, &sid).await?;
  let csrf = json["csrf_token"]
    .as_str()
    .expect("csrf_token served")
    .to_owned();

  let response = send(
    fixture.app.clone(),
    post_request("/api/refresh", &cookie_for(&sid), &csrf, None),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::UNAUTHORIZED);
  let body = body_text(response).await?;
  assert!(
    body.contains("invalid_grant"),
    "expected the reuse code, got: {body}"
  );
  assert!(
    fixture.state.sessions().get(&sid).is_none(),
    "reuse must clear the session"
  );
  Ok(())
}

#[tokio::test]
async fn csrf_and_origin_rejections_leave_the_session_intact() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  mount_token(&fake, token_ok("access-1", "refresh-1")).await;
  let now = now_secs();
  mount_introspect(
    &fake,
    active_introspection(now + 300, now - 10, &fixture.jkt),
  )
  .await;

  let (state, sid) = start_flow(&fixture).await?;
  let sid = callback_flow(&fixture, &state, &sid).await?;
  let (_, json) = session_json(&fixture, &sid).await?;
  let csrf = json["csrf_token"]
    .as_str()
    .expect("csrf_token served")
    .to_owned();

  // Foreign `Origin` is rejected.
  let response = send(
    fixture.app.clone(),
    post_request(
      "/api/refresh",
      &cookie_for(&sid),
      &csrf,
      Some("https://evil.example"),
    ),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::FORBIDDEN);

  // Missing CSRF token is rejected.
  let response = send(
    fixture.app.clone(),
    Request::builder()
      .uri("/api/refresh")
      .method("POST")
      .header("cookie", cookie_for(&sid))
      .body(Body::empty())
      .expect("request builds"),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::FORBIDDEN);

  // Cross-site fetch metadata is rejected.
  let response = send(
    fixture.app.clone(),
    Request::builder()
      .uri("/api/logout")
      .method("POST")
      .header("cookie", cookie_for(&sid))
      .header("x-csrf-token", csrf.clone())
      .header("sec-fetch-site", "cross-site")
      .body(Body::empty())
      .expect("request builds"),
  )
  .await?;
  assert_eq!(response.status(), StatusCode::FORBIDDEN);

  assert!(
    fixture.state.sessions().get(&sid).is_some(),
    "rejected POSTs must not touch the session"
  );
  Ok(())
}

#[tokio::test]
async fn cookie_flags_are_hardened_through_the_flow() -> TestResult {
  let fake = MockServer::start().await;
  let (fixture, _dir) = fixture_app(&fake);
  mount_discovery(&fake, &fixture.issuer).await;
  mount_par(&fake).await;
  mount_token(&fake, token_ok("access-1", "refresh-1")).await;
  let now = now_secs();
  mount_introspect(
    &fake,
    active_introspection(now + 300, now - 10, &fixture.jkt),
  )
  .await;
  mount_revoke(&fake).await;

  // Start cookie: opaque id only, hardened attributes.
  let start = send(fixture.app.clone(), get_request("/oauth/start", None)).await?;
  let start_cookie = header_value(&start, "set-cookie");
  for expected in ["sid=", "Path=/", "HttpOnly", "SameSite=Lax"] {
    assert!(
      start_cookie.contains(expected),
      "start cookie misses {expected}: {start_cookie}"
    );
  }
  assert!(
    !start_cookie.contains("access-1"),
    "token in cookie: {start_cookie}"
  );
  let sid = sid_from_set_cookie(&start_cookie).expect("sid cookie");
  let state = fixture
    .state
    .pending()
    .pending_state_for_session(&sid)
    .expect("state bound to the session");

  // Login rotates the id with the same flags.
  let sid = callback_flow(&fixture, &state, &sid).await?;

  let (_, json) = session_json(&fixture, &sid).await?;
  let csrf = json["csrf_token"]
    .as_str()
    .expect("csrf_token served")
    .to_owned();
  let response = send(
    fixture.app.clone(),
    post_request("/api/logout", &cookie_for(&sid), &csrf, None),
  )
  .await?;
  let cleared = header_value(&response, "set-cookie");
  assert!(
    cleared.contains("Max-Age=0"),
    "logout must clear the cookie: {cleared}"
  );
  Ok(())
}

#[tokio::test]
async fn no_secret_reaches_logs_or_debug_output() {
  let line = server::http_client::loggable_request(
    "POST",
    "https://as.example/token?code=AUTH-C0DE",
    true,
    true,
  );
  let decorated = format!(
    "{line} secret={} token={}",
    server::http_client::redact_secret("CLIENT-S3CRET"),
    server::http_client::redact_secret("ACCESS-T0KEN"),
  );
  for sensitive in ["CLIENT-S3CRET", "ACCESS-T0KEN", "AUTH-C0DE"] {
    assert!(
      !decorated.contains(sensitive),
      "secret leaked into log line: {decorated:?}"
    );
  }

  let store = fixture_store();
  let created = store.create().expect("session creates");
  store.store_tokens(
    &created.id,
    Some(SecretString::from("ACCESS-S3CRET")),
    Some(SecretString::from("REFRESH-S3CRET")),
    Some("DPoP".to_owned()),
  );
  let rendered = format!("{:?}", store.get(&created.id).expect("session lives"));
  for sensitive in ["ACCESS-S3CRET", "REFRESH-S3CRET"] {
    assert!(
      !rendered.contains(sensitive),
      "secret leaked into session Debug: {rendered:?}"
    );
  }
  let cookie =
    server::session::set_cookie_value(&created.id, false, std::time::Duration::from_secs(60));
  assert!(!cookie.contains("ACCESS-S3CRET"));

  let csrf = created.csrf_token.expose_secret().to_owned();
  assert!(store.validate_csrf(&created.id, &csrf));
}

fn fixture_store() -> server::session::SessionStore {
  server::session::SessionStore::new(std::time::Duration::from_secs(3600))
}