package server_test

import (
	"bytes"
	"context"
	"net/http"
	"net/http/httptest"
	"net/url"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/audit"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/auth"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/config"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/httpx"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/mail"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/recovery"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/server"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/store"
	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/users"
)

// member is one enrolled user with a live session (the chain's four tiers).
type member struct {
	userID     int64
	identityID int64
	guid       string
	sessionID  string
	email      string
	role       users.Role
}

type recoveryHarness struct {
	t        *testing.T
	ctx      context.Context
	db       *store.DB
	users    *users.Store
	ids      *auth.IdentitiesService
	sessions *auth.SessionsService
	requests *recovery.Store
	mailer   *mail.Fake
	csrf     *httpx.CSRF
	pre      *httpx.PreSessionCSRF
	srv      *server.Server

	admin    member
	director member
	manager  member
	team     member
	peer     member // a second team member (same role as team)
}

func newRecoveryHarness(t *testing.T) *recoveryHarness {
	t.Helper()
	ctx := context.Background()

	db, err := store.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatalf("store.Open: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	if err := db.Migrate(); err != nil {
		t.Fatalf("Migrate: %v", err)
	}

	aud := audit.New(db.DB)
	us := users.New(db.DB, aud)

	sealer, err := auth.NewAEADSealer(bytes.Repeat([]byte{0x51}, auth.KeySize))
	if err != nil {
		t.Fatalf("NewAEADSealer: %v", err)
	}
	core := auth.New(db.DB, aud, auth.WithSealer(sealer))
	ids := core.Identities()
	sessions := core.Sessions()

	const (
		csrfKey      = "recovery-csrf-key-0123456789abcdef"
		cookieSecret = "recovery-cookie-secret-0123456789abcdef"
	)
	csrf, err := httpx.NewCSRF([]byte(csrfKey))
	if err != nil {
		t.Fatalf("NewCSRF: %v", err)
	}
	pre, err := httpx.NewPreSessionCSRF([]byte(cookieSecret), false)
	if err != nil {
		t.Fatalf("NewPreSessionCSRF: %v", err)
	}

	h := &recoveryHarness{
		t: t, ctx: ctx, db: db, users: us, ids: ids, sessions: sessions,
		mailer: mail.NewFake(), csrf: csrf, pre: pre,
	}
	h.requests = recovery.NewStore(db.DB, aud)

	// The chain, built top-down (D-019).
	h.admin = h.enroll(ctx, 0, "admin@example.com", "Admin", users.RoleAdmin)
	h.director = h.enroll(ctx, h.admin.userID, "director@example.com", "Director", users.RoleDirector)
	h.manager = h.enroll(ctx, h.director.userID, "manager@example.com", "Manager", users.RoleManager)
	h.team = h.enroll(ctx, h.manager.userID, "team@example.com", "Team", users.RoleTeam)
	h.peer = h.enroll(ctx, h.manager.userID, "peer@example.com", "Peer", users.RoleTeam)

	rec, err := recovery.New(recovery.Deps{
		Requests:   h.requests,
		Users:      us,
		Identities: ids,
		Mailer:     h.mailer,
		CSRF:       pre,
		Audit:      aud,
		BaseURL:    "https://myday.example.com",
		Logger:     nil,
		// M2s makes the notification asynchronous by default; these assertions
		// are about no-spam semantics, so run it synchronously for determinism.
		Dispatch: func(fn func()) { fn() },
	})
	if err != nil {
		t.Fatalf("recovery.New: %v", err)
	}

	reg := server.NewMapRegistry()
	reg.RegisterCore("home", server.Home)
	reg.RegisterModule(server.NewModule("home").
		SetDefault("dashboard", server.Home).
		AddRoute("home", "home", server.Home))
	server.RegisterRecoveryFlow(reg, rec)

	cfg := &config.Config{
		Server:   config.Server{Listen: "127.0.0.1:8080", BaseURL: "https://myday.example.com"},
		Database: config.Database{Path: db.Path()},
		Secrets:  config.Secrets{CSRFKey: csrfKey, CookieSecret: cookieSecret},
	}
	srv, err := server.New(server.Deps{
		Config: cfg, Resolver: ids, Registry: reg, Sessions: sessions,
		Identities: ids, Users: us, Audit: aud, CSRF: csrf, PreSession: pre,
		RoleGate: server.NewTiers(),
	})
	if err != nil {
		t.Fatalf("server.New: %v", err)
	}
	h.srv = srv
	return h
}

// enroll creates a user on the chain, activates an identity and mints a session.
func (h *recoveryHarness) enroll(ctx context.Context, creator int64, email, name string, role users.Role) member {
	h.t.Helper()
	uid, err := h.users.Create(ctx, creator, email, name, role)
	if err != nil {
		h.t.Fatalf("create %s: %v", role, err)
	}
	id, guid, err := h.ids.Mint(ctx, uid)
	if err != nil {
		h.t.Fatalf("Mint %s: %v", role, err)
	}
	if err := h.ids.Activate(ctx, id); err != nil {
		h.t.Fatalf("Activate %s: %v", role, err)
	}
	sess, err := h.sessions.Mint(ctx, id, "127.0.0.1", "test")
	if err != nil {
		h.t.Fatalf("session Mint %s: %v", role, err)
	}
	return member{userID: uid, identityID: id, guid: guid, sessionID: sess.ID, email: email, role: role}
}

func (h *recoveryHarness) preCSRF() (*http.Cookie, string) {
	h.t.Helper()
	tok, err := h.pre.Token()
	if err != nil {
		h.t.Fatalf("pre-session Token: %v", err)
	}
	return &http.Cookie{Name: httpx.PreSessionCookieName, Value: tok}, tok
}

// access posts the recovery request form (anonymous, A15).
func (h *recoveryHarness) access(email string) *httptest.ResponseRecorder {
	h.t.Helper()
	cookie, token := h.preCSRF()
	form := url.Values{"email": {email}, "csrf": {token}}
	req := httptest.NewRequest("POST", "/access?do=auth&action=recover", strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.AddCookie(cookie)
	rec := httptest.NewRecorder()
	h.srv.ServeHTTP(rec, req)
	return rec
}

// sessionCookie is the session cookie the door expects for this harness's
// transport. base_url is https here, so the cookie carries the `__Host-`
// prefix (L1s).
func (h *recoveryHarness) sessionCookie(id string) *http.Cookie {
	return &http.Cookie{Name: httpx.SessionCookieNameFor(true), Value: id}
}

// decide issues a session-gated approve/deny action as actor.
func (h *recoveryHarness) decide(action string, actor member, requestID int64) *httptest.ResponseRecorder {
	h.t.Helper()
	form := url.Values{
		"request": {strconv.FormatInt(requestID, 10)},
		"csrf":    {h.csrf.Token(actor.sessionID)},
	}
	req := httptest.NewRequest("POST", "/"+actor.guid+"?do=recovery&action="+action, strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.AddCookie(h.sessionCookie(actor.sessionID))
	rec := httptest.NewRecorder()
	h.srv.ServeHTTP(rec, req)
	return rec
}

// openRequest submits team's recovery request and returns its id.
func (h *recoveryHarness) openRequest(m member) recovery.Request {
	h.t.Helper()
	if rec := h.access(m.email); rec.Code != http.StatusOK {
		h.t.Fatalf("POST /access = %d, want 200", rec.Code)
	}
	req, err := h.requests.Pending(h.ctx, m.userID)
	if err != nil {
		h.t.Fatalf("Pending(%d): %v", m.userID, err)
	}
	return req
}

// auditActions returns the set of audit actions recorded.
func (h *recoveryHarness) auditActions(t *testing.T) map[string]bool {
	t.Helper()
	rows, err := h.db.Query(`SELECT action FROM audit_log`)
	if err != nil {
		t.Fatalf("read audit_log: %v", err)
	}
	defer rows.Close()
	got := map[string]bool{}
	for rows.Next() {
		var a string
		if err := rows.Scan(&a); err != nil {
			t.Fatalf("scan audit action: %v", err)
		}
		got[a] = true
	}
	if err := rows.Err(); err != nil {
		t.Fatalf("iterate audit_log: %v", err)
	}
	return got
}

// ── AC-2 ─────────────────────────────────────────────────────────────────────

// TestSpec007AC2_NoSelfApprovalOrLowerRole: the requester can never approve
// their own request, and a peer (same role) cannot either (D-019, AC-2).
func TestSpec007AC2_NoSelfApprovalOrLowerRole(t *testing.T) {
	h := newRecoveryHarness(t)
	req := h.openRequest(h.team)

	// The requester themselves -> forbidden. The body must be EXACTLY the
	// client error — a returned error would make the door append a 500 on top
	// of an already-written response.
	if rec := h.decide("approve", h.team, req.ID); rec.Code != http.StatusForbidden {
		t.Errorf("self-approval = %d, want 403 (AC-2)", rec.Code)
	} else if got := rec.Body.String(); strings.TrimSpace(got) != "forbidden" {
		t.Errorf("self-approval body = %q, want exactly %q", got, "forbidden")
	}
	// A peer (same role) -> forbidden.
	if rec := h.decide("approve", h.peer, req.ID); rec.Code != http.StatusForbidden {
		t.Errorf("peer approval = %d, want 403 (AC-2)", rec.Code)
	}

	// Nothing changed: the identity is still active, the request still pending.
	idn, err := h.ids.ByGUID(h.ctx, h.team.guid)
	if err != nil || idn.Status != auth.StatusActive {
		t.Errorf("identity after a refused approval = %+v, want still active (AC-2)", idn)
	}
	still, err := h.requests.Get(h.ctx, req.ID)
	if err != nil || still.Status != recovery.StatusPending {
		t.Errorf("request after a refused approval = %+v, want pending (AC-2)", still)
	}
}

// TestSpec007AC2_R7_ChainAuthority: the recovery authority is the CHAIN (R-7).
// A director in a DIFFERENT subtree is a role above a team member but not on
// their manager line, so they may NOT approve; the admin (the root) may.
func TestSpec007AC2_R7_ChainAuthority(t *testing.T) {
	h := newRecoveryHarness(t)

	// A second director, created by the admin: role-above team, but NOT an
	// ancestor of team (team -> manager -> director -> admin).
	directorB := h.enroll(h.ctx, h.admin.userID, "director2@example.com", "Director2", users.RoleDirector)

	req := h.openRequest(h.team)

	// Role-above but off the chain -> forbidden (R-7's correction).
	if rec := h.decide("approve", directorB, req.ID); rec.Code != http.StatusForbidden {
		t.Errorf("non-ancestor director approval = %d, want 403 (R-7)", rec.Code)
	}
	// The request is untouched by the refusal.
	if still, err := h.requests.Get(h.ctx, req.ID); err != nil || still.Status != recovery.StatusPending {
		t.Errorf("request after a refused off-chain approval = %+v, want pending (R-7)", still)
	}

	// The admin is the root of the chain and may approve.
	if rec := h.decide("approve", h.admin, req.ID); rec.Code != http.StatusOK {
		t.Errorf("admin approval = %d, want 200 (R-7)", rec.Code)
	}
}

// ── AC-3 ─────────────────────────────────────────────────────────────────────

// TestSpec007AC3_ApprovalRotatesIdentity: an approver on the requester's chain
// revokes the old identity and all its sessions and mints a NEW GUID, then
// emails the enrolment link (D-007, AC-3).
func TestSpec007AC3_ApprovalRotatesIdentity(t *testing.T) {
	h := newRecoveryHarness(t)
	req := h.openRequest(h.team)

	rec := h.decide("approve", h.manager, req.ID) // manager is above team
	if rec.Code != http.StatusOK {
		t.Fatalf("approve = %d, want 200 (body %q)", rec.Code, rec.Body.String())
	}

	// The OLD identity is revoked and its GUID tombstoned.
	old, err := h.ids.ByGUID(h.ctx, h.team.guid)
	if err != nil {
		t.Fatalf("ByGUID(old): %v", err)
	}
	if old.Status != auth.StatusRevoked {
		t.Errorf("old identity status = %s, want revoked (AC-3)", old.Status)
	}
	// Every session of the old identity is dead.
	if _, err := h.sessions.Validate(h.ctx, h.team.sessionID); err == nil {
		t.Error("a pre-approval session survived the rotation (AC-3)")
	}

	// A NEW GUID is minted, pending enrollment, under the same user.
	fresh, err := h.ids.ByUserID(h.ctx, h.team.userID)
	if err != nil {
		t.Fatalf("ByUserID: %v", err)
	}
	if fresh.GUID == h.team.guid {
		t.Error("approval reissued the old GUID (AC-3)")
	}
	if fresh.Status != auth.StatusPendingEnrollment {
		t.Errorf("new identity status = %s, want pending_enrollment (AC-3)", fresh.Status)
	}

	// The enrolment link reached the address on record.
	found := false
	for _, m := range h.mailer.To(h.team.email) {
		if strings.Contains(m.Body, fresh.GUID) {
			found = true
		}
	}
	if !found {
		t.Errorf("no enrolment email carrying the new GUID reached %s (AC-3)", h.team.email)
	}

	// The request is approved.
	done, err := h.requests.Get(h.ctx, req.ID)
	if err != nil || done.Status != recovery.StatusApproved {
		t.Errorf("request = %+v, want approved (AC-3)", done)
	}
}

// ── AC-4 ─────────────────────────────────────────────────────────────────────

// TestSpec007AC4_AccessIsGeneric: /access never reveals whether the email
// matched — the same status and the same body either way (A3, AC-4).
func TestSpec007AC4_AccessIsGeneric(t *testing.T) {
	h := newRecoveryHarness(t)

	hit := h.access(h.team.email)
	miss := h.access("nobody@example.com")

	if hit.Code != http.StatusOK || miss.Code != http.StatusOK {
		t.Fatalf("handle codes = %d/%d, want 200/200", hit.Code, miss.Code)
	}
	if hit.Body.String() != miss.Body.String() {
		t.Errorf("the /access response differs on a hit vs a miss:\nhit:  %q\nmiss: %q",
			hit.Body.String(), miss.Body.String())
	}
	if !strings.Contains(hit.Body.String(), "If a record exists") {
		t.Errorf("the /access notice is not generic: %q", hit.Body.String())
	}
}

// ── AC-6 ─────────────────────────────────────────────────────────────────────

// TestSpec007AC6_RecoveryIsAudited: request, approve, deny and the identity
// rotation are all recorded (A11, AC-6).
func TestSpec007AC6_RecoveryIsAudited(t *testing.T) {
	h := newRecoveryHarness(t)

	// approve
	req := h.openRequest(h.team)
	if rec := h.decide("approve", h.manager, req.ID); rec.Code != http.StatusOK {
		t.Fatalf("approve = %d, want 200", rec.Code)
	}
	// deny
	req2 := h.openRequest(h.manager)
	if rec := h.decide("deny", h.director, req2.ID); rec.Code != http.StatusOK {
		t.Fatalf("deny = %d, want 200", rec.Code)
	}

	got := h.auditActions(t)
	for _, want := range []string{
		"recovery.request",
		"recovery.approve",
		"recovery.deny",
		"identity.rotate",
	} {
		if !got[want] {
			t.Errorf("audit log is missing %q (AC-6); got %v", want, got)
		}
	}
}

// ── supporting behaviour ─────────────────────────────────────────────────────

// TestSpec007AccessIssuesPreSessionCSRF: the anonymous /access form carries the
// signed pre-session token (A15) and the action without it is refused.
func TestSpec007AccessIssuesPreSessionCSRF(t *testing.T) {
	h := newRecoveryHarness(t)

	rec := request(h.srv, "GET", "/access")
	if rec.Code != http.StatusOK {
		t.Fatalf("GET /access = %d, want 200", rec.Code)
	}
	if !hasCookie(rec, httpx.PreSessionCookieName) {
		t.Error("GET /access issued no pre-session CSRF cookie (A15)")
	}
	if got := rec.Header().Get("Cache-Control"); got != "no-store" {
		t.Errorf("GET /access Cache-Control = %q, want no-store", got)
	}

	// Without the double-submit token the action is refused (A15).
	req := httptest.NewRequest("POST", "/access?do=auth&action=recover",
		strings.NewReader(url.Values{"email": {h.team.email}}.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	rr := httptest.NewRecorder()
	h.srv.ServeHTTP(rr, req)
	if rr.Code != http.StatusForbidden {
		t.Errorf("recovery request without CSRF = %d, want 403 (A15)", rr.Code)
	}
}

// TestSpec007_RepeatRequestDoesNotRenotify: a second POST for the same user
// reuses the pending request and does NOT email the chain again (no spam).
func TestSpec007_RepeatRequestDoesNotRenotify(t *testing.T) {
	h := newRecoveryHarness(t)

	if rec := h.access(h.team.email); rec.Code != http.StatusOK {
		t.Fatalf("first POST /access = %d, want 200", rec.Code)
	}
	first := len(h.mailer.Sent())
	if first == 0 {
		t.Fatal("the first request sent no notification")
	}

	if rec := h.access(h.team.email); rec.Code != http.StatusOK {
		t.Fatalf("second POST /access = %d, want 200", rec.Code)
	}
	if got := len(h.mailer.Sent()); got != first {
		t.Errorf("a repeated request re-notified the chain: %d messages, want %d", got, first)
	}
}

// TestSpec007_SecondDecisionRefused: the request is claimed atomically — a
// second approve/deny is refused and does not rotate a second time.
func TestSpec007_SecondDecisionRefused(t *testing.T) {
	h := newRecoveryHarness(t)
	req := h.openRequest(h.team)

	if rec := h.decide("approve", h.manager, req.ID); rec.Code != http.StatusOK {
		t.Fatalf("first approve = %d, want 200 (body %q)", rec.Code, rec.Body.String())
	}
	if rec := h.decide("approve", h.director, req.ID); rec.Code != http.StatusConflict {
		t.Errorf("second approve = %d, want 409 (already decided)", rec.Code)
	}

	// The user has exactly one live (pending) identity — no double rotation.
	var n int
	if err := h.db.QueryRow(
		`SELECT count(*) FROM identities WHERE user_id = ? AND status <> 'revoked'`, h.team.userID,
	).Scan(&n); err != nil {
		t.Fatalf("count live identities: %v", err)
	}
	if n != 1 {
		t.Errorf("live identities = %d, want exactly 1 (no double rotation)", n)
	}
}

// TestSpec007_ExpiredRequestCannotBeApproved: a request past the ~72h window
// is expired and refused (SPEC-007 §4).
func TestSpec007_ExpiredRequestCannotBeApproved(t *testing.T) {
	h := newRecoveryHarness(t)
	req := h.openRequest(h.team)

	// Age the request well past the TTL.
	past := store.FormatTime(time.Now().Add(-100 * time.Hour))
	if _, err := h.db.Exec(`UPDATE recovery_requests SET requested_at = ? WHERE request_id = ?`, past, req.ID); err != nil {
		t.Fatalf("age request: %v", err)
	}

	rec := h.decide("approve", h.manager, req.ID)
	if rec.Code != http.StatusGone {
		t.Errorf("approve an expired request = %d, want 410", rec.Code)
	}
	// The identity was NOT rotated.
	idn, err := h.ids.ByGUID(h.ctx, h.team.guid)
	if err != nil || idn.Status != auth.StatusActive {
		t.Errorf("identity after an expired approval = %+v, want still active", idn)
	}
	stored, err := h.requests.Get(h.ctx, req.ID)
	if err != nil || stored.Status != recovery.StatusExpired {
		t.Errorf("request = %+v, want expired", stored)
	}
}

// TestSpec007DenyDoesNotRotate: a denial leaves the requester's identity intact.
func TestSpec007DenyDoesNotRotate(t *testing.T) {
	h := newRecoveryHarness(t)
	req := h.openRequest(h.team)

	if rec := h.decide("deny", h.director, req.ID); rec.Code != http.StatusOK {
		t.Fatalf("deny = %d, want 200", rec.Code)
	}
	idn, err := h.ids.ByGUID(h.ctx, h.team.guid)
	if err != nil || idn.Status != auth.StatusActive {
		t.Errorf("identity after a denial = %+v, want still active", idn)
	}
	done, err := h.requests.Get(h.ctx, req.ID)
	if err != nil || done.Status != recovery.StatusDenied {
		t.Errorf("request = %+v, want denied", done)
	}
}