package httpapi

import (
	"context"
	"errors"
	"net/http"
	"sort"
	"strings"

	"github.com/descrybe/descrybe-v2/apps/api/internal/auth"
	"github.com/descrybe/descrybe-v2/apps/api/internal/billing"
	"github.com/go-chi/chi/v5"
	"github.com/google/uuid"
)

const defaultDevPassword = "DemoPass123!"

func isLocalDemoEmail(email string) bool {
	switch strings.ToLower(strings.TrimSpace(email)) {
	case "demo@descrybe.local", "demo@descrybe.test":
		return true
	default:
		return false
	}
}

// resolveDevImpersonationActor returns the privileged actor allowed to drive non-prod
// user switching: the current full admin/demo user, or the stored impersonator.
func (s *Server) resolveDevImpersonationActor(ctx context.Context) (actorID uuid.UUID, ok bool, err error) {
	if s.Config.IsProduction() {
		return uuid.Nil, false, nil
	}
	uid, hasUID := UserIDFromContext(ctx)
	if !hasUID || uid == uuid.Nil {
		return uuid.Nil, false, nil
	}
	if s.Auth == nil {
		return uuid.Nil, false, errors.New("auth unavailable")
	}

	access, err := s.checkStaffAccess(ctx, uid)
	if err != nil {
		return uuid.Nil, false, err
	}
	if access.FullAdmin {
		return uid, true, nil
	}
	user, err := s.Auth.GetUser(ctx, uid)
	if err == nil && isLocalDemoEmail(user.Email) {
		return uid, true, nil
	}

	impStr := strings.TrimSpace(s.Sessions.GetString(ctx, auth.SessionImpersonatorIDKey))
	if impStr == "" {
		return uuid.Nil, false, nil
	}
	impID, err := uuid.Parse(impStr)
	if err != nil || impID == uuid.Nil {
		return uuid.Nil, false, nil
	}
	impAccess, err := s.checkStaffAccess(ctx, impID)
	if err != nil {
		return uuid.Nil, false, err
	}
	if impAccess.FullAdmin {
		return impID, true, nil
	}
	impUser, err := s.Auth.GetUser(ctx, impID)
	if err == nil && isLocalDemoEmail(impUser.Email) {
		return impID, true, nil
	}
	return uuid.Nil, false, nil
}

// handleAdminDevSetPassword sets a known local password for any active user.
// Blocked in production. Intended for @legacy.local migrated accounts (invite emails skip those).
func (s *Server) handleAdminDevSetPassword(w http.ResponseWriter, r *http.Request) {
	if s.Config.IsProduction() {
		Error(w, http.StatusNotFound, "not found")
		return
	}
	if s.Auth == nil {
		Error(w, http.StatusServiceUnavailable, "auth unavailable")
		return
	}
	id, err := uuid.Parse(chi.URLParam(r, "id"))
	if err != nil {
		Error(w, http.StatusBadRequest, "invalid id")
		return
	}
	var body struct {
		Password string `json:"password"`
	}
	_ = DecodeJSONOptional(r, &body)
	password := body.Password
	if strings.TrimSpace(password) == "" {
		password = defaultDevPassword
	}
	if len(password) < 8 {
		Error(w, http.StatusBadRequest, "password must be at least 8 characters")
		return
	}
	user, err := s.Auth.GetUser(r.Context(), id)
	if err != nil {
		Error(w, http.StatusNotFound, "user not found")
		return
	}
	if !user.IsActive {
		Error(w, http.StatusBadRequest, "user is inactive")
		return
	}
	if err := s.Auth.ForceSetPassword(r.Context(), id, password); err != nil {
		if errors.Is(err, auth.ErrUserNotFound) {
			Error(w, http.StatusNotFound, "user not found")
			return
		}
		LogAndError(w, http.StatusInternalServerError, "could not set password", err)
		return
	}
	JSON(w, http.StatusOK, map[string]any{
		"ok":      true,
		"user_id": id,
		"email":   user.Email,
		"hint":    "Password set for local login. Omit body.password to use the built-in local default.",
	})
}

// handleAdminDevImpersonate swaps the current session to the target user (non-production only).
func (s *Server) handleAdminDevImpersonate(w http.ResponseWriter, r *http.Request) {
	if s.Config.IsProduction() {
		Error(w, http.StatusNotFound, "not found")
		return
	}
	if s.Auth == nil {
		Error(w, http.StatusServiceUnavailable, "auth unavailable")
		return
	}
	actorID, allowed, err := s.resolveDevImpersonationActor(r.Context())
	if err != nil {
		LogAndError(w, http.StatusInternalServerError, "could not authorize user switch", err)
		return
	}
	if !allowed {
		Error(w, http.StatusForbidden, "user switch not allowed")
		return
	}
	id, err := uuid.Parse(chi.URLParam(r, "id"))
	if err != nil {
		Error(w, http.StatusBadRequest, "invalid id")
		return
	}
	adminID, ok := UserIDFromContext(r.Context())
	if !ok || adminID == uuid.Nil {
		Error(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	if adminID == id {
		Error(w, http.StatusBadRequest, "already signed in as this user")
		return
	}
	user, err := s.Auth.GetUser(r.Context(), id)
	if err != nil {
		Error(w, http.StatusNotFound, "user not found")
		return
	}
	if !user.IsActive {
		Error(w, http.StatusBadRequest, "user is inactive")
		return
	}
	companies, err := s.Auth.ListUserCompanies(r.Context(), id)
	if err != nil {
		LogAndError(w, http.StatusInternalServerError, "could not list companies", err)
		return
	}
	var companyID uuid.UUID
	if len(companies) > 0 {
		companyID = companies[0].ID
	}
	if err := s.beginImpersonatedSession(r.Context(), id, companyID, actorID); err != nil {
		Error(w, http.StatusInternalServerError, "session start failed")
		return
	}
	JSON(w, http.StatusOK, map[string]any{
		"ok":         true,
		"user":       user,
		"company_id": companyID,
		"companies":  companies,
		"hint":       "Session switched. Reload the app to view this user's tenant context.",
	})
}

// handleAdminDevStopImpersonate restores the session to the original admin/demo actor.
func (s *Server) handleAdminDevStopImpersonate(w http.ResponseWriter, r *http.Request) {
	if s.Config.IsProduction() {
		Error(w, http.StatusNotFound, "not found")
		return
	}
	if s.Auth == nil {
		Error(w, http.StatusServiceUnavailable, "auth unavailable")
		return
	}
	actorID, allowed, err := s.resolveDevImpersonationActor(r.Context())
	if err != nil {
		LogAndError(w, http.StatusInternalServerError, "could not authorize stop impersonate", err)
		return
	}
	if !allowed {
		Error(w, http.StatusForbidden, "user switch not allowed")
		return
	}
	impStr := strings.TrimSpace(s.Sessions.GetString(r.Context(), auth.SessionImpersonatorIDKey))
	if impStr == "" {
		Error(w, http.StatusBadRequest, "not impersonating")
		return
	}
	impID, err := uuid.Parse(impStr)
	if err != nil || impID == uuid.Nil {
		Error(w, http.StatusBadRequest, "invalid impersonator")
		return
	}
	if impID != actorID {
		// Prefer the stored impersonator when it is still the privileged actor.
		impAccess, aerr := s.checkStaffAccess(r.Context(), impID)
		if aerr != nil || !impAccess.FullAdmin {
			impUser, uerr := s.Auth.GetUser(r.Context(), impID)
			if uerr != nil || !isLocalDemoEmail(impUser.Email) {
				Error(w, http.StatusForbidden, "user switch not allowed")
				return
			}
		}
	}
	user, err := s.Auth.GetUser(r.Context(), impID)
	if err != nil {
		Error(w, http.StatusNotFound, "impersonator not found")
		return
	}
	if !user.IsActive {
		Error(w, http.StatusBadRequest, "impersonator is inactive")
		return
	}
	companies, err := s.Auth.ListUserCompanies(r.Context(), impID)
	if err != nil {
		LogAndError(w, http.StatusInternalServerError, "could not list companies", err)
		return
	}
	var companyID uuid.UUID
	if len(companies) > 0 {
		companyID = companies[0].ID
	}
	// Clear impersonation then start a normal session as the actor.
	s.Sessions.Remove(r.Context(), auth.SessionImpersonatorIDKey)
	if err := s.beginAuthenticatedSession(r.Context(), impID, companyID); err != nil {
		Error(w, http.StatusInternalServerError, "session start failed")
		return
	}
	JSON(w, http.StatusOK, map[string]any{
		"ok":         true,
		"user":       user,
		"company_id": companyID,
		"companies":  companies,
		"hint":       "Returned to original session. Reload the app.",
	})
}

// primaryA1LegacyUserID is the Clerk user_id for the A1 contact we care about in local demos
// (migrated as …@legacy.local). Used only for non-prod switcher labels.
const primaryA1LegacyUserID = "user_30AqqJ8uepxvPUzDSqy81U5w6Ll"

type switchableUserRow struct {
	ID               uuid.UUID `json:"id"`
	Email            string    `json:"email"`
	Name             *string   `json:"name"`
	LegacyUserID     *string   `json:"legacy_user_id,omitempty"`
	MembershipRole   string    `json:"membership_role,omitempty"`
	CompanyID        uuid.UUID `json:"company_id"`
	CompanyName      string    `json:"company_name"`
	CompanyLabel     string    `json:"company_label"`
	Label            string    `json:"label"`
	Subtitle         string    `json:"subtitle"`
	IsDemoAdmin      bool      `json:"is_demo_admin"`
	IsPrimaryA1      bool      `json:"is_primary_a1"`
	ClerkSuffix      string    `json:"clerk_suffix,omitempty"`
}

func companyDisplayLabel(companyName, legacyCompanyID string) string {
	name := strings.TrimSpace(companyName)
	if isA1LegacyCompany(legacyCompanyID, name) {
		// Prefer live company name when already A1 Slovenija; never fake "Local Demo Co".
		if name != "" && !strings.EqualFold(name, "Local Demo Co") {
			return name
		}
		return "A1 Slovenija"
	}
	if name == "" {
		return "Unknown company"
	}
	return name
}

func clerkIDFromLegacy(email string, legacyUserID *string) string {
	if legacyUserID != nil {
		if id := strings.TrimSpace(*legacyUserID); id != "" {
			return id
		}
	}
	email = strings.TrimSpace(strings.ToLower(email))
	if strings.HasSuffix(email, "@legacy.local") {
		return strings.TrimSuffix(email, "@legacy.local")
	}
	return ""
}

func shortClerkSuffix(clerkID string) string {
	id := strings.TrimSpace(clerkID)
	if id == "" {
		return ""
	}
	const n = 8
	if len(id) <= n {
		return id
	}
	return id[len(id)-n:]
}

func isPrimaryA1User(email, clerkID string) bool {
	emailNorm := strings.TrimSpace(strings.ToLower(email))
	if emailNorm == "a1-primary@descrybe.local" {
		return true
	}
	if strings.EqualFold(strings.TrimSpace(clerkID), primaryA1LegacyUserID) {
		return true
	}
	target := strings.ToLower(primaryA1LegacyUserID)
	local := emailNorm
	if i := strings.IndexByte(local, '@'); i > 0 {
		local = local[:i]
	}
	return local == target
}

// isA1LegacyCompany is true when the membership company maps to MySQL A1 Slovenija
// (legacy_company_id 97e1a309-…, dump name, or the old Local Demo Co rename).
// isA1LegacyCompany is true for non-prod switcher labels when the membership
// company maps to migrated A1 (immutable legacy_company_id) OR known dump/demo
// display names. Name matches are UI-only — billing cohort uses IsA1CohortCompany.
func isA1LegacyCompany(legacyCompanyID, companyName string) bool {
	if billing.IsA1CohortCompany(legacyCompanyID, companyName) {
		return true
	}
	n := strings.TrimSpace(companyName)
	return strings.EqualFold(n, "A1 Slovenija") ||
		strings.EqualFold(n, "Local Demo Co") ||
		strings.EqualFold(n, "A1")
}

// a1SwitcherLabel builds dump-truth labels. MySQL profiles have no human names/emails —
// only Clerk user_id — so we show "A1 · …<clerkSuffix>".
func a1SwitcherLabel(clerkSuffix string) string {
	if strings.TrimSpace(clerkSuffix) != "" {
		return "A1 · …" + clerkSuffix
	}
	return "A1 · A1 Slovenija"
}

func enrichSwitchableUser(u *switchableUserRow, legacyCompanyID string) {
	u.CompanyLabel = companyDisplayLabel(u.CompanyName, legacyCompanyID)
	clerkID := clerkIDFromLegacy(u.Email, u.LegacyUserID)
	u.ClerkSuffix = shortClerkSuffix(clerkID)
	u.IsDemoAdmin = isLocalDemoEmail(u.Email)
	onA1 := isA1LegacyCompany(legacyCompanyID, u.CompanyName)
	u.IsPrimaryA1 = onA1 && isPrimaryA1User(u.Email, clerkID)

	switch {
	case u.IsDemoAdmin:
		u.Label = "Demo admin"
		u.Subtitle = u.Email
	case onA1 && (u.IsPrimaryA1 || clerkID != ""):
		// Dump-confirmed A1 members (no human name in MySQL profiles/admin_users).
		u.Label = a1SwitcherLabel(u.ClerkSuffix)
		if clerkID != "" {
			u.Subtitle = "A1 Slovenija · " + clerkID
		} else {
			u.Subtitle = "A1 Slovenija · " + u.Email
		}
	default:
		if u.Name != nil && strings.TrimSpace(*u.Name) != "" {
			u.Label = strings.TrimSpace(*u.Name)
		} else {
			u.Label = u.Email
		}
		u.Subtitle = u.Email
	}
}

// handleAdminDevListSwitchableUsers lists active users with a preferred company label
// for the header user-switch dropdown (non-production only).
func (s *Server) handleAdminDevListSwitchableUsers(w http.ResponseWriter, r *http.Request) {
	if s.Config.IsProduction() {
		Error(w, http.StatusNotFound, "not found")
		return
	}
	if s.Pool == nil {
		Error(w, http.StatusServiceUnavailable, "database unavailable")
		return
	}
	_, allowed, err := s.resolveDevImpersonationActor(r.Context())
	if err != nil {
		LogAndError(w, http.StatusInternalServerError, "could not authorize user list", err)
		return
	}
	if !allowed {
		Error(w, http.StatusForbidden, "user switch not allowed")
		return
	}

	activeCompanyID := uuid.Nil
	if cidStr := strings.TrimSpace(s.Sessions.GetString(r.Context(), auth.SessionCompanyIDKey)); cidStr != "" {
		if cid, err := uuid.Parse(cidStr); err == nil {
			activeCompanyID = cid
		}
	}

	rows, err := s.Pool.Query(r.Context(), `
		SELECT DISTINCT ON (u.id)
			u.id, u.email, u.name, u.legacy_user_id, m.role, c.id, c.name, COALESCE(c.legacy_company_id, '')
		FROM users u
		INNER JOIN memberships m ON m.user_id = u.id AND m.status = 'active'
		INNER JOIN companies c ON c.id = m.company_id
		WHERE u.is_active = true
		ORDER BY u.id,
			CASE WHEN c.id = $1 THEN 0 ELSE 1 END,
			CASE WHEN COALESCE(c.legacy_company_id, '') = $2 THEN 0
			     WHEN c.name IN ('A1 Slovenija', 'Local Demo Co') THEN 0
			     ELSE 1 END,
			c.name ASC`, activeCompanyID, billing.A1LegacyCompanyID)
	if err != nil {
		LogAndError(w, http.StatusInternalServerError, "list failed", err)
		return
	}
	defer rows.Close()

	out := make([]switchableUserRow, 0)
	for rows.Next() {
		var u switchableUserRow
		var legacyCompanyID string
		if err := rows.Scan(
			&u.ID, &u.Email, &u.Name, &u.LegacyUserID, &u.MembershipRole,
			&u.CompanyID, &u.CompanyName, &legacyCompanyID,
		); err != nil {
			Error(w, http.StatusInternalServerError, "scan failed")
			return
		}
		enrichSwitchableUser(&u, legacyCompanyID)
		out = append(out, u)
	}
	if err := rows.Err(); err != nil {
		Error(w, http.StatusInternalServerError, "list failed")
		return
	}

	sort.SliceStable(out, func(i, j int) bool {
		ai := out[i].CompanyID == activeCompanyID
		aj := out[j].CompanyID == activeCompanyID
		if ai != aj {
			return ai
		}
		if out[i].CompanyLabel != out[j].CompanyLabel {
			return out[i].CompanyLabel < out[j].CompanyLabel
		}
		// Demo admin + primary A1 first within a company group.
		rank := func(u switchableUserRow) int {
			if u.IsDemoAdmin {
				return 0
			}
			if u.IsPrimaryA1 {
				return 1
			}
			return 2
		}
		ri, rj := rank(out[i]), rank(out[j])
		if ri != rj {
			return ri < rj
		}
		return strings.ToLower(out[i].Label) < strings.ToLower(out[j].Label)
	})

	payload := map[string]any{"users": out}
	if impStr := strings.TrimSpace(s.Sessions.GetString(r.Context(), auth.SessionImpersonatorIDKey)); impStr != "" {
		payload["impersonating"] = true
		if impID, err := uuid.Parse(impStr); err == nil {
			if impUser, err := s.Auth.GetUser(r.Context(), impID); err == nil {
				payload["impersonator"] = map[string]any{
					"id":    impUser.ID,
					"email": impUser.Email,
					"name":  impUser.Name,
				}
			}
		}
	}
	JSON(w, http.StatusOK, payload)
}