package server

import (
	"context"
	"errors"
	"net/http"
	"time"

	"gitea.meghsakha.com/platform/tenant-registry/internal/keycloak"
	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
)

// membershipItem is one tenant a user belongs to. Source records which
// system produced the authoritative half: "registry" when the tenant exists
// here (status/plan/products come from our tables), "keycloak" when only
// the attribute projection knows it (e.g. a tenant seeded directly in the
// realm that the registry has not onboarded yet).
type membershipItem struct {
	keycloak.Claims
	Source string `json:"source"`
}

type membershipsResp struct {
	UserID      string           `json:"user_id"`
	Memberships []membershipItem `json:"memberships"`
}

// getUserMemberships is GET /v1/users/{id}/memberships — the membership
// authority endpoint (ratified auth design, model B2). Product backends
// call it to answer "which tenants does this JWT subject belong to, with
// which roles", instead of trusting token claims or client headers.
//
// Resolution: Keycloak (via the Adapter) supplies user→tenant links and
// org_roles; where the tenant is registered here, status, plan, and
// product entitlements are overridden from the registry tables, which are
// authoritative for lifecycle and billing state.
func (s *Server) getUserMemberships(w http.ResponseWriter, r *http.Request) {
	userID := r.PathValue("id")
	if userID == "" {
		writeError(w, http.StatusBadRequest, "invalid_input", "user id required")
		return
	}

	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	claims, err := s.Keycloak.Memberships(ctx, userID)
	if err != nil {
		switch {
		case errors.Is(err, keycloak.ErrUserNotFound):
			writeError(w, http.StatusNotFound, "not_found", "user does not exist")
		case errors.Is(err, keycloak.ErrUnavailable), errors.Is(err, keycloak.ErrUnauthorized):
			writeError(w, http.StatusServiceUnavailable, "keycloak_unavailable", err.Error())
		default:
			writeError(w, http.StatusInternalServerError, "internal", err.Error())
		}
		return
	}

	items := make([]membershipItem, 0, len(claims))
	for _, c := range claims {
		items = append(items, s.enrichMembership(ctx, c))
	}
	writeJSON(w, http.StatusOK, membershipsResp{UserID: userID, Memberships: items})
}

// enrichMembership overrides the Keycloak attribute projection with
// registry truth when the tenant is known here. Lookup prefers the slug —
// the attribute tenant_id predates the registry for hand-seeded dev users
// and may not be a registry id.
func (s *Server) enrichMembership(ctx context.Context, c keycloak.Claims) membershipItem {
	var (
		t   *store.Tenant
		err error
	)
	if c.TenantSlug != "" {
		t, err = s.Store.GetTenantBySlug(ctx, c.TenantSlug)
	} else {
		t, err = s.Store.GetTenant(ctx, c.TenantID)
	}
	if err != nil || t == nil {
		return membershipItem{Claims: c, Source: "keycloak"}
	}

	products := []string{}
	if tps, perr := s.Store.ListTenantProducts(ctx, t.ID); perr == nil {
		for _, p := range tps {
			if p.Enabled {
				products = append(products, p.Product)
			}
		}
	}
	return membershipItem{
		Claims: keycloak.Claims{
			TenantID:     t.ID,
			TenantSlug:   t.Slug,
			OrgRoles:     c.OrgRoles, // roles stay Keycloak-owned
			Products:     products,
			Plan:         t.Plan,
			TenantStatus: t.Status,
		},
		Source: "registry",
	}
}