package server

import (
	"context"
	"database/sql"
	"errors"
	"log/slog"
	"net/http"
	"strconv"

	"git.coopcloud.tech/wiki-cafe/member-console/internal/entitlements"
	"git.coopcloud.tech/wiki-cafe/member-console/internal/web"
)

// EntitlementSetViewModel represents an entitlement set for operator template rendering.
type EntitlementSetViewModel struct {
	SetID       string
	Name        string
	Description string
	IsActive    bool
	RuleCount   int
	CreatedAt   string
}

// EntitlementSetsData holds data for the entitlement sets list partial.
type EntitlementSetsData struct {
	EntitlementSets []EntitlementSetViewModel
	FieldErrors     web.FieldErrors
	Success         string
	Error           string
	// Empty drives the list's empty state via the shared "emptyState"
	// define (ux-first-run 3.4). Entitlement sets are never blocked (they
	// have no prerequisite of their own), so this is always the not-blocked
	// shape; the copy carries the two-ended dependency purpose (rules feed
	// in, products consume it) so it survives past a bare "No X found."
	Empty EmptyStateParams
}

// EntitlementSetEditData holds data for the entitlement set edit form.
type EntitlementSetEditData struct {
	EntitlementSet EntitlementSetViewModel
	FieldErrors    web.FieldErrors
	Success        string
	Error          string
}

// RuleViewModel represents an entitlement set rule for template rendering.
type RuleViewModel struct {
	RuleID          string
	RuleType        string
	ResourceKey     string
	ResourceValue   int64
	ResourcePerUnit bool
	StackingPolicy  string
	IsActive        bool
	// IsLiveBacking is true when this rule's resource key currently backs a
	// materialized entitlement some pool actively holds (a numeric
	// contribution from a live provision, or a granted boolean key) — the
	// Delete control's inline consequence copy only renders for these.
	IsLiveBacking bool
}

// EntitlementSetRulesData holds data for the rules detail partial.
type EntitlementSetRulesData struct {
	EntitlementSet EntitlementSetViewModel
	Rules          []RuleViewModel
	ResourceKeys   []ResourceKeyOption
	RuleFields     RuleFieldsData
	FieldErrors    web.FieldErrors
	Success        string
	Error          string
}

// RuleFieldsData drives the kind-branched fields region of the add-rule form
// (operator_entitlement_set_rule_fields.html). SelectedKind is "" (no key
// chosen yet — hint state), "boolean", or "numeric".
type RuleFieldsData struct {
	SelectedKey  string
	SelectedKind string
	FieldErrors  web.FieldErrors
}

// ResourceKeyOption represents a resource key for dropdown selection.
type ResourceKeyOption struct {
	ResourceKey string
	DisplayName string
}

// EntitlementSetDetailData is the body data for the addressable per-entitlement-set
// composite page (operator_entitlement_set_detail.html). It co-locates the edit
// form and the rules manager on one URL; the composite template renders each
// sub-section via its existing partial.
type EntitlementSetDetailData struct {
	Edit  EntitlementSetEditData
	Rules EntitlementSetRulesData
	Error string
}

// entitlementSetNameConstraints maps the name-uniqueness constraint (finding
// #40; baked into the 00001_init.sql baseline, not a later migration) to a
// friendly field error so a duplicate name renders on the "name" input
// instead of leaking a 23505 into the banner.
var entitlementSetNameConstraints = web.ConstraintMessages{
	"uq_entitlement_sets_name": {Field: "name", Message: "That name is already in use. Choose a different name."},
}

// allowedStackingPolicies is the set of stacking policies rule authoring may
// write. "replace" was de-advertised in finding #2 (2026-07-03 remediation)
// — it wrote a contribution that materialized to a 0 limit — and removed from
// the add-rule dropdown and rejected server-side.
//
// Narrowed to additive-only on 2026-08-22 (maintainer decision, schema-hardening
// change, design D9): the additive/maximum selector confused operators, and
// mixing policies on one resource made limits depend on purchase order. This
// is authoring-only — the materializer, existing rows, and the DB column are
// untouched; rows already carrying "maximum" (or "replace") keep computing
// and render read-only in the rules table. Exploring what stacking policies
// are for, whether the rule form is the right home, and the eventual
// mixed-policy semantics is tracked as its own issue in status/issues.md
// rather than built now.
var allowedStackingPolicies = map[string]bool{
	"additive": true,
}

// CreateEntitlementSet handles POST /partials/operator/entitlement-sets
func (h *OperatorPartialsHandler) CreateEntitlementSet(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		h.renderEntitlementSetsPage(w, r, "", "Invalid request")
		return
	}

	name := r.FormValue("name")
	description := r.FormValue("description")

	errs := web.New()
	if name == "" {
		errs.Set("name", "Name is required.")
	}
	if errs.Any() {
		h.renderEntitlementSetsFormErrors(w, r, errs)
		return
	}

	_, err := h.EntitlementsQ.CreateEntitlementSet(r.Context(), entitlements.CreateEntitlementSetParams{
		Name:        name,
		Description: sql.NullString{String: description, Valid: description != ""},
		IsActive:    true,
	})
	if err != nil {
		if fe, ok := web.FieldErrorsFromDB(err, entitlementSetNameConstraints); ok {
			h.renderEntitlementSetsFormErrors(w, r, fe)
			return
		}
		h.Logger.Error("failed to create entitlement set", slog.Any("error", err))
		h.renderEntitlementSetsPage(w, r, "", "Failed to create the entitlement set. Details are in the server logs.")
		return
	}

	// Signal dependent tabs (Products, Grants) to re-fetch — they show entitlement set dropdowns
	h.renderEntitlementSetsPage(w, r, "Entitlement set created successfully.", "")
}

// UpdateEntitlementSet handles PUT /partials/operator/entitlement-sets/{setID}
func (h *OperatorPartialsHandler) UpdateEntitlementSet(w http.ResponseWriter, r *http.Request) {
	setID := r.PathValue("setID")
	if err := r.ParseForm(); err != nil {
		h.renderEntitlementSetEditPage(w, r, setID, "", "Invalid request")
		return
	}

	name := r.FormValue("name")
	description := r.FormValue("description")

	errs := web.New()
	if name == "" {
		errs.Set("name", "Name is required.")
	}
	if errs.Any() {
		h.renderEntitlementSetEditFormErrors(w, r, setID, errs)
		return
	}

	isActive := r.FormValue("is_active") == "true"

	_, err := h.EntitlementsQ.UpdateEntitlementSet(r.Context(), entitlements.UpdateEntitlementSetParams{
		SetID:       setID,
		Name:        name,
		Description: sql.NullString{String: description, Valid: description != ""},
		IsActive:    isActive,
	})
	if err != nil {
		if fe, ok := web.FieldErrorsFromDB(err, entitlementSetNameConstraints); ok {
			h.renderEntitlementSetEditFormErrors(w, r, setID, fe)
			return
		}
		h.Logger.Error("failed to update entitlement set", slog.Any("error", err))
		h.renderEntitlementSetEditPage(w, r, setID, "", "Failed to update the entitlement set. Details are in the server logs.")
		return
	}

	// Stay on the set's composite detail page (the boosted nav already set the
	// URL); re-render in place reflecting the saved changes.
	h.renderEntitlementSetDetailBody(w, r, setID, "Entitlement set updated successfully.", "")
}

// CreateEntitlementSetRule handles POST /partials/operator/entitlement-sets/{setID}/rules
func (h *OperatorPartialsHandler) CreateEntitlementSetRule(w http.ResponseWriter, r *http.Request) {
	setID := r.PathValue("setID")
	if err := r.ParseForm(); err != nil {
		h.renderEntitlementSetRulesPage(w, r, setID, "", "Invalid request")
		return
	}

	resourceKey := r.FormValue("resource_key")

	errs := web.New()
	if resourceKey == "" {
		errs.Set("resource_key", "Resource key is required.")
		h.renderEntitlementSetRulesFormErrors(w, r, setID, errs)
		return
	}

	// The rule type is derived from the key's kind, never from client input —
	// the schema CHECK makes a wrong-shape rule invalid, and deriving here
	// makes it unreachable (a stale form or crafted POST cannot choose).
	rk, err := h.EntitlementsQ.GetResourceKey(r.Context(), resourceKey)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			errs.Set("resource_key", "That resource key no longer exists. Refresh the page and choose another.")
			h.renderEntitlementSetRulesFormErrors(w, r, setID, errs)
			return
		}
		h.Logger.Error("failed to look up resource key", slog.Any("error", err))
		h.renderEntitlementSetRulesPage(w, r, setID, "", "Failed to create the rule. Details are in the server logs.")
		return
	}

	params := entitlements.CreateEntitlementSetRuleParams{
		SetID:       setID,
		ResourceKey: sql.NullString{String: resourceKey, Valid: true},
	}
	if rk.Kind == "boolean" {
		// chk_entitlement_set_rules_type requires NULL resource_value,
		// stacking_policy, and resource_per_unit on boolean rules (the
		// stacking column default 'additive' would violate it, so the
		// zero-valued Valid:false params are load-bearing). Numeric inputs a
		// stale form may still submit are ignored.
		params.RuleType = "boolean"
	} else {
		params.RuleType = "limit"
		resourceValueStr := r.FormValue("resource_value")
		resourcePerUnit := r.FormValue("resource_per_unit") == "true"

		// The form no longer renders a stacking-policy control (2026-08-22,
		// design D9): rule authoring is additive-only. A blank submission
		// (the normal case) defaults to "additive"; a non-empty value other
		// than "additive" — a smuggled "maximum" or de-advertised "replace"
		// from a stale tab or crafted POST — is rejected server-side and
		// nothing is written.
		stackingPolicy := r.FormValue("stacking_policy")
		if stackingPolicy == "" {
			stackingPolicy = "additive"
		} else if !allowedStackingPolicies[stackingPolicy] {
			errs.Set("stacking_policy", "Stacking policy must be additive.")
		}
		var resourceValue int64
		if resourceValueStr == "" {
			errs.Set("resource_value", "Resource value is required.")
		} else {
			v, err := strconv.ParseInt(resourceValueStr, 10, 64)
			if err != nil {
				errs.Set("resource_value", "Resource value must be an integer.")
			} else {
				resourceValue = v
			}
		}
		if errs.Any() {
			h.renderEntitlementSetRulesFormErrors(w, r, setID, errs)
			return
		}
		params.ResourceValue = sql.NullInt64{Int64: resourceValue, Valid: true}
		params.ResourcePerUnit = sql.NullBool{Bool: resourcePerUnit, Valid: true}
		params.StackingPolicy = sql.NullString{String: stackingPolicy, Valid: true}
	}

	_, err = h.EntitlementsQ.CreateEntitlementSetRule(r.Context(), params)
	if err != nil {
		if fe, ok := web.FieldErrorsFromDB(err, web.ConstraintMessages{
			"entitlement_set_rules_resource_key_fkey":      {Field: "resource_key", Message: "That resource key no longer exists. Refresh the page and choose another."},
			"chk_entitlement_set_rules_type":               {Field: "resource_value", Message: "These values do not form a valid rule for this resource key."},
			"uq_entitlement_set_rules_active_resource_key": {Field: "resource_key", Message: "This set already has a rule for that resource key. Delete the existing rule before adding another."},
		}); ok {
			h.renderEntitlementSetRulesFormErrors(w, r, setID, fe)
			return
		}
		h.Logger.Error("failed to create rule", slog.Any("error", err))
		h.renderEntitlementSetRulesPage(w, r, setID, "", "Failed to create the rule. Details are in the server logs.")
		return
	}

	h.renderEntitlementSetRulesPage(w, r, setID, "Rule added successfully.", "")
}

// GetEntitlementSetRuleFields handles GET /partials/operator/entitlement-sets/{setID}/rules/fields.
// The add-rule form's key select swaps this partial into #ruleFields on change,
// so the fields region always matches the selected key's kind.
func (h *OperatorPartialsHandler) GetEntitlementSetRuleFields(w http.ResponseWriter, r *http.Request) {
	h.Templates.Render(w, "operator_entitlement_set_rule_fields.html", h.ruleFieldsForKey(r, r.URL.Query().Get("resource_key"), nil))
}

// ruleFieldsForKey resolves the fields-region view state for a selected key.
// Empty or unknown keys yield the hint state (SelectedKind "").
func (h *OperatorPartialsHandler) ruleFieldsForKey(r *http.Request, resourceKey string, errs web.FieldErrors) RuleFieldsData {
	data := RuleFieldsData{SelectedKey: resourceKey, FieldErrors: errs}
	if resourceKey == "" {
		return data
	}
	rk, err := h.EntitlementsQ.GetResourceKey(r.Context(), resourceKey)
	if err != nil {
		if !errors.Is(err, sql.ErrNoRows) {
			h.Logger.Error("failed to look up resource key", slog.Any("error", err))
		}
		return data
	}
	data.SelectedKind = rk.Kind
	return data
}

// DeleteEntitlementSetRule handles DELETE /partials/operator/entitlement-sets/{setID}/rules/{ruleID}
func (h *OperatorPartialsHandler) DeleteEntitlementSetRule(w http.ResponseWriter, r *http.Request) {
	setID := r.PathValue("setID")
	ruleID := r.PathValue("ruleID")

	err := h.EntitlementsQ.DeleteEntitlementSetRule(r.Context(), ruleID)
	if err != nil {
		// The delete button has no form to attach 422 FieldErrors to —
		// surface translated constraint text through the banner shape.
		if fe, ok := web.FieldErrorsFromDB(err, nil); ok {
			h.renderEntitlementSetRulesPage(w, r, setID, "", fieldErrorsBanner(fe))
			return
		}
		h.Logger.Error("failed to delete rule", slog.Any("error", err))
		h.renderEntitlementSetRulesPage(w, r, setID, "", "Failed to delete the rule. Details are in the server logs.")
		return
	}

	h.renderEntitlementSetRulesPage(w, r, setID, "Rule deleted.", "")
}

// Rendering helpers

func (h *OperatorPartialsHandler) renderEntitlementSetsPage(w http.ResponseWriter, r *http.Request, success string, errMsg string) {
	fireSuccessToast(w, success)
	data := h.loadEntitlementSetsPageData(r, "", errMsg)
	h.Templates.Render(w, "operator_entitlement_sets.html", data)
}

// loadEntitlementSetsPageData hydrates the entitlement-sets listing. Shared
// by the legacy partial endpoint (renderEntitlementSetsPage) and the new MPA
// page handler (GetEntitlementSetsPage).
func (h *OperatorPartialsHandler) loadEntitlementSetsPageData(r *http.Request, success string, errMsg string) EntitlementSetsData {
	data := EntitlementSetsData{
		Success: success,
		Error:   errMsg,
		// Entitlement sets are never blocked; the empty state is always
		// actionable (ux-first-run 3.4). Set unconditionally, including on
		// the error-return path below, so a transient DB error never leaves
		// the empty-state block rendering with blank copy.
		Empty: EmptyStateParams{
			Headline:    "No entitlement sets yet.",
			Note:        "Rules feed into a set, and products consume it. Creating a set is the first step toward a sellable product.",
			ActionURL:   "#createEntitlementSetForm",
			ActionLabel: "Create Entitlement Set",
		},
	}
	// A stale-detail GET redirects here with ?flash=missing; surface it as the
	// page banner (finding #53) without clobbering an explicit mutation-guard
	// errMsg.
	if data.Error == "" && r.URL.Query().Get("flash") == "missing" {
		data.Error = "That entitlement set no longer exists — it may have been deleted."
	}

	// Finding #54: always hydrate the table and create form, even when a banner
	// is set, so an unrecognized error never wipes the whole management surface.
	sets, err := h.EntitlementsQ.ListEntitlementSets(r.Context())
	if err != nil {
		h.Logger.Error("failed to list entitlement sets", slog.Any("error", err))
		if data.Error == "" {
			data.Error = "Failed to load entitlement sets"
		}
		return data
	}

	data.EntitlementSets = make([]EntitlementSetViewModel, len(sets))
	for i, s := range sets {
		ruleCount := 0
		if rules, err := h.EntitlementsQ.GetActiveRulesBySetID(r.Context(), s.SetID); err == nil {
			ruleCount = len(rules)
		}
		desc := ""
		if s.Description.Valid {
			desc = s.Description.String
		}
		data.EntitlementSets[i] = EntitlementSetViewModel{
			SetID:       s.SetID,
			Name:        s.Name,
			Description: desc,
			IsActive:    s.IsActive,
			RuleCount:   ruleCount,
			CreatedAt:   s.CreatedAt.Format("Jan 2, 2006"),
		}
	}
	return data
}

// renderEntitlementSetsFormErrors re-renders the entitlement-sets page
// (the inline create-set form lives on it) with 422 + FieldErrors populated.
// Convention per docs/operator-ux-conventions.md §6+§8.
func (h *OperatorPartialsHandler) renderEntitlementSetsFormErrors(w http.ResponseWriter, r *http.Request, errs web.FieldErrors) {
	w.WriteHeader(http.StatusUnprocessableEntity)
	data := h.loadEntitlementSetsPageData(r, "", "")
	data.FieldErrors = errs
	h.Templates.Render(w, "operator_entitlement_sets.html", data)
}

// renderEntitlementSetRulesFormErrors re-renders the rules page (with its
// inline add-rule form) with 422 + FieldErrors populated. Convention per
// docs/operator-ux-conventions.md §6+§8.
//
// The header MUST be written before any body bytes, so the data loading
// is inlined here rather than calling renderEntitlementSetRulesPage (which
// would write the body before we could 422-stamp the header). The load
// logic mirrors renderEntitlementSetRulesPage's hydration steps.
func (h *OperatorPartialsHandler) renderEntitlementSetRulesFormErrors(w http.ResponseWriter, r *http.Request, setID string, errs web.FieldErrors) {
	w.WriteHeader(http.StatusUnprocessableEntity)
	edit, ok := h.loadEntitlementSetEditData(r, setID)
	if !ok {
		h.renderEntitlementSetsPage(w, r, "", "Entitlement set not found")
		return
	}
	rules := h.loadEntitlementSetRulesData(r, setID)
	rules.FieldErrors = errs
	// Restore the fields region to the submitted key's branch so value/stacking
	// errors render on the fields they belong to.
	rules.RuleFields = h.ruleFieldsForKey(r, r.FormValue("resource_key"), errs)
	h.Templates.Render(w, "operator_entitlement_set_detail.html", EntitlementSetDetailData{
		Edit:  edit,
		Rules: rules,
	})
}

// renderEntitlementSetEditFormErrors re-renders the edit form with 422 +
// FieldErrors populated. Convention per docs/operator-ux-conventions.md §6+§8.
func (h *OperatorPartialsHandler) renderEntitlementSetEditFormErrors(w http.ResponseWriter, r *http.Request, setID string, errs web.FieldErrors) {
	w.WriteHeader(http.StatusUnprocessableEntity)
	edit, ok := h.loadEntitlementSetEditData(r, setID)
	if !ok {
		h.renderEntitlementSetsPage(w, r, "", "Entitlement set not found")
		return
	}
	edit.FieldErrors = errs
	h.Templates.Render(w, "operator_entitlement_set_detail.html", EntitlementSetDetailData{
		Edit:  edit,
		Rules: h.loadEntitlementSetRulesData(r, setID),
	})
}

// loadEntitlementSetEditData hydrates the edit-form view model for one set.
// ok=false means the set does not exist.
func (h *OperatorPartialsHandler) loadEntitlementSetEditData(r *http.Request, setID string) (EntitlementSetEditData, bool) {
	data, found, err := h.loadEntitlementSetEditDataResult(r, setID)
	return data, found && err == nil
}

// loadEntitlementSetEditDataResult is loadEntitlementSetEditData with the
// not-found vs. transient-DB-error distinction preserved: found=false with
// err=nil means the set does not exist; err != nil means the load itself
// failed. The full-page GET (GetEntitlementSetDetailPage) uses this to redirect
// on the former and return a full-shell 500 on the latter, rather than
// conflating the two (finding #53).
func (h *OperatorPartialsHandler) loadEntitlementSetEditDataResult(r *http.Request, setID string) (EntitlementSetEditData, bool, error) {
	es, err := h.EntitlementsQ.GetEntitlementSetByID(r.Context(), setID)
	if errors.Is(err, sql.ErrNoRows) {
		return EntitlementSetEditData{}, false, nil
	}
	if err != nil {
		h.Logger.Error("failed to get entitlement set", slog.Any("error", err))
		return EntitlementSetEditData{}, false, err
	}

	desc := ""
	if es.Description.Valid {
		desc = es.Description.String
	}
	return EntitlementSetEditData{
		EntitlementSet: EntitlementSetViewModel{
			SetID:       es.SetID,
			Name:        es.Name,
			Description: desc,
			IsActive:    es.IsActive,
			CreatedAt:   es.CreatedAt.Format("Jan 2, 2006"),
		},
	}, true, nil
}

// GetEntitlementSetDetailPage handles GET /operator/entitlement-sets/{setID} —
// the addressable, bookmarkable per-set composite. Renders the operator.html
// shell with the edit form and rules manager co-located on one URL. Unknown
// setID degrades to the entitlement-sets browse page with an error.
func (h *OperatorPartialsHandler) GetEntitlementSetDetailPage(w http.ResponseWriter, r *http.Request) {
	setID := r.PathValue("setID")
	edit, found, err := h.loadEntitlementSetEditDataResult(r, setID)
	if err != nil {
		// Transient load failure — keep the operator inside the shell (nav, CSS)
		// with a 500 instead of mislabeling it "not found" (finding #53).
		errPage := h.buildOperatorPageData(r)
		errPage.IAPosition = "catalog:entitlement-sets"
		errPage.ActiveCapability = "entitlement-sets"
		errPage.BodyTemplate = "operator_entitlement_sets.html"
		errPage.BodyData = h.loadEntitlementSetsPageData(r, "", "Could not load this entitlement set right now. Please try again.")
		w.WriteHeader(http.StatusInternalServerError)
		h.Templates.Render(w, "operator.html", errPage)
		return
	}
	if !found {
		// Stale/unknown ID — normalize the URL back to the browse route and carry
		// a flash so the operator understands the bounce (finding #53).
		http.Redirect(w, r, "/operator/entitlement-sets?flash=missing", http.StatusSeeOther)
		return
	}

	page := h.buildOperatorPageData(r)
	page.IAPosition = "catalog:entitlement-sets:" + setID
	page.ActiveCapability = "entitlement-sets"
	page.BodyTemplate = "operator_entitlement_set_detail.html"
	page.BodyData = EntitlementSetDetailData{
		Edit:  edit,
		Rules: h.loadEntitlementSetRulesData(r, setID),
	}

	h.Templates.Render(w, "operator.html", page)
}

// renderEntitlementSetDetailBody re-renders the composite set detail body into
// #operator-body after an in-page mutation. The operator stays on
// /operator/entitlement-sets/{setID}; unknown setID degrades to the browse page.
func (h *OperatorPartialsHandler) renderEntitlementSetDetailBody(w http.ResponseWriter, r *http.Request, setID string, success string, errMsg string) {
	fireSuccessToast(w, success)
	edit, ok := h.loadEntitlementSetEditData(r, setID)
	if !ok {
		h.renderEntitlementSetsPage(w, r, "", "Entitlement set not found")
		return
	}
	// Finding #41: set only the composite-level Error so the alert renders once
	// at page top; setting edit.Error too stacked an identical banner inside the
	// Edit card, visually blaming the wrong form.
	h.Templates.Render(w, "operator_entitlement_set_detail.html", EntitlementSetDetailData{
		Edit:  edit,
		Rules: h.loadEntitlementSetRulesData(r, setID),
		Error: errMsg,
	})
}

// renderEntitlementSetEditPage re-renders the set composite in place. Retained as
// a thin alias so the mutation call sites (UpdateEntitlementSet) keep working;
// the edit form now lives on the composite detail page.
func (h *OperatorPartialsHandler) renderEntitlementSetEditPage(w http.ResponseWriter, r *http.Request, setID string, success string, errMsg string) {
	h.renderEntitlementSetDetailBody(w, r, setID, success, errMsg)
}

// renderEntitlementSetRulesPage re-renders the set composite in place. Retained
// as a thin alias so the rule mutation call sites (add/delete) keep working; the
// rules manager now lives on the composite detail page.
func (h *OperatorPartialsHandler) renderEntitlementSetRulesPage(w http.ResponseWriter, r *http.Request, setID string, success string, errMsg string) {
	h.renderEntitlementSetDetailBody(w, r, setID, success, errMsg)
}

// ruleResourceKeyIsLiveBacking reports whether resourceKey currently backs an
// entitlement some pool actively holds: a numeric contribution from a live
// (non-ended) provision, or a granted boolean key. It drives the Delete
// control's inline consequence copy (ux-honest-surfaces UX-10) — deleting a
// rule never re-materializes pools, so this is read-only and best-effort; a
// query failure renders as "not live-backing" rather than blocking the page.
func (h *OperatorPartialsHandler) ruleResourceKeyIsLiveBacking(ctx context.Context, ruleType, resourceKey string) bool {
	if resourceKey == "" || h.Database == nil {
		return false
	}
	var live bool
	var err error
	if ruleType == "boolean" {
		err = h.Database.QueryRowContext(ctx,
			`SELECT EXISTS (SELECT 1 FROM core.boolean_entitlements WHERE resource_key = $1 AND granted = TRUE)`,
			resourceKey,
		).Scan(&live)
	} else {
		// Contributions are recreated from each pool's currently active
		// provisions on every materialization (materialize.go) and deleted
		// outright once a provision ends, so a surviving row means some pool's
		// materialized limit is presently backed by this resource key.
		err = h.Database.QueryRowContext(ctx,
			`SELECT EXISTS (
				SELECT 1 FROM core.numeric_entitlement_contributions c
				JOIN core.numeric_entitlements ne ON ne.entitlement_id = c.entitlement_id
				WHERE ne.resource_key = $1
			)`,
			resourceKey,
		).Scan(&live)
	}
	if err != nil {
		h.Logger.Error("failed to check live-backing for resource key", slog.Any("error", err), slog.String("resource_key", resourceKey))
		return false
	}
	return live
}

// loadEntitlementSetRulesData hydrates the rules-manager view model for one set:
// the active rules and the resource keys available for the add-rule dropdown.
// Best-effort — a query failure yields a partial result rather than aborting,
// since this feeds the composite detail page where the set's existence is
// already established.
func (h *OperatorPartialsHandler) loadEntitlementSetRulesData(r *http.Request, setID string) EntitlementSetRulesData {
	data := EntitlementSetRulesData{}
	if es, err := h.EntitlementsQ.GetEntitlementSetByID(r.Context(), setID); err == nil {
		desc := ""
		if es.Description.Valid {
			desc = es.Description.String
		}
		data.EntitlementSet = EntitlementSetViewModel{
			SetID:       es.SetID,
			Name:        es.Name,
			Description: desc,
			IsActive:    es.IsActive,
		}
	}

	rules, err := h.EntitlementsQ.GetActiveRulesBySetID(r.Context(), setID)
	if err != nil {
		h.Logger.Error("failed to list rules", slog.Any("error", err))
	} else {
		data.Rules = make([]RuleViewModel, len(rules))
		for i, rule := range rules {
			rk := ""
			if rule.ResourceKey.Valid {
				rk = rule.ResourceKey.String
			}
			var rv int64
			if rule.ResourceValue.Valid {
				rv = rule.ResourceValue.Int64
			}
			rpu := false
			if rule.ResourcePerUnit.Valid {
				rpu = rule.ResourcePerUnit.Bool
			}
			sp := ""
			if rule.StackingPolicy.Valid {
				sp = rule.StackingPolicy.String
			}
			data.Rules[i] = RuleViewModel{
				RuleID:          rule.RuleID,
				RuleType:        rule.RuleType,
				ResourceKey:     rk,
				ResourceValue:   rv,
				ResourcePerUnit: rpu,
				StackingPolicy:  sp,
				IsActive:        rule.IsActive,
				IsLiveBacking:   h.ruleResourceKeyIsLiveBacking(r.Context(), rule.RuleType, rk),
			}
		}
	}

	// Load resource keys for the add-rule dropdown, excluding keys that already
	// have an active rule on this set (finding #21). One active rule per
	// (set_id, resource_key) is enforced by a unique index; hiding ruled keys
	// keeps the dropdown from offering a choice that can only 422.
	ruledKeys := make(map[string]bool, len(data.Rules))
	for _, rule := range data.Rules {
		if rule.ResourceKey != "" {
			ruledKeys[rule.ResourceKey] = true
		}
	}
	resourceKeys, err := h.EntitlementsQ.ListResourceKeys(r.Context())
	if err != nil {
		h.Logger.Error("failed to list resource keys", slog.Any("error", err))
	} else {
		data.ResourceKeys = make([]ResourceKeyOption, 0, len(resourceKeys))
		for _, rk := range resourceKeys {
			if ruledKeys[rk.ResourceKey] {
				continue
			}
			data.ResourceKeys = append(data.ResourceKeys, ResourceKeyOption{
				ResourceKey: rk.ResourceKey,
				DisplayName: rk.DisplayName,
			})
		}
	}

	return data
}