import {
  filterSearchableSelectOptions,
  unavailableReferenceOption,
  type ApiSettings,
  type ConfigurationReferenceSelectorsUiCapability,
  type ReferenceOption,
  type ReferenceOptionProvider
} from "@govoplan/core-webui";
import {
  fetchConfigurationChanges,
  fetchTenants,
  type ConfigurationChangeRequest
} from "../../api/admin";

export const configurationReferenceSelectors: ConfigurationReferenceSelectorsUiCapability = {
  tenantProvider: createTenantReferenceProvider,
  changeRequestProvider: createChangeRequestReferenceProvider
};

export function createTenantReferenceProvider(
  settings: ApiSettings
): ReferenceOptionProvider {
  async function catalogue(signal: AbortSignal): Promise<ReferenceOption[]> {
    const tenants = await fetchTenants(settings);
    if (signal.aborted) throw abortError();
    return tenants.map((tenant) => ({
      value: tenant.id,
      label: tenant.name || tenant.slug || tenant.id,
      description: [
        tenant.slug,
        tenant.is_active ? null : "Inactive",
        tenant.id
      ].filter(Boolean).join(" · "),
      kind: "tenant",
      availability: tenant.is_active ? "available" : "inactive",
      disabled: !tenant.is_active,
      sourceModule: "tenancy",
      provenance: {
        tenantId: tenant.id,
        active: tenant.is_active
      }
    }));
  }
  return {
    async search(query, context) {
      const options = await catalogue(context.signal);
      return retainSelected(
        filterSearchableSelectOptions(options, query, context.limit),
        options,
        context.selectedValues
      );
    },
    async resolve(values, context) {
      const options = await catalogue(context.signal);
      const byValue = new Map(options.map((option) => [option.value, option]));
      return values.map(
        (value) =>
          byValue.get(value)
          ?? unavailableReferenceOption(value, "Unavailable tenant")
      );
    }
  };
}

export function createChangeRequestReferenceProvider(
  settings: ApiSettings,
  {
    purpose,
    tenantId
  }: {
    purpose: string;
    tenantId?: string | null;
  }
): ReferenceOptionProvider {
  async function catalogue(signal: AbortSignal): Promise<{
    eligible: ReferenceOption[];
    all: ReferenceOption[];
  }> {
    const response = await fetchConfigurationChanges(settings);
    if (signal.aborted) throw abortError();
    const matching = response.requests.filter(
      (request) =>
        request.key === purpose
        && requestTargetsTenant(request, tenantId)
    );
    const all = matching.map(changeRequestOption);
    return {
      eligible: all.filter((option) => !option.disabled),
      all
    };
  }
  return {
    async search(query, context) {
      const options = await catalogue(context.signal);
      return retainSelected(
        filterSearchableSelectOptions(
          options.eligible,
          query,
          context.limit
        ),
        options.all,
        context.selectedValues
      );
    },
    async resolve(values, context) {
      const options = await catalogue(context.signal);
      const byValue = new Map(
        options.all.map((option) => [option.value, option])
      );
      return values.map(
        (value) =>
          byValue.get(value)
          ?? unavailableReferenceOption(
            value,
            "Unavailable configuration request"
          )
      );
    }
  };
}

function changeRequestOption(
  request: ConfigurationChangeRequest
): ReferenceOption {
  const closed = request.status === "applied" || request.status === "rejected";
  const eligible = request.status === "approved" && request.dry_run;
  return {
    value: request.id,
    label: request.label || request.key,
    description: [
      request.status.split("_").join(" "),
      request.dry_run ? null : "dry run not recorded",
      formatTimestamp(request.requested_at),
      `requested by ${request.requested_by}`,
      request.id
    ].filter(Boolean).join(" · "),
    searchText: `${request.id} ${request.requested_by} ${request.status}`,
    kind: "configuration_change_request",
    availability: closed
      ? "unavailable"
      : eligible
        ? "available"
        : "inactive",
    disabled: !eligible,
    sourceModule: "admin",
    provenance: {
      purpose: request.key,
      target: request.target ?? {},
      requestedBy: request.requested_by,
      requestedAt: request.requested_at,
      status: request.status,
      dryRunRecorded: request.dry_run
    }
  };
}

function requestTargetsTenant(
  request: ConfigurationChangeRequest,
  tenantId?: string | null
): boolean {
  if (!tenantId) return true;
  const targetTenant = request.target?.tenant_id;
  return !targetTenant || String(targetTenant) === tenantId;
}

function retainSelected(
  matches: readonly ReferenceOption[],
  catalogue: readonly ReferenceOption[],
  selectedValues: readonly string[]
): ReferenceOption[] {
  const result = [...matches];
  const returned = new Set(result.map((option) => option.value));
  const byValue = new Map(catalogue.map((option) => [option.value, option]));
  for (const value of selectedValues) {
    if (returned.has(value)) continue;
    result.push(
      byValue.get(value)
      ?? unavailableReferenceOption(value)
    );
  }
  return result;
}

function formatTimestamp(value: string): string {
  const date = new Date(value);
  return Number.isNaN(date.getTime()) ? value : date.toLocaleString();
}

function abortError(): DOMException {
  return new DOMException("The operation was aborted.", "AbortError");
}