import { asc } from "drizzle-orm";
import { type ModuleEnablementRecord, moduleIdSchema } from "@ekklesia/contracts";
import { drizzle, type NodePgDatabase } from "drizzle-orm/node-postgres";
import type { Pool } from "pg";
import { createValidatedPostgresPool, type PostgresPoolOptions } from "../database/index.js";
import type { ModuleLifecycleConfiguration } from "./lifecycle.js";
import { ekklesiaCoreModuleState, moduleLifecycleSchema } from "./lifecycle-schema.js";

export type ModuleLifecycleDrizzleDatabase = NodePgDatabase<typeof moduleLifecycleSchema>;

/**
 * A typed Drizzle view over an externally owned pool, exactly like `createDashboardDrizzleView` and
 * `createAuthorizationDrizzleView`: it never constructs, registers an error listener on, or closes
 * a pool. The caller owns the pool once, however many typed views it creates over it.
 */
export function createModuleLifecycleView(pool: Pool): ModuleLifecycleDrizzleDatabase {
  return drizzle(pool, { schema: moduleLifecycleSchema });
}

export interface ModuleLifecycleDatabaseHandle {
  readonly close: () => Promise<void>;
  readonly db: ModuleLifecycleDrizzleDatabase;
}

/**
 * A self-contained handle for a caller that needs *only* this domain and owns the connection for
 * the length of one command — Doctor's read-only lifecycle check and the enable/disable CLI. It
 * composes the shared, already-validated pool factory rather than repeating a fourth copy of
 * connection-string and timeout validation. `apps/api`, which shares one physical pool across every
 * domain, uses `createModuleLifecycleView` instead.
 */
export function createModuleLifecycleDatabase(
  connectionString: string,
  options: PostgresPoolOptions = {},
): ModuleLifecycleDatabaseHandle {
  const { close, pool } = createValidatedPostgresPool(connectionString, options);
  return Object.freeze({ close, db: createModuleLifecycleView(pool) });
}

export type ModuleLifecycleStoreErrorCode =
  | "MODULE_LIFECYCLE_MODULE_ID_INVALID"
  | "MODULE_LIFECYCLE_READ_FAILED"
  | "MODULE_LIFECYCLE_WRITE_FAILED";

const storeErrorMessages: Readonly<Record<ModuleLifecycleStoreErrorCode, string>> = Object.freeze({
  MODULE_LIFECYCLE_MODULE_ID_INVALID: "A module identifier is invalid.",
  MODULE_LIFECYCLE_READ_FAILED: "The module lifecycle configuration could not be read.",
  MODULE_LIFECYCLE_WRITE_FAILED: "The module lifecycle configuration could not be saved.",
});

/** Never carries the underlying database error, SQL text, host, connection string, or stack —
 * matching `AuthorizationStoreError` and `DashboardStoreError` exactly. */
export class ModuleLifecycleStoreError extends Error {
  readonly code: ModuleLifecycleStoreErrorCode;

  constructor(code: ModuleLifecycleStoreErrorCode) {
    super(storeErrorMessages[code]);
    this.name = "ModuleLifecycleStoreError";
    this.code = code;
    this.stack = `${this.name}: ${this.message}`;
    Object.freeze(this);
  }
}

export interface SetModuleEnabledInput {
  readonly moduleId: string;
  readonly enabled: boolean;
}

export interface ModuleLifecycleStore {
  /** The whole stored configuration, in deterministic module-id order. Small by nature — at most one
   * row per module ever decided about — so it is read whole rather than paginated. */
  readConfiguration(): Promise<ModuleLifecycleConfiguration>;
  /** Records one explicit decision, creating or replacing it. Idempotent: the same input twice
   * leaves the same single row. Writing configuration never starts, stops, loads, or unloads
   * anything — the running process is untouched until it is restarted. */
  setEnabled(input: SetModuleEnabledInput): Promise<ModuleEnablementRecord>;
}

function assertValidModuleId(value: string): void {
  if (!moduleIdSchema.safeParse(value).success) {
    throw new ModuleLifecycleStoreError("MODULE_LIFECYCLE_MODULE_ID_INVALID");
  }
}

function rethrowAsStoreError(error: unknown, code: ModuleLifecycleStoreErrorCode): never {
  if (error instanceof ModuleLifecycleStoreError) {
    throw error;
  }
  throw new ModuleLifecycleStoreError(code);
}

/**
 * Core's persistence for which installed modules are enabled.
 *
 * Validation lives here rather than only at an HTTP boundary, so the invariant holds for every
 * caller — the API, the CLI, and any future one: an identifier is checked against
 * `moduleIdSchema`, the platform's one module-identifier grammar, rather than a second grammar
 * invented here.
 *
 * Nothing in this file reads a manifest, imports module code, resolves a dependency, or decides
 * whether a module may start. It stores a decision; `resolveModuleEligibility` interprets it. That
 * separation is what keeps enablement host-owned configuration instead of something a module could
 * ever influence.
 */
export function createModuleLifecycleStore(
  db: ModuleLifecycleDrizzleDatabase,
): ModuleLifecycleStore {
  return Object.freeze({
    async readConfiguration(): Promise<ModuleLifecycleConfiguration> {
      try {
        const rows = await db
          .select({
            enabled: ekklesiaCoreModuleState.enabled,
            moduleId: ekklesiaCoreModuleState.moduleId,
          })
          .from(ekklesiaCoreModuleState)
          .orderBy(asc(ekklesiaCoreModuleState.moduleId));
        return Object.freeze({
          modules: Object.freeze(rows.map((row) => Object.freeze({ ...row }))),
        });
      } catch (error) {
        rethrowAsStoreError(error, "MODULE_LIFECYCLE_READ_FAILED");
      }
    },

    async setEnabled(input: SetModuleEnabledInput): Promise<ModuleEnablementRecord> {
      assertValidModuleId(input.moduleId);
      try {
        const [row] = await db
          .insert(ekklesiaCoreModuleState)
          .values({ enabled: input.enabled, moduleId: input.moduleId })
          .onConflictDoUpdate({
            set: { enabled: input.enabled, updatedAt: new Date() },
            target: ekklesiaCoreModuleState.moduleId,
          })
          .returning({
            enabled: ekklesiaCoreModuleState.enabled,
            moduleId: ekklesiaCoreModuleState.moduleId,
          });
        if (!row) {
          throw new ModuleLifecycleStoreError("MODULE_LIFECYCLE_WRITE_FAILED");
        }
        return Object.freeze(row);
      } catch (error) {
        rethrowAsStoreError(error, "MODULE_LIFECYCLE_WRITE_FAILED");
      }
    },
  });
}