import { createHash } from "node:crypto";
import { mkdir, mkdtemp, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import path from "node:path";
import { afterEach, describe, expect, it } from "vitest";
import {
  CORE_MIGRATION_SOURCE_ID,
  discoverAllMigrations,
  discoverCoreMigrations,
} from "../src/migrations/index.js";
import { ModuleMigrationDiscoveryError } from "../src/modules/index.js";

const originSnapshotId = "00000000-0000-0000-0000-000000000000";
const temporaryDirectories: string[] = [];

afterEach(async () => {
  await Promise.all(
    temporaryDirectories
      .splice(0)
      .map((directory) => rm(directory, { force: true, recursive: true })),
  );
});

async function createTemporaryDirectory(prefix: string): Promise<string> {
  const directory = await mkdtemp(path.join(tmpdir(), prefix));
  temporaryDirectories.push(directory);
  return directory;
}

/** Writes a single-migration Drizzle directory (journal + snapshot + policy + SQL). */
async function writeMigrationsDirectory(
  migrationsDirectory: string,
  moduleId: string,
  tag: string,
  sql: string,
): Promise<string> {
  await mkdir(path.join(migrationsDirectory, "meta"), { recursive: true });
  await Promise.all([
    writeFile(
      path.join(migrationsDirectory, "meta/_journal.json"),
      JSON.stringify({
        version: "7",
        dialect: "postgresql",
        entries: [{ idx: 0, version: "7", when: 1_700_000_000_000, tag, breakpoints: true }],
      }),
    ),
    writeFile(
      path.join(migrationsDirectory, "meta/_ekklesia.json"),
      JSON.stringify({
        version: 1,
        moduleId,
        entries: [{ tag, destructive: { mode: "none" } }],
      }),
    ),
    writeFile(
      path.join(migrationsDirectory, "meta/0000_snapshot.json"),
      JSON.stringify({
        version: "7",
        dialect: "postgresql",
        id: "10000000-0000-4000-8000-000000000001",
        prevId: originSnapshotId,
      }),
    ),
    writeFile(path.join(migrationsDirectory, `${tag}.sql`), sql),
  ]);
  return sql;
}

async function createModule(
  modulesDirectory: string,
  id: string,
  options: { readonly dependsOn?: readonly string[] } = {},
): Promise<void> {
  const moduleDirectory = path.join(modulesDirectory, id);
  const migrationsDirectory = path.join(moduleDirectory, "drizzle");
  await mkdir(path.join(moduleDirectory, "dist/server"), { recursive: true });
  const requiredDependencies = Object.fromEntries(
    (options.dependsOn ?? []).map((dependencyId) => [dependencyId, "^0.1.0"]),
  );

  await Promise.all([
    writeFile(
      path.join(moduleDirectory, "package.json"),
      JSON.stringify({
        name: `@test/module-${id}`,
        version: "0.1.0",
        type: "module",
        ekklesia: { layer: "module" },
      }),
    ),
    writeFile(
      path.join(moduleDirectory, "ekklesia.module.json"),
      JSON.stringify({
        manifestVersion: 2,
        id,
        name: `${id} module`,
        version: "0.1.0",
        compatibility: { platform: "^0.1.0", moduleSdk: "^0.1.0" },
        dependencies: {
          modules: { required: requiredDependencies, optional: {} },
          capabilities: { required: {}, optional: {} },
        },
        capabilities: [],
        permissions: [],
        entrypoints: { server: "./dist/server/index.js", migrations: "./drizzle" },
      }),
    ),
    writeFile(
      path.join(moduleDirectory, "dist/server/index.js"),
      `export default { id: ${JSON.stringify(id)}, version: "0.1.0" };`,
    ),
  ]);

  await writeMigrationsDirectory(
    migrationsDirectory,
    id,
    "0000_initial",
    `CREATE TABLE "${id.replaceAll("-", "_")}_records" ("id" integer);\n`,
  );
}

function sha256(contents: string): string {
  return createHash("sha256").update(contents).digest("hex");
}

describe("Core-owned migration discovery", () => {
  it("discovers Core's own migrations with the reserved core identity and an exact checksum", async () => {
    const coreMigrationsDirectory = await createTemporaryDirectory("ekklesia-core-migrations-");
    const sql = await writeMigrationsDirectory(
      coreMigrationsDirectory,
      "core",
      "0000_identity_core_tables",
      'CREATE TABLE "ekklesia_core_user" ("id" text PRIMARY KEY);\n',
    );

    const migrations = await discoverCoreMigrations({ coreMigrationsDirectory });

    expect(CORE_MIGRATION_SOURCE_ID).toBe("core");
    expect(migrations).toHaveLength(1);
    expect(migrations[0]).toMatchObject({
      approvalRequired: false,
      checksum: sha256(sql),
      identity: "core:0000_identity_core_tables",
      index: 0,
      moduleId: "core",
      tag: "0000_identity_core_tables",
    });
  });

  it("is deterministic across repeated discovery calls", async () => {
    const coreMigrationsDirectory = await createTemporaryDirectory("ekklesia-core-migrations-");
    await writeMigrationsDirectory(
      coreMigrationsDirectory,
      "core",
      "0000_identity_core_tables",
      'CREATE TABLE "ekklesia_core_user" ("id" text PRIMARY KEY);\n',
    );

    const first = await discoverCoreMigrations({ coreMigrationsDirectory });
    const second = await discoverCoreMigrations({ coreMigrationsDirectory });

    expect(first).toEqual(second);
  });

  it("orders Core migrations before every module migration while preserving dependency-first module order", async () => {
    const modulesDirectory = await createTemporaryDirectory("ekklesia-modules-");
    const coreMigrationsDirectory = await createTemporaryDirectory("ekklesia-core-migrations-");
    await writeMigrationsDirectory(
      coreMigrationsDirectory,
      "core",
      "0000_identity_core_tables",
      'CREATE TABLE "ekklesia_core_user" ("id" text PRIMARY KEY);\n',
    );
    // "calendar" depends on "people"; created on disk in the opposite order so only the
    // dependency graph (not directory order) can explain the resulting sequence.
    await createModule(modulesDirectory, "calendar", { dependsOn: ["people"] });
    await createModule(modulesDirectory, "people");

    const aggregate = await discoverAllMigrations({
      coreMigrationsDirectory,
      moduleDiscovery: { moduleSdkVersion: "0.1.0", modulesDirectory, platformVersion: "0.1.0" },
    });

    expect(aggregate.modules.map((module) => module.moduleId)).toEqual([
      "core",
      "people",
      "calendar",
    ]);
    expect(aggregate.migrations.map((migration) => migration.identity)).toEqual([
      "core:0000_identity_core_tables",
      "people:0000_initial",
      "calendar:0000_initial",
    ]);
  });

  it("rejects an installed module that reuses the reserved core migration identity", async () => {
    const modulesDirectory = await createTemporaryDirectory("ekklesia-modules-");
    const coreMigrationsDirectory = await createTemporaryDirectory("ekklesia-core-migrations-");
    await writeMigrationsDirectory(
      coreMigrationsDirectory,
      "core",
      "0000_identity_core_tables",
      'CREATE TABLE "ekklesia_core_user" ("id" text PRIMARY KEY);\n',
    );
    await createModule(modulesDirectory, "core");

    let captured: unknown;
    try {
      await discoverAllMigrations({
        coreMigrationsDirectory,
        moduleDiscovery: { moduleSdkVersion: "0.1.0", modulesDirectory, platformVersion: "0.1.0" },
      });
    } catch (error) {
      captured = error;
    }

    expect(captured).toBeInstanceOf(ModuleMigrationDiscoveryError);
    expect((captured as ModuleMigrationDiscoveryError).issues).toEqual([
      expect.objectContaining({ code: "MODULE_MIGRATION_ID_DUPLICATE", moduleId: "core" }),
    ]);
  });

  it("keeps a fresh, module-free repository honestly reporting only Core's migration", async () => {
    const modulesDirectory = await createTemporaryDirectory("ekklesia-modules-");
    const coreMigrationsDirectory = await createTemporaryDirectory("ekklesia-core-migrations-");
    await writeMigrationsDirectory(
      coreMigrationsDirectory,
      "core",
      "0000_identity_core_tables",
      'CREATE TABLE "ekklesia_core_user" ("id" text PRIMARY KEY);\n',
    );

    const aggregate = await discoverAllMigrations({
      coreMigrationsDirectory,
      moduleDiscovery: { moduleSdkVersion: "0.1.0", modulesDirectory, platformVersion: "0.1.0" },
    });

    expect(aggregate.discoveredModules).toEqual([]);
    expect(aggregate.modules).toHaveLength(1);
    expect(aggregate.modules[0]?.moduleId).toBe("core");
    expect(aggregate.migrations).toHaveLength(1);
  });
});