import crypto from "node:crypto";
import { and, desc, eq, inArray } from "drizzle-orm";
import {
  automaticProjectSnapshotIntervalRevisions,
  automaticProjectSnapshotRetentionCount,
  shouldCaptureAutomaticProjectSnapshot,
} from "../../domain/models/project-snapshot-policy.model.js";
import { projectStateSnapshotSchemaVersion } from "../../domain/models/project-state-snapshot.model.js";
import type { ProjectSnapshotMetadata } from "../../domain/ports/project-snapshot.store.js";
import type { AppDatabase } from "../database-context.js";
import { projectSnapshots } from "../schema/project-snapshots.js";
import { readProjectStateSnapshot } from "./project-state-snapshot.persistence.js";

interface CaptureAutomaticProjectSnapshotInput {
  projectId: string;
  currentRevision: number;
  createdAtIso: string;
  actorId?: string;
}

export function captureAutomaticProjectSnapshot(
  database: AppDatabase,
  input: CaptureAutomaticProjectSnapshotInput
): ProjectSnapshotMetadata | null {
  const latest = database
    .select({ sourceRevision: projectSnapshots.sourceRevision })
    .from(projectSnapshots)
    .where(
      and(
        eq(projectSnapshots.projectId, input.projectId),
        eq(projectSnapshots.kind, "automatic")
      )
    )
    .orderBy(desc(projectSnapshots.sourceRevision))
    .get();
  if (
    !shouldCaptureAutomaticProjectSnapshot(
      input.currentRevision,
      latest?.sourceRevision ?? null
    )
  ) {
    return null;
  }

  const current = readProjectStateSnapshot(database, input.projectId);
  if (!current || current.currentRevision !== input.currentRevision) {
    throw new Error(
      "Automatic snapshot state does not match the appended revision."
    );
  }

  const id = crypto.randomUUID();
  const preferredName = `Automatisch · Revision ${input.currentRevision}`;
  const conflictingName = database
    .select({ id: projectSnapshots.id })
    .from(projectSnapshots)
    .where(
      and(
        eq(projectSnapshots.projectId, input.projectId),
        eq(projectSnapshots.name, preferredName)
      )
    )
    .get();
  const metadata: ProjectSnapshotMetadata = {
    id,
    projectId: input.projectId,
    sourceRevision: input.currentRevision,
    schemaVersion: projectStateSnapshotSchemaVersion,
    kind: "automatic",
    name: conflictingName
      ? `${preferredName} · ${id}`
      : preferredName,
    description: `Automatischer Sicherungspunkt nach jeweils ${automaticProjectSnapshotIntervalRevisions} Projektänderungen.`,
    payloadSha256: current.payloadSha256,
    createdAtIso: input.createdAtIso,
    createdByActorId: input.actorId ?? null,
  };
  database
    .insert(projectSnapshots)
    .values({
      ...metadata,
      payloadJson: current.payloadJson,
    })
    .run();

  const automaticSnapshots = database
    .select({ id: projectSnapshots.id })
    .from(projectSnapshots)
    .where(
      and(
        eq(projectSnapshots.projectId, input.projectId),
        eq(projectSnapshots.kind, "automatic")
      )
    )
    .orderBy(
      desc(projectSnapshots.sourceRevision),
      desc(projectSnapshots.createdAtIso),
      desc(projectSnapshots.id)
    )
    .all();
  const expiredIds = automaticSnapshots
    .slice(automaticProjectSnapshotRetentionCount)
    .map((snapshot) => snapshot.id);
  if (expiredIds.length) {
    database
      .delete(projectSnapshots)
      .where(inArray(projectSnapshots.id, expiredIds))
      .run();
  }
  return metadata;
}