import crypto from "node:crypto";
import { and, desc, eq } from "drizzle-orm";
import { ProjectRevisionConflictError } from "../../domain/errors/project-revision-conflict.error.js";
import { ProjectSnapshotNameConflictError } from "../../domain/errors/project-snapshot-name-conflict.error.js";
import { createProjectStateRestoreCommand } from "../../domain/models/project-state-restore-command.model.js";
import {
  distributionBoardProjectStateSnapshotSchemaVersion,
  deserializeProjectStateSnapshot,
  legacyProjectStateSnapshotSchemaVersion,
  previousProjectStateSnapshotSchemaVersion,
  projectStateSnapshotSchemaVersion,
  supplyTypesProjectStateSnapshotSchemaVersion,
} from "../../domain/models/project-state-snapshot.model.js";
import type {
  CreateNamedProjectSnapshotInput,
  PreparedProjectSnapshotRestore,
  ProjectSnapshotMetadata,
  ProjectSnapshotStore,
} from "../../domain/ports/project-snapshot.store.js";
import type { AppDatabase } from "../database-context.js";
import { projectSnapshots } from "../schema/project-snapshots.js";
import { projects } from "../schema/projects.js";
import {
  hashProjectStatePayload,
  readProjectStateSnapshot,
} from "./project-state-snapshot.persistence.js";

export class ProjectSnapshotRepository implements ProjectSnapshotStore {
  constructor(private readonly database: AppDatabase) {}

  createNamed(
    input: CreateNamedProjectSnapshotInput
  ): ProjectSnapshotMetadata | null {
    validateCreateInput(input);
    const snapshotName = input.name.trim();
    const snapshotDescription =
      input.description?.trim() || null;
    return this.database.transaction((tx) => {
      const current = readProjectStateSnapshot(tx, input.projectId);
      if (!current) {
        return null;
      }
      if (current.currentRevision !== input.expectedRevision) {
        throw new ProjectRevisionConflictError(
          input.projectId,
          input.expectedRevision,
          current.currentRevision
        );
      }
      const existing = tx
        .select({ id: projectSnapshots.id })
        .from(projectSnapshots)
        .where(
          and(
            eq(projectSnapshots.projectId, input.projectId),
            eq(projectSnapshots.name, snapshotName)
          )
        )
        .get();
      if (existing) {
        throw new ProjectSnapshotNameConflictError(
          input.projectId,
          snapshotName
        );
      }

      const metadata: ProjectSnapshotMetadata = {
        id: crypto.randomUUID(),
        projectId: input.projectId,
        sourceRevision: current.currentRevision,
        schemaVersion: projectStateSnapshotSchemaVersion,
        kind: "named",
        name: snapshotName,
        description: snapshotDescription,
        payloadSha256: current.payloadSha256,
        createdAtIso: new Date().toISOString(),
        createdByActorId: input.actorId ?? null,
      };
      tx.insert(projectSnapshots)
        .values({
          ...metadata,
          payloadJson: current.payloadJson,
        })
        .run();
      return metadata;
    });
  }

  listByProject(projectId: string): ProjectSnapshotMetadata[] | null {
    const project = this.database
      .select({ id: projects.id })
      .from(projects)
      .where(eq(projects.id, projectId))
      .get();
    if (!project) {
      return null;
    }
    return this.database
      .select({
        id: projectSnapshots.id,
        projectId: projectSnapshots.projectId,
        sourceRevision: projectSnapshots.sourceRevision,
        schemaVersion: projectSnapshots.schemaVersion,
        kind: projectSnapshots.kind,
        name: projectSnapshots.name,
        description: projectSnapshots.description,
        payloadSha256: projectSnapshots.payloadSha256,
        createdAtIso: projectSnapshots.createdAtIso,
        createdByActorId: projectSnapshots.createdByActorId,
      })
      .from(projectSnapshots)
      .where(eq(projectSnapshots.projectId, projectId))
      .orderBy(
        desc(projectSnapshots.createdAtIso),
        desc(projectSnapshots.id)
      )
      .all();
  }

  prepareRestore(
    projectId: string,
    snapshotId: string
  ): PreparedProjectSnapshotRestore | null {
    const current = readProjectStateSnapshot(this.database, projectId);
    if (!current) {
      return null;
    }
    const stored = this.database
      .select()
      .from(projectSnapshots)
      .where(
        and(
          eq(projectSnapshots.id, snapshotId),
          eq(projectSnapshots.projectId, projectId)
        )
      )
      .get();
    if (!stored) {
      return null;
    }
    const actualChecksum = hashProjectStatePayload(stored.payloadJson);
    if (actualChecksum !== stored.payloadSha256) {
      throw new Error("Project snapshot checksum verification failed.");
    }
    if (
      stored.schemaVersion !== legacyProjectStateSnapshotSchemaVersion &&
      stored.schemaVersion !== previousProjectStateSnapshotSchemaVersion &&
      stored.schemaVersion !==
        distributionBoardProjectStateSnapshotSchemaVersion &&
      stored.schemaVersion !==
        supplyTypesProjectStateSnapshotSchemaVersion &&
      stored.schemaVersion !== projectStateSnapshotSchemaVersion
    ) {
      throw new Error("Project snapshot schema version is not supported.");
    }
    const targetState = deserializeProjectStateSnapshot(stored.payloadJson);
    return {
      snapshot: {
        id: stored.id,
        projectId: stored.projectId,
        sourceRevision: stored.sourceRevision,
        schemaVersion: stored.schemaVersion,
        kind: stored.kind,
        name: stored.name,
        description: stored.description,
        payloadSha256: stored.payloadSha256,
        createdAtIso: stored.createdAtIso,
        createdByActorId: stored.createdByActorId,
      },
      command: createProjectStateRestoreCommand(
        current.payloadSha256,
        targetState
      ),
    };
  }
}

function validateCreateInput(input: CreateNamedProjectSnapshotInput) {
  if (
    !Number.isSafeInteger(input.expectedRevision) ||
    input.expectedRevision < 0
  ) {
    throw new Error(
      "Expected project revision must be a non-negative integer."
    );
  }
  if (!input.name.trim()) {
    throw new Error("Project snapshot name is required.");
  }
  if (input.name.trim().length > 100) {
    throw new Error(
      "Project snapshot name must not exceed 100 characters."
    );
  }
  if (
    input.description !== undefined &&
    input.description.trim().length > 500
  ) {
    throw new Error(
      "Project snapshot description must not exceed 500 characters."
    );
  }
}