mod.ts

import type { Database } from "@db/sqlite";
import type * as zen from "@dldc/zendb";

export interface TDbDatabase {
  exec<Op extends zen.TOperation>(op: Op): zen.TOperationResult<Op>;
  execMany<Op extends zen.TOperation>(ops: Op[]): zen.TOperationResult<Op>[];
  readonly sqlDb: Database;
}

export function DbDatabase(sqlDb: Database): TDbDatabase {
  return {
    exec,
    execMany,
    sqlDb,
  };

  function exec<Op extends zen.TOperation>(op: Op): zen.TOperationResult<Op> {
    if (op.kind === "CreateTable") {
      sqlDb.exec(op.sql);
      return opResult<zen.TCreateTableOperation>(null);
    }
    if (op.kind === "DropTable") {
      sqlDb.exec(op.sql);
      return opResult<zen.TDropTableOperation>(null);
    }
    if (op.kind === "Insert") {
      sqlDb.prepare(op.sql).run(op.params);
      return opResult<zen.TInsertOperation<any>>(op.parse());
    }
    if (op.kind === "InsertMany") {
      sqlDb.prepare(op.sql).run(op.params);
      return opResult<zen.TInsertOperation<any>>(op.parse());
    }
    if (op.kind === "Delete") {
      const stmt = sqlDb.prepare(op.sql);
      const res = op.params ? stmt.run(op.params) : stmt.run();
      return opResult<zen.TDeleteOperation>(op.parse({ deleted: res }));
    }
    if (op.kind === "Update") {
      const stmt = sqlDb.prepare(op.sql);
      const res = op.params ? stmt.run(op.params) : stmt.run();
      return opResult<zen.TUpdateOperation>(op.parse({ updated: res }));
    }
    if (op.kind === "Query") {
      const stmt = sqlDb.prepare(op.sql);
      const res = op.params ? stmt.all(op.params) : stmt.all();
      return opResult<zen.TQueryOperation<any>>(
        op.parse(res as Record<string, any>[]),
      );
    }
    if (op.kind === "ListTables") {
      const res = sqlDb.prepare(op.sql).all();
      return opResult<zen.TListTablesOperation>(
        op.parse(res as Record<string, any>[]),
      );
    }
    if (op.kind === "Pragma") {
      const res = sqlDb.prepare(op.sql).all();
      return opResult<zen.TPragmaOperation<any>>(
        op.parse(res as Record<string, any>[]),
      );
    }
    if (op.kind === "PragmaSet") {
      sqlDb.prepare(op.sql).run();
      return opResult<zen.TPragmaSetOperation>(null);
    }
    return expectNever(op);
  }

  function opResult<Op extends zen.TOperation>(
    res: zen.TOperationResult<Op>,
  ): zen.TOperationResult<zen.TOperation> {
    return res;
  }

  function execMany<Op extends zen.TOperation>(
    ops: Op[],
  ): zen.TOperationResult<Op>[] {
    return ops.map((op) => exec(op));
  }
}

function expectNever(val: never): never {
  throw new Error(`Unexpected value: ${val as any}`);
}