Mock Data Generator — C# source

// mock-data-generator — C# port of the CosmoDev tool.
// The seeded mulberry32 PRNG (bit-identical to src/lib/mockData.ts and the Go
// twin) drives a representative field set; uint wraps exactly like the JS
// `>>> 0` reference, so the same (schema, count, seed) rebuilds the same rows.
using System;
using System.Collections.Generic;

static class MockData
{
    static readonly string[] First =
        { "Ava", "Liam", "Noah", "Emma", "Olivia", "Aiden", "Sophia", "Mason" };
    static readonly string[] Last =
        { "Smith", "Johnson", "Williams", "Brown", "Jones", "Garcia", "Miller", "Davis" };

    // Closure carries the state, mirroring the TS lib's consumption order.
    static Func<double> Mulberry32(uint seed) {
        uint a = seed;
        return () => {
            a += 0x6D2B79F5u;
            uint t = (a ^ (a >> 15)) * (1u | a);   // Math.imul: uint wraps
            t = (t + (t ^ (t >> 7)) * (61u | t)) ^ t;
            return (t ^ (t >> 14)) / 4294967296.0; // >>> 0, scaled to [0,1)
        };
    }

    // Representative fields from the schema dispatch in mockData.ts.
    static object Field(string type, int index, Func<double> rand, int min, int max) {
        switch (type) {
            case "index":
                return index; // no draw
            case "email": {   // two draws, like TS
                string f = First[(int)(rand() * First.Length)].ToLowerInvariant();
                string l = Last[(int)(rand() * Last.Length)].ToLowerInvariant();
                return $"{f}.{l}@example.com";
            }
            case "integer":
                return min + (int)(rand() * (max - min + 1));
            case "boolean":
                return rand() < 0.5;
            default:
                return null; // unknown type -> null
        }
    }

    static void Main() {
        var rand = Mulberry32(1234); // seed
        var schema = new (string name, string type, int min, int max)[] {
            ("id", "index", 0, 0),
            ("email", "email", 0, 0),
            ("age", "integer", 18, 65),
            ("active", "boolean", 0, 0),
        };
        var rows = new List<Dictionary<string, object>>();

        for (int i = 0; i < 3; i++) { // count
            var row = new Dictionary<string, object>();
            foreach (var spec in schema)
                row[spec.name] = Field(spec.type, i, rand, spec.min, spec.max);
            rows.Add(row);
        }
        rows.ForEach(r => Console.WriteLine(
            $"{{ id={r["id"]}, email={r["email"]}, age={r["age"]}, active={r["active"]} }}"));
    }
}