Rules

gistfile1.txt

// Program.cs
// Single-file .NET console demo:
// - Input is an "envelope" containing JSONL lines (transactions from any source)
// - No DTOs: each line is parsed into Dictionary<string, object?>
// - RulesEngine runs rules against the dictionary using safe helper functions (no missing-property crashes)
// - Classification + post-classification field modifications are driven by the rules JSON (Properties.Patches)
//   (set/copy/rename/remove/mul/add/setIfNull)
//
// Setup:
//   dotnet new console -n TxnRulesAgnosticDemo
//   cd TxnRulesAgnosticDemo
//   dotnet add package RulesEngine
//   replace Program.cs with this file
//   dotnet run

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading.Tasks;
using RulesEngine;
using RulesEngine.Models;

public static class Program
{
    public static async Task Main()
    {
        // 1) Hard-coded rules JSON (this is what you'd externalize to a file/db later).
        //    - Expressions call Fns.* for safe access across heterogeneous payloads.
        //    - Each rule has Properties.Category and Properties.Patches for controlled modifications.
        //
        // Notes on expressions:
        // - Use Fns.Has(t,"field") to check existence
        // - Use Fns.GetDecimal/GetString/GetBool to safely read/convert
        // - Use Fns.EqString / Fns.Contains to match strings safely
        //
        // Patches (Properties.Patches) supported ops:
        // - set:       { op:"set", path:"field", value: <any> }
        // - setIfNull: { op:"setIfNull", path:"field", value: <any> }
        // - copy:      { op:"copy", from:"fieldA", path:"fieldB" }
        // - rename:    { op:"rename", from:"old", path:"new" }
        // - remove:    { op:"remove", path:"field" }
        // - mul:       { op:"mul", path:"amount", factor: 0.01 }
        // - add:       { op:"add", path:"amount", value: 5 }
        var workflowsJson = """
        [
          {
            "WorkflowName": "TxnClassify",
            "Rules": [
              {
                "RuleName": "BillingTransaction_ByXmlG",
                "RuleExpressionType": "LambdaExpression",
                "Expression": "Fns.Has(t,\"xml_g\") && Fns.GetDecimal(t,\"xml_g\") > 10 && !Fns.EqString(t,\"kind\",\"RETURN\")",
                "Priority": 10,
                "Properties": {
                  "Category": "BILLING_TRANSACTION",
                  "Patches": [
                    { "op": "set", "path": "classification", "value": "BILLING_TRANSACTION" },
                    { "op": "copy", "from": "xml_g", "path": "amount_raw" },
                    { "op": "set", "path": "currency", "value": "USD" },
                    { "op": "mul", "path": "amount_raw", "factor": 0.01 },
                    { "op": "rename", "from": "day", "path": "service_date" }
                  ]
                }
              },
              {
                "RuleName": "Return_ByKindOrTransId",
                "RuleExpressionType": "LambdaExpression",
                "Expression": "Fns.EqString(t,\"kind\",\"RETURN\") || Fns.Contains(t,\"transid\",\"-R\")",
                "Priority": 20,
                "Properties": {
                  "Category": "RETURN",
                  "Patches": [
                    { "op": "set", "path": "classification", "value": "RETURN" },
                    { "op": "copy", "from": "xml_g", "path": "amount_raw" },
                    { "op": "mul", "path": "amount_raw", "factor": -0.01 }
                  ]
                }
              },
              {
                "RuleName": "Adjustment_ByTypeOrFlags",
                "RuleExpressionType": "LambdaExpression",
                "Expression": "Fns.EqString(t,\"kind\",\"ADJ\") || Fns.EqInt(t,\"type\",2) || Fns.GetBool(t,\"isAdjustment\")==true",
                "Priority": 30,
                "Properties": {
                  "Category": "ADJUSTMENT",
                  "Patches": [
                    { "op": "set", "path": "classification", "value": "ADJUSTMENT" },
                    { "op": "setIfNull", "path": "reason", "value": "Unspecified adjustment" },
                    { "op": "copy", "from": "xml_g", "path": "amount_raw" }
                  ]
                }
              },
              {
                "RuleName": "Fallback_Unclassified",
                "RuleExpressionType": "LambdaExpression",
                "Expression": "true",
                "Priority": 999,
                "Properties": {
                  "Category": "UNCLASSIFIED",
                  "Patches": [
                    { "op": "set", "path": "classification", "value": "UNCLASSIFIED" }
                  ]
                }
              }
            ]
          }
        ]
        """;

        var workflows = JsonSerializer.Deserialize<Workflow[]>(workflowsJson, JsonOptions())
                        ?? throw new InvalidOperationException("Failed to deserialize workflows JSON.");

        // Allow calling helper functions in expressions.
        var settings = new ReSettings
        {
            CustomTypes = new[] { typeof(Fns) }
        };

        var engine = new RulesEngine.RulesEngine(workflows, settings);

        // 2) Simulate an incoming envelope with JSONL lines (source-agnostic).
        // In practice, you'd receive the envelope via HTTP and read lines from the payload.
        var envelopeJson = """
        {
          "source": "EHR_ANY",
          "batchId": "batch-001",
          "payloadJsonl": "{
            \\"transid\\":\\"12345-1-138847\\",\\"invoiceid\\":138847,\\"day\\":\\"2019-01-02\\",\\"xml_g\\":\\"11000\\",\\"kind\\":\\"CHARGE\\"
          }\\n{
            \\"transid\\":\\"12345-2-138847-R\\",\\"invoiceid\\":138847,\\"day\\":\\"2019-01-02\\",\\"xml_g\\":\\"2500\\"
          }\\n{
            \\"transid\\":\\"12345-3-138847\\",\\"invoiceid\\":138847,\\"day\\":\\"2019-01-02\\",\\"xml_g\\":\\"500\\",\\"kind\\":\\"ADJ\\",\\"isAdjustment\\":true
          }"
        }
        """;

        var envelope = JsonDocument.Parse(envelopeJson).RootElement;

        var source = envelope.TryGetProperty("source", out var sEl) ? sEl.GetString() : null;
        var batchId = envelope.TryGetProperty("batchId", out var bEl) ? bEl.GetString() : null;
        var payloadJsonl = envelope.GetProperty("payloadJsonl").GetString() ?? "";

        // 3) Parse JSONL lines -> dictionaries.
        var lines = payloadJsonl
            .Split('\n', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);

        var outputRecords = new List<Dictionary<string, object?>>();

        foreach (var line in lines)
        {
            var txn = JsonToDictionary(line);

            // Add envelope metadata (optional but common).
            txn["source"] = source;
            txn["batchId"] = batchId;

            // Run rules for this transaction.
            var results = await engine.ExecuteAllRulesAsync(
                "TxnClassify",
                new RuleParameter("t", txn)
            );

            // Choose the "best" rule: lowest Priority number among successes (i.e., highest precedence).
            var matched = results
                .Where(r => r.IsSuccess)
                .OrderBy(r => r.Rule?.Priority ?? int.MaxValue)
                .FirstOrDefault();

            if (matched is null || matched.Rule is null)
            {
                // Should not happen because fallback rule returns true, but keep defensive.
                txn["classification"] = "UNCLASSIFIED";
                txn["_matchedRule"] = null;
                outputRecords.Add(txn);
                continue;
            }

            // Create a new record for downstream storage (clone + modifications).
            var newRecord = new Dictionary<string, object?>(txn, StringComparer.OrdinalIgnoreCase)
            {
                ["_matchedRule"] = matched.Rule.RuleName
            };

            // Apply patch-driven modifications from rule JSON.
            ApplyPatchesFromRuleProperties(matched.Rule.Properties, newRecord);

            outputRecords.Add(newRecord);
        }

        // 4) Print results (what you'd post to your API / write to transfer tables).
        Console.WriteLine("=== Output Records ===");
        foreach (var rec in outputRecords)
        {
            Console.WriteLine(JsonSerializer.Serialize(rec, JsonOptions()));
            Console.WriteLine("----");
        }
    }

    private static JsonSerializerOptions JsonOptions()
        => new()
        {
            WriteIndented = true,
            PropertyNameCaseInsensitive = true
        };

    // Parse a JSON object string into a Dictionary<string, object?> (recursive).
    private static Dictionary<string, object?> JsonToDictionary(string json)
    {
        using var doc = JsonDocument.Parse(json);
        if (doc.RootElement.ValueKind != JsonValueKind.Object)
            throw new InvalidOperationException("Each JSONL line must be a JSON object.");

        return (Dictionary<string, object?>)FromJsonElement(doc.RootElement)!;
    }

    private static object? FromJsonElement(JsonElement el)
    {
        switch (el.ValueKind)
        {
            case JsonValueKind.Object:
            {
                var dict = new Dictionary<string, object?>(StringComparer.OrdinalIgnoreCase);
                foreach (var p in el.EnumerateObject())
                    dict[p.Name] = FromJsonElement(p.Value);
                return dict;
            }
            case JsonValueKind.Array:
            {
                var list = new List<object?>();
                foreach (var i in el.EnumerateArray())
                    list.Add(FromJsonElement(i));
                return list;
            }
            case JsonValueKind.String:
                return el.GetString();
            case JsonValueKind.Number:
                if (el.TryGetInt64(out var l)) return l;
                if (el.TryGetDecimal(out var d)) return d;
                return el.ToString();
            case JsonValueKind.True:
                return true;
            case JsonValueKind.False:
                return false;
            case JsonValueKind.Null:
            case JsonValueKind.Undefined:
                return null;
            default:
                return el.ToString();
        }
    }

    // Applies patches stored under rule.Properties["Patches"].
    // Because RulesEngine deserialization often yields JsonElement for nested objects, we handle JsonElement and CLR types.
    private static void ApplyPatchesFromRuleProperties(IDictionary<string, object>? properties, Dictionary<string, object?> record)
    {
        if (properties is null) return;

        // Also apply a simple "Category" property as a standard field if present.
        if (properties.TryGetValue("Category", out var categoryObj))
        {
            var category = UnwrapToString(categoryObj);
            if (!string.IsNullOrWhiteSpace(category))
                record["category"] = category;
        }

        if (!properties.TryGetValue("Patches", out var patchesObj) || patchesObj is null)
            return;

        // Patches can come through as JsonElement or as List<object>.
        if (patchesObj is JsonElement je && je.ValueKind == JsonValueKind.Array)
        {
            foreach (var patchEl in je.EnumerateArray())
                ApplySinglePatch(patchEl, record);
            return;
        }

        if (patchesObj is IEnumerable<object> list)
        {
            foreach (var item in list)
            {
                if (item is JsonElement jel)
                    ApplySinglePatch(jel, record);
                else if (item is IDictionary<string, object?> patchDict)
                    ApplySinglePatch(patchDict, record);
            }
        }
    }

    private static void ApplySinglePatch(JsonElement patchEl, Dictionary<string, object?> record)
    {
        if (patchEl.ValueKind != JsonValueKind.Object) return;

        string op = patchEl.TryGetProperty("op", out var opEl) ? (opEl.GetString() ?? "") : "";
        string path = patchEl.TryGetProperty("path", out var pathEl) ? (pathEl.GetString() ?? "") : "";
        string from = patchEl.TryGetProperty("from", out var fromEl) ? (fromEl.GetString() ?? "") : "";

        op = op.Trim();
        path = path.Trim();
        from = from.Trim();

        switch (op)
        {
            case "set":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                var value = patchEl.TryGetProperty("value", out var vEl) ? FromJsonElement(vEl) : null;
                record[path] = value;
                break;
            }
            case "setIfNull":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                if (!record.TryGetValue(path, out var existing) || existing is null || (existing is string s && string.IsNullOrWhiteSpace(s)))
                {
                    var value = patchEl.TryGetProperty("value", out var vEl) ? FromJsonElement(vEl) : null;
                    record[path] = value;
                }
                break;
            }
            case "copy":
            {
                if (string.IsNullOrWhiteSpace(from) || string.IsNullOrWhiteSpace(path)) return;
                record.TryGetValue(from, out var val);
                record[path] = val;
                break;
            }
            case "rename":
            {
                if (string.IsNullOrWhiteSpace(from) || string.IsNullOrWhiteSpace(path)) return;
                if (record.TryGetValue(from, out var val))
                {
                    record.Remove(from);
                    record[path] = val;
                }
                break;
            }
            case "remove":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                record.Remove(path);
                break;
            }
            case "mul":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                if (!record.TryGetValue(path, out var val) || val is null) return;

                var factor = patchEl.TryGetProperty("factor", out var fEl) ? ToDecimal(FromJsonElement(fEl)) : null;
                var number = ToDecimal(val);
                if (factor is null || number is null) return;

                record[path] = number.Value * factor.Value;
                break;
            }
            case "add":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                if (!record.TryGetValue(path, out var val) || val is null) return;

                var addend = patchEl.TryGetProperty("value", out var aEl) ? ToDecimal(FromJsonElement(aEl)) : null;
                var number = ToDecimal(val);
                if (addend is null || number is null) return;

                record[path] = number.Value + addend.Value;
                break;
            }
        }
    }

    private static void ApplySinglePatch(IDictionary<string, object?> patch, Dictionary<string, object?> record)
    {
        patch.TryGetValue("op", out var opObj);
        patch.TryGetValue("path", out var pathObj);
        patch.TryGetValue("from", out var fromObj);

        var op = (opObj?.ToString() ?? "").Trim();
        var path = (pathObj?.ToString() ?? "").Trim();
        var from = (fromObj?.ToString() ?? "").Trim();

        switch (op)
        {
            case "set":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                patch.TryGetValue("value", out var value);
                record[path] = value;
                break;
            }
            case "setIfNull":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                if (!record.TryGetValue(path, out var existing) || existing is null || (existing is string s && string.IsNullOrWhiteSpace(s)))
                {
                    patch.TryGetValue("value", out var value);
                    record[path] = value;
                }
                break;
            }
            case "copy":
            {
                if (string.IsNullOrWhiteSpace(from) || string.IsNullOrWhiteSpace(path)) return;
                record.TryGetValue(from, out var val);
                record[path] = val;
                break;
            }
            case "rename":
            {
                if (string.IsNullOrWhiteSpace(from) || string.IsNullOrWhiteSpace(path)) return;
                if (record.TryGetValue(from, out var val))
                {
                    record.Remove(from);
                    record[path] = val;
                }
                break;
            }
            case "remove":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                record.Remove(path);
                break;
            }
            case "mul":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                if (!record.TryGetValue(path, out var val) || val is null) return;

                patch.TryGetValue("factor", out var factorObj);
                var factor = ToDecimal(factorObj);
                var number = ToDecimal(val);
                if (factor is null || number is null) return;

                record[path] = number.Value * factor.Value;
                break;
            }
            case "add":
            {
                if (string.IsNullOrWhiteSpace(path)) return;
                if (!record.TryGetValue(path, out var val) || val is null) return;

                patch.TryGetValue("value", out var addObj);
                var addend = ToDecimal(addObj);
                var number = ToDecimal(val);
                if (addend is null || number is null) return;

                record[path] = number.Value + addend.Value;
                break;
            }
        }
    }

    private static string? UnwrapToString(object obj)
    {
        if (obj is null) return null;
        if (obj is JsonElement je)
        {
            return je.ValueKind switch
            {
                JsonValueKind.String => je.GetString(),
                JsonValueKind.Number => je.ToString(),
                JsonValueKind.True => "true",
                JsonValueKind.False => "false",
                _ => je.ToString()
            };
        }
        return obj.ToString();
    }

    private static decimal? ToDecimal(object? obj)
    {
        if (obj is null) return null;

        if (obj is decimal d) return d;
        if (obj is long l) return l;
        if (obj is int i) return i;
        if (obj is double db) return (decimal)db;
        if (obj is float f) return (decimal)f;

        if (obj is JsonElement je)
        {
            if (je.ValueKind == JsonValueKind.Number && je.TryGetDecimal(out var jd)) return jd;
            if (je.ValueKind == JsonValueKind.String)
            {
                var s = je.GetString();
                if (decimal.TryParse(s, NumberStyles.Any, CultureInfo.InvariantCulture, out var parsed)) return parsed;
            }
            return null;
        }

        if (obj is string s2)
        {
            if (decimal.TryParse(s2, NumberStyles.Any, CultureInfo.InvariantCulture, out var parsed)) return parsed;
            return null;
        }

        return null;
    }
}

// Helper functions intended for rule expressions.
// IMPORTANT: Expressions run against IDictionary<string, object?> (source-agnostic) and must be safe on missing fields.
public static class Fns
{
    public static bool Has(IDictionary<string, object?> t, string key)
        => t is not null && t.ContainsKey(key);

    public static string? GetString(IDictionary<string, object?> t, string key)
    {
        if (t is null || !t.TryGetValue(key, out var v) || v is null) return null;
        if (v is JsonElement je)
        {
            if (je.ValueKind == JsonValueKind.String) return je.GetString();
            return je.ToString();
        }
        return v.ToString();
    }

    public static bool? GetBool(IDictionary<string, object?> t, string key)
    {
        if (t is null || !t.TryGetValue(key, out var v) || v is null) return null;
        if (v is bool b) return b;
        if (v is JsonElement je)
        {
            if (je.ValueKind == JsonValueKind.True) return true;
            if (je.ValueKind == JsonValueKind.False) return false;
            if (je.ValueKind == JsonValueKind.String && bool.TryParse(je.GetString(), out var pb)) return pb;
        }
        if (v is string s && bool.TryParse(s, out var b2)) return b2;
        return null;
    }

    public static decimal GetDecimal(IDictionary<string, object?> t, string key)
    {
        // Returns 0 if missing/unparseable; use Has(...) to guard when needed.
        if (t is null || !t.TryGetValue(key, out var v) || v is null) return 0m;

        if (v is decimal d) return d;
        if (v is long l) return l;
        if (v is int i) return i;
        if (v is double db) return (decimal)db;
        if (v is float f) return (decimal)f;

        if (v is JsonElement je)
        {
            if (je.ValueKind == JsonValueKind.Number && je.TryGetDecimal(out var jd)) return jd;
            if (je.ValueKind == JsonValueKind.String)
            {
                var s = je.GetString();
                if (decimal.TryParse(s, NumberStyles.Any, CultureInfo.InvariantCulture, out var parsed)) return parsed;
                return 0m;
            }
            return 0m;
        }

        if (v is string s2)
        {
            if (decimal.TryParse(s2, NumberStyles.Any, CultureInfo.InvariantCulture, out var parsed)) return parsed;
            return 0m;
        }

        return 0m;
    }

    public static int GetInt(IDictionary<string, object?> t, string key)
    {
        if (t is null || !t.TryGetValue(key, out var v) || v is null) return 0;
        if (v is int i) return i;
        if (v is long l) return (int)l;
        if (v is JsonElement je)
        {
            if (je.ValueKind == JsonValueKind.Number && je.TryGetInt32(out var ji)) return ji;
            if (je.ValueKind == JsonValueKind.String && int.TryParse(je.GetString(), out var pi)) return pi;
        }
        if (v is string s && int.TryParse(s, out var pi2)) return pi2;
        return 0;
    }

    public static bool EqString(IDictionary<string, object?> t, string key, string expected)
    {
        var s = GetString(t, key);
        if (s is null) return false;
        return string.Equals(s, expected, StringComparison.OrdinalIgnoreCase);
    }

    public static bool Contains(IDictionary<string, object?> t, string key, string fragment)
    {
        var s = GetString(t, key);
        if (s is null) return false;
        return s.IndexOf(fragment, StringComparison.OrdinalIgnoreCase) >= 0;
    }

    public static bool EqInt(IDictionary<string, object?> t, string key, int expected)
        => GetInt(t, key) == expected;
}